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Sample records for anterior transpedicular screw

  1. Morphological character of cervical spine for anterior transpedicular screw fixation

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    Rong-Ping Zhou

    2013-01-01

    Full Text Available Background: Anterior cervical interbody grafts/cages combined with a plate were frequently used in multilevel discectomies/corpectomies. In order to avoid additional posterior stabilization in patients who undergo anterior reconstructive surgery, an anterior cervical transpedicular screw fixation, which offers higher stability is desirable. We investigated in this study the anatomical (morphologic characters for cervical anterior transpedicular screw fixation. Materials and Methods: Left pedicle parameters were measured on computed tomography (CT images based on 36 cervical spine CT scans from healthy subjects. The parameters included outer pedicle width (Distance from lateral to medial pedicle surface in the coronal plane, outer pedicle height (OPH (Distance from upper to lower pedicle surface in the sagittal plane, maximal pedicle axis length (MPAL, distance transverse insertion point (DIP, distance of the insertion point to the upper end plate (DIUP, pedicle sagittal transverse angle (PSTA and pedicle transverse angle (PTA at C3 to C7. Results: The values of outer pedicle width and MPAL in males were larger than in females from C3 to C7. The OPH in males was larger than in females at C3 to C6, but there was no difference at C7. The DIP and PTA were significantly greater in males than in females at C3, but there was no difference in the angle at C4-7. The PSTA was not statistically different between genders at C3, 4, 7, but this value in males was larger than females at C5, 6. The DIUP was significantly greater in males at C3, 4, 6, 7 but was non significant at C5. Conclusions: The placement of cervical anterior transpedicular screws should be individualized for each patient and based on a detailed preoperative planning.

  2. Advances in cervical anterior transpedicular screw fixation technique%颈椎前路椎弓根螺钉内固定技术的研究进展

    Institute of Scientific and Technical Information of China (English)

    欧阳钧; 吴卫东

    2013-01-01

    Cervical posterior transpedicular screw technique was first introduced to clinic in 1994. Due to its good biomechanical stability and satisfactory fusion effect,it has become a major solution to some cervical spine diseases.However,most of the diseases involved in vertebral body and posterior transpedicular screw technique is complex and difficult,these factors prevent the technique be widely used in cervical spine surgery.In 2008,a new concept of cervical anterior transpedicular screw fixation technique was first proposed.This new technique inherited advantages of posterior transpedicular screw fixation,and of course,it also overcomes drawbacks of conventional anterior vertebral body screw fixa-tion.This review presents an overview of anterior transpedicular screw fixation technique on anatomical and biomechanical field.%颈椎后路椎弓根螺钉固定技术于1994年首次应用于临床,鉴于其稳定的固定融合效果,已成为多种颈椎疾病的主要治疗手段。然而,由于颈椎病灶的好发部位多位于前部,且颈椎后路椎弓根螺钉操作难度较大,在一定程度上限制了该技术的发展。2008年颈椎前路椎弓根螺钉固定技术的概念被首次提出,此技术继承了后路椎弓根螺钉生物力学性能卓越的优点,且克服传统颈椎前路椎体螺钉稳定性较差的缺点。本文主要就颈椎前路椎弓根螺钉固定技术的解剖学及生物力学研究进展进行综述。

  3. CT morphometric analysis to determine the anatomical basis for the use of transpedicular screws during reconstruction and fixations of anterior cervical vertebrae.

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    Chun Chen

    Full Text Available BACKGROUND: Accurate placement of pedicle screw during Anterior Transpedicular Screw fixation (ATPS in cervical spine depends on accurate anatomical knowledge of the vertebrae. However, little is known of the morphometric characteristics of cervical vertebrae in Chinese population. METHODS: Three-dimensional reconstructions of CT images were performed for 80 cases. The anatomic data and screw fixation parameters for ATPS fixation were measured using the Mimics software. FINDINGS: The overall mean OPW, OPH and PAL ranged from 5.81 to 7.49 mm, 7.77 to 8.69 mm, and 33.40 to 31.13 mm separately, and SPA was 93.54 to 109.36 degrees from C3 to C6, 104.99 degrees at C7, whereas, 49.00 to 32.26 degrees from C4 to C7, 46.79 degrees at C3 (TPA. Dl/rSIP had an increasing trend away from upper endplate with mean value from 1.87 to 5.83 mm. Dl/rTIP was located at the lateral portion of the anterior cortex of vertebrae for C3 to C5 and ipsilateral for C6 to C7 with mean value from -2.70 to -3.00 mm, and 0.17 to 3.18 mm. The entrance points for pedicular screw insertion for C3 to C5 and C6 to C7 were recommended -2∼-3 mm and 0-4 mm from the median sagittal plane, respectively, 1-4 mm and 5-6 mm from the upper endplate, with TPA being 46.79-49.00 degrees and 40.89-32.26 degrees, respectively, and SPA being 93.54-106.69 degrees and 109.36-104.99 degrees, respectively. The pedicle screw insertion diameter was recommended 3.5 mm (C3 and C4, 4.0 mm (C5 to C7, and the pedicle axial length was 21-24 mm for C3 to C7 for both genders. However, the ATPS insertion in C3 should be individualized given its relatively small anatomical dimensions. CONCLUSIONS: The data provided a morphometric basis for the ATPS fixation technique in lower cervical fixation. It will help in preoperative planning and execution of this surgery.

  4. Construction and accuracy assessment of patient-specific biocompatible drill template for cervical anterior transpedicular screw (ATPS insertion: an in vitro study.

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    Maoqing Fu

    Full Text Available BACKGROUND: With the properties of three-column fixation and anterior-approach-only procedure, anterior transpedicular screw (ATPS is ideal for severe multilevel traumatic cervical instabilities. However, the accurate insertion of ATPS remains challenging. Here we constructed a patient-specific biocompatible drill template and evaluated its accuracy in assisting ATPS insertion. METHODS: After ethical approval, 24 formalin-preserved cervical vertebrae (C2-C7 were CT scanned. 3D reconstruction models of cervical vertebra were obtained with 2-mm-diameter virtual pin tracts at the central pedicles. The 3D models were used for rapid prototyping (RP printing. A 2-mm-diameter Kirschner wire was then inserted into the pin tract of the RP model before polymethylmethacrylate was used to construct the patient-specific biocompatible drill template. After removal of the anterior soft tissue, a 2-mm-diameter Kirschner wire was inserted into the cervical pedicle with the assistance of drill template. Cadaveric cervical spines with pin tracts were subsequently scanned using the same CT scanner. A 3D reconstruction was performed of the scanned spines to get 3D models of the vertebrae containing the actual pin tracts. The deviations were calculated between 3D models with virtual and actual pin tracts at the middle point of the cervical pedicle. 3D models of 3.5 mm-diameter screws were used in simulated insertion to grade the screw positions. FINDINGS: The patient-specific biocompatible drill template was constructed to assist ATPS insertion successfully. There were no significant differences between medial/lateral deviations (P = 0.797 or between superior/inferior deviations (P = 0.741. The absolute deviation values were 0.82±0.75 mm and 1.10±0.96 mm in axial and sagittal planes, respectively. In the simulated insertion, the screws in non-critical position were 44/48 (91.7%. CONCLUSIONS: The patient-specific drill template is biocompatible, easy

  5. SURVEY SUBAXIAL CERVICAL VERTEBRAE FOR TRANSPEDICULAR SCREW FIXATION

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    Objective In this study, the pedicles of subaxial vertebrae from C3 to C7 were measured to provide some morphometric data for cervical transpedicular screw fixation. Methods 20 dried bone cervical spinal columns (C3-C7), pedicle dimensions (pedicle height, width, length), and transverse and sagittal angles of the pedicles were performed with vernier in linear and angular measurements. Results The obtained data revealed that the mean values were approximately ranging from 6.7 to 7.2 mm for pedicle height, 4.4 to 4.9 mm for pedicle width, 22.2 to 27.7 mm for pedicle axis length, 42.3° to 51.5° for transverse angle, and 5.2° to 14.1° for sagittal angle. Conclusion Linear measurements of pedicle dimensions and also axial angles from horizontal and vertical planes may provide some anatomic limitations for subaxial cervical transpedicular screw fixation, and also contribute to the safety of the surgical procedure.

  6. Transpedicular screw fixation in the thoracic and lumbar spine with a novel cannulated polyaxial screw system

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    Lutz Weise

    2008-10-01

    Full Text Available Lutz Weise, Olaf Suess, Thomas Picht, Theodoros KombosNeurochirurgische Klinik, Charité – Universitätsmedizin Berlin, Berlin, GermanyObjective: Transpedicular screws are commonly and successfully used for posterior fixation in spinal instability, but their insertion remains challenging. Even using navigation techniques, there is a misplacement rate of up to 11%. The aim of this study was to assess the accuracy of a novel pedicle screw system.Methods: Thoracic and lumbar fusions were performed on 67 consecutive patients for tumor, trauma, degenerative disease or infection. A total of 326 pedicular screws were placed using a novel wire-guided, cannulated, polyaxial screw system (XIA Precision®, Stryker. The accuracy of placement was assessed post operatively by CT scan, and the patients were followed-up clinically for a mean of 16 months.Results: The total medio-caudal pedicle wall perforation rate was 9.2% (30/326. In 19 of these 30 cases a cortical breakthrough of less than 2 mm occurred. The misplacement rate (defined as a perforation of 2 mm or more was 3.37% (11/326. Three of these 11 screws needed surgical revision due to neurological symptoms or CSF leakage. There have been no screw breakages or dislocations over the follow up-period.Conclusion: We conclude that the use of this cannulated screw system for the placement of pedicle screws in the thoracic and lumbar spine is accurate and safe. The advantages of this technique include easy handling without a time-consuming set up. Considering the incidence of long-term screw breakage, further investigation with a longer follow-up period is necessary.Keywords: spinal instrumentation, pedicle screws, misplacement, pedicle wall perforation

  7. Accuracy and complications of transpedicular C2 screw placement without the use of spinal navigation.

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    Mueller, Christian-Andreas; Roesseler, Lukas; Podlogar, Martin; Kovacs, Attlila; Kristof, Rudolf Andreas

    2010-05-01

    The objective of the study was to describe the technique, accuracy of placement and complications of transpedicular C2 screw fixation without spinal navigation. Patients treated by C2 pedicle screw fixations were identified from the surgical log book of the department. Clinical data were extracted retrospectively from the patients' charts. Pedicle screw placement accuracy was assessed on postoperative CT scans according to Gertzbein and Robbins (GRGr). A total of 27 patients were included in the study. The mean age of the patients was 56 +/- 22.0 years; 51.9% of them were female. As much as 17 patients suffered from trauma, 5 of degenerative disease, 3 of inflammations and 2 of metastatic disease. A total of 47 C2 transpedicular screw fixations were performed. The canulated screws were inserted under visual control following the preparation of the superior surface of the isthmus and of the medial surface of the pedicles of the C2. Intraoperative fluoroscopy was additionally used. The postoperative CT findings showed in 55.3% GRGr 1, in 27.7% GRGr 2, in 10.6% GRGr 3, and in 6.3% GRGr 4 pedicle screw insertion accuracy. Screw insertions GRGr 5 were not observed. Screw malpositioning (i.e., GRGr 3 and 4) was significantly associated with thin (C2 fractures. In the three patients with screw insertions GRGr 4, postoperative angiographies were performed to exclude vertebral artery affections. In one of these three cases, the screw caused a clinically asymptomatic vertebral artery compression. Hardware failures did not occur. In one patient, postoperative pneumonia resulted in the death of the patient. Careful patient selection and surgical technique is necessary to avoid vertebral artery injury in C2 pedicle screw fixation without spinal navigation. A slight opening of the vertebral artery canal (Gertzbein and Robbins grade C2 pedicle screw insertions.

  8. Posterior interbody fusion using a diagonal cage with unilateral transpedicular screw fixation for lumbar stenosis.

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    Zhao, Jian; Zhang, Feng; Chen, Xiaoqing; Yao, Yu

    2011-03-01

    Few reports have described the combined use of unilateral pedicle screw fixation and interbody fusion for lumbar stenosis. We retrospectively reviewed 79 patients with lumbar stenosis. The rationale and effectiveness of unilateral pedicle screw fixation were studied from biomechanical and clinical perspectives, aiming to reduce stiffness of the implant. All patients were operated with posterior interbody fusion using a diagonal cage in combination with unilateral transpedicular screw fixation and had reached the 3-year follow-up interval after operation. The mean operating time was 115 minutes (range=95-150 min) and the mean estimated blood loss was 150 mL (range=100-200 mL). The mean duration of hospital stay was 10 days (range=7-15 days). Clinical outcomes were assessed prior to surgery and reassessed at intervals using Denis' pain and work scales. Fusion status was determined from X-rays and CT scans. At the final follow-up, the clinical results were satisfactory and patients showed significantly improved scores (pdiagonal cage with unilateral transpedicular fixation is an effective treatment for decompressive surgery for lumbar stenosis.

  9. Posterior lumbar interbody fusion using one diagonal fusion cage with transpedicular screw/rod fixation.

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    Zhao, Jie; Hou, Tiesheng; Wang, Xinwei; Ma, Shengzhong

    2003-04-01

    Posterior lumbar interbody fusion (PLIF) using threaded cages has gained wide popularity for lumbosacral spinal disease. Our biomechanical tests showed that PLIF using a single diagonal cage with unilateral facetectomy does add a little to spinal stability and provides equal or even higher postoperative stability than PLIF using two posterior cages with bilateral facetectomy. Studies also demonstrated that cages placed using a posterior approach did not cause the same increase in spinal stiffness seen with pedicle screw instrumentation, and we concluded that cages should not be used posteriorly without other forms of fixation. On the other hand, placement of two cages using a posterior approach does have the disadvantage of risk to the bilateral nerve roots. We therefore performed a prospective study to determine whether PLIF can be accomplished by utilizing a single diagonal fusion cage with the application of supplemental transpedicular screw/rod instrumentation. Twenty-seven patients underwent a PLIF using one single fusion cage (BAK, Sulzer Spine-Tech, Minneapolis, MN, USA) inserted posterolaterally and oriented anteromedially on the symptomatic side with unilateral facetectomy and at the same level supplemental fixation with a transpedicular screw/rod system. The internal fixation systems included 12 SOCON spinal systems (Aesculap AG, Germany) and 15 TSRH spinal systems (Medtronic Sofamor Danek, USA). The inclusion criteria were grade 1 to 2 lumbar isthmic spondylolisthesis, lumbar degenerative spondylolisthesis, and recurrent lumbar disc herniations with instability. Patients had at least 1 year of low back pain and/or unilateral sciatica and a severely restricted functional ability in individuals aged 28-55 years. Patients with more than grade 2 spondylolisthesis or adjacent-level degeneration were excluded from the study. Patients were clinically assessed prior to surgery by an independent assessor; they were then reassessed at 1, 3, 6, 12, 18, and 24

  10. Comparison of the safety of three methods of lumbar transpedicular screw fixation

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Objective: To choose a proper method of lumbar transpedicular screw fixation at different lumbar levels among the three methods ( Roy-Camille's method, Magerl's method and Du's method) in the Chinese population.Methods: Three-dimensional ( 3-D ) images were reconstructed with image data of 42 adult lumbar segments that were scanned by Electron Beam CT. The three methods of lumbar pedicle screw fixation were simulated on the 3-D reconstructed images and the parameters of implanting pedicle screws were measured.Results: There was statistically significant difference at the distance from the entrance point to the pedicle axis between the three methods (P < 0. 001). The distances measured by Du's method were shortest from L1 to L4,and the distances measured by Magerl's method were shortest at L5 (P < 0.05). There was no significant difference from L1 to L2 (P > 0.05) but significant difference from L3 to L5 at inserting safe ranges of TSA (transverse section angle) was found between the three methods (P <0.05). From L3 to L4, the inserting safe ranges of TSA measured by Du's and Magerl's methods were significantly larger than that measured by Roy-Camille's method (P <0.05), but there was no significant difference between them (P > 0.05). At L5, the inserting safe ranges of TSA measured by Magerl's method were largest among the three methods (P < 0.05).Conclusions: Among the three methods, Du's method is the best choice from L1 to LA because its distance from the entrance point to the pedicle axis is shortest and the safe range of TSA is largest; Magerl's method can be used from L3 to L5 and is the best choice at L5; Roy-Camille's method is applicable at L1 and L2.

  11. Treatment of acute thoracolumbar burst fractures with kyphoplasty and short pedicle screw fixation: Transpedicular intracorporeal grafting with calcium phosphate: A prospective study

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    Korovessis Panagiotis

    2007-01-01

    Full Text Available Background: In the surgical treatment of thoracolumbar fractures, the major problem after posterior correction and transpedicular instrumentation is failure to support the anterior spinal column, leading to loss of correction and instrumentation failure with associated complaints. We conducted this prospective study to evaluate the outcome of the treatment of acute thoracolumbar burst fractures by transpedicular balloon kyphoplasty, grafting with calcium phosphate cement and short pedicle screw fixation plus fusion. Materials and Methods : Twenty-three consecutive patients of thoracolumbar (T 9 to L 4 burst fracture with or without neurologic deficit with an average age of 43 years, were included in this prospective study. Twenty-one from the 23 patients had single burst fracture while the remaining two patients had a burst fracture and additionally an adjacent A1-type fracture. On admission six (26% out of 23 patients had neurological deficit (five incomplete, one complete. Bilateral transpedicular balloon kyphoplasty with liquid calcium phosphate to reduce segmental kyphosis and restore vertebral body height and short (three vertebrae pedicle screw instrumentation with posterolateral fusion was performed. Gardner kyphosis angle, anterior and posterior vertebral body height ratio and spinal canal encroachment were calculated pre- to postoperatively. Results : All 23 patients were operated within two days after admission and were followed for at least 12 months after index surgery. Operating time and blood loss averaged 45 min and 60 cc respectively. The five patients with incomplete neurological lesions improved by at least one ASIA grade, while no neurological deterioration was observed in any case. The VAS and SF-36 (Role physical and Bodily pain domains were significantly improved postoperatively. Overall sagittal alignment was improved from an average preoperative 16° to one degree kyphosis at final follow-up observation. The anterior

  12. Surgical correction of spinal deformity with the use of transpedicular screw spinal systems in children with idiopathic thoracic scoliosis

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    Нурбек Надирович Надиров

    2016-06-01

    Full Text Available Aim.To compare the results of surgical correction of spinal deformity in children with idiopathic thoracic scoliosis with the use of transpedicular screw spinal systems with different pedicle screw placement.Material and methods.Thirty-one patients (14–17 years with spinal curvature with a Cobb angle from 40° to 79° were operated on. Surgical correction of the deformity was performed using two methods, depending on the possible placement of a pedicle screw. The first group included 16 patients for whom the transpedicular support elements were placed on both sides, throughout the completely deformed spine. The second group included 15 patients for whom the pedicle screws were not placed for two or more vertebrae on the concave side of the curve, at the top of the main curve.Results.The mean percent correction of the spinal deformity for the first and second groups was 92.5% and 82.6%, respectively. The mean percentage of derotation of the apical vertebra for the first and second groups was 73.9% and 23%, respectively.Conclusion.The use of data based on the anatomical and anthropometric features of the vertebral body with scoliosis facilitates selection of the best option for correction of thoracic curve in children with idiopathic scoliosis using pedicle multi-support metal construction. The use of the spinal pedicle system for correction of spinal deformity in children with idiopathic scoliosis enabled a uniform load distribution along the support elements of the metal construction and maintained the correction in the late postoperative follow-up period.

  13. Computed tomography-based morphometric analysis of cervical pedicles in Indian population: A pilot study to assess feasibility of transpedicular screw fixation

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    A R Patwardhan

    2012-01-01

    Full Text Available Background: Cervical transpedicular screw fixation is safe and is probably going to be the gold standard for cervical spine fixation. However, cervical transpedicular screw use in the Asian population can be limited as the transverse diameter in this group of patients may not be adequate to accommodate the 3.5-mm pedicular screw thus injuring the vital structures located in the close proximity of the pedicles. Thus lateral mass fixation remains the mainstay of treatment. The present study evaluated the transverse cervical pedicle diameter of C2-C7 vertebrae in a pilot study in 27 Indian subjects using computed tomography (CT imaging and evaluated the feasibility of transpedicular screw fixation in them. Aims: To evaluate the feasibility of transpedicular screw fixation in the Indian population. Settings and Design: The cervical pedicle diameter size differs between the Asian and non-Asian population. The authors studied the transverse pedicle diameter of the C2-C7 of the cervical spine in the Indian population using CT measurements. This cross-sectional study was carried out at a tertiary care centre for a period of four months from October 2010 to December 2010. Material and Methods: Measurements of cervical pedicles in the subjects were performed on the CT workstation from the CT images taken at 2.5-mm interval. The transverse pedicle diameter was defined as the outermost diameter of the pedicle, taken perpendicular to the axis of the pedicle at the narrowest point and measured in millimeters±0.1 mm. Statistical Analysis: Descriptive statistics was used to represent percentage of transverse diameter of cervical pedicles less than 5 mm in male and female subjects at C2-C7 levels. Since there is no previous study done in India, we initiated the study with sample size of 27 as a pilot study. The statistical analysis was performed using SPSS software. Results: The mean transverse diameters of the cervical pedicles of C2, C3, C4, C5, C6 and C7 in

  14. LEVEL OF EVIDENCE IN THE PLACEMENT OF TRANSPEDICULAR SCREWS IN SUBAXIAL CERVICAL SPINE

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    Cristóbal Herrera Palacios

    Full Text Available ABSTRACT The high-energy trauma mainly involves vertebral lesions and 6% occur in the cervical region. This poses a challenge to spine surgeons in surgical decision-making, both in terms of approach as the instrumentation. International recommendations establish that the procedures performed are reproducible, safe, and effective. The techniques for placement of pedicle screws are complicated and have been based on intraoperative navigation (limited by cost and fluoroscopy (greater exposure of health care professionals and patients to radiation. Therefore, the freehand technique is an option. The goal was to identify the level of evidence and grade of recommendation in the medical literature regarding the safety and efficacy of pedicle screw instrumentation with freehand technique in subaxial cervical spine. To this end, we carried out a systematic review with the following MeSH terms: safety, efficacy, vertebral artery. Articles were evaluated twice in a standardized and blind way by two observers skilled in systematic analysis, after CLEIS 3401 authorization in November 2014. Due to the nature of the study and the variables, articles with a high level of evidence and grade of recommendation were not found. Level of Evidence obtained on safety and efficacy in the placement of pedicle screws in subaxial column with freehand technique: 2b. Degree of Recommendation obtained on safety and efficacy in the placement of pedicle screws in subaxial column with freehand technique: B, favorable recommendation.

  15. 下颈椎前路椎弓根螺钉固定系统的有限元法生物力学研究%Three-dimensional finite-element study on anterior transpedicular screw fixation system of the subaxial cervical spine

    Institute of Scientific and Technical Information of China (English)

    李杰; 赵刘军; 祁峰; 马维虎; 徐荣明; 蒋伟宇; 刘王宓; 张明; 洪锦炯

    2015-01-01

    目的 比较下颈椎前路椎弓根螺钉内固定系统(ACTPS)和颈椎前路椎体螺钉钛板系统(ACLP)重建两节椎体次全切后的生物力学特性.方法 选择一名28岁成年健康男性志愿者,采集颈椎(C1 ~T1)的CT数据,应用Mimics 10.0、Rapidform XOR3、Hypermesh10.0、CATIA5 V19、ANSYS14.0软件建立下颈椎三维非线性的(C3~C7)完整模型.在C3上分别施加75 N的轴向压力和1N·m的纯力偶矩,使模型在屈伸、侧弯、旋转方向上运动.将模型的椎间活动度与文献报道的体外生物力学实验数据相比进行验证.建立ACTPS模型和ACLP模型,利用ANSYS计算两种模型在前屈、后伸、侧弯、旋转等工况下的椎间活动度.记录下ACTPS模型组和ACLP模型组的Von Mises应力云图及最大应力值,将ACTPS固定模型、ACLP固定模型的椎间活动度与完整模型进行比较.结果 本次实验建立了健康人的下颈椎(C3~C7)三维非线性有限元模型,模型包括85 832个单元,23 612个节点,其外形逼真,椎间活动度与文献报道的体外生物力学实验结果吻合.ACTPS模型组应力分布的相对比较均匀,ACLP模型组在螺钉与钛板接触部位出现应力集中.两组模型的最大应力值相比差异较明显.ACTPS组固定节段与ACLP组相比,椎间活动度更小,邻近节段椎间活动度相比差异不明显;与完整组比较,ACTPS组和ACLP组整体椎间活动度在屈伸、侧屈、旋转方向上分别减小约25°、20°和8°,相应的邻近C3~4节段的椎间活动度代偿性的变化约0.3°、3°和0.1°.结论 ACTPS的生物力学稳定性优于ACLP,适用于2节段及以上颈椎前路减压后稳定性重建.与ACLP相比,ACTPS的断裂风险更低.%Objeetive To evaluate the biomechanical effects of the anterior cervical transpedicularscrew system (ACTPS), compared to the anterior cervical screw plate system (ACLP), in the subaxial cervical spine after 2-level corpectomy.Methods A verified intact finite

  16. A 10-year follow-up of transpedicular screw fixation and intervertebral autogenous posterior iliac crest bone graft or intervertebral B-Twin system in failed back surgery syndrome

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    Cincu, Rafael; Lorente, Francisco de Asis; Gomez, Joaquin; Eiras, Jose; Agrawal, Amit

    2015-01-01

    Background: The spine surgeons have been combining anterior and posterolateral fusion (circumferential fusion) as the final solution to treat spinal disorders and many have been using it to treat failed back surgery syndrome (FBSS). In present study, we analyzed and compared the clinical and radiological outcomes in patients with transpedicular screw fixation and intervertebral autogenous posterior iliac crest bone graft or in patients with transpedicular screw fixation and intervertebral B-Twin system for FBSS with a follow-up period of 10 years after the surgery. Materials and Methods: This study was a retrospective case study performed on 55 patients with FBSS. Clinical and radiological changes were compared between the two groups of patients on the basis of improvement of back pain, radicular pain, and work capacity. Outcome was measured in terms of Oswestry Low Back Pain Disability Index, and the changes in pain and function were documented every year from before surgery until 2012. We analyzed the evolution of 55 cases of FBSS those underwent segmental circumferential posterior fusions from June 2001 to February 2003, operated by a single surgeon and followed up during 10 years until February 2012. The patients were divided into 2 groups: In 25 patients, posterolateral fusions with Legacy™ (Medtronic, Inc. NYSE: MDT) screws and intersomatic autogenous posterior iliac crest bone graft was performed, and, in 30 patients, posterolateral fusions with the same screws and intersomatic fusion B-Twin (Biomet Spain Orthopaedics, S.L.) system was performed. In all cases, we used posterior lumbar interbody fusion (PLIF)/transforaminal lumbar interbody fusion (TLIF) approach for intervertebral graft, and the artrodesis was supplemented at intertransverse level with Autologus Growth Factor (AGF-MBA INCORPORADO, S.A.). The outcome was measured in terms of Oswestry Low Back Pain Disability Index, and the changes in pain and function were documented every year and compared

  17. C2~3椎弓根-侧块螺钉系统治疗不稳定型Hangman骨折%Transpedicular with Pedicle Screw Fixation for the Treatment of Hangman's Fractures

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    王磊; 刘海龙; 徐卫松; 仇志学; 韩国栋

    2011-01-01

    目的 探讨C2~3椎弓根-侧块螺钉系统治疗Hangman骨折的疗效及临床效果.方法 我院2007年4月至2010年10月收治的11例Hangman骨折患者进行回顾性研究,男4例,女7例;年龄22~61岁,平均42.5岁.患者均表现为颈痛、颈部活动受限,2例单侧上肢,1例双侧上肢麻木无力.所有患者入院后均行X线、三维CT及MRI检查,并测量Cz~3椎体移位和成角,其中Levine- Edwards分型,Ⅰ型3例,Ⅰ型4例,Ⅰa型2倒,Ⅲ型2例.人院后常规行颅骨牵引,Ⅰ型患者予以halo-vest架外固定治疗,Ⅱ型、Ⅱa型、Ⅲ型患者行后路C2~3椎弓根侧块螺钉内固定术,术后用费城颈托保护6周.结果 随访2~44个月,平均20.6个月.平均6个月时骨折端愈合,颈痛、肢体麻木等症状消失,但颈部活动度较正常略有下降,无内固定失败及感染等并发症发生.结论 经后路C2~3椎弓根侧块螺钉系统是治疗Hangman骨折的良好手术方式.%Objective To determine the treatment efficacy of transpedicular with pedicle screw fixation for the treatment of Hangman's fracture. Methods A retrospective review of 11 cases,including 4 males and 7 females,with Hangman's fractures was performed. The age of the patients were 22~61 years, average 42. 5 years. All the patients complained neck pain and limitation of movement of the neck. Numbness and weakness appeard in unilateral upper limb in 2 cases, biliater upper limbs in 1 case. All patients received anterior-posterior and lateral X-rays,MRI andthree dimensional CT scans. Initial and final radiographs were measured for translation and angilation of C2~J. According to the Levine-Edwards classification,there were 3 cases for type I ,4 for type H ,2 for type JI a and 2 for type I . Skull tractions under extension position were used in all patients after admission. Halo-vest treatment option for type Ⅰ ,Then type Ⅱ ,Ⅱla, Ⅲ transpedicular with pedicle screw fixation were performed. Philadelphia collars

  18. Robot-assisted Anterior Odontoid Screw Fixation: A Case Report.

    Science.gov (United States)

    Tian, Wei; Wang, Han; Liu, Ya-Jun

    2016-08-01

    Anterior odontoid screw fixation has been proved to be effective but technically challenging because the difficult approach is associated with high risks of screw malposition and damage to surrounding vital structures. Navigation techniques are therefore increasingly being used to improve safety and accuracy. However, no robot-assisted odontoid screw fixation has yet been reported. We here report a 61-year-old woman with a type II dens fracture on whom anterior odontoid screw fixation was performed under the guidance of a newly developed robotic system (TiRobot, co-designed by Beijing Jishuitan Hospital and TINAVI Medical Technologies). One odontoid screw was safely and accurately placed, the calculated deviation between the planned and actual positions being 0.9 mm. No intraoperative complications were identified and the patient was discharged on Day 5. Follow-up studies after 2 weeks showed good clinical and radiological results. We believe this is the first reported case of robot-assisted anterior odontoid screw fixation. We consider that complicated procedures can become feasible, safe and accurate using TiRobot systems.

  19. Application of C2 Transpedicular Screw Fixation Combined with C3 Lateral Mass Screw Plate Fixation in Posterior Treatment of Old Hangman's Fracture%经后路C2椎弓根C3侧块短节段固定治疗陈旧性枢椎椎弓骨折

    Institute of Scientific and Technical Information of China (English)

    曹成刚; 梁益建; 何睿; 石化洋; 曾勇; 陈伶

    2012-01-01

    Objective To approach the therapeutic effect of C2 transpedicular screw fixation combined with C3 lateral mass screw plate fixation on old Hangman' s fracture. Methods Nine patients with old Hangman' s fracture were treated with C2 transpedicular screw fixation combined with C3 lateral mass screw plate fixation as well as bone gr'aft fusion in our hospital from 2002. Results A mean follow-up time was 8 months(6 to 15 months). All cases got bony union. No infection, neurological deficits, or other complications were found. Conclusion It can be an effective and simple way to treat old Hangman' s fracture with C2 transpedicular screw fixation combined with C3 lateral mass screw plate fixation, which can ultimately preserve the cervical function.%目的 探讨经后路C2椎弓根C3侧块短节段内固定治疗陈旧性枢椎椎弓骨折(Hangman骨折)的疗效.方法 2002年以来9例陈旧性Hangman骨折采用经后路C2椎弓根C3侧块短节段固定,植骨融合治疗.结果 所有患者随访6~15个月,平均8个月.所有患者均骨性愈合,未出现感染、神经损伤等并发症.结论 经后路C2椎弓根C3侧块短节段内固定治疗陈旧性Hangman骨折是一种安全有效并能最大程度保留患者颈部功能的方法.

  20. Bony healing of unstable thoracolumbar burst fractures in the elderly using percutaneously applied titanium mesh cages and a transpedicular fixation system with expandable screws.

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    Anica Eschler

    Full Text Available There is a high incidence of vertebral burst fractures following low velocity trauma in the elderly. Treatment of unstable vertebral burst fractures using the same principles like in stable vertebral burst fractures may show less favourable results in terms of fracture reduction, maintenance of reduction and cement leakage. In order to address these shortcomings this study introduces cementless fixation of unstable vertebral burst fractures using internal fixators and expandable intravertebral titanium mesh cages in a one-stage procedure via minimum-invasive techniques.A total of 16 consecutive patients (median age 76 years, range 58-94 with unstable thoracolumbar burst fractures and concomitant osteoporosis were treated by an internal fixator inserted via minimum invasive technique one level above and below the fractured vertebra. Fracture reduction was achieved and maintained by transpedicular placement of two titanium mesh cages into the fractured vertebral body during the same procedure. Intra- and postoperative safety of the procedure as well as analysis of reduction quality was analysed by 3D C-arm imaging or CT, respectively. Clinical and radiographic follow-up averaged 10.4 months (range 4.5-24.5.Stabilization of the collapsed vertebral body was achieved in all 16 cases without any intraoperative complication. Surgical time averaged 102 ± 6.6 minutes (71-194. The postoperative kyphotic angle (KA and Cobb angle revealed significant improvements (KA 13.7° to 7.4°, p < 0.001; Cobb 9.6° to 6.0°, p < 0.002 with partial loss of reduction at final follow-up (KA 8.3°, Cobb 8.7°. VAS (Visual Analogue Scale improved from 7.6 to 2.6 (p < 0.001. Adjacent fractures were not observed. One minor (malposition of pedicle screw complication was encountered.Cementless fixation of osteoporotic burst fractures revealed substantial pain relief, adequate maintenance of reduction and a low complication rate. Bony healing after unstable osteoporotic burst

  1. Evaluation of Outcome of Transpedicular Decompression and Instrumented Fusion in Thoracic and Thoracolumbar Tuberculosis

    Science.gov (United States)

    Jain, R.K.; Kiyawat, Vivek

    2017-01-01

    Study Design Retrospective analysis. Purpose We evaluated the functional, neurological, and radiological outcome in patients with thoracic and thoracolumbar tuberculosis operated through the transpedicular approach. Overview of Literature For surgical treatment of thoracic and thoracolumbar tuberculosis, the anterior approach has been the most popular because it allows direct access to the infected tissue, thereby providing good decompression. However, anterior fixation is not strong, and graft failure and loss of correction are frequent complications. The transpedicular approach allows circumferential decompression of neural elements along with three-column fixation attained via pedicle screws by the same approach. Methods A total of 47 patients were diagnosed with tuberculosis of the thoracic or thoracolumbar region from August 2012 to August 2013. Of these, 28 patients had progressive neurological deterioration or increasing back pain despite conservative measures and underwent transpedicular decompression and pedicle screw fixation with posterior fusion. Antituberculosis therapy was given till signs of radiological healing were evident (9–16 months). Functional outcome (visual analog scale [VAS] score for back pain), neurological recovery (Frankel grading), and radiological improvement were evaluated preoperatively, immediate postoperatively, and at 3 months, 6 months, and 1 year. Results Mean VAS score for back pain improved from 8.7 preoperatively to 1.1 at 1 year follow-up. Frankel grading preoperatively was grade B in 7, grade C in 11, and Grade D in 10 patients, which improved to grade D in 6 and grade E in 22 patients at the last follow-up. Radiological healing was evident in the form of reappearance of trabeculae formation, resolution of pus, fatty marrow replacement, and bony fusion in all patients. Mean correction of segmental kyphosis postoperatively was 10.5°. Mean loss of correction at final follow-up was 4.1°. Conclusions Transpedicular

  2. Anatomic Study of Anterior Transdiscal Axial Screw Fixation for Subaxial Cervical Spine Injuries.

    Science.gov (United States)

    Ji, Wei; Zheng, Minghui; Qu, Dongbin; Zou, Lin; Chen, Yongquan; Chen, Jianting; Zhu, Qingan

    2016-08-01

    Anterior transdiscal axial screw (ATAS) fixation is an alternative or supplement to the plate and screw constructs for the upper cervical spine injury. However, no existing literatures clarified the anatomic feasibility of this technique for subaxial cervical spine. Therefore, the objective of this study was to evaluate the anatomical feasibility and to establish guidelines for the use of the ATAS fixation for the subaxial cervical spine injury.Fifty normal cervical spines had radiographs to determine the proposed screw trajectory (the screw length and insertion angle) and the interbody graft-related parameters (the disc height and depth, and the distance between anterior vertebral margin and the screw) for all levels of the subaxial cervical spine. Following screw insertion in 8 preserved human cadaver specimens, surgical simulation and dissection verified the feasibility and safety of the ATAS fixation.Radiographic measurements showed the mean axial screw length and cephalic incline angle of all levels were 41.2 mm and 25.2°, respectively. The suitable depth of the interbody graft was >11.7 mm (the distance between anterior vertebral margin and the screw), but C2-C3, C3-C4, C4-C5, and C5-C6 levels, but impossible at C6-C7 due to the obstacle of the sternum. All screws were placed accurately. None of the screws penetrated into the spinal canal and caused fractures determined by dissecting the specimens.The anterior transdiscal axial screw fixation, as an alternative or supplementary instrumentation for subaxial cervical spine injuries, is feasible and safe with meticulous surgical planning.

  3. Transpedicular screw fixation system for treatment of unstable fractures of arias vertebra%经后路单纯寰椎椎弓根螺钉内固定治疗不稳定性寰椎骨折

    Institute of Scientific and Technical Information of China (English)

    马维虎; 许楠健; 徐荣明; 赵刘军; 蒋伟宇; 孙韶华; 胡勇; 刘观燚; 顾勇杰

    2011-01-01

    目的 探讨经后路单纯寰椎椎弓根螺钉内固定治疗不稳定性寰椎骨折的临床疗效.方法 2007年3月~2010年4月,采用经后路寰椎椎弓根螺钉内固定治疗不稳定性寰椎骨折患者23例,其中8例为后3/4 Jefferson骨折;12例患者为半环Jefferson骨折;3例患者为后1/2 Jefferson骨折.患者均有不同程度的颈枕区疼痛,活动受限;日本骨科协会(Japanese Orthopaedic Association,JOA)评分为7~12分,平均9.5分.结果 所有患者随访12~39个月,平均18.8个月.手术时间为30~60 min,出血量为50~200 mL.术后X 线片及CT 示1例一侧寰椎椎弓根螺钉部分进入椎动脉孔,1例螺钉一侧偏内致椎弓根内侧皮质破裂,但均无神经症状,其余螺钉位置良好.术后JOA评分13~17分,平均14.7分.未发生与螺钉相关的神经血管并发症,无内固定松动或断钉现象,所有患者术后随访时均已达到骨性融合,寰枢关节旋转功能良好.结论 寰椎后路椎弓根螺钉技术是治疗不稳定性寰椎骨折的有效方法.%Objective To study the clinical outcomes of transpedicular screw fixation system for treatment of unstable fractures of the atlas vertebra. Methods From March 2007 to April 2010, transpedicular fixation was employed to treat 23 patients with unstable fractures of the atlas vertebra; the patients included l5 males and 8 females. Eight patients had posterior 3/4 Jefferson fracture, 12 had 1/2 ring Jefferson fracture and 3 had posterior 1/2 Jefferson fracture. The preoperative Japanese Orthopaedic Association(JOA) score was 7-12, with an average of 9.5. All patients were treated by single transpedicular fixation via the posterior approach. Results The patients were followed up for 12-39 months, with a mean of 18.8 months. The operative time ranged 30-60 min. Intraoperative blood loss ranged from 50-200 mL. Postoperative roentgenoghaph and CT scan showed that 1 screw was inserted so medially and penetrated the spinal canal, and 1

  4. Anterior transarticular screw fixation as a conventional operation for rigid stabilization

    Directory of Open Access Journals (Sweden)

    Manabu Sasaki

    2014-01-01

    Full Text Available Background: Anterior transarticular screw (ATS fixation is a useful surgical option for atlantoaxial (AA stabilization. This report presents a revised ATS method for AA fusion. Methods: A 79-year-old male presented with AA instability attributed both to an old odontoid fracture and severe degeneration of the lateral atlantoaxial joints (LAAJs. ATS fixation was performed through the conventional anterior cervical approach. The longest screw trajectories were planned preoperatively using multiplanar reconstruction computed tomography (CT scans, with entry points of the screws situated at the midpoint on the inferior border of the axial body. The surgical exposure was limited to opening at the entry points alone. Our retractor of choice was the Cusco speculum; it sufficiently secured space for utilizing the required instruments for screw placement while offering sufficient protection of soft tissues. Cannulated full-threaded bicortical screws stabilized the LAAJs. Screw insertion required a significant amount of coronal angulation up to the superior articular process of the atlas under open-mouth and lateral fluoroscopy image guidance. After ATS fixation, bone grafting was performed between the posterior laminae of the axis and the atlas through a conventional posterior approach. Results: Bony fusion between the atlas and the axis was confirmed radiographically. Arthrodesis of the LAAJs occurred despite no bone grafting. Conclusions: Rigid fixation of the LAAJs was obtained by our ATS technique, indicating that it is an alternative method for AA fixation when posterior rigid internal fixation is not applicable.

  5. Fixed Appliance with Expansion Screw for the Treatment of Primary Anterior Crossbite.

    Science.gov (United States)

    Paul, Sanchit; Rao, Ashwin; Chalakkal, Paul; Mony, Saranya

    2016-05-01

    Anterior crossbite occurring during the primary dentition stage needs immediate correction so that functional, aesthetic and skeletal complications may be avoided in the future. This article describes a fixed appliance with an expansion screw that was successfully used for the treatment of primary anterior crossbite. Crossbite correction was achieved in about six weeks. A detailed description with regard to fabrication of the appliance has also been discussed.

  6. Maxillary anterior en masse retraction using different antero-posterior position of mini screw: a 3D finite element study

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    Zohreh Hedayati

    2016-10-01

    Full Text Available Abstract Background Nowadays, mini screws are used in orthodontic tooth movement to obtain maximum or absolute anchorage. They have gained popularity among orthodontists for en masse retraction of anterior teeth after first premolar extraction in maximum anchorage cases. The purpose of this study was to determine the type of anterior tooth movement during the time when force was applied from different mini screw placements to the anterior power arm with various heights. Methods A finite element method was used for modeling maxillary teeth and bone structure. Brackets, wire, and hooks were also designed for modeling. Two appropriate positions for mini screw in the mesial and distal of the second premolar were designed as fixed nodes. Forces were applied from the mini screw to four different levels of anterior hook height: 0, 3, 6, and 9 mm. Initial tooth movement in eight different conditions was analyzed and calculated with ANSYS software. Results Rotation of anterior dentition was decreased with a longer anterior power arm and the mesial placement of the mini screw. Bodily movements occurred with the 9-mm height of the power arm in both mini screw positions. Intrusion or extrusion of the anterior teeth segment depended on the level of the mini screw and the edge of the power arm on the Z axis. Conclusions According to the findings of this study, the best control in the sagittal plane during anterior en masse retraction was achieved by mesial placement of the mini screw and the 9-mm height of the anterior power arm. Where control in the vertical plane was concerned, distal placement of the mini screw with the 6-mm power arm height had minimum adverse effect on anterior dentition.

  7. Experimental and Numerical Analysis of Screw Fixation in Anterior Cruciate Ligament Reconstruction

    Science.gov (United States)

    Chizari, Mahmoud; Wang, Bin; Snow, Martyn; Barrett, Mel

    2008-09-01

    This paper reports the results of an experimental and finite element analysis of tibial screw fixation in anterior cruciate ligament (ACL) reconstruction. The mechanical properties of the bone and tendon graft are obtained from experiments using porcine bone and bovine tendon. The results of the numerical study are compared with those from mechanical testing. Analysis shows that the model may be used to establish the optimum placement of the tunnel in anterior cruciate ligament reconstruction by predicting mechanical parameters such as stress, strain and displacement at regions in the tunnel wall.

  8. Experimental study on treatment of acetabular anterior column fractures: applyment of a minimally invasive percutaneous lag screw guide apparatus

    OpenAIRE

    Zhang, Li-hai; Zhang, Li-cheng; Si, Qing-hua; Gao, Yuan; Su, Xiu-Yun; Zhao, Zhe; Tang, Pei-Fu

    2016-01-01

    Background The aim of this study was to design a new minimally invasive percutaneous lag screw guide apparatus and to verify its adjuvant treatment of acetabular anterior column fracture on pelvis specimens. Methods This guide apparatus was self-developed based on the principles of “two points form a line” and “Rectangle”. Using C-arm fluoroscopy, this guide apparatus was used to conduct minimally invasive percutaneous lag screw internal fixation of acetabular anterior column fractures. Ten h...

  9. Unilateral lag-screw technique for an isolated anterior 1/4 atlas fracture

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    Semih Keskil

    2016-01-01

    Full Text Available Study Design: Fractures of the atlas are classified based on the fracture location and associated ligamentous injury. Among patients with atlas fractures treated using external immobilization, nonunion of the fracture could be seen. Objective: Ideally, treatment strategy for an unstable atlas fracture would involve limited fixation to maintain the fracture fragments in a reduced position without restricting the range of motion (ROM of the atlantoaxial and atlantooccipital joints. Summary of Background Data: Such a result can be established using either transoral limited internal fixation or limited posterior lateral mass fixation. However, due to high infection risk and technical difficulty, posterior approaches are preferred but none of these techniques can fully address anterior 1/4 atlas fractures such as in this case. Materials and Methods: A novel open and direct technique in which a unilateral lag screw was placed to reduce and stabilize a progressively widening isolated right-sided anterior 1/4 single fracture of C 1 that was initially treated with a rigid cervical collar is described. Results: Radiological studies made after the surgery showed no implant failure, good cervical alignment, and good reduction with fusion of C 1 . Conclusions: It is suggested that isolated C 1 fractures can be surgically reduced and immobilized using a lateral compression screw to allow union and maintain both C 1-0 and C 1-2 motions, and in our knowledge this is the first description of the use of a lag screw to achieve reduction of distracted anterior 1/4 fracture fragments of the C1 from a posterior approach. This technique has the potential to become a valuable adjunct to the surgeon′s armamentarium, in our opinion, only for fractures with distracted or comminuted fragments whose alignment would not be expected to significantly change with classical lateral mass screw reduction.

  10. A simplified technique for anterior cervical discectomy and fusion using a screw-plate implanted over the Caspar distractor pins.

    Science.gov (United States)

    Fransen, Patrick

    2010-08-01

    The author presents a simplified technique for midline screw-plate fixation in fusion procedures after anterior cervical discectomy, in which the plate is introduced over the Caspar distractor pins. The Uniplate system used, with a single screw in each vertebral body, minimizes bone damage to the vertebral body as the screws can be fixed in the holes previously used for the Caspar distractor pins. This simplified version of the classical anterior cervical fusion technique saves surgical time, facilitates screw insertion, and obviates the need for manipulations to stabilize the plate before the screws are inserted. It provides immediate stability comparable to other plate systems. To the author's knowledge, this is the first report on cervical fusion with the Uniplate system with the plate being introduced over the Caspar distractor pins.

  11. The Clinical Effects and Value of Surgical Treatment by Direct Transpedicular Osteo-Synthesis with Lag Screw in II Hangman,s Fracture%枢椎椎弓根拉力螺钉治疗II型Hangman骨折的疗效评价

    Institute of Scientific and Technical Information of China (English)

    陈小明; 曹奇; 杨铁军; 陈亮元; 唐国军; 颜学亮; 唐晓军

    2013-01-01

    目的:评价枢椎椎弓根拉力螺钉治疗II型Hangman骨折的临床疗效。方法对我科12例II型Hangman骨折采用双侧枢椎椎弓根拉力螺钉治疗,其中II型8例,IIa型4例,术前、术后及随访时分别评估脊髓神经功能及影像学资料。结果所有患者均获得随访,评均随访15个月(6~24月),手术平均时间65min(50~80min),无脊髓神经损伤及其他并发症,骨折均在术后3~6个月愈合,未出现螺钉断裂、松动,未见C2/3失稳及后凸畸形形成。结论枢椎椎弓根拉力螺钉能够安全、有效的治疗II型Hangman骨折。%Objective To discuss the clinical ef ects and value of surgical treatment by direct transpedicular osteosynthesis with lag screw for II Hangman,s Fracture. Method:12 patients with with acute traumatic spondylolisthesis of axis were treated by direct transpedicular osteo -synthesis with lag screw .8 patients classified as type II,4 patients classified as type IIa. Its image data and the function of spinal cord and nerves were col ected at pre-op,post-op and fol ow-up respectively. Result:Al patients were fol owed up,mean fol ow-up time is 15 months,it cost an average time of 65 minutes (50-80min)to finish the procedure. al cases gained bony fusion 3-6 months later and didn't any postoperation complicat -ions. The range of neck rotation was stored normal with no c2/3 instability、screw loosing or broking、kyphosis found. Conclusion:Transpedicular lag screw fixation can treated II Hangman,s Fracture safely and ef ectively.

  12. The Use of Posterior Short Segment Screw Fixation and Balloon Kyphoplasty in the Surgical Treatment of Traumatic Vertebral Fracture: A Case Report

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    Sevim Ondul

    2012-04-01

    Full Text Available Surgical treatments for the fracture of the spine are frequently used in clinical practice. Posterior spine stabilization with transpedicular screw fixation is one of the surgical treatment methods in the surgical treatment of spinal fractures. A 48-year old male patient was admitted to our hospital with a diagnosis of the L1 compression fracture resulting from traumatic injury. Posterior transpedicular screws were placed at one level above and one level below of the fractured vertebrate. Anterior column of the fractured vertebrate was strengthened with balloon kyphoplasty application. The system was completed with the placement of transverse rods. Fusion with allograft was performed. According to the ASIA neurological grading system, the patient was assessed as Grade E. 10 cm skin and fascia incision was done. Operation time of about 70 minutes and blood loss was less than 100 cc. The patient was mobilized on the first day of surgery and was discharged from the hospital on the third day after the surgery. Short segment transpedicular fixation on the one level above and one level below of the fractured vertebrate together with balloon kyphoplasty on the corpus of the fractured vertebrate may be used as a minimally invasive surgical treatment in such kind of injuries. The advantages are short duration of hospital stay, less blood loss, providing early mobilization, and a reliable method for fixation and stabilization. In this article, a case with traumatic fracture that fixed and stabilized with short segment transpedicular screw placement and balloon kyphoplasty application was presented.

  13. Are two retrograde 3.5 mm screws superior to one 7.3 mm screw for anterior pelvic ring fixation in bones with low bone mineral density?

    Science.gov (United States)

    Zderic, I.; Grechenig, S.; Richards, R. G.; Schmitz, P.; Gueorguiev, B.

    2017-01-01

    Objectives Osteosynthesis of anterior pubic ramus fractures using one large-diameter screw can be challenging in terms of both surgical procedure and fixation stability. Small-fragment screws have the advantage of following the pelvic cortex and being more flexible. The aim of the present study was to biomechanically compare retrograde intramedullary fixation of the superior pubic ramus using either one large- or two small-diameter screws. Materials and Methods A total of 12 human cadaveric hemipelvises were analysed in a matched pair study design. Bone mineral density of the specimens was 68 mgHA/cm3 (standard deviation (sd) 52). The anterior pelvic ring fracture was fixed with either one 7.3 mm cannulated screw (Group 1) or two 3.5 mm pelvic cortex screws (Group 2). Progressively increasing cyclic axial loading was applied through the acetabulum. Relative movements in terms of interfragmentary displacement and gap angle at the fracture site were evaluated by means of optical movement tracking. The Wilcoxon signed-rank test was applied to identify significant differences between the groups Results Initial axial construct stiffness was not significantly different between the groups (p = 0.463). Interfragmentary displacement and gap angle at the fracture site were also not statistically significantly different between the groups throughout the evaluated cycles (p ⩾ 0.249). Similarly, cycles to failure were not statistically different between Group 1 (8438, sd 6968) and Group 2 (10 213, sd 10 334), p = 0.379. Failure mode in both groups was characterised by screw cutting through the cancellous bone. Conclusion From a biomechanical point of view, pubic ramus stabilisation with either one large or two small fragment screw osteosynthesis is comparable in osteoporotic bone. However, the two-screw fixation technique is less demanding as the smaller screws deflect at the cortical margins. Cite this article: Y. P. Acklin, I. Zderic, S. Grechenig, R. G. Richards, P

  14. Accuracy and safety of pedicle screw placement in neuromuscular scoliosis with free-hand technique.

    Science.gov (United States)

    Modi, Hitesh N; Suh, Seung Woo; Fernandez, Harry; Yang, Jae Hyuk; Song, Hae-Ryong

    2008-12-01

    It is a retrospective analytic study of 1,009 transpedicular screws (689 thoracic and 320 lumbosacral), inserted with free-hand technique in neuromuscular scoliosis using postoperative CT scan. The aim of paper was to determine the accuracy and safety of transpedicular screw placement with free-hand technique in neuromuscular scoliosis and to compare the accuracy at different levels in such population. All studies regarding accuracy and safety of pedicle screw in scoliosis represent idiopathic scoliosis using various techniques such as free-hand, navigation, image intensifier, etc., for screw insertion. Anatomies of vertebrae and pedicle are distorted in scoliosis, hence accurate and safe placement of pedicle screw is prerequisite for surgery. Between 2004 and 2006, 37 consecutive patients, average age 20 years (9-44 years), of neuromuscular scoliosis were operated with posterior pedicle screw fixation using free-hand technique. Accuracy of pedicle screws was studied on postoperative CT scan. Placement up to 2 mm medial side and 4 mm lateral side was considered within-safe zone. Of the 1,009 screws, 273 screws were displaced medially, laterally or on the anterior side showing that 73% screws (68% in thoracic and 82.5% in lumbar spine) were accurately placed within pedicle. Considering the safe zone, 93.3% (942/1009, 92.4% in thoracic and 95.3% in lumbar spine) of the screws were within the safe zone. Comparing accuracy according to severity of curve, accuracy was 75% in group 1 (curve 90 degrees) with a safety of 94.8 and 91.2%, respectively (P = 0.35). Comparing the accuracy at different thoracic levels, it showed 67, 64 and 72% accuracy in upper, middle and lower thoracic levels with safety of 96.6, 89.2 and 93.1%, respectively, exhibiting no statistical significant difference (P = 0.17). Pedicle screw placement in neuromuscular scoliosis with free-hand technique is accurate and safe as other conditions.

  15. 椎弓根钉棒系统固定治疗齿状突骨折合并寰枢关节不稳%Transpedicular Screw Fixation System for the Treatment of Dens Fracture Complicated with Atlantoaxial Instability

    Institute of Scientific and Technical Information of China (English)

    张毅; 黄象望; 沈雄杰; 常磊

    2011-01-01

    [Objective]To explore the method and efficacy of transpedicular screw fixation system for the treatment of traumatic axial dentoid process fracture complicated with atlantoaxial instability.[Methods]Twenty six adult cases of acute axial dentoid process fracture complicated with atlantoaxial instability from Dec.2005 to April 2010 were reviewed.Among all the cases, 18 cases were male and 8 cases were female.According to Anderson-D' Alonzo typing method modified by Grauer, 5 cases were type Ⅱ A, and 12 cases were type Ⅱ B, and 6 cases were type Ⅱ C, and 3 cases were type Ⅲ.Three cases were accompanied by spinal injury including 2 cases with type Ⅱ B and one case with type Ⅱ C.All cases were complicated with atlantoaxial instability.At first, all the cases underwent skull traction for atlantoaxial reduction, and then were fixed with atlantoaxial pedicle screw system by cervical posterior approach under general anesthesia.Of all cases, 19 cases underwent autologous iliac bone graft and 7 cases underwent atlantoaxial pedicle screw fixation.The surgical efficacy was assessed by JOA scores before and after operation.[Results]No vertebral artery or spinal injury occurred during operation.Mean time of follow-up was 12 months(8~25 months).Cervicobrachialgia in all patients was alleviated.Three cases with spinal injury had the recovery of neurological function to some ex tent.The imaging data of all cases showed that the atlantoaxial anatomic relationship recovered well and pedicle screws were in a proper position without postoperative loosening or breaking.The bony fusion was obtained in 19 cases undergoing bone graft at 6 months of follow up.The internal fixation system was removed in 7 ca ses without bone graft after one and a half years.Atlantoaxial rotational function was restored satisfactorily.[Conclusion]Atlantoaxial pedicle screw fixation for the treatment of traumatic axial dentoid process fracture complicated with atlantoaxial instability is a solid

  16. Internal Fixation of Transverse Patella Fractures Using Cannulated Cancellous Screws with Anterior Tension Band Wiring

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    Khan I

    2016-07-01

    Full Text Available Aims: To evaluate the effectiveness and safety of anterior tension band wiring technique using two cannulated cancellous screws in patients with transverse (AO34-C1 or transverse with mildly comminuted (AO34-C2 patellar fractures. Materials and Methods: This is a prospective study of 25 patients with transverse fracture or transverse fracture with mildly comminuted patella fractures. All the patients were treated with open reduction and internal fixation using two parallel cannulated screws and 18G stainless steel wire as per the tension band principle. Results: There were eighteen males (72% and seven females (28%. The age group ranged from 24 to 58 years, with mean age of 38 years. The most common mode of injury was fall (72% followed by road traffic accident (20% and violent quadriceps contraction (8%. Transverse fracture was present in 60% and transverse fracture with mild comminution in 40% of patients. Mean time to achieve union was 10.7 weeks (range 8-12 weeks. Mean ROM at three months was 113.8 degree (90-130 and at final follow up this improved to 125.4 degrees (range 100-140. There was one case of knee stiffness and no case of implant failure was observed. Patients were evaluated using Bostman scoring, the mean score at three months being 26.04 which improved to 27.36 at the end of final follow up at one year. Conclusion: Cannulated cancellous screws with anterior tension band wiring is a safe, reliable and reproducible method in management of transverse patellar fractures, with less chances of implant failure and soft tissue irritation.

  17. Magnesium inference screw supports early graft incorporation with inhibition of graft degradation in anterior cruciate ligament reconstruction

    Science.gov (United States)

    Cheng, Pengfei; Han, Pei; Zhao, Changli; Zhang, Shaoxiang; Zhang, Xiaonong; Chai, Yimin

    2016-05-01

    Patients after anterior cruciate ligament (ACL) reconstruction surgery commonly encounters graft failure in the initial phase of rehabilitation. The inhibition of graft degradation is crucial for the successful reconstruction of the ACL. Here, we used biodegradable high-purity magnesium (HP Mg) screws in the rabbit model of ACL reconstruction with titanium (Ti) screws as a control and analyzed the graft degradation and screw corrosion using direct pull-out tests, microCT scanning, and histological and immunohistochemical staining. The most noteworthy finding was that tendon graft fixed by HP Mg screws exhibited biomechanical properties substantially superior to that by Ti screws and the relative area of collagen fiber at the tendon-bone interface was much larger in the Mg group, when severe graft degradation was identified in the histological analysis at 3 weeks. Semi-quantitative immunohistochemical results further elucidated that the MMP-13 expression significantly decreased surrounding HP Mg screws with relatively higher Collagen II expression. And HP Mg screws exhibited uniform corrosion behavior without displacement or loosening in the femoral tunnel. Therefore, our results demonstrated that Mg screw inhibited graft degradation and improved biomechanical properties of tendon graft during the early phase of graft healing and highlighted its potential in ACL reconstruction.

  18. Influence of screw length and diameter on tibial strain energy density distribution after anterior cruciate ligament reconstruction

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    Yao, Jie; Kuang, Guan-Ming; Wong, Duo Wai-Chi; Niu, Wen-Xin; Zhang, Ming; Fan, Yu-Bo

    2014-04-01

    Postoperative tunnel enlargement has been frequently reported after anterior cruciate ligament (ACL) reconstruction. Interference screw, as a surgical implant in ACL reconstruction, may influence natural loading transmission and contribute to tunnel enlargement. The aims of this study are (1) to quantify the alteration of strain energy den sity (SED) distribution after the anatomic single-bundle ACL reconstruction; and (2) to characterize the influence of screw length and diameter on the degree of the SED alteration. A validated finite element model of human knee joint was used. The screw length ranging from 20 to 30mm with screw diameter ranging from 7 to 9 mm were investigated. In the post-operative knee, the SED increased steeply at the extra-articular tunnel aperture under compressive and complex loadings, whereas the SED decreased beneath the screw shaft and nearby the intra-articular tunnel aperture. Increasing the screw length could lower the SED deprivation in the proximal part of the bone tunnel; whereas increasing either screw length or diameter could aggravate the SED deprivation in the distal part of the bone tunnel. Decreasing the elastic modulus of the screw could lower the bone SED deprivation around the screw. In consideration of both graft stability and SED alteration, a biodegradable interference screw with a long length is recommended, which could provide a beneficial mechanical environment at the distal part of the tunnel, and meanwhile decrease the bone-graft motion and synovial fluid propagation at the proximal part of the tunnel. These findings together with the clinical and histological factors could help to improve surgical outcome, and serve as a preliminary knowledge for the following study of biodegradable interference screw. [Figure not available: see fulltext.

  19. Biomechanical effects of polyaxial pedicle screw fixation on the lumbosacral segments with an anterior interbody cage support

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    Chen Hsiang-Ho

    2007-03-01

    Full Text Available Abstract Background Lumbosacral fusion is a relatively common procedure that is used in the management of an unstable spine. The anterior interbody cage has been involved to enhance the stability of a pedicle screw construct used at the lumbosacral junction. Biomechanical differences between polyaxial and monoaxial pedicle screws linked with various rod contours were investigated to analyze the respective effects on overall construct stiffness, cage strain, rod strain, and contact ratios at the vertebra-cage junction. Methods A synthetic model composed of two ultrahigh molecular weight polyethylene blocks was used with four titanium pedicle screws (two in each block and two rods fixation to build the spinal construct along with an anterior interbody cage support. For each pair of the construct fixed with polyaxial or monoaxial screws, the linked rods were set at four configurations to simulate 0°, 7°, 14°, and 21° lordosis on the sagittal plane, and a compressive load of 300 N was applied. Strain gauges were attached to the posterior surface of the cage and to the central area of the left connecting rod. Also, the contact area between the block and the cage was measured using prescale Fuji super low pressure film for compression, flexion, lateral bending and torsion tests. Results Our main findings in the experiments with an anterior interbody cage support are as follows: 1 large segmental lordosis can decrease the stiffness of monoaxial pedicle screws constructs; 2 polyaxial screws rather than monoaxial screws combined with the cage fixation provide higher compression and flexion stiffness in 21° segmental lordosis; 3 polyaxial screws enhance the contact surface of the cage in 21° segmental lordosis. Conclusion Polyaxial screws system used in conjunction with anterior cage support yields higher contact ratio, compression and flexion stiffness of spinal constructs than monoaxial screws system does in the same model when the spinal segment

  20. Monoaxial Pedicle Screws Are Superior to Polyaxial Pedicle Screws and the Two Pin External Fixator for Subcutaneous Anterior Pelvic Fixation in a Biomechanical Analysis

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    Rahul Vaidya

    2013-01-01

    Full Text Available Purpose. Comparison of monoaxial and polyaxial screws with the use of subcutaneous anterior pelvic fixation. Methods. Four different groups each having 5 constructs were tested in distraction within the elastic range. Once that was completed, 3 components were tested in torsion within the elastic range, 2 to torsional failure and 3 in distraction until failure. Results. The pedicle screw systems showed higher stiffness (4.008 ± 0.113 Nmm monoaxial, 3.638 ± 0.108 Nmm Click-x; 3.634 ± 0.147 Nmm Pangea than the exfix system (2.882 ± 0.054 Nmm in distraction. In failure testing, monoaxial pedicle screw system was stronger (360 N than exfixes (160 N and polyaxial devices which failed if distracted greater than 4 cm (157 N Click-x or 138 N Pangea. The exfix had higher peak torque and torsional stiffness than all pedicle systems. In torsion, the yield strengths were the same for all constructs. Conclusion. The infix device constructed with polyaxial or monoaxial pedicle screws is stiffer than the 2 pin external fixator in distraction testing. In extreme cases, the use of reinforcement or monoaxial systems which do not fail even at 360 N is a better option. In torsional testing, the 2 pin external fixator is stiffer than the pedicle screw systems.

  1. Application of posterior Moss-Miami transpedicular system for the treatment of adolescent idiopathic scoliosis

    Institute of Scientific and Technical Information of China (English)

    ZHU Xiao-dong; LI Ming; ZHANG Qi; HOU Tie-sheng; HE Shi-sheng

    2007-01-01

    Objective:To determine the effectiveness of posterior Moss-Miami transpedicular system for the treatment of adolescent idiopathic scoliosis in 24 patients with a 2-year minimum follow up. Methods:24 patients who underwent operations between September 2002 and November 2003 were evaluated for curve correction, spinal balance, and complications. Age at surgery averaged 13.8 years (range from 10 to20). The spinal deformities were evaluated by Cobb method with anteroposterior and lateral bending radiographs. All patients were right thoracic curves. Posterior instrumentation (Moss-Miami transpedicular system) was used. The transpedicular screws were placed between T2 and L2. All the patients were assessed both clinically and radiographically. Follow-up averaged 2.8 years. Results: There was an average correction of 72% of the primary curve (pre-operation standing average 54 degrees (range from 40 to 67degrees), post-operation average 15.2 degrees (range from 2 to 27 degrees), at last examination average 16.1 degrees (range from 2 to 30 degrees). Infection and neurological complications were not noted. No major complications were observed. Conclusions: Frontal and sagittal thoracic curve correction of thoracic scoliosis can be satisfactorily obtained using Moss Miami transpedicular instrumentation. It seems that control of the three columns of the spine by the transpedicular screws offers sufficient apical translation and coronal realignment.

  2. The clinical research of posterior transpedicular screw fixation combined with intervertebral bone grafting fusion in the treatment of Ⅱ degree and Ⅲ degree lumbar spondylolisthesis%后路椎弓根螺钉内固定联合椎间植骨融合治疗Ⅱ、Ⅲ度腰椎滑脱的临床研究

    Institute of Scientific and Technical Information of China (English)

    宁凯; 车立新; 王志刚; 李坤; 吉喆

    2012-01-01

    目的 探讨后路椎弓根螺钉内固定联合椎间植骨融合治疗Ⅱ、Ⅲ度腰椎滑脱临床疗效.方法 回顾性分析我院2009年1月~2011年1月收治入院的30例腰椎滑脱症患者临床资料,所有病例均为Ⅱ、Ⅲ度腰椎滑脱.患者均采用后路椎弓根螺钉内固定联合椎间植骨融合治疗,观察手术前后临床症状及滑脱恢复情况、术后复位、疗效评价、材料生物相容性、术后椎间隙高度及BFS评分.结果 30例患者术前均为Ⅱ、Ⅲ度腰椎滑脱,其中,19例行椎管、神经根管减压、复位固定、植骨融合治疗,11例只行复位固定、植骨融合治疗.获得随访30例,均超过12个月.30例椎间植骨全部融合,融合率为100%.BFS评分优良率达90.0%.结论 后路椎弓根螺钉内固定联合椎间植骨融合治疗Ⅱ、Ⅲ度腰椎滑脱,操作简便、固定可靠,是临床治疗中的一种值得推广的方法.%Objective To explore the curative effect of posterior transpedicular screw fixation combined with intervertebral bone grafting fusion in the treatment of Ⅱ degree and Ⅲ degree lumbar spondylolisthesis. Methods The clinical data of 30 patients with lumbar spondylolisthesis from January 2009 to January 2011 in our hospital were analyzed retrospectively. All cases were suffered with Ⅱ degree or Ⅲ degree lumbar spondylolisthesis. All patients were adopted posterior transpedicular screw fixation combined with intervertebral bone grafting fusion treatment. The clinical symptoms, slippage recovery condition before and after operation, postoperative restoration, therapeutic effect evaluation, material biocompatibility, postoperative intervertebral height and BFS score were observed. Results 30 patients all suffered with Ⅱ degree or Ⅲ degree lumbar spondylolisthesis before surgery, among whom 19 cases were treated with canalis vertebralis and nerve root canal decompression, reduction and fixation and bone graft fusion. Other 11 cases were

  3. Insertion of lower cervical spine anterior pedicle screw in 18 cadavers%下颈椎前路椎弓根螺钉置入的实验研究

    Institute of Scientific and Technical Information of China (English)

    王远政; 刘洋; 邓忠良

    2012-01-01

    目的 探讨下颈椎前路椎弓根螺钉置入技术的可行性.方法 取18具成人尸体正常颈椎标本,剔除其周围软组织至清楚显露椎体前壁.CT扫描后,用Mimics软件重建三维模型,并测量C3~C7个体化置钉参数,包括进钉点(即椎弓根中轴线在椎体前壁投影点)、置钉方向(螺钉在横断面和矢状面上的倾斜角度)以及螺钉长度.严格按照测量结果,直视下置入椎弓根螺钉.术后作CT扫描,评价置钉效果.结果 进针点:C3、C4位于置钉椎弓根对侧,正中矢状面旁2~3 mm,距上终板6~7 mm;C5~ C7与置钉椎弓根同侧,其中C5位于正中矢状面旁1~2 mm,距上终板7.0~7.5 mm,C6、C7则为4~5 mm和7.5 ~8.5 mm.置钉方向:理想角度在C3、C4为外倾角46°~47°,头倾角-11°~-7°;在C5外倾角约48°,头倾角接近0°;C6、C7为36°~40°和8~13°.螺钉长度:可选择28、30、32 mm,其直径为3.5 mm.本组共置钉144枚.术后CT示,全部螺钉均经椎体前方置入椎弓根内抵达侧块.其中,有16枚胀破椎弓根外侧皮质,3枚穿破外侧皮质(均发生在C3、C4节段).结论 下颈椎前路椎弓根螺钉置入技术是可行的.%Objective To study the feasibility of lower cervical spine anterior pedicle screw ( APS) insertion and provide basis for its clinical application according to the preoperative APS related technological parameters. Methods Normal cervical spine specimens of 18 cadavers were carefully dissected to resect the surrounding tissue and to clearly expose the centrum antetheca. Following the CT scans, three dimensional model was reconstructed by Mimics software. The imaging data to measured key parameters of anterior transpedicular screw fixation were also produced by Mimics software. The individual screw insertion parameters including intersection point (projective point of pedicle central axis on the centrum antetheca) , insertion angle (the inclined angle of screws in cross-sectional and sagittal

  4. Comparison of Isocentric C-Arm 3-Dimensional Navigation and Conventional Fluoroscopy for Percutaneous Retrograde Screwing for Anterior Column Fracture of Acetabulum: An Observational Study.

    Science.gov (United States)

    He, Jiliang; Tan, Guoqing; Zhou, Dongsheng; Sun, Liang; Li, Qinghu; Yang, Yongliang; Liu, Ping

    2016-01-01

    Percutaneous screw insertion for minimally displaced or reducible acetabular fracture using x-ray fluoroscopy and computer-assisted navigation system has been advocated by some authors. The purpose of this study was to compare intraoperative conditions and clinical results between isocentric C-arm 3-dimensional (Iso-C 3D) fluoroscopy and conventional fluoroscopy for percutaneous retrograde screwing of acetabular anterior column fracture.A prospective cohort study was conducted. A total of 22 patients were assigned to 2 different groups: 10 patients in the Iso-C 3D navigation group and 12 patients in the conventional group. The operative time, fluoroscopic time, time of screw insertion, blood loss, and accuracy were analyzed between the 2 groups.There were significant differences in operative time, screw insertion time, fluoroscopy time, and mean blood loss between the 2 groups. Totally 2 of 12 (16.7%) screws were misplaced in the conventional fluoroscopy group, and all 10 screws were in safe zones in the navigation group. Percutaneous screw fixation using the Iso-C 3D computer-assisted navigation system significantly reduced the intraoperative fluoroscopy time and blood loss in percutaneous screwing for acetabular anterior column fracture.The Iso-C 3D computer-assisted navigation system provided a reliable and effective method for percutaneous screw insertion in acetabular anterior column fractures compared to conventional fluoroscopy.

  5. Improved Accuracy and Safety of Intracorporeal Transpedicular Bone Grafting - using Contrast Impregnated Bone: A Case Report

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    CK Chiu

    2014-11-01

    Full Text Available A method of transpedicular bone grafting using contrast impregnated bone to improve the visualization of bone graft on the image intensifier is reported. A - 36-year old man who had sustained traumatic burst fracture of T12 vertebra, with Load-Sharing Classification (LSC score of 8, was treated with posterior short segment fusion from T11 to L1 with transpedicular bone graft of T12 vertebra. We were able to correct the kyphotic end plate angle (EPA from 19º to 1.4º. Anterior bone graft augmentation was achieved with contrast enhaced transpedicular bone grafts. At six months follow up, CT scan showed good bony integration of the anterior column with EPA of 4.5º and two years later, radiographs showed EPA of 7.6 º.

  6. Biodegradable Magnesium Screws Accelerate Fibrous Tissue Mineralization at the Tendon-Bone Insertion in Anterior Cruciate Ligament Reconstruction Model of Rabbit

    Science.gov (United States)

    Wang, Jiali; Xu, Jiankun; Fu, Weimin; Cheng, Wenxiang; Chan, Kaiming; Yung, Patrick Shu-hang; Qin, Ling

    2017-01-01

    The incorporation of tendon graft into bone tunnel is one of the most challenging clinical issues in anterior cruciate ligament (ACL) reconstruction. As a biodegradable metal, Mg has appropriate mechanical strength and osteoinductive effects, thus may be a promising alternative to commercialized products used for graft fixation. Therefore, it was hypothesized that Mg based interference screws would promote tendon graft-bone junction healing when compared to Ti screws. Herein, we compared the effects of Mg and Ti screws on tendon graft healing in rabbits with ACL reconstruction via histological, HR-pQCT and mechanical analysis. The histological results indicated that Mg screws significantly improved the graft healing quality via promoting mineralization at the tendon graft enthesis. Besides, Mg screws significantly promoted bone formation in the peri-screw region at the early healing stage. Importantly, Mg screws exhibited excellent corrosion resistance and the degradation of Mg screws did not induce bone tunnel widening. In tensile testing, there were no significant differences in the load to failure, stress, stiffness and absorption energy between Mg and Ti groups due to the failure mode at the midsubstance. Our findings demonstrate that Mg screws can promote tendon graft healing after ACL reconstruction, implying a potential alternative to Ti screws for clinical applications. PMID:28071744

  7. Evaluation of soft tissues around single tooth implants in the anterior maxilla restored with cemented and screw-retained crowns.

    Science.gov (United States)

    Cutrim, Emerson Souza; Peruzzo, Daiane Cristina; Benatti, Bruno

    2012-12-01

    Implant-supported restorations can be attached as screw-retained or cemented prostheses. In both situations, the characteristics of the soft tissues around the implants are crucial for oral rehabilitation and patient satisfaction. Therefore, this study uses the Pink Esthetic Score (PES), which allows evaluation of gingival esthetics around implants, to evaluate the soft tissues around implants in the anterior maxilla rehabilitated with cemented prostheses (CP) and screw-retained prostheses (SP). Forty implants placed in the anterior maxilla were evaluated, and these had been rehabilitated with prosthetic crowns for a minimum of 1 year. Periodontal examination was performed to evaluate probing depth (PD) and bleeding on probing (BOP) of the implant and the corresponding natural tooth. The total mean (±SD) PES for SP was 10.73 (±1.98) and 10.41 (±2.67) for CP, which was not statistically significant (P ≥ .05). Periodontal examination revealed that CP and SP showed no difference for BOP (P ≥ .05). Differences were only detected in PD when comparing the reference teeth of both groups to CP and SP (P ≤ .05). The present study demonstrates that the PES proved to be an efficient index to assess peri-implant tissues, and that the type of crown retention does not influence the health and quality of the soft tissues around implants.

  8. 肌间隙入路、椎弓根椎体内植骨结合骨折椎螺钉治疗胸腰椎骨折%The treatment of chest lumbar vertebra bone fracture by muscle gap approach with vertebral transpedicular grafting the bone union bone vertebral fractures screws

    Institute of Scientific and Technical Information of China (English)

    王桥贵

    2016-01-01

    目的:探讨胸腰段脊柱肌间隙后入路(muscle gap approach,MGA)经椎弓根植骨(transpedicular grafting,TPG)和结合骨折椎螺钉(vertebral fractures screws,VFS )治疗胸腰段脊柱骨折的方法和疗效。方法对30例胸腰椎骨折患者经MGA, TPG,VFS,后路短节段椎弓根内固定手术,记录手术时间、失血量、住院时间。在术前,术后及末次随访时测量伤椎前缘高度与正常高度的比值、后凸Cobb角,末次随访的过伸过屈位X线片上测量手术节段运动范围,了解神经功能改变及腰背疼痛变化,功能评定采用Greenough腰痛评分。结果随访15-38个月(平均22.3个月),平均手术时间:130min,平均失血量362ml,平均住院时间15d。术前平均Cobb角360,椎体平均相对高度降低48.8%,术后平均Cobb角2.30,术后椎体相对高度降低≤6.2%。末次随访平均Cobb角矫正丢失2.50,椎体相对高度矫正丢失2.3%。无断钉及内固定物松动,无供骨区并发症。结论肌间隙入路椎弓根椎体内植骨结合骨折椎螺钉治疗胸腰椎骨折,疗效满意。具有失血量少,保留手术节段运动范围,无供骨区并发症。最大可能保留后柱完整性,增强胸腰椎骨折后路短节段内固定的牢固性,利于矫正后凸畸形和维持矫正效果。%Objective This discussion aims at the methods and treatment of the chest waist section spinal column bone fracture through chest waist section spinal column muscle gap approach with the bone transpedicular grafting(TPG)and the union bone vertebral fractures screws(VFS).Methods 30 cases were conducted an operation on the chest waist section spinal column bone fracture by MGA, TPG,VFS and the fixed surgery in the rear guard short stage vertebral arch root. The surgery time,the amount of blood loss,the time of treatment in hospital were recorded. It should be learned that the ratio of the injury front height and

  9. Interference screw versus Endoscrew fixation for anterior cruciate ligament reconstruction: A biomechanical comparative study in sawbones and porcine knees

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    Chu-Chih Hung

    2014-04-01

    Full Text Available Interference screw fixation is one of the most common methods for ligament reconstruction. Although the advantages and clinical outcomes of this procedure have been widely reported, post-surgical complications often arise. The purpose of this study was to evaluate a new femoral fixation device, the Endoscrew, for anterior cruciate ligament (ACL reconstruction. We performed a mechanical test in accordance with American Society for Testing and Materials (ASTM standards and an in vitro biomechanical study. An axial pullout test was conducted to evaluate the mechanical properties of the new device and the interference screw when implanted in solid rigid polyurethane foam test blocks. The biomechanical test used porcine femora to evaluate the initial fixation strength between these two implants. The maximum pullout force of the interference screw group [722.05 ± 130.49 N (N] was significantly greater (p < 0.01 than the Endoscrew group (440.79 ± 26.54 N when implanted in polyurethane foam 320 kg/m3 density. With polyurethane foam 160 kg/m3 density, the maximum pullout forces were (242.61 ± 37.36 N (p < 0.001 and (99.33 ± 30.01 N for the interference screw group and Endoscrew group, respectively. In the in vitro mechanical study, the Endoscrew (646.39 ± 72.38 N required a significantly greater ultimate load prior to failure (p < 0.05 when compared with the interference screw (489.72 ± 138.64 N. With regard to pullout stiffness, there was no statistically significant difference (p < 0.13 between the Endoscrew group (99.15 ± 12.16 N/mm and the interference screw group (87.96 ± 11.12 N/mm. The cyclic stiffness was also not significantly different (p < 0.44 between the Endoscrew group (93.09 ± 16.07 N/mm and the interference screw group (85.78 ± 14.76 N/mm. The axial pullout test showed that the strength of the Endoscrew was close to the fixation strength required for daily activities, but it is

  10. One-stage posterior C2 and C3 pedicle screw fixation or combined anterior C2-C3 fusion for the treatment of unstable hangman's fracture.

    Science.gov (United States)

    Liu, Jingchen; Li, Ye; Wu, Yuntao

    2013-03-01

    The present study aimed to evaluate the effect of using one-stage posterior C2 and C3 pedicle screw fixation or combined anterior C2-C3 fusion in the treatment of unstable hangman's fracture. A total of 13 patients with unstable hangman's fractures underwent C2 and C3 pedicle screw fixation, lamina interbody fusion or combined anterior C2-C3 fusion and imaging examinations to evaluate the fracture fixation and healing condition at three days and three months following surgery. Postoperative X-ray and computed tomography (CT) results showed high fracture reduction, good internal fixation position and reliable fracture fixation. The three-month postoperative CT showed good vertebral fracture healing. C2 and C3 pedicle screw fixation has a good curative effect in the treatment of unstable hangman's fracture. The direct fixation of the fracture enables early ambulation by the patients.

  11. Anterior single odontoid screw placement for type II odontoid fractures: our modified surgical technique and initial results in a cohort study of 15 patients

    Science.gov (United States)

    Munakomi, Sunil; Tamrakar, Karuna; Chaudhary, Pramod Kumar; Bhattarai, Binod

    2016-01-01

    Objective: Anterior odontoid screw fixation for type II odontoid fracture is the ideal management option. However in the context of unavailability of an O-arm or neuro-navigation and poor images from the available C-arm may be an obstacle to ideal trajectory and placement of the odontoid screw. We herein detail  our surgical technique so as to ensure a correct trajectory and subsequent good fusion in Type II odontoid fractures. This may be advantageous  in clinical set ups lacking state of the art facilities.  Methods and Results: In this cohort study we included 15 consecutive patients who underwent anterior odontoid screw placement. We routinely dissect the longus colli to completely visualize the entire width of C3 body. We then perform a median C2-C3 disectomy followed by creating a gutter in the superior end of C3 body. We then guide the Kirchsner (K) wire purchasing adequate anterior cortex of C2. Rest of the procedure follows the similar steps as described for odontoid screw placement. We achieved 100% correct trajectory and screw placement in our study. There were no instances of screw break out, pull out or nonunion. There was one patient mortality following myocardial infarction in our study. Conclusion: Preoperative imaging details, proper patient positioning, meticulous dissection, thorough anatomical knowledge and few added surgical nuances are the cornerstones in ideal odontoid screw placement. This may be pivotal in managing  patients in developing nations having rudimentary neurosurgical set up. PMID:27990259

  12. Delayed anterior cervical plate dislodgement with pharyngeal wall perforation and oral extrusion of cervical plate screw after 8 years: A very rare complication

    Directory of Open Access Journals (Sweden)

    Ravindranath Kapu

    2012-01-01

    Full Text Available We report a patient with congenital anomaly of cervical spine, who presented with clinical features suggestive of cervical compressive spondylotic myelopathy. He underwent C3 median corpectomy, graft placement, and stabilization from C2 to C4 vertebral bodies. Postoperative period was uneventful and he improved in his symptoms. Eight years later, he presented with a difficulty in swallowing and occasional regurgitation of feeds of 2 months duration and oral extrusion of screw while having food. On oral examination, there was a defect in the posterior pharyngeal wall through which the upper end of plate with intact self-locking screw and socket of missed fixation screw was seen. This was confirmed on X-ray cervical spine. He underwent removal of the plate system and was fed through nasogastric tube and managed with appropriate antibiotics. This case is presented to report a very rare complication of anterior cervical plate fixation in the form of very late-onset dislodgement, migration of anterior cervical plate, and oral extrusion of screw through perforated posterior pharyngeal wall.

  13. External transpedicular spine fixation in severe spondylodiscitis – salvage procedure

    Directory of Open Access Journals (Sweden)

    Spalteholz, Matthias

    2013-11-01

    Full Text Available Specific and non-specific infections of the spine are rare. Due to their potential for severe instabilities, deformities and the impairment of neurological structures, the treatment is often prolonged and needs an interdisciplinary management. The clinical presentation is uncharacteristic, therefore diagnosis is often delayed. There are no prospective randomized studies for therapy recommendation. The surgical concept includes eradication of the infection and the reliable stabilization of involved segments. This concept is successful in most cases of endogenous vertebral osteomyelitis. The therapy of the exogenous spine infections after macro and micro surgery is more difficult, due to the critical wound situation and the involvement of the posterior parts of the spine. In these cases, infection-associated instability of the anterior part is complicated by critical posterior wound conditions.We present three cases of severe exogenous vertebral infections, where temporary external transpedicular spine fixation was used for salvage procedure, till soft tissue conditions have permitted a definitive internal stabilization.

  14. Magnetic resonance imaging analysis of the bioabsorbable Milagro interference screw for graft fixation in anterior cruciate ligament reconstruction.

    Science.gov (United States)

    Frosch, K-H; Sawallich, T; Schütze, G; Losch, A; Walde, T; Balcarek, P; Konietschke, F; Stürmer, K M

    2009-10-01

    Ligament graft fixation with bioabsorbable interference screws is a standard procedure in cruciate ligament replacement. Previous screw designs may resorb incompletely, and can cause osteolysis and sterile cysts despite being implanted for several years. The aim of this study was to examine the in vivo degradation and biocompatibility of the new Milagro interference screw (Mitek, Norderstedt, Germany). The Milagro interference screw is made of 30% ss-TCP (TriCalcium phosphate) and 70% PLGA (Poly-lactic-co-glycolic acid). In the period between June 2005 and February 2006, 38 patients underwent graft fixation with Milagro screws in our hospital. Arthroscopic ACL reconstruction was performed using hamstring tendon grafts in all the patients. MR imaging was performed on 12 randomly selected patients out of the total of 38 at 3, 6 and 12 months after surgery. During the examination, the volume loss of the screw, tunnel enlargement, presence of osteolysis, fluid lines, edema and postoperative screw replacement by bone tissue were evaluated. There was no edema or signs of inflammation around the bone tunnels. At 3, 6 and 12 months, the tibial screws showed an average volume loss of 0, 8.1% (+/-7.9%) and 82.6% (+/-17.2%, P Milagro screw is closely linked to the graft healing process. The screws were rapidly resorbed after 6 months and, at 12 months, only the screw remnants were detectable. Moreover, the Milagro screw is biocompatible and osteoconductive, promoting bone ingrowth during resorption. Tunnel enlargement is not prevented in the first months but is reduced by bone ingrowth after 12 months.

  15. FUNCTIONAL RESULTS OF SURGICAL TREATMENT FOR ISTHMIC SPONDYLOLISTHESIS USING ANTERIOR AND POSTERIOR EXPOSURES

    Directory of Open Access Journals (Sweden)

    V. V. Rudenko

    2013-01-01

    Full Text Available Objective - to compare results of spondylolisthesis treatment using different surgical technologies. Material and methods: 84 patients (aged from 19 till 67 with spondylolisthesis of 1-3 degree (H.W Meyerding were operated. Two methods of surgical exposures were used for decompression and stabilization. Anterior decompression and stabilization exposures from retroperitoneal access were used for the first group of patients. The second group was operated using posteriolateral interbody fusion with transpedicular screw fixation. The following results were estimated after operation: the level of patients’ postoperative adaptation period and the rate of neurological and orthopedic rehabilitation during the postoperative period. Conclusions. The obtained functional results show no difference for both groups where posterior and anterior exposures were used for spondylolisthesis surgical treatment of 1-3 degree.

  16. DLC screw preload. Loosening prevention

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    Ivete Aparecida de Mattias Sartori

    2008-01-01

    Full Text Available The screw loosening is a reason to prosthetic rehabilitation failure. However, the DLC (Diamond-like carbon screw treatment lead thefriction decrease and sliding between the components, which increases the screw preload benefit and decreases the chance of looseningoccurrence. This case shows a clinical indication of the association of the correct preload applied and the DLC screw, which can be considered an optimized protocol to solve screw loosening recidivate of unitary prosthesis in anterior maxillary site.

  17. One-stage posterior C2 and C3 pedicle screw fixation or combined anterior C2-C3 fusion for the treatment of unstable hangman’s fracture

    OpenAIRE

    Liu, Jingchen; Li, Ye; Wu, Yuntao

    2013-01-01

    The present study aimed to evaluate the effect of using one-stage posterior C2 and C3 pedicle screw fixation or combined anterior C2-C3 fusion in the treatment of unstable hangman’s fracture. A total of 13 patients with unstable hangman’s fractures underwent C2 and C3 pedicle screw fixation, lamina interbody fusion or combined anterior C2-C3 fusion and imaging examinations to evaluate the fracture fixation and healing condition at three days and three months following surgery. Postoperative X...

  18. 经一侧伤椎短节段椎弓根固定联合椎体内植骨治疗胸腰段椎体骨折%Short-segment pedicle screw fixation with screw placed at single injured vertebrae combined with transpedicular intracorporeal grafting for thoracolumbar fractures

    Institute of Scientific and Technical Information of China (English)

    许天明; 徐永清; 陈建明; 张成程; 李勇; 李占清; 刘山林; 文景

    2012-01-01

    Objective To explore the clinical value of subtotal corpectomy of spinal anterior median vertebral column and three column reconstruction through posterior approach in treatment of severe thoracolumbar bursting fracture. Methods Totally 36 patients with severe thoracolumbar bursting fracture were treated with the technique of subtotal corpectomy of anterior median spinal vertebral column and three column reconstruction through posterior approach. Spinal cord injuries were evaluated with ASIA grade criterion. Reduction, decompression and fusion of fractures were assessed by evaluation of the anterior vertebral compression ratio, Cobb angle for local kyphosis and sagittal diameter of injured vertebral spinal canal encroachment ratio before and after operation and at the time of last follow -up. Results Hemopneumothorax and cerebrospinal fluid leakage respectively occurred in one patient and were treated successfully. The average follow-up duration was 17.8 months. Nervous function improved in different degree in all patients except those patients who had the nervous function of grade A. The anterior vertebral compression ratio, Cobb angle for local kyphosis and sagittal diameter of injured vertebral spinal canal encroachment ratio after operation and at the time of last follow-up were more significant than before operation (P 0.05). Conclusion The operation has the advantages of less injury, fewer complications, thorough spinal cord decompression, effectively recovering the stability of the three-column spine, avoiding loss of resetting and rupture of internal fixation. It is an ideal operation method for the treatment of thoracolumbar bursting fracture.%目的 探讨经一侧伤椎短节段椎弓根固定联合椎体内植骨治疗胸腰段椎体骨折的可行性及疗效.方法 将自2005年1月~2009年5月行短节段椎弓根钉固定联合椎体内植骨治疗的102例胸腰段椎体骨折随机分为两组.A组行后路短节段椎弓根钉固定结合经

  19. Influência do macheamento do orifício piloto nos parafusos cervicais anteriores Influencia del taladramiento del agujero piloto en tornillos cervicales anteriores Influence of tapping the pilot hole in anterior cervical screws

    Directory of Open Access Journals (Sweden)

    Patrícia Silva

    2013-01-01

    de 3,5 mm, y en el lado izquierdo el implante fue colocado sin el taladramiento del agujero piloto. Se realizaron ensayos mecánicos para evaluar la fuerza de retirada y el estudio histomorfométrico de la interfase hueso-implante en la fase aguda y ocho semanas después de la colocación del implante. El torque de inserción se midió durante la colocación del implante. RESULTADOS: La fuerza de torsión de la inserción y la resistencia a la extracción fueron más altas en los implantes colocados sin el taladramiento del agujero piloto. La interfaz hueso-implante presentó mayor área de contacto con el hueso y mayor área de hueso dentro de la rosca del implante en los tornillos implantados sin taladramiento previo. No se observaron diferencias en el hueso fuera del paso de la rosca del implante. CONCLUSIONES: El taladramiento del agujero piloto reduce el par de torsión de inserción y la resistencia a la extracción del implante en las fases aguda y crónica, y reduce el área de contacto hueso-implante y el área ósea en el interior del paso de la rosca.OBJECTIVE: Experimentally analyze the influence of the pilot hole tapping on the mechanical properties and the bone-implant interface of anterior cervical screw. METHODS: Eight shorn Santa Inês sheep were used in the study. In cervical segments C2-C7 of the column 2.5mm pilot holes were made on both sides of the vertebra. On the right side of the vertebra tapping was done before the insertion of the cortical screw of 3.5mm, and on the left side the implant was placed without tapping the pilot hole. Mechanical assays were performed to assess the strength of pullout as well as a histomorphometric study of bone-implant interface during the acute phase and eight weeks after implant placement. The insertion torque was measured during implant placement. RESULTS: The insertion torque and pullout strength were higher for implants placed without tapping the pilot hole. The bone-implant interface showed greater area of

  20. Immediate placement and loading of implants in anterior maxilla using an altered screw-retained implant fixed prosthesis

    Directory of Open Access Journals (Sweden)

    Baig Mirza

    2010-01-01

    Full Text Available This article describes the immediate placement and loading of implants in the aesthetic zone using an implant-retained, fixed prosthesis with a modified design. One section of the implant prosthesis has cemented crowns and the other section is the conventional screw-retained. This combined approach significantly offsets the unsuitable implant position, alignment or angulation, while ensuring the easy retrievability, repair and maintenance of the prosthesis at the same time.

  1. Anterior subaxial cervical spine fixation using a plate with single screw per vertebral body: A simple and efficient construct - Clinical series and a cadaver study

    Directory of Open Access Journals (Sweden)

    Vannemreddy Prasad

    2009-01-01

    Full Text Available Objective: To report our experience with a novel construct for traumatic and nontraumatic cervical spine lesions that was validated by biomechanical studies of cadaver cervical spine. Study Design: Consecutive cases of anterior cervical spine fixation performed over six years reviewed for stability offered by a construct comprising of a plate fixed by a single screw to each vertebral body. Setting: A university hospital and a biomechanical lab. Materials and Methods: Data were coded and entered into a statistical worksheet for multivariate analysis. Cadaver spine models applied for biomechanical study of stability. Results: Total of 103 cases reviewed; 86 with single-level disease; traumatic in 66 (64% cases and degenerative in 33 (32% cases, including hard disks, OPLL, and spondylitis (4% with other causes. Fixation was with diskectomy in 59 and with corpectomy in 40. A bone graft was utilized for fusion in 87 and a bone-filled titanium spacer in 13. A single screw was placed in each vertebral body with a locking plate (having linear arrangement of holes. This construct remained strong in 95% of cases at the end of 6-24 months. Five cases failed requiring reoperation. Five patients with cervical spinal cord injury (SCI died. On statistical analysis, construct was stronger with diskectomy compared with corpectomy. Construct used on cadavers confirmed the biomechanical stability in short segment fixation (C5-6. Conclusion: A conservative construct utilizing a single screw per vertebral body and a one-holed plate system appears to be strong enough to afford stability in both traumatic and nontraumatic lesions of subaxial cervical spine, comparable to others.

  2. Anterior single odontoid screw placement for type II odontoid fractures: our modified surgical technique and initial results in a cohort study of 15 patients [version 2; referees: 2 approved

    Directory of Open Access Journals (Sweden)

    Sunil Munakomi

    2016-11-01

    Full Text Available Objective: Anterior odontoid screw fixation for type II odontoid fracture is the ideal management option. However in the context of unavailability of an O-arm or neuro-navigation and poor images from the available C-arm may be an obstacle to ideal trajectory and placement of the odontoid screw. We herein detail  our surgical technique so as to ensure a correct trajectory and subsequent good fusion in Type II odontoid fractures. This may be advantageous  in clinical set ups lacking state of the art facilities.  Methods and Results: In this cohort study we included 15 consecutive patients who underwent anterior odontoid screw placement. We routinely dissect the longus colli to completely visualize the entire width of C3 body. We then perform a median C2-C3 disectomy followed by creating a gutter in the superior end of C3 body. We then guide the Kirchsner (K wire purchasing adequate anterior cortex of C2. Rest of the procedure follows the similar steps as described for odontoid screw placement. We achieved 100% correct trajectory and screw placement in our study. There were no instances of screw break out, pull out or nonunion. There was one patient mortality following myocardial infarction in our study. Conclusion: Preoperative imaging details, proper patient positioning, meticulous dissection, thorough anatomical knowledge and few added surgical nuances are the cornerstones in ideal odontoid screw placement. This may be pivotal in managing  patients in developing nations having rudimentary neurosurgical set up.

  3. Anterior subcutaneous fixation with screw-rod internal fixator for the treatment of unstable anterior pelvic ring fractures%经皮钉-棒内支架治疗不稳定骨盆前环骨折

    Institute of Scientific and Technical Information of China (English)

    王朝晖; 何波涌; 曾敏川; 郭建辉; 唐艳平; 赵快平; 刘建伟

    2016-01-01

    目的探讨经皮钉-棒内支架治疗不稳定骨盆前环骨折临床应用。方法回顾性分析经皮钉-棒内支架治疗的12例不稳定骨盆前环骨折患者的临床资料,男性8例,女性4例;年龄23~63岁,平均43.8岁。骨盆骨折按照Tile分类:B34例,C14例,C23例,C31例。后环损伤采用经皮骶髂螺钉固定2例,髂腰固定1例,钢板固定6例,其中M张力带钢板固定4例。结果前环固定平均出血70mL(50~90mL),平均手术时间65min(50~85min)。单侧股外侧皮神经损伤5例,均恢复正常;随访4~15个月,无切口感染、内固定失效等,骨折均获骨性愈合,疗效满意。结论经皮钉-棒内支架是治疗不稳定骨盆前环骨折微创舒适、简便、安全的方法,疗效好,但术中应警惕股外侧皮神经损伤。%Objective To study percutaneous internal fixation with screw-rod system for the treatment of unstable anterior pelvic ring fractures .Methods The clinical data of 12 cases of unstable anterior pelvic ring frac-tures treated with anterior subcutaneous fixation with screw-rod system was retrospectively analyzed . According to the Tile’s classification,4 cases were B3,4 cases were C1,3 cases were C2,and 1 case was C3.In all these poste-rior ring fractures,2 cases were treated with percutaneous iliosacral screw fixation ,1 case with ilio-lumbar fixation,and 6 cases with plate fixation (including M-shaped tension plate fixation in 4 cases).Results The average blood loss and operation time of anterior pelvic ring fixation were 70 mL ( ranged from 50 to 90 mL) and 65 min( ranged from 50 to 85min)respectively.Unilateral lateral femoral cutaneous nerves were inpaired in 5 cases and the symptoms resolved after 2 weeks.All cases were followed up for 4 to 15 months,indicating bone healing and satisfactory clinical results , without wound infection or fixation failure .Conclusion The percutaneous internal fixation with screw-rod system

  4. Simultaneous anterior and posterior screw fixations confined to the axis for stabilization of a 3-part fracture of the axis (odontoid, dens, and hangman fractures): report of 2 cases.

    Science.gov (United States)

    Shinbo, Jun; Sameda, Hiroaki; Ikenoue, Sumio; Takase, Kan; Yamaguchi, Takeshi; Hashimoto, Eiko; Enomoto, Takahiro; Kanazuka, Aya; Mimura, Masaya

    2014-03-01

    Fractures of the axis are considered to be one of the most common injuries to the cervical spine, accounting for more than 20% of all cervical spine fractures. Multiple fractures of the axis are much rarer, accounting for 1% of all cervical fractures. Management of such complex fractures is still challenging, and there is no strong consensus for the treatment. The authors describe the cases of 2 patients who presented with 3-part fractures of the axis consisting of an odontoid Type II fracture and a Levine-Edwards Type IA fracture, which were treated with concurrent insertion of an anterior odontoid screw and bilateral posterior pedicle screws. The cases presented were characterized by 1) a Type II odontoid fracture; 2) a Type IA traumatic spondylolisthesis with no or a little translation and angulation of C-2 on C-3 in a ring fracture of the axis; and 3) no disorders at the C2-3 disc on MR images. Therefore, the authors performed surgery confined to the axis by concurrently inserting an anterior odontoid screw and posterior bilateral pedicle screws without arthrodesis of C2-3. This was followed with cervical soft collar fixation for only 1-2 weeks. The outcomes were favorable, including good osteosynthesis, high primary stability, early patient mobilization, and preserved range of motion of the cervical spine at C2-3 as well as at C1-2.

  5. 三维重建虚拟置钉指导前路寰枢椎侧方关节螺钉内固定和齿状突螺钉内固定:3D打印模型的实验研究%Using simulated screw trajectories in three dimensional reconstruction to guide anterior C1-C2 transarticular screw fixation and odontoid screw fixation in 3D printed models

    Institute of Scientific and Technical Information of China (English)

    翁万青; 田乃锋; 王鉴顺; 王胜; 王向阳; 徐华梓; 吴爱悯; 池永龙

    2016-01-01

    目的 探讨术前运用3D打印模型进行三维重建虚拟置钉指导前路寰枢椎侧方关节螺钉和齿状突螺钉内固定的可行性. 方法 对30例正常成人的寰枢椎CT数据进行三维重建并打印骨骼模型.首先模拟前路寰枢椎侧方关节螺钉内固定术,测量最内侧方角度、最外侧方角度,取平均值为侧偏角;最小向后角度、最大向后角度,取平均值为后偏角.再次模拟齿状突螺钉内固定术,测量侧偏角、后偏角.以三维虚拟置钉结果为参考,指导三维打印模型实验置钉,分别测量前路寰枢椎侧方关节螺钉、齿状突螺钉的侧偏角和后偏角,侧偏角和后偏角,与对应的影像学数据进行对比. 结果 前路寰枢椎侧方关节螺钉内固定术三维重建虚拟置钉测得左、右侧侧偏角平均分别为21.80°±3.97°、21.54°±4.04°,后偏角平均分别为29.34°±4.48°、28.90°±4.49°.在3D打印模型中实验置钉测得左、右侧侧偏角分别为21.18°±4.95°、20.69°±4.40°,后偏角平均分别为28.88°±4.84°、28.22°±4.48°.齿状突螺钉内固定术三维虚拟置钉测得侧偏角和后偏角平均分别为0.40°±0.86°、27.16°±3.38°.在3D打印模型中实验置钉测得侧偏角和后偏角平均分别为0.24°±0.85°、27.52°±3.64°.对比分析发现三维重建模型置钉数据与相应的3D打印模型实验置钉数据基本相近,差异均无统计学意义(P>0.05). 结论 术前运用3D打印模型可以进行CT三维重建模拟精确置钉指导前路寰枢椎相应的螺钉和齿状突螺钉内固定.这种术前模拟实验手术可以作为教学和临床应用参考.%Objective To provide a preoperative protocol for surgeons by investigating the optimal screw trajectories in 3D images to guide the internal fixation with anterior atlantoaxial transarticular screws and anterior odontoid screws in 3D printed models of upper cervical spine.Methods Computed tomography (CT) scans of 30 adult

  6. Thoracolumbar spinal fractures : radiological results of transpedicular fixation combined with transpedicular cancellous bone graft and posterior fusion in 183 patients

    NARCIS (Netherlands)

    Leferink, VJM; Zimmerman, KW; Veldhuis, EFM; ten Vergert, EM; ten Duis, HJ

    2001-01-01

    In internal posterior fixation of thoracolumbar fractures combined with transpedicular cancellous bone graft and posterior fusion of the intervertebral facet joints at the level of the destroyed end plate it is still uncertain as to whether significant vertebral body collapse and loss of correction

  7. Evaluation of surgical strategy of conventional vs. percutaneous robot-assisted spinal trans-pedicular instrumentation in spondylodiscitis.

    Science.gov (United States)

    Keric, Naureen; Eum, David J; Afghanyar, Feroz; Rachwal-Czyzewicz, Izabela; Renovanz, Mirjam; Conrad, Jens; Wesp, Dominik M A; Kantelhardt, Sven R; Giese, Alf

    2017-03-01

    Robot-assisted percutaneous insertion of pedicle screws is a recent technique demonstrating high accuracy. The optimal treatment for spondylodiscitis is still a matter of debate. We performed a retrospective cohort study on surgical patients treated with pedicle screw/rod placement alone without the application of intervertebral cages. In this collective, we compare conventional open to a further minimalized percutaneous robot-assisted spinal instrumentation, avoiding a direct contact of implants and infectious focus. 90 records and CT scans of patients treated by dorsal transpedicular instrumentation of the infected segments with and without decompression and antibiotic therapy were analysed for clinical and radiological outcome parameters. 24 patients were treated by free-hand fluoroscopy-guided surgery (121 screws), and 66 patients were treated by percutaneous robot-assisted spinal instrumentation (341 screws). Accurate screw placement was confirmed in 90 % of robot-assisted and 73.5 % of free-hand placed screws. Implant revision due to misplacement was necessary in 4.95 % of the free-hand group compared to 0.58 % in the robot-assisted group. The average intraoperative X-ray exposure per case was 0.94 ± 1.04 min in the free-hand group vs. 0.4 ± 0.16 min in the percutaneous group (p = 0.000). Intraoperative adverse events were observed in 12.5 % of free-hand placed pedicle screws and 6.1 % of robot robot-assisted screws. The mean postoperative hospital stay in the free-hand group was 18.1 ± 12.9 days, and in percutaneous group, 13.8 ± 5.6 days (p = 0.012). This study demonstrates that the robot-guided insertion of pedicle screws is a safe and effective procedure in lumbar and thoracic spondylodiscitis with higher accuracy of implant placement, lower radiation dose, and decreased complication rates. Percutaneous spinal dorsal instrumentation seems to be sufficient to treat lumbar and thoracic spondylodiscitis.

  8. 片段弓技术结合上颌微螺钉支抗矫治前牙拥挤%Treatment of anterior crowding with maxillary mini-screw anchorage and class Ⅲ elastic traction

    Institute of Scientific and Technical Information of China (English)

    李正明; 刘新强; 黄永谦; 肖芦靖

    2012-01-01

    目的:评价应用片段弓技术结合上颌微螺钉支抗配合Ⅲ类颌间牵引非拔牙矫治单纯前牙拥挤的临床效果.方法:12例单纯前牙拥挤病例,应用片段弓技术,上颌颧下嵴微螺钉支抗配合Ⅲ类牵引拉后牙段向远中,待间隙足够时排齐前牙,对矫治前后的模型及X线头颅侧位片进行测量分析.结果:U1/SN、U1/NA、L1/NB和IMPA均无明显变化,结论:后牙片段弓结合上颌微螺钉支抗可以在保持前牙唇倾度不变甚至轻度内收的情况下排齐拥挤的牙列.%Objective: To evaluate the clinical effects of maxillary mini-screw anchorage and ClassⅢ elastics on non-extraction treatment of anterior crowding. Method: 12 cases of anterior crowding were treated with segmental arch technique and Mini-screws were inserted into the maxillary infrazygomatic crest (IZC) area to pull the posterior segment distally, class Ⅲ traction was used to the distal movement of mandibular posterior teeth. Anterior teeth were aligned until adequate space of front segment was obtained. Model and cephalometric X ray film were examined before and after treatment. Result: The width of upper and lower arch was increased significantly. No significant changes were seen on the angles of Ul / SN, Ul / NA.L1 / NB and IMPA. Conclusion:To those anterior crowding cases.application of segmental arch technique combination with maxillary micro-screw anchorage and Class Ⅲ traction can correct the crowing when the torque of anterior teeth was maintained. The method is suitable for mild to moderate skeletal type I crowding cases.

  9. The study of anterior cervical pedicle screw channel in the lower cervical spine%下颈椎前路椎弓根螺钉内固定解剖学测量及临床应用

    Institute of Scientific and Technical Information of China (English)

    徐荣明; 赵刘军; 马维虎; 朱彦昭

    2011-01-01

    Objective To investigate application of the anterior cervical pedicle screw in the lower cervical spine.Methods Twenty disarticulated human vertebrae (C3-C7) were evaluated with computed tomography for pedicle morphometry Parameters included vertebral body height,vertebral body depth,vertebral body width,outer pedicle width,outer pedicle height,pedicle axis length,transverse section angle,sagittal section angle,transverse intersection point distance and sagittal intersection point distance.On the basis of these data,the screw channel was determined and the screws were inserted in the specimen.Five patients underwent surgical reconstruction using anterior pedicle screw fixation.After surgery,physical examination and roentgenograms and CT scans were performed in all patients.Results The transverse section angle increased from C3(45.7°±4.0°) to C5(52.1°±5.9° ),but decreased from C6(47.8°±6.7°) to C7(44.4°± 8.3°).The sagittal section angle gradually increased from C3 (93.4°±7.2°) to C6( 112.1°±6.2°) but decreased a little to C7(102.7°±8.5°).The distances in transverse section was about 1.97-3.98 mm and in sagittal section was 3.4-7.5 mm.Anterior pedicle screws were inserted successfully in all specimens without critical pedicle wall perforations.Patients were permitted to ambulate the next day after surgery with a cervical collar.Postoperative neurological improvement was observed in all cases.Postoperative radiographic evaluation confirmed proper insertion of anterior pedicle screws without pedicle perforaton.The average follow-up time was 10.6 months.No anterior pedicle screw breakage and loosening was observed.Conclusion The entry point in anterior pedicle screw should located in 5mm to upper endplate and near anterior median line.The transverse section angle should be 45.7°-52.1°and the sagittal section angle should be 93.4°-112.1°.The lengths of the screw should be about 32 mm.%目的 通过解剖学测量和临床应用,探讨下颈椎

  10. Replacement of missing anterior tooth using screw retained implant prosthesis in the esthetic zone: a case report with 3 years of follow up.

    Science.gov (United States)

    Ahmad, Manawar; Dhanasekar, B; Aparna, I N; Naim, Hina

    2014-09-01

    As more and more dental practitioners are focusing on implant-supported fixed restorations, some clinicians favor the use of cement retained restorations while others consider screw-retained prosthesis to be the best choice. As both types of prostheses have certain advantages and disadvantages, clinicians should be aware of the limitations of each type. Screw-retained implant restorations have an advantage of predictable retention, retrievability and lack of potentially retained sub-gingival cement. However, a few disadvantages exist such as precise placement of the implant for optimal and esthetic location of the screw access hole and obtaining passive fit. On the other hand, cement retained restorations eliminates unaesthetic screw access holes; have passive fit of castings; reduce stress to splinted implants because of minor misfit of the framework; reduced complexity of lab procedures; enhanced esthetics; reduced cost factors and non disrupted morphology of the occlusal table. This case report presents the replacement of missing left central incisor using screw-retained implant prosthesis due to palatal trajectory of the implant placement and inadequate abutment height for retention of cement retained prosthesis.

  11. Clinical Observation of Anterior Single Screw on the Treatment of Old Odontoid Fractures of Anderson Type%前路单枚螺钉治疗老年齿状突 AndersonⅡ型骨折的疗效观察

    Institute of Scientific and Technical Information of China (English)

    秦双安; 张建福

    2014-01-01

    To investigate effect of the anterior single hollow screw internal fixation technique for the treatment of old odontoid fractures of Anderson type. Methods:Elderly patients with fixation in the perspective of descending anterior single screw in 23 cases of odontoid Anderson Ⅱ fracture,all the patients underwent skull traction reduction,the implantation in single screw,postoperative cervical immobilization. Results:Patients were followed up for 6 - 23 months,2 cases in the last follow-up has not yet reached bone union,5 ca-ses in 3 months after the treatment,the fracture has healed,10 cases in 5 months after the treatment showed bone union,6 cases after 1 years follow-up bone healing. Conclusion:Good stability of fixation in the treatment of elderly patients with Anderson type Ⅱ odontoid fracture of anterior single screw,atlantoaxial joint motion function was reserved,high rate of fracture healing,less complications.%目的:探讨颈前路单枚中空螺钉内固定技术治疗老年齿状突 AndersonⅡ型骨折临床疗效。方法:对23例齿状突 Ander-sonⅡ型骨折老年患者在透视下行颈前路单枚螺钉内固定术,所有患者术前行颅骨牵引复位,术中植入单枚螺钉,术后颈托外固定。结果:术后随访6~23个月,2例于最后随访仍未达到骨性愈合,5例于术后3个月复查骨折已达骨性愈合,10例于术后5个月复查时显示骨性愈合,6例于术后1 a 复查骨性愈合。结论:前路单枚螺钉内固定治疗老年 AndersonⅡ型齿状突骨折具有良好的稳定性,保留了寰枢关节运动功能,骨折愈合率较高,并发症低。

  12. 关节镜下空心螺钉固定ACL胫骨止点撕脱骨折%Treatment of anterior cruciate ligament tibial eminence avulsionfractures with hollow screw through arthroscopy

    Institute of Scientific and Technical Information of China (English)

    李云华; 刘春磊; 王贵清; 王湘江; 邹华

    2013-01-01

    Objective To observe the clinical effect of treatment of anterior cruciate ligament tibial eminence avulsion fractures with hollow screw through arthroscopy.Method 13 cases with anterior cruciate ligament tibial eminence avulsion fractures were treated through arthroscopy from February 2010 to March 2011.Fractures were reduction and fixed with hollow screw through arthroscopy.All the cases were followed-up more than 1 year.The evaluation of knee function was taken with Lysholm score system.Result All the cases were followed-up with mean time 16months (12~25months).The preoperative Lysholm scores ranged from 23 to 65,with a mean of (48.45±5.23),and the postoperative Lysholm scores ranged from 83 to 96,with a mean of (91.34±6.53).11 cases were excellent,1 good and 1 fair,the excellent and good rate was 92.3%.Conclusion It is an effiective method in the treatment of anterior cruciate ligament tibial eminence avulsion fractures with hollow screw through arthroscopy.it may produce less trauma and with quick healing.%目的 观察关节镜下空心螺钉固定ACL胫骨止点撕脱骨折的临床效果.方法 2010年2月~2011年3月,关节镜下空心螺钉固定ACL胫骨止点撕脱骨折13例,在关节镜下复位骨折块,空心螺钉固定骨折块.通过1年以上随访行疗效评定.患者膝关节功能以Lysholm评分系统评分.结果 全部病例获完整随访,平均随访16m(12~25m).Lysholm膝关节功能评分:术前23~65分,平均(48.45±5.23)分;术后83~96分,平均(91.34±6.53)分.优11例,良1例,中1例,优良率92.3%.结论 关节镜下空心螺钉固定ACL胫骨止点撕脱骨折创伤小、恢复快,是一种可行的方法.

  13. Skipping Posterior Dynamic Transpedicular Stabilization for Distant Segment Degenerative Disease

    Directory of Open Access Journals (Sweden)

    Bilgehan Solmaz

    2012-01-01

    Full Text Available Objective. To date, there is still no consensus on the treatment of spinal degenerative disease. Current surgical techniques to manage painful spinal disorders are imperfect. In this paper, we aimed to evaluate the prospective results of posterior transpedicular dynamic stabilization, a novel surgical approach that skips the segments that do not produce pain. This technique has been proven biomechanically and radiologically in spinal degenerative diseases. Methods. A prospective study of 18 patients averaging 54.94 years of age with distant spinal segment degenerative disease. Indications consisted of degenerative disc disease (57%, herniated nucleus pulposus (50%, spinal stenosis (14.28%, degenerative spondylolisthesis (14.28%, and foraminal stenosis (7.1%. The Oswestry Low-Back Pain Disability Questionnaire and visual analog scale (VAS for pain were recorded preoperatively and at the third and twelfth postoperative months. Results. Both the Oswestry and VAS scores showed significant improvement postoperatively (P<0.05. We observed complications in one patient who had spinal epidural hematoma. Conclusion. We recommend skipping posterior transpedicular dynamic stabilization for surgical treatment of distant segment spinal degenerative disease.

  14. Analysis of safety and effect of reconstructing anterior and middle columns by single posterior approach in treating lumbar burst fractures

    Institute of Scientific and Technical Information of China (English)

    ZHANG Jing-wei; XIAO Bai-ping; XU Rong-ming; ZHAO Liu-jun; MA Wei-hu; RUAN Yong-ping

    2009-01-01

    Objective: To explore the safety and effect of the technique of reconstructing anterior and middle columns by posterior approach in treating lumbar burst fractures.Methods: From July 2005 to January 2007,22 cases (18 males and 4 females,aged 28-57 years,42.7years on average) of lumbar burst fractures were treated with surgical procedures in our hospital.Based on the routine posterior approach,one of the transverse processes of the injured vertebra was incised to get access to the lateral side of the injured vetebralbody.After all the displaced fracture fragments were cleared away and the spinal canal was decompressed,the titanium mesh packed with autografts was implanted from the lateral side to reconstruct the anterior and middle columns.The adjacent above and below segments of the vetebral body were fixed with transpedicular screws.The operation time,intraoperative blood loss,vertebral height,degree of kyphotic deformity and comprised spinal canal were documented.Results: The average operation time was 3.5 hours (ranging 2.8-5.8 hours) and the average blood loss was 820 ml (ranging 650-2 100 ml).All the cases were followed up for 17.2 months on average (ranging 12-28 months).The height of the injured vetebral body was restored from 24% (12%-45%) preoperatively to 96% (95%-99%) postoperatively (P<0.05).The natural spinal curvatures and spinal canal were restored.Three cases were involved in transient iatrogenic nerve root injury and 1 case was involved in the loosening of the connected rod of the pedicle screw system 3 months postoperatively.Conclusions: The technique of implanting the titanium mesh by posterior approach is effective and safe enough to reconstruct the anterior and middle columns in treating lumbar burst fractures.

  15. 下颈椎前路椎弓根螺钉配套钢板系统的生物力学性能研究%Biomechanical characteristics of anterior pedicle screw-plate system in the lower cervical spine

    Institute of Scientific and Technical Information of China (English)

    赵刘军; 柴波; 蒋伟宇; 徐荣明; 祁峰

    2014-01-01

    目的 探讨下颈椎前路椎弓根螺钉配套钢板系统在颈椎病患者的生物力学性能.方法 采集新鲜颈椎标本16具,分解为C3/4、C4/5、C5/6、C6/7共32个运动节段(FSU),其中C3/4、C4/5、C5/6、C6/7各8个.将其按照不同节段随机分成A、B两组,将所获标本椎间盘切除后模拟植骨、分别植入我们自行设计生产的下颈椎前路椎弓根螺钉配套钢板系统和普通颈椎前路椎体螺钉钢板系统,比较两组固定系统的生物力学性能:(1)两组下颈椎三维生理运动范围(ROM);(2)两组稳定性指数;(3)两组螺钉的抗拔出力.结果 A、B两组各有16个FSU(其中C3/4、C4/5、C5/6、C6/7节段各4个),A组植入下颈椎前路椎弓根螺钉配套钢板系统16套,B组植入普通颈椎前路椎体螺钉钢板系统16套.经生物力学测试发现:(1)A组固定的颈椎节段前屈/后伸平均运动值为(12.78±1.32)°,左右侧弯(9.25±0.94)°,左右旋转(22.82 ±2.42)°;而B组分别为(16.24±1.64)、(12.08±1.32)、(28.44± 2.78)°.A组优于B组,差异有统计学意义(P<0.05).(2)A组稳定性指数(Sf)在屈伸、侧屈、旋转时分别为111%、110%、112%,而B组分别为87%、84%和88%,两者比较差异有统计学意义(P<0.05).(3)抗拔出力测试结果显示,A组最大抗拔出力为(604.68±48.76)N,而B组为(488.24±32.42)N,A组优于B组,两者比较差异有统计学意义(P<0.05).结论 下颈椎前路椎弓根螺钉配套钢板系统在生物力学性能方面优于普通颈椎前路椎体螺钉钢板系统,适用于需要颈椎前路坚强固定的患者.%Objective To explore the biomechanical characteristics of anterior pedicle screw-plate system in the lower cervical spine,and to provide basic data for clinical application.Methods Sixteen fresh cervical cadavers were collected and dissected into 32 different FSUs (8 separately in C3/4,C4/5,C5/6,and C6/7).After disectomy and intervertebral body bone graft,the subjects were randomly

  16. Ipsilateral pedicle screw placement with contralateral percutaneous facet screws: Early results with an alternative in lumbar arthrodesis

    Directory of Open Access Journals (Sweden)

    Richard B Rhiew

    2009-03-01

    Full Text Available Richard B Rhiew, Sunil Manjila, Andrew M Lozen, David Hong, Murali Guthikonda, S S RengacharyDepartment of Neurosurgery, Wayne State University, Detroit, MI, USAAbstract: Transforaminal lumbar interbody fusion (TLIF is a widely used method of surgical treatment for a variety of lumbar spinal disorders. Bilateral transpedicular instrumentation is routinely used in conjunction with an interbody graft to provide additional stability. In this technical note, we describe our fusion construct using ipsilateral pedicle screw placement on the side of TLIF and contralateral facet screw placement. We performed this construct at six levels in four patients. Suggested advantages include: low morbidity, small incision and lower cost. Outcomes parameters included radiographic evidence of solid union at four months and improvement in Oswestry Disability Index. A mean improvement from a preoperative score of 73 to 26 after surgery was observed at one-year follow-up. There were no instrument-related complications. In conclusion, this hybrid screw system minimizes contralateral dissection and is an attractive alternative to standard bilateral pedicle screw fixation.Keywords: TLIF, facet screw, pedicle screw, lumbar spine fusion

  17. 数字化仿真技术在髋臼前柱安全置钉的研究%The study of safe lag screw placement in the anterior column of acetabulum by the digital simulation technique

    Institute of Scientific and Technical Information of China (English)

    李佳兵; 项舟

    2016-01-01

    目的:利用数字化仿真技术求解髋臼前柱的安全置钉通道。方法通过将48例正常成人骨盆CT图像导入Mimics15.0中进行数字化处理得到96例髋臼前柱阴模模型,结合立体解析几何求解髋臼前柱的安全置钉通道。结果安全置钉通道:最大半径男性为(4.65±0.54)mm,女性为(3.71±1.68) mm;进钉深度男性为(114.91±6.52)mm,女性为(102.97±6.24)mm;进钉最狭窄处位于髋臼前壁内,最狭窄处到顺行进钉点的距离:男性为(34.57±2.16)mm,女性为(29.82±1.94)mm;最狭窄处到逆行进钉点的距离:男性为(73.32±3.27)mm,女性为(69.49±2.52)mm;螺钉与水平面夹角男性为(45.22±1.54)°,女性为(43.59±3.24)°;螺钉与矢状面夹角男性为(41.65±5.37)°,女性为(47.82±4.12)°;螺钉与冠状面夹角男性为(18.71±2.36)°,女性为(19.23±2.49)°。安全进钉通道参数男女对比“最大半径”、“进钉深度”、“螺钉与矢状面夹角”有统计学意义(P<0.05)。结论利用数字化仿真技术能够精确求解髋臼前柱安全置钉通道。%Objective To find and measure the safe lag screw placement channel (SLSC) in the anterior column of acetabulum by the digital simulation technique (DST). Methods To find and measure the safe lag screw placement channel in the anterior column of the acetabulum under the standard 3D coordinate system and the three-dimensional coordinate system of the pelvis by establishing 96 cases of 3D finite element female die of the anterior column of acetabulum through 3D reconstruction of 48 cases of normal adult pelvic spiral CT data by Mimics 15.0. Results The parameters of SLSC of the anterior column of acetabulum:The max radius is(4.65±0.54)mm in male, and(3.71±1.68)mm in female;The depth is(114.91±6.52)mm in male, and(102.97±6.24)mm in female;The narrowest screw placement site is in the anterior wall of the

  18. Percutaneous triple anterior screw fixation of acute combined atlas-axis fractures in elderly patients:a primary report%前路经皮三钉固定治疗老年寰枢椎联合骨折

    Institute of Scientific and Technical Information of China (English)

    王向阳; 徐华梓; 池永龙; 林焱; 黄其杉; 倪文飞; 王胜; 徐晖

    2011-01-01

    目的 探讨经皮内固定技术治疗老年(特别是合并颅脑损伤)患者急性寰枢椎联合骨折的方法及其疗效.方法 2006年3月至2011年2月,共7例老年急性寰枢椎联合骨折患者.男6例,女1例;年龄64~84岁,平均72.4岁.寰椎骨折:Jefferson骨折2例,前弓骨折2例,前后弓两处骨折2例,前后弓骨折+侧块骨折1例.枢椎齿状突骨折:AndersonⅡ型骨折6例,浅Ⅲ型骨折1例.颅脑损伤5例,均合并不同程度意识朦胧、谵妄或昏迷.对所有患者均在“C”型臂X线机监视下行经皮前路枢椎齿状突和两侧寰枢关节螺钉内固定术治疗,并分析其治疗效果.结果 手术时间36~78 min,平均56 min.同时行植骨术的患者出血20~50 ml,未行植骨术者无明显出血.7例患者均获得满意治疗效果,螺钉位置正确.无神经根、脊髓、椎动脉和食管损伤等并发症发生.全组病例平均随访10.7个月,无脱钉、弯钉及断钉发生,枢椎齿状突骨折均骨性愈合,无寰枢关节不稳.结论 对于老年特别是合并颅脑损伤患者的急性寰枢椎联合骨折,经皮前路三钉固定技术是一种简单、安全和有效的方法,有利于对患者临床护理和早期功能训练,减少并发症的发生.%Objective To evaluate the clinical effect of the percutaneous fixation for atlas-axis combined fractures in the elderly patients,especially with brain injury.Methods From March 2006 to February 2011,a total of 7 cases with C1,2 combined fractures entered the study,including 5 males and 1 female with an average age of 72.4 years (range,64-84 years).Fracture combinations included two Jefferson/type Ⅱ odontoid,two anterior ring/type Ⅱ odontoid,two anterior and posterior ring/type Ⅱ odontoid,and one anterior and posterior ring+lateral mass/type Ⅲ odontoid.There were 5 patients with head injuries in varying degrees of coma.All patients underwent percutaneous placement of odontoid screw and anterior C1,2 transarticular screws

  19. ADOLESCENT IDIOPATHIC SCOLIOSIS: EVALUATION ON THE EFFECT OF SCREW DENSITY IN THE CORRECTION

    Directory of Open Access Journals (Sweden)

    Enguer Beraldo Garcia

    2016-03-01

    Full Text Available ABSTRACT Objective: The objective was to investigate implant density or the number of screws correlated with the correction of the main curve in patients undergoing surgery for adolescent idiopathic scoliosis (AIS. Methods: We evaluated 112 medical records: 33 patients with screw density of up to 50%, and 79 patients with a density of 100%; all patients underwent surgical correction by posterior approach with transpedicular fixation. Results: In the group of patients with screw density of up to 50% the residual Cobb median was 10°; in the group with 100% density, the median was 7°. Conclusion: Biostatistical analysis showed that the group with up to 50% of screw density presented correction rate of 82.1% and the group with 100% density had correction of about 86.8%. It is therefore concluded that the difference is statistically significant in favor of the fixation with 100% density (p =0.010.

  20. Posterior Transpedicular Dynamic Stabilization versus Total Disc Replacement in the Treatment of Lumbar Painful Degenerative Disc Disease: A Comparison of Clinical Results

    Directory of Open Access Journals (Sweden)

    Tunc Oktenoglu

    2013-01-01

    Full Text Available Study Design. Prospective clinical study. Objective. This study compares the clinical results of anterior lumbar total disc replacement and posterior transpedicular dynamic stabilization in the treatment of degenerative disc disease. Summary and Background Data. Over the last two decades, both techniques have emerged as alternative treatment options to fusion surgery. Methods. This study was conducted between 2004 and 2010 with a total of 50 patients (25 in each group. The mean age of the patients in total disc prosthesis group was 37,32 years. The mean age of the patients in posterior dynamic transpedicular stabilization was 43,08. Clinical (VAS and Oswestry and radiological evaluations (lumbar lordosis and segmental lordosis angles of the patients were carried out prior to the operation and 3, 12, and 24 months after the operation. We compared the average duration of surgery, blood loss during the surgery and the length of hospital stay of both groups. Results. Both techniques offered significant improvements in clinical parameters. There was no significant change in radiologic evaluations after the surgery for both techniques. Conclusion. Both dynamic systems provided spine stability. However, the posterior dynamic system had a slight advantage over anterior disc prosthesis because of its convenient application and fewer possible complications.

  1. Anterior pedicle screw insertion for low cervical spine:anatomical observation%下颈椎前路椎弓根螺钉置入相关的解剖学观察

    Institute of Scientific and Technical Information of China (English)

    王远政; 刘洋; 陈富; 陈亮; 晏铮剑; 柯珍勇; 邓忠良

    2012-01-01

    目的:观察成人下颈椎前路椎弓根螺钉(Anterior pedicle screw,APS)置入相关的径线和角度,为该术的临床应用提供相关解剖学参数.方法:成人干燥尸体下颈椎(C3~C7)标本22具,分别用手工和CT测量椎弓根最窄处的高度、宽度及内外侧皮质厚度,椎弓根中轴线全长,轴线夹角,并进行统计学分析.随机在CT室资料库中抽取100例成人活体颈椎CT图像,用Mimics 软件行三维重建,除以上参数外,还测量进钉点位置的相关数据,计算置钉参数的95%CI.结果:22具标本的相关径线及角度,其手工测量值与CT测量值间无统计学差异.成人活体下颈椎CT图像测量结果通过95%CI的计算,可以得出:C3、C4进钉点位于椎体正中矢状面受术椎弓根对侧2~3 mm,距椎体上终板平面6~7 mm,进钉角度为外倾角46°~48°,头倾角C3:-11°~-12°,C4-6°~7°.C5进钉点位于椎体正中矢状面受术椎弓根同侧旁1~2 mm,距椎体上终板平面7~8 mm,进钉角度为外倾角47°~49°,头倾角1°~2°.C6、C7进钉点位于受术椎弓根同侧,正中矢状面旁4~5 mm,距椎体上终板平面7.5~8.5 mm,进钉角度为外倾角C6:40°~42°,C7:36°~38°,头倾角C6:6°~7°,C7:11°~13°.置钉长度选择30、32、34 mm较为适宜,螺钉直径可选择3.5 mm或4.0mm.结论:本实验证实了CT测量下颈椎APS置入技术相关参数的准确性,同时在国内首次利用大样本研究对该技术置钉参数进行了探索.%Objective:To observe the pathlines and angles related to lower cervical spine anterior pedicle screw(APS)fixation in adults so as to provide anatomical parameters in clinics. Methods:A total of 22 cervical spine(C3-C7)specimens of human adult cadavers were individually measured by hand and CT scan to determine the height and width of the narrowest part in pedicle, thickness of inner and outer cortexes, pedicle axis length and included angle of axes followed by statistical methods. One

  2. Biomechanical evaluation on the stability of anterior cervical pedicle screw fixation for osteoporosis%生物力学评价颈椎前路椎弓根螺钉植入骨质疏松椎骨内的稳定性

    Institute of Scientific and Technical Information of China (English)

    李振伟; 向阳明

    2015-01-01

    segments, the stability of fixator and bone graft is poor due to big bone graft span, which may easily cause fusion failure and pseudarthrosis, and impact curative effects. OBJECTIVE:To investigate biomechanical stability of anterior cervical pedicle screw implantation for osteoporosis in the vertebra. METHODS:A total of 12 human cervical vertebrae were col ected, including 6 vertebrae with normal bone density and 6 vertebrae with osteoporosis. Data of 60 vertebra specimens were analyzed. 30 osteoporotic specimens implanted in anterior cervical pedicle screw were set as anterior cervical pedicle screw group. 30 normal specimens implanted in anterior cervical pedicle screw were set as anterior vertebral screw group. According to bone density, 40 vertebrae were col ected in above two groups, and were considered as normal bone mineral density group, instant osteoporosis group, fatigue normal bone mineral density group, and fatigue osteoporosis group (n=10). Bone mineral density of each vertebra was detected using dual-energy X-ray absorptiometry. Biomechanical index of two kinds of screws was detected using ElectroForce 3510 material testing machine. RESULTS AND CONCLUSION:Bone mineral content, vertebral screw pul-out strength, vertebral screw pul-out stiffness, pedicle screw pul-out strength, and pedicle screw pul-out stiffness were significantly higher in the anterior cervical pedicle screw group than in the anterior vertebral screw group (P<0.05). The maximum axial pul-out strength of normal bone mineral density group, instant osteoporosis group, fatigue normal bone mineral density group, and fatigue osteoporosis group was significantly higher than in the anterior vertebral screw group (P<0.05). The results confirmed that osteoporotic vertebral biomechanical performance is more stable in anterior pedicle screws compared with the anterior vertebral screw.

  3. [Intra-articular reinforcement of a partially torn anterior cruciate ligament (ACL) using newly developed UHMWPE biomaterial in combination with Hexalon ACL/PCL screws: ex-vivo mechanical testing of an animal knee model].

    Science.gov (United States)

    Fedorová, P; Srnec, R; Pěnčík, J; Dvořák, M; Krbec, M; Nečas, A

    2015-01-01

    PURPOSE OF THE STUDY Recent trends in the experimental surgical management of a partial anterior cruciate ligament (ACL) rupture in animals show repair of an ACL lesion using novel biomaterials both for biomechanical reinforcement of a partially unstable knee and as suitable scaffolds for bone marrow stem cell therapy in a partial ACL tear. The study deals with mechanical testing of the newly developed ultra-high-molecular-weight polyethylene (UHMWPE) biomaterial anchored to bone with Hexalon biodegradable ACL/PCL screws, as a new possibility of intra-articular reinforcement of a partial ACL tear. MATERIAL AND METHODS Two groups of ex vivo pig knee models were prepared and tested as follows: the model of an ACL tear stabilised with UHMWPE biomaterial using a Hexalon ACL/PCL screw (group 1; n = 10) and the model of an ACL tear stabilised with the traditional, and in veterinary medicine used, extracapsular technique involving a monofilament nylon fibre, a clamp and a Securos bone anchor (group 2; n = 11). The models were loaded at a standing angle of 100° and the maximum load (N) and shift (mm) values were recorded. RESULTS In group 1 the average maximal peak force was 167.6 ± 21.7 N and the shift was on average 19.0 ± 4.0 mm. In all 10 specimens, the maximum load made the UHMWPE implant break close to its fixation to the femur but the construct/fixation never failed at the site where the material was anchored to the bone. In group 2, the average maximal peak force was 207.3 ± 49.2 N and the shift was on average 24.1 ± 9.5 mm. The Securos stabilisation failed by pullout of the anchor from the femoral bone in nine out of 11 cases; the monofilament fibre ruptured in two cases. CONCLUSIONS It can be concluded that a UHMWPE substitute used in ex-vivo pig knee models has mechanical properties comparable with clinically used extracapsular Securos stabilisation and, because of its potential to carry stem cells and bioactive substances, it can meet the requirements for

  4. 前路减压植骨可吸收螺钉内固定治疗颈椎病%The anterior decompression and bone grafting with bio-absorbable screw fixation for cervical spondylosis

    Institute of Scientific and Technical Information of China (English)

    王栋; 贺西京; 李浩鹏; 张健; 徐思越; 杨平林; 王国毓

    2009-01-01

    Objective:To observe the early clinical effect of the cervical spendylosis treated by the fixation with bio-absorbable screw after cervical anterior decompression and bone grafting.Method:26 cases suffered from cervical spondylosis who were treated by anterior compression,bone grafting and fixating with 2 bio-ab-serbable screws from Mar. 2007 to Sep. 2008,including 16 males and 10 females with an average age of 49.4 years (38-70 years ).There were 11 cases with cervical spondylotic myelopathy,5 with cervical spendylofic radieulopathy and 10 with mixed type of cervical spondylosis.Clinical data of these patients was analyzed ret-rospectively.One intervertebral space involvement was in 8 cases,and two spaces involvement in 18 cases.All patients underwent anterior decompression and bone grafting,in which the grafted bone was fixated by 2 bio-absorptive screws (PLLA,diameter:2.7mm) from the midline of graft bone to the bone surface of upper and lower vertebrae in 45°.Cervical collar was commonly used for 4-6 weeks after operation.All cases were fol-lowed-up every month in outpatient department to observe the improvement of symptoms and evaluate the fu-sion of bone graft.Neurological function recovery was observed by JOA score.Result:Operations of all cases were finished and screws were placed successfully.The operative incisions healed well.The excellent and good rate of symptom improvement was 84.2%,the graft fusion time was 3.3±0.6 months (range,3.2-4.6 months).No obvious complications were found.Conclusion:The cervical spendylosis with one or two-level involvement can be effectively treated by anterior decompression and bone grafting with bio-absorbable screw fixation.This operative method is safe and can avoid the complications induced by metal implants.%目的:观察颈椎前路减压植骨可吸收螺钉内同定治疗颈椎病的初步临床疗效.方法:2007年3月~2008年9月我院应用颈椎前路减压植骨可吸收螺钉

  5. Embolization by Direct Puncture with a Transpedicular Approach Using an Isocenter Puncture (ISOP) Method in a Patient with a Type II Endoleak After Endovascular Aortic Repair (EVAR)

    Energy Technology Data Exchange (ETDEWEB)

    Ogawa, Yukihisa, E-mail: yukky.oct.22@gmail.com; Hamaguchi, Shingo [St. Marianna University, School of Medicine, Department of Radiology (Japan); Nishimaki, Hiroshi [St. Marianna University, School of Medicine, Department of Cardiovascular Surgery (Japan); Kon, Yuri [St. Marianna University, School of Medicine, Department of Radiology (Japan); Chiba, Kiyoshi; Sakurai, Yuka [St. Marianna University, School of Medicine, Department of Cardiovascular Surgery (Japan); Murakami, Kenji; Arai, Yasunori [St. Marianna University, School of Medicine, Department of Radiology (Japan); Miyairi, Takeshi [St. Marianna University, School of Medicine, Department of Cardiovascular Surgery (Japan); Nakajima, Yasuo [St. Marianna University, School of Medicine, Department of Radiology (Japan)

    2015-06-15

    BackgroundEndovascular aortic repair (EVAR) requires further intervention in 20-30 % of cases, often due to type II endoleak (T2EL). Management options for T2EL include transarterial embolization, direct puncture (DP), or transcaval embolization. We report the case of an 80-year-old man with T2EL who successfully underwent DP embolization.MethodsEmbolization by DP was performed with a transpedicular approach using an isocenter puncture (ISOP) method. An isocenter marker (ICM) was placed at a site corresponding to the aneurysm sac on fluoroscopy in two directions (frontal and lateral views). A vertebroplasty needle was inserted tangentially to the ICM under fluoroscopy and advanced to the anterior wall of the vertebral body. A 20 cm-length, 20-G-PTCD needle was inserted through the outer needle of the 13-G needle and advanced to the ICM. Sac embolization using 25 % N-buty-2-cyanoacrylate diluted with Lipiodol was performed. After complete embolization, rotational DA confirmed good filling of the sac with Lipiodol. The outer cannula and 13-G needle were removed and the procedure was completed.ResultsThe patient was discharged the next day. Contrast-enhanced computed tomography 1 and 8 months later showed no Lipiodol washout in the aneurysm sac, no endoleak recurrence, and no expansion of the excluded aneurysm.ConclusionDP with a transpedicular approach using ISOP may be useful when translumbar and transabdominal approaches prove difficult.

  6. Percutaneous coaxial transpedicular biopsy of vertebral body lesions during vertebroplasty

    Energy Technology Data Exchange (ETDEWEB)

    Minart, D.; Vallee, J.N.; Cormier, E.; Chiras, J. [Service de Neuroradiologie Diagnostique et Interventionnelle Charcot, Groupe Hospitalo-Universitaire Pitie-Salpetriere, Paris (France)

    2001-05-01

    We evaluated the safety and histological results of percutaneous transpedicular biopsy in patients undergoing vertebroplasty for vertebral collapse. Over a 6 year period, we carried out biopsies in 46 patients who underwent percutaneous injection of acrylic surgical cement for 57 collapsed vertebrae, because the diagnosis was not clearly established on clinical or imaging grounds. All procedures were performed under fluoroscopic guidance via a coaxial bitranspedicular approach used for vertebroplasty. We performed a clinical examination and CT after every procedure and approximately 6 months thereafter. Biopsies contributed to in 55 (96.5 %) of the 57 vertebral lesions. Biopsy material was inadequate in one case (1.7 %) and one biopsy was a false-negative (1.7 %). The accuracy of the histological results was 98.2 %, allowing a correct diagnosis in 55 of the 56 procedures. Of the 37 lesions in 28 patients with a history of a tumour, the final diagnosis was osteoporotic collapse in 25 (67.6 %), metastasis in nine (24.3 %), and myeloma in three (8.1 %). The final diagnosis in the 19 lesions in 17 patients without a known tumour was osteoporotic collapse in 12 (63.2 %), metastasis in five (26.3 %), and amyloidosis in two (10.5 %), the latter in one patient. No complications were observed. (orig.)

  7. 颈前路螺钉矢状角对相邻节段影响的生物力学研究%A biomechanical study of effects of anterior cervical screw sagittal angle on adjacent segments

    Institute of Scientific and Technical Information of China (English)

    陆兆华; 赵峰; 苏维成; 赵晓勇; 赵彦涛; 李忠海

    2015-01-01

    目的:采用三维有限元方法分析颈前路螺钉矢状角( sagittal screw angle,SSA )对相邻节段生物力学的影响,判断 SSA 是否是引起邻近节段病的危险因素。方法基于健康成年男性 C3~7节段 CT 图像建立颈椎有限元模型。模拟颈前路 C5椎体次全切除、C4~6钢板内固定术,按照 SSA (0°,0°)(5°,5°)(10°,10°)分别建模,计算在不同的 SSA 下,C4上终板、C6下终板以及钢板的应力变化情况。结果 C4上终板在前屈时前方区域所受应力最大,随着 SSA 的增加,C4上终板整体所受的最大应力逐渐减小,SSA 增大10°后,C4上终板前方区域的最大应力减小12.67%。C6下终板在前屈时前方区域所受应力最大,随着 SSA 的增加,C6下终板整体所受的最大应力逐渐减小,SSA 增大10°后,C6下终板前方区域的最大应力减小7.99%。钢板在前屈和后伸时其最大应力均较集中于中部区域,并且显著高于上部及下部区域,随着 SSA 的增加,钢板受到的应力会逐渐增加。结论在颈椎前路融合内固定手术中,增大 SSA,可增加钢板承受的应力,同时降低邻近节段终板的应力,从而减少邻近节段病的发生。%Objective To analyze effects of different screw sagittal angles ( SSA ) on the stress of adjacent levels, and determine whether SSA is a risk factor of adjacent segment disease ( ASD ).Methods A three-dimensional ifnite element ( FE ) model of intact C3-7 segments was developed and validated based on healthy males. C5 anterior corpectomy and allograft interbody fusion with a rigid anterior screw-plate construction was created from C4 to C6. Three additional FE models were developed from the fusion model corresponding to 3 different combinations of SSA: ( 0°, 0° ), ( 5°, 5° ), and ( 10°, 10° ). Von Mises stress on the C4 superior end-plate, C6 inferior end-plate and screw-plate were analyzed.Results The largest stress

  8. MINIMALLY INVASIVE ANTERIOR TRANSARTICULAR SCREW FIXATION AND FUSION FOR ATLANTOAXIAL INSTABILITY%微创前路经寰枢椎关节突固定融合治疗寰枢椎不稳

    Institute of Scientific and Technical Information of China (English)

    陆焱; 王建; 郑文杰; 刘杰; 黄博

    2012-01-01

    Objective To investigate the clinical results and compl ications of minimally invasive anterior transarticular screw fixation and fusion for atlantoaxial instability. Methods Between May 2007 and December 2010, 13 patients with atlantoaxial instability were treated with minimally invasive anterior transarticular screw fixation and fusion under endoscope. There were 11 males and 2 females, aged 17-61 years (mean, 41.3 years). The time between injury and operation was 5-14 days (mean, 7.4 days). All cases included 6 patients with Jefferson fracture, 5 with odontoid fracture, and 2 with os odontoideum. According to Frankel classification of nerve functions, 2 cases were rated as grade D and 11 cases as graed E. The operation time, intra-operative blood loss, radiation exposure time, and complications were recorded and analyzed. The stability was observed by X-ray films. The clinical outcome was assessed using the Frankel scale, and the fusion rates were determined by CT scan three-dimensional reconstruction at last follow-up. Results The mean operation time was 124 minutes (range, 95-156 minutes); the mean intra-operative blood loss was 65 mL (range, 30-105 mL); and the mean radiation exposure time was 41 seconds (range, 30-64 seconds). Thirteen patients were followed up 12-47 months (mean, 25.9 months). No blood vessel and nerve injuries or internal fixator failure occurred. The bone fusion time was 6 months, and the dynamic cervical radiography showed no instability occured. At last follow-up, the neurological function was grade Ein all patients. The fusion rate was 84.6% (11/13). No continuous bone bridge was seen in the joint space of 2 patients, but they achieved stability. Conclusion Minimally invasive anterior transarticular screw fixation and fusion is a safe and effective procedure for treatment of atlantoaxial instability.%目的 探讨微创前路经寰枢椎关节突固定融合治疗寰枢椎不稳的临床效果和并发症.方法 2007年5月-2010年12

  9. Multiaxial inter-vertebral and vertebral pedicle pedicle screw fixation for spinal fractures: a biomechanical comparative study%经伤椎与跨伤椎万向钉置钉固定脊柱骨折的生物力学对比研究

    Institute of Scientific and Technical Information of China (English)

    王洪伟; 周跃; 李长青; 刘涛; 赵卫东

    2010-01-01

    Objective To compare the biomechanical stability of the multiaxial inter-vertebral and vertebral pedicle screw fixation in vertebral fracture fixation of the spinal fracture model. Methods Six lumbar fracture models were made on fresh calf lumbar spine specimens at L1 -L5 to compare the stability of four transpedicular multiaxial screws and six transpedicular multiaxial screws by examining the range of motion (ROM) in flexion, extension, lateral bending and torsion. Results Biomechanical experiment found that four multiaxial screws transpedicular fixation specimen exhibited a significantly larger ROM in flexion and extension than the intact specimens; while six multiaxial transpedicular screw fixation specimen exhibited a smaller ROM than the intact specimens (t =4. 844,P <0. 01 ;t =3. 722,P <0.05 ). The ROM of six multiaxial transpedicular screw fixation specimen was significantly smaller than that of four multiaxial transpedicular screw fixation specimen in flexion, extension, lateral bending and rotation ( P < 0. 01 ). Conclusions Compared with four multiaxial transpedicular screw fixation, six multiaxial transpedicular screw fixation exhibits a significantly larger stability in flexion, extension, lateral bending and rotation, as provides theoretical basis for treatment of thoracolumbar fractures with pedicular screw fixation.%目的 对比评估经伤椎6钉与跨伤椎4钉固定脊柱骨折的生物力学稳定性.方法 6具新鲜冰冻小牛腰椎标本L1~L5节段,制备成腰椎前中柱损伤模型.比较4钉固定组与6钉固定组的三维6个方向的运动范围.结果 生物力学试验证实,4钉固定组在屈曲、后伸运动方向上的稳定性都较对照组小,但差异无统计学意义.6钉固定组在屈曲、后伸运动方向上的稳定性均较完整对照组大,且差异有统计学意义(t=4.844,P<0.01;t=3.722,P<0.05).6钉固定组在各个方向的运动范围均小于4钉固定组,且两组在屈曲、后伸、侧屈

  10. C形臂X线透视导航下微创经皮拉力螺钉治疗髋臼前柱骨折%Treatment of anterior acetabular column fracture with minimally invasive percutaneous lag screws by C-arm X-ray fluoroscopy-based navigation

    Institute of Scientific and Technical Information of China (English)

    司庆华; 唐佩福; 丁珮; 胡磊; 樊喻波; 张立海; 彭晔; 袁新成; 董天祥; 娄昕

    2013-01-01

      目的探讨C型臂X线机透视导航下使用微创经皮拉力螺钉内固定治疗髋臼前柱骨折的方法及疗效.方法对2009年3月-2011年9月,在我院创伤骨科住院的8例无移位或轻度移位的髋臼前柱骨折患者,应用C形臂X线透视导航,用微创经皮拉力螺钉治疗髋臼前柱骨折.按Nakatani分型:Ⅰ型4例,Ⅱ型3例,Ⅲ型1例.受伤致手术时间为2~7 d.结果8例患者,男5例,女3例,年龄19~69岁,共置入10枚髋臼前柱经皮螺钉,其中2例为双侧髋臼前柱骨折,其余6例为单侧髋臼前柱骨折,各置入1枚螺钉.术后8例全部获得随访,随访时间10~26个月.8例全部骨性愈合,1例遗留轻度移位,无血管神经损伤等并发症.结论 C型臂X线机透视导航下使用微创经皮拉力螺钉内固定治疗髋臼前柱骨折可提高螺钉的精确度,有利于功能康复.%Objective To study the treatment of anterior acetabular column fractures with minimally invasive percutaneous lag screws by C-arm X-ray fluoroscopy-based navigation. Methods Eight patients with no or mild shift of anterior acetabular column fractures were treated with minimally invasive percutaneous lag screw by C-arm X-ray fluoroscopy- based navigation in our department from March 2009 to September 2011. The fractures were classified as typeⅠin 4 patients, typeⅡin 3 patients, and typeⅢin 1 patient according to Nakatani classification. The time from fracture to operation was 2~7 days. Results Of the 8 patients with 10 screws inserted, 5 were males and 3 were females aged 19~69 years, 2 were diagnosed with bilateral anterior acetabular column fracture and 6 with unilateral anterior acetabular column fracture with 1 screw inserted, respectively. The patients were followed up for 10~26 months, during which their fractures were healed with no complications such as vascular and nerve injury except for mild shift in 1 patient. Conclusion Internal fixation of anterior acetabular column fractures with

  11. "NIMS technique" for minimally invasive spinal fixation using non-fenestrated pedicle screws: A technical note

    Directory of Open Access Journals (Sweden)

    Alugolu Rajesh

    2015-01-01

    Full Text Available Study Design: Case series. Objective: To reduce the cost of minimally invasive spinal fixation. Background: Minimally invasive spine (MIS surgery is an upcoming modality of managing a multitude of spinal pathologies. However, in a resource-limited situations, using fenestrated screws (FSs may prove very costly for patients with poor affordability. We here in describe the Nizam′s Institute of Medical Sciences (NIMS experience of using routine non-FSs (NFSs for transpedicular fixation by the minimally invasive way to bridge the economic gap. Materials and Methods: A total of 7 patients underwent NFS-minimally invasive spine (MIS surgery. Male to female distribution was 6:1. The average blood loss was 50 ml and the mean operating time was 2 and 1/2 h. All patients were mobilized the very next day after confirming the position of implants on X-ray/computed tomography. Results: All 7 patients are doing well in follow-up with no complaints of a backache or fresh neurological deficits. There was no case with pedicle breach or screw pullout. The average cost of a single level fixation by FS and NFS was `1, 30,000/patient and `32,000/patient respectively ($2166 and $530, respectively. At the end of 1-year follow-up, we had two cases of screw cap loosening and with a displacement of the rod cranio-caudally in one case which was revised through the same incisions. Conclusions: Transpedicular fixation by using NFS for thoracolumbar spinal pathologies is a cost-effective extension of MIS surgery. This may extend the benefits to a lower socioeconomic group who cannot afford the cost of fenestrated screw (FS.

  12. Anatomic security of applying different numbers of screws at the sacrum sides in the anterior double plate fixation of the sacroiliac joint%骶髂关节前路双钢板固定骶骨侧不同螺钉数量的解剖安全性研究

    Institute of Scientific and Technical Information of China (English)

    刘佳; 高仕长; 倪卫东; 蒋电明; 周程鹏

    2012-01-01

    0bjective: To compare the anatomic security of applying different numbers of screws at the sacrum sides in the anterior double plates fixation of the sacruiliac joint and to clarify which is safer when the stability of the fixation is considered. Methods: (1) Totally 15 normal cadavers pelvis were scanned by CT. Thin-section CT scan data were saved and analyzed by the software Materi-alise's interactive medical image control system (MIMICS 10.0). The virtual operations of the anterior double plates approach for fixation of the sacroiliac joint were performed in the same software. (2)The left sides of the sacroiliac joint were named as group A,in which two screws were placed into the sacrum sides. The right sides of the sacroiliac joint were named as group B,in which one screw was placed into the sacrum sides. The distances from the medial edge of the plates to the lateral sides of the anterior branches of lumbar nerves 4,5 were measured. The relationship of the screws and the sacroiliac joint was checked by radiograph. Results: (1 )In the virtual operations,the sacrum sides can accommodate two screws safely- (2)In group A,the distances from the medial edge of the upper and lower plates to the lateral sides of the anterior branches of lumbar nerve 5 were (3.0 ± 1.4) mm and (1.5 ± 1.0) mm respectively. The upper and lower plates can be placed below the anterior branches of lumbar nerve 4 safely. In group B,the distances from the medial edge of the upper plates to the lateral sides of the anterior branches of lumbar nerves 4,5 were (5.0 ± 1.1) mm and (10.3 ±1.3) mm respectively and those from the medial edge of the lower plates were (2.7 ± 0.5) mm and (5.1 ±0.9) nun respectively. (3)ln X-ray examination,no screw of the left upper plates was found in the sacroiliac joint in group A and 4 screws of the left lower plates were observed. On the other hand, no screw of the right plates (lower and upper) in the group B was found in the sacroiliac joint. Conclusions

  13. Anterior cervical plating plus axial screw fixation for treating cervical flexion-distraction injury: anatomic study%颈椎前路钢板并轴向螺钉固定治疗屈曲牵张型损伤的解剖学研究

    Institute of Scientific and Technical Information of China (English)

    瞿东滨; 邹琳; 杨勇; 徐准; 程勇泉

    2012-01-01

    Objective To study the anatomical flexibility of anterior cervical plating plus axial screw fixation for treating cervical flexion-distraction. Methods Fifty cases of digital lateral X-ray films from adult healthy volunteers aged 24-48 years, with mean 28 years, were measured directly in the JW-PACS picture system. Measuring parameters included vertebral body height, intervertebral disc height and disc depth. The line started from anteroinferior point of the inferior vertebrae to posterosuperior point of the superior vertebrae was drawn to mimic the axial screw fixation in the lateral film. The maximal screw length, screw cephalic inclination angle and the distance between screw and anterior vertebral margin at disc level was recorded. Simulated anterior cervical plating and axial screw fixation was carried out in one preserved human specimen under the guidance of C-arm X-ray fluoroscope. Results The maximal length of anterior cervical axial screw was (41.18+3.92 )mm, and the axial screw inclination angle (25.21±3.58)°. The suitable depth of interbody graft was more than (11.69±1.63)mm, but less than (17.09±1.50)mm of disc depth. Simulated procedure in the preserved specimen demonstrated that axial screw fixation could be successfully completed at C2/3, C3/4, C4/5, and C5/6 levels, but difficult be performed at C6/7 due to obstacle of sternum. Conclusions The flexibility of axial screw fixation plus anterior cervical plating is confirmed from this study for managing of cervical flexion-distraction injuries.%目的 提出一种联合颈椎前路钢板固定治疗屈曲牵张型颈椎损伤的新术式—颈椎轴向螺钉固定术,进行解剖学可行性研究.方法 随机调取50例正常成年志愿者的颈椎侧位片.年龄22~48岁,平均28岁.通过JW-PACS图像系统,测量C2~6椎体高度;C2/3~C5/6椎间盘高度以及椎间盘矢径;并模拟轴向螺钉固定,即下位椎体前下缘至上位椎体后上缘的连线,测量轴向螺钉最大

  14. OPTIMAL DISTAL SCREW ALIGNMENT IN THE GAMMA NAIL

    Institute of Scientific and Technical Information of China (English)

    Ching-KongChao; Chun-ChingHsiao; Po-QuangChen

    2002-01-01

    The effect of stress distribution due to the changes of the distal screw alignment in relation to the Gamma nail and the femoral shaft is thoroughly studied in this paper. Failure of the Gamma nail composite occurs through the cranial aperture of the distal screws and the insertion hole for the lag screw due to nonunion, delayed-union and continued weight-bearing. A three-dimensional finite element model was used to study the fractured femur, the Gamma nail, the lag screw and the distal locking screws. The first and the second distal screws were inserted into the Gamma nail in four different configurations. We found that the stress of the Gamma nail composite was substantially reduced with the two screws configured in the anterior to posterior direction. This alignment can bear greater loading in the more demanding fracture types. In the subtrochanteric fracture or the comminuted fractures at the proximal femur, the optimal alignment of the two distal screws was in the anterior to posterior direction.

  15. 下颈椎前路内固定联合后路经关节金属螺钉置入固定的生物力学稳定性%Biomechanical stability of the lower cervical spine inter-fixation by anterior approach combined with posterior articular screws

    Institute of Scientific and Technical Information of China (English)

    康建平; 冯大雄; 王清; 钟德君; 李骏; 叶飞; 王松

    2011-01-01

    BACKGROUND: A simple anterior corpectomy or discectomy, or simple posterior open canal to expand a single trip cannot fully complete three-column spinal cord decompression and spinal stabilization in patients with degenerative cervical stenosis.OBJECTIVE: To study the biomechanical stability of the lower cervical spine inter-fixation by anterior approach combined with posterior srticular screws.METHODS: Ten cervical spine specimens were gained from cadavers. Every specimen was managed via two methods sequentially: The first method was by posterior C3-C7 open-door laminoplasty combined with posterior articular screw fixation andby anterior C5 subtotal corpectomy with bone granule graft in the titanium mesh and ORION fixation (test group); The second method was by posterior C3-C7 open-door laminoplasty and by anterior C5 subtotal corpectomy with bone granule graft in thetitanium mesh and ORION fixation (control group).RESULTS AND CONCLUSION: Compared with the control group, displacement angles of flexion, extension, left/right lateroflexion left/right rotation in the test group were lower (P < 0.001). The findings indicated that: ①The lower spine gained the excellent biomechanical stability in flexion, extension, lateroflexion and rotation via the treatment of anterior fixation combined posterior articular screw fixation. ②The treatment of anterior fixation combined with posterior articular screw fixation provided significant biomechanical stability to the lower cervi cal spine in flexion position.%背景:对退变性颈椎管狭窄单纯采用前路椎体次全切除或椎间盘切除或单纯后路单开门椎管扩大成行均不能彻底完成脊髓减压和脊柱三柱稳定.目的:探讨下颈椎前路固定联合后路经关节螺钉固定的生物力学稳定性.方法:正常成人尸体颈椎标本,每具分别制作以下两种模型:①经后路C3~C7单开门和下颈椎前路C5椎体次全切除钛网支撑植骨、ORION内固定

  16. Evaluacion de la biopsia transpedicular guiada por TAC Avaliação da biópsia transpedicular guiada por TC Evaluation of transpedicular percutaneous biopsy guided by CT

    Directory of Open Access Journals (Sweden)

    Luis Miguel Rosales Olivarez

    2012-09-01

    Full Text Available OBJETIVO: Valorar la utilidad de la biopsia transpedicular percutánea guiada por Tomografía Axial Computarizada en conjunto con la sistematización de estudios como pruebas diagnósticas de la etiología de la destrucción vertebral. MÉTODOS: Estudio de serie de casos prospectivo transversal de 21 pacientes a los que se les realizó biopsia transpedicular percutánea guiada por Tomografía Axial Computarizada y estudios de laboratorio y gabinete de marzo a julio del 2011, para evaluar su utilidad en el diagnóstico de destrucción vertebral. RESULTADOS: Fueron 21 pacientes, 14 hombres y 7 mujeres, con edad media de 59,2 años, cuyos niveles más afectados estuvieron en L1, L2 y L3. El reporte de la biopsia tuvo una precisión diagnóstica del 90,4%. En 2 casos se realizó correlación clínica entre biopsia y sistematización de estudios para obtener el diagnóstico. CONCLUSIÓN: La biopsia guiada por Tomografía Axial Computarizada es una técnica sencilla, útil, de bajo costo y eficaz en el estudio de la destrucción vertebral; la sistematización de estudios permite corroborar el diagnóstico de la biopsia.OBJETIVO: Avaliar a utilidade da biópsia transpedicular percutânea guiada por tomografia axial computadorizada em conjunto com a sistematização de estudos, como exames diagnósticos da etiologia da destruição vertebral. MÉTODOS: Estudo de série de casos, prospectivo e transversal de 21 pacientes submetidos à biópsia transpedicular percutânea guiada por tomografia axial computadorizada e exames laboratoriais e radiológicos, de março a julho de 2011, para avaliar sua utilidade no diagnóstico de destruição vertebral. RESULTADOS: Foram analisados 21 pacientes, 14 homens e 7 mulheres, com média de idade de 59,2 anos, cujos níveis mais afetados foram L1, L2 e L3. O laudo da biópsia teve precisão diagnóstica de 90,4%. Em dois casos, realizou-se a correlação clínica entre biópsia e sistematização de exames para obter

  17. 前路经寰枢关节螺钉内固定术置钉安全性的实验验证研究%An experimental study on the safety of screwp lacement in anterior atlantoaxial transarticular screw fixation

    Institute of Scientific and Technical Information of China (English)

    郑宇; 蔡贤华; 党建军; 金鸿宾; 黄卫兵; 曾晓华; 杨昱恒

    2014-01-01

    Objective To investigate the relative safety range of screw placement in anterior atlantoaxial transarticular screw ifxation and to provide more anatomical data for Chinese surgeons. Methods The key point of anterior atlantoaxial transarticular screw ifxation was 4 mm over the junction of the inferior edge of the atlantoaxial anterior arch and its lateral edge. A surgery model was established in cervical specimens from 6 embalmed human bodies, and the operation of screw placement was repeated. The safety range measured by multislice computed tomography ( MSCT ) 3 D reconstruction was further clarified, so as to be used as a guide in clinical application. Results No screws perforating the superior articular surface of the atlas were found. It was ( 2.80±0.12 ) mm from the screw tip to the superior articular surface of the atlas. Among the 3 multi-planar reconstruction ( MPR ) transverse sections of the superior edge of the transverse foramen of the atlas and the superior edge and inferior edge of the atlantoaxial joint surface, the closest distance was ( 6.51±0.32 ) mm from the screw of the superior edge of the atlantoaxial joint surface ( transverse section B ) to the spinal canal. The closest distance was ( 5.52±1.22 ) mm from the screw of the superior edge of the atlantoaxial joint surface ( transverse section C ) to the vertebral artery, and the distance was ( 2.80±0.12 ) mm from the screw to the superior articular surface of the massa lateralis atlantis. No injuries in the spinal cord, vertebral artery or atlantooccipital joint were found. Conclusions It is feasible and safe in clinical practice to set the screw according to Lu’s standard and to take the relevant anatomical data obtained by AW 3 D software of GE RA600 PACS workstation as the experimental basis, which has been successfully veriifed.%目的:验证前路经寰枢关节螺钉内固定术螺钉置入的相对安全范围,为此手术提供解剖学依据。方法前路经寰枢关节螺

  18. 前路钛板加方形区螺钉治疗髋臼双柱骨折的坐位生物力学分析%Biomechanical analysis of sitting position in both-column acetabular fractures fixed by anterior plate-screws in quadrilateral area

    Institute of Scientific and Technical Information of China (English)

    吴咏德; 蔡贤华; 刘曦明; 张红喜

    2013-01-01

    目的 探讨前路钛板加方形区螺钉治疗髋臼双柱骨折早期取坐位的可能性.方法 取成年防腐保湿处理的全骨盆标本6具,保留韧带及髋关节囊,制作单侧髋臼高位双柱骨折模型,随机先后采用前路钛板加方形区螺钉(B组)或常规钛板加1/3管型钛板(C组)内固定,固定标本于ZWICKZ100电子万能材料试验机上,模拟坐立位以400~700N加载,采用循环多次测量的方法,每组含标本6具,先后测定完整骨盆(A组)、B组及C组后柱内壁横向位移、骨盆轴向位移,计算骨盆轴向刚度.结果 随着载荷增加,位移:A组0.05),骨盆轴向位移及刚度有统计学差异(P0.05) ,while the difference of the axial displacement and the stiffness in pelvis were markedly significant (P <0.01).Conclusion The both-eolumn acetabular fractures fixed by anterior titanium plate-screws in quadrilateral area or the conventional 1/3 tube type titanium plate has the ideal internal result which allows patients to take the seat early ,but "anterior titanium plate-screws in quadrilateral area" is better than the conventional 1/3 tube type titanium plate on the stability of the hip joint ,which is close to the stability of normal pelvis.Sitting early is more secure and reliable in anterior titanium plate -screws in quadrilateral area.

  19. Odontoid screw fixation for fresh and remote fractures

    Directory of Open Access Journals (Sweden)

    Rao Ganesh

    2005-01-01

    Full Text Available Fractures of the odontoid process are common, accounting for 10% to 20% of all cervical spine fractures. Odontoid process fractures are classified into three types depending on the location of the fracture line. Various treatment options are available for each of these fracture types and include application of a cervical orthosis, direct anterior screw fixation, and posterior cervical fusion. If a patient requires surgical treatment of an odontoid process fracture, the timing of treatment may affect fusion rates, particularly if direct anterior odontoid screw fixation is selected as the treatment method. For example, type II odontoid fractures treated within the first 6 months of injury with direct anterior odontoid screw fixation have an 88% fusion rate, whereas fractures treated after 18 months have only a 25% fusion rate. In this review, we discuss the etiology, biomechanics, diagnosis, and treatment (including factors affecting fusion such as timing and fracture orientation options available for odontoid process fractures.

  20. Percutaneous Anterior Column Fixation for Acetabulum Fractures, Does It Have to Be Difficult?-The New Axial Pedicle View of the Anterior Column for Percutaneous Fixation.

    Science.gov (United States)

    Zhang, Lihai; Zhang, Wei; Mullis, Brian; Liu, Daohong; Xiong, Qi; Lv, Houchen; Ji, Xinran; Peng, Ye; Tang, Peifu

    2016-01-01

    Anterior column percutaneous screw fixation can be challenging. The purpose of this new technique is to offer a rapid, simple, and safe method to place an anterior screw. The authors used a 3-dimensional reconstruction simulation, cadaver study, and a clinical case series to demonstrate this new alternative to standard previously described techniques.

  1. Posterior cervical spine arthrodesis with laminar screws: a report of two cases

    Directory of Open Access Journals (Sweden)

    Sugimoto,Yoshihisa

    2007-04-01

    Full Text Available We performed fixation using laminar screws in 2 patients in whom lateral mass screws, pedicle screws or transarticular screws could not be inserted. One was a 56-year-old woman who had anterior atlantoaxial subluxation (AAS. When a guide wire was inserted using an imaging guide, the hole bled massively. We thought the re-insertion of a guide wire or screw would thus increase the risk of vascular injury, so we used laminar screws. The other case was an 18-year-old man who had a hangman fracture. Preoperative magnetic resonance angiography showed occlusion of the left vertebral artery. A laminar screw was inserted into the patent side (i.e., the right side of C2. Cervical pedicle screws are the most biomechanically stable screws. However, their use carries a high risk of neurovascular complications during screw insertion, because the cervical pedicle is small and is adjacent laterally to the vertebral artery, medially to the spinal cord, and vertically to the nerve roots. Lateral mass screws are also reported to involve a risk of neurovascular injuries. The laminar screw method was thus thought to be useful, since arterial injuries could thus be avoided and it could also be used as a salvage modality for the previous misinsertion.

  2. 内窥镜辅助下前路经寰枢关节螺钉固定植骨融合术治疗上颈椎不稳%Endoscopy-assisted anterior transarticular screw fixation and bone grafting for upper cervical instability

    Institute of Scientific and Technical Information of China (English)

    姚女兆; 王文军; 王麓山; 晏怡果; 李学林; 欧阳智华

    2012-01-01

    目的:探讨内窥镜辅助下前路经寰枢关节螺钉固定植骨融合术治疗上颈椎不稳的临床可行性及其疗效.方法:2006年1月至2009年12月采用内窥镜辅助下前路经寰枢关节螺钉固定植骨融合术治疗上颈椎不稳患者13例,男8例,女5例;年龄17~65岁,平均46.8岁.JeffersonⅡ型骨折6例,JeffersonⅢ型骨折1例,寰枢椎脱位3例,陈旧性齿状突骨折3例.患者均有枕颈部不适和活动受限,术前VAS评分为3.2~4.1分,平均3.8分;2例伴有不同程度脊髓功能损害者,按Frankel分级C级1例,D级1例.随访患者临床症状改善和植骨融合情况.结果:均在内镜辅助下顺利完成手术,13例患者共置入26枚螺钉;手术时间60~130min,平均80min;术中出血110~290ml,平均190ml.术中无脊髓、椎动脉损伤等并发症.术后复查CT显示1枚螺钉位置欠佳,螺钉外斜角偏小且上斜角偏大,螺钉部分进入椎管,但未损伤脊髓,未做处理;25枚位置良好.寰枢关节基本复位,固定可靠.术后随访12~60个月,平均18个月,末次随访时VAS评分降至1.0~2.0分,平均1.3分,与术前比较有统计学差异(P<0.05).2例伴颈髓损伤患者的症状均有改善,Frankel分级C级者恢复到D级,D级者恢复到E级.12例患者术后3个月开始出现植骨融合,末次随访时寰枢关节间隙植骨均达到融合;1例患者未见明显植骨融合,但寰枢关节稳定性良好,未出现断钉等并发症.结论:内窥镜辅助下前路经寰枢关节螺钉固定植骨融合术治疗上颈椎不稳是可行的,能取得较好的治疗效果,且在一定程度上克服了传统手术显露困难的缺点,从而减少手术并发症.%Objectives: To evaluate the operation method and clinical outcome of atlantoaxial joint fusion using endoscopy-assisted anterior transarticular screw fixation and bone grafting for upper cervical instability. Methods: 13 cases with upper cervical instability who underwent anterior release

  3. Comparison of expansive pedicle screw and polymethylmethacrylate-augmented pedicle screw in osteoporotic sheep lumbar vertebrae: biomechanical and interfacial evaluations.

    Directory of Open Access Journals (Sweden)

    Da Liu

    Full Text Available BACKGROUND: It was reported that expansive pedicle screw (EPS and polymethylmethacrylate-augmented pedicle screw (PMMA-PS could be used to increase screw stability in osteoporosis. However, there are no studies comparing the two kinds of screws in vivo. Thus, we aimed to compare biomechanical and interfacial performances of EPS and PMMA-PS in osteoporotic sheep spine. METHODOLOGY/PRINCIPAL FINDINGS: After successful induction of osteoporotic sheep, lumbar vertebrae in each sheep were randomly divided into three groups. The conventional pedicle screw (CPS was inserted directly into vertebrae in CPS group; PMMA was injected prior to insertion of CPS in PMMA-PS group; and the EPS was inserted in EPS group. Sheep were killed and biomechanical tests, micro-CT analysis and histological observation were performed at both 6 and 12 weeks post-operation. At 6-week and 12-week, screw stabilities in EPS and PMMA-PS groups were significantly higher than that in CPS group, but there were no significant differences between EPS and PMMA-PS groups at two study periods. The screw stability in EPS group at 12-week was significantly higher than that at 6-week. The bone trabeculae around the expanding anterior part of EPS were more and denser than that in CPS group at 6-week and 12-week. PMMA was found without any degradation and absorption forming non-biological "screw-PMMA-bone" interface in PMMA-PS group, however, more and more bone trabeculae surrounded anterior part of EPS improving local bone quality and formed biological "screw-bone" interface. CONCLUSIONS/SIGNIFICANCE: EPS can markedly enhance screw stability with a similar effect to the traditional method of screw augmentation with PMMA in initial surgery in osteoporosis. EPS can form better biological interface between screw and bone than PMMA-PS. In addition, EPS have no risk of thermal injury, leakage and compression caused by PMMA. We propose EPS has a great application potential in augmentation of

  4. 经皮骶髂螺钉和骶髂关节前路钢板内固定治疗不稳定骨盆骨折的临床疗效比较%Clinical curative effect comparison on percutaneous sacroiliac screws internal fixation and sacroiliac joint anterior plate fixation in the treatment of unstable pelvic fractures

    Institute of Scientific and Technical Information of China (English)

    蔺广生

    2016-01-01

    目的:探讨经皮骶髂螺钉和骶髂关节前路钢板内固定治疗不稳定骨盆骨折的临床疗效。方法选取2012年1月~2014年1月收治的149例不稳定骨盆骨折患者,根据治疗方法将其分成骶髂钢板组和骶髂螺钉组。其中骶髂钢板组74例,给予骶髂关节前路钢板内固定治疗;骶髂螺钉组75例,给予经皮骶髂螺钉治疗。比较两组患者临床资料、手术相关指标、临床疗效以及术后并发症。结果两组患者性别、年龄、致伤原因、合并伤以及Tile分类等资料数据比较差异无统计学意义( P>0.05);骶髂螺钉组患者手术时间、出血量、切口长度以及住院时间[(86.1±11.2)min,(16.7±8.5)mL,(1.7±0.6)cm和(8.7±2.7)d]均显著低于骶髂钢板组患者[(122.3±20.5)min,(516.3±118.7)mL,(15.7±1.5)cm和(17.7±4.8)d,P<0.05];骶髂螺钉组患者骨折复位优良率和功能恢复优良率(97.3%和96.0%)均显著高于骶髂钢板组患者(79.7%和73.0%,P<0.05);骶髂螺钉组患者术后并发症发生率(4.0%)显著低于骶髂钢板组患者(24.3%,P<0.05)。结论经皮骶髂螺钉治疗不稳定骨盆骨折临床疗效显著,且具有出血量小、创伤小、恢复快、术后并发症少等优点,值得临床推广应用。%Objective To investigate clinical efficacy of percutaneous sacroiliac screws internal fixation and sacroiliac joint anterior plate fixation in the treatment of unstable pelvic fractures.Methods From Jan.2012 to Jan.2014,149 cases of unstable pelvic fracture were selected to study.According to the treatment method,all the patients were divided into sacroiliac plate group and sacroiliac screw group.There were 74 patients in the sacroiliac plate group treated with the sacroiliac joint anterior plate internal fixation and 75 patients in the sacroiliac screw group treated with percutaneous sacroiliac screw fixation

  5. Biomechanical comparison of cervical transfacet pedicle screws versus pedicle screws

    Institute of Scientific and Technical Information of China (English)

    LIU Guan-yi; XU Rong-ming; MA Wei-hu; SUN Shao-hua; HUANG Lei; YING Jiang-wei; JIANG Wei-yu

    2008-01-01

    Background Transfacet pedicle screws provide another alternative for standard pedicle screw placement for plate fixation in the Iumbar spine. However, few studies looking at transfacet pedicle screw fixation in the cervical spine are available. Therefore, cervical transfacet pedicle screw fixation and standard pedicle screw fixation techniques were biomechanically compared in this study.Methods Ten fresh human cadaveric cervical spines were harvested. On one side, transfacet pedicle screws were placed at the C3-4, C5-6, and C7-T1 levels. On the other side, pedicle screws were placed at the C3, C5, and C7 levels. The screw insertion technique at each level was randomized for right or left. The starting point for the transfacet pedicle screw insertion was located at the midpoint of the inferolateral quadrant of the lateral mass and the direction of the screw was about 50° caudally in the sagittal plane and about 45° toward the midline in the axial plane. Screws were placed from the inferior articular process, across the facet complex and the pedicle into the body of the caudal vertebra. The entry point for the pedicle screw was located at the midpoint of the superolateral quadrant of the lateral mass, and the direction of the screw was about 45° toward the midline in the axial plane and toward the upper third of the vertebral body in the sagittal plane. After screw placement we performed axial pullout testing.Results All the cervical transfacet pedicle screws and the pedicle screws were inserted successfully. The mean pullout strength for the transfacet pedicle screws was 694 N, while for the pedicle screws 670 N (P=-0.013). In all but six instances (10%), the pedicle screw pullout values exceeded the values for the transfacet pedicle screws; this occurred three times at the C3/C4 level, twice at the C5/C6 level and once at the C7/T1 level. The greatest pullout strength difference at a single level was observed at the C5/C6 level, with a mean difference of 38 N (t

  6. Translaminar facetal screw (magerl′s fixation

    Directory of Open Access Journals (Sweden)

    Rajasekaran S

    2005-01-01

    Full Text Available Translaminar facet screw fixation (TLFS achieves stabilization of the vertebral motion segment by screws inserted at the base of the spinous process, through the opposite lamina, traversing the facet joint, and ending in the base of the transverse process. It is simple, does not require any specialized equipment, and has the advantages of being a procedure of lesser magnitude, lesser operative time, less cost and few complication rate. Recently there is growing interest in this technique to augment the anterior lumbar fusions to achieve global fusion less invasively. In this review article, we discuss the clinical and biomechanical considerations, surgical technique, indications, contraindications and recent developments of TLFS fixation in lumbar spine fusion.

  7. Hollow lag screws combined with reconstruction plates for treatment of high anterior column fracture of the acetabulum with intact true pelvic brim%空心拉力螺钉联合重建钢板治疗真骨盆缘完整的髋臼高位前柱骨折

    Institute of Scientific and Technical Information of China (English)

    周炎; 刘世清; 瞿新丛; 余铃; 廖琦; 黄涛; 赵奇; 张春

    2014-01-01

    目的 探讨真骨盆缘完整的髋臼高位前柱骨折采用空心拉力螺钉联合重建钢板固定的疗效.方法 2009年6月-2012年9月收治真骨盆缘完整的髋臼高位前柱骨折6例,其中挤压伤4例,高处坠落伤2例;参照谭国庆等分型:单纯型4例,粉碎型2例.采用髂股入路先行髋臼顶复位空心拉力螺钉固定,后复位、重建钢板固定髂骨翼及髂嵴.结果 6例术后随访12~24个月,平均18个月.所有患者骨折均愈合,愈合时间12 ~ 18周,平均16周.术后按Matta影像学评定标准,优5例,良1例,优良率100%.末次随访时按Matta改良的Merle d'Aubigne和Postel髋关节功能评分标准,优4例,良2例,优良率100%.术后2例出现股外侧皮神经麻痹,口服神经营养药物2~3个月后均恢复.结论 空心拉力螺钉联合重建钢板治疗真骨盆缘完整的髋臼高位前柱骨折固定可靠,临床疗效满意.%Objective To investigate the clinical effect of high anterior column fracture of the acetabulum with intact true pelvic brim fixed using hollow lag screws plus reconstruction plates.Methods All cases of high anterior column fracture of the acetabulum with intact true pelvic brim treated from June 2009 to September 2012 were included.Crush contributed to injury in 4 cases and high fall to injury in 2 cases.According to Tan Guoqing' s classification,4 cases were classified as simple type and 2 cases comminuted type.All cases were treated through iliofemoral approach to reduce and fix acetabular roof by hollow lag screws firstly,and then fix iliac wing and iliac crest by reconstruction plates.Results Six cases were followed up for mean 18 months (range,12-24 months).Fracture healed after mean 16 weeks (range,12-18 weeks).Radiological results assessed using Matta' s score system were excellent in 5 cases and good in 1 case with good to excellent rate of 100%.At the final follow-up,Merle d' Aubigne and Postel hip score was excellent in 4 cases and good in 2

  8. Experimental biomechanical analysis of standing position in both-column acetabular fractures fixed by anterior reconstruction plate combinated with trans-plate quadrilateral screws%前路钛板加方形区螺钉治疗髋臼双柱骨折的站立位力学分析

    Institute of Scientific and Technical Information of China (English)

    蔡贤华; 吴咏德; 刘曦明; 张红喜

    2013-01-01

    [目的]探讨前路特殊塑形钛板加方形区螺钉治疗髋臼双柱骨折早期站立的可能性.[方法]选取成年防腐保湿处理的全骨盆标本6具,保留韧带及髋关节囊,制作单侧髋臼高位双柱骨折模型,随机先后采用前路特殊塑形钛板加方形区螺钉(B组)及常规塑形钛板加1/3管型钛板(C组)内固定,固定标本于ZWICKZ100电子万能材料试验机上,模拟站立位以400~700 N垂直加载,分别测定完整骨盆(A组)、B组及C组后柱内壁横向位移、髋臼顶纵向位移,并计算刚度.[结果]随着载荷增加,各位移值呈逐渐增加的线性关系,且A组<B组<C组;在生理负荷600N载荷下,横向与纵向位移值均为C组>B组>A组、刚度为C组>B组>A组,C组与B组、A组与C组间差异明显(P<0.05),B组与A组差异无显著意义(P>0.05).[结论]站立位下,前路特殊塑形钛板加方形区螺钉较常规塑形钛板加1/3管型钛板内固定即刻力学性能更为可靠,稳定性与完整骨盆接近,这表明早期站立并不影响前路特殊塑形钛板加方形区螺钉内固定的稳定性.%[ Objective] To explore the standing possibility in the early after both - column acetabular fracture fixed by anterior specially - shaped reconstruction plate combinated with trans - plate quadrilateral screws on cadaver. [ Method] Six Chinese adult wetly pelvic specimens with their ligament and joint capsule of hip joint preserved with antisepsis were made into the model with high both-column acetabular fracture on one side. The fractures were fixed randomly by anterior specially-shaped titanium plate with quadrilateral screws( group B) or conventionally-shaped reconstruction titanium plate with 1/3 tubular titanium plate (group C). To imitate the static standing position of the patient,the specimen fixed on ZWICK-Z100 electronic universal material testing machine received the vertical loading from 400 N to 700 N to measure the transverse displacement of

  9. Clinical comparative analysis on percutaneous sacroiliac screws internal fixation and sacroiliac joint anterior plate fixation in the treatment of unstable pelvic fractures%经皮骶髂螺钉与骶髂关节前方钢板固定治疗不稳定性骨盆骨折的临床疗效分析

    Institute of Scientific and Technical Information of China (English)

    杨雷; 王洪飞; 王中海

    2012-01-01

    目的 探讨经皮骶髂螺钉与骶髂关节前方钢板固定治疗不稳定性骨盆骨折的临床疗效.方法 选取本院2008年1月至2011年6月收治的不稳定性骨盆骨折患者64例,随机分为两组,采用骶髂关节前方钢板固定治疗的患者32例为对照组,采用经皮骶髂螺钉内固定治疗的患者32例为观察组,比较两组患者围术期临床指标、术后Matta评分、术后Majeed功能评分.结果 观察组手术时间、术中出血量、伤口总长度、术后发热时间、住院时间均明显少于对照组,观察组并发症发生率(3.1%)明显低于对照组(21.9%),观察组术后Matta评分总优良率(96.9%)明显高于对照组(81.2%),观察组术后Majeed功能评分总优良率(93.8%)明显高于对照组(75.0%),差异均有统计学意义(P<0.05).结论 经皮骶髂螺钉内固定治疗不稳定性骨盆骨折具有损伤小、出血少、疼痛轻、恢复快等优点,是一种安全有效的微创手术方法,临床疗效明显好于骶髂关节前方钢板固定,术前充分准备及患者积极配合可以大幅降低并发症的发生率,值得临床推广使用.%Objective To investigate clinical efficacy of percutaneous sacroiliac screws internal fixation and sacroiliac joint anterior plate fixation in the treatment of unstable pelvic fractures. Methods Sixty-four patients with unstable pelvic fractures were selected in the hospital from January 2008 to June 2011, which were randomly divided into two groups. The control group (n=32) used sacroiliac joint anterior plate fixation, while the study group (n=32) used percutaneous sacroiliac screw internal fixation for treatment. The perioperative clinical indicators, postoperative Matta score, postoperative Majeed function score of all patients were compared. Results The operation time, intraop-erative blood loss, wound total length, postoperative fever time, duration of hospitalization in the study group were significantly less than those

  10. Modelo simulador para treinamento de punção transpedicular em vertebroplastia percutânea Manikin-type training simulator model for transpedicular puncture in percutaneous vertebroplasty

    Directory of Open Access Journals (Sweden)

    Nitamar Abdala

    2007-08-01

    Full Text Available OBJETIVO: Desenvolver e testar a similaridade de modelo de coluna lombar tipo manequim para treinamento de punção transpedicular em vertebroplastia percutânea. MATERIAIS E MÉTODOS: Foram confeccionadas 30 vértebras lombares à base, principalmente, de metacrilato, gesso e etil-vinil-acetato, a partir de molde de borracha baseado em vértebra humana. Os discos intervertebrais foram feitos com silicone para que houvesse similaridade anatômica e fusão de cinco vértebras. O segmento da coluna foi acondicionado no interior de um manequim coberto por tela de etil-vinil-acetato para que não fosse possível a visualização direta. Foi realizado curso teórico para seis especializandos de radiologia e neurorradiologia, que testaram o modelo para vários parâmetros de similaridade com a realidade, realizando 30 punções transpediculares, em três sessões de dez procedimentos por dia, com intervalo de uma semana entre cada sessão. RESULTADOS: Cada aluno realizou 30 punções transpediculares, porém oito punções foram desconsideradas, pois se observaram problemas de manufatura dos modelos durante estes procedimentos. Após a realização das punções, todos os participantes preencheram o formulário de similaridade, com 100% de respostas positivas em relação à similaridade do modelo. CONCLUSÃO: Foi possível o desenvolvimento de modelo para punção transpedicular com similaridade satisfatória com o ser humano, configurando um instrumento de treinamento de vertebroplastia.OBJECTIVE: To develop and test a model of the human lumbar vertebra for training transpedicular puncture in percutaneous vertebroplasty. MATERIALS AND METHODS: Thirty lumbar vertebra models were constructed from methacrylate, plaster and ethyl-vinyl-acetate, using a rubber mold of human vertebrae. The intervertebral discs were made of silicone to provide anatomical similarity and fusion of five vertebrae. This model of spinal column segment was positioned within a

  11. Cervicoplastia anterior Anterior cervicoplasty

    Directory of Open Access Journals (Sweden)

    Lucas Gomes Patrocínio

    2004-10-01

    Full Text Available Muitos pacientes buscam correção estética da frouxidão da pele do pescoço, depósito de gordura na região submentoneana ou bandas de platisma. Em grande parte dos casos a ação medial, via cervicoplastia anterior é necessária. OBJETIVO: Demonstrar a casuística e avaliar os resultados e complicações com a técnica de cervicoplastia anterior no Serviço de Otorrinolaringologia da Universidade Federal de Uberlândia. FORMA DE ESTUDO: Relato de série. PACIENTES E MÉTODOS: Quarenta e dois pacientes, entre 39 e 65 anos de idade, sendo 40 (95,2% do sexo feminino e 2 (4,8% do masculino, foram submetidos a cervicoplastia anterior. Retrospectivamente foram avaliados resultados e complicações. RESULTADOS: Destes, 34 apresentaram resultados satisfatórios, 4 apresentaram déficit estético notado somente pelo cirurgião, 3 apresentaram déficit estético notado somente pelo paciente e 1 apresentou déficit estético necessitando cirurgia revisional. Ao estudo fotográfico, todos os pacientes apresentaram melhora do perfil cervical, redução das bandas de platisma e da frouxidão da pele, estabilização da musculatura cervical e acentuação do ângulo cervicomental, em graus variados. Houve complicação em 2 casos (discreto serohematoma e cicatriz um pouco alargada. CONCLUSÃO: A cervicoplastia, associada ou não à tração lateral pela ritidoplastia, é uma técnica que produz resultados satisfatórios na grande maioria dos casos.Many patients look for aesthetic correction of the laxity of neck skin, submandibular fat deposit or platisma bands. In a large part of the cases, medial action, through anterior cervicoplasty is necessary. AIM: To demonstrate the casuistic and to evaluate the results and complications with anterior cervicoplasty technique in the Otorhinolaryngology Service of the Federal University of Uberlândia. STUDY DESIGN: Serie report. PATIENTS AND METHODS: Forty-two patients, between 39 and 65 years of age, being 40 (95

  12. Fixação transpedicular da coluna toraco-lombo-sagrada: análise de 124 parafusos

    Directory of Open Access Journals (Sweden)

    Eunice Carvalho

    2013-01-01

    Full Text Available OBJECTIVO: Avaliar a técnica free hand de colocação de parafusos transpediculares na coluna torácica, lombar e sagrada. MÉTODOS: Avaliação clínica e imagiológica (tomografia computorizada de 25 pacientes (13 mulheres e 12 homens submetidos a instrumentação vertebral num total de 124 parafusos transpediculares aplicados, utilizando a técnica free hand. Os parafusos foram inseridos de T11 a S1, e a maioria destes foram colocados nos níveis L4, L5 e S1. RESULTADOS: 94% dos parafusos transpediculares estavam correctamente colocados no pedículo. Verificou-se que 6% (7 parafusos estavam mal colocados e destes apenas dois violavam a cortical inferomedial, um destes apresentava uma perfuração inferior a 2 mm e o outro entre 2 e 4 mm. Nenhum dos pacientes seguidos apresentou complicações associadas ao incorrecto posicionamento dos parafusos. CONCLUSÃO: A técnica free hand é segura na instrumentação da coluna torácica e lombo-sagrada.

  13. 颈前路单枚空心螺钉治疗Ⅱ型齿状突骨折失误15例分析%Intraoperative mismanagement in anterior single-screw fixation of odontoid fractures: an analysis of 15 cases

    Institute of Scientific and Technical Information of China (English)

    吴玉杰; 贾连顺; 傅智轶; 金文杰; 胡小鹏

    2011-01-01

    Objective To analyze intraoperative mismanagements in anterior single-screw fixation of odontoid fractures.Methods From April 2002 to July 2010, intraoperative mismanagements happened in the treatment of 15 cases of fresh odontoid fracture with anterior single-screw fixation under C-arm fluoroscopy.They were 10 men and 5 women, aged from 22 to 65 years (average, 37 years).All the fractures were Anderson-D' Alonzo type Ⅱ.The mismanagements were characterized to find out their reasons.Results The mean follow-up time was 13.4 months (range, 6 to 47 months).All the fractures healed in an average of 14.5 week (range, 12 to 34 weeks) after operation, no severe complications were found.The intraoperative mismanagements could be elassified into 3 kinds.In the first kind, the guide pin was driven through the odontoid bone into the cranial cavity in 3 cases, resulting in one death due to serious injury to the medullary bulb.In the second kind, malreduction happened in 5 cases due to intraoperative displacement of the fracture.In the third kind, poor position and fixation of the screw happened in 7 cases because of enlargement of the screw canal after repeated correction of the guide pin direction.Conclusions The intraoperative mismanagements in anterior single-screw fixation of odontoid fractures were mostly caused by careless surgeons who made their operative assessments and plans before they read the X radiographs of their patients carefully or before they had been familiar with the operative instruments.Secondly, some mismanagements were caused by intraoperative accidents, most of which, however, could have been avoided by careful preoperative preparation and meticulous operative maneuvers.%目的 分析颈前路加压螺钉内固定治疗Ⅱ型齿状突骨折失误的原因及对策.方法 分析2002年4月至2010年7月在C型臂X线机监视下行前路加压螺钉内固定治疗中出现失误的15例新鲜Ⅱ型齿状突骨折患者资料,男10例,女5例;年龄22

  14. 经前路椎体次全切钛笼置入锁定钢板螺丝钉内固定治疗相邻两节段脊髓型颈椎病%Adjacent Two Segments Anterior Subtotal Titanium Cage into the ;Locking Plate Screw Fixation for the Treatment of Cervical Spondylotic Myelopathy

    Institute of Scientific and Technical Information of China (English)

    青祖宏; 刘明; 高巍; 何蔚; 刘杨; 李永焕

    2013-01-01

    Objective To summarize the clinical efficacy of the anterior corpectomy cut with titanium cage and locking plate screw fixation for the treatment of two adjacent cervical spondylotic myelopathy.Method August 2010~December 2012,Anterior corpectomy cut with titanium cage and locking plate screw fixation for the treatment of adjacent two segments cervical spondylotic myelopathy 25 cases,including 18 men and 7 women patients,aged 33~75 years,mean 56.5 years.In 25 patients with varying degrees of symptoms of spinal cord compression. There are 9 cases(C4/C5). There are 15 cases(C5/C6).There are 1 case(C6/C7).Observed lateral cervical spine,cervical hyperextension flexion X-rays and cervical MR, before and after surg ery and follow-up phase,so as to learn spinal cord compression,cervical stability and postoperative cervical height,curvature,titanium cage plate screw position and cervical fusion. Compared preoperative to postoperative and follow-up,pain visual analog scale (VAS) and the Japan Orthopaedics Association (JOA) pain score.Results Operative time (120±30) min,blood loss (150±50)ml.The surgery does not appear related complications.The followed up time are 2~24 months (mean 12.5 months). Nerve function significantly improved.JOA score increased from preoperative 6.2±1.1 to the last follow-up 14.3±1.5,with an average improvement rate was (82.3±11.4)%.VAS average score is 2.1 points.The follow-up period is not found that the titanium cage shift,loose screws and lesion spinal cord compression phenomenon.Conclusion Anterior corpectomy cut with titanium cage and locking plate screw fixation for the treatment of two adjacent segments of cervical spondylotic myelopathy,effectively relieve nerve compression of the spinal cord,quickly restored cervical curvature and height,reconstruction of spinal stability,shorter operative time,less bleeding, and less damage.It has created favorable conditions for the rehabilitation of neurological function in patients,which is an

  15. Intrafix与界面螺钉在前交叉韧带重建中的生物力学研究%Biomechanical evaluation of tendon graft fixation at the tibial site in anterior cruciate ligament reconstruction with intrafix and bioabsorbable interference screw

    Institute of Scientific and Technical Information of China (English)

    王俊良; 刘玉杰; 王爱媛; 杨玉明; 李海峰; 李众利; 王志刚

    2009-01-01

    目的 探讨胭绳肌腱移植重建前交叉韧带(ACL)胫骨端界面螺钉与Intrafix固定的生物力学.方法 新鲜冰冻尸体膝关节标本14具,采用四股腘绳肌腱移植重建ACL,胫骨端分别采用可吸收界面螺钉(n=7)和Intrafix(n=7)固定,测试最大载荷、100 kg·m·s-2和400 kg·m·s-2位移、抗拉刚度、失败模式等数据并进行统计学分析.结果 Intrafix固定组的最大载荷大于可吸收界面螺钉组,两组间差异有统计学意义(t=0.003,P0.05),抗拉刚度两组间差异无统计学意义(t=0.0967,P>0.05).结论 四股胭绳肌腱移植重建ACL,胫骨端采用可吸收界面螺钉和Intrafix固定均可满足ACL初期固定强度的需求;Intrafix固定强度大于可吸收界面螺钉.%Objective The fixation strength of the hamstring tendon graft on the tibial side is considered the weak point in anterior eruciate ligament (ACL) reconstruction. This work tested the hypotheses that some of these devices will resist graft slippage under loads better than others, and that some will have higher ultimate strength than others. Methods Fourteen flesh frozen human cadaver knees underwent fixation of the hamstring tendon harvested from the knee to be used as graft material to reconstruct the ACL and were divided into two equal groups based on the fixation methods: bioabsorbable interference screw group and Intrafix group. A MTS 858 MiniBionix Ⅱ testing machine was used to carry out tensile testing under an axial load parallel to the tibial tunnel with a velocity of 10 mm/min. Ultimate failure load, displacement of 100N, displacement of 4OON, stiffness and mode of failure were recorded respectively. Results The maximum load for the lntrafix fixation group was (719. 094 ± 160. 478) kg · m · s-2, significantly higher than that of the bioabsorbable interference screw fixation group [(476. 640 ± 64. 226) kg · m · s-2, P 0. 05], and the stiffness of the Intratix fixation group was (96. 770 ±36. 848) kg · m-1

  16. Comparison of the effects on percutaneous sacroiliac joint screw fixation and anterior sacroiliac joint plate fixation in the treatment of unstable pelvic fractures%经皮骶髂关节螺钉与骶髂关节前方钢板固定治疗不稳定型骨盆骨折的效果比较

    Institute of Scientific and Technical Information of China (English)

    丁涛

    2016-01-01

    Objective To investigate the efficacy of percutaneous sacroiliac joint screw fixation and anterior sacroiliac joint plate fixation in the treatment of unstable pelvic fractures. Methods Forty cases of patients with unstable pelvic fractures were divided into two groups according to odd and even numbers. The control group (odd numbers, 20 cases) was given anterior sacroiliac joint plated fixation, while the observation group (20 cases) was given percutaneous sacroiliac joint screw. The efficacy of the two groups were evaluated with perioperative indexes, Majeed scores and complications during 6 months follow-up. Results The operative time, blood loss and hospitalization time of the observation group were significantly superior to those of the control group (P<0.05); the excellent rate of the observation group was significantly higher than that of the control group (P<0.05); during follow-up, the complication rate of the observation group was lower than that of the control group (P<0.05). Conclusion Percutaneous sacroiliac joint screw fixation has a good therapeutic effect on unstable pelvic fracture, with less operation time and fewer complications, so as to promote the recovery of patients, which is worthy of clinical application.%目的:探讨经皮骶髂关节螺钉与骶髂关节前方钢板固定治疗不稳定型骨盆骨折的疗效。方法选取40例不稳定型骨盆骨折患者,按住院单双号分为两组。对照组(20例)给予骶髂关节前方钢板固定治疗,观察组(20例)给予经皮骶髂关节螺钉治疗,观察并记录两组围手术期指标、Majeed评分及随访6个月期间并发症发生情况。结果观察组手术时间、术中出血量、住院时间均明显优于对照组( P<0.05);观察组患者手术治疗的优良率明显高于对照组( P<0.05),随访期间,观察组患者并发症发生率明显低于对照组( P<0.05)。结论经皮骶髂关节螺钉手术对不稳定型骨盆骨折

  17. Screw bondgraph contact dynamics

    NARCIS (Netherlands)

    Visser, Martijn; Stramigioli, Stefano; Heemskerk, Cock

    2002-01-01

    This paper presents an elegant contact dynamics model in screw bondgraph form. It can model the contact between any two objects of finite curvature. It does so by defining a Gauss frame on the surfaces of both objects in the points that are closest to each other. Then it describes how the Gauss fram

  18. Radiological studies on the best entry point and trajectory of anterior cervical pedicle screw in the lower cervical spine%下颈椎前路椎弓根螺钉最佳进钉点和进钉方向的影像学研究及其临床运用

    Institute of Scientific and Technical Information of China (English)

    赵刘军; 徐荣明; 华群; 马维虎; 蒋伟宇; 朱彦召

    2012-01-01

    Objective:To explore the best entry point and trajectory of anterior cervical screw in the cervical screw by radiological studies,and provide reference for clincal application. Methods:From January 2008 to December 2010,50 patients were scanned by cervical CT and confirmed no obvious defect of lower cervical spine. Of them, 27 cases were males and 23 were females,ranged the age from 38 to 83 years ( mean 58.5 years). On horizontal axis,the camber angle of C3-C7 anterior lower cervical pedicle of vertebral arch axis (α) and distance between (axial length, AL) of anterior cervical pedicle axial line was measured from C3 to C7- Vertebral were divided into four areas, and from measured side of pedicle of vertebral began to record, orderly 1 to 4, the area of pedicle vertebral arch intersert into vertebral were recorded. On sagittal view, the head or tail angle(β)and length (sagittal length,SL)of anterior cervical pedicle axial line was also measured from C3 to C7- Vertebral were divided into four areas,and from measured side of pedicle of vertebral began to record, orderly 1 to 4, the area of pedicle verte-bralarch arch intersert into vertebral were recorded. The above data were statistically analyzed to find the best entry point and trajectory of anterior cervical screw in the cervical screw and insert pedicle screw. Results:The lateral angle of lower cervical spine was 38° to 45° on transverse plane,C3 to C5 increasing gradually,C5 to C7 decreasing. On sagittal view,C3,C4 pedicle were head tulting, C5 were basic level, C6, C7 were tail. C3 to C5 decreasing gradually, C5 to C7 increasing gradually. C3 to C7 in AL and SL increased gradually. On horizontal axis, the intersection of C3, C4 and C5 were in the second area, the number of C6 in the second and third area were the same,but C7 were in the third area. The intersection in the first and forth area were less. On sagittal view, the intersection of C3, C4 and C5 were in the first area, the number of C6 in third

  19. 上颈椎3D打印模型的精确性验证及在前路枕-寰-枢螺钉内固定术中的可行性%3D-printed upper cervical models: accuracy validation and feasibility study into anterior occiput-to-axis screw fixation on them

    Institute of Scientific and Technical Information of China (English)

    吴爱悯; 金海明; 车灿文; 吴立军; 林仲可; 倪文飞; 徐华梓; 池永龙; 王向阳

    2016-01-01

    Objective To validate the accuracy of 3D-printed upper cervical models and investigate the feasibility of use of the models in anterior occiput-to-axis screw fixation, in an attempt to provide a protocol of pre-operative plan for surgeons.Methods Forty-five adult atlantoaxial CT scans were obtained, imported into Mimics software for 3 D reconstruction, successively imported into 3 D printer to print the 3D models.Fourteen parameters were measured on both imaging system and 3D-printed models to validate the accuracy of 3D-printed models.Thirty upper cervical CT data were obtained and imported into Mimics software for 3D reconstruction.Cylinders in 1.75 mm radius were drawn to simulate the trajectory of anterior occiput-to-axis screw fixation.Anteroposterior view of the minimum lateral angle (α1) and maximum lateral angle (α2) and lateral view of the minimum posterior angle (β1) and maximum posterior angle (β2) were measured.Mean value of α1 and α2 was calculated as α3 and mean value of β1 and β2 as β3.Meanwhile, the 3D models were printed, and an angle guide device was used to introduce the anterior occiput-to-axis screws into the 3D models in reference to the angles of α3 and β3.Anteroposterior view of lateral angle (α4) and lateral view of posterior angle (β4) were measured.Differences in α3 vs.α4 and β3 vs.β4 were compared.Results All above 14 parameters did not differ significantly between radiographic images and 3D-printed models (P > 0.05).Intraclass correlation coefficient (ICC) values of 13 parameters were > 0.800.On the 3D digital models, the α3 was (12.6 ± 3.7) ° (left) and (12.0 ±4.2) ° (right), and the β3 was (23.9 ± 4.8) ° (left) and (23.4 ± 4.9) ° (right).On the 3 D-printed models, the α4 was (12.0 ± 4.1) ° (left) and (12.3 ± 4.1) ° (right), and β4 was (23.4 ± 4.2) ° (left) and (22.8 ± 4.4)° (right).There were no significant differences in both comparisons of α3 vs.α4 and β3 vs.β4 (P > 0.05).Conclusions

  20. Arthroscopic fixation with screws versus sutures for anterior cruciate ligament tibial avulsion fractures%关节镜下螺钉与缝线固定前交叉韧带胫骨止点撕脱骨折的疗效比较

    Institute of Scientific and Technical Information of China (English)

    王庆; 黄华扬; 张涛; 沈洪园; 郑小飞; 李凭跃; 区永亮

    2015-01-01

    Objective To compare the curative effects between arthroscopic screw and suture fixations for anterior cruciate ligament (ACL) tibial avulsion fractures.Methods From November 2007 to November 2012,41 patients with ACL tibial avulsion fracture underwent arthroscopy at our department.They were 32 males and 9 females,8 to 43 years of age (average,18.3 years).By the Meyers-McKeever-Zaricznyj classification,12 cases were type Ⅱ and 29 type Ⅲ.There were 19 cases in the screw fixation group,including 14 males and 5 females,9 to 42 years of age (average,18.9 years).The suture fixation group had 22cases,including 16 males and 6 females,8 to 43 years of age (average,17.8 years).Operation time,knee range of motion (ROM),case of flexion contracture,Lysholm score,international knee documentation committee (IKDC) score,and side-to-side mobile difference by KT-2000 were evaluated.The 2 groups were similar in age,gender,fracture type and time from injury to surgery (P > 0.05).Results The operation time for the suture fixation group (58.9 ±6.7 min) was significantly longer than that for the screw fixation group (51.6±6.2 min) (P < 0.05).There were no significant differences between the 2 groups regarding the Lysholm score (96.2 ± 2.83 for the screw fixation group versus 95.5 ± 2.6 for the suture fixation group),the IKDC score (91.4 ± 6.4 for the screw fixation group versus 88.1 ± 7.5 for the suture fixation group),the side-to-side mobile difference by KT-2000 (2.7 ± 2.6 mm for the screw fixation group versus 2.8 ± 2.7 mm for the suture fixation group (P < 0.05).Flexion contracture of ≥ 5° occurred in 3 cases in the screw fixation group and 2 cases in the suture fixation group,showing no significant difference (P > 0.05).Conclusions In treatment of ACL tibial avulsion fractures of types Ⅱ and Ⅲ,there is no significant difference between arthroscopic screw fixation and suture fixation,because both methods can achieve good stability and functional recovery

  1. Late vertebral body fracture after lumbar transpedicular fixation. Report of three cases.

    Science.gov (United States)

    Missori, Paolo; Ramieri, Alessandro; Costanzo, Giuseppe; Peschillo, Simone; Paolini, Sergio; Miscusi, Massimo; D'Andrea, Giancarlo; Delfini, Roberto

    2005-07-01

    Late-onset vertebral body (VB) fracture after lumbar transpedicular fixation has not been previously described in the literature. The authors present three cases in which VB fracture occurred several months after posterolateral fixation in patients with degenerative disease or traumatic injury. The authors suggest that postoperative osteopenia, modified load-sharing function, and intravertebral clefts were responsible for the fractures. Two women and one man were evaluated at a mean follow-up interval of 3 months. Two patients suffered recurrent lumbar pain. Radiography and magnetic resonance imaging revealed fracture of some of the instrumentation-treated VBs. These two patients underwent surgical superior or inferior extension of instrumentation. The third, an asymptomatic patient, received conservative management. The two patients who underwent reoperation made complete recoveries, and there was no evidence of further bone collapse in any case. The authors speculate that alterations in the VBs may occur following application of spinal instrumentation. In rare cases, the device can fracture and consequently lead to recurrent lumbar back pain. Recovery can be achieved by extending the instrumentation in the appropriate direction.

  2. 脊柱前路内固定器系统与脊柱后路椎弓根钉棒系统治疗腰椎爆裂性骨折的疗效比较%Effect of anterior internal fixation and posterior pedicle screw fixation in the treatment of lumbar burst fractures

    Institute of Scientific and Technical Information of China (English)

    张建新; 李玉明; 张苏斌; 吕曦

    2016-01-01

    Objective To compare the effect of anterior internal fixation and posterior pedicle screw fixa-tion in the treatment of lumbar burst fractures.Methods Thirty-three patients( the anterior group) with burst frac-ture of lumbar spine treated by anterior internal fixation system in our hospital from Feb.2012 to Dec.2013 were se-lected.Fifty-four patients ( the posterior group) treated by posterior pedicle screw rod system fixation were also ret-rospectively analyzed.The differences in operation time, intraoperative blood loss,loss of Cobb' s angle,Japanese Orthopaedic Association ( JOA) Scores,anterior height ratio of the vertebral body and score by American Spinal In-jury Association (ASIA) between the two groups were compared.Results The operation time of (178.8 ±55.2) min and the intraoperative blood loss of ( 750.9 ± 85.2 ) mL in the anterior group were both significantly higher than those of the posterior group[(149.3 ±38.6)min,(414.3 ±67.8)mL] and the difference was statistically sig-nificant(P0.05).After 1 year of operation,the JOA scores of the two groups were significantly improved and the difference was statistically significant(P0.05) .Conclusion The results of the two methods in the treatment of lumbar burst frac-ture are both satisfactory.The disadvantage of the posterior group is the large loss of Cobb angle correction and the disadvantage of the anterior group is the surgical trauma.Individualized consideration should be given to the factors such as patients' surgical tolerance.%目的 研究对比脊柱前路内固定器系统内固定及脊柱后路椎弓根钉棒系统内固定治疗腰椎爆裂性骨折的效果差异.方法 笔者选取2012年2月~2013年12月采用前路内固定器系统内固定治疗的33例腰椎爆裂性骨折患者(前路组)、后路椎弓根钉棒系统内固定治疗的54例患者(后路组)进行回顾性分析,对比两组患者的手术时间、术中出血量、Cobb角丢失、日本矫形外科协会(JOA)评分

  3. NUT SCREW MECHANISMS

    Science.gov (United States)

    Glass, J.A.F.

    1958-07-01

    A reactor control mechanism is described wherein the control is achieved by the partial or total withdrawal of the fissile material which is in the form of a fuel rod. The fuel rod is designed to be raised and lowered from the reactor core area by means of two concentric ball nut and screw assemblies that may telescope one within the other. These screw mechanisms are connected through a magnetic clutch to a speed reduction gear and an accurately controllable prime motive source. With the clutch energized, the fuel rod may be moved into the reactor core area, and fine adjustments may be made through the reduction gearing. However, in the event of a power failure or an emergency signal, the magnetic clutch will become deenergized, and the fuel rod will drop out of the core area by the force of gravity, thus shutting down the operation of the reactor.

  4. ROTARY SCREW SYSTEMS IN CEMENT

    OpenAIRE

    2016-01-01

    The article presents results of research of rotary-screw systems in relation to the creation of rotary kilns for the annealing of-cuttings in the preparation of cement clinker. Using the proposed design, in comparison with known designs of similar purpose, it significantly improves performance, reduces size and power consumption through the use of rotary screw systems in the form of screw rotors and drums made hollow with sidewalls assembled from separate strips or plates of different geometr...

  5. 颈后路多节段椎弓根螺钉内固定术与颈前路钢板内固定术治疗Hangman骨折疗效对比分析%The Efficacy Comparison of Internal Fixation by Multilevel Pedicle Screw in Posterior and Internal Fixation by Steel Plate in Anterior on Treating ;Hangman Fracture

    Institute of Scientific and Technical Information of China (English)

    李军

    2014-01-01

    目的:观察比较Hangman骨折采用颈后路多节段椎弓根螺钉内固定术与颈前路钢板内固定术的疗效。方法:选取笔者所在医院2010年6月-2013年6月收治的Hangman骨折患者45例,按照随机数字表法分成颈后路组23例和颈前路组22例。比较两组患者手术时间及术中出血量,手术治疗产生的并发症,术后骨折的痊愈程度及恢复脊髓功能的情况。结果:两组患者手术时间、术中出血量、术后骨折痊愈的程度及恢复脊髓功能的情况比较差异均无统计学意义(P>0.05)。颈后路组的并发症总发生率(4.35%)明显低于颈前路组的并发症总发生率(31.82%),两组比较差异有统计学意义(P0.05).The overall incidence of complications in posterior group(4.35%) was significantly lower than anterior group(31.82%),and the difference between the two groups was statistically significant(P<0.05).Conclusion:The ideal method for treating Hangman fracture is internal fixation by multilevel pedicle screw in posterior.

  6. Catheter-directed percutaneous transpedicular C2/C3 vertebroplasty in a patient with fibrous dysplasia using seldinger technique.

    Science.gov (United States)

    Christoforidis, G; Dang, D; Gabriel, J

    2006-09-01

    A 35-year-old man with polyostotic fibrous dysplasia and a massively enlarged skull presented with Lhermitte sensations due to an unstable, mulitseptated, lytic C2/3 vertebral body complex. Enlarged extracranial vasculature made open surgery a high-risk option and limited percutaneous access. A 5F catheter was directed by using a guidewire into the C2/C3 vertebral body complex via a transpedicularly placed biopsy cannula to ensure polymethylmethacrylate deposition throughout the lytic compartments of the vertebral body complex.

  7. Combined anterior C2,3 reduction and fusion with posterior compressive C2 pedicle screw fixation for the treatment of unstable Hangman's fractures:16 eases review%第2、3颈椎前路融合联合第2颈椎椎弓根固定治疗不稳定Hangman骨折

    Institute of Scientific and Technical Information of China (English)

    谢宁; 倪斌; 陈德玉; 叶晓健; 肖建如; 袁文

    2008-01-01

    Objective To determine the outcome of combined anterior C2,3 reduction and fusion with Dosterior compressive C2 pedicle screw fixation for the management of unstable Hangman's fractures.Methods Sixteen cases of unstable Hangman's fractures were retrospectively reviewed through X-ray,MRI and three dimensional CT scans. Pre- and postoperative radiographs were measured for translation and angulation of C2,3 Skull traction under extension poison was conducted in all the patients right after their admission.Then anterior C2,3 discectomy followed by interbody fusion,either with iliac autograft or with box cage,and locking plate fixation were performed in each case.Because unsatisfied reduction,mainly residual large fracture gap or kyphosis,was found by the C-arm fluoroscopy during operations,posterior compressive C,pediele screw fixation was performed in one stage.According to the Levine-Edwards classification,there were 12 cases of type Ⅱ,2 of type Ⅱ a and 2 of type Ⅲ in this group.Results Follow-up ranged 6-38 months,averaged 26 months.Facture union and bone graft fusion were completed in an average of 4 months after operation.Complaints of neck pain and numbness of limbs disappeared in all patients after surgery,but range of neck motion decreased compared with normal people. Translation of C2 decreased from(4.2±1.4)mm preoperatively to(2.3±1.1)mm postoperatively,while angulation of C2,3 decreased from 8.6°±2.1° Dreoperativelv to 2.6°±1.0°postoperatively. Both have statistical significance(P<0.05). No implant failure or infection was observed.Conclusions The classification of Hangman's fracture should be modified in combination with MRI and CT scans to determine the stability of the fracture. Combined anterior C2,3 reduction and fusion with posterior compressive C2 pedicle screw fixation is the treatment of choice for patients with unstable Hangman's fractures.%目的 探讨前路C2,3复位融合联合C2椎弓根钉加压固定方法治疗

  8. 骶髂关节前路钢板螺钉固定手术安全区的应用解剖学研究%The surgical safe zone of the anterior plate and screw fixation on sacroiliac joint: applied anatomy

    Institute of Scientific and Technical Information of China (English)

    刘佳; 孙善全; 倪卫东; 蒋电明; 高仕长

    2012-01-01

    Objective To explore the surgical safe zone of the anterior plate and screw fixation for treating sacroiliac joint fracture and dislocation. Methods 15 normal pelvic specimens were used. The horizontal distances from L4, L5 anterior roots to the sacroiliac joint, the vertical distances from U4, L5 roots to sacral wing, the distances from the intervertebral foreman of L4, Ls to the rim of true pelvis, and the diameter of the L4, L5 roots were measured respectively. On two dimensional pelvic coronal reconstruction images, the angle between sacroiliac joint and sagittal-plane, the width of the sacrum were tested. Results The horizontal distance from the lateral side of the L4, L5 roots to the sacroiliac joint gradually diminished from the top to the bottom, with the widest of (2.1±0.2)and (2.7±0.2 )cm respectively, and the narrowest of (1.2±0.2)cm and (1.5±0.2 )cm respectively. The vertical distances between the L, root and the sacrum also diminished gradually from the intervertebral foramen to the rim of the pelvis. The length of the L4 and L5 roots were( 7.4+0.8 )cm and 3.9±0.5 )cm, and the diameters (2.7±0.8 )mm and (7.3±1.4 )mm respectively. On CT reconstruction images, the angle between sacroiliac joint and sagittal plane was about 30°, and the distance from the sacroiliac joint to the lateral side of the spinal canal changed from 3.3cm to 2.3cm, the horizontal distance from the sacroiliac joint to the lateral side of the intervertebral foramen was about 2cm. Conclusions The surgical safe zone of the anterior plate and screw fixation for treating sacroiliac joint fracture and/or dislocation can be defined as the follows: the upper and lower plates places on the upper third of the sacroiliac joint, with the limited exposure range of 2.5cm, or the middle third of the sacroiliac joint, with the limited exposure range of 1.5cm. The screw should be inserted with introversional angle of 300.%目的 通过对骶髂关节周围解剖和CT重建进行研究,明

  9. Fixation strength of biocomposite wedge interference screw in ACL reconstruction: effect of screw length and tunnel/screw ratio. A controlled laboratory study

    Directory of Open Access Journals (Sweden)

    Herrera Antonio

    2010-06-01

    Full Text Available Abstract Background Primary stability of the graft is essential in anterior cruciate ligament surgery. An optimal method of fixation should be easy to insert and provide great resistance against pull-out forces. A controlled laboratory study was designed to test the primary stability of ACL tendinous grafts in the tibial tunnel. The correlation between resistance to traction forces and the cross-section and length of the screw was studied. Methods The tibial phase of ACL reconstruction was performed in forty porcine tibias using digital flexor tendons of the same animal. An 8 mm tunnel was drilled in each specimen and two looped tendons placed as graft. Specimens were divided in five groups according to the diameter and length of the screw used for fixation. Wedge interference screws were used. Longitudinal traction was applied to the graft with a Servohydraulic Fatigue System. Load and displacement were controlled and analyzed. Results The mean loads to failure for each group were 295,44 N (Group 1; 9 × 23 screw, 564,05 N (Group 2; 9 × 28, 614,95 N (Group 3; 9 × 35, 651,14 N (Group 4; 10 × 28 and 664,99 (Group 5; 10 × 35. No slippage of the graft was observed in groups 3, 4 and 5. There were significant differences in the load to failure among groups (ANOVA/P Conclusions Longer and wider interference screws provide better fixation in tibial ACL graft fixation. Short screws (23 mm do not achieve optimal fixation and should be implanted only with special requirements.

  10. A screwing device for handling and assembly of micro screws

    DEFF Research Database (Denmark)

    Gegeckaite, Asta; Hansen, Hans Nørgaard; Eriksson, Torbjörn Gerhard

    2007-01-01

    Nowadays, the application of specially designed handling devices in micro technology is an important topic and a necessity for the industry. Conventional methods for screwing can not be applied directly to micro screws. This is caused by the 3D micro object geometry and dimensions which inducing ...

  11. 微创后路经皮椎弓根螺钉内固定修复单纯前中柱损伤的急性胸腰椎骨折:回顾性、自身前后对照临床试验方案%Posterior percutaneous pedicle screw fixation for acute thoracolumbar vertebral fractures with simple anterior spinal column injury:study protocol for a retrospective, self-controlled trial

    Institute of Scientific and Technical Information of China (English)

    梁磊; 刘文德; 吴一凡; 孙小航; 丁俊杰

    2016-01-01

    访的客观数据。%BACKGROUND:Posterior pedicle screw fixation is commonly used for thoracolumbar fracture. However, associated disadvantages include severe trauma, extensive bleeding, long rehabilitation time, and long postoperative duration of intractable lumbar stiffness and low back pain. Percutaneous pedicle screw external fixation can reduce injury caused by screw insertion into the paraspinal muscles;particularly in acute thoracolumbar vertebral compression fracture with simple anterior spinal column injury. We hypothesized that minimal y invasive posterior percutaneous pedicle screw fixation for acute thoracolumbar vertebral fractures with simple anterior spinal column injury would exhibit good curative effects. OBJECTIVE:To retrospectively analyze the curative effects of minimal y invasive posterior percutaneous pedicle screw fixation on acute thoracolumbar vertebral fractures with simple anterior spinal column injury. METHODS:This retrospective, single-center, self-control ed trial was performed in PLA 153 Central Hospital, Zhengzhou, Henan Province, China. Thirty-two patients with acute thoracolumbar vertebral fracture with simple anterior spinal column injury (22 males and 10 females, average age 34.7 years, range 25-47 years) were included. Al patients underwent minimal y invasive posterior percutaneous pedicle screw internal fixation and were fol owed up for 3 months. The primary outcome measure was the Cobb angle of the injured vertebral body before, immediately after, and 3 months after internal fixation, which was used to investigate the change in the thoracolumbar spine curvature. The secondary outcome measures included:the anterior height of the injured vertebral body and radiographic findings before and immediately after internal fixation and at the last fol ow-up (to evaluate the recovery of thoracolumbar vertebral fracture), operation time, intraoperative blood loss, duration of hospitalization, and incidence of adverse events 3 months after internal fixation. The study protocol had been

  12. The pullout performance of pedicle screws

    CERN Document Server

    Demir, Teyfik

    2015-01-01

    This brief book systematically discusses all subjects that affect the pullout strength of pedicle screws. These screws are used in spinal surgeries to stabilize the spine. The holding strength of the pedicle screw is vital since loosening of the pedicle screws can cause revision surgeries. Once the pedicle screw is pulled out, it is harder to obtain same stabilization for the fused vertebrae. The book reviews the effect of screw designs, application techniques, cement augmentation, coating of the screw and test conditions on the pullout strength. The studies with finite element analysis were also included.

  13. Carbon nanotube Archimedes screws.

    Science.gov (United States)

    Oroszlány, László; Zólyomi, Viktor; Lambert, Colin J

    2010-12-28

    Recently, nanomechanical devices composed of a long stationary inner carbon nanotube and a shorter, slowly rotating outer tube have been fabricated. In this paper, we study the possibility of using such devices as nanoscale transducers of motion into electricity. When the outer tube is chiral, we show that such devices act like quantum Archimedes screws, which utilize mechanical energy to pump electrons between reservoirs. We calculate the pumped charge from one end of the inner tube to the other, driven by the rotation of a chiral outer nanotube. We show that the pumped charge can be greater than one electron per 360° rotation, and consequently, such a device operating with a rotational frequency of 10 MHz, for example, would deliver a current of ≈1 pAmp.

  14. Do Newer-Generation Bioabsorbable Screws Become Incorporated into Bone at Two Years After ACL Reconstruction with Patellar Tendon Graft?

    Science.gov (United States)

    Cox, Charles L.; Spindler, Kurt P.; Leonard, James P.; Morris, Brent J.; Dunn, Warren R.; Reinke, Emily K.

    2014-01-01

    Background: Bioabsorbable interference screws are used frequently for graft fixation in ACL (anterior cruciate ligament) reconstruction. The resorption properties of many available screws that are marketed as bioabsorbable are not well defined. The CALAXO (Smith & Nephew Endoscopy) and MILAGRO (DePuy Synthes) bioabsorbable screws contain polymers of poly(lactic-co-glycolic acid) (PLGA) plus additives to encourage osseointegration over time. The purpose of this study was to evaluate radiographic and magnetic resonance imaging (MRI) properties and compare patient-reported outcomes at a minimum of two years of follow-up after ACL reconstruction using CALAXO or MILAGRO bioabsorbable interference screws. Methods: A cohort of patients who underwent ACL reconstruction in which the fixation used was either CALAXO or MILAGRO screws returned for repeat radiographs for evaluation of tunnel widening, repeat MRI for evaluation of graft integrity and screw breakdown, and completion of the pain and symptom items of the KOOS (Knee injury and Osteoarthritis Outcome Score) questionnaire. Results: At a mean of three years (range, 2.5 to 4.0 years) after surgery, thirty-one patients with sixty-two CALAXO screws and thirty-six patients with seventy-two MILAGRO screws returned for repeat evaluation. Two blinded, independent reviewers found no significant differences between the two screw types when comparing radiographs for tibial or femoral tunnel widening or MRIs for graft integrity, tibial and femoral foreign body reactions, or femoral screw degradation. Both reviewers found a significant difference between the two screw types when comparing tibial screw degradation properties (p MILAGRO screws were more likely to be rated as intact. No significant differences were noted between the two screw types when comparing the two KOOS subscales. Conclusions: CALAXO screws in the tibial tunnel were more likely to be rated as degraded or partially degraded compared with MILAGRO screws at a mean

  15. 关节镜下RetroButton-同种异体肌腱-界面螺钉重建前交叉韧带的近期疗效%SHORT-TERM EFFECTIVENESS OF ARTHROSCOPIC ANTERIOR CRUCIATE LIGAMENT RECONSTRUCTION WITH RetroButton-ALLOGENEIC TENDON-INTERFERENCE SCREW

    Institute of Scientific and Technical Information of China (English)

    陈竞青; 陈百成; 高石军; 李彤; 邵德成

    2011-01-01

    目的 探讨关节镜下应用RetroButton-同种异体肌腱-界面螺钉重建前交叉韧带的手术方法与近期疗效.方法 2009年6月-10月,于关节镜下采用RetroButton-同种异体肌腱-界面螺钉重建23例前交叉韧带损伤.男15例,女8例;年龄19~46岁,平均32.5岁.左膝17例,右膝6例.致伤原因:运动伤13例,交通事故伤8例,坠落伤2例.急性损伤(6周)16例.合并单纯内侧半月板损伤11例,单纯外侧半月板损伤6例,内、外侧半月板同时损伤3例,关节软骨损伤5例.患者均无后交叉韧带、内外侧副韧带或后外侧结构损伤.受伤至手术时间3周~32个月.按照Lysholm评分和国际膝关节评分委员会(IKDC)膝关节评分标准进行主观评估;采用Lachman 试验和KT-1000关节测量仪检查进行客观评估.结果 术后患者切口均Ⅰ期愈合,患膝关节失稳症状明显改善.无高热、感染或明显排斥反应.1例患者术后发生顽固性滑膜炎,关节内反复积液,3周内经关节腔灌洗7次后稳定.患者均获随访,随访时间10~17个月,平均14.7个月.末次随访时IKDC评分、Lyrsholm评分、Lachman试验及KT-1000检测与术前比较,差异均有统计学意义(P<0.05).结论 关节镜下应用RetroButton-同种异体肌腱-界面螺钉重建前交叉韧带手术操作安全、简便,近期疗效满意.%Objective To investigate the method and short-term effectiveness of arthroscopic reconstruction of anterior cruciate ligament (ACL) using RetroButton-allogeneic tendon-interference screw. Methods Between June 2009 and October 2009, 23 patients with ACL rupture were treated by arthroscopic reconstruction with RetroButton-allogeneic tendon-interference screw. There were 15 males and 8 females with an average age of 32.5 years (range, 19-46 years), including 17 left knees and 6 right knees. The injury causes were sport trauma (13 cases), traffic accident (8 cases), and falling injury (2 cases). There were 7 acute cases (< 6 weeks

  16. 微螺钉结合片段弓技术内收上前牙的临床研究%Micro-screw with Segmental Arch Technique for En-masse Retraction of Maxillary Anterior Teeth:A Clinical Cephalometric Study

    Institute of Scientific and Technical Information of China (English)

    张燕琴; 林新平

    2013-01-01

    目的:评估微螺钉结合片段弓技术内收上前牙对上切牙垂直向和转矩控制的效果.方法:选取16例上颌前突患者分为实验组(微螺钉结合片段弓技术)和对照组(微螺钉全牙弓).测量治疗前后的X线头颅定位侧位片相关指标,使用SPSS17.0软件分析.结果:实验组上切牙切缘至RL(通过翼上颌裂点作腭平面的垂线)距离U1E-RL减小7.26 mm,阻抗中心至RL距离U1CR-RL减小3.72 mm,根尖至RL距离U1AP-RL减小1.23 mm,切缘至腭平面的距离U1E-PP增加0.49 mm,阻抗中心至腭平面的距离U1CR-PP减小0.19 mm,根尖至腭平面的距离U1AP-PP减小0.25 mm,上切牙长轴与腭平面交角U1-PP减小11.65°;对照组U1E-RL减小6.18mm,U1CR-RL减小2.94 mm,减小U1AP-RL 0.47 mm,U1E-PP增加0.53 mm,U1CR-PP增加0.27 mm,U1 AP-PP增加0.28 mm,U1-PP减小16.31°.结论:微螺钉结合片段弓技术内收上前牙对上切牙的转矩和垂直向控制较好.%Objective:To evaluate the efficiency of micro-screw with segmental arch technique for en-masse retraction of maxillary anterior teeth.Methods:Sixteen subjects with upper dental alveolar bone protrusion were selected for this study.They were divided into two groups:experimental group (micros-crew with sectional arch technique) and control group (micro-screw with the whole arch).Torque and vertical of the central incisor were evaluated cephalometrically before and after orthodontic retraction.All data were analyzed by SPSS17.0 software.Results:Experimental group:U1E-RL was decreased by 7.26mm,U1CR-RL was decreased by 3.72mm,U1AP -RL was decreased by 1.23mm,U1E-PP was increased by 0.49mm,U1CR-PP was decreased by 0.19mm,U1AP-PP was decreased by 0.25mm,U1-PP was decreased by 11.65°; control group:U1E-RL was decreased by 6.18mm,U1CR-RL was decreased by 2.94mm,U1AP-RL was decreased by 0.47mm,U1E-PP was increased by 0.53mm,U1CR-PP was increased by 0.27mm,U1AP-PP was increased by 0.28mm,U1-PP was decreased by 16.31°.Conclusion:Micro-screw

  17. Self-energized screw coupling

    Science.gov (United States)

    Lefever, A. E.; Totah, R. S.

    1980-01-01

    Threaded coupling carries its own store of rotational energy. Originally developed to ease task of astronauts assembling structures in space, coupling offers same advantages in other hazardous operations, such as underwater and in and around nuclear reactors. Coupling consists of two parts: crew portion and receptacle. When screw portion is inserted into receptacle and given slight push by operator, trigger pins release ratchet, allowing energy stored in springs to rotate screw into nut in receptacle.

  18. Biomechanical properties of a novel biodegradable magnesium-based interference screw

    Directory of Open Access Journals (Sweden)

    Marco Ezechieli

    2016-06-01

    Full Text Available Magnesium-based interference screws may be an alternative in anterior/posterior cruciate ligament reconstruction. The well-known osteoconductive effects of biodegradable magnesium alloys may be useful. It was the purpose of this study to evaluate the biomechanical properties of a magnesium based interference screw and compare it to a standard implant. A MgYREZr-alloy interference screw and a standard implant (Milagro®; De Puy Mitek, Raynham, MA, USA were used for graft fixation. Specimens were placed into a tensile loading fixation of a servohydraulic testing machine. Biomechanical analysis included pretensioning of the constructs at 20 N for 1 min following cyclic pretensioning of 20 cycles between 20 and 60 N. Biomechanical elongation was evaluated with cyclic loading of 1000 cycles between 50 and 200 N at 0.5 Hz. Maximum load to failure was 511.3±66.5 N for the Milagro® screw and 529.0±63.3 N for magnesium-based screw (ns, P=0.57. Elongations after preload, during cyclical loading and during failure load were not different between the groups (ns, P>0.05. Stiffness was 121.1±13.8 N/mm for the magnesiumbased screw and 144.1±18.4 for the Milagro® screw (ns, P=0.32. MgYREZr alloy interference screws show comparable results in biomechanical testing to standard implants and may be an alternative for anterior cruciate reconstruction in the future.

  19. Direct Transpedicular Osteosynthesis with Lag Screw in the Treatment of Hangman's Fracture%颈椎弓根拉力螺钉治疗Hangman骨折

    Institute of Scientific and Technical Information of China (English)

    周栋; 谭军; 蔡晓冰; 袁文; 贾连顺

    2003-01-01

    目的探讨经C2椎弓拉力螺钉治疗Hangman骨折的临床应用价值.方法 9例C2椎弓骨折患者行C2椎弓拉力螺钉内固定术.结果术后随访3~11个月,颈椎侧位X线片检查,9例患者均获骨性愈合,达到了预期的临床效果.结论经C2椎弓拉力螺钉治疗Hangman骨折临床疗效满意.

  20. Lumbar Spinal Stenosis Minimally Invasive Treatment with Bilateral Transpedicular Facet Augmentation System

    Energy Technology Data Exchange (ETDEWEB)

    Masala, Salvatore, E-mail: salva.masala@tiscali.it [Interventional Radiology and Radiotherapy, University of Rome ' Tor Vergata' , Department of Diagnostic and Molecular Imaging (Italy); Tarantino, Umberto [University of Rome ' Tor Vergata' , Department of Orthopaedics and Traumatology (Italy); Nano, Giovanni, E-mail: gionano@gmail.com [Interventional Radiology and Radiotherapy, University of Rome ' Tor Vergata' , Department of Diagnostic and Molecular Imaging (Italy); Iundusi, Riccardo [University of Rome ' Tor Vergata' , Department of Orthopaedics and Traumatology (Italy); Fiori, Roberto, E-mail: fiori.r@libero.it; Da Ros, Valerio, E-mail: valeriodaros@hotmail.com; Simonetti, Giovanni [Interventional Radiology and Radiotherapy, University of Rome ' Tor Vergata' , Department of Diagnostic and Molecular Imaging (Italy)

    2013-06-15

    Purpose. The purpose of this study was to evaluate the effectiveness of a new pedicle screw-based posterior dynamic stabilization device PDS Percudyn System Trade-Mark-Sign Anchor and Stabilizer (Interventional Spine Inc., Irvine, CA) as alternative minimally invasive treatment for patients with lumbar spine stenosis. Methods. Twenty-four consecutive patients (8 women, 16 men; mean age 61.8 yr) with lumbar spinal stenosis underwent implantation of the minimally invasive pedicle screw-based device for posterior dynamic stabilization. Inclusion criteria were lumbar stenosis without signs of instability, resistant to conservative treatment, and eligible to traditional surgical posterior decompression. Results. Twenty patients (83 %) progressively improved during the 1-year follow-up. Four (17 %) patients did not show any improvement and opted for surgical posterior decompression. For both responder and nonresponder patients, no device-related complications were reported. Conclusions. Minimally invasive PDS Percudyn System Trade-Mark-Sign has effectively improved the clinical setting of 83 % of highly selected patients treated, delaying the need for traditional surgical therapy.

  1. 创伤性颈椎不稳后路钉棒固定重建稳定%Stability reconstruction of traumatic cervical vertebra by screw-rod fixation through posterior approach

    Institute of Scientific and Technical Information of China (English)

    周章彦; 朱轶; 谢彬; 林义文

    2012-01-01

    Objective To explore the therapeutic effect on treatment of traumatic instability of cervical vertebra by pedicel screw through posterior approach or screw-rod fixation in lateral mass. Methods 30 patients of traumatic cervical vertebra instability were treated with grafting in cervical spinal lamina or between small joints by posterior transpedicular screw through posterior approach or screw-rod fixation in lateral mass. Results All cervical symptoms disappeared after operation and the damaged neurological function of cervical spinal cord were significantly improved. No complication was found in the follow up visits for 3 ~ 52 ( 10 ± 3. 2 ) months. The recovered cervical vertebra of all patients was of well fused and stable without looseness, fracture of interior fixation or displacement of grafting bone; the fracture was well healing and grafting bone was gradually fused with flexion range of extensible i05°±i0.5°, lateral 80° ±7. 2°, and axial rotation 96° ±9. 3°. Conclusions The treatment of the traumatic cervical vertebra by posterior transpedicular screw through posterior approach or screw-rod fixation in lateral mass reveals good reconstructed stability.%目的 探讨颈后路椎弓根钉或侧块螺钉-棒内固定治疗颈椎创伤性不稳临床效果.方法 对30例创伤性颈椎不稳患者行后路椎弓根钉或侧块螺钉-棒内固定,椎板或小关节间植骨.结果 术后颈部症状完全消失,受损颈髓神经功能明显改善.30例均获随访,时间3~52(10±3.2)个月,未发生并发症.颈椎复位良好,序列稳定;无内固定松动、断裂、植骨块移位;骨折愈合好,植骨渐进融合.颈椎伸屈角度105°±10.5°,侧屈角度80°±7.2°,轴向旋转功能96°±9.3°.结论 颈椎创伤性不稳采用经后路椎弓根钉或侧块螺钉-棒内固定治疗能够达到良好的稳定效果.

  2. Percutaneous Cement-Augmented Screws Fixation in the Fractures of the Aging Spine: Is It the Solution?

    Directory of Open Access Journals (Sweden)

    Sébastien Pesenti

    2014-01-01

    Full Text Available Introduction. Management of elderly patients with thoracolumbar fractures is still challenging due to frequent osteoporosis and risk of screws pull-out. The aim of this study was to evaluate results of a percutaneous-only procedure to treat these fragile patients using cement-augmented screws. Methods. 12 patients diagnosed with a thoracolumbar fracture associated with an important loss of bone stock were included in this prospective study. Surgical procedure included systematically a percutaneous osteosynthesis using cemented fenestrated screws. When necessary, additional anterior support was performed using a kyphoplasty procedure. Clinical and radiographic evaluations were performed using CT scan. Results. On the whole series, 15 fractures were diagnosed and 96 cemented screws were inserted. The difference between the pre- and postoperative vertebral kyphosis was statistically significant (12.9° versus 4.4°, P=0.0006. No extrapedicular screw was reported and one patient was diagnosed with a cement-related pulmonary embolism. During follow-up period, no infectious complications, implant failures, or pull-out screws were noticed. Discussion. Aging spine is becoming an increasing public health issue. Management of these patients requires specific attention due to the augmented risk of complications. Using percutaneous-only screws fixation with cemented screw provides satisfactory results. A rigorous technique is mandatory in order to achieve best outcomes.

  3. Biomechanical evaluation of Caspar cervical screws: comparative stability under cyclical loading.

    Science.gov (United States)

    Gallagher, M R; Maiman, D J; Reinartz, J; Pintar, F; Yoganandan, N

    1993-12-01

    Anterior cervical instrumentation is used as an adjunct to bone fusion; however, definitive biomechanical data to support some applications and techniques are lacking. In the absence of supportive experimental data, posterior cortical penetration has been recommended with the Caspar system. Previously, we compared the axial pull-out strength of Caspar screws with and without posterior cortical penetration. This study compares the stability of unicortical versus bicortical screw penetration groups under cyclical loading simulating physiological flexion-extension. Caspar screws were placed in human cadaveric vertebrae with or without posterior cortical purchase. Each screw was separately tested, simulating flexion-extension to 200 cycles. Deformation time data allowed a direct comparison of screw "wobble" with and without posterior cortical purchase. The mean deformation differences between subcortical and bicortical groups were statistically significant and increased over time within both groups. Enhanced stability was noted with bicortical purchase throughout most of the examined range, becoming more pronounced over longer periods of cyclical loading. Significant (P < 0.05) increases in deformation over time were noted for both groups, suggesting potentially significant deterioration at the screw-bone interface, despite bicortical purchase. Such deterioration with repeated flexion-extension loading may be of concern in the use of Caspar plates in the presence of multicolumn instability.

  4. Management of anterior dental crossbite with removable appliances

    Directory of Open Access Journals (Sweden)

    Ayca Tuba Ulusoy

    2013-01-01

    Full Text Available This case report describes the treatment of an 8-year-old girl with anterior dental crossbite using a series of removable appliances to bring the teeth into a normal position. Clinical presentation and intervention: A removable acrylic appliance with a bite plate incorporating a screw was used to correct the anterior dental crossbite and align the incisors. The subsequent eruption of the maxillary left lateral incisor on the palatinal side was treated with a second acrylic plate incorporating a labiolingual spring. After an 8-month period, the anterior crossbite involving multiple incisors was corrected.

  5. Posterior fixation and fusion with atlas pedicle screw system for upper cervical diseases

    Institute of Scientific and Technical Information of China (English)

    LI Lei; ZHOU Feng-hua; WANG Huan; CUI Shao-qian

    2008-01-01

    Objective: To evaluate the feasibility, safety and efficacy of atlas pedicle screws system fixation and fusion for the treatment of upper cervical diseases. Methods: Twenty-three consecutive patients with up-per cervical disorders requiring stabilization, including 19 cases of atlantoaxial dislocation (4 congenital odontoid disconnections, 6 old odontoid fractures, 4 fresh odontoid fractures of Aderson Ⅱ C, 3 ruptures of the C1 transverse ligament, and 2 fractures ofC1), 2 cases ofC2 tumor (instability after the resection of the tumors), and 2 giant neurilemomas of C2-C3(instability after resection of the tumors), were treated by posterior fixation and fusion with the atlas pedicle screw system, in which the screws were inserted through the posterior arch of Cr The operative time, bleeding volume and complications were reported. All patients were immobilized without external fixation or with rigid cervical collars for 1-3 months. All patients were followed up and evaluated with radiographs and CT. Results: In the 23 patients, 46 C1 pedicle screws, 42 C2 pedicle screws and 6 lower cervical lateral mass screws and 2 lower cervical pedicle screws were placed. The mean operative time and bleeding volume was 2.7 hours and 490 ml respectively. No intraoperative complications were directly related to surgical technique. No neurological, vascular or infective complications were encountered. All patients were followed up for 3-36 months (average 15 months). Firm bony fusion was documented in all patients after 3-6 months. One patient with atlas fracture showed anterior occipitocervical fusion. There was no implant failure. Conclusions: Posterior fixation and fusion of the atlas pedicle screw system is feasible and safe for the treatment of upper cervical diseases, and may be applicable to a larger number of patients.

  6. Cancellous Screws Are Biomechanically Superior to Cortical Screws in Metaphyseal Bone.

    Science.gov (United States)

    Wang, Tim; Boone, Christopher; Behn, Anthony W; Ledesma, Justin B; Bishop, Julius A

    2016-09-01

    Cancellous screws are designed to optimize fixation in metaphyseal bone environments; however, certain clinical situations may require the substitution of cortical screws for use in cancellous bone, such as anatomic constraints, fragment size, or available instrumentation. This study compares the biomechanical properties of commercially available cortical and cancellous screw designs in a synthetic model representing various bone densities. Commercially available, fully threaded, 4.0-mm outer-diameter cortical and cancellous screws were tested in terms of pullout strength and maximum insertion torque in standard-density and osteoporotic cancellous bone models. Pullout strength and maximum insertion torque were both found to be greater for cancellous screws than cortical screws in all synthetic densities tested. The magnitude of difference in pullout strength between cortical and cancellous screws increased with decreasing synthetic bone density. Screw displacement prior to failure and total energy absorbed during pullout strength testing were also significantly greater for cancellous screws in osteoporotic models. Stiffness was greater for cancellous screws in standard and osteoporotic models. Cancellous screws have biomechanical advantages over cortical screws when used in metaphyseal bone, implying the ability to both achieve greater compression and resist displacement at the screw-plate interface. Surgeons should preferentially use cancellous over cortical screws in metaphyseal environments where cortical bone is insufficient for fixation. [Orthopedics.2016; 39(5):e828-e832.].

  7. Treatment of lumbar spondylolisthesis with viaposterior transpedicular instrumentation and intervertebral fusion%椎弓根螺钉复位固定加椎体间植骨融合治疗腰椎滑脱症

    Institute of Scientific and Technical Information of China (English)

    李敬朝

    2010-01-01

    目的 评价经后路椎弓根螺钉内固定并腰椎椎体间植骨融合术治疗腰椎滑脱的临床疗效.方法 对65例腰椎滑脱症患者行后路椎板减压,应用后路椎弓根螺钉内固定系统对腰椎滑脱椎体进行复位固定,椎体间或后外侧植骨融合.结果 随访6~24个月,临床优良率90.8%,6~12个月复查X线片均显示椎体间骨性融合.结论 本组采用椎管减压,椎体复位,椎弓根螺钉内固定并椎体间植骨融合治疗腰椎滑脱症,具有复位率、融合率高,疗效确切的特点,是治疗腰椎滑脱症比较理想的手术方式.%Objective To evaluate the clinical effect of treating lumbar spondylolisthesis with viaposterior transpedicular instrumentation and intervertebral fusion. Methods The posterior decompression and surgical treatment of transpedicle screw fixation system were used in 65 patients with lumbar spondylolisthesis, to fix spondylolis lumbar vertebrae and obtain vertebra fusion and posterolateral bone grafting fusion. Results The follow-up period ranged from 6 to 24 months. The clinical excellent rate was 92%. The interspinal solid fusion was observed in all patients in X-ray between 6 to 12 month s after operation. Conclusions This unit applies vertebrallamina decompression, vertebral body reposition, posterior transpadicular instrumentation and autoiliacbone intervertebral bone grafting to treat lumbar spondylolisthesis which shows a high rate of reposition, high fusion rate, definite curative effect and reduces the complication rate after lumbar operation. It is a good way of surgery.

  8. MODIFIED PERIODONTAL EXPLORER FOR EXPANSION SCREW ACTIVATION

    Directory of Open Access Journals (Sweden)

    Srinivasan

    2012-08-01

    Full Text Available INTRODUCTION: Accidents with expansion screw activation keys are r eported in the literature 1,2 . A simple method to prevent such accident is to use a modified periodontal explorer as a key for expansion screw activation. A no.17 per iodontal explorer (fig 1 is cut at its first terminal bend (fig 2. The second section is bent m ore vertically to the long axis of the shaft (fig 3. This part which is tapered and stiff enough to ac tivate the screw is tried extra orally into the screw. It is further trimmed in such a way that onl y a mm of instrument can project through the screw hole (fig 4. Now a safe key for activating t he maxillary expansion screw is ready to use (fig 5. Once the patient’s parent or guardian succes sfully repeat the activation procedure in office, the instrument can be given to them for hom e use

  9. Shock-Absorbent Ball-Screw Mechanism

    Science.gov (United States)

    Hirr, Otto A., Jr.; Meneely, R. W.

    1986-01-01

    Actuator containing two ball screws in series employs Belleville springs to reduce impact loads, thereby increasing life expectancy. New application of springs increases reliability of equipment in which ball screws commonly used. Set of three springs within lower screw of ball-screw mechanism absorbs impacts that result when parts reach their upper and lower limits of movement. Mechanism designed with Belleville springs as shock-absorbing elements because springs have good energy-to-volume ratio and easily stacked to attain any stiffness and travel.

  10. Comparison of interfaces of different pedicle screws with micro-CT technique in lumbar vertebrae with osteoporosis of sheep

    Directory of Open Access Journals (Sweden)

    Da LIU

    2015-07-01

    Full Text Available Objective To compare the changes in interfaces of expandable pedicle screw (EPS and polymethylmethacrylateenhanced pedicle screw (PMMA-PS after being used in osteoporotic sheep lumbar vertebrae with micro-CT technique. Methods Six lumbar vertebrae (L1-L6 in each sheep were randomly divided into three different screw-insertion groups (two vertebrae with four pedicles in each group after reproduction of osteoporosis in sheep. After making the pilot hole using the same method, CPS was inserted through the pilot hole into vertebral body in CPS group, while PMMA (1.0ml was injected into the pilot hole prior to the insertion of CPS in PMMA-PS group, and EPS was inserted through pedicle into vertebral body in EPS group. All the sheep were sacrificed, and lumbar vertebrae (L1-L6 were harvested respectively at the 6- and 12-week postoperatively. The micro-CT three dimensional reconstruction and histomorphometric analysis were performed to evaluate the interfacial conditions. Results  It was clearly demonstrated that interface was formed where the bone trabeculae was directly in contact with the screw to form "screw-bone" interface in both CPS and EPS groups both 6 weeks and 12 weeks after the operation. The screw was fully surrounded by PMMA and formed "screw-PMMA-bone" interface in PMMA-PS group. The anterior part of EPS expanded in vertebral body to form a clawlike structure, pressing against the surrounding bone trabeculae, thus significantly improved the local bone quality (amount and density of bone trabeculae. From 6 weeks to 12 weeks after the operation, there was no visual difference in bone quality around the screw in both CPS and PMMA-PS groups. There was no degradation and absorption of PMMA, and it led to form the second non-biological interface in PMMA-PS group. Nevertheless, bone quality around expanding part of EPS at 12-week post-operation was significantly improved compared with that at 6-week post-operation, thus forming a good

  11. An implant-supported, screw-retained, provisional fixed partial denture for pontic site enhancement.

    Science.gov (United States)

    Mitrani, Ricardo; Phillips, Keith; Kois, John C

    2005-01-01

    Due to remodeling of the edentulous ridge following tooth extraction, clinicians and dental technicians face a variety of challenges when attempting to deliver an aesthetic fixed partial denture for the anterior maxilla. An implant-supported, screw-retained fixed partial denture provisional restoration can be utilized in order to manipulate the pontic site with predictable success. This technique can create the illusion of pontics emerging from the soft tissue, creating a natural-looking effect for seating of the definitive restoration.

  12. Anterior cervical fusion and Caspar plate stabilization for cervical trauma.

    Science.gov (United States)

    Caspar, W; Barbier, D D; Klara, P M

    1989-10-01

    A technique for anterior cervical iliac graft fusion with standardized, commercially available screw and plate fixation (Caspar plating) has been developed. The step-by-step procedure, as well as the instruments designed to facilitate the procedure, are described in this report. Sixty cases of cervical trauma (fractures, subluxations, ligamentous instability, or a combination of these problems) were treated with Caspar plating. All patients obtained fusion, and stability was achieved immediately after surgery without external stabilization. No unusual surgical complications occurred, and the most dreaded complication of dural penetration by drilling or screw placement was not observed. This report details the neurological presentation, anatomical lesions, surgical therapy, and outcome of these patients. Caspar plating combines the advantage of an anterior surgical approach with immediate postoperative stabilization without external stabilization. This advantage persists even in the presence of posterior ligamentous instability. The technique is an important addition to the surgical treatment of cervical trauma.

  13. Anatomic comparison of transarticular screws with lateral mass screws in cervical vertebrae

    Institute of Scientific and Technical Information of China (English)

    LIU Guan-yi; XU Rong-ming; MA Wei-hu; RUAN Yong-ping; SUN Shao-hua; HUANG Lei

    2007-01-01

    Objective: To compare the potential incidence of nerve root (ventral and dorsal ramus) injury caused by cervical transarticular screws and Roy-Camille lateral mass screws.Methods: Insertion techniques with Klekamp transarticular screws and Roy-Camille lateral mass screws were respectively performed in this study. Each technique involved four specimens and 40 screws, which were inserted from C3 to C7. And 20-mm-long screws were used to overpenetrate the ventral cortex. The anterolateral aspect of the cervical spine was carefully dissected to allow observation of the screw-ramus relationship.Results: The overall percentage of nerve invasion was significantly lower with Klekamp (45%) technique than with Roy-Camille (85%) technique (P<0.05). The largest percentage of nerve invasion for Klekamp transarticular screws was found at the dorsal ramus (25%), followed by the ventral ramus (15%) and the bifurcation of the ventral dorsal ramus (5%). The largest percentage of nerve invasion for Roy-Camille lateral mass screws was found at the ventral ramus (80%).Conclusion: The potential risk of nerve root invasion is lower with Klekamp transarticular screws than with Roy-Camille lateral mass screws.

  14. Twin-Screw Extruders in Ceramic Extrusion

    Science.gov (United States)

    Wiedmann, Werner; Hölzel, Maria

    The machines mainly used for compounding plastics, chemicals and food are co-rotating, closely intermeshing twin-screw extruders. Some 30 000 such extruders are in use worldwide, about 1/3 are ZSKs from Coperion Werner & Pfleiderer, Stuttgart. In the chemical industry more and more batch mixers are being replaced by continuous twin-screw kneaders.

  15. Twin screw granulation: steps in granule growth.

    Science.gov (United States)

    Dhenge, Ranjit M; Cartwright, James J; Hounslow, Michael J; Salman, Agba D

    2012-11-15

    The present work focuses on the study of the progression of granules in different compartments along the length of screws in a twin screw granulator (TSG). The effects of varying powder feed rate; liquid to solid ratio and viscosity of granulation liquid on properties of granules was studied. The bigger granules produced at the start of the process were found to change in terms of size, shape and strength along the screw length at all the conditions investigated. The granules became more spherical and their strength increased along the screw length. Tracer granules were also introduced in order to understand the role of kneading and conveying elements in the TSG. The kneading elements promoted consolidation and breakage while the conveying elements led to coalescence, breakage and some consolidation. The results presented here help to provide a qualitative and quantitative understanding of the twin screw granulation process.

  16. Simple Technique for Removing Broken Pedicular Screws

    Directory of Open Access Journals (Sweden)

    A Agrawal

    2014-03-01

    Full Text Available The procedure for removing a broken pedicle screw should ideally be technically easy and minimally invasive, as any damage to the pedicle, during removal of the broken screw, may weaken the pedicle, thus compromising on the success of re-instrumentation. We describe the case of a 32-year old man who had undergone surgery for traumatic third lumbar vertebral body fracture three years prior to current admission and had developed the complication of pedicle screw breakage within the vertebral body. The patient underwent re-exploration and removal of the distal screws. Through a paravertebral incision and muscle separation, the screws and rods were exposed and the implants were removed.

  17. Twin screw subsurface and surface multiphase pumps

    Energy Technology Data Exchange (ETDEWEB)

    Dass, P. [CAN-K GROUP OF COMPANIES, Edmonton, Alberta (Canada)

    2011-07-01

    A new subsurface twin screw multiphase pump has been developed to replace ESP and other artificial lift technologies. This technology has been under development for a few years, has been field tested and is now going for commercial applications. The subsurface twin screw technology consists of a pair of screws that do not touch and can be run with a top drive or submersible motor; and it carries a lot of benefits. This technology is easy to install and its low slippage makes it highly efficient with heavy oil. In addition twin screw multiphase pumps are capable of handling high viscosity fluids and thus their utilization can save water when used in thermal applications. It also induces savings of chemicals because asphaltenes do not break down easily as well as a reduction in SOR. The subsurface twin screw multiphase pump presented herein is an advanced technology which could be used in thermal applications.

  18. Anterior cruciate ligament femoral socket drilling with a retrograde reamer: lessons from the learning curve.

    Science.gov (United States)

    Ferraz, Victor; Westerberg, Paul; Brand, Jefferson C

    2013-01-01

    Whereas "anatomic" anterior cruciate ligament reconstruction may improve clinical results, the technique has introduced new technical challenges. The purpose of this technical note and video is to explore tips and tricks that improve femoral socket drilling with a retrograde reamer, bone-patellar tendon-bone graft passage, and interference screw fixation. The techniques for retrograde femoral socket drilling in an inside-out direction, bone-patellar tendon-bone graft passage, and interference screw fixation are described and demonstrated. Pitfalls, troubleshooting tips, and possible solutions are discussed. With the retrograde reamer, the femoral socket can be placed in the footprint of the anterior cruciate ligament with a longer and more vertical tunnel. By modifying the size of the patellar bone plug, graft passage is improved. With care and technique, interference screw fixation in the femoral socket over a guidewire is possible.

  19. Pedicle screw placement in the lumbar spine: effect of trajectory and screw design on acute biomechanical purchase.

    Science.gov (United States)

    Wray, Steven; Mimran, Ronnie; Vadapalli, Sasidhar; Shetye, Snehal S; McGilvray, Kirk C; Puttlitz, Christian M

    2015-05-01

    OBJECT Low bone mineral density in patients undergoing lumbar spinal surgery with screws is an especially difficult challenge because poor bone quality can severely compromise the maximum achievable purchase of the screws. A relatively new technique, the cortical bone screw trajectory, utilizes a medialized trajectory in the caudocephalad direction to engage a greater amount of cortical bone within the pars interarticularis and pedicle. The objectives of this cadaveric biomechanical study were to 1) evaluate a cortical screw system and compare its mechanical performance to the traditional pedicle screw system; 2) determine differences in bone quality associated with the cortical screw trajectory versus the normal pedicle screw insertion technique; 3) determine the cortical wall breach rate with both the cortical and traditional screw trajectories; and 4) determine the performance of the traditional screw in the cortical screw trajectory. METHODS Fourteen fresh frozen human lumbar spine sections (L1-5) were used in this study (mean age 57 ± 19 years). The experimental plan involved drilling and tapping screw holes for 2 trajectories under navigation (a traditional pedicle screw and a cortical screw) in both high-and low-quality vertebrae, measuring the bone quality associated with these trajectories, placing screws in the trajectories, and evaluating the competence of the screw purchase via 2 mechanical tests (pullout and toggle). The 3 experimental variants were 1) traditional pedicle screws placed in the traditional pedicle screw trajectory, 2) traditional pedicle screws placed in the cortical screw trajectory, and 3) cortical screws placed in the cortical screw trajectory. RESULTS A statistically significant increase in bone quality was observed for the cortical trajectories with a cortical screw (42%; p parameter comparisons (screw type and trajectory) between high-quality and lowquality samples were significant (p parameters determined from pullout and toggle

  20. Design of digitized anterior approach screw fixation program:Clinical application in the treatment of type Ⅱ odontoid fractures%数字化颈前路螺钉内固定方案设计:Ⅱ型齿状突骨折的临床应用

    Institute of Scientific and Technical Information of China (English)

    陈宣煌; 张国栋; 吴长福; 林海滨

    2013-01-01

      BACKGROUND: The treatment of type Ⅱ odontoid fractures has the difficulties of difficult, high risk and the choice between cervical spine stability and cervical activity. OBJECTIVE: To investigate the method and clinical application of computer in the three-dimensional construction of type Ⅱ odontoid fractures, reduction and design of digitized fixation. METHODS: One cervical specimen was used to prepare the type Ⅱ odontoid fractures model for high-speed thin CT scan. The model was reconstructed and reseted in the Mimics. The Solidworks was used to design the screw and performed virtual simulation on the three-dimensional model of fracture reduction in order to guide the clinical application. RESULTS AND CONCLUSION: Three-dimensional reconstruction and reduction were performed on the fracture model, and the virtual screw fixation was completed according to the three-dimensional measurement data thus guiding the clinical surgery successful y. The results show that digitized screw fixation that used in the treatment of type Ⅱ odontoid fractures can be designed on the computer with Mimics and Solidworks, which has good reference value to the clinical surgery.%  背景:Ⅱ型齿状突骨折的治疗存在难度大、风险高以及颈椎稳定性和颈椎活动度之间的选择难点。目的:探讨计算机软件应用于Ⅱ型齿状突骨折三维重建、复位以及数字化内固定设计的方法和临床应用。方法:将1具颈椎标本制作成Ⅱ型齿状突骨折类型,进行高速CT薄层扫描,在Mimics中对骨折模型进行重建、复位,以 Solidworks 进行螺钉的设计,并在骨折复位三维模型上进行虚拟内固定,以此指导临床。结果与结论:对骨折标本模型进行了三维重建、复位,根据三维模型测量数据,完成虚拟螺钉内固定,并成功指导临床手术。结果显示,应用Mimics及Solidworks可在计算机上设计出用于治疗Ⅱ型齿状突骨折的数

  1. An alternative clinical approach to achieve greater anterior than posterior maxillary expansion in cleft lip and palate patients.

    Science.gov (United States)

    Oliveira, Dauro Douglas; Bartolomeo, Flávia Uchôa Costa; Cardinal, Lucas; Figueiredo, Daniel Santos Fonseca; Palomo, Juan Martin; Andrade, Ildeu

    2014-11-01

    Cleft lip and palate patients commonly present maxillary constriction, particularly in the anterior region. The aim of this case report was to describe an alternative clinical approach that used a smaller Hyrax screw unconventionally positioned to achieve greater anterior than posterior expansion in patients with complete unilateral cleft lip and palate. The idea presented here is to take advantage of a reduced dimension screw to position it anteriorly. When only anterior expansion was needed (patient 1), the appliance was soldered to the first premolar bands and associated to a transpalatal arch cemented to the first molars. However, when overall expansion was required (patient 2), the screw was positioned anteriorly, but soldered to the first molar bands. Intercanine, premolar, and first molar widths were measured on dental casts with a digital caliper. Pre-expansion and postexpansion radiographs and tomographies were also evaluated. A significant anterior expansion and no intermolar width increase were registered in the first patient. Although patient 2 also presented a greater anterior than posterior expansion, a noteworthy expansion occurred at the molar region. The alternative approach to expand the maxilla in cleft patients reported here caused greater anterior than posterior expansion when the Mini-Hyrax was associated to a transpalatal arch, and its reduced dimension also minimized discomfort and facilitated hygiene.

  2. A geometrical introduction to screw theory

    Science.gov (United States)

    Minguzzi, E.

    2013-05-01

    This work introduces screw theory, a venerable but little known theory aimed at describing rigid body dynamics. This formulation of mechanics unifies in the concept of screw the translational and rotational degrees of freedom of the body. It captures a remarkable mathematical analogy between mechanical momenta and linear velocities, and between forces and angular velocities. For instance, it clarifies that angular velocities should be treated as applied vectors and that, under the composition of motions, they sum with the same rules of applied forces. This work provides a short and rigorous introduction to screw theory intended for an undergraduate and general readership.

  3. Ergotropic effect of bone cement on pedicle screw fixation in treatment of osteoporotic thoracolumbar fracture

    Directory of Open Access Journals (Sweden)

    Da LIU

    2017-02-01

    Full Text Available Objective To evaluate the ergotropic effect of bone cement on pedicle screw fixation in treatment of osteopo¬rotic thoracolumbar fracture. Methods Fifty-three patients with osteoporotic thoracolumbar fracture, admitted from Jun. 2013 to Dec. 2014, were included for treatment by augmentation of pedicle screw fixation with bone cement. All patients underwent pre-operative examination of bone mineral density with T-score ≤-2.5 and augmentation of pedicle screw fixation with injection of 1.5 ml bone cement in adjacent to fractured vertebra. All patients were treated with anti-osteoporosis therapy pre- and post-operation, ob¬served and recorded with basic conditions and complications. At pre-operation, one-week post-operation and last follow-up, pain vi¬sual analogue scale (VAS and neurological function score (ASIA of all patients were recorded, and the compression rats of anterior and posterior edge of fractured vertebra, and compression rats of spinal canal and Cobb angel of all patients were measured. Results All the 53 patients were successfully undergone operation in about 90-140 min with blood loss of about 150-350 ml. No spinal cord or nerve injury, dural tear and obvious leakage of bone cement and screw loosening occurred during operation. All patients were followed up for 12 to 36 months and the neurological function obviously recovered contrasted with pre-operation. X-ray and CT examination at last follow-up showed good fractures healing, good position and non-loosening of internal fixation device and non-leakage of bone cement. At one week post-operation and last follow-up, VAS, compression rats of anterior edge and posterior edge of fractured vertebra, compression rats of spinal canal and Cobb angel were significantly lower than those at pre-operation (P0.05. Conclusions Augmentation of pedicle screw fixation with bone cement can effectively strengthen the initial stability of pedicle screw in osteo¬porosis, restore the

  4. A Biomechanical Comparison of Expansive Pedicle Screws for Severe Osteoporosis: The Effects of Screw Design and Cement Augmentation.

    Directory of Open Access Journals (Sweden)

    Ching-Lung Tai

    Full Text Available Expansive pedicle screws significantly improve fixation strength in osteoporotic spines. However, the previous literature does not adequately address the effects of the number of lengthwise slits and the extent of screw expansion on the strength of the bone/screw interface when expansive screws are used with or without cement augmentation. Herein, four designs for expansive pedicle screws with different numbers of lengthwise slits and different screw expansion levels were evaluated. Synthetic bones simulating severe osteoporosis were used to provide a comparative platform for each screw design. The prepared specimens were then tested for axial pullout failure. Regardless of screw design, screws with cement augmentation demonstrated significantly higher pullout strength than pedicle screws without cement augmentation (p 0.05. Taken together, our results show that pedicle screws combined with cement augmentation may greatly increase screw fixation regardless of screws with or without expansion. An increase in both the number of slits and the extent of screw expansion had little impact on the screw-anchoring strength. Cement augmentation is the most influential factor for improving screw pullout strength.

  5. Treatment of the thoracolumbar spine fracture with posterior monosegment pedicle fixation and transpedicular impacted bone graft at injured level%单节段椎弓根固定椎体内打压植骨治疗胸腰椎压缩骨折

    Institute of Scientific and Technical Information of China (English)

    邢飞; 樊道斌; 陈宏赋; 张林胜; 朱敏

    2012-01-01

    Objective To explore the clinical effects of posterior monosegmental pedicle screw fixation in selective treatment of thoracolumbar vertebral fractures. Methods 15 patients with thoracolumbar fractures were treated with posterior monosegmental pedicle screw fixation and transpedicle impacted bone graft. The Cobb's angle and reduction of injured vertebral body height were observed. Results All cases were followed up for 6 ~ 18months. Clinical evaluation revealed that 11 cases had no pain, 4 cases with occasional pain but required no medication and all patients had a high level of satisfaction with the final results. Radiographic evaluation revealed reduction rate of the injured vertebral height was 95%. The Cobb's angle was restored from 14° ~25° to 3° ~8°. There was no implant breakage, and no signs of pseudoarthrosis were observed. Conclusions Posterior monosegmental fixation might be an adequate and effective procedure to be used in specific types of thoracolumbar spine fractures. Transpedicular impacted grafting after bone loss calculation combined with pedicle fixation has better biomechanical properties.%目的 探讨单节段椎弓根固定结合伤椎打压植骨治疗胸腰椎屈曲压缩骨折的疗效.方法 对15例胸腰椎压缩性骨折(Denis B型)患者行后路单节段经伤椎复位固定、经椎弓根伤椎打压植骨手术.测量术前术后Cobb角,计算伤椎高度恢复率,进行ODI评分,分析疗效.结果 15例患者均获随访,时间6~18个月.伤椎高度矫正率约95%,Cobb角由术前的14°~25°改善为术后的3°~8°.未出现内固定断裂、神经损伤等并发症.结论 单节段椎弓根固定椎体内植骨治疗胸腰椎压缩性骨折手术创伤小,仅固定1个运动节段;椎体内打压植骨有效解决椎体复位后产生的椎体内骨缺损.

  6. A comparison of unilateral and bilateral pedicle screw fixation combined with transforaminal lumbar interbody fusion for lumbar degenerative diseases

    Institute of Scientific and Technical Information of China (English)

    Yang Xiaoming; Wang Hong; Zhao Quanlai; Xu Hongguang; Liu Ping; Jin Yuelong

    2014-01-01

    Background Bilateral transpedicular screw fixation in conjunction with interbody fusion is widely used to treat lumbar degenerative diseases; however,there are some disadvantages of using this fixation system.This study comparatively analyzes the results of unilateral and bilateral pedicle screw fixation combined with transforaminal lumbar interbody fusion (TLIF) for one-level lumbar degenerative diseases.Methods Sixty-six cases with one-level lumbar degenerative diseases were studied.The patients were divided according to surgical approach into a unilateral group (Group A) and a bilateral group (Group B).The patients were evaluated for pain by visual analog scale (VAS) and Oswestry Disability Index (ODI).Operating time,blood loss,duration of hospitalization,and complication rate were also evaluated.Patients were examined at 1,3,6,and 12 months postoperatively and every year thereafter.Results Group A patients' average preoperative VAS and ODI scores were 7.03 ± 0.98 and (64.22±6.38)%,respectively,significantly decreased to 2.91 ± 0.88 and (14.42±2.08)%,respectively,at the last follow-up (P =0.000).In Group B,the average preoperative VAS and ODI scores were 6.79±0.86 and (63.22±4.70)%,respectively,significantly decreased to 3.12±0.96 and (14.62±2.08)%,respectively,at the last follow-up (P=0.000).No significant difference in the duration of hospitalization was found between groups.Operating time and blood loss of (125.9±13.0) minutes and (211.4±28.3) ml,respectively,in Group A were significantly less than (165.2±15.3) minutes and (258.6±18.3) ml,respectively,in Group B (P=-0.000).All patients achieved good bone union and had no pseudarthrosis at the last follow-up.Conclusions There are no clinical differences between unilateral and bilateral pedicle screw fixation combined with TLIF for one-level lumbar degenerative diseases.Unilateral fixation reduces operating time,bleeding,and cost of hospitalization.

  7. Surgically assisted rapid palatal expansion with tent screws and a custom-made palatal expander: a case report.

    Science.gov (United States)

    Park, Kang-Nam; Lee, Chang Youn; Park, In Young; Kim, Jwa Young; Yang, Byoungeun

    2015-12-01

    Rapid palatal expansion(RPE) with the tooth-born appliance is not sufficient to apply to the patients with periodontal problem or insufficient tooth anchorage, and it leads to tipping of the anchorage teeth and increasing teeth mobility and root resorption. To avoid these disadvantages, we present the case using palatal screws and custommade palatal expander. A 23-year-old patient underwent surgically assisted rapid maxillary expansion with the Hyrax expansion using 4 tent screws. The study models were used to measure the pre-/-post surgical width of the anterior and posterior dental arches with a digital sliding caliper. In the result, the custom-made palatal expander with 4 tent screws is suitable for delivering a force to the mid-palatal suture expansion. And it is low cost, small sized and simply applied. The results indicated that maxillary expansion with the custom-made palatal anchorage device is predictable and stable technique without significant complications in patients.

  8. A Novel Approach to the Surgical Treatment of Lumbar Disc Herniations: Indications of Simple Discectomy and Posterior Transpedicular Dynamic Stabilization Based on Carragee Classification

    Directory of Open Access Journals (Sweden)

    A. F. Ozer

    2013-01-01

    Full Text Available Surgery of lumbar disc herniation is still a problem since Mixter and Barr. Main trouble is dissatisfaction after the operation. Today there is a debate on surgical or conservative treatment despite spending great effort to provide patients with satisfaction. The main problem is segmental instability, and the minimally invasive approach via microscope or endoscope is not necessarily appropriate solution for all cases. Microsurgery or endoscopy would be appropriate for the treatment of Carragee type I and type III herniations. On the other hand in Carragee type II and type IV herniations that are prone to develop recurrent disc herniation and segmental instability, the minimal invasive techniques might be insufficient to achieve satisfactory results. The posterior transpedicular dynamic stabilization method might be a good solution to prevent or diminish the recurrent disc herniation and development of segmental instability. In this study we present our experience in the surgical treatment of disc herniations.

  9. Twin Screw Mixer/Fine Grind Facility

    Data.gov (United States)

    Federal Laboratory Consortium — The 40-mm Twin-Screw Mixer/Extruder (TSE) pilot plant is a continuous, remotely operated, flexible facility that can significantly enhance safety and environmental...

  10. Clinical and radiological results 6 years after treatment of traumatic thoracolumbar burst fractures with pedicle screw instrumentation and balloon assisted endplate reduction

    NARCIS (Netherlands)

    Verlaan, Jorrit Jan; Somers, Inne; Dhert, Wouter J A; Oner, F. Cumhur

    2015-01-01

    Background context  When used to fixate traumatic thoracolumbar burst fractures, pedicle screw constructs may fail in the presence of severe vertebral body comminution as the intervertebral disc can creep through the fractured endplates leading to insufficient anterior column support. Balloon-assist

  11. 动力化前路方形区钛板螺钉系统固定伴有对侧骨盆前环不稳的髋臼双柱骨折的站位有限元分析%Finite element analysis of standing position in both-column with posterior hemi-transverse lesion fractures of the acetabulum fixed by dynamic anterior plate-screw system for quadrilateral area

    Institute of Scientific and Technical Information of China (English)

    林冠林; 陈庄洪; 蔡贤华; 刘曦明; 雷建银; 王志华; 张宝成

    2015-01-01

    Objective To explore biomechanical stability of fractures of the acetabulum fixed by dynamic anterior plate-screw system for quadrilateral area (DAPSQ) when pelvic ring was unstable.Methods To prepare right side of the anterior column with posterior hemi-transverse lesion fractures of the acetabulum (pelvis) by finite element analysis,DAPSQ (A),building on the left side of the superior ramus of pubis fracture and inferior ramus of pubis model on the basis of A model,prepare two kinds of model of the left side of the superior ramus fractures of pubis with fixed (B) and titanium plate fixation (C).Then,the same physiological load was exerted on different model respectively.At the end,the none-line solution was analyzed,analysis of the stress and displacement in model.Results After fracture fixation through the lateral and longitudinal displacement and the stress nephogram found after analysis and comparison,the transverse and longitudinal displacement is small with DAPSQ internal fixation when the stability of pelvic ring,accord with standard of reset,uniform stress distribution,no obvious phenomenon of highly concentrated,fixed intensity bigger,fixed the pelvis after more stable.But when accompanied by unstable pelvic ring road ahead for DAPSQ fracture line of vertical and horizontal displacement of the present B > C > A,A,B,C stations,the longitudinal displacement respectively (1.315 ±0.171),(1.490 ±0.247),(1.334 ±0.160) mm,lateral displacement of stations respectively (1.185 ±0.700),(1.337 ±0.080),(1.198 ± 0.103) mm.Conclusion The pelvic ring must be stable when treatment of anterior column with posterior hemi-transverse lesion fixed by DAPSQ.%目的 利用有限元技术探讨当对侧骨盆前环不稳时,动力化前路方形区钛板螺钉系统(DAPSQ)内固定治疗髋臼双柱骨折的生物力学稳定性.方法 利用有限元分析技术建立正常人体全骨盆有限元模型并进行有限元验证,建立3种骨折内固定模型:A:DAPSQ固

  12. Design and biomechanical study of a modified pedicle screw

    Institute of Scientific and Technical Information of China (English)

    LIU Tao; ZHENG Wen-jie; LI Chang-qing; LIU Guo-dong; ZHOU Yue

    2010-01-01

    Objective: In pedicle screw fixation,the heads of monoaxial screws need to be directed in the same straight line to accommodate the rod placement by backing out during operation, which decreases the insertional torque and internal fixation strength. While polyaxial screws facilitate the assembly of the connecting rod, but its ball-in-cup locking mechanism reduces the static compressive bending yield strength as compared with monoaxial screws. Our study aimed to assess the mechanical performance of a modified pedicle screw.Methods: In this study, the tail of the screw body of the modified pedicle screw was designed to be a cylindershaped structure that well matched the inner wall of the screw head and the screw head only rotated around the cyclinder. Monoaxial screws, modified screws and polyaxial screws were respectively assembled into 3 groups ofvertebrectomy models simulated by ultra high molecular weight polyethylene (UHMWPE) blocks. This model was developed according to a standard for destructive mechanical testing published by the American Society for Testing Materials (ASTM F1717-04). Each screw design had 6 subgroups, including 3 for static tension, load compression and torsion tests, and the rest for dynamic compression tests. In dynamic tests, the cyclic loads were 25%, 50%, and 75% of the compressive bending ultimate loads respectively.Yield load, yield ultimate load, yield stiffness, torsional stiffness, cycles to failure and modes of failure for the 3 types of screws were recorded. The results of modified screws were compared with those ofmonoaxial and polyaxial screws.Results: In static tests, results of bending stiffness,yield load, yield torque and torsional stiffness indicated no significant differences between the modified and monoaxial screws (P>0.05), but both differed significantly from those ofpolyaxial screws (P<0.05). In dynamic compression tests,both modified and monoaxial screws showed failures that occurred at the insertion point of screw

  13. Ball Screw Actuator Including a Stop with an Integral Guide

    Science.gov (United States)

    Wingett, Paul T. (Inventor); Perek, John (Inventor); Geck, Kellan (Inventor)

    2015-01-01

    An actuator includes a housing assembly, a ball nut, a ball screw, and a ball screw stop. The ball nut is rotationally mounted in the housing assembly, is adapted to receive an input torque, and is configured, upon receipt thereof, to rotate and supply a drive force. The ball screw is mounted within the housing assembly and extends through the ball nut. The ball screw has a first end and a second end, and is coupled to receive the drive force from the ball nut. The ball screw is configured, upon receipt of the drive force, to selectively translate between a stow position and a deploy position. The ball screw stop is mounted on the ball screw to translate therewith and is configured to at selectively engage the housing assembly while the ball screw is translating, and engage the ball nut when the ball screw is in the deploy position.

  14. Flow characteristics of screws and special mixing enhancers in a co-rotating twin screw extruder

    NARCIS (Netherlands)

    Brouwer, T.; Todd, D.B.; Janssen, L.P.B.M.

    2002-01-01

    The flow behavior of a Newtonian fluid through special mixing enhancers in a modular intermeshing co-rotating twin screw extruder has been examined. The mixing enhancers are slotted screws and gear mixing elements. Particular attention has been directed to drag and pressure flow characteristics and

  15. Pullout strength of pedicle screws with cement augmentation in severe osteoporosis: A comparative study between cannulated screws with cement injection and solid screws with cement pre-filling

    Directory of Open Access Journals (Sweden)

    Lee Yen-Chen

    2011-02-01

    Full Text Available Abstract Background Pedicle screws with PMMA cement augmentation have been shown to significantly improve the fixation strength in a severely osteoporotic spine. However, the efficacy of screw fixation for different cement augmentation techniques, namely solid screws with retrograde cement pre-filling versus cannulated screws with cement injection through perforation, remains unknown. This study aimed to determine the difference in pullout strength between conical and cylindrical screws based on the aforementioned cement augmentation techniques. The potential loss of fixation upon partial screw removal after screw insertion was also examined. Method The Taguchi method with an L8 array was employed to determine the significance of design factors. Conical and cylindrical pedicle screws with solid or cannulated designs were installed using two different screw augmentation techniques: solid screws with retrograde cement pre-filling and cannulated screws with cement injection through perforation. Uniform synthetic bones (test block simulating severe osteoporosis were used to provide a platform for each screw design and cement augmentation technique. Pedicle screws at full insertion and after a 360-degree back-out from full insertion were then tested for axial pullout failure using a mechanical testing machine. Results The results revealed the following 1 Regardless of the screw outer geometry (conical or cylindrical, solid screws with retrograde cement pre-filling exhibited significantly higher pullout strength than did cannulated screws with cement injection through perforation (p = 0.0129 for conical screws; p = 0.005 for cylindrical screws. 2 For a given cement augmentation technique (screws without cement augmentation, cannulated screws with cement injection or solid screws with cement pre-filling, no significant difference in pullout strength was found between conical and cylindrical screws (p >0.05. 3 Cement infiltration into the open cell of

  16. Wiltse入路经椎弓根植骨治疗胸腰椎骨折%Transpedicular bone graft for the treatment of thoracolumbar vertebral fractures through Wiltse approach

    Institute of Scientific and Technical Information of China (English)

    王想福; 王兴盛

    2013-01-01

    age from 14 to 55 years old (mean,41 years old).The time from injury to operation from 2 to 15 d(mean,3 d).Twenty-five cases were caused by falling down,7 cases were caused by slipping,'20 cases were caused by car accident and 4 cases were caused by crush trauma.MRI was performed before operation to exclude pathological fracture.The distance between multifidus muscle and longissimus to midcourt line was measured.Self-made trocar was applied in operation.According to AO classification,there were 33 cases with type A1 compression fracture,5 cases with type A2 cleavage fracture and 18 cases with type A3 burst fracture.Sixteen cases of the 56 cases combined with spinal cord injury.Based on Frankel neurologic grading system,preoperative neurological function was grade B in 5 cases,grade C in 2 cases,gade D in 9 cases.Preoperative Denis gading were P5.Frankel and lumbago Denis clssification were used to evaluate neurological function and lumbago.The imaging data before,after operation and the latest follow-up were used to evaluate correction vision.Results:All patients were followed up over 24 months.At the time of the latest follow-up,Frankel B were 3 cases,Frankel C were 2 cases,Frankel D were 4 cases and Frankel E were 7 cases.According to lumbago Denis clssification,P1 (painlessness) were 32 cases,P2 (slight pain without treatment) were 18 cases,P3 (moderate pain and taking medicine occasionally) were 6 cases.The anterior vertebral height improved from preoperative (13.38±4.72) mm to postoperative (22.18± 1.44) mm.The Cobb's angle decreased from preoperative (28.39±2.64) ° to (10.07±3.05)°.There were no nails broken,rod broken,internal fixation lossen and vertebral body recompression.Conclusion:Transpedicular bone graft for thoracolumbar fractures through Wiltse approach can reduce intraoperative blood loss and postoperative complications,and aviod "eggshell" vertebral body.Mastering revealed way,drafting detailed preoperative plan and eariler exercise is the key

  17. Standard Waste Box Lid Screw Removal Option Testing

    Energy Technology Data Exchange (ETDEWEB)

    Anast, Kurt Roy [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2016-03-11

    This report provides results from test work conducted to resolve the removal of screws securing the standard waste box (SWB) lids that hold the remediated nitrate salt (RNS) drums. The test work evaluated equipment and process alternatives for removing the 42 screws that hold the SWB lid in place. The screws were secured with a red Loctite thread locker that makes removal very difficult because the rivets that the screw threads into would slip before the screw could be freed from the rivet, making it impossible to remove the screw and therefore the SWB lid.

  18. Biomechanical analysis on transverse tibial fixation in anterior cruciate ligament reconstructions

    Directory of Open Access Journals (Sweden)

    Edmar Stieven Filho

    2015-04-01

    Full Text Available OBJECTIVE: To verify whether the combination of tibial cross pin fixation and femoral screw fixation presents biomechanical advantages when compared to femoral cross pin fixation and tibial screw fixation for the reconstruction of the anterior cruciate ligament (ACL.METHODS: Thirty-eight porcine knees and bovine extensor digitorum tendons were used as the graft materials. The tests were performed in three groups: (1 standard, used fourteen knees, and the grafts were fixated with the combination of femoral cross pin and a tibial screw; (2 inverted, used fourteen knees with an inverted combination of tibial cross pin and a femoral screw; (3 control, ten control tests performed with intact ACL. After the grafts fixation, all the knees were subjected to tensile testing to determine yield strength and ultimate strength.RESULTS: There was no statistically significant difference in survival techniques in regard to strength, yield load and tension. There was a higher survival compared in the standard curves of yield stress (p < 0.05.CONCLUSION: There is no biomechanical advantage, observed in animal models testing, in the combination of tibial cross pin fixation and femoral screw when compared to femoral cross pin fixation and tibial screw.

  19. CONGENITAL ANTERIOR TIBIOFEMURAL SUBLUXATION

    Directory of Open Access Journals (Sweden)

    A. Shahla

    2008-06-01

    Full Text Available Congenital anterior tibiofemoral subluxation is an extremely rare disorder. All reported cases accompanied by other abnormalities and syndromes. A 16-year-old high school girl referred to us with bilateral anterior tibiofemoral subluxation as the knees were extended and reduced at more than 30 degrees flexion. Deformities were due to tightness of the iliotibial band and biceps femuris muscles and corrected by surgical release. Associated disorders included bilateral anterior shoulders dislocation, short metacarpals and metatarsals, and right calcaneuvalgus deformity.

  20. Twin screw wet granulation: Binder delivery.

    Science.gov (United States)

    Saleh, Mohammed F; Dhenge, Ranjit M; Cartwright, James J; Hounslow, Michael J; Salman, Agba D

    2015-06-20

    The effects of three ways of binder delivery into the twin screw granulator (TSG) on the residence time, torque, properties of granules (size, shape, strength) and binder distribution were studied. The binder distribution was visualised through the transparent barrel using high speed imaging as well as quantified using offline technique. Furthermore, the effect of binder delivery and the change of screw configuration (conveying elements only and conveying elements with kneading elements) on the surface velocity of granules across the screw channel were investigated using particle image velocimetry (PIV). The binder was delivered in three ways; all solid binder incorporated with powder mixture, 50% of solid binder mixed with powder mixture and 50% mixed with water, all the solid binder dissolved in water. Incorporation of all solid binder with powder mixture resulted in the relatively longer residence time and higher torque, narrower granule size distribution, more spherical granules, weaker big-sized granules, stronger small-sized granules and better binder distribution compared to that in other two ways. The surface velocity of granules showed variation from one screw to another as a result of uneven liquid distribution as well as shown a reduction while introducing the kneading elements into the screw configuration.

  1. [Cement augmentation of pedicle screws : Pros and cons].

    Science.gov (United States)

    Schnake, K J; Blattert, T R; Liljenqvist, U

    2016-09-01

    Cement augmentation of pedicle screws biomechanically increases screw purchase in the bone. However, clinical complications may occur. The pros and cons of the technique are discussed from different clinical perspectives.

  2. Impact of screw configuration on the particle size distribution of granules produced by twin screw granulation.

    Science.gov (United States)

    Vercruysse, J; Burggraeve, A; Fonteyne, M; Cappuyns, P; Delaet, U; Van Assche, I; De Beer, T; Remon, J P; Vervaet, C

    2015-02-01

    Twin screw granulation (TSG) has been reported by different research groups as an attractive technology for continuous wet granulation. However, in contrast to fluidized bed granulation, granules produced via this technique typically have a wide and multimodal particle size distribution (PSD), resulting in suboptimal flow properties. The aim of the current study was to evaluate the impact of granulator screw configuration on the PSD of granules produced by TSG. Experiments were performed using a 25 mm co-rotating twin screw granulator, being part of the ConsiGma™-25 system (a fully continuous from-powder-to-tablet manufacturing line from GEA Pharma Systems). Besides the screw elements conventionally used for TSG (conveying and kneading elements), alternative designs of screw elements (tooth-mixing-elements (TME), screw mixing elements (SME) and cutters) were investigated using an α-lactose monohydrate formulation granulated with distilled water. Granulation with only conveying elements resulted in wide and multimodal PSD. Using kneading elements, the width of the PSD could be partially narrowed and the liquid distribution was more homogeneous. However, still a significant fraction of oversized agglomerates was obtained. Implementing additional kneading elements or cutters in the final section of the screw configuration was not beneficial. Furthermore, granulation with only TME or SME had limited impact on the width of the PSD. Promising results were obtained by combining kneading elements with SME, as for these configurations the PSD was narrower and shifted to the size fractions suitable for tableting.

  3. A modified technique for removing a failed abutment screw from an implant with a custom guide tube.

    Science.gov (United States)

    Taira, Yohsuke; Sawase, Takashi

    2012-04-01

    Fracture of abutment screw is a serious prosthodontic complication. When the abutment screw is fractured at the junction of the screw shank and screw thread, removal of the fractured screw fragment from the screw hole can be difficult. This article describes a modified technique for removing the failed abutment screw with a custom guide tube and tungsten carbide bur. The failed screw can be removed speedily without damaging the screw hole of the implant body or the screw threads.

  4. Treatment of thoracolumbar fractures with vertebral body bone graft through pedicle and transpedicular fixation via fractured vertebra%伤椎置钉并椎体内植骨内固定术在胸腰椎骨折治疗中的应用

    Institute of Scientific and Technical Information of China (English)

    秦入结; 宋波; 李垠; 盛路新; 刘建; 孙晓

    2012-01-01

    目的 观察伤椎置钉并椎体内植骨内固定术在胸腰椎骨折治疗中的应用效果.方法 至少一侧椎弓根完整的胸腰椎骨折26例,予伤椎撬拨复位置钉、椎体内植骨、椎弓根内固定,据胸腰段正侧位片比较术前、术后即刻、术后6个月的椎体高度及Cobb's角,并评估脊髓神经功能和融合情况.结果 术后随访7~28个月.患者术后即刻伤椎椎体前缘高度占正常高度百分比及Cobb's角优于术前(P均<0.05);伤椎外形恢复满意;按ASIA脊髓神经功能分级,伴神经损伤者15例中,A级1例无恢复,余均改善1~3级(P均<0.05),内固定无失效,植骨皆融合.结论 伤椎置钉并椎体内植骨内固定术治疗胸腰椎骨折可重建椎体结构,增强脊柱稳定,近期疗效较好.%Objective To observe the outcome of vertebral body bone grafting throughpedicle combined with transpedicular fixation via fractured vertebra in the treatment of thoracolumbar fractures, and explore the operation methods. Methods 26 cases of thoracolumbar fractures, which had at least one side pedicle complete , were treated with posterior pedicle fixation by leverage, bone graft through pedicle and transpedicular fixation via fractured vertebra. According to the data of thoracolumbar radiograph, the anterior vertebral height and Cobb's angle of preoperation, postoperation instantly and after 6 monthswere compared. Their fusion results and neurological functions were observed. Results The follow-up period was 7 to 28 months . There were significant differences in the percentage of anterior vertebral height to the normal and Gobb's angle between preoperation and postoperation instantly (all P <0. 05). The shape of injured vertebra were restored satisfactorily . The spinal cord function was classified by ASIA's scale, it was improved 1 to 3 degree in all cases( 15 cases) of pre-operative neurological injury except of one case of grade A (all P < 0. 05). There was no case of fixation

  5. A processing method for orthodontic mini-screws reuse

    Directory of Open Access Journals (Sweden)

    Saeed Noorollahian

    2012-01-01

    Conclusion: Cleaning of used mini-screws with phosphoric acid 37% (10 minutes and sodium hypochlorite 5.25% (30 minutes reduces tissue remnants to the level of as-received mini-screws. So it can be suggested as a processing method of used mini-screws. Previous insertion of mini-screws into the bone and above-mentioned processing method and resterilization with autoclave had no adverse effects on insertion, removal, and fracture torque values as mechanical properties indices.

  6. Tangential View and Intraoperative Three-Dimensional Fluoroscopy for the Detection of Screw-Misplacements in Volar Plating of Distal Radius Fractures

    Directory of Open Access Journals (Sweden)

    Rausch

    2015-06-01

    Full Text Available Background Volar locking plate fixation has become the gold standard in the treatment of unstable distal radius fractures. Juxta-articular screws should be placed as close as possible to the subchondral zone, in an optimized length to buttress the articular surface and address the contralateral cortical bone. On the other hand, intra-articular screw misplacements will promote osteoarthritis, while the penetration of the contralateral bone surface may result in tendon irritations and ruptures. The intraoperative control of fracture reduction and implant positioning is limited in the common postero-anterior and true lateral two-dimensional (2D-fluoroscopic views. Therefore, additional 2D-fluoroscopic views in different projections and intraoperative three-dimensional (3D fluoroscopy were recently reported. Nevertheless, their utility has issued controversies. Objectives The following questions should be answered in this study; 1 Are the additional tangential view and the intraoperative 3D fluoroscopy useful in the clinical routine to detect persistent fracture dislocations and screw misplacements, to prevent revision surgery? 2 Which is the most dangerous plate hole for screw misplacement? Patients and Methods A total of 48 patients (36 females and 13 males with 49 unstable distal radius fractures (22 x 23 A; 2 x 23 B, and 25 x 23 C were treated with a 2.4 mm variable angle LCP Two-Column volar distal radius plate (Synthes GmbH, Oberdorf, Switzerland during a 10-month period. After final fixation, according to the manufactures' technique guide and control of implant placement in the two common perpendicular 2D-fluoroscopic images (postero-anterior and true lateral, an additional tangential view and intraoperative 3D fluoroscopic scan were performed to control the anatomic fracture reduction and screw placements. Intraoperative revision rates due to screw misplacements (intra-articular or overlength were evaluated. Additionally, the number of

  7. A geometrical introduction to screw theory

    CERN Document Server

    Minguzzi, E

    2012-01-01

    Since the addition of applied forces must take into account the line of action, applied forces do not belong to a vector space. Screw theory removes this geometrical limitation and solves other mechanical problems by unifying, in a single concept, the translational and rotational degrees of freedom. Although venerable this theory is little known. By introducing some innovations, I show how screw theory can help us to rapidly develop several standard and less standard results in classical mechanics. The connection with the Lie algebra of the group of rigid maps is clarified.

  8. Drag and Torque on Locked Screw Propeller

    Directory of Open Access Journals (Sweden)

    Tomasz Tabaczek

    2014-09-01

    Full Text Available Few data on drag and torque on locked propeller towed in water are available in literature. Those data refer to propellers of specific geometry (number of blades, blade area, pitch and skew of blades. The estimation of drag and torque of an arbitrary propeller considered in analysis of ship resistance or propulsion is laborious. The authors collected and reviewed test data available in the literature. Based on collected data there were developed the empirical formulae for estimation of hydrodynamic drag and torque acting on locked screw propeller. Supplementary CFD computations were carried out in order to prove the applicability of the formulae to modern moderately skewed screw propellers.

  9. Screw Extruder for Pellet Injection System

    Directory of Open Access Journals (Sweden)

    Sharadkumar K. Chhantbar

    2014-05-01

    Full Text Available Solid hydrogenic pellets are used as fuel for fusion energy reactor. A technique for continuous production of solid hydrogen and its isotopes by a screw extruder is suggested for the production of an unlimited number of pellets. The idea was developed and patented by PELIN laboratories, Inc. (Canada. A Gifford McMahon cryocooler is used for the generation of solid hydrogenic fluid pellets. Requirements of the pellets is depends upon the energy to be produced by tokamak. This review paper focuses on the model for the screw extruder for solidification of hydrogen ice having high injection reliability.

  10. Estudo histomorfométrico da interface óssea do parafuso expansor cervical Histomorphometric analysis of bone-screw interface of expansive cervical screw

    Directory of Open Access Journals (Sweden)

    Leandro Sérgio da Silva

    2008-03-01

    experimental study for the Histomorphometric analysis of the bone interface of expansive screws used in the anterior cervical spine fixation system. METHODS: Five sheep cervical vertebrae (C4 were used in the study, in which screws were inserted. The 18.5 mm long and 5.0 mm outer diameter expansive screws (Ulrich were inserted in both sides of the C4 vertebra. On the left side, the screw was inserted without the internal expansive screw, which was used on the right side. A pilot hole was made on the lower portion of the vertebra with a 2.5 mm bore, but no implant was introduced. The vertebral region containing the screws and the pilot hole was prepared for a histological study of the interface between implants and bone screws, and of the pilot hole wall. Histomorphometric analysis evaluated total bone density, external bone density (outside the screw thread, internal density (inside the screw thread and the linear measurement of the contact between bone tissue and the implant. RESULTS: Total bone density was greater in group I (expansive screw as compared to group III (control. External bone density was greater in groups I (expansive screw and II (non-expansive screw when compared to group III. Internal bone density was greater in group I when compared to groups II and III, and greater in group II when compared to group III. Linear contact was greater in group I when compared to groups II and III. CONCLUSION: structural changes around expansive screws detected immediately after their application provide subsidies for a better understanding of the greater tearing resistance of the implant, which could be related to the compacting of cancellous bone around the implant, while providing a larger contact area between the implant and the bone tissue.

  11. 21 CFR 872.4880 - Intraosseous fixation screw or wire.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Intraosseous fixation screw or wire. 872.4880... (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Surgical Devices § 872.4880 Intraosseous fixation screw or wire. (a) Identification. An intraosseous fixation screw or wire is a metal device intended to be...

  12. The additon of screws and the axodes of gear pairs

    Institute of Scientific and Technical Information of China (English)

    ZHANG Wen-xiang

    2001-01-01

    In the light of screw addition, the distribution of instantaneous axes along the common perpendicular of the two screws is determined and all possible sorts of axodes are derived cinematically with the pitch of the relative-motio n screw in the gear pair as the basis and the transmission ratio i as an inde pendent variable.

  13. The additon of screws and the axodes of gear pairs

    Institute of Scientific and Technical Information of China (English)

    张文祥

    2001-01-01

    In the light of screw addition, the distribution of instantaneous axes along the common perpendicular of the two screws is determined and all possible sorts of axodes are derived cinematically with the pitch of the relative-motion screw in the gear pair as the basis and the transmission ratio i as an independent variable.

  14. Biomechanical evaluation of an expansive pedicle screw in calf vertebrae

    Institute of Scientific and Technical Information of China (English)

    雷伟; 吴子祥

    2005-01-01

    Objective: To obtain a comprehensive understanding of the effect of the improvement of fixation strength of a newly designed expansive pedicle screw through biomechanical analyses.Metheds: 100 (200 pedicles) fresh calf lumber vertebrae were used. A total of four instrumentation systems were tested including CDH (CD Horizon), USS (Universal Spine System pedicle screw), Tenor (Sofamor Denek) and expansive pedicle screw (EPS). Pullout and turning-back tests were performed to compare the holding strength of the expansive pedicle screw with conventional screws, i.e. USS, CDH and Tenor. Revision tests were performed to evaluate the mechanical properties of the expansive pedicle screw as a "rescue" revision screw. A fatigue simulation using perpendicular load up to 1 500 000 cycles was carried out.Results: The turning back torque (Tmax) and pull-out force (Fmax) of EPS were significantly greater than those of USS, Tenor and CDH screws (6.5 mm×40 mm). In revision tests, the Fmax of both kinds of EPS (6.5 mm×40 mm; 7.0 mm×40 mm) were greater than that of CDH, USS and Tenor screws significantly (P<0.05). No screws were broken or bent at the end of fatigue tests.Conclusions: EPS can significantly improve the bone purchase and the pull-out strength compared to USS, Tenor and CDH screws with similar dimensions before and after failure simulation. The fatigue characteristic of EPS is similar to that of CDH, USS and Tenor screws.

  15. A Novel Pedicle Screw with Mobile Connection: A Pilot Study

    Directory of Open Access Journals (Sweden)

    Yasuaki Tokuhashi

    2014-01-01

    Full Text Available To prevent adjacent disc problems after spinal fusion, a pedicle screw with a mobile junction between the head and threaded shaft was newly developed. The threaded shaft of the screw has 10 degrees mobility in all directions, but its structure is to prevent abnormal translation and tilting. This screw was evaluated as follows: (1 endurance test: 106 times rotational stress was applied; (2 biological reactions: novel screws with a mobile head and conventional screws with a fixed head were inserted into the bilateral pedicles of the L3, L4, and L5 in two mini pigs with combination. Eight months after surgery, vertebral units with the screw rod constructs were collected. After CT scan, the soft and bony tissues around the screws were examined grossly and histologically. As a result, none of the screws broke during the endurance test stressing. The mean amount of abrasion wear was 0.0338 g. In the resected mini pig section, though zygapophyseal joints between fixed-head screws showed bony union, the amount of callus in the zygapophyseal joints connected with mobile-head screws was small, and joint space was confirmed by CT. No metalloses were noted around any of the screws. Novel screws were suggested to be highly durable and histologically safe.

  16. Dual-worm screw compressors; Compresseurs bi-vis

    Energy Technology Data Exchange (ETDEWEB)

    Baleydier, J.P. [Bitzer France, 69 - Lyon (France)

    1997-12-31

    Low power worm-screw moto-compressors are used in any king of refrigerating machineries and more and more in air conditioning systems. This paper presents the principle of dual-screw moto-compressors: worm-screw technology, role of oil (lubrication, tightness, cooling), compression, internal pressure, power reduction, lubrication, economizer, operation, model selection and accessories. (J.S.)

  17. Design of a magnetic lead screw for wave energy conversion

    DEFF Research Database (Denmark)

    Holm, Rasmus Koldborg; Berg, Nick Ilsø; Rasmussen, Peter Omand

    2012-01-01

    This paper deals with the development of a magnetic lead screw (MLS) for wave energy conversion. Initially, a brief state-of-the-art regarding linear PM generators and magnetic lead screws is given, leading to an introduction of the magnetic lead screw and a presentation of the results from...

  18. Anterior cervical fusion with the Caspar instrumentation system.

    Science.gov (United States)

    Naito, M; Kurose, S; Oyama, M; Sugioka, Y

    1993-01-01

    We reviewed 106 consecutive patients who had undergone anterior cervical fusion with the Caspar instrumentation system between 1984 and 1989. Preoperative diagnoses were cervical spondylosis in 73 patients, a traumatic lesion in 12, ossification of the posterior longitudinal ligament in 9, cervical disc herniation in 6, and tumour or miscellaneous lesions in 6. In the 106 patients, 56 had two levels fused and 27 had three levels fused. At an average duration of follow-up of 4 years and 7 months, nonunion occurred in 3 of the 83 patients with multiple level fusions. Screw loosening occurred in 8 of the 106 patients, but there was no oesophageal perforation.

  19. Clinical pedicle screw accuracy and deviation from planning in robot-guided spine surgery: robot-guided pedicle screw accuracy

    NARCIS (Netherlands)

    Dijk, van Joris D.; Ende, Roy P.J.; Stramigioli, Stefano; Köchling, Matthias; Höss, Norbert

    2015-01-01

    STUDY DESIGN: A retrospective chart review was performed for 112 consecutive minimally invasive spinal surgery patients who underwent pedicular screw fixation in a community hospital setting. OBJECTIVE: To assess the clinical accuracy and deviation in screw positions in robot-assisted pedicle screw

  20. Anterior Cruciate Ligament (ACL) Injuries

    Science.gov (United States)

    ... Week of Healthy Breakfasts Shyness Anterior Cruciate Ligament (ACL) Injuries KidsHealth > For Teens > Anterior Cruciate Ligament (ACL) ... and Recovery Coping With an ACL Injury About ACL Injuries A torn anterior cruciate ligament (ACL) is ...

  1. Treatment of neuromuscular scoliosis with posterior-only pedicle screw fixation

    Directory of Open Access Journals (Sweden)

    Fernandez Harry M

    2008-06-01

    Full Text Available Abstract Background To determine whether posterior-only approach using pedicle screws in neuromuscular scoliosis population adequately addresses the correction of scoliosis and maintains the correction over time. Methods Between 2003 and 2006, 26 consecutive patients (7 cerebral palsy, 10 Duchenne muscular dystrophy, 5 spinal muscular atrophy and 4 others with neuromuscular scoliosis underwent posterior pedicle screw fixation for the deformity. Preoperative, immediate postoperative and final follow-up Cobb's angle and pelvic obliquity were analyzed on radiographs. The average age of the patients was 17.5 years (range, 8–44 years and the average follow-up was 25 months (18–52 months. Results Average Cobb's angle was 78.53° before surgery, 30.70° after surgery (60.9% correction, and 33.06° at final follow-up (57.9% correction showing significant correction (p Conclusion Results indicate that in patients with neuromuscular scoliosis, acceptable amounts of curve correction can be achieved and maintained with posterior-only pedicle screw instrumentation without anterior release procedure.

  2. Nylon screws make inexpensive coil forms

    Science.gov (United States)

    Aucoin, G.; Rosenthal, C.

    1978-01-01

    Standard nylon screws act as coil form copper wire laid down in spiral thread. Completed coil may be bonded to printed-circuit board. However, it is impossible to tune coil by adjusting spacing between windings, technique sometimes used with air-core coils.

  3. A phenomenological study on twin screw extruders

    NARCIS (Netherlands)

    Janssen, L.P.B.M.

    1976-01-01

    Although more and more twin screw extruders are being used in the polymer industry, the theoretical background is relatively undeveloped. The literature abounds in contradictions and often informs the reader that all extrusion problems can be solved if a certain new design is considered. The develop

  4. Atlantoaxial stabilization using multiaxial C-1 posterior arch screws.

    Science.gov (United States)

    Donnellan, Michael B; Sergides, Ioannis G; Sears, William R

    2008-12-01

    The authors present a novel technique of atlantoaxial fixation using multiaxial C-1 posterior arch screws. The technique involves the insertion of bilateral multiaxial C-1 posterior arch screws, which are connected by crosslinked rods to bilateral multiaxial C-2 pars screws. The clinical results are presented in 3 patients in whom anomalies of the vertebral arteries, C-1 lateral masses, and/or posterior arch of C-1 presented difficulty using existing fixation techniques with transarticular screws, C-1 lateral mass screws, or posterior wiring. The C-1 posterior arch screws achieved solid fixation and their insertion appeared to be technically less demanding than that of transarticular or C-1 lateral mass screws. This technique may reduce the risk of complications compared with existing techniques, especially in patients with anatomical variants of the vertebral artery, C-1 lateral masses, or C-1 posterior arch. This technique may prove to be an attractive fixation option in patients with normal anatomy.

  5. Rotational Efficiency of Photo-Driven Archimedes Screws for Micropumps

    Directory of Open Access Journals (Sweden)

    Chih-Lang Lin

    2015-06-01

    Full Text Available In this study, we characterized the rotational efficiency of the photo-driven Archimedes screw. The micron-sized Archimedes screws were fabricated using the two-photon polymerization technique. Free-floating screws trapped by optical tweezers align in the laser irradiation direction and rotate spontaneously. The influences of the screw pitch and the number of screw blades have been investigated in our previous studies. In this paper, the blade thickness and the central rod of the screw were further investigated. The experimental results indicate that the blade thickness contributes to rotational stability, but not to rotational speed, and that the central rod stabilizes the rotating screw but is not conducive to rotational speed. Finally, the effect of the numerical aperture (NA of the optical tweezers was investigated through a demonstration. The NA is inversely proportional to the rotational speed.

  6. A Review of Screw Conveyors Performance Evaluation During Handling Process

    Directory of Open Access Journals (Sweden)

    Hemad Zareiforoush

    2010-04-01

    Full Text Available This paper reviews recent work on screw conveyors performance evaluation during handling process, especially in the case of agricultural grains and bulk materials. Experimental work has been mainly carried out to determine a range of parameters, such as auger dimension, screw rotational speed, screw clearance, conveyor intake length and conveying angle for horizontal, inclined and vertical screw conveyors. Several measurement techniques including theoretical models and DEM have been utilized to study the screw conveyors performance. However, each of these techniques is limited in its application. Difficulties in representing vortex motion and interactions among conveying grains and between the particles and screw rotating flight have so far limited the success of advanced modeling. Further work is needed to be conducted on screw augers performance to understand and improve the agricultural grains and bulk materials handling process.

  7. Anterior cervical plating

    Directory of Open Access Journals (Sweden)

    Gonugunta V

    2005-01-01

    Full Text Available Although anterior cervical instrumentation was initially used in cervical trauma, because of obvious benefits, indications for its use have been expanded over time to degenerative cases as well as tumor and infection of the cervical spine. Along with a threefold increase in incidence of cervical fusion surgery, implant designs have evolved over the last three decades. Observation of graft subsidence and phenomenon of stress shielding led to the development of the new generation dynamic anterior cervical plating systems. Anterior cervical plating does not conclusively improve clinical outcome of the patients, but certainly enhances the efficacy of autograft and allograft fusion and lessens the rate of pseudoarthrosis and kyphosis after multilevel discectomy and fusions. A review of biomechanics, surgical technique, indications, complications and results of various anterior cervical plating systems is presented here to enable clinicians to select the appropriate construct design.

  8. Applied anatomy of the lower cervical pedicle screw insertion

    Institute of Scientific and Technical Information of China (English)

    LI Xing-guo; LIU Zong-liang; HE Yun; ZHAO Yan; ZOU Zhi-rong; ZHANG Peng; LUO Ji-hong; GUO Yong-fu; ZHANG Yang-jie; ZHANG Yu-ran

    2007-01-01

    Objective: To ascertain an accurate approach to inserting the pedicle screw into C3-C7 segments of the cervical vertebra.Methods: Anatomic morphology of lateral mass and pedicle, and their anatomic relationship with the adjacent tissue were observed on C3-C7 segments of 25 adult embalmed cadavers (50 sides).Results: 1 ) The inferior edge of the base of the posterior tubercle of the transverse process and the inferior edge of the pedicle were connected with each other on 25 adult embalmed cadavers (50 sides ). The transverse section which passed through the median point between the superior edge and the inferior edge of the base of the posterior tubercle of the transverse process, and the transverse section which passed through the central axis between the superior edge and the inferior edge of the pedicle, were in the same horizontal plane. The superior and inferior position of placing the pedicle screw was determined by this transverse section, which passed through the median point between the superior and the inferior edge of the base of the posterior tubercle of the transverse process. 2 ) There was a directed internaldownwards "triangular sulcule" between the base of the posterior tubercle of the transverse process and the anterolateral edge of the inferior articular process. The anterior wall of the triangular sulcule was the base of the posterior tubercle of the transverse process, the posterior wall was the anterolateral edge of the inferior articular process, and the bottom of the sulcule was connected with the interior edge of the pedicle. The vertical length between the top of triangle and the planes of inferior edge of the pedicle was (2.78 ± 1.71 ) mm. The inferior edge of the cervical pedicle could be detected using a blunt probe along the "triangular sulcule" between the base of the posterior tubercle of the transverse process and the anterolateral edge of the inferior articular process in surgical operation. 3 )The lateral fovea of the articular

  9. Research and application of absorbable screw in orthopedics: a clinical review comparing PDLLA screw with metal screw in patients with simple medial malleolus fracture

    Directory of Open Access Journals (Sweden)

    TANG Jin

    2013-02-01

    Full Text Available 【Abstract】Objective: To observe the therapeutic effect of absorbable screw in medial malleolus fracture and discuss its clinical application in orthopedics. Methods: A total of 129 patients with simple medial malleolus fracture were studied. Among them, 64 patients were treated with poly-D, L-lactic acid (PDLLA absorbable screws, while the others were treated with metal screws. All the patients were followed up for 12-20 months (averaged 18.4 months and the therapeutic effect was evaluated ac-cording to the American Orthopaedic Foot and Ankle Soci-ety clinical rating systems. Results: In absorbable screw group, we obtained excel-lent and good results in 62 cases (96.88%; in steel screw group, 61 cases (93.85% achieved excellent and good results. There was no significant difference between the two groups. Conclusion: In the treatment of malleolus fracture, absorbable screw can achieve the same result compared with metal screw fixation. Absorbable screw is preferred due to its advantages of safety, cleanliness and avoiding the removal procedure associated with metallic implants. Key words: Ankle; Bone screws; Fractures, bone

  10. Closed reduction with CT-guided screw fixation for unstable sacroiliac joint fracture-dislocation

    Energy Technology Data Exchange (ETDEWEB)

    Baskin, Kevin M.; Cahill, Ann Marie; Kaye, Robin D. [Children' s Hospital of Philadelphia, Department of Radiology, Philadelphia, PA (United States); Born, Christopher T. [Temple University Hospital/Temple Children' s Hospital, Temple Sports Medicine, Marlton, NJ (United States); Grudziak, Jan S. [Children' s Hospital of Pittsburgh, Department of Orthopedic Surgery, Pittsburgh, PA (United States); Towbin, Richard B.

    2004-12-01

    Unstable posterior pelvic ring fractures and dislocations are uncommon but potentially life-threatening injuries in children. Early definitive management reduces risk of immediate complications as well as chronic pain and gait dysfunction. Conventional operative therapy carries substantial risk of extensive blood loss and iatrogenic neurological and vascular injury. Minimally invasive image-guided intervention may further reduce immediate risk and improve long-term outcome. To describe CT-guided closed reduction and internal fixation (CRIF) and review outcomes of unstable fracture-dislocation of the sacroiliac (SI) joint in children. Between 2000 and 2003, three children (two girls, one boy) age 8-14 years were referred to interventional radiology for treatment of unstable SI joint fracture-dislocation not adequately treated with anterior external fixation alone. The three affected SI joints (two left, one right) were treated in a combined approach by pediatric interventional radiologists and orthopedic surgeons, using a percutaneous approach under CT guidance. Over a threaded guiding pin, 7.3 mm cannulated screws were used to achieve stable reduction of the affected SI joints. One screw was removed after slight (2 mm) migration. No neurovascular or other complications occurred. All patients had satisfactory healing with near-anatomic reduction, although recovery of the youngest was delayed by associated spinal injury. Compared to open surgical alternatives, CRIF under CT guidance reduces operating time, decreases blood loss, and allows early definitive fixation and immediate non-weight-bearing mobilization with a low rate of complication for unstable posterior pelvic ring fractures. In addition, CT-guided placement of the guide pin may allow safer screw positioning and may minimize the total number of screws needed to achieve pelvic stability. (orig.)

  11. Surgical complications in neuromuscular scoliosis operated with posterior- only approach using pedicle screw fixation

    Directory of Open Access Journals (Sweden)

    Singh Surya Udai

    2009-05-01

    Full Text Available Abstract Background There are no reports describing complications with posterior spinal fusion (PSF with segmental spinal instrumentation (SSI using pedicle screw fixation in patients with neuromuscular scoliosis. Methods Fifty neuromuscular patients (18 cerebral palsy, 18 Duchenne muscular dystrophy, 8 spinal muscular atrophy and 6 others were divided in two groups according to severity of curves; group I ( 90°. All underwent PSF and SSI with pedicle screw fixation. There were no anterior procedures. Perioperative (within three months of surgery and postoperative (after three months of surgery complications were retrospectively reviewed. Results There were fifty (37 perioperative, 13 postoperative complications. Hemo/pneumothorax, pleural effusion, pulmonary edema requiring ICU care, complete spinal cord injury, deep wound infection and death were major complications; while atelectesis, pneumonia, mild pleural effusion, UTI, ileus, vomiting, gastritis, tingling sensation or radiating pain in lower limb, superficial infection and wound dehiscence were minor complications. Regarding perioperative complications, 34(68% patients had at least one major or one minor complication. There were 16 patients with pulmonary, 14 with abdominal, 3 with wound related, 2 with neurological and 1 cardiovascular complications, respectively. There were two deaths, one due to cardiac arrest and other due to hypovolemic shock. Regarding postoperative complications 7 patients had coccygodynia, 3 had screw head prominence, 2 had bed sore and 1 had implant loosening, respectively. There was a significant relationship between age and increased intraoperative blood loss (p = 0.024. However it did not increased complications or need for ICU care. Similarly intraoperative blood loss > 3500 ml, severity of curve or need of pelvic fixation did not increase the complication rate or need for ICU. DMD patients had higher chances of coccygodynia postoperatively. Conclusion

  12. Odontoid balloon kyphoplasty associated with screw fixation for Type II fracture in 2 elderly patients.

    Science.gov (United States)

    Terreaux, Luc; Loubersac, Thomas; Hamel, Olivier; Bord, Eric; Robert, Roger; Buffenoir, Kevin

    2015-03-01

    Anterior screw fixation is a well-recognized technique that is used to stabilize Type IIB fractures of the odontoid process in the elderly. However, advanced age and osteoporosis are 2 risk factors for pseudarthrosis. Kyphoplasty has been described in the treatment of lytic lesions in C-2. The authors decided to combine these 2 techniques in the treatment of unstable fractures of the odontoid. Two approximately 90-year-old patients were treated for this type of fracture. Instability was demonstrated on dynamic radiography in one patient, and the fracture was seen on static radiography in the other. Clinical parameters, pain, range of motion, 36-Item Short Form Health Survey (SF-36) score (for the first patient), and radiological examinations (CT scans and dynamic radiographs) were studied both before and after surgery. After inflating the balloon both above and below the fracture line, the authors applied a high-viscosity polymethylmethacrylate cement. Some minor leakage of cement was noted in both cases but proved to be harmless. The screws were correctly positioned. The clinical result was excellent, both in terms of pain relief and in the fact that there was no reduction in the SF-36 score. The range of motion remained the same. A follow-up CT scan obtained 1 year later in one of the patients showed no evidence of change in the materials used, and the dynamic radiographs showed no instability. This combination of kyphoplasty and anterior screw fixation of the odontoid seems to be an interesting technique in osteoporotic Type IIB fractures of the odontoid process in the elderly, with good results both clinically and radiologically.

  13. The Use of Percutaneous Lumbar Fixation Screws for Bilateral Pedicle Fractures with an Associated Dislocation of a Lumbar Disc Prosthesis

    Directory of Open Access Journals (Sweden)

    William D. Harrison

    2013-01-01

    Full Text Available Study Design. Case report. Objective. To identify a safe technique for salvage surgery following complications of total disc replacement. Summary of Background Data. Lumbar total disc replacement (TDR is considered by some as the gold standard for discogenic back pain. Revision techniques for TDR and their complications are in their infancy. This case describes a successful method of fixation for this complex presentation. Methods and Results. A 48-year-old male with lumbar degenerative disc disease and no comorbidities. Approximately two weeks postoperatively for a TDR, the patient represented with acute severe back pain and the TDR polyethylene inlay was identified as dislocated anteriorly. Subsequent revision surgery failed immediately as the polyethylene inlay redislocated intraoperatively. Further radiology identified bilateral pedicle fractures, previously unseen on the plain films. The salvage fusion of L5/S1 reutilized the anterior approach with an interbody fusion cage and bone graft. The patient was then turned intraoperatively and redraped. The percutaneous pedicle screws were used to fix L5 to the sacral body via the paracoccygeal corridor. Conclusion. The robust locking screw in the percutaneous screw allowed a complete fixation of the pedicle fractures. At 3-year followup, the patient has an excellent result and has returned to playing golf.

  14. Anterior Cruciate Ligament Femoral Socket Drilling With a Retrograde Reamer: Lessons From the Learning Curve

    OpenAIRE

    2013-01-01

    Whereas “anatomic” anterior cruciate ligament reconstruction may improve clinical results, the technique has introduced new technical challenges. The purpose of this technical note and video is to explore tips and tricks that improve femoral socket drilling with a retrograde reamer, bone–patellar tendon–bone graft passage, and interference screw fixation. The techniques for retrograde femoral socket drilling in an inside-out direction, bone–patellar tendon–bone graft passage, and interference...

  15. The Formation of a Pretibial Ganglion Cyst After the Reconstruction of an Anterior Cruciate Ligament

    Energy Technology Data Exchange (ETDEWEB)

    Jang, Seok Jin; Park, Ji Seon; Yoon, Kyung Ho; Park, Yong Goo; Ryu, Kyung Nam [Kyung Hee University Medical Center, Seoul (Korea, Republic of); Park, So Young; Jin, Wook [Kyung Hee University East-West NEO Medical Center, Seoul (Korea, Republic of)

    2010-02-15

    The formation of a pretibial ganglion cyst after the reconstruction of an anterior cruciate ligament is an uncommon complication which may be a result of the degradation of the biodegradable screw or a variety of other reasons. The authors report a case of a significantly large pretibial cyst, which probably occurred as a result of no treatment over a long period, along with a description of the clinical manifestations and radiologic findings

  16. Comparison of Head Center Position and Screw Fixation Options Between a Jumbo Cup and an Offset Center of Rotation Cup in Revision Total Hip Arthroplasty: A Computer Simulation Study.

    Science.gov (United States)

    Faizan, Ahmad; Black, Brandon J; Fay, Brian D; Heffernan, Christopher D; Ries, Michael D

    2016-01-01

    Jumbo acetabular cups are commonly used in revision total hip arthroplasty (THA). A straightforward reaming technique is used which is similar to primary THA. However, jumbo cups may also be associated with hip center elevation, limited screw fixation options, and anterior soft tissue impingement. A partially truncated hemispherical shell was designed with an offset center of rotation, thick superior rim, and beveled anterior and superior rims as an alternative to a conventional jumbo cup. A three dimensional computer simulation was used to assess head center position and safe screw trajectories. Results of this in vitro study indicate that a modified hemispherical implant geometry can reduce head center elevation while permitting favorable screw fixation trajectories into the pelvis in comparison to a conventional jumbo cup.

  17. Anterior avulsion fracture of the tibial tuberosity in adolescents - Two case reports

    Directory of Open Access Journals (Sweden)

    Aleilimar Teixeira da Silva Júnior

    Full Text Available ABSTRACT The objective here was to report two rare cases of anterior avulsion fracture of the tibial tuberosity in adolescents. Case 1 was a 15-year-old male who became injured through landing on his left knee and presented limited extension. Case 2 was a 16-year-old basketball player who presented sudden pain in the right knee and functional incapacity, after a jump. Imaging examinations (radiographs and computed tomography showed anterior avulsion fractures of the tibial tuberosity. Surgical fixation was performed using screws and anchors, while avoiding growth plate injury. The cases evolved without lower-limb deformities.

  18. 下颈椎经椎弓根螺钉内固定相关解剖学观察%Transpedicular screw fixation for the lower cervical spine: anatomical measurement

    Institute of Scientific and Technical Information of China (English)

    解京明; 张漾杰; 鲁宁; 刘宗良; 王迎松; 张颖

    2006-01-01

    [目的]为下颈椎经椎弓根螺钉内固定提供应用解剖学基础及形态学资料.方法 应用游标卡尺和量角器对24具成人颈椎干燥标本C3~7椎弓根的高度、宽度、骨性椎管长度、轴线长度、内外侧皮质厚度及轴线夹角进行解剖学测量,并分别计算各节段左右侧椎弓根测量值的均值和标准差,进行统计学分析.结果 C3~7椎弓根的椎弓根最窄处截面上下皮质骨高度(PH)和松质骨高度(PSH)分别为4.21 mm和7.64 mm,宽度分别为3.64 mm和5.88 mm;轴线长度、骨性椎管长度及侧块部长度分别为15.75 mm、32.20 mm及8.12 mm;最狭窄处内、外侧皮质厚度为0.68mm和1.65 mm;椎弓根轴线与矢状线在水平面上的夹角C3:47.12°±3.05°、C4:43.47°±1.49°、C5:40.15±2.58°、C6:38.55°±2.45°、C7:35.16°±2.10°;椎弓根轴线与水平面间夹角C3:8.50°±2.50°、C4:4.83°±1.65°、C5:1.25°±1.45°、C6:-(4.50°±2.50°)、C7:-(8.50°±2.50°).结论 本实验实体测量数据与国内外数据无显著差异,但发现颈椎椎弓根解剖形态个体变异程度较大,术前必须对置钉椎体进行CT、X线片检查,确定适合个体的进钉点、进钉方向、螺钉直径及长度等.颈椎椎弓根螺钉技术仍然是一种相对安全、固定可靠的手术方法.

  19. Impact of screw elements on continuous granulation with a twin-screw extruder.

    Science.gov (United States)

    Djuric, Dejan; Kleinebudde, Peter

    2008-11-01

    The influence of different screw element types on wet granulation process with a twin-screw extruder was investigated. Lactose granules were prepared with different screw configurations such as conveying, combing mixer and kneading elements. The use of kneading blocks led to an almost complete agglomeration of lactose, whereas kneading and combing mixer elements resulted in smaller granules in comparison. Granule porosity varied between 17.4% and 50.6%. Granule friability values ranged from 1.2% to 38.5%. Conveying elements led to the most porous and friable granules, whereas kneading blocks produced the densest and least friable granules. Combing mixer elements produced granules with median properties. A linear correlation between granule porosity and the natural logarithm of granule friability was detected. Flowability of granules was also influenced by the element type. Compressed granules with higher granule porosities resulted in tablets with higher tensile strength values and vice versa. Twin-screw extruders proved to be a versatile tool for wet granulation. By the choice of a suitable screw element granule and tablet characteristics were influenced.

  20. Analysis of Modeling Parameters on Threaded Screws.

    Energy Technology Data Exchange (ETDEWEB)

    Vigil, Miquela S. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Brake, Matthew Robert [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Vangoethem, Douglas [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2015-06-01

    Assembled mechanical systems often contain a large number of bolted connections. These bolted connections (joints) are integral aspects of the load path for structural dynamics, and, consequently, are paramount for calculating a structure's stiffness and energy dissipation prop- erties. However, analysts have not found the optimal method to model appropriately these bolted joints. The complexity of the screw geometry cause issues when generating a mesh of the model. This paper will explore different approaches to model a screw-substrate connec- tion. Model parameters such as mesh continuity, node alignment, wedge angles, and thread to body element size ratios are examined. The results of this study will give analysts a better understanding of the influences of these parameters and will aide in finding the optimal method to model bolted connections.

  1. Twin screw granulation - review of current progress.

    Science.gov (United States)

    Thompson, M R

    2015-01-01

    Twin screw granulation (TSG) is a new process of interest to the pharmaceutical community that can continuously wet granulate powders, doing so at lower liquid concentrations and with better product consistency than found by a high shear batch mixer. A considerable body of research has evolved over the short time since this process was introduced but generally with little comparison of results. A certain degree of confidence has been developed through these studies related to how process variables and many attributes of machinery configuration will affect granulation but some major challenges still lay ahead related to scalability, variations in the processing regimes related to degree of channel fill and the impact of wetting and granulation of complex powder formulations. This review examines the current literature for wet granulation processes studied in twin screw extrusion machinery, summarizing the influences of operational and system parameters affecting granule properties as well as strives to provide some practical observations to newly interested users of the technique.

  2. MOVING SCREW DISLOCATION IN CUBIC QUASICRYSTAL

    Institute of Scientific and Technical Information of China (English)

    ZHOU Wang-min; SONG Yu-hai

    2005-01-01

    The elasticity theory of the dislocation of cubic quasicrystals is developed.The governing equations of anti-plane elasticity dynamics problem of the quasicrystals were reduced to a solution of wave equations by introducing displacement functions,and the analytical expressions of displacements, stresses and energies induced by a moving screw dislocation in the cubic quasicrystalline and the velocity limit of the dislocation were obtained. These provide important information for studying the plastic deformation of the new solid material.

  3. In vitro evaluation of force-expansion characteristics in a newly designed orthodontic expansion screw compared to conventional screws

    Directory of Open Access Journals (Sweden)

    Oshagh Morteza

    2009-01-01

    Full Text Available Objective : Expansion screws like Hyrax, Haas and other types, produce heavy interrupted forces which are unfavorable for dental movement and could be harmful to the tooth and periodontium. The other disadvantage of these screws is the need for patient cooperation for their regular activation. The purpose of this study was to design a screw and compare its force- expansion curve with other types. Materials and Methods : A new screw was designed and fabricated in the same dimension, with conventional types, with the ability of 8 mm expansion (Free wire length: 12 mm, initial compression: 4.5 mm, spring wire diameter: 0.4 mm, spring diameter: 3 mm, number of the coils: n0 ine, material: s0 tainless steel. In this in vitro study, the new screw was placed in an acrylic orthodontic appliance, and after mounting on a stone cast, the force-expansion curve was evaluated by a compression test machine and compared to other screws. Results : Force-expansion curve of designed screw had a flatter inclination compared to other screws. Generally it produced a light continuous force (two to 3.5 pounds for every 4 mm of expansion. Conclusion : In comparison with heavy and interrupted forces of other screws, the newly designed screw created light and continuous forces.

  4. Research and application of absorbable screw in orthopedics: a clinical review comparing PDLLA screw with metal screw in patients with simple medial malleolus fracture

    Institute of Scientific and Technical Information of China (English)

    TANG Jin; HU Jin-feng; GUO Wei-chun; YU Ling; ZHAO Sheng-hao

    2013-01-01

    Objective:To observe the therapeutic effect of absorbable screw in medial malleolus fracture and discuss its clinical application in orthopedics.Methods:A total of 129 patients with simple medial malleolus fracture were studied.Among them,64 patients were treated with poly-D,L-lactic acid (PDLLA) absorbable screws,while the others were treated with metal screws.All the patients were followed up for 12-20 months (averaged 18.4 months) and the therapeutic effect was evaluated according to the American Orthopaedic Foot and Ankle Society clinical rating systems.Results:In absorbable screw group,we obtained excellent and good results in 62 cases (96.88%); in steel screw group,61 cases (93.85%) achieved excellent and good results.There was no significant difference between the two groups.Conclusion:In the treatment of malleolus fracture,absorbable screw can achieve the same result compared with metal screw fixation.Absorbable screw is preferred due to its advantages of safety,cleanliness and avoiding the removal procedure associated with metallic implants.

  5. Chordal geometry determines the shape and extent of systolic anterior mitral motion: in vitro studies.

    Science.gov (United States)

    Cape, E G; Simons, D; Jimoh, A; Weyman, A E; Yoganathan, A P; Levine, R A

    1989-05-01

    In patients with hypertrophic cardiomyopathy, the mitral valve moves anteriorly and assumes a unique shape, with mitral-septal contact centrally and preserved valve orifice area laterally. This shape is not clearly predicted by the Venturi mechanism, which stresses flow above the valve as opposed to changes intrinsic to the valve. On the other hand, it has been suggested that displacement of the papillary muscles anteriorly and toward one another, as observed in this disease, can promote anterior mitral valve motion and produce this unusual shape. The purpose of this in vitro study was to test the hypotheses that anterior motion of a membrane in a flow field can be generated by altering the distribution or effectiveness of chordal tension tethering the membrane, and that the shape achieved by this membrane depends on the geometry of chordal tension. Accordingly, a horizontal leaflet mounted in a flow chamber was attached by chords at its distal end to a series of upstream screws. Chordal tension could be varied by turning the screws or redirected by shifting the screws anteriorly. Anterior leaflet motion having the same unusual configuration seen in patients was reproduced by decreasing central chordal restraint while tension on the leaflet edges was maintained. Directing chordal tension anteriorly caused greater degrees of anterior motion at earlier stages in the release of chordal restraint; increased flow rate had a similar but less marked effect. These studies suggest that primary geometric alterations in the papillary-mitral apparatus can play an important role in determining the presence and geometry of systolic anterior mitral motion. The nature of these alterations suggests a role for anterior and inward papillary muscle displacement in promoting such motion. The geometric factors embodied in this model can explain many observed features of this motion not adequately explained by the Venturi effect, such as early systolic onset and the importance of a

  6. Double insurance transfacetal screws for lumbar spinal stabilization

    Directory of Open Access Journals (Sweden)

    Atul Goel

    2014-01-01

    Full Text Available Aim: The authors report experience with 14 cases where two screws or ′′double insurance′′ screws were used for transfacetal fixation of each joint for stabilization of the lumbar spinal segment. The anatomical subtleties of the technique of insertion of screws are elaborated. Materials and Methods: During the period March 2011 to June 2014, 14 patients having lumbar spinal segmental instability related to lumbar canal stenosis were treated by insertion of two screws into each articular assembly by transfacetal technique. After a wide surgical exposure, the articular cartilage was denuded and bone chips were impacted into the joint cavity. For screw insertion in an appropriate angulation, the spinous process was sectioned at its base. The screws (2.8 mm in diameter and 18 mm in length were inserted into the substance of the medial or inferior articular facet of the rostral vertebra via the lateral limit of the lamina approximately 6-8 mm away from the edge of the articular cavity. The screws were inserted 3 mm below the superior edge and 5 mm above the inferior edge of the medial (inferior facets and directed laterally and traversed through the articular cavity into the lateral (superior articular facet of the caudal vertebra toward and into the region of junction of base of transverse process and of the pedicle. During the period of follow-up all treated spinal levels showed firm bone fusion. There was no complication related to insertion of the screws. There was no incidence of screw misplacement, displacementor implant rejection. Conclusions: Screw insertion into the firm and largely cortical bones of facets of lumbar spine can provide robust fixation and firm stabilization of the spinal segment. The large size of the facets provides an opportunity to insert two screws at each spinal segment. The firm and cortical bone material and absence on any neural or vascular structure in the course of the screw traverse provides strength and

  7. Finite Element Analysis of Reciprocating Screw for Injection Molding Machine

    Directory of Open Access Journals (Sweden)

    Nagsen B. Nagrale

    2011-06-01

    Full Text Available This paper deals with, the solution of problem occurred for reciprocating screw of Injection molding machine. It identifies and solves the problem by using the modeling and simulation techniques. The problem occurred in the reciprocating screw of machine which was wearing of threads due to affect of temperature of mold materials(flow materials i.e. Nylon, low density polypropylene, polystyrene, PVC etc., The main work was to model the components of machine with dimensions, assemble those components and then simulate the whole assembly for rotation of the screw. The modeling software used is PRO-E wildfire 4.0 for modeling the machine components like body, movable platen, fixed platen, barrel, screw, nozzle, etc. The analysis software ANSYS is used to analyze the reciprocating screws. The objectives involved are:- • To model all the components using modeling software Pro-E 4.0 • To assemble all the components of the machine in the software. • To make the assembly run in Pro-E software.• Analysis of screw of machine using Ansys 11.0 software. • To identify the wearing of threads and to provide the possible solutions.This problem is major for all industrial injection molding machines which the industries are facing and they need the permanent solution, so if the better solution is achieved then the industries will think for implementing it. The industries are having temporary solution but it will affect the life of the screw, because the stresses will be more in machined screw on lathe machine as compared to normal screw. Also if the screw will fail after some years of operation, the new screw available in the market will have the same problem. Also the cost associated with new screw and its mounting is much more as it is the main component of machine.

  8. Economics of water injected air screw compressor systems

    OpenAIRE

    Madhav, K. V.; Kovacevic, A.

    2015-01-01

    There is a growing need for compressed air free of entrained oil to be used in industry. In many cases it can be supplied by oil flooded screw compressors with multi stage filtration systems, or by oil free screw compressors. However, if water injected screw compressors can be made to operate reliably, they could be more efficient and therefore cheaper to operate. Unfortunately, to date, such machines have proved to be insufficiently reliable and not cost effective. This paper describes an in...

  9. Discrete element modelling of screw conveyor-mixers

    Directory of Open Access Journals (Sweden)

    Jovanović Aca

    2015-01-01

    Full Text Available Screw conveyors are used extensively in food, plastics, mineral processing, agriculture and processing industries for elevating and/or transporting bulk materials over short to medium distances. Despite their apparent simplicity in design, the transportation action is very complex for design and constructors have tended to rely heavily on empirical performance data. Screw conveyor performance is affected by its operating conditions (such as: the rotational speed of the screw, the inclination of the screw conveyor, and its volumetric fill level. In this paper, horizontal, several single-pitch screw conveyors with some geometry variations in screw blade was investigated for mixing action during transport, using Discrete Element Method (DEM. The influence of geometry modifications on the performance of screw conveyor was examined, different screw designs were compared, and the effects of geometrical variations on mixing performances during transport were explored. During the transport, the particle tumbles down from the top of the helix to the next free surface and that segment of the path was used for auxiliary mixing action. The particle path is dramatically increased with the addition of three complementary helices oriented in the same direction as screw blades (1458.2 mm compared to 397.6 mm in case of single flight screw conveyor Transport route enlarges to 1764.4 mm, when installing helices oriented in the opposite direction from screw blades. By addition of straight line blade to single flight screw conveyor, the longest particle path is being reached: 2061.6 mm [Projekat Ministarstva nauke Republike Srbije, br. TR-31055

  10. Percutaneous pedicle screw reduction and axial presacral lumbar interbody fusion for treatment of lumbosacral spondylolisthesis: A case series

    Directory of Open Access Journals (Sweden)

    Miller Larry E

    2011-09-01

    Full Text Available Abstract Introduction Traditional surgical management of lumbosacral spondylolisthesis is technically challenging and is associated with significant complications. The advent of minimally invasive surgical techniques offers patients treatment alternatives with lower operative morbidity risk. The combination of percutaneous pedicle screw reduction and an axial presacral approach for lumbosacral discectomy and fusion offers an alternative procedure for the surgical management of low-grade lumbosacral spondylolisthesis. Case presentation Three patients who had L5-S1 grade 2 spondylolisthesis and who presented with axial pain and lumbar radiculopathy were treated with a minimally invasive surgical technique. The patients-a 51-year-old woman and two men (ages 46 and 50-were Caucasian. Under fluoroscopic guidance, spondylolisthesis was reduced with a percutaneous pedicle screw system, resulting in interspace distraction. Then, an axial presacral approach with the AxiaLIF System (TranS1, Inc., Wilmington, NC, USA was used to perform the discectomy and anterior fixation. Once the axial rod was engaged in the L5 vertebral body, further distraction of the spinal interspace was made possible by partially loosening the pedicle screw caps, advancing the AxiaLIF rod to its final position in the vertebrae, and retightening the screw caps. The operative time ranged from 173 to 323 minutes, and blood loss was minimal (50 mL. Indirect foraminal decompression and adequate fixation were achieved in all cases. All patients were ambulatory after surgery and reported relief from pain and resolution of radicular symptoms. No perioperative complications were reported, and patients were discharged in two to three days. Fusion was demonstrated radiographically in all patients at one-year follow-up. Conclusions Percutaneous pedicle screw reduction combined with axial presacral lumbar interbody fusion offers a promising and minimally invasive alternative for the management

  11. New parameters to represent the position of the aorta relative to the spine for pedicle screw placement.

    Science.gov (United States)

    Takeshita, Katsushi; Maruyama, Toru; Ono, Takashi; Ogihara, Satoshi; Chikuda, Hirotaka; Shoda, Naoki; Nakao, Yusuke; Matsudaira, Ko; Seichi, Atsushi; Nakamura, Kozo

    2010-05-01

    Parameters of the position of the aorta in previous reports were determined for anterior surgery. This study evaluated the relative position of the aorta to the spine by new parameters, which could enhance the safety of pedicle screw placement. Three parameters were defined in a new Cartesian coordinate system. We selected an entry point of a left pedicle screw as the origin. The transverse plane was determined to include both the bases of the superior facet and to be parallel to the upper endplate of the vertebral body. A line connecting the entry points of both sides was defined as the X-axis. The angle formed by the Y-axis and a line connecting the origin and the center of the aorta was defined as the left pedicle-aorta angle. The length of a line connecting the origin and the aorta edge was defined as the left pedicle-aorta distance. Distance from the edge of the aorta to the X-axis was defined as the pedicular line-aorta distance. These parameters were measured preoperatively in 293 vertebral bodies of 24 patients with a right thoracic curve. We simulated the placement of the pedicle screw with variable length and with some direction error. We defined a warning pedicle as that when the aorta enters the expected area of the screw. Sensitivity analysis was performed to find the warning pedicle ratio in 12 scenarios. The left pedicle-aorta angle averaged 29.7 degrees at the thoracic spine and -16.3 degrees at the lumbar spine; the left pedicle-aorta distance averaged 23.7 and 55.2 mm; the pedicular line-aorta distance averaged 18.3 and 51.0 mm, respectively. The ratio of warning pedicles was consistently high at T4-5 and T10-12. When a left pedicle screw perforates an anterior/lateral wall of the vertebral body, the aorta may be at risk. These new parameters enable surgeons to intuitively understand the position of the aorta in surgical planning or in placement of a pedicle screw.

  12. The transpedicular corpectomy through simple posterior approach combined with internal fixation and prosthetic vertebral replacement for thoracic and lumbar spine metastatic tumor%单纯后路经椎弓根椎体次全切除内固定联合人工椎体置换治疗胸腰椎转移瘤

    Institute of Scientific and Technical Information of China (English)

    燕太强; 郭卫; 杨荣利; 董森; 李晓

    2011-01-01

    Objective To evaluate the clinical outcome of the transpedicular corpectomy through simple posterior approach combined with intemal fixation and prosthetic vertebral replacement for thoracic and lumbar spine metastatic tumor.Methods From January 2007 to March 2010, 21 patients with thoracic and lumbar spine metastatic tumors (9 males, 12 females; 16 in thoracic spine, 5 in lumbar spine) underwent the transpedicular corpectomy through simple posterior approach combined with internal fixation and prosthetic vertebral replacement.The mean age was 58 years (range, 39-77 years).The average pre-operative VAS score was 7.4 (range, 5-10).According to the pre-operative Frankel grades for spinal cord, 3 cases obtained grade C, 6 grade D and 12 grade E.Pre-operative ECOG grades showed 1 case with grade 2, 18 with grade 3 and 2 with grade 4.Results The mean operative time was 3.5 hours (range, 2-5 hours), with no intra-operative death.The mean intra-operative blood loss was 2150 ml (range, 800-5000ml).1 patient died of multiple organ failure two weeks postoperatively.A11 patients with pain reported lower VAS scores postoperatively (with average being 3.1; range, 1-4.5).Of the Frankel grades, 1 patient with grade C reported no change after surgery, while 1 patient with grade C was improved to grade D and 6 patients with grade D to grade E.3 cases (14.3%)were re-operated half year to 1 year after surgery due to recurrence.In the last follow-up, 20 patients had already been followed up for an average of 13 months (range, 3-24months).Among them, 13 cases died of the primary disease with an average survival of 10 months.The remaining surviving patients reported ECOG grades from grade 1 to grade 3.Conclusions The transpedicular corpectomy through simple posterior approach combined with internal fixation and prosthetic vertebral replacement for thoracic and lumbar spine metastatic tumor can provide plentiful decompression and achieve favorable surgical results.It can effectively

  13. Fluid Flow Phenomenon in a Three-Bladed Power-Generating Archimedes Screw Turbine

    OpenAIRE

    2016-01-01

    Experimental studies of the Archimedes screw turbine are applied as a micro hydro power plant for low head focused on the fluid flow. Fluid flow on a screw turbine is not completely filled water flow there is still a free surface between the water fluid and atmospheric air. Except the screw geometry, the turbine screw free surface allows the flow phenomena that are important in the process of turbine screw power generation. The Archimedes screw turbine main driving force is the fl...

  14. Wet granulation in a twin-screw extruder: implications of screw design.

    Science.gov (United States)

    Thompson, M R; Sun, J

    2010-04-01

    Wet granulation in twin-screw extrusion machinery is an attractive technology for the continuous processing of pharmaceuticals. The performance of this machinery is integrally tied to its screw design yet little fundamental knowledge exists in this emerging field for granulation to intelligently create, troubleshoot, and scale-up such processes. This study endeavored to systematically examine the influence of different commercially available screw elements on the flow behavior and granulation mechanics of lactose monohydrate saturated at low concentration (5-12%, w/w) with an aqueous polyvinyl-pyrrolidone binder. The results of the work showed that current screw elements could be successfully incorporated into designs for wet granulation, to tailor the particle size as well as particle shape of an agglomerate product. Conveying elements for cohesive granular flows were shown to perform similar to their use in polymer processing, as effective transport units with low specific mechanical energy input. The conveying zones provided little significant change to the particle size or shape, though the degree of channel fill in these sections had a significant influence on the more energy-intensive mixing elements studied. The standard mixing elements for this machine, kneading blocks and comb mixers, were found to be effective for generating coarser particles, though their mechanisms of granulation differed significantly.

  15. Anterior crucate ligament (ACL) injury

    Science.gov (United States)

    ... An anterior cruciate ligament injury is the over-stretching or tearing of the anterior cruciate ligament (ACL) ... may be injured. This is a medical emergency. Prevention Use proper techniques when playing sports or exercising. ...

  16. Comparison between Bilateral C2 Pedicle Screwing and Unilateral C2 Pedicle Screwing, Combined with Contralateral C2 Laminar Screwing, for Atlantoaxial Posterior Fixation

    OpenAIRE

    Miyakoshi, Naohisa; HONGO, MICHIO; Kobayashi, Takashi; Suzuki, Tetsuya; Abe, Eiji; Shimada, Yoichi

    2014-01-01

    Study Design A retrospective study. Purpose To compare clinical and radiological outcomes between bilateral C2 pedicle screwing (C2PS) and unilateral C2PS, combined with contralateral C2 laminar screwing (LS), for posterior atlantoaxial fixation. Overview of Literature Posterior fixation with C1 lateral mass screwing (C1LMS) and C2PS (C1LMS-C2PS method) is an accepted procedure for rigid atlantoaxial stabilization. However, conventional bilateral C2PS is not always allowed in this method due ...

  17. Reliability of predictors for screw cutout in intertrochanteric hip fractures

    NARCIS (Netherlands)

    K.M.J. de Bruijn (Kirstin); D. den Hartog (Dennis); W.E. Tuinebreijer (Wim); G.R. Roukema (Gert)

    2012-01-01

    textabstractBackground: Following internal fixation of intertrochanteric hip fractures, tip apex distance, fracture classification, position of the screw in the femoral head, and fracture reduction are known predictors for screw cutout, but the reliability of these measurements is unknown. We invest

  18. Intermaxillary Fixation Screw Morbidity in Treatment of Mandibular Fractures

    DEFF Research Database (Denmark)

    Florescu, Vlad-Andrei; Kofod, Thomas; Pinholt, Else Marie

    2016-01-01

    PURPOSE: The aim of the present retrospective study was to investigate the morbidity of screws used for intermaxillary fixation (IMF) in the treatment of mandibular fractures. A review of the published data was also performed for a comparison of outcomes. Our hypothesis was that the use of screws...

  19. KINEMATICS OF 3-DOF PYRAMID MANIPULATOR BY PRINCIPAL SCREWS

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Kinematics of a 3-RPS parallel pyramid manipulator are investigated by principal screw. Firstly, the principal screws are identified by quadric degeneration. The planar conics representing the relations between the pitches and the three linear inputs are described, and the three-dimensional distribution of the axes of all the twists is illustrated. Finally, a numerical example is given successfully.

  20. [Loosening of a Calcaneo-Stop Screw after Trampolining].

    Science.gov (United States)

    Trieb, K; Fingernagel, T; Petershofer, A; Hofstaetter, S G

    2015-06-01

    Flexible flatfoot is a common malalignment in the paediatric population. Arthroereisis with a calcaneo-stop screw is an effective surgical procedure for treating juvenile flexible flatfoot after conservative measures have been fully exploited. In the present report, we describe the case of a loosening of a calcaneo-stop screw in a 12-year-old youth after excessive trampolining.

  1. Determination of the of rate cross slip of screw dislocations

    DEFF Research Database (Denmark)

    Vegge, Tejs; Rasmussen, Torben; Leffers, Torben;

    2000-01-01

    The rate for cross slip of screw dislocations during annihilation of screw dipoles in copper is determined by molecular dynamics simulations. The temperature dependence of the rate is seen to obey an Arrhenius behavior in the investigated temperature range: 225-375 K. The activation energy...

  2. Facetas em dentes anteriores

    OpenAIRE

    Veloso, Helena Rafaela Lourenço Martins

    2015-01-01

    Projeto de Pós-Graduação/Dissertação apresentado à Universidade Fernando Pessoa como parte dos requisitos para obtenção do grau de Mestre em Medicina Dentária A presente revisão bibliográfica aborda as facetas estéticas em dentes anteriores, pela crescente valorização de um sorriso esteticamente agradável, facto que faz com que as pessoas procurem cada vez mais alternativas de tratamento para melhorar a aparência do seu sorriso. Os dentes anteriores são decisivos na aparência estética e, c...

  3. Intradural anterior transpetrosal approach.

    Science.gov (United States)

    Ichimura, Shinya; Hori, Satoshi; Hecht, Nils; Czabanka, Marcus; Vajkoczy, Peter

    2016-10-01

    The standard anterior transpetrosal approach (ATPA) for petroclival lesions is fundamentally an epidural approach and has been practiced for many decades quite successfully. However, this approach has some disadvantages, such as epidural venous bleeding around foramen ovale. We describe here our experience with a modified technique for anterior petrosectomy via an intradural approach that overcomes these disadvantages. Five patients with petroclival lesions underwent surgery via the intradural ATPA. The intraoperative hallmarks are detailed, and surgical results are reported. Total removal of the lesions was achieved in two patients with petroclival meningioma and two patients with pontine cavernoma, whereas subtotal removal was achieved in one patient with petroclival meningioma without significant morbidity. No patient experienced cerebrospinal fluid leakage. The intradural approach is allowed to tailor the extent of anterior petrosectomy to the individually required exposure, and the surgical procedure appeared to be more straightforward than via the epidural route. Caveats encountered with the approach were the temporal basal veins that could be spared as well as identification of the petrous apex due to the lack of familial epidural landmarks. The risk of injury to the temporal bridging veins is higher in this approach than in the epidural approach. Intradural approach is recommended in patients with a large epidural venous route, such as sphenobasal and sphenopetrosal vein. Navigation via bone-window computed tomography is useful to identify the petrous apex.

  4. A four lumen screwing device for multiparametric brain monitoring.

    Science.gov (United States)

    Feuerstein, T H; Langemann, H; Gratzl, O; Mendelowitsch, A

    2000-01-01

    We describe multiparametric monitoring in severe head trauma using a new screwing device. Our aim was to create a screw which would make the implantation of the probes and thus multiparametric monitoring easier. The new screw allows us to implant 3 probes (microdialysis, Paratrend and an intracranial pressure device) through one burr hole. The screw has four channels, the fourth being for ventricular drainage. We monitored 13 patients with severe head trauma (GCS = 3-8) for up to 7 days. Brain tissue pO2, pCO2, pH, and temperature were measured on-line with the Paratrend 7 machine. The microdialytic parameters glucose, lactate, pyruvate and glutamate were determined semi on-line with a CMA 600 enzymatic analyser. There were no complications in any of the patients that could be ascribed to the screw.

  5. On Helical Projection and Its Application in Screw Modeling

    Directory of Open Access Journals (Sweden)

    Riliang Liu

    2014-04-01

    Full Text Available As helical surfaces, in their many and varied forms, are finding more and more applications in engineering, new approaches to their efficient design and manufacture are desired. To that end, the helical projection method that uses curvilinear projection lines to map a space object to a plane is examined in this paper, focusing on its mathematical model and characteristics in terms of graphical representation of helical objects. A number of interesting projective properties are identified in regard to straight lines, curves, and planes, and then the method is further investigated with respect to screws. The result shows that the helical projection of a cylindrical screw turns out to be a Jordan curve, which is determined by the screw's axial profile and number of flights. Based on the projection theory, a practical approach to the modeling of screws and helical surfaces is proposed and illustrated with examples, and its possible application in screw manufacturing is discussed.

  6. The Analysis of Soil Resistance During Screw Displacement Pile Installation

    Directory of Open Access Journals (Sweden)

    Krasinski Adam

    2015-02-01

    Full Text Available The application of screw displacement piles (SDP is still increasing due to their high efficiency and many advantages. However, one technological problem is a serious disadvantage of those piles. It relates to the generation of very high soil resistance during screw auger penetration, especially when piles are installed in non-cohesive soils. In many situations this problem causes difficulties in creating piles of designed length and diameter. It is necessary to find a proper method for prediction of soil resistance during screw pile installation. The analysis of screw resistances based on model and field tests is presented in the paper. The investigations were carried out as part of research project, financed by the Polish Ministry of Science and Higher Education. As a result of tests and analyses the empirical method for prediction of rotation resistance (torque during screw auger penetration in non-cohesive subsoil based on CPT is proposed.

  7. The Analysis of Soil Resistance During Screw Displacement Pile Installation

    Science.gov (United States)

    Krasinski, Adam

    2015-02-01

    The application of screw displacement piles (SDP) is still increasing due to their high efficiency and many advantages. However, one technological problem is a serious disadvantage of those piles. It relates to the generation of very high soil resistance during screw auger penetration, especially when piles are installed in non-cohesive soils. In many situations this problem causes difficulties in creating piles of designed length and diameter. It is necessary to find a proper method for prediction of soil resistance during screw pile installation. The analysis of screw resistances based on model and field tests is presented in the paper. The investigations were carried out as part of research project, financed by the Polish Ministry of Science and Higher Education. As a result of tests and analyses the empirical method for prediction of rotation resistance (torque) during screw auger penetration in non-cohesive subsoil based on CPT is proposed.

  8. Lumbar pedicle cortical bone trajectory screw

    Institute of Scientific and Technical Information of China (English)

    Song Tengfei; Wellington K Hsu; Ye Tianwen

    2014-01-01

    Objective The purpose of this study was to demonstrate the lumbar pedicle cortical bone trajectory (CBT) screw fixation technique,a new fixation technique for lumbar surgery.Data sources The data analyzed in this review are mainly from articles reported in PubMed published from 1994 to 2014.Study selection Original articles and critical reviews relevant to CBT technique and lumbar pedicle fixation were selected.Results CBT technique was firstly introduced as a new fixation method for lumbar pedicle surgery in 2009.The concepts,morphometric study,biomechanical characteristics and clinical applications of CBT technique were reviewed.The insertional point of CBT screw is located at the lateral point of the pars interarticularis,and its trajectory follows a caudocephalad path sagittally and a laterally directed path in the transverse plane.CBT technique can be used for posterior fixation during lumbar fusion procedures.This technique is a minimally invasive surgery,which affords better biomechanical stability,fixation strength and surgical safety.Therefore,CBT technique has the greatest benefit in lumbar pedicle surgery for patients with osteoporosis and obesity.Conclusion CBT technique is a better alternative option of lumbar pedicle fixation,especially for patients with osteoporosis and obesity.

  9. Asymmetric distribution in twin screw granulation.

    Science.gov (United States)

    Chan Seem, Tim; Rowson, Neil A; Gabbott, Ian; de Matas, Marcel; Reynolds, Gavin K; Ingram, Andy

    2016-09-01

    Positron Emission Particle Tracking (PEPT) was successfully employed to validate measured transverse asymmetry in material distribution in the conveying zones of a Twin Screw Granulator (TSG). Flow asymmetry was established to be a property of the granulator geometry and dependent on fill level. The liquid distribution of granules as a function of fill level was determined. High flow asymmetry at low fill level negatively affects granule nucleation leading to high variance in final uniformity. Wetting of material during nucleation was identified as a critical parameter in determining final granule uniformity and fill level is highlighted as a crucial control factor in achieving this. Flow asymmetry of dry material in conveying zones upstream of binder fluid injection leads to poor non-uniform wetting at nucleation and results in heterogeneous final product. The granule formation mechanism of 60°F kneading blocks is suggested to be primarily breakage of agglomerates formed during nucleation. Optimisation of screw configuration would be required to provide secondary growth. This work shows how fill dependent flow regimes affect granulation mechanisms.

  10. Supermassive screwed cosmic string in dilaton gravity

    Energy Technology Data Exchange (ETDEWEB)

    Bezerra, V B [Departamento de Fisica, Universidade Federal da ParaIba, 58059-970, Joao Pessoa, PB (Brazil); Ferreira, Cristine N [Nucleo de Fisica, Centro Federal de Educacao Tecnologica de Campos, Rua Dr Siqueira, 273-Parque Dom Bosco, 28030-130, Campos dos Goytacazes, RJ (Brazil); Cuesta, H J Mosquera [Instituto de Cosmologia, Relatividade e AstrofIsica (ICRA-BR), Centro Brasileiro de Pesquisas Fisicas, Rua Dr Xavier Sigaud 150, Urca 22290-180, Rio de Janeiro, RJ (Brazil)

    2006-06-21

    The early universe might have undergone phase transitions at energy scales much higher than the one corresponding to the grand unified theories (GUT) scales. At these higher energy scales, the transition at which gravity separated from all other interactions, the so-called Planck era, more massive strings called supermassive cosmic strings could have been produced, with energy of about 10{sup 19} GeV. The dynamics of strings formed with this energy scale cannot be described by means of the weak-field approximation, as in the standard procedure for ordinary GUT cosmic strings. As suggested by string theories, at this extreme energy, gravity may be transmitted by some kind of scalar field (usually called the dilaton) in addition to the tensor field of Einstein's theory of gravity. It is then permissible to tackle the issue regarding the dynamics of supermassive cosmic strings within this framework. With this aim, we obtain the gravitational field of a supermassive screwed cosmic string in a scalar-tensor theory of gravity. We show that for the supermassive configuration, exact solutions of scalar-tensor screwed cosmic strings can be found in connection with the Bogomol'nyi limit. We show that the generalization of Bogomol'nyi arguments to the Brans-Dicke theory is possible when torsion is present and we obtain an exact solution in this supermassive regime, with the dilaton solution obtained by consistency with internal constraints.

  11. Comparison of therapeutic effect between percutaneous kyphoplasty and pedicle screw system on vertebral compression fracture

    Institute of Scientific and Technical Information of China (English)

    MING Jiang-hua; ZHOU Jian-lin; ZHOU Pang-hu; ZHOU Jian-peng

    2007-01-01

    Objective:To compare the clinical efficacy of percutaneous kyphoplasty (PKP) with pedicle screw system(PS) in the treatment of vertebral compression fracture(VCF). Methods:Eighty-six patients with VCF were treated either by PKP (Group A,n = 30) ) or PS ( Group B,n =56).The anterior,intermediate,and posterior heights of the vertebrae body,visual analogue pain scale(VAS) before and after operation,the duration of operation,and amount of blood loss between two groups were compared. Results:No statistical difference was noted regarding the vertebral height between two groups. Significant difference was seen in VAS,duration of operation and amount of blood loss between the two groups ( P < 0.01). Conclusions:Percutaneous kyphoplasty has the similar therapeutic efficacy with pedicle screw system in treatment of VCF with a minimal invasion,less operation time and blood loss. For those with posterior wall destruction,PS is deemed favorable.

  12. 3D Printing Surgical Implants at the clinic: A Experimental Study on Anterior Cruciate Ligament Reconstruction.

    Science.gov (United States)

    Liu, An; Xue, Guang-huai; Sun, Miao; Shao, Hui-feng; Ma, Chi-yuan; Gao, Qing; Gou, Zhong-ru; Yan, Shi-gui; Liu, Yan-ming; He, Yong

    2016-02-15

    Desktop three-dimensional (3D) printers (D3DPs) have become a popular tool for fabricating personalized consumer products, favored for low cost, easy operation, and other advantageous qualities. This study focused on the potential for using D3DPs to successfully, rapidly, and economically print customized implants at medical clinics. An experiment was conducted on a D3DP-printed anterior cruciate ligament surgical implant using a rabbit model. A well-defined, orthogonal, porous PLA screw-like scaffold was printed, then coated with hydroxyapatite (HA) to improve its osteoconductivity. As an internal fixation as well as an ideal cell delivery system, the osteogenic scaffold loaded with mesenchymal stem cells (MSCs) were evaluated through both in vitro and in vivo tests to observe bone-ligament healing via cell therapy. The MSCs suspended in Pluronic F-127 hydrogel on PLA/HA screw-like scaffold showed the highest cell proliferation and osteogenesis in vitro. In vivo assessment of rabbit anterior cruciate ligament models for 4 and 12 weeks showed that the PLA/HA screw-like scaffold loaded with MSCs suspended in Pluronic F-127 hydrogel exhibited significant bone ingrowth and bone-graft interface formation within the bone tunnel. Overall, the results of this study demonstrate that fabricating surgical implants at the clinic (fab@clinic) with D3DPs can be feasible, effective, and economical.

  13. Valgus osteotomy of the tibia with a Puddu plate combined with anterior cruciate ligament reconstruction

    Directory of Open Access Journals (Sweden)

    Albuquerque Roberto Freire da Mota e

    2003-01-01

    Full Text Available Anterior knee instability associated with a varus deformity is a complex condition with several treatment possibilities. Among these, anterior cruciate ligament (ACL associated to a simultaneous valgus tibial osteotomy is a increasing indication. This simultaneous procedure adds technical issues to those related to the isolated surgeries. Thus, the osteotomy plane and location of fixation hardware shouldn?t conflict with tibial tunnel and ACL graft fixation. Authors analyze the relations between a opening tibial valgus osteotomy stabilized with a Puddu plate and ACL reconstruction with a patellar tendon graft fixated with interference screws in 10 human cadaver knees. A straight oblique tibial osteotomy starting on the medial tibial cortex and oriented laterally and proximally was performed on all knees with a 10mm opening medially and stabilized with a Puddu plate on the most posterior aspect of the medial tibia, and a tibial tunnel drilled 50° to tibial plateau. With this technique there was no intersection between tibial tunnel or interference screw and the osteotomy or the plate fixation screws.

  14. Optimization of Twin-Screw Superchargers for Combined Compressor - Expander Performance (SCREW); Optimierung von Schraubenladern fuer den kombinierten Verdichtungs- und Expansionsbetrieb (SCREW)

    Energy Technology Data Exchange (ETDEWEB)

    Romba, M. [Dortmund Univ. (Germany). Fachgebiet Fluidenergiemaschinen

    2005-07-01

    During the last years the use of mechanical superchargers has gained increasing interest in a bid to combine attractive emission- and fuel consumption values with dynamic driving performance. Based on an analysis of available supercharging systems the development potential of twin screw superchargers is assessed. A concept using inlet slide valves is developed which allows at the same time to control the mass flow delivered by the supercharger and achieve an expansion of the transported charge under part load conditions when the delivered pressure is lower than ambient pressure, achieving a reduction in necessary shaft power or even the delivery of shaft power. To distinguish it from conventional superchargers the new device is called ''SCREW'' - screw type machine with compressor respectively expander working mode. The effect of several design parameters on the SCREW'S performance is evaluated by extensive simulation calculations, showing that a suitable design varies considerably from conventional supercharger designs and that a significant amount of further research, especially covering the development of rotor profiles suited for the specific task, is still needed to fully utilize the concept's potential. As a proof of concept prototype SCREW'S, based on a conventional twin screw supercharger, have been built and tested. The results obtained made clear the general suitability of the concept but also underlined the shortcomings of the prototype as they had already been predicted by the simulations. (orig.)

  15. Immediate loading of titanium hexed screw-type implants in the edentulous patient: case report.

    Science.gov (United States)

    Calvo, M P; Muller, E; Garg, A K

    2000-01-01

    Histologic and histomorphometric studies in both animals and humans have shown that more rapid and greater bone-to-implant contact can be achieved with implants that incorporate certain surface characteristics compared with the original machined-surface implants. Such findings are significant because various implant designs may allow the fixtures to sufficiently resist functional loading sooner than originally thought. The case report presented here indicates that immediate loading of hexed titanium screw-type implants in the anterior mandible can lead to successful osseointegration and clinical outcome. The number of implants placed, their distribution, and the type of rigid connection are critical considerations for immediate loading. A bone height that can accommodate dental implants > or = 10 mm long is recommended. Biomechanically, the implants to be immediately loaded must be stable and resistant to macromovement to ensure good osseointegration.

  16. FUNCTIONAL OUTCOME OF ARTHROSCOPY ASSISTED ANTERIOR CRUCIATE LIGAMENT RECONSTRUCTION USING BONE PATELLAR TENDON BONE AUTOGRAFT

    Directory of Open Access Journals (Sweden)

    Vinod Kumar

    2015-04-01

    Full Text Available INTRODUCTION: The anterior cruciate ligament (ACL is one of the most frequently injured ligaments in the human body. 1 The Anterior Cruciate ligament (ACL is the primary stabilizer of the knee and prevents the knee against anterior translation. 2 It is also important in counteracting rotational and valgus stress. 1 The middle third of the patellar tendon autograft for ACL reconstruction can be readily procured and firmly fixed. 3 It can tolerate the loads produced by an intensive rehabilitation programme. 3 Fixation of bone plugs using interference screws provides sufficient stability to meet the demand of a vigorous postoperative protocol. 3 It remains the gold standard for ACL reconstruction. 3 This study is to assess the functional outcome of arthroscopy assisted anterior cruciate ligament reconstruction using bone patellar tendon bone autograft. METHODS: This study was conducted in Kempegowda Institute of Medical Sciences Hospital from November 2012 to April 2014. During this period 20 cases of adult patients with ACL deficient patients were selected according to the inclusion criteria. Study aims to assess the functional outcome of arthroscopy assisted anterior cruciate ligament reconstruction using bone - patellar tendon - bone autograft in terms of range of motion, postoperative knee stability, graft site morbidity and subjective knee functions. RESULTS: Results of our study showed that arthroscopy assisted anterior cruciate ligament reconstruction with bone - patellar tendon - bone autograft could effectively improve knee stability and functions after surgery without any complication. CONCLUSION : Arthroscopy assisted anterior cruciate l igament reconstruction with bone - patellar tendon - bone autograft is an excellent treatment option for anterior cruciate ligament deficient knees. It provides a stable knee and reduces postoperative morbidity and enables early rehabilitation. The functional outcome of arthroscopy assisted anterior

  17. Anterior knee pain

    Energy Technology Data Exchange (ETDEWEB)

    LLopis, Eva [Hospital de la Ribera, Alzira, Valencia (Spain) and Carretera de Corbera km 1, 46600 Alzira Valencia (Spain)]. E-mail: ellopis@hospital-ribera.com; Padron, Mario [Clinica Cemtro, Ventisquero de la Condesa no. 42, 28035 Madrid (Spain)]. E-mail: mario.padron@clinicacemtro.com

    2007-04-15

    Anterior knee pain is a common complain in all ages athletes. It may be caused by a large variety of injuries. There is a continuum of diagnoses and most of the disorders are closely related. Repeated minor trauma and overuse play an important role for the development of lesions in Hoffa's pad, extensor mechanism, lateral and medial restrain structures or cartilage surface, however usually an increase or change of activity is referred. Although the direct relation of cartilage lesions, especially chondral, and pain is a subject of debate these lesions may be responsible of early osteoarthrosis and can determine athlete's prognosis. The anatomy and biomechanics of patellofemoral joint is complex and symptoms are often unspecific. Transient patellar dislocation has MR distinct features that provide evidence of prior dislocation and rules our complication. However, anterior knee pain more often is related to overuse and repeated minor trauma. Patella and quadriceps tendon have been also implicated in anterior knee pain, as well as lateral or medial restraint structures and Hoffa's pad. US and MR are excellent tools for the diagnosis of superficial tendons, the advantage of MR is that permits to rule out other sources of intraarticular derangements. Due to the complex anatomy and biomechanic of patellofemoral joint maltracking is not fully understood; plain films and CT allow the study of malalignment, new CT and MR kinematic studies have promising results but further studies are needed. Our purpose here is to describe how imaging techniques can be helpful in precisely defining the origin of the patient's complaint and thus improve understanding and management of these injuries.

  18. The anterior cingulate cortex

    Directory of Open Access Journals (Sweden)

    Pavlović D.M.

    2009-01-01

    Full Text Available The anterior cingulate cortex (ACC has a role in attention, analysis of sensory information, error recognition, problem solving, detection of novelty, behavior, emotions, social relations, cognitive control, and regulation of visceral functions. This area is active whenever the individual feels some emotions, solves a problem, or analyzes the pros and cons of an action (if it is a right decision. Analogous areas are also found in higher mammals, especially whales, and they contain spindle neurons that enable complex social interactions. Disturbance of ACC activity is found in dementias, schizophrenia, depression, the obsessive-compulsive syndrome, and other neuropsychiatric diseases.

  19. Engineering Aspects of Single- and Twin-screw Extrusion-cooking of Biopolymers

    NARCIS (Netherlands)

    Zuilichem, D.J. van; Stolp, W.; Janssen, L.P.B.M.

    1983-01-01

    A survey is given of the properties of single- and twin-screw extruders. The influence on the design of the different leakage gaps existing in co-rotating, counter-rotating, self-wiping, twin-screw extruders and single-screw equipment is discussed. The mixing effects in single- and twin-screw equipm

  20. Economics of water injected air screw compressor systems

    Science.gov (United States)

    Venu Madhav, K.; Kovačević, A.

    2015-08-01

    There is a growing need for compressed air free of entrained oil to be used in industry. In many cases it can be supplied by oil flooded screw compressors with multi stage filtration systems, or by oil free screw compressors. However, if water injected screw compressors can be made to operate reliably, they could be more efficient and therefore cheaper to operate. Unfortunately, to date, such machines have proved to be insufficiently reliable and not cost effective. This paper describes an investigation carried out to determine the current limitations of water injected screw compressor systems and how these could be overcome in the 15-315 kW power range and delivery pressures of 6-10 bar. Modern rotor profiles and approach to sealing and cooling allow reasonably inexpensive air end design. The prototype of the water injected screw compressor air system was built and tested for performance and reliability. The water injected compressor system was compared with the oil injected and oil free compressor systems of the equivalent size including the economic analysis based on the lifecycle costs. Based on the obtained results, it was concluded that water injected screw compressor systems could be designed to deliver clean air free of oil contamination with a better user value proposition than the oil injected or oil free screw compressor systems over the considered range of operations.

  1. Positioning of pedicle screws in adolescent idiopathic scoliosis using electromyography

    Directory of Open Access Journals (Sweden)

    Bruno Moreira Gavassi

    2015-06-01

    Full Text Available OBJECTIVE: To analyze the occurrence of poor positioning of pedicle screws inserted with the aid of intraoperative electromyographic stimulation in the treatment of Adolescent Idiopathic Scoliosis (AIS.METHODS: This is a prospective observational study including all patients undergoing surgical treatment for AIS, between March and December 2013 at a single institution. All procedures were monitored by electromyography of the inserted pedicle screws. The position of the screws was evaluated by assessment of postoperative CT and classified according to the specific AIS classification system.RESULTS: Sixteen patients were included in the study, totalizing 281 instrumented pedicles (17.5 per patient. No patient had any neurological deficit or complaint after surgery. In the axial plane, 195 screws were found in ideal position (69.4% while in the sagittal plane, 226 screws were found in ideal position (80.4%. Considering both the axial and the sagittal planes, it was observed that 59.1% (166/281 of the screws did not violate any cortical wall.CONCLUSION: The use of pedicle screws proved to be a safe technique without causing neurological damage in AIS surgeries, even with the occurrence of poor positioning of some implants.

  2. Preliminary Design on Screw Press Model of Palm Oil Extraction Machine

    Science.gov (United States)

    Firdaus, Muhammad; Salleh, S. M.; Nawi, I.; Ngali, Z.; Siswanto, W. A.; Yusup, E. M.

    2017-01-01

    The concept of the screw press is to compress the fruit bunch between the main screw and travelling cones to extract the palm oil. Visual inspection, model development and simulation of screw press by using Solidworks 2016 and calculation of design properties were performed to support the investigation. The project aims to analyse different design of screw press which improves in reducing maintenance cost and increasing lifespan. The currently existing of screw press can endure between 500 to 900 hours and requires frequent maintenance. Different configurations have been tried in determination of best design properties in screw press. The results specify that screw press with tapered inner shaft has more total lifespan (hours) compared existing screw press. The selection of the screw press with tapered inner shaft can reduce maintenance cost and increase lifespan of the screw press.

  3. Simulation and analysis of resin flow in injection machine screw

    Institute of Scientific and Technical Information of China (English)

    Ling-feng LI; Samir MEKID

    2008-01-01

    A method with simulation and analysis of the resin flow in a screw is presented to ease the control of some problems that may affect the efficiency and the quality of the product among existing screws in an injection machine. The physical model of a screw is established to represent the stress, the strain, the relationship between velocity and stress, and the temperature of the cells. In this paper, a working case is considered where the velocity and the temperature distributions at any section of the flow are obtained. The analysis of the computational results shows an ability to master various parameters depending on the specifications.

  4. Noninvasive method for retrieval of broken dental implant abutment screw

    Directory of Open Access Journals (Sweden)

    Jagadish Reddy Gooty

    2014-01-01

    Full Text Available Dental implants made of titanium for replacement of missing teeth are widely used because of ease of technical procedure and high success rate, but are not free of complications and may fail. Fracturing of the prosthetic screw continues to be a problem in restorative practice and great challenge to remove the fractured screw conservatively. This case report describes and demonstrates the technique of using an ultrasonic scaler in the removal of the fracture screw fragment as a noninvasive method without damaging the hex of implants.

  5. Electromagnetic Lead Screw for Potential Wave Energy Application

    DEFF Research Database (Denmark)

    Lu, Kaiyuan; Wu, Weimin

    2014-01-01

    This paper presents a new type electromagnetic lead screw (EMLS) intended for wave energy application. Similar to the mechanical lead screw, this electromagnetic version can transfer slow linear motion to high-rotational motion, offering gearing effects. Compared with the existing pure magnetic...... lead screw (MLS) employing permanent magnets only, the new EMLS proposed uses dc current to provide the required helical-shape magnetic field, offering a much simpler, robust structure compared with the MLS. The working principle and the performances of this EMLS are analyzed in this paper. Comparison...

  6. 3D CFD analysis of a twin screw expander

    OpenAIRE

    Kovacevic, A.; S Rane

    2013-01-01

    Twin screw machines can be used as expanders for variety of applications. This paper describes how the performance of an oil free twin screw air expander of 3/5 lobe configuration was estimated by use of full 3D Computational Fluid Dynamics (CFD) applying a procedure similar to that used for screw compressors. The grid generator SCORG© was employed for pre-processing of the moving domains between the rotors while the stationary grids for the ports were derived from a commercial grid generator...

  7. A power recirculating test rig for ball screw endurance tests

    Directory of Open Access Journals (Sweden)

    Giberti Hermes

    2016-01-01

    Full Text Available A conceptual design of an innovative test rig for endurance tests of ball screws is presented in this paper. The test rig layout is based on the power recirculating principle and it also allows to overtake the main critical issues of the ball screw endurance tests. Among these there are the high power required to make the test, the lengthy duration of the same and the high loads between the screw and the frame that holds it. The article describes the test rig designed scheme, the kinematic expedients to be adopted in order to obtain the required performance and functionality and the sizing procedure to choose the actuation system.

  8. Test Research on Special Sucker Rod for Screw Pump

    Institute of Scientific and Technical Information of China (English)

    Zhang Mingyi; Chen Mingzhan; Li Zhi

    2006-01-01

    @@ According to the statistics of straight thread sucker rods' application in screw pump in Daqing Oilfield before2000, the proportion of sucker rods' yearly breakaway reached to 41.6%, taking up 70% of the total wells that were checked. Thus it can be seen that the rods breakaway problem was becoming the main barrier restricting screw pump large-scale population and application. Since then,the development work on the special sucker rods for screw pump had been carried on. Through the analysis on the failure position and failure form of the sucker rods',the following conclusions arepresented:

  9. Migration of polyethylene fixation screw after total knee arthroplasty.

    Science.gov (United States)

    Cho, Woo-Shin; Youm, Yoon-Seok

    2009-08-01

    Duracon (Howmedica, Rutherford, NJ) posterior stabilized total knee system has a snap fit locking mechanism of a tibial polyethylene, including an additional locking screw for further fixation of polyethylene. We report 13 cases of locking screw migration from tibial component after Duracon posterior stabilized primary total knee arthroplasty. Among 13 knees, screw migration in 10 asymptomatic cases was incidentally detected during regular follow-up, and they were just observed in the outpatient clinic. Only 3 knees had moderate pain, swelling, and instability, and revision was done on 2 of 3 knees.

  10. Addressing Stretch Myelopathy in Multilevel Cervical Kyphosis with Posterior Surgery Using Cervical Pedicle Screws

    Science.gov (United States)

    Mahesh, Bijjawara; Vijay, Shekarappa; Arun, Kumar; Srinivasa, Reddy

    2016-01-01

    Study Design Technique description and retrospective data analysis. Purpose To describe the technique of cervical kyphosis correction with partial facetectomies and evaluate the outcome of single-stage posterior decompression and kyphosis correction in multilevel cervical myelopathy. Overview of Literature Kyphosis correction in multilevel cervical myelopathy involves anterior and posterior surgery. With the advent of cervical pedicle screw-rod instrumentation, single-stage posterior kyphosis correction is feasible and can address stretch myelopathy by posterior shortening. Methods Nine patients underwent single-stage posterior decompression and kyphosis correction for multilevel cervical myelopathy using cervical pedicle screw instrumentation from March 2011 to February 2014 and were evaluated preoperatively and postoperatively with modified Japanese Orthopaedic Association (mJOA) scoring and computed tomography scans for radiological measurements. Kyphosis assessment was made with Ishihara curvature index and C2–C7 Cobb's angle. The linear length of the spinal canal and the actual spinal canal length were also evaluated. The average follow-up was 40.56 months (range, 20 to 53 months). Results The average preoperative C2–7 Cobb's angle of 6.3° (1° to 12°) improved to 2° (10° to −9°). Ishihara index improved from −15.8% (−30.5% to −4.7%) to −3.66% (−14.5% to +12.6%). The actual spinal canal length decreased from 83.64 mm (range, 76.8 to 91.82 mm) to 82.68 mm (range, 75.85 to 90.78 mm). The preoperative mJOA score of 7.8 (range, 3 to 11) improved to 15.0 (range, 13 to 17). Conclusions Single-stage posterior decompression and kyphosis correction using cervical pedicle screws for multilevel cervical myelopathy may address stretch myelopathy, in addition to decompression in the transverse plane. However, cervical lordosis was not achieved with this method as predictably as by the anterior approach. The present study shows evidence of mild

  11. Multidisciplinary management of anterior diastemata

    DEFF Research Database (Denmark)

    Furuse, Adilson Yoshio; Herkrath, Fernando José; Franco, Eduardo Jacomino

    2007-01-01

    Anterior diastemata may compromise the harmony of a patient's smile. Consideration of etiologic factors, previous gingival conditioning, and individual treatment planning are essential in the proper management of anterior diastemata. An integrated orthodontic-restorative approach may enhance...... the aesthetic results when orthodontic therapy itself is not feasible. This article presents integrated orthodonticrestorative solutions of anterior diastemata, associated with the conditioning of the gingival tissue with composite resin, and discusses the most relevant aspects related to their etiology...

  12. The finite element analysis and clinical significance of through the mouth atlanto-axial vertebral anterior plate fixation

    Institute of Scientific and Technical Information of China (English)

    LI Xiaohe; LI Zhijun; GAO Shang

    2015-01-01

    Objective:To analysis through the mouth atlanto-axial vertebral anterior plate fixation in finite element for the development of the segmental anterior fixation surgery and to provide the reference of inner plant im-provement. Methods:One case, male, 36 years old, 64 kg weight was randomly selected from January 2014 to our hospital to check no-skull - atlanto-axial vertebral disease . It was scanned by 0. 625 mm thin layer, Image data were rebuilted in the Mimics 16. 01 software, Pro/ENGINEER 4. 0 software was used to rebuilt atlanto-axial vertebral anterior plate, After reconstruction of steel screw 3 d model according to the classic through the mouth , the model was imported into Mimics 16. 01 and the model surface was meshed and material was assigned, The mod-el was forced 80 N vertical loading, the surface was applied 15 nm torque, to simulat three motion state example, forward bends, stretch, side-bending, The stress and deformation of screw and rod were measured. Results: At-lanto-axial vertebral three-dimensional reconstruction model were divided into 14 514 individual grid, 7 257 nodes, the model was loaded, The stress of upper screw root in bend was biggest (62. 34 ±5. 52) Mpa (F=73. 23, P<0. 05, the difference was statistically significant). A screw of the root and the top, lateral stress was the largest, respectively were (78. 42 ± 5. 5. 14) Mpa (F=112. 32, P<0. 05);(95. 48 ± 7. 12 Mpa (F=62. 32, P<0. 05), the difference was statistical significance; Under three different motion state and a screw root stress, Upper screw root stress in bending forward was greater than the lower (forward bends, stretch and lateral bending state , t value were 12. 2, 9. 23, 22. 98, P<0. 05, differences were statistically significant), and in the lateral current screw root stress was greater than the upper; In the same movement state, the top was greater than the root, the differences were statistically significant (forward bends, stretch and lateral bending state after

  13. Centrifuging Step-Screw Conveyor for Regolith Project

    Data.gov (United States)

    National Aeronautics and Space Administration — A variety of ISRU operations will utilize lunar regolith as feedstock. The proposed centrifuging step-screw conveyor concept will provide a well controlled robust,...

  14. Screw-matrix method in dynamics of multibody systems

    Science.gov (United States)

    Yanzhu, Liu

    1988-05-01

    In the present paper the concept of screw in classical mechanics is expressed in matrix form, in order to formulate the dynamical equations of the multibody systems. The mentioned method can retain the advantages of the screw theory and avoid the shortcomings of the dual number notation. Combining the screw-matrix method with the tool of graph theory in Roberson/Wittenberg formalism. We can expand the application of the screw theory to the general case of multibody systems. For a tree system, the dynamical equations for each j-th subsystem, composed of all the outboard bodies connected by j-th joint can be formulated without the constraint reaction forces in the joints. For a nontree system, the dynamical equations of subsystems and the kinematical consistency conditions of the joints can be derived using the loop matrix. The whole process of calculation is unified in matrix form. A three-segment manipulator is discussed as an example.

  15. Kinematic analysis of parallel manipulators by algebraic screw theory

    CERN Document Server

    Gallardo-Alvarado, Jaime

    2016-01-01

    This book reviews the fundamentals of screw theory concerned with velocity analysis of rigid-bodies, confirmed with detailed and explicit proofs. The author additionally investigates acceleration, jerk, and hyper-jerk analyses of rigid-bodies following the trend of the velocity analysis. With the material provided in this book, readers can extend the theory of screws into the kinematics of optional order of rigid-bodies. Illustrative examples and exercises to reinforce learning are provided. Of particular note, the kinematics of emblematic parallel manipulators, such as the Delta robot as well as the original Gough and Stewart platforms are revisited applying, in addition to the theory of screws, new methods devoted to simplify the corresponding forward-displacement analysis, a challenging task for most parallel manipulators. Stands as the only book devoted to the acceleration, jerk and hyper-jerk (snap) analyses of rigid-body by means of screw theory; Provides new strategies to simplify the forward kinematic...

  16. Lumbar pedicle screw placement: Using only AP plane imaging

    Directory of Open Access Journals (Sweden)

    Anil Sethi

    2012-01-01

    Conclusion: Placement of pedicle screws under fluoroscopic guidance using AP plane imaging alone with tactile guidance is safe, fast, and reliable. However, a good understanding of the radiographic landmarks is a prerequisite.

  17. Pullout strength of misplaced pedicle screws in the thoracic and lumbar vertebrae - A cadaveric study

    Directory of Open Access Journals (Sweden)

    Shyam K Saraf

    2013-01-01

    Full Text Available Background: The objective of this cadaveric study was to analyze the effects of iatrogenic pedicle perforations from screw misplacement on the mean pullout strength of lower thoracic and lumbar pedicle screws. We also investigated the effect of bone mineral density (BMD, diameter of pedicle screws, and the region of spine on the pullout strength of pedicle screws. Materials and Methods: Sixty fresh human cadaveric vertebrae (D10-L2 were harvested. Dual-energy X-ray absorptiometry (DEXA scan of vertebrae was done for BMD. Titanium pedicle screws of different diameters (5.2 and 6.2 mm were inserted in the thoracic and lumbar segments after dividing the specimens into three groups: a standard pedicle screw (no cortical perforation; b screw with medial cortical perforation; and c screw with lateral cortical perforation. Finally, pullout load of pedicle screws was recorded using INSTRON Universal Testing Machine. Results: Compared with standard placement, medially misplaced screws had 9.4% greater mean pullout strength and laterally misplaced screws had 47.3% lesser mean pullout strength. The pullout strength of the 6.2 mm pedicle screws was 33% greater than that of the 5.2 mm pedicle screws. The pullout load of pedicle screws in lumbar vertebra was 13.9% greater than that in the thoracic vertebra ( P = 0.105, but it was not statistically significant. There was no significant difference between pullout loads of vertebra with different BMD ( P = 0.901. Conclusion: The mean pullout strength was less with lateral misplaced pedicle screws while medial misplaced pedicle screw had more pullout strength. The pullout load of 6.2 mm screws was greater than that of 5.2 mm pedicle screws. No significant correlation was found between bone mineral densities and the pullout strength of vertebra. Similarly, the pullout load of screw placed in thoracic and lumbar vertebrae was not significantly different.

  18. Pedicle screw fixation against burst fracture of thoracolumbar vertebrae

    Institute of Scientific and Technical Information of China (English)

    L(U) Fu-xin; HUANG Yong; ZHANG Qiang; SHI Feng-lei; ZHAO Dong-sheng; HU Qiao

    2007-01-01

    Objective: To analyze the application of vertebral pedicle screw fixation in the treatment of burst fracture of thoracolumbar vertebrae.Methods: A total of 48 cases (31 males and 17 females, aged from 18-72 years, mean: 41.3 years) with thoracolumbar vertebrae burst fracture were treated by pedicle screw system since January 2004. According to the AO classification of thoracolumbar vertebrae fracture,there are 36 cases of Type A, 9 of Type B and 3 of Type C.Results: All patients were followed up for 6-25 months (average 12 months ), no secondary nerve root injury, spinal cord injury, loosening or breakage of pedicle screw were observed. The nerve function of 29 patients with cauda equina nerve injury was restored to different degrees. The vertebral body height returned to normal level and posterior process angle was rectified after operation.Conclusions: The vertebral pedicle screw internal fixation was technologically applicable, which can efficiently reposition and stablize the bursting fractured vertabrae,indirectly decompress canalis spinalis, maintain spine stablity, scatter stress of screw system, reduce the risk of loosening or breakage of screw and loss of vertebral height,and prevent the formation of posterior convex after operation.

  19. Rapid prototyping drill guide template for lumbar pedicle screw placement

    Institute of Scientific and Technical Information of China (English)

    LU Sheng; XU Yong-qing; ZHANG Yuan-zhi; LI Yan-bing; SHI Ji-hong; CHEN Guo-ping; CHEN Yu-bing

    2009-01-01

    To develop a novel method of spinal pedical stereotaxy by reverse engineering and rapid prototyping techniques, and to validate its accuracy by experimental and clinical studies. Methods: A 3D reconstruction model for the desired lumbar vertebra was generated by using the Mimics 10.11 software, and the optimal screw size and orientation were determined using the reverse engineering software. Afterwards, a drill template was created by reverse engi-neering principle, whose surface was the antitemplate of the vertebral surface. The drill template and its correspond-ing vertebra were manufactured using the rapid prototyping technique. Results: The accuracy of the drill template was con-firmed by drilling screw trajectory into the vertebral biomodel preoperatively. This method also showed its ability to cus-tomize the placement and size of each screw based on the unique morphology of the lumbar vertebra.The drill tem-plate fits the postural surface of the vertebra very well in the cadaver experiment. Postoperative CT scans for controlling the pedicle bore showed that the personalized template had a high precision in cadaver experiment and clinical application. No misplacement occurred by using the per-sonalized template. During surgery, no additional computer assistance was needed.Conclusions: The authors have developed a novel drill template for lumbar pedicle screw placement with good applicability and high accuracy. The potential use of drill templates to place lumbar pedicle screws is promising. Our methodology appears to provide an accurate technique and trajectory for pedicle screw placement in the lumbar spine.

  20. Far cortical locking screws in distal femur fractures.

    Science.gov (United States)

    Adams, John D; Tanner, Stephanie L; Jeray, Kyle J

    2015-03-01

    Distal femur fractures routinely heal by secondary bone healing, which relies on interfragmentary motion. Periarticular locking plates are commonly used for fixation in distal femur fractures but are associated with a high nonunion rate, likely due to the stiffness of the constructs. Far cortical locking (FCL) screws are designed to allow micromotion at the near cortex while maintaining purchase in only the far cortex. Although clinical data are limited, these screws have been shown in biomechanical studies to provide excellent interfragmentary motion, and animal models have shown increased callus formation compared with traditional locking screws. The purpose of this study was to examine the clinical effects that FCL screws have on healing in distal femur fractures treated with locked constructs. In this retrospective case series, 15 patients with a distal femur fracture treated with MotionLoc screws (Zimmer, Warsaw, Indiana) were analyzed. Serial radiographs were evaluated for callus presence and time to union. All fractures were either 33-A3 or 33-C2 according to the AO classification system, and 5 (33%) were open. Bone loss was recorded in 2 patients. There were no nonunions, and average time to union was 24 weeks. There were no implant failures, and all 5 open fractures, including the 2 with bone loss, healed without intervention. There was 1 reoperation due to painful hardware. Although this is a small case series, these results are promising. Far cortical locking screws may provide the answer to the high nonunion rate associated with distal femur fractures treated with traditional locked constructs.

  1. [Anterior cervical hypertrichosis: case report].

    Science.gov (United States)

    Orozco-Gutiérrez, Mario H; Sánchez-Corona, José; García-Ortiz, José E; Castañeda-Cisneros, Gema; Dávalos-Rodríguez, Nory O; Corona-Rivera, Jorge R; García-Cruz, Diana

    2016-10-01

    The non-syndromic anterior cervical hypertrichosis (OMIM N° 600457) is a genetic disorder characterized by a patch of hair at the level of the laryngeal prominence. We present a 12-year-old boy with anterior cervical hypertrichosis and mild generalized hypertrichosis. He has no neurological, ophthalmological or skeletal anomalies. The clinical follow up is 10 years.

  2. Prediction of Deformity Correction by Pedicle Screw Instrumentation in Thoracolumbar Scoliosis Surgery

    Science.gov (United States)

    Kiriyama, Yoshimori; Yamazaki, Nobutoshi; Nagura, Takeo; Matsumoto, Morio; Chiba, Kazuhiro; Toyama, Yoshiaki

    In segmental pedicle screw instrumentation, the relationship between the combinations of pedicle screw placements and the degree of deformity correction was investigated with a three-dimensional rigid body and spring model. The virtual thoracolumbar scoliosis (Cobb’s angle of 47 deg.) was corrected using six different combinations of pedicle-screw placements. As a result, better correction in the axial rotation was obtained with the pedicle screws placed at or close to the apical vertebra than with the screws placed close to the end vertebrae, while the correction in the frontal plane was better with the screws close to the end vertebrae than with those close to the apical vertebra. Additionally, two screws placed in the convex side above and below the apical vertebra provided better correction than two screws placed in the concave side. Effective deformity corrections of scoliosis were obtained with the proper combinations of pedicle screw placements.

  3. Radiological analysis on femoral tunnel positioning between isometric and anatomical reconstructions of the anterior cruciate ligament,

    Directory of Open Access Journals (Sweden)

    Rodrigo Barreiros Vieira

    2014-04-01

    Full Text Available OBJECTIVE: the aim of this study was to radiologically evaluate the femoral tunnel position in anterior cruciate ligament (ACL reconstructions using the isometric and anatomical techniques.METHODS: a prospective analytical study was conducted on patients undergoing ACL reconstruction by means of the isometric and anatomical techniques, using grafts from the knee flexor tendons or patellar tendon. Twenty-eight patients were recruited during the immediate postoperative period, at the knee surgery outpatient clinic of FCMMG-HUSJ. Radiographs of the operated knee were produced in anteroposterior (AP view with the patient standing on both feet and in lateral view with 30◦ of flexion. The lines were traced out and the distances and angles were measured on the lateral radiograph to evaluate the sagittal plane. The distance from the center of the screw to the posterior cortical bone of the lateral condyle was measured and divided by the Blumensaat line. In relation to the height of the screw, the distance from the center of the screw to the joint surface of the lateral condyle of the knee was measured. On the AP radiograph, evaluating the coronal plane, the angle between the anatomical axis of the femur and a line traced at the center of the screw was measured.RESULTS: with regard to the pmeasurement (posteriorization of the interference screw, the tests showed that the p-value (0.4213 was greater than the significance level used (0.05; the null hypothesis was not rejected and it could be stated that there was no statistically significant difference between the anatomical and isometric techniques. With regard to the H measurement (height of the screw in relation to the lower cortical bone of the knee, the p-value observed (0.0006 was less than the significance level used (0.05; the null hypothesis was rejected and it could be stated that there was a statistically significant difference between the anatomical and isometric techniques. It can be

  4. Usefulness of absorbable screws in the Sauvé-Kapandji procedure for rheumatoid wrist reconstruction.

    Science.gov (United States)

    Nakamura, K; Oda, H; Tanaka, S; Kuga, Y; Yamamoto, M; Nishikawa, T; Juji, T; Shimizu, M

    2002-06-01

    Abstract  In the Sauvé-Kapandji (S-K) procedure for rheumatoid wrist reconstruction, the distal end of the ulna is fixed to the radius with screws. Recently, absorbable screws have increasingly been used instead of metal ones. However, the clinical usefulness of absorbable screws in S-K procedures for rheumatoid patients is still unknown. The purpose of this article is to evaluate the effect of absorbable screws in this procedure by comparing their clinical results with those of metal screws. Poly-l-lactic acid (PLLA) absorbable screws were used in 23 wrists, and metal screws were used in 20 wrists. We evaluated the presence of general or local reactions to PLLA, the stability of the ulnar head, the time to bone union, changes in the shape of the distal ulna, and the presence of bone resorption around the screws. There were no complications with the use of PLLA screws, and their fixation stability was adequate to form sufficient bone union. In five cases in the metal screw group, bone resorption around the screws occurred between 1 and 2 years after surgery. Bone resorption around the PLLA screws was not observed. We conclude that absorbable screws may be more useful than metal screws in the S-K procedure for rheumatoid wrist reconstruction.

  5. Development and Testing of X-Ray Imaging-Enhanced Poly-L-Lactide Bone Screws.

    Directory of Open Access Journals (Sweden)

    Wei-Jen Chang

    Full Text Available Nanosized iron oxide particles exhibit osteogenic and radiopaque properties. Thus, iron oxide (Fe3O4 nanoparticles were incorporated into a biodegradable polymer (poly-L-lactic acid, PLLA to fabricate a composite bone screw. This multifunctional, 3D printable bone screw was detectable on X-ray examination. In this study, mechanical tests including three-point bending and ultimate tensile strength were conducted to evaluate the optimal ratio of iron oxide nanoparticles in the PLLA composite. Both injection molding and 3D printing techniques were used to fabricate the PLLA bone screws with and without the iron oxide nanoparticles. The fabricated screws were implanted into the femoral condyles of New Zealand White rabbits. Bone blocks containing the PLLA screws were resected 2 and 4 weeks after surgery. Histologic examination of the surrounding bone and the radiopacity of the iron-oxide-containing PLLA screws were evaluated. Our results indicated that addition of iron oxide nanoparticles at 30% significantly decreased the ultimate tensile stress properties of the PLLA screws. The screws with 20% iron oxide exhibited strong radiopacity compared to the screws fabricated without the iron oxide nanoparticles. Four weeks after surgery, the average bone volume of the iron oxide PLLA composite screws was significantly greater than that of PLLA screws without iron oxide. These findings suggested that biodegradable and X-ray detectable PLLA bone screws can be produced by incorporation of 20% iron oxide nanoparticles. Furthermore, these screws had significantly greater osteogenic capability than the PLLA screws without iron oxide.

  6. Inestabilidad Anterior de Hombro

    Directory of Open Access Journals (Sweden)

    Pablo David Flint Kuran

    2013-11-01

    Full Text Available In­tro­duc­ción La luxación recidivante de hombro es una patología frecuente en pacientes jóvenes, laboralmente activos. Existen numerosas técnicas quirúrgicas para la inestabilidad glenohumeral. La técnica de Bristow, discutida por no ser anatómica y por sus complicaciones, continúa vigente debido al bajo índice de reluxaciones. Los objetivos fueron determinar el índice de recidiva, alteraciones funcionales e índice de consolidación del injerto. Materiales­ y­ Métodos Se evaluaron 24 pacientes del sexo masculino, de entre 19 y 40 años, operados por luxación anterior recidivante de hombro según la técnica de Bristow, entre enero de 2003 y agosto de 2011. Se evaluó la tasa de reluxación, la función articular según el puntaje de Constant y el posicionamiento del injerto con respecto a la superficie articular con tomografía y radiografías para evaluar la consolidación del injerto. Se registraron las complicaciones quirúrgicas. Resultados ­Todos los pacientes eran hombres, con rango de edad de 19 a 40 años. La causa fue traumática en 24 pacientes. Dieciséis pacientes presentaron más de 3 episodios de luxación prequirúrgicos. Según la escala de Constant, 21 obtuvieron entre 96 y 100 puntos, y los restantes, entre 90 y 95 puntos. No hubo nuevos episodios de luxaciones. La tomografía mostró la consolidación en todos los casos. Un paciente tuvo una imagen osteolítica alrededor del tornillo, sin compromiso funcional del hombro. Conclusión La técnica de Bristow para tratar la luxación anterior recidivante de hombro provocó un bajo índice de complicaciones, con resultados funcionales entre excelentes y buenos. No hubo episodios de reluxación y se logró la consolidación del injerto óseo en todos los casos.

  7. The influence of screw configuration on the pretreatment performance of a continuous twin screw-driven reactor (CTSR).

    Science.gov (United States)

    Choi, Chang Ho; Um, Byung-Hwan; Oh, Kyeong Keun

    2013-03-01

    A combination of a continuous twin screw-driven reactor (CTSR) and a dilute acid pretreatment was used for the pretreatment of biomass with a high cellulose content and high monomeric xylose hydrolyzate. With the newly modified CTSR screw configuration (Config. 3), the influences of the screw rotational speed (30-60 rpm), of the pretreatment conditions such as acid concentration (1-5%) and reaction temperature (160-175 °C) at the operating condition of biomass feeding rate (1.0 g/min) and acid feeding rate (13.4 mL/min) on the pretreatment performance were investigated. The cellulose content in the pretreated rape straw was 67.1% at the following optimal conditions: barrel temperature of 165 °C, acid concentration of 3.0% (w/v), and screw rotational speed of 30 rpm. According to the three screw configurations, the glucose yields from enzymatic hydrolysis were 70.1%, 72.9%, and 78.7% for screw Configs. 1, 2, and 3, respectively.

  8. Investigation of an 11mm diameter twin screw granulator: Screw element performance and in-line monitoring via image analysis.

    Science.gov (United States)

    Sayin, Ridade; Martinez-Marcos, Laura; Osorio, Juan G; Cruise, Paul; Jones, Ian; Halbert, Gavin W; Lamprou, Dimitrios A; Litster, James D

    2015-12-30

    As twin screw granulation (TSG) provides one with many screw element options, characterization of each screw element is crucial in optimizing the screw configuration in order to obtain desired granule attributes. In this study, the performance of two different screw elements - distributive feed screws and kneading elements - was studied in an 11 mm TSG at different liquid-to-solid (L/S) ratios. The kneading element configuration was found to break large granules more efficiently, leading to narrower granule size distributions. While pharmaceutical industry shifts toward continuous manufacturing, inline monitoring and process control are gaining importance. Granules from an 11 mm TSG were analysed using the Eyecon™, a real-time high speed direct imaging system, which has been used to capture accurate particle size distribution and particle count. The size parameters and particle count were then assessed in terms of their ability to be a suitable control measure using the Shewhart control charts. d10 and particle count were found to be good indicators of the change in L/S ratio. However, d50 and d90 did not reflect the change, due to their inherent variability even when the process is at steady state.

  9. Reconstruction of anterior cruciate ligament and anterolateral ligament using interlinked hamstrings - technical note.

    Science.gov (United States)

    Ferreira, Marcio de Castro; Zidan, Flavio Ferreira; Miduati, Francini Belluci; Fortuna, Caio Cesar; Mizutani, Bruno Moreira; Abdalla, Rene Jorge

    2016-01-01

    Recent anatomical and biomechanical studies on the anterolateral ligament (ALL) of the knee have shown that this structure has an important function in relation to joint stability, especially when associated with anterior cruciate ligament (ACL) injury. However, the criteria for its reconstruction have not yet been fully established and the surgical techniques that have been described present variations regarding anatomical points and fixation materials. This study presents a reproducible technique for ALL and ACL reconstruction using hamstring tendons, in which three interference screws are used for fixation.

  10. Helical Screw Expander Evaluation Project. Final report

    Energy Technology Data Exchange (ETDEWEB)

    McKay, R.

    1982-03-01

    A functional 1-MW geothermal electric power plant that featured a helical screw expander was produced and then tested in Utah in 1978 to 1979 with a demonstrated average performance of approximately 45% machine efficiency over a wide range of test conditions in noncondensing operation on two-phase geothermal fluids. The Project also produced a computer-equipped data system, an instrumentation and control van, and a 1000-kW variable load bank, all integrated into a test array designed for operation at a variety of remote test sites. Additional testing was performed in Mexico in 1980 under a cooperative test program using the same test array, and machine efficiency was measured at 62% maximum with the rotors partially coated with scale, compared with approximately 54% maximum in Utah with uncoated rotors, confirming the importance of scale deposits within the machine on performance. Data are presented for the Utah testing and for the noncondensing phases of the testing in Mexico. Test time logged was 437 hours during the Utah tests and 1101 hours during the Mexico tests.

  11. PEACH POMACE PROCESSING USING TWIN SCREW EXTRUSION

    Directory of Open Access Journals (Sweden)

    Preetam Sarkar

    2014-02-01

    Full Text Available Fruit by-products have found limited applications in the food industry. They have been primarily used as animal feed, applied to agricultural land for soil amendment or composted and applied to farms for growing crops. Some of these disposal methods are not environment friendly, while others are costly. This study was undertaken to examine the possibility of utilizing peach pomace as a source of soluble dietary fiber in expanded extruded food products. Peach pomace was combined with rice flour at four different levels. The four blends were mixed, dried to a moisture level of 13.5% (w/w and ground to flour. These blends were extruded in a twin-screw extruder (Clextral EV-25 at a feed flow rate of 15 kg/h. The extruded products were analyzed for physical and textural properties. The apparent and true densities for the extrudates decreased from 183.93 to 133.94 kg/m3 and 1275.31 to 1171.2 kg/m3, respectively. A linear increase in extrudate porosity (85.11-88.54% and radial expansion ratio (13.5-19.3 and a steady decrease in breaking strength (104-50.74 kPa were observed with increasing peach pomace level in the blends. This study demonstrates the potential of extrusion processing as a tool for fruit by-product utilization, which will not only enhance consumption of soluble dietary fiber but will also increase the overall fruit utilization.

  12. Patella fracture following anterior cruciate ligament reconstruction: A case report

    Directory of Open Access Journals (Sweden)

    Milankov Miroslav

    2003-01-01

    Full Text Available Introduction The most frequent procedure in treatment of acute or chronic anterior cruciate ligament (ACL rupture is the so called bone-tendon-bone reconstruction. A transverse dislocated patella fracture is a rare complication of this procedure with an incidence of 0.23%-2.3%. In a five year period, (1998-2002, 407 arthroscopic reconstructions of the anterior cruciate ligaments were done at our Clinic, and there was only one case of patella fracture. Case report An 18-year-old female patient, a handball player, suffered an acute rupture of anterior cruciate ligament of the left knee, so arthroscopic bone-tendon-bone reconstruction of the anterior cruciate ligament was performed. After adequate skin incision, a bone graft was taken from the patella and upper part of trapezoid tibia, which was 25 mm long, 10 mm wide and 5 mm thick, together with a part of patellar ligament. After the remains of the anterior cruciate ligament had been arthroscopically removed, tunnels were made in tibia and femur and a graft was inserted and fixed with two metal interference screws. Knee stability was tested, and drainage was put in the knee joint. The wound was closed by layers. The quadriceps exercises and passive knee movements started immediately. Full range of movements was accomplished six weeks later when the patient started to walk with full weight-bearing on her operated leg. Three weeks later, (nine weeks after the operation, the patient has accidentally lost her balance and fell. A transverse, dislocated fracture of the left patella was diagnosed and osteosynthesis of the fractured patella with two Kirschner wires and a metallic loop was performed. Postoperatively, full range of movement was allowed. Six months later, the patient felt no pain, there was no swelling, full range of knee movement was achieved, while the Lachman Test was identical in both knees and the pivot shift test was negative. Discussion Fracture of patella after ACL reconstruction is

  13. Sacroiliac secure corridor: analysis for safe insertion of iliosacral screws

    Directory of Open Access Journals (Sweden)

    Henrique Alves Cruz

    2013-08-01

    Full Text Available OBJECTIVE: Posterior pelvic lesions, especially of the sacral-iliac joint, have high mortality and morbidity risks. Definitive fixation is necessary for the joint stabilization, and one option is the sacral percutaneous pinning with screws. Proximity to important structures to this region brings risks to the fixation procedure; therefore, it is important to know the tridimensional anatomy of the pelvis posterior region. Deviations of the surgeon's hand of four degrees may target the screws to those structures; dimorphisms of the upper sacrum and a poor lesion reduction may redound in a screw malpositioning. This study is aimed to evaluate the dimensions of a safe surgical corridor for safe sacroiliac screw insertion and relations with age and sex of the patients. METHOD: One hundred randomly selected pelvis CTs of patients with no pelvic diseases, seen at a tertiary care teaching Hospital. Measurements were made by computer and the safest area for screw insertion was calculated by two methods. The results were expressed in mm (not in degrees, in order to be a further surgical reference. RESULTS: There was a significant size difference in the analyzed sacral vertebra, differing on a wider size in men than in women. There was no significant statistical difference between vertebral size and age. By both methods, a safe area for screw insertion could be defined. CONCLUSION: Age does not influence the width of the surgical corridor. The surgeon has a safe corridor considered narrower when inserting screws in a female pelvis than when in a male one. However, as the smallest vertebra found (feminine was considered for statics, it was concluded that this corridor is 20 mm wide in any direction, taking as a reference the centrum of the vertebra.

  14. Application of Patient-Specific Drill Template in the Thoracic and Cervical Pedicle Screw Implanta-tion:a Clinical Study%3D 打印个体化导航模板在胸椎和颈椎椎弓根螺钉植入的临床应用

    Institute of Scientific and Technical Information of China (English)

    宁金沛; 吴卫东; 覃求; 梁柱德; 韦武; 何恩谋; 潘式新

    2015-01-01

    Objective To investigate the accuracy and safety of patient-specific drill template in the thoracic and cervical pedi-cle screw implantation. Methods From July 2014 to November 2014,7 patients needed cervical and thoracic pedicle screw placements underwent CT scan,then Mimics 15. 0 was used to reconstruct 3D model of cervical and thoracic spine. The best drilling tracts and 3D model of patient-specific drill template were designed by Geomagic software. The 3D models above were used to print out with a rapid prototyping(RP)machine and the real drill templates were used to guide screws placement. 24 transpedicular screws were implanted into cervical and thoracic pedicle. The complications related to screws placement were re-corded. Results 23 of the 24 screws implanted by drill plate guidance were completed located in the pedicle. Just 1 screw vio-lation was observed,but the violation distance was less than 1. 2 mm. The placement accurate rate was 96% . The accuracy ac-ceptance rate was 100% . No neurovascular and visceral injury related-complications was noted. Conclusion Patient-specific biocompatible drill template is reliable and safe in the thoracic and cervical pedicle screw implantation.%目的:研究数字化(3D)打印技术的个性化导航模板设计在胸椎和颈椎手术个性化置钉应用的准确性和安全性。方法2014年7月至2014年11月,对7例需要行胸椎、颈椎椎弓根螺钉植入手术的患者术前通过 CT 扫描、Mimics 软件三维重建建立三维仿真模型。并使用 Geomagic 软件设计最佳的内固定钉道,然后根据钉道设计导航模板,用3D 打印机打印导航模板,用于手术时辅助置钉;术中辅助植入胸椎、颈椎椎弓根螺钉共24枚,术后 CT 扫描评价螺钉位置,记录有无与螺钉植入的相关并发症。结果通过导航模板辅助植入的24枚椎弓根螺钉,23枚完全在椎弓根内,1枚穿破椎弓根外壁,穿出距离均小于1.2 mm

  15. A biomechanical study of two different pedicle screw methods for fixation in osteoporotic and nonosteoporotic vertebrae.

    Science.gov (United States)

    Higashino, Kosaku; Kim, Jin Hwan; Horton, William C; Hutton, William C

    2012-01-01

    In reconstruction of the osteoporotic spine, patients often show poor outcome because of pedicle screw failure. This study used osteoporotic and nonosteoporotic vertebrae to determine the difference in fixation strength between pedicle screws inserted straight forward and pedicle screws inserted in an upward trajectory toward the superior end plate (i.e., end-plate screws). There is some evidence to suggest that end-plate screws have a strength advantage. The particular focus was on osteoporotic vertebrae. Thirty-three vertebrae (T10-L2) were harvested. The bone mineral density (BMD) was measured: 15 vertebrae were greater than 0.8 g/cm(2) and designated as nonosteoporotic (average BMD 1.146 ± 0.186 g/cm(2)) and 18 vertebrae were designated as osteoporotic (average BMD 0.643 ± 0.088 g/cm(2)). On one pedicle the screw was inserted straight forward and on the other pedicle the screw was inserted as an end-plate screw. The torque of insertion was measured (Proto 6106 torque screwdriver). Using an MTS Mini Bionix, two types of mechanical testing were carried out on each pedicle: (a) cephalocaudad toggling was first carried out to simulate some physiological type loading: 500 cycles at 0.3 Hz, at ±50 N; and (b) then each pedicle screw was pulled out at a displacement rate of 12.5 cm/min.There was no difference in pullout force between the pedicle screws inserted straight forward and the pedicle screws inserted as end-plate screws. This result applies whether the vertebrae were osteoporotic or nonosteoporotic. For both the straight-forward screws and the end-plate screws, a statistically significant correlation was observed between torque of insertion and pullout force. The results of this experiment indicate that pedicle screws inserted as end-plate screws do not provide a strength advantage over pedicle screws inserted straight forward, whether the vertebrae are osteoporotic or not.

  16. Interfragmentary compression forces of scaphoid screws in a sawbone cylinder model.

    Science.gov (United States)

    Hausmann, J T; Mayr, W; Unger, E; Benesch, T; Vécsei, V; Gäbler, C

    2007-07-01

    Various screws have been developed to stabilise fractures of the scaphoid. Commonly used are the Herbert, the HBS, the 3-mm AO and the Acutrak screws. Not long ago a new screw, the Twin Fix, was introduced. This is cannulated and similar in shape and appearance to the classical Herbert screw. In our test series we compared the maximum achievable compression forces of the Twin Fix screw with that of three other screws (AO, HBS and Acutrak screws). To avoid the variations of density, stiffness and rigidity in natural bone, a polyurethane sawbone-based test setup was used. The test series included 10 screws of each type. The compression force was measured using a special strain gauge. The mean compression force was significantly higher for the Twin Fix screw (8+/-1N) and the Acutrak screw (7.6+/-0.4/0.6N) in relation to the AO screw (6.8+/-1.0/1.4N) and HBS screw (2+/-1N). We found the Twin Fix and Acutrak screws to be promising in the treatment of scaphoid fractures.

  17. Studies on positive conveying in helically channeled single screw extruders

    Directory of Open Access Journals (Sweden)

    L. Pan

    2012-07-01

    Full Text Available A solids conveying theory called double-flight driving theory was proposed for helically channeled single screw extruders. In the extruder, screw channel rotates against static barrel channel, which behaves as cooperative embedded twin-screws for the positive conveying. They turn as two parallel arc plates, between which an arc-plate solid-plug was assumed. By analyzing the forces on the solid-plug in the barrel channel and screw channel, the boundary conditions when the solid-plug is waived of being cut off on barrel wall, were found to have the capacity of the positive conveying. Experimental data were obtained using a specially designed extruder with a helically channeled barrel in the feeding zone and a pressure-adjustable die. The effects of the barrel channel geometry and friction coefficients on the conveying mechanism were presented and compared with the experimental results. The simulations showed that the positive conveying could be achieved after optimizing extruder designs. Compared with the traditional design with the friction-drag conveying, the throughput is higher while screw torque and energy consumption are decreased. Besides, the design criteria of the barrel channel were also discussed.

  18. Numerical simulation of a twin screw expander for performance prediction

    Science.gov (United States)

    Papes, Iva; Degroote, Joris; Vierendeels, Jan

    2015-08-01

    With the increasing use of twin screw expanders in waste heat recovery applications, the performance prediction of these machines plays an important role. This paper presents a mathematical model for calculating the performance of a twin screw expander. From the mass and energy conservation laws, differential equations are derived which are then solved together with the appropriate Equation of State in the instantaneous control volumes. Different flow processes that occur inside the screw expander such as filling (accompanied by a substantial pressure loss) and leakage flows through the clearances are accounted for in the model. The mathematical model employs all geometrical parameters such as chamber volume, suction and leakage areas. With R245fa as working fluid, the Aungier Redlich-Kwong Equation of State has been used in order to include real gas effects. To calculate the mass flow rates through the leakage paths formed inside the screw expander, flow coefficients are considered as constant and they are derived from 3D Computational Fluid Dynamic calculations at given working conditions and applied to all other working conditions. The outcome of the mathematical model is the P-V indicator diagram which is compared to CFD results of the same twin screw expander. Since CFD calculations require significant computational time, developed mathematical model can be used for the faster performance prediction.

  19. Numerical and experimental study of an Archimedean Screw Generator

    Science.gov (United States)

    Dellinger, G.; Garambois, P.-A.; Dufresne, M.; Terfous, A.; Vazquez, J.; Ghenaim, A.

    2016-11-01

    Finding new, safe and renewable energy is becoming more and more of a priority with global warming. One solution that is gaining popularity is the Archimedean Screw Generator (ASG). This kind of hydroelectric plant allows transforming potential energy of a fluid into mechanical energy and is convenient for low-head hydraulic sites. As it is a new and growing technology, there are few references dealing with their design and performance optimization. The present contribution proposes to investigate experimentally and numerically the ASG performances. The experimental study is performed for various flow conditions and a laboratory scale screw device installed at the fluid mechanics laboratory of the INSA of Strasbourg. The first results show that the screw efficiencies are higher than 80% for various hydraulic conditions. In order to study the structure of 3D turbulent flows and energy losses in a screw, the 3D Navier Stokes equations are solved with the k-w SST turbulence model. The exact geometry of the laboratory-scale screw was used in these simulations. Interestingly, the modeled values of efficiency are in fairly good agreement with experimental results while any friction coefficient is involved.

  20. Percutaneous Iliac Screws for Minimally Invasive Spinal Deformity Surgery

    Directory of Open Access Journals (Sweden)

    Michael Y. Wang

    2012-01-01

    Full Text Available Introduction. Adult spinal deformity (ASD surgeries carry significant morbidity, and this has led many surgeons to apply minimally invasive surgery (MIS techniques to reduce the blood loss, infections, and other peri-operative complications. A spectrum of techniques for MIS correction of ASD has thus evolved, most recently the application of percutaneous iliac screws. Methods. Over an 18 months 10 patients with thoracolumbar scoliosis underwent MIS surgery. The mean age was 73 years (70% females. Patients were treated with multi-level facet osteotomies and interbody fusion using expandable cages followed by percutaneous screw fixation. Percutaneous iliac screws were placed bilaterally using the obturator outlet view to target the ischial body. Results. All patients were successfully instrumented without conversion to an open technique. Mean operative time was 302 minutes and the mean blood loss was 480 cc, with no intraoperative complications. A total of 20 screws were placed successfully as judged by CT scanning to confirm no bony violations. Complications included: two asymptomatic medial breaches at T10 and L5, and one patient requiring delayed epidural hematoma evacuation. Conclusions. Percutaneous iliac screws can be placed safely in patients with ASD. This MIS technique allows for successful caudal anchoring to stress-shield the sacrum and L5-S1 fusion site in long-segment constructs.

  1. Treatment of scaphoid waist fractures with the HCS screw

    Directory of Open Access Journals (Sweden)

    Gehrmann, Sebastian V.

    2014-11-01

    Full Text Available The aim of the study was to evaluate the clinical results of the Headless Compression Screw (HCS, Synthes when used for treatment of acute scaphoid waist fractures. The new screw design generates interfragmentary compression with use of a compression sleeve. Twenty-one patients were treated for acute scaphoid waist fractures type B2 with HCS screws. The average time to the final follow-up examination was 12.8 months. All 21 fractures united after a mean time of 7.2 weeks. The mean DASH score was 7.1. The average motion of the wrist in extension was 61°, flexion was 46°, radial abduction reached 25° and the ulnar abduction was 31°. The maximally achieved grip strength was 86% compared to the uninjured side. Treatment of type B2 scaphoid fractures with the Headless Compression Screw showed good functional and radiographic results. The results are similar to those identified using other screw fixation systems.

  2. Screw dislocations in GaN grown by different methods

    Energy Technology Data Exchange (ETDEWEB)

    Liliental-Weber, Z.; Zakharov, D.; Jasinski, J.; O' Keefe, M.A.; Morkoc, H.

    2003-05-27

    A study of screw dislocations in Hydride-Vapor-Phase-Epitaxy (HVPE) template and Molecular-Beam-Epitaxy (MBE) over-layers was performed using Transmission Electron Microscopy (TEM) in plan-view and in cross-section. It was observed that screw dislocations in the HVPE layers were decorated by small voids arranged along the screw axis. However, no voids were observed along screw dislocations in MBE overlayers. This was true both for MBE samples grown under Ga-lean and Ga-rich conditions. Dislocation core structures have been studied in these samples in the plan-view configuration. These experiments were supported by image simulation using the most recent models. A direct reconstruction of the phase and amplitude of the scattered electron wave from a focal series of high-resolution images was applied. It was shown that the core structures of screw dislocations in the studied materials were filled. The filed dislocation cores in an MBE samples were stoichiometric. However, in HVPE materials, single atomic columns show substantial differences in intensities and might indicate the possibility of higher Ga concentration in the core than in the matrix. A much lower intensity of the atomic column at the tip of the void was observed. This might suggest presence of lighter elements, such as oxygen, responsible for their formation.

  3. Screw theoretic view on dynamics of spatially compliant beam

    Institute of Scientific and Technical Information of China (English)

    Xi-lun DING; J.M.SELIG

    2010-01-01

    Beams with spatial compliance can be deformed as bending in a plane,twisting,and extending.In terms of the screw theory on rigid body motions,the concept of"deflection screw"is introduced,a spatial compliant beam theory via the deflection screw is proposed,and the spatial compliance of such a beam system is presented and analysed based on the material theory and fundamental kinematic assumptions.To study the dynamics of the spatially compliant beam,the potential energy and the kinetic energy of the beam are discussed by using the screw theory to obtain the Lagrangian.The Rayleigh-Ritz method is used to compute the vibrational frequencies based on discussions of boundary conditions and shape functions.The eigenfrequencies of the beam with spatial compliance are compared with those of individual deformation cases,pure bending,extension,or torsion.Finally,dynamics of a robot with two spatial compliant links and perpendicular joints is studied using the spatial compliant beam theory.Coupling between the joint rigid body motions and the deformations of spatial compliant links can easily be found in dynamic simulation.The study shows the effectiveness of using the screw theory to deal with the problems of dynamic modeling and analysis of mechanisms with spatially compliant links.

  4. Anterior chamber depth during hemodialysis

    Directory of Open Access Journals (Sweden)

    Gracitelli CPB

    2013-08-01

    Full Text Available Carolina Pelegrini Barbosa Gracitelli,1 Francisco Rosa Stefanini,1 Fernando Penha,1 Miguel Ângelo Góes,2 Sérgio Antonio Draibe,2 Maria Eugênia Canziani,2 Augusto Paranhos Junior1 1Ophthalmology Department, 2Division of Nephrology, Federal University of São Paulo – UNIFESP, São Paulo, Brazil Background: Exacerbation of chronic glaucoma or acute glaucoma is occasionally observed in patients undergoing hemodialysis (HD because of anterior chamber depth changes during this therapy. Purpose: To evaluate anterior chamber depth and axial length in patients during HD sessions. Methods: A total of 67 eyes of 35 patients were prospectively enrolled. Axial length and anterior chamber depth were measured using ultrasonic biometry, and these measures were evaluated at three different times during HD sessions. Body weight and blood pressure pre- and post-HD were also measured. Results: There was no difference in the axial length between the three measurements (P = 0.241. We observed a significantly decreased anterior chamber depth (P = 0.002 during HD sessions. Conclusion: Our results support the idea that there is a change in anterior chamber depth in HD sessions. Keywords: anterior chamber, hemodialysis, axial length, acute angle-closure glaucoma

  5. Diffuse anterior retinoblastoma: current concepts

    Directory of Open Access Journals (Sweden)

    Yang J

    2015-07-01

    Full Text Available Jing Yang,1–3 Yalong Dang,1–3 Yu Zhu,1 Chun Zhang2,3 1Department of Ophthalmology, The First Affiliated Hospital, Zhengzhou University, Zhengzhou City, Henan Province, 2Department of Ophthalmology, Peking University Third Hospital, 3Clinical Stem Cell Research Center, Peking University Third Hospital, Beijing, People’s Republic of China Abstract: Diffuse anterior retinoblastoma is a rare variant of retinoblastoma seeding in the area of the vitreous base and anterior chamber. Patients with diffuse anterior retinoblastoma are older than those with the classical types, with the mean age being 6.1 years. The original cells of diffuse anterior retinoblastoma are supposed to be cone precursor. Patients most commonly present with pseudouveitis, pseudohypopyon, and increased intraocular pressure. The retina under fundus examination is likely to be normal, and the clinical features mimic the inflammation progress, which can often lead to misdiagnosis. The published diffuse anterior retinoblastoma cases were diagnosed after fine-needle aspiration biopsy running the potential risk of inducing metastasis. The most common treatment for diffuse anterior retinoblastoma is enucleation followed by systematic chemotherapy according to the patient’s presentation and clinical course. This review summarizes the recent advances in etiology (including tumorigenesis and cell origin, pathology, diagnosis, differential diagnosis, and new treatment. The challenges of early diagnosis and prospects are also discussed. Keywords: pathology, microenvironment, treatment, diagnosis 

  6. Screw Performance Degradation Assessment Based on Quantum Genetic Algorithm and Dynamic Fuzzy Neural Network

    Directory of Open Access Journals (Sweden)

    Xiaochen Zhang

    2015-01-01

    Full Text Available To evaluate the performance of ball screw, screw performance degradation assessment technology based on quantum genetic algorithm (QGA and dynamic fuzzy neural network (DFNN is studied. The ball screw of the CINCINNATIV5-3000 machining center is treated as the study object. Two Kistler 8704B100M1 accelerometers and a Kistler 8765A250M5 three-way accelerometer are installed to monitor the degradation trend of screw performance. First, screw vibration signal features are extracted both in time domain and frequency domain. Then the feature vectors can be obtained by principal component analysis (PCA. Second, the initialization parameters of the DFNN are optimized by means of QGA. Finally, the feature vectors are inputted to DFNN for training and then get the screw performance degradation model. The experiment results show that the screw performance degradation model could effectively evaluate the performance of NC machine screw.

  7. Instantaneous screws of weight-bearing knee: what can the screws tell us about the knee motion.

    Science.gov (United States)

    Wolf, Alon

    2014-07-01

    There are several ways to represent a given object's motion in a 3D space having 6DOF i.e., three translations and three rotations. Some of the methods that are used are mathematical and do not provide any geometrical insight into the nature of the motion. Screw theory is a mathematical, while at the same time, geometrical method in which the 6DOF motion of an object can be represented. We describe the 6DOF motion of a weight-bearing knee by its screw parameters, that are extracted from 3D Optical Reflective motion capture data. The screw parameters which describe the transformation of the shank with respect to the thigh in each two successive frames, is represented as the instantaneous screw axis of the motion given in its Plücker line coordinate, along with its corresponding pitch and intensity values. Moreover, the Striction curve associated with the motion provides geometrical insight into the nature of the motion and its repeatability. We describe the theoretical background and demonstrate what the screw can tell us about the motion of healthy subjects' knee.

  8. [Midcarpal fusion using break-away compression screw].

    Science.gov (United States)

    Maire, N; Facca, S; Gouzou, S; Liverneaux, P

    2012-02-01

    Indication of midcarpal fusion is SNAC or SLAC wrist grade 3. The main complication of circular plate (most common technique) is non-union. In this context, the purpose of our work was to propose the use of break-away compression screws to decrease the rate of non-union. Our series included ten patients. The fusion was fixed using two break-away compression screws (2mm diameter). No bone graft was used. As assessment, subjective (pain, Quick-DASH) and objective (strength, mobility) criteria were reviewed at follow-up. All the criteria were significantly improved after operation except mobility. Among the complications, we noticed one delayed bone-healing with a good outcome and a radiological consolidation. Midcarpal fusion by dorsal approach using break-away compression screws appears to us a technique of interest, not requiring a bone graft, with good cost effectiveness.

  9. Error Analysis of Robotic Assembly System Based on Screw Theory

    Institute of Scientific and Technical Information of China (English)

    韩卫军; 费燕琼; 赵锡芳

    2003-01-01

    Assembly errors have great influence on assembly quality in robotic assembly systems. Error analysis is directed to the propagations and accumula-tions of various errors and their effect on assembly success.Using the screw coordinates, assembly errors are represented as "error twist", the extremely compact expression. According to the law of screw composition, relative position and orientation errors of mating parts are computed and the necessary condition of assembly success is concluded. A new simple method for measuring assembly errors is also proposed based on the transformation law of a screw.Because of the compact representation of error, the model presented for error analysis can be applied to various part- mating types and especially useful for error analysis of complexity assembly.

  10. Optically driven Archimedes micro-screws for micropump application.

    Science.gov (United States)

    Lin, Chih-Lang; Vitrant, Guy; Bouriau, Michel; Casalegno, Roger; Baldeck, Patrice L

    2011-04-25

    Archimedes micro-screws have been fabricated by three-dimensional two-photon polymerization using a Nd:YAG Q-switched microchip laser at 532nm. Due to their small sizes they can be easily manipulated, and made to rotate using low power optical tweezers. Rotation rates up to 40 Hz are obtained with a laser power of 200 mW, i.e. 0.2 Hz/mW. A photo-driven micropump action in a microfluidic channel is demonstrated with a non-optimized flow rate of 6 pL/min. The optofluidic properties of such type of Archimedes micro-screws are quantitatively described by the conservation of momentum that occurs when the laser photons are reflected on the helical micro-screw surface.

  11. Augmentation of Pedicle Screw Fixation with Calcium Phosphate Cement

    Institute of Scientific and Technical Information of China (English)

    YANG Shu-hua; FU De-hao; LI Jin; XU Wei-hua; YANG Cao; YE Zhe-wei; ZUO Xiao-yan

    2004-01-01

    To determine whether a biodegradable calcium phosphate cement(CPC) provides significant augmentation of pedicle screw fixation or not,an in vitro biomechanical study was carried out to evaluate the biomechanical effect of CPC in the restoration and augmentation of pedicle screw fixation.Axial pullout test and cyclic bending resistance test were employed in the experiment,and polymethylmethacrylate (PMMA) was chosen as control.The results demonstrate that the pullout strengths following CPC restoration and augmentation are 74% greater on an average than those of the control group,but less than those of PMMA restoration group and augmentation group respectively (increased by 126% versus control).In cyclic bending resistance test,the CPC augmented screws are found to withstand a greater number of cycles or greater loading with less displacement before loosening,but the augmentation effect of PMMA is greater than that of CPC.

  12. Free-hand thoracic pedicle screws placed by neurosurgery residents: a CT analysis

    OpenAIRE

    Wang, Vincent Y.; Chin, Cynthia T.; Lu, Daniel C.; Smith, Justin S.; Chou, Dean

    2010-01-01

    Free-hand thoracic pedicle screw placement is becoming more prevalent within neurosurgery residency training programs. This technique implements anatomic landmarks and tactile palpation without fluoroscopy or navigation to place thoracic pedicle screws. Because this technique is performed by surgeons in training, we wished to analyze the rate at which these screws were properly placed by residents by retrospectively reviewing the accuracy of resident-placed free-hand thoracic pedicle screws u...

  13. Posterior atlantoaxial transpedicle screw fixation for traumatic atlatoaxial instability

    Directory of Open Access Journals (Sweden)

    Zheng-lei WANG

    2015-10-01

    Full Text Available Objective To explore the clinical efficacy of posterior atlantoaxial pedicle screw fixation for traumatic atlantoaxial instability. Methods From September 2009 to March 2013, 17 patients with atlantoaxial instability received posterior atlantoaxial pedicle screw fixation. There were 12 males and 5 females, with a mean age of 42 years old (ranged from 19 to 63 years old. Transpedicle screw fixation was employed in 8 patients with atlantoaxial fracture and dislocation, in 2 with traumatic disruption of transverse atlantal ligament, and in 7 with odontoid fracture. The Japanese Orthopaedic Association (JOA score before operation was from 5 to 14, with a mean of 11.2. Preoperative CT, MRI and radiographs, as well as intraoperative screw placement and bone graft were administered in all the patients. Results In all the patients, complete reduction was achieved without injury to the vertebral artery, spinal cord or never root, and they started to be ambulatory on the first day after the operation. The patients were followed up for 6-36 months (mean 21 months, and clinical symptoms were seen to be improved significantly. Imaging reexamination 6 months after the surgery showed satisfactory healing of implanted bone and position of all the screws without loosening of the implant. The mean JOA scores was 15.5(11.0-17.0 twelve months after the operation. Conclusion Atlantoaxial pedicle screw fixation for traumatic atlantoaxial instability is safe and reliable with a favorable clinical result. DOI: 10.11855/j.issn.0577-7402.2015.09.14

  14. Screw-in forces during instrumentation by various file systems

    Science.gov (United States)

    2016-01-01

    Objectives The purpose of this study was to compare the maximum screw-in forces generated during the movement of various Nickel-Titanium (NiTi) file systems. Materials and Methods Forty simulated canals in resin blocks were randomly divided into 4 groups for the following instruments: Mtwo size 25/0.07 (MTW, VDW GmbH), Reciproc R25 (RPR, VDW GmbH), ProTaper Universal F2 (PTU, Dentsply Maillefer), and ProTaper Next X2 (PTN, Dentsply Maillefer, n = 10). All the artificial canals were prepared to obtain a standardized lumen by using ProTaper Universal F1. Screw-in forces were measured using a custom-made experimental device (AEndoS-k, DMJ system) during instrumentation with each NiTi file system using the designated movement. The rotation speed was set at 350 rpm with an automatic 4 mm pecking motion at a speed of 1 mm/sec. The pecking depth was increased by 1 mm for each pecking motion until the file reach the working length. Forces were recorded during file movement, and the maximum force was extracted from the data. Maximum screw-in forces were analyzed by one-way ANOVA and Tukey's post hoc comparison at a significance level of 95%. Results Reciproc and ProTaper Universal files generated the highest maximum screw-in forces among all the instruments while M-two and ProTaper Next showed the lowest (p < 0.05). Conclusions Geometrical differences rather than shaping motion and alloys may affect the screw-in force during canal instrumentation. To reduce screw-in forces, the use of NiTi files with smaller cross-sectional area for higher flexibility is recommended. PMID:27847752

  15. Virtual estimates of fastening strength for pedicle screw implantation procedures

    Science.gov (United States)

    Linte, Cristian A.; Camp, Jon J.; Augustine, Kurt E.; Huddleston, Paul M.; Robb, Richard A.; Holmes, David R.

    2014-03-01

    Traditional 2D images provide limited use for accurate planning of spine interventions, mainly due to the complex 3D anatomy of the spine and close proximity of nerve bundles and vascular structures that must be avoided during the procedure. Our previously developed clinician-friendly platform for spine surgery planning takes advantage of 3D pre-operative images, to enable oblique reformatting and 3D rendering of individual or multiple vertebrae, interactive templating, and placement of virtual pedicle implants. Here we extend the capabilities of the planning platform and demonstrate how the virtual templating approach not only assists with the selection of the optimal implant size and trajectory, but can also be augmented to provide surrogate estimates of the fastening strength of the implanted pedicle screws based on implant dimension and bone mineral density of the displaced bone substrate. According to the failure theories, each screw withstands a maximum holding power that is directly proportional to the screw diameter (D), the length of the in-bone segm,ent of the screw (L), and the density (i.e., bone mineral density) of the pedicle body. In this application, voxel intensity is used as a surrogate measure of the bone mineral density (BMD) of the pedicle body segment displaced by the screw. We conducted an initial assessment of the developed platform using retrospective pre- and post-operative clinical 3D CT data from four patients who underwent spine surgery, consisting of a total of 26 pedicle screws implanted in the lumbar spine. The Fastening Strength of the planned implants was directly assessed by estimating the intensity - area product across the pedicle volume displaced by the virtually implanted screw. For post-operative assessment, each vertebra was registered to its homologous counterpart in the pre-operative image using an intensity-based rigid registration followed by manual adjustment. Following registration, the Fastening Strength was computed

  16. The best location for proximal locking screw for femur interlocking nailing: A biomechanical study

    Directory of Open Access Journals (Sweden)

    Ahmet A Karaarslan

    2016-01-01

    Conclusion: According to our findings, there is twice as much difference in locking screw bending resistance between these two application levels. To avoid proximal locking screw deformation, locking screws should be placed in the level of the lesser trochanter in nailing of 1/3 middle and distal femur fractures.

  17. 46 CFR 154.524 - Piping joints: Welded and screwed couplings.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 5 2010-10-01 2010-10-01 false Piping joints: Welded and screwed couplings. 154.524... Equipment Cargo and Process Piping Systems § 154.524 Piping joints: Welded and screwed couplings. Pipe... warmer. (d) Screwed couplings are allowed for instrumentation and control piping that meets §...

  18. A universal pedicle screw and V-rod system for lumbar isthmic spondylolysis: a retrospective analysis of 21 cases.

    Directory of Open Access Journals (Sweden)

    Xiong-sheng Chen

    Full Text Available OBJECTIVE: To investigate the surgical outcome of a universal pedicle screw-V rod system and isthmic bone grafting for isthmic spondylolysis. METHODS: Twenty-four patients with isthmic spondylolysis at L5 and grade 0-I spondylolisthesis (Meyerding classification received isthmic bone graft and stabilization using the universal pedicle screw-V rod system. Back pain was evaluated using the visual analog scale (VAS and time to bone healing, improvement in spondylolisthesis and intervertebral space height at L5/S1 and L4/L5 were assessed. RESULTS: Twenty-one patients were followed up for 24 months and included in the analysis. Back pain was markedly improved at 3 months postoperatively with a statistical difference in VAS scores compared with preoperative VAS scores (P<0.001. The VAS scores were 0 to 3 at 6 months postoperatively in all patients and no back pain was reported in all patients except 2 patients who complained of back pain after prolonged sitting. X-ray examination showed a bone graft healing time of 3 to 12 months. Grade I spondylolisthesis improved to grade 0 in 4 patients and no noticeable change was observed in the remaining 17 cases. The intervertebral space height at L5/S1 was statistically increased (P<0.05 while no statistically significant change was seen at L4/L5. There was no statistically significant difference in the ROM of the intervertebral disks of L5/S1 and L4/5 before and after surgery. CONCLUSIONS: The universal pedicle screw-V rod system and isthmic bone grafting directly repairs isthmic spondylolysis and reduces back pain, prevents anterior displacement of the diseased segment and maintains intervertebral space height, thus offering a promising alternative to current approaches for isthmic spondylolysis.

  19. Biomechanical effect of the iliac screw insertion depth on lumboiliac taxation construct%髂骨钉置入深度对腰椎-骨盆重建结构的生物力学影响

    Institute of Scientific and Technical Information of China (English)

    陈辉; 于滨生; 郑召民; 吕游; 张奎渤; 刘辉; 李佛保

    2008-01-01

    Objective To biomechanically compare the stability of the short and long iliae screw fixation constructs in lumboiliac reconstruction. Methods Seven adult human embalmed cadavers (L3- pelvis) were used. Using posterior spinal fixation system, L4-S1 pedicle screw fixation was performed. This was defined as intact state of the sacroiliac joint. After the intact test, total sacrum resection and L4-L5- pelvis reconstruction by pediele screw and iliac screw with different lengths were performed as follow: short screw group (as the length of exceeding 2 mm over ischial notch) and long screw group (as the length of exceeding 2 mm over anterior inferior iliac spine ). Using the 858 MTS material testing machine, biomechanical testing was performed under 800 N compression and 7 Nm torsion loading modes. At last, the axial pullout test of two iliac screws was executed. Construct stiffness in compression and torsion test, and maximum pullout force were analyzed. Results Insertion lengths of the short and long iliac screw were (70±2) mm and (138±4) mm respectively. The lumbopelvic reconstruction using short and long iliac screw, respectively restored 53.3%±13.6% and 57.6%±16.2% of the initial stiffness in compression testing, and respectively harvested 55.1%±11.9% and 62.5%±9.2% of the initial stiffness in torsion testing. No significant difference was detected between the two reconstructions (P>0.05), however, the compressive and torsional stiffness of the two techniques were markedly less than the intact condition (P0.05);但是,两者的轴向压缩及旋转刚度均显著低于完整状态组(P<0.05).髂骨长钉的最大拔出力显著高于髂骨短钉(P<0.05).结论 在生理载荷下,髂骨短钉的脊柱-骨盆重建结构可获得与髂骨长钉同等的力学稳定性;髂骨短钉的置入深度仅为长钉的一半,可降低置入的风险.但是,无论髂骨长钉或短钉的脊柱.骨盆重建装置均难以恢复局部的初始稳定性.

  20. A Biomechanical Study Comparing Helical Blade with Screw Design for Sliding Hip Fixations of Unstable Intertrochanteric Fractures

    Directory of Open Access Journals (Sweden)

    Qiang Luo

    2013-01-01

    Full Text Available Dynamic hip screw (DHS is a well-established conventional implant for treating intertrochanteric fracture. However, revision surgery sometimes still occurs due to the cutting out of implants. A helical blade instead of threaded screw (DHS blade was designed to improve the fixation power of the osteoporotic intertrochanteric fracture. In this study, the biomechanical properties of DHS blade compared to the conventional DHS were evaluated using an unstable AO/OTA 31-A2 intertrochanteric fracture model. Fifty synthetic proximal femoral bone models with such configuration were fixed with DHS and DHS blade in five different positions: centre-centre (CC, superior-centre (SC, inferior-center (IC, centre-anterior (CA, and centre-posterior (CP. All models had undergone mechanical compression test, and the vertical and rotational displacements were recorded. The results showed that DHS blade had less vertical or rotational displacement than the conventional DHS in CC, CA, and IC positions. The greatest vertical and rotational displacements were found at CP position in both groups. Overall speaking, DHS blade was superior in resisting vertical or rotational displacement in comparison to conventional DHS, and the centre-posterior position had the poorest performance in both groups.

  1. Role of rod diameter in comparison between only screws versus hooks and screws in posterior instrumentation of thoracic curve in idiopathic scoliosis.

    Science.gov (United States)

    Lamartina, Claudio; Petruzzi, Maria; Macchia, Marcello; Stradiotti, Paola; Zerbi, Alberto

    2011-05-01

    Since the introduction of Cotrel-Dubousset instrumentation in 1984, the correction techniques in scoliosis surgery have changed from Harrington principles of concave distraction to segmental realignment to a variety of possibilities including the rod rotation manoeuvres, and to segmental approximation via cantilever methods. Additionally, pedicle screw utilization in lumbar curves enhanced correction and stabilization of various deformities, and various studies have strongly supported the clinical advantages of lumbar pedicle screws versus conventional hook instrumentation. Pedicle screw constructs have become increasingly popular in the treatment of patients with spinal deformity. When applied to adolescent idiopathic scoliosis patients, pedicle screw fixation has demonstrated increased corrective ability compared with traditional hook/hybrid instrumentation. In our study, we do a retrospective review of idiopathic scoliosis patients (King 2-Lenke 1 B/C) treated with a selective thoracic posterior fusion using an all-screw construct versus a hybrid (pedicle screws and hooks) construct and, compare the percentage of correction of the scoliotic curves obtained with screws alone and screws and hooks. Special attention was given to the rod diameter and correction technique. Our results show that the percentage of correction of idiopathic thoracic scoliosis is similar when treating the scoliosis with rods and screws alone or with rods, screws and hooks; therefore, we and the majority of authors in the literature do not consider the rod section. This can be an important parameter in the evaluation of the superiority of treatment with screws only or screws and hooks. In our study, even if not of statistical significance, the better thoracic curve correction obtained with the hybrid group should be ascribed to the fact that in this group mostly 6 mm rods were used.

  2. STRUCTURE SYNTHESIS OF 4-DOF PARALLEL ROBOT MECHANISMS BASED ON SCREW THEORY

    Institute of Scientific and Technical Information of China (English)

    Fang Hairong; Fang Yuefa; Guo Sheng

    2004-01-01

    Structural synthesis for 4-DOF parallel manipulators using screw theory is systematically studied. Motion properties and constraint conditions of 4-DOF parallel manipulators according to the relationship between screw and reciprocal screw are analyzed. Mathematical expressions for constraint screws and twist screws of moving platform are constructed, and all possible limbs, which provide one or more force constraints, are enumerated. Finally, a parallel manipulator with 3-rotation-DOF and 1-translation-DOF is used as an example to describe the synthesis procedure for symmetrical and non-symmetrical 4-DOF parallel manipulators.

  3. Use of computational fluid dynamics simulations for design of a pretreatment screw conveyor reactor.

    Science.gov (United States)

    Berson, R Eric; Hanley, Thomas R

    2005-01-01

    Computational fluid dynamics simulations were employed to compare performance of various designs of a pretreatment screw conveyor reactor. The reactor consisted of a vertical screw used to create cross flow between the upward conveying solids and the downward flow of acid. Simulations were performed with the original screw design and a modified design in which the upper flights of the screw were removed. Results of the simulations show visually that the modified design provided favorable plug flow behavior within the reactor. Pressure drop across the length of the reactor without the upper screws in place was predicted by the simulations to be 5 vs 40 kPa for the original design.

  4. Effects of lag screw design and lubrication on sliding in trochanteric nails.

    Science.gov (United States)

    Kummer, Frederick J

    2010-01-01

    This study compared the sliding characteristics of three lag screw designs used with trochanteric nails and determined the effects of lubrication on sliding. They were tested by an established method to measure initiation and ease of lag screw sliding. These tests were then repeated with calf serum lubrication. There were significant differences (p Lubrication did not affect either parameter. Lag screw design aspects, such as diameter and, particularly, surface finish, affect sliding. Due to the small contact area between the lag screw and nail creating high interface stresses, lubrication had no effect on lag screw sliding.

  5. A technique for the management of screw access opening in cement-retained implant restorations

    Directory of Open Access Journals (Sweden)

    Hamid Kermanshah

    2014-01-01

    Full Text Available Introduction: Abutment screw loosening has been considered as a common complication of implant-supported dental prostheses. This problem is more important in cement-retained implant restorations due to their invisible position of the screw access opening. Case Report: This report describes a modified retrievability method for cement-retained implant restorations in the event of abutment screw loosening. The screw access opening was marked with ceramic stain and its porcelain surface was treated using hydrofluoric acid (HF, silane, and adhesive to bond to composite resin. Discussion: The present modified technique facilitates screw access opening and improves the bond between the porcelain and composite resin.

  6. Covering the screw-access holes of implant restorations in the esthetic zone: a clinical report.

    Directory of Open Access Journals (Sweden)

    Abolfazl Saboury

    2014-12-01

    Full Text Available Screw-retained implant restorations have an advantage of predictable retention as well as retrievability, and obviate the risk of excessive sub-gingival cement commonly associated with cement retained implant restorations. Screw-retained restorations generally have screw access holes, which can compromise esthetics and weaken the porcelain around the holes. The purpose of this study is to describe the use of a separate overcasting crown design to cover the screw access hole of implant screw-retained prosthesis for improved esthetics.

  7. Kinematics Analysis Based on Screw Theory of a Humanoid Robot

    Institute of Scientific and Technical Information of China (English)

    MAN Cui-hua; FAN Xun; LI Cheng-rong; ZHAO Zhong-hui

    2007-01-01

    A humanoid robot is a complex dynamic system for its idiosyncrasy. This paper aims to provide a mathematical and theoretical foundation for the design of the configuration, kinematics analysis of a novel humanoid robot. It has a simplified configuration and design for entertainment purpose. The design methods, principle and mechanism are discussed. According to the design goals of this research, there are ten degrees of freedom in the two bionic arms.Modularization, concurrent design and extension theory methods were adopted in the configuration study and screw theory was introduced into the analysis of humanoid robot kinematics. Comparisons with other methods show that: 1) only two coordinates need to be established in the kinematics analysis of humanoid robot based on screw theory; 2) the spatial manipulator Jacobian obtained by using twist and exponential product formula is succinct and legible; 3) adopting screw theory to resolve the humanoid robot arms kinematics question can avoid singularities; 4) using screw theory can solve the question of specification insufficiency.

  8. [Posterior atlantoaxial fixation using vertex multiaxial screw system].

    Science.gov (United States)

    Zhong, Dejun; Song, Yueming

    2007-06-01

    This study aims to assess the effectiveness and advantages of Vertex multiaxial screw system in use for stabilizing the atlanto-axial junction. The entry point of the atlas was located 18-20 mm lateral to the midline and 2.0 mm superior to the inferior border of posterior arch, and the direction of screw was chosen to be about 10 degrees medial to the sagittal plane and about 5 degrees cephalad to the transverse plane. In odontoid vertebra (C2), the direction of the drill bit was guided directly by the medial and superior aspect of the individual C2 pedicle. All screws were placed properly without incidence of nerve or blood vessel injury, and no complication appeared in operation and after surgery. All cases were followed up for an average of 9 months, all cases achieved well reposition and fixation of atlantoaxial joint, average JOA grade was 9.6 before preoperation and 15.9 after operation. Fixation of the atlantoaxial complex using Vertex multiaxial screw system seemed to be a reliable technique and should be considered a good alternative in atlantoaxial fusion. The technique could be used in young patiens.

  9. Kinematics of a Hybrid Manipulator by Means of Screw Theory

    Energy Technology Data Exchange (ETDEWEB)

    Gallardo-Alvarado, J [Department of Mechanical Engineering, Instituto Tecnologico de Celaya (Mexico)

    2005-11-15

    In this work the kinematics of a hybrid manipulator, namely a fully parallel-serial manipulator, with a particular topology is approached by means of the theory of screws. Given the length of the six independent limbs, the forward position analysis of the mechanism under study, indeed the computation of the resulting pose, position and orientation, of the end-platform with respect to the fixed platform, is carried out in closed-form solution. Therefore conveniently this initial analysis avoids the use of a numerical technique such as the Newton-Raphson method. Writing in screw form the reduced acceleration state of the translational platform, with respect to the fixed platform, a simple expression for the computation of the acceleration of the translational platform is derived by taking advantage of the properties of reciprocal screws, via the Klein form, a bilinear symmetric form of the Lie algebra e(3). Following a similar procedure, a simple expression for the computation of the angular acceleration of the end-platform, with respect to the translational platform, is easily derived. Naturally, as an intermediate step, this contribution also provides the forward and inverse velocity analyses of the chosen parallel-serial manipulator. Finally, in order to prove the versatility of the expressions obtained via screw theory for solving the kinematics, up to the acceleration analysis, of the proposed spatial mechanism, a numerical example is solved with the help of commercial computer codes.

  10. Optimisation of acoustic silencer for the screw compressor system

    NARCIS (Netherlands)

    Swamy, M.; Lier, L.J. van; Smeulers, J.P.M.

    2014-01-01

    In one of the screw compressor system, designed silencer was not optimal. A great challenge was the large variation in operating conditions, especially the variation of the molecular weight of the gas. There was need to optimize the silencer. This paper describes the acoustic modelling tools to opti

  11. Granulation of increasingly hydrophobic formulations using a twin screw granulator.

    Science.gov (United States)

    Yu, Shen; Reynolds, Gavin K; Huang, Zhenyu; de Matas, Marcel; Salman, Agba D

    2014-11-20

    The application of twin screw granulation in the pharmaceutical industry has generated increasing interest due to its suitability for continuous processing. However, an understanding of the impact of formulation properties such as hydrophobicity on intermediate and finished product quality has not yet been established. Hence, the current work investigated the granulation behaviour of three formulations containing increasing amounts of hydrophobic components using a Consigma™-1 twin screw granulator. Process conditions including powder feed rate, liquid to solid ratio, granulation liquid composition and screw configuration were also evaluated. The size of the wet granules was measured in order to enable exploration of granulation behaviour in isolation without confounding effects from downstream processes such as drying. The experimental observations indicated that the granulation process was not sensitive to the powder feed rate. The hydrophobicity led to heterogeneous liquid distribution and hence a relatively large proportion of un-wetted particles. Increasing numbers of kneading elements led to high shear and prolonged residence time, which acted to enhance the distribution of liquid and feeding materials. The bimodal size distributions considered to be characteristic of twin screw granulation were primarily ascribed to the breakage of relatively large granules by the kneading elements.

  12. Are inclined screw blades for vertical grain augers advantageous?

    NARCIS (Netherlands)

    Rademacher, F.J.C.

    1978-01-01

    Due to modern technology, screw blades are often manufactured by rolling them out of one single strip of steel. When simultaneously some blade inclination is applied, less residual stresses and/or larger possible ratios between outer and shaft diameter are claimed by some manufacturers, which seems

  13. 21 CFR 888.3070 - Pedicle screw spinal system.

    Science.gov (United States)

    2010-04-01

    ... treatment of the following acute and chronic instabilities or deformities of the thoracic, lumbar, and... conditions are significant mechanical instability or deformity of the thoracic, lumbar, and sacral spine... screw spinal system because this is a technically demanding procedure presenting a risk of...

  14. Residence time distribution in twin-screw extruders.

    NARCIS (Netherlands)

    Jager, T.

    1992-01-01

    For the twin-screw extruders used in the food industry at short time high temperature processes the knowledge of their reactor properties is incomplete for mass- and heat flow. Therefore each process change such as: scale-up or product development requires a great number of measurements before an ac

  15. Coupled Thermodynamic Behavior of New Screw Compressors Rotors Profile

    Directory of Open Access Journals (Sweden)

    Arístides Rivera Torres

    2010-05-01

    Full Text Available The article displays an evaluation of the thermodynamic behavior of screw compressor rotors with new profiles, obtained with the help of the Scorpath 2000 software. This allows predicting precisely the operation of the compressor, as well as its thermodynamic evaluation, under equal conditions, with the work of other compressors fitted with rotor profiles of other kinds.

  16. Sacroiliac screw fixation: A mini review of surgical technique

    Directory of Open Access Journals (Sweden)

    Hernando Raphael Alvis-Miranda

    2014-01-01

    Full Text Available The sacral percutaneous fixation has many advantages but can be associated with a significant exposure to X-ray radiation. Currently, sacroiliac screw fixation represents the only minimally invasive technique to stabilize the posterior pelvic ring. It is a technique that should be used by experienced surgeons. We present a practical review of important aspects of this technique.

  17. Sacroiliac screw fixation: A mini review of surgical technique

    Science.gov (United States)

    Alvis-Miranda, Hernando Raphael; Farid-Escorcia, Hector; Alcalá-Cerra, Gabriel; Castellar-Leones, Sandra Milena; Moscote-Salazar, Luis Rafael

    2014-01-01

    The sacral percutaneous fixation has many advantages but can be associated with a significant exposure to X-ray radiation. Currently, sacroiliac screw fixation represents the only minimally invasive technique to stabilize the posterior pelvic ring. It is a technique that should be used by experienced surgeons. We present a practical review of important aspects of this technique. PMID:25336831

  18. Ankle fusion using a 2-incision, 3-screw technique

    NARCIS (Netherlands)

    R.P.M. Hendrickx; G.M.M.J. Kerkhoffs; S.A.S. Stufkens; C.N. van Dijk; R.K. Marti

    2011-01-01

    Reliable fusion and optimal correction of the alignment of the ankle joint using a 2-incision, 3-screw technique. Symptomatic osteoarthritis of the ankle joint after insufficient other treatment, severe deformity of the osteoarthritic ankle joint, or salvation procedure after failed arthroplasty. Ac

  19. Atomistic simulations of jog migration on extended screw dislocations

    DEFF Research Database (Denmark)

    Vegge, T.; Leffers, T.; Pedersen, O.B.;

    2001-01-01

    We have performed large-scale atomistic simulations of the migration of elementary jogs on dissociated screw dislocations in Cu. The local crystalline configurations, transition paths. effective masses. and migration barriers for the jogs are determined using an interatomic potential based on the...

  20. Design of a magnetic lead screw for wave energy conversion

    DEFF Research Database (Denmark)

    Holm, Rasmus Koldborg; Berg, Nick Ilsoe; Walkusch, Morten

    2013-01-01

    This paper deals with the development of a magnetic lead screw (MLS) for wave energy conversion. Initially, a brief state of the art regarding linear permanent-magnet generators and MLSs is given, leading to an introduction of the MLS and a presentation of the results from a finite-element analysis...

  1. Radiographic measurement of key parameters used in the unilateral transpedicular approach on percutaneous kyphoplasty%单侧入路经皮椎体后凸成形术关键参数的影像学测量

    Institute of Scientific and Technical Information of China (English)

    翟伟峰; 贾永伟; 王建杰; 程黎明

    2015-01-01

    目的 探索基于影像学测量获得单侧入路经皮椎体后凸成形术的关键参数,为临床操作提供参考. 方法 随机选择我科住院患者的胸椎、腰椎CT片各120例,利用我院影像科PACS系统、Uniweb Server软件,通过模拟单侧入路经皮椎体后凸成形术的最佳穿刺路径,测出T4 ~L5 椎体穿刺路径的内倾角、尾倾角、皮肤入针点旁开棘突的距离. 并结合临床实践,验证数据的准确性. 结果 单侧穿刺途径:T4 ~T9 椎体,内倾角(24.6 ± 4.2)°,尾倾角(19.8 ±1.8)°,棘突旁开距离(3.5 ±0.5)cm. T10 ~L2 椎体,内倾角(25.6 ±4.8)°,尾倾角(18.5 ± 1.6)°,棘突旁开距离(3.8 ±0.6)cm. L3 ~L5 椎体,内倾角(34.2 ±7.8)°,尾倾角(17.5 ±1.9)°,棘突旁开距离(5.9 ±1.2) cm. 结论 基于影像学测量获得关键参数,是顺利进行单侧入路经皮椎体后凸成形术的重要依据,根据测量的数据指导临床实践,操作简便、安全,穿刺准确性高,对临床操作有一定的参考价值.%Objective To obtain the key parameters required for the unilateral transpedicular approach on percuta-neous kyphoplasty through imaging measurement, so as to provide evidence for clinical practice.Methods A total of 120 CT images of thoracic and lumbar vertebrae were randomly collected from patients in our department.Then, using the PACS system and Uniweb Server software, the angles of introvertion and declination, and the distance between the skin entry point and the spinous process from T4 to L5 were measured through imitation of percutaneous kyphoplasty via the u-nilateral transpedicular approach.Meanwhile, the accuracy of the measurement was verified on the basis of clinical prac-tice.Results The unilateral transpedicular puncture yielded an introvertion angle of (24.6 ±4.2) for T4 -T9 , (25.6 ±4.8) for T10 -L2 and (34.2 ±7.8) for L3 -L5 and a declination angle of (19.8 ±1.8) for T4 -T9, (18.5 ±1.6) for T10 -L2 and (17.5 ±1.9) for L3 -L5 .The distance

  2. Posterior and Anterior Spinal Fusion for the Management of Deformities in Patients with Parkinson's Disease

    Directory of Open Access Journals (Sweden)

    Masashi Sato

    2013-01-01

    Full Text Available Introduction. Spinal scoliosis and kyphosis in elderly people sometimes cause severe low back pain. Surgical methods such as osteotomy are useful for correcting the deformity. However, complications during and after surgery are associated with the osteotomy procedure. In particular, it is difficult to manage deformity correction surgery for patients with Parkinson's disease. Here, we present two cases of combined anterior and posterior surgery for deformity in patients with adult scoliosis and kyphosis due to Parkinson's disease. Case Presentation. Two 70-year-old women had spinal scoliosis and kyphosis due to Parkinson's disease. They had severe low back pain, and conservative treatment was not effective for the pain. Surgery was planned to correct the deformity in both patients. We performed combined posterior and anterior correction surgery. At first, posterior fusions were performed from T4 to the ilium using pedicle screws. Next, cages and autograft from the iliac crest were used in anterior lumbar surgery. The patients became symptom free after surgery. Bony fusion was observed 12 months after surgery. Conclusions. Combined posterior and anterior fusion surgery is effective for patients who show scoliosis and kyphosis deformity, and symptomatic low back pain due to Parkinson's disease.

  3. The general theory of blade screws including propellers, fans, helicopter screws, helicoidal pumps, turbo-motors, and different kinds of helicoidal blades

    Science.gov (United States)

    De Bothezat, George

    1920-01-01

    Report presents a theory which gives a complete picture and an exact quantitative analysis of the whole phenomenon of the working of blade screws, but also unites in a continuous whole the entire scale of states of work conceivable for a blade screw. Chapter 1 is devoted to the establishment of the system of fundamental equations relating to the blade screw. Chapter 2 contains the general discussion of the 16 states of work which may establish themselves for a blade screw. The existence of the vortex ring state and the whirling phenomenon are established. All the fundamental functions which enter the blade-screw theory are submitted to a general analytical discussion. The general outline of the curve of the specific function is examined. Two limited cases of the work of the screw, the screw with a zero constructive pitch and the screw with an infinite constructive pitch, are pointed out. Chapter 3 is devoted to the study of the propulsive screw or propeller. (author)

  4. A rationale method for evaluating unscrewing torque values of prosthetic screws in dental implants

    Directory of Open Access Journals (Sweden)

    Felipe Miguel Saliba

    2011-02-01

    Full Text Available OBJECTIVES: Previous studies that evaluated the torque needed for removing dental implant screws have not considered the manner of transfer of the occlusal loads in clinical settings. Instead, the torque used for removal was applied directly to the screw, and most of them omitted the possibility that the hexagon could limit the action of the occlusal load in the loosening of the screws. The present study proposes a method for evaluating the screw removal torque in an anti-rotational device independent way, creating an unscrewing load transfer to the entire assembly, not only to the screw. MATERIAL AND METHODS: Twenty hexagonal abutments without the hexagon in their bases were fixed with a screw to 20 dental implants. They were divided into two groups: Group 1 used titanium screws and Group 2 used titanium screws covered with a solid lubricant. A torque of 32 Ncm was applied to the screw and then a custom-made wrench was used for rotating the abutment counterclockwise, to loosen the screw. A digital torque meter recorded the torque required to loosen the abutment. RESULTS: There was a significant difference between the means of Group 1 (38.62±6.43 Ncm and Group 2 (48.47±5.04 Ncm, with p=0.001. CONCLUSION: This methodology was effective in comparing unscrewing torque values of the implant-abutment junction even with a limited sample size. It confirmed a previously shown significant difference between two types of screws.

  5. Bioresorbable screws reinforced with phosphate glass fibre: manufacturing and mechanical property characterisation.

    Science.gov (United States)

    Felfel, R M; Ahmed, I; Parsons, A J; Rudd, C D

    2013-01-01

    Use of bioresorbable screws could eliminate disadvantages associated with metals such as removal operations, corrosion, MRI interference and stress shielding. Mechanical properties of bioresorbable polymers alone are insufficient for load bearing applications application as screws. Thus, reinforcement is necessary to try and match or surpass the mechanical properties of cortical bone. Phosphate based glass fibres were used to reinforce polylactic acid (PLA) in order to produce unidirectionally aligned (UD) and unidirectionally plus randomly distributed (UD/RM) composite screws (P40 UD and P40 UD/RM). The maximum flexural and push-out properties for the composite screws (P40 UD and P40 UD/RM) increased by almost 100% in comparison with the PLA screws. While the pull-out strength and stiffness of the headless composite screws were ∼80% (strength) and ∼130% (stiffness) higher than for PLA, those with heads exhibited properties lower than those for PLA alone as a result of failure at the heads. An increase in the maximum shear load and stiffness for the composite screws (∼30% and ∼40%) in comparison to the PLA screws was also seen. Maximum torque for the PLA screws was ∼1000 mN m, while that for the composite screws were slightly lower. The SEM micrographs for P40 UD and P40 UD/RM screws revealed small gaps around the fibres, which were suggested to be due to buckling of the UD fibres during the manufacturing process.

  6. Screw Remaining Life Prediction Based on Quantum Genetic Algorithm and Support Vector Machine

    Directory of Open Access Journals (Sweden)

    Xiaochen Zhang

    2017-01-01

    Full Text Available To predict the remaining life of ball screw, a screw remaining life prediction method based on quantum genetic algorithm (QGA and support vector machine (SVM is proposed. A screw accelerated test bench is introduced. Accelerometers are installed to monitor the performance degradation of ball screw. Combined with wavelet packet decomposition and isometric mapping (Isomap, the sensitive feature vectors are obtained and stored in database. Meanwhile, the sensitive feature vectors are randomly chosen from the database and constitute training samples and testing samples. Then the optimal kernel function parameter and penalty factor of SVM are searched with the method of QGA. Finally, the training samples are used to train optimized SVM while testing samples are adopted to test the prediction accuracy of the trained SVM so the screw remaining life prediction model can be got. The experiment results show that the screw remaining life prediction model could effectively predict screw remaining life.

  7. Evaluation of different screw fixation techniques and screw diameters in sagittal split ramus osteotomy: finite element analysis method.

    Science.gov (United States)

    Sindel, A; Demiralp, S; Colok, G

    2014-09-01

    Sagittal split ramus osteotomy (SSRO) is used for correction of numerous congenital or acquired deformities in facial region. Several techniques have been developed and used to maintain fixation and stabilisation following SSRO application. In this study, the effects of the insertion formations of the bicortical different sized screws to the stresses generated by forces were studied. Three-dimensional finite elements analysis (FEA) and static linear analysis methods were used to investigate difference which would occur in terms of forces effecting onto the screws and transmitted to bone between different application areas. No significant difference was found between 1·5- and 2-mm screws used in SSRO fixation. Besides, it was found that 'inverted L' application was more successful compared to the others and that was followed by 'L' and 'linear' formations which showed close rates to each other. Few studies have investigated the effect of thickness and application areas of bicortical screws. This study was performed on both advanced and regressed jaws positions.

  8. Subaxial cervical pedicle screw insertion with newly defined entry point and trajectory: accuracy evaluation in cadavers.

    Science.gov (United States)

    Zheng, Xiujun; Chaudhari, Rahul; Wu, Chunhui; Mehbod, Amir A; Transfeldt, Ensor E

    2010-01-01

    Successful placement of cervical pedicle screws requires accurate identification of both entry point and trajectory. However, literature has not provided consistent recommendations regarding the direction of pedicle screw insertion and entry point location. The objective of this study was to define a guideline regarding the optimal entry point and trajectory in placing subaxial cervical pedicle screws and to evaluate the screw accuracy in cadaver cervical spines. The guideline for entry point and trajectory for each vertebra was established based on the recently published morphometric data. Six fresh frozen cervical spines (C3-C7) were used. There were two men and four women. After posterior exposure, the entry point was determined and the cortical bone of the entry point was removed using a 2-mm burr. Pilot holes were created with a cervical probe based on the guideline using fluoroscopy. After tapping, 3.5-mm screws with appropriate length were inserted. After screw insertion, every vertebra was dissected and inspected for pedicle breach. The pedicle width, height, pedicle transverse angulation and actual screw insertion angle were measured. A total of 60 pedicle screws were inserted. No statistical difference in pedicle width and height was found between the left and right sides for each level. The overall accuracy of pedicle screws was 83.3%. The remaining 13.3% screws had noncritical breach, and 3.3% had critical breach. The critical breach was not caused by the guideline. There was no statistical difference between the pedicle transverse angulation and the actual screw trajectory created using the guideline. There was statistical difference in pedicle width between the breach and non-breach screws. In conclusion, high success rate of subaxial cervical pedicle screw placement can be achieved using the recently proposed operative guideline and oblique views of fluoroscopy. However, careful preoperative planning and good surgical skills are still required to

  9. Biomechanical Evaluation of Plate Versus Lag Screw Only Fixation of Distal Fibula Fractures.

    Science.gov (United States)

    Misaghi, Amirhossein; Doan, Josh; Bastrom, Tracey; Pennock, Andrew T

    2015-01-01

    Traditional fixation of unstable Orthopaedic Trauma Association type B/C ankle fractures consists of a lag screw and a lateral or posterolateral neutralization plate. Several studies have demonstrated the clinical success of lag screw only fixation; however, to date no biomechanical comparison of the different constructs has been performed. The purpose of the present study was to evaluate the biomechanical strength of these different constructs. Osteotomies were created in 40 Sawbones(®) distal fibulas and reduced using 1 bicortical 3.5-mm stainless steel lag screw, 2 bicortical 3.5-mm lag screws, 3 bicortical 3.5-mm lag screws, or a single 3.5-mm lag screw coupled with a stainless steel neutralization plate with 3 proximal cortical and 3 distal cancellous screws. The constructs were tested to determine the stiffness in lateral bending and rotation and failure torque. No significant differences in lateral bending or rotational stiffness were detected between the osteotomies fixed with 3 lag screws and a plate. Constructs fixed with 1 lag screw were weaker for both lateral bending and rotational stiffness. Osteotomies fixed with 2 lag screws were weaker in lateral bending only. No significant differences were found in the failure torque. Compared with lag screw only fixation, plate fixation requires larger incisions and increased costs and is more likely to require follow-up surgery. Despite the published clinical success of treating simple Orthopaedic Trauma Association B/C fractures with lag screw only fixation, many surgeons still have concerns about stability. For noncomminuted, long oblique distal fibula fractures, lag screw only fixation techniques offer construct stiffness similar to that of traditional plate and lag screw fixation.

  10. Accuracy of robot-assisted pedicle screw placement for adolescent idiopathic scoliosis in the pediatric population.

    Science.gov (United States)

    Macke, Jeremy J; Woo, Raymund; Varich, Laura

    2016-06-01

    This is a retrospective review of pedicle screw placement in adolescent idiopathic scoliosis (AIS) patients under 18 years of age who underwent robot-assisted corrective surgery. Our primary objective was to characterize the accuracy of pedicle screw placement with evaluation by computed tomography (CT) after robot-assisted surgery in AIS patients. Screw malposition is the most frequent complication of pedicle screw placement and is more frequent in AIS. Given the potential for serious complications, the need for improved accuracy of screw placement has spurred multiple innovations including robot-assisted guidance devices. No studies to date have evaluated this robot-assisted technique using CT exclusively within the AIS population. Fifty patients were included in the study. All operative procedures were performed at a single institution by a single pediatric orthopedic surgeon. We evaluated the grade of screw breach, the direction of screw breach, and the positioning of the patient for preoperative scan (supine versus prone). Of 662 screws evaluated, 48 screws (7.2 %) demonstrated a breach of greater than 2 mm. With preoperative prone position CT scanning, only 2.4 % of screws were found to have this degree of breach. Medial malposition was found in 3 % of screws, a rate which decreased to 0 % with preoperative prone position scanning. Based on our results, we conclude that the proper use of image-guided robot-assisted surgery can improve the accuracy and safety of thoracic pedicle screw placement in patients with adolescent idiopathic scoliosis. This is the first study to evaluate the accuracy of pedicle screw placement using CT assessment in robot-assisted surgical correction of patients with AIS. In our study, the robot-assisted screw misplacement rate was lower than similarly constructed studies evaluating conventional (non-robot-assisted) procedures. If patients are preoperatively scanned in the prone position, the misplacement rate is further

  11. Anterior cruciate ligament - updating article.

    Science.gov (United States)

    Luzo, Marcus Vinicius Malheiros; Franciozi, Carlos Eduardo da Silveira; Rezende, Fernando Cury; Gracitelli, Guilherme Conforto; Debieux, Pedro; Cohen, Moisés

    2016-01-01

    This updating article on the anterior cruciate ligament (ACL) has the aim of addressing some of the most interesting current topics in this field. Within this stratified approach, it contains the following sections: ACL remnant; anterolateral ligament and combined intra and extra-articular reconstruction; fixation devices; and ACL femoral tunnel creation techniques.

  12. Anterior cruciate ligament - updating article

    Directory of Open Access Journals (Sweden)

    Marcus Vinicius Malheiros Luzo

    2016-08-01

    Full Text Available ABSTRACT This updating article on the anterior cruciate ligament (ACL has the aim of addressing some of the most interesting current topics in this field. Within this stratified approach, it contains the following sections: ACL remnant; anterolateral ligament and combined intra and extra-articular reconstruction; fixation devices; and ACL femoral tunnel creation techniques.

  13. Femoral and Tibial Tunnel Diameter and Bioabsorbable Screw Findings After Double-Bundle ACL Reconstruction in 5-Year Clinical and MRI Follow-up

    Science.gov (United States)

    Kiekara, Tommi; Paakkala, Antti; Suomalainen, Piia; Huhtala, Heini; Järvelä, Timo

    2017-01-01

    Background: Tunnel enlargement is frequently seen in short-term follow-up after anterior cruciate ligament reconstruction (ACLR). According to new evidence, tunnel enlargement may be followed by tunnel narrowing, but the long-term evolution of the tunnels is currently unknown. Hypothesis/Purpose: The hypothesis was that tunnel enlargement is followed by tunnel narrowing caused by ossification as seen in follow-up using magnetic resonance imaging (MRI). The purpose of this study was to evaluate the ossification pattern of the tunnels, the communication of the 2 femoral and 2 tibial tunnels, and screw absorption findings in MRI. Study Design: Case series; Level of evidence, 4. Methods: Thirty-one patients underwent anatomic double-bundle ACLR with hamstring grafts and bioabsorbable interference screw fixation and were followed with MRI and clinical evaluation at 2 and 5 years postoperatively. Results: The mean tunnel enlargement at 2 years was 58% and reduced to 46% at 5 years. Tunnel ossification resulted in evenly narrowed tunnels in 44%, in conical tunnels in 48%, and fully ossified tunnels in 8%. Tunnel communication increased from 13% to 23% in the femur and from 19% to 23% in the tibia between 2 and 5 years and was not associated with knee laxity. At 5 years, 54% of the screws were not visible, with 35% of the screws replaced by a cyst and 19% fully ossified. Tunnel cysts were not associated with worse patient-reported outcomes or knee laxity. Patients with a tibial anteromedial tunnel cyst had higher Lysholm scores than patients without a cyst (93 and 84, P = .03). Conclusion: Tunnel enlargement was followed by tunnel narrowing in 5-year follow-up after double-bundle ACLR. Tunnel communication and tunnel cysts were frequent MRI findings and not associated with adverse clinical evaluation results. PMID:28203605

  14. Válvula de uretra anterior Anterior urethral valves

    Directory of Open Access Journals (Sweden)

    Silvio Tucci Jr.

    2003-02-01

    Full Text Available Objetivo: apresentar os aspectos clínicos, diagnósticos e terapêuticos de pacientes portadores de válvula da uretra anterior. Descrição: em dois neonatos, o diagnóstico presuntivo de patologia obstrutiva do trato urinário foi sugerido pela ultra-sonografia realizada no período pré-natal, confirmando-se o diagnóstico de válvula de uretra anterior pela avaliação pós-natal. Os pacientes foram submetidos a tratamento cirúrgico paliativo, com vesicostomia temporária e, posteriormente, definitivo, pela fulguração endoscópica das válvulas. Ambos evoluíram com função renal normal. Comentários: a válvula da uretra anterior é anomalia rara que deve ser considerada em meninos com quadro radiológico pré-natal sugestivo de obstrução infravesical, secundariamente à hipótese mais comum de válvula da uretra posterior. Ressaltamos a utilização da vesicostomia como derivação urinária temporária nestes casos, prevenindo potenciais complicações pela manipulação da uretra do recém-nascido.Objective: to discuss clinical signs, diagnostic tools and therapeutics of anterior urethral valves, an obstructive anomaly of the urinary system in males. Description: signs of urinary tract obstruction were identified on pre-natal ultrasound in two male fetuses and the diagnosis of anterior urethral valves was made through post-natal evaluation. As an initial treatment, vesicostomy was performed in both patients. Later, the valves were fulgurated using an endoscopic procedure. During the follow-up period both patients presented normal renal function. Comments: anterior urethral valves are a rare form of urethral anomaly that must be ruled out in boys with pre-natal ultrasound indicating infravesical obstruction. Vesicostomy used as an initial treatment rather than transurethral fulguration may prevent potential complications that can occur due to the small size of the neonatal urethra.

  15. Study of technical parameters of C1 lateral screws placement in Jefferson-fracture reduction plate%寰椎骨折前路复位内固定钢板置钉参数研究

    Institute of Scientific and Technical Information of China (English)

    夏虹; 林宏衡; 许国庆; 何小华; 尹庆水; 王智运; 许俊杰

    2012-01-01

    Objective To clarify the technical parameters of Cl lateral mass screw in anterior Jefferson-fracture reduction plate. Methods Anatomic structure of Cl lateral mass using 1-mm CT scans were measured with MIMICS software in 80 Cl lateral mass of 40 cases. 2 entry points were selected for superior and inferior screw placement and screws (2.5mm in diameter) , and simulation procedure was performed at these entry, points. Length, angle of screw and relation with adjacent anatomical structures were recorded. Results Distance from medial wall of vertebral artery hole to midline of atlas was 23.2 mm. Distance between medial wall of posterior arch junction with lateral mass and midline was 13.2 mm, and from entry point of superior screw to anterior edge of superior articular and midline were 6.2mm, 20.0mm respectively. The length of superior screw was 21.5 mm and the range of sagittal angulation was upward 1.5° to downward 11.6°. Distance from entry point of inferior screw to anterior edge of inferior articular was 8.9mm. Length of inferior screw was 15.2mm. The largest downward angulation for inferior screw was 20.7°. Distance from medial wall of vertebral hole to inferior screw was 1.9mm. The area of lateral mass (17.6~23.2) mm away from midline of atlas is relative safe for screw placement. Conclusions It is feasible to place C1 lateral mass screws (superior and inferior screw) in anterior Jefferson-fracture reduction plate. Making final decision of entry points and screw direction must depend on preoperative 3-dimensional CT evaluation. According to our research, the angulation of superior screw below turn to downward, and the angulation of inferior screw turn to inside were recommended.%目的 明确寰椎骨折前路复位内固定钢板寰椎侧块置钉可行性及置钉技术参数. 方法 用Mimics软件,对40例被检查者的CT数据进行三维重建,解剖测量,并模拟置入寰椎侧块螺钉,测量并获得置钉的技术参数.结果 椎

  16. Comparison of migration behavior between single and dual lag screw implants for intertrochanteric fracture fixation

    Directory of Open Access Journals (Sweden)

    Katonis Pavlos G

    2009-05-01

    Full Text Available Abstract Background Lag screw cut-out failure following fixation of unstable intertrochanteric fractures in osteoporotic bone remains an unsolved challenge. This study tested if resistance to cut-out failure can be improved by using a dual lag screw implant in place of a single lag screw implant. Migration behavior and cut-out resistance of a single and a dual lag screw implant were comparatively evaluated in surrogate specimens using an established laboratory model of hip screw cut-out failure. Methods Five dual lag screw implants (Endovis, Citieffe and five single lag screw implants (DHS, Synthes were tested in the Hip Implant Performance Simulator (HIPS of the Legacy Biomechanics Laboratory. This model simulated osteoporotic bone, an unstable fracture, and biaxial rocking motion representative of hip loading during normal gait. All constructs were loaded up to 20,000 cycles of 1.45 kN peak magnitude under biaxial rocking motion. The migration kinematics was continuously monitored with 6-degrees of freedom motion tracking system and the number of cycles to implant cut-out was recorded. Results The dual lag screw implant exhibited significantly less migration and sustained more loading cycles in comparison to the DHS single lag screw. All DHS constructs failed before 20,000 cycles, on average at 6,638 ± 2,837 cycles either by cut-out or permanent screw bending. At failure, DHS constructs exhibited 10.8 ± 2.3° varus collapse and 15.5 ± 9.5° rotation around the lag screw axis. Four out of five dual screws constructs sustained 20,000 loading cycles. One dual screw specimens sustained cut-out by medial migration of the distal screw after 10,054 cycles. At test end, varus collapse and neck rotation in dual screws implants advanced to 3.7 ± 1.7° and 1.6 ± 1.0°, respectively. Conclusion The single and double lag screw implants demonstrated a significantly different migration resistance in surrogate specimens under gait loading simulation with

  17. Cytotoxicity of a new antimicrobial coating for surgical screws: an in vivo study

    Science.gov (United States)

    Güzel, Yunus; Elmadag, Mehmet; Uzer, Gokcer; Yıldız, Fatih; Bilsel, Kerem; Tuncay, İbrahim

    2017-01-01

    INTRODUCTION The risk of surgery-related infection is a persistent problem in orthopaedics and infections involving implants are particularly difficult to treat. This study explored the responses of bone and soft tissue to antimicrobial-coated screws. We investigated whether such screws, which have never been used to fix bony tissues, would result in a cytotoxic effect. We hypothesised that the coated screws would not be toxic to the bone and that the likelihood of infection would be reduced since bacteria are not able to grow on these screws. METHODS Titanium screws were inserted into the left supracondylar femoral regions of 16 rabbits. The screws were either uncoated (control group, n = 8) or coated with a polyvinylpyrrolidone-polyurethane interpolymer with tertiary amine functional groups (experimental group, n = 8). At Week 6, histological samples were obtained and examined. The presence of necrosis, fibrosis and inflammation in the bony tissue and the tissue surrounding the screws was recorded. RESULTS Live, cellular bone marrow was present in all the rabbits from the experimental group, but was replaced with connective tissue in four rabbits from the control group. Eight rabbits from the control group and two rabbits from the experimental group had necrosis in fatty bone marrow. Inflammation was observed in one rabbit from the experimental group and five rabbits from the control group. CONCLUSION Titanium surgical screws coated with polyvinylpyrrolidone-polyurethane interpolymer were associated with less necrosis than standard uncoated screws. The coated screws were also not associated with any cytotoxic side effect. PMID:26805670

  18. PROSPECTS OF USE OF RELATIVE SCREW AND COMBINED REELS FOR MIXING BULKS

    Directory of Open Access Journals (Sweden)

    Marchenko A. Y.

    2015-11-01

    Full Text Available The article reveals a possibility of using equipment based on relative screw and combined drums for mixing of bulks. Change of relative positioning of flat elements of sidewalls of internal surfaces in relative screw drums allows operating the difficult and spatial movement of streams of bulks. In relative screw drums we have developed effective processes of mixing and sets of the equipment, which are characterized by that fact the difficult and spatial screw movement taking place in relative screw drums is dismembered on rather simple, in the kinematic relation, in the movements. The difficult and spatial screw movement with a big amplitude of 15-1000 mm and more, in the offered equipment constructions on the basis of relative screw or combined drums, is reported to bulks by elements of the relative screw or combined drums of various parameters and configurations which becomes complicated also screw lines on perimeter of a relative screw drum with various number of calling and the directions from each other or rounds of the springs fixed in the relative combined drums

  19. SU-E-T-609: Perturbation Effects of Pedicle Screws On Radiotherapy Dose Distributions

    Energy Technology Data Exchange (ETDEWEB)

    Bar-Deroma, R; Borzov, E; Nevelsky, A [Rambam Medical Center, Haifa (Israel)

    2015-06-15

    Purpose: Radiation therapy in conjunction with surgical implant fixation is a common combined treatment in case of bone metastases. However, metal implants generally used in orthopedic implants perturb radiation dose distributions. Carbon-Fiber Reinforced (CFR) PEEK material has been recently introduced for production of intramedullary screws and plates. Gold powder can be added to the CFR-PEEK material in order to enhance visibility of the screws during intraoperative imaging procedures. In this work, we investigated the perturbation effects of the pedicle screws made of CFR-PEEK, CFR-PEEK with added gold powder (CFR-PEEK-AU) and Titanium (Ti) on radiotherapy dose distributions. Methods: Monte Carlo (MC) simulations were performed using the EGSnrc code package for 6MV beams with 10×10 fields at SSD=100cm. By means of MC simulations, dose distributions around titanium, CFR- PEEK and CFR-PEEK-AU screws (manufactured by Carbo-Fix Orthopedics LTD, Israel) placed in a water phantom were calculated. The screw axis was either parallel or perpendicular to the beam axis. Dose perturbation (relative to dose in homogeneous water phantom) was assessed. Results: Maximum overdose due to backscatter was 10% for the Ti screws, 5% for the CFR-PEEK-AU screws and effectively zero for the CFR-PEEK screws. Maximum underdose due to attenuation was 25% for the Ti screws, 15% for the CFR-PEEK-AU screws and 5% for the CFR-PEEK screws. Conclusion: Titanium screws introduce the largest distortion on the radiation dose distribution. The gold powder added to the CFR-PEEK material improves visibility at the cost of increased dose perturbation. CFR-PEEK screws caused minimal alteration on the dose distribution. This can decrease possible over and underdose of adjacent tissue and thus favorably influence treatment efficiency. The use of such implants has potential clinical advantage in the treatment of neoplastic bone disease.

  20. Determination of Screw and Nail Withdrawal Resistance of Some Important Wood Species

    Directory of Open Access Journals (Sweden)

    Alper Aytekin

    2008-04-01

    Full Text Available In this study, screw and nail withdrawal resistance of fir (Abies nordmanniana, oak (Quercus robur L. black pine (Pinus nigra Arnold and Stone pine (Pinus pinea L. wood were determined and compared. The data represent the testing of withdrawal resistance of three types of screws as smart, serrated and conventional and common nails. The specimens were prepared according to TS 6094 standards. The dimensions of the specimens were 5x5x15cm and for all of the directions. Moreover, the specimens were conditioned at ambient room temperature and 65±2% relative humidity. The screws and nails were installed according to ASTM-D 1761 standards. Nail dimensions were 2.5mm diameter and 50 mm length, conventional screws were 4x50mm, serrated screws were 4x45mm and smart screws were 4x50mm. Results show that the maximum screw withdrawal resistance value was found in Stone pine for the serrated screw. There were no significant differences between Stone pine and oak regarding screw withdrawal resistance values. Conventional screw yielded the maximum screw withdrawal resistance value in oak, followed by Stone pine, black pine and fir. Oak wood showed the maximum screw withdrawal resistance value for the smart screw, followed by Stone pine, black pine, and fir. Oak wood showed higher nail withdrawal resistances than softwood species. It was also determined that oak shows the maximum nail withdrawal resistance in all types. The nail withdrawal resistances at the longitudinal direction are lower with respect to radial and tangential directions.

  1. Adjacent level spondylodiscitis after anterior cervical decompression and fusion

    Directory of Open Access Journals (Sweden)

    Saumyajit Basu

    2012-01-01

    Full Text Available Postoperative spondylodiscitis after anterior cervical decompression and fusion (ACDF is rare, but the same occurring at adjacent levels without disturbing the operated level is very rare. We report a case, with 5 year followup, who underwent ACDF from C5 to C7 for cervical spondylotic myelopathy. He showed neurological improvement after surgery but developed discharging sinus after 2 weeks, which healed with antibiotics. He improved on his preoperative symptoms well for the first 2 months. He started developing progressive neck pain and myelopathy after 3 months and investigations revealed spondylodiscitis at C3 and C4 with erosion, collapse, and kyphosis, without any evidence of implant failure or graft rejection at the operated level. He underwent reexploration and implant removal at the operated level (there was good fusion from C5 to C7 followed by debridement/decompression at C3, C4 along with iliac crest bone grafting and stabilization with plate and screws after maximum correction of kyphosis. The biopsy specimen grew Pseudomonas aeruginosa and appropriate sensitive antibiotics (gentamycin and ciprofloxacin were given for 6 weeks. He was under regular followup for 5 years his myelopathy resolved completely and he is back to work. Complete decompression of the cord and fusion from C2 to C7 was demonstrable on postoperative imaging studies without any evidence of implant loosening or C1/C2 instability at the last followup.

  2. Fenestration of the anterior cerebral artery

    Energy Technology Data Exchange (ETDEWEB)

    Ito, J.; Washiyama, K.; Hong, K.C.; Ibuchi, Y.

    1981-08-01

    Three cases of angiographically demonstrated fenestration of the anterior cerebral artery are reported. Fenestration occurred at the medial half of the horizontal segment of the anterior cerebral artery in all cases. Its embryology and clinical significance are briefly discussed, and the anatomical and radiological literature on fenestration of the anterior cerebral artery is reviewed.

  3. 38 CFR 3.379 - Anterior poliomyelitis.

    Science.gov (United States)

    2010-07-01

    ... 38 Pensions, Bonuses, and Veterans' Relief 1 2010-07-01 2010-07-01 false Anterior poliomyelitis. 3... Specific Diseases § 3.379 Anterior poliomyelitis. If the first manifestations of acute anterior poliomyelitis present themselves in a veteran within 35 days of termination of active military service, it...

  4. Epidermoid cyst in Anterior, Middle

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    Kankane Vivek Kumar

    2016-09-01

    Full Text Available Epidermoid cysts are benign slow growing more often extra-axial tumors that insinuate between brain structures, we present the clinical, imaging, and pathological findings in 35 years old female patients with atypical epidermoid cysts which was situated anterior, middle & posterior cranial fossa. NCCT head revealed hypodense lesion over right temporal and perisylvian region with extension in prepontine cistern with mass effect & midline shift and MRI findings revealed a non-enhancing heterogeneous signal intensity cystic lesion in right frontal & temporal region extending into prepontine cistern with restricted diffusion. Patient was detoriated in night of same day of admission, emergency Fronto-temporal craniotomy with anterior peterousectomy and subtotal resection was done. The histological examination confirms the epidermoid cyst. The timing of ectodermal tissue sequestration during fetal development may account for the occurrence of atypical epidermoid cysts.

  5. Modeling the Parker instability in a rotating plasma screw pinch

    CERN Document Server

    Khalzov, I V; Katz, N; Forest, C B; 10.1063/1.3684240

    2012-01-01

    We analytically and numerically study the analogue of the Parker (magnetic buoyancy) instability in a uniformly rotating plasma screw pinch confined in a cylinder. Uniform plasma rotation is imposed to create a centrifugal acceleration, which mimics the gravity required for the classical Parker instability. The goal of this study is to determine how the Parker instability could be unambiguously identified in a weakly magnetized, rapidly rotating screw pinch, in which the rotation provides an effective gravity and a radially varying azimuthal field is controlled to give conditions for which the plasma is magnetically buoyant to inward motion. We show that an axial magnetic field is also required to circumvent conventional current driven magnetohydrodynamic (MHD) instabilities such as the sausage and kink modes that would obscure the Parker instability. These conditions can be realized in the Madison Plasma Couette Experiment (MPCX). Simulations are performed using the extended MHD code NIMROD for an isothermal...

  6. Analysis of Eyring-Powell Fluid in Helical Screw Rheometer

    Directory of Open Access Journals (Sweden)

    A. M. Siddiqui

    2014-01-01

    Full Text Available This paper aims to study the flow of an incompressible, isothermal Eyring-Powell fluid in a helical screw rheometer. The complicated geometry of the helical screw rheometer is simplified by “unwrapping or flattening” the channel, lands, and the outside rotating barrel, assuming the width of the channel is larger as compared to the depth. The developed second order nonlinear differential equations are solved by using Adomian decomposition method. Analytical expressions are obtained for the velocity profiles, shear stresses, shear at wall, force exerted on fluid, volume flow rates, and average velocity. The effect of non-Newtonian parameters, pressure gradients, and flight angle on the velocity profiles is noticed with the help of graphical representation. The observation confirmed the vital role of involved parameters during the extrusion process.

  7. Analysis of Eyring-Powell fluid in helical screw rheometer.

    Science.gov (United States)

    Siddiqui, A M; Haroon, T; Zeb, M

    2014-01-01

    This paper aims to study the flow of an incompressible, isothermal Eyring-Powell fluid in a helical screw rheometer. The complicated geometry of the helical screw rheometer is simplified by "unwrapping or flattening" the channel, lands, and the outside rotating barrel, assuming the width of the channel is larger as compared to the depth. The developed second order nonlinear differential equations are solved by using Adomian decomposition method. Analytical expressions are obtained for the velocity profiles, shear stresses, shear at wall, force exerted on fluid, volume flow rates, and average velocity. The effect of non-Newtonian parameters, pressure gradients, and flight angle on the velocity profiles is noticed with the help of graphical representation. The observation confirmed the vital role of involved parameters during the extrusion process.

  8. HA/UHMWPE Nanocomposite Produced by Twin-screw Extrusion

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    The HA/UHMWPE nanocomposite is compounded by twin-screw extrusion of the HA and UHMWPE powder mixture in paraffin oil and then compression molded to a sheet form. TGA measurement shows the HA weight loss after processing is about 1%-2% . FTIR spectra indicate the paraffin oil residue is trivial and UHMWPE is not oxidized. SEM reveals the HA nano particles are homogeneously dispersed by twin- screw extrusion and the inter-particle spaces are penetrated with UHMWPE fibrils by swelling treatment. HRTEM image indicates the HA particles and UHMWPE are intimately contacted by mechanical interlocking. Compared with the unfilled UHMWPE, stiffness of the composite with the HA volume fraction 0.23 was significantly enhanced to 9 times without detriment of the yield strength and the ductility.

  9. Numerical Simulation and Performance Analysis of Twin Screw Air Compressors

    Directory of Open Access Journals (Sweden)

    W. S. Lee

    2001-01-01

    Full Text Available A theoretical model is proposed in this paper in order to study the performance of oil-less and oil-injected twin screw air compressors. Based on this model, a computer simulation program is developed and the effects of different design parameters including rotor profile, geometric clearance, oil-injected angle, oil temperature, oil flow rate, built-in volume ratio and other operation conditions on the performance of twin screw air compressors are investigated. The simulation program gives us output variables such as specific power, compression ratio, compression efficiency, volumetric efficiency, and discharge temperature. Some of the above results are then compared with experimentally measured data and good agreement is found between the simulation results and the measured data.

  10. Accuracy of spinal navigation for Magerl-screws

    CERN Document Server

    Herz, T

    2001-01-01

    Study design: assessment of the accuracy of frameless stereotactic navigation at the second cervical vertebra. Objectives: to assess the influence of the protocol of preoperative CT-scan and the registration technique on the accuracy of navigation for implanting Magerl-screws. Summary of background data: the use of navigation systems for implanting Magerl-screws could help to decrease the risk of complications and to reduce the required skin incision. Two parameters conceivably affecting the accuracy are the protocol of the preoperative CT-scan and the registration technique. Methods: four cervical spine segments of human cadavers were scanned with two different protocols (3 mm slice thickness/2 mm table increment, 1 mm slice thickness/1 mm table increment). Registration was performed either based on anatomical landmarks or using a specially designed percutaneous registration device. For the accuracy-check, the pointer tip was exactly placed on markers. The distance between the pointer and the marker displaye...

  11. Twin screw two-phase expanders in large chiller units

    Energy Technology Data Exchange (ETDEWEB)

    Smith, I.K.; Stosic, N.; Aldis, C.A.; Kovacevic, A. [City Univ., Dept. of Mechanical Engineering and Aeronautics, London (United Kingdom)

    1999-07-01

    An investigation was carried out to determine the feasibility of the use of a twin screw expander as a throttle valve replacement in a 500 ton chiller. The aim was to produce a demonstration unit with an overall machine adiabatic efficiency of not less that 70%. The efficiency target was effectively met but further analytical work is needed to predict mass flow rates reliably and hence the exact machine size required when refrigerant enters the expander as subcooled liquid. (Author)

  12. The human sacrum and safe approaches for screw placement.

    Science.gov (United States)

    Arman, Candan; Naderi, Sait; Kiray, Amaç; Aksu, Funda Taştekin; Yilmaz, Hakan Sinan; Tetik, Süleyman; Korman, Esin

    2009-08-01

    The human sacrum is the target of lumbosacral instrumentation and decompression procedures. Such surgical interventions require detailed knowledge of the anatomy of the human sacrum. The aim of this study was to measure surgically relevant parameters. Several factors, including the one-piece composition of the sacrum, the angles of the sacral pedicles and the anteroposterior diameter of the sacral vertebral bodies distinguish the sacrum from other parts of spine. Thirty-two measurements of shape, angles and distances between parts were taken of the sacra of 100 adult West Anatolian people using a Vernier caliper accurate to 0.1 mm and goniometer. According to this morphometric study, when measured from the sagittal, the S1 facet angle was measured as 35.71 degrees +/-9.59 and 34.70 degrees +/-9.66, the sacral pedicle anteromedial screw trajectory angle was 35.65 degrees +/-4.73 and 31.95 degrees +/-3.95 and the anterolaterally oriented sacral wing screw trajectory angle was 32.65 degrees +/-3.51 and 29.10 degrees +/-3.14, on the right and left sides, respectively. The distance of the midline oriented S1 pedicle screw was 51.12 mm and 51.26 mm on the right and left side, respectively. The distance for sacral wing oriented screw placement was 50.13 mm and 50.46 mm on the right and left side, respectively. The anteroposterior and transverse diameter of the sacral spinal canal were 21.81 mm and 31.31 mm, respectively. Thus, this study describes anatomical specifications of the sacrum. These defined morphometric details should be taken into consideration during surgical procedures. This study also describes anatomical landmarks which will allow injury of the sacrum during surgery to be avoided.

  13. Fluid Flow Phenomenon in a Three-Bladed Power-Generating Archimedes Screw Turbine

    Directory of Open Access Journals (Sweden)

    Tineke Saroinsong

    2016-05-01

    Full Text Available Experimental studies of the Archimedes screw turbine are applied as a micro hydro power plant for low head focused on the fluid flow. Fluid flow on a screw turbine is not completely filled water flow there is still a free surface between the water fluid and atmospheric air. Except the screw geometry, the turbine screw free surface allows the flow phenomena that are important in the process of turbine screw power generation. The Archimedes screw turbine main driving force is the fluid-gravity weight, which is affected by the inflow depth, inflow velocity and the turbine shaft’s slope. The dimensionless parameter Froude number (Fr is connected to analyze the screw turbine efficiency. The purpose of this study is to figure out the fluid flow role when power generated by a three blades Archimedes screw turbine observed visualized, and also observed the turbine rotation and torque. The observed parameters are varied in inflow depth as the characteristic length (y of Froude Number, inflow velocity (co, and the turbine shaft slope (α. The screw turbine model, were made under a laboratory scale and made from acrylic material. The geometric form is the three bladed screws which have seven screw respectively, the number of helix turns is 21, the angle of screw blade is 30°, radius ratio of 0.54 with a pitch distance of 2,4 Ro. The result from this study revealed a phenomenon of fluid flow between the screw blades a whirlpool wave occurs or vortex due to the linear momentum in a form of the hydrostatic force against the blade screw which occurs in two opposite directions and the effect of the turbine shaft angular momentum. The vortex would affect the screw turbine power generation process as most of the kinetic energy that goes into the screw turbine sucked into the vortex between the screw blades, but this phenomenon can be reduced by reducing the turbine shaft slope. The highest turbine efficiency of 89% occurred in the turbine shaft’s slope of 25

  14. 腰椎椎弓根楔形截骨术治疗强直性脊柱炎后凸畸形%Transpedicular lumbar wedge resection osteotomy for correction of kyphosis in ankyiosing spondylitis

    Institute of Scientific and Technical Information of China (English)

    范建平; 王传锋; 朱晓东; 陈家瑜; 李超; 陈超; 梁楠; 白玉树; 李明

    2013-01-01

    目的 探讨腰椎椎弓根楔形截骨术治疗强直性脊柱炎后凸畸形的临床疗效.方法 2005年1月至2010年3月,第二军医大学长海医院骨科共收治32例强直性脊柱炎后凸畸形患者,均行一期后路经腰椎椎弓根楔形截骨矫形内固定术.其中27例患者行单节段椎弓根楔形截骨术,5例患者行双节段椎弓根截骨术.术前及术后随访时拍摄脊柱全长X线片,测量影像学参数,并填写中文版脊柱侧凸研究学会22项(SRS-22)量表进行患者的健康生存质量评价.结果 手术时间平均为(260±42) min,术中出血平均(1 360±282) mL,平均随访(31±8)个月(24~76个月),均未出现神经系统并发症及假关节.患者颌眉角、全脊柱后凸角、胸腰段后凸角、腰椎前凸角由术前(65.9±11.6)°、(78.2±15.9)°、(38.9±10.3)°、(14.6±17.3)°分别矫正至术后(11.7±4.7)°、(38.9±10.3)°、(1.3±7.8)°、(26.2±5.6)°;身高和矢状面失平衡距离由术前的(135.4±15.2) cm、(37.2±11.3) cm分别矫正至术后的(166.2±9.6) cm、(12.7±7.7) cm,差异均有统计学意义(P<0.01).SRS-22评分由术前平均(1.8±0.4)改善至术后(4.0±0.6),疗效满意.结论 腰椎椎弓根楔形截骨术治疗强直性脊柱炎后凸畸形安全可靠,可获得满意的临床效果.%Objective To explore the clinical efficacies of transpedicular lumbar wedge resection osteotomy for correction of kyphosis in ankylosing spondylitis. Methods From January 2005 to March 2010,32 patients with ankylosing spondylitis kyphotic deformity received one stage posterior transpedicular wedge osteotomy and internal fixation, with 27 receiving single-level ones and 5 receiving two-level ones. All patients underwent X ray examination of the total spine to obtain radiographic parameters and were asked to accomplish simplified Chinese scoliosis research society-22 (SRS-22) questionnaire to assess quality of health before and after operation. Results The mean operation time

  15. Avaliação biomecânica da influência do macheamento e do desenho dos parafusos cervicais Biomechanical evaluation of the influence of cervical screws tapping and design

    Directory of Open Access Journals (Sweden)

    Patrícia Silva

    2009-10-01

    Full Text Available OBJETIVO: Avaliar a influência do desenho do parafuso (autoperfurante e automacheante e do macheamento do orifício-piloto sobre o torque de inserção e a força de arrancamento dos parafusos utilizados para a fixação anterior da coluna cervical. MÉTODO: Quarenta parafusos automacheantes e 20 autoperfurantes foram inseridos em 10 modelos artificiais de osso (blocos de poliuretana e 10 vértebras cervicais de carneiro. Os parâmetros estudados foram o torque de inserção e a força de arrancamento. Foram formados três grupos experimentais de acordo com o tipo de preparo do orifício- piloto e o tipo de parafuso utilizado: grupo I - parafuso automacheante com orifício- piloto perfurado e macheado; grupo II - parafuso automacheante com orifício perfurado e não macheado; grupo III - parafuso autoperfurante sem perfuração prévia do orifício- piloto e sem o macheamento. Nos grupos I e II a perfuração do orifício-piloto foi realizada por meio de broca de 3mm de diâmetro e o macheamento, com 4mm. O torque de inserção foi mensurado durante a implantação dos parafusos e, em seguida, foram realizados ensaios mecânicos em máquina universal de testes para avaliar a força de arrancamento dos parafusos. RESULTADOS: O macheamento e a perfuração do orifício- piloto reduziram significativamente o torque de inserção e a força de arrancamento. CONCLUSÃO: O torque de inserção e a força de arrancamento dos parafusos autoperfurantes foram significativamente maiores quando comparado com os dos parafusos automacheantes inseridos após o macheamento do orifício-piloto.OBJECTIVE: To assess if the screw design (self-drilling/self-tapping and the pilot hole tapping could affect the insertion torque and screw pullout strength of the screw used in anterior fixation of the cervical spine. METHODS: Forty self-tapping screws and 20 self-drilling screws were inserted into 10 models of artificial bone and 10 cervical vertebrae of sheep. The

  16. INVESTIGATION ON KANE DYNAMIC EQUATIONS BASED ON SCREW THEORY FOR OPENCHAIN MANIPULATORS

    Institute of Scientific and Technical Information of China (English)

    LIU Wu-fa; GONG Zhen-bang; WANG Qin-que

    2005-01-01

    First, screw theory, product of exponential formulas and Jacobian matrix are introduced. Then definitions are given about active force wrench, inertial force wrench, partial velocity twist, generalized active force, and generalized inertial force according to screw theory. After that Kane dynamic equations based on screw theory for open-chain manipulators have been derived. Later on how to compute the partial velocity twist by geometrical method is illustrated. Finally the correctness of conclusions is verified by example.

  17. 3D CFD analysis of an oil injected twin screw expander

    OpenAIRE

    Papeš, Iva; Degroote, Joris; Vierendeels, Jan

    2014-01-01

    Small scale Organic Rankine Cycle (ORC) systems have a big potential for waste heat recovery in the market. Due to the smaller volume flows inside these systems, non-conventional expansion technologies such as screw expanders become more interesting. Recent economic studies have shown the important role of screw machines in such cycles. However, in order to get a better understanding of the expansion behaviour in an ORC, appropriate simulation models of screw expanders are necessary. The flow...

  18. Screw in the aorta: minimally invasive graft replacement for chronic aortic erosion by spinal instrument.

    Science.gov (United States)

    Fukuda, Wakako; Aoki, Chikashi; Daitoku, Kazuyuki; Taniguchi, Satoshi; Fukuda, Ikuo

    2013-01-01

    Intra-and early post-operative aortic injury by pedicle screw is not a rare complication in orthopedic surgery, but aortic penetration by a screw head over a long time period is considered as an uncommon case. There are various surgical management options for thoracic aortic injury caused by malpositioned spinal instruments. We report a case of a patient who underwent minimally invasive graft replacement of the descending thoracic artery for pedicle screw penetration.

  19. Twin screw wet granulation: the study of a continuous twin screw granulator using Positron Emission Particle Tracking (PEPT) technique.

    Science.gov (United States)

    Lee, Kai T; Ingram, Andy; Rowson, Neil A

    2012-08-01

    In this paper, Positron Emission Particle Tracking (PEPT) techniques are utilised to track the trajectory of single particles through the mixing and conveying zones of a Twin Screw Granulator (TSG). A TSG consisting of conveying zones and mixing zones is used in this study. The mixing zones are arranged with kneading discs at an angle of 30°, 60° or 90°. Experiments were carried out using different mixing configurations with various screw speed and total mass flow rate. The PEPT data obtained were then utilised to obtain the residence time distribution (RTD) and the Peclet number in an attempt to gain some insight into the mixing of the process. The fill level of the granulator was also estimated to study the mechanism of granulation. As might be expected, it was shown that the residence time of the granulation process increases with decreasing screw speed. It also increases with increasing angle of the arrangement of kneading blocks in the mixing zones, but will decreases when powder feed rate is increased. The fill level of the mixing zone in particular increases when the screw speed decreases or when powder feed rate increases. Furthermore, the fill level of the granulator will increase when the mixing zone configuration changes from 30° to 90°. It is shown that the granulator is never fully filled, even using 90° mixer elements implying limited compaction which may explain why the granules produced are porous compared with those from a high shear mixer. Interestingly, the RTD analysis reveals that the extent of axial mixing in the mixing zone of the granulator does not change significantly for different configurations and process conditions. There is evidence of a tail in the RTD which implies some material hold up and channelling.

  20. Postoperative evaluation of the position of interference screws, boneblocks and ligamentum patellae autografts in anterlor cruciate ligament replacement; Evaluierung von Knochenblockposition, Interferenzschraubenlage und Ersatzplastik des vorderen Kreuzbandes nach Ligamentum patellae-Transplantat mittels CT

    Energy Technology Data Exchange (ETDEWEB)

    Bauer, R, [Leipzig Univ. (Germany). FUSt 8/Radiologie; Kolbus, F.; Brueckner, B. [Leipzig Univ. (Germany). Abt. 2/Chirurgie des Bundeswehrkrankenhauses Leipzig

    2000-06-01

    Purpose: Evaluation of arthroscopically assisted reconstruction of the anterior cruciate ligament using ligamentum patellae autografts in the bone-tendon-bone technique with special regard to the position of blocks and interference screws. Material and methods: In a prospective study 28 patients were included after undergoing arthroscopic anterior cruciate ligament replacement surgery. Data thus obtained were correlated with the postoperatively determined functional parameters of the affected joint. Results: Interference screws, bone-blocks and ligamentous transplants could be well imaged using CT. In a comparison of our data with clinical results there was a statistically highly significant correlation between clinical outcome and the position of bone-blocks and interference screws in the tibia. Angles between screw and bone-block exceeding a standard deviation led to significantly worse results, while a divergence in femoral angles did not lead to significantly worse results. (orig./AJ) [German] Ziel: Evaluation der arthroskopischen Ersatzplastik des vorderen Kreuzbandes unter besonderer Beruecksichtigung der Lage der Knochenbloecke, Interferenzschrauben und Bohrkanaele mittels CT und Vergleich der radiologischen Daten mit klinischen und funktionellen Parametern. Material und Methodik: In einer prospektiven Studie wurden 28 Patienten nach arthroskopischer Ersatzplastik des vorderen Kreuzbandes mittels Lig. patellae-Transplantat im CT untersucht. Anschliessend erfolgte die Pruefung der Korrelation mit postoperativ erhobenen klinisch-funktionellen Parametern des Kniegelenks. Ergebnisse: Die Interferenzschrauben, Bohrkanaele und Knochenbloecke sowie das Transplantat konnten in allen Faellen gut dargestellt werden. Bei einem Vergleich unserer Daten mit den klinischen Untersuchungsergebnissen der Chirurgen zeigte sich ein statistisch hochsignifikanter Zusammenhang mit den Winkeldivergenzen zwischen Interferenzschraube und Bohrkanal im Bereich der Tibia. Divergenzen

  1. Biomechanical Evaluation of Different Fixation Methods for Mandibular Anterior Segmental Osteotomy Using Finite Element Analysis, Part One: Superior Repositioning Surgery.

    Science.gov (United States)

    Kilinç, Yeliz; Erkmen, Erkan; Kurt, Ahmet

    2016-01-01

    The aim of the current study was to comparatively evaluate the mechanical behavior of 3 different fixation methods following various amounts of superior repositioning of mandibular anterior segment. In this study, 3 different rigid fixation configurations comprising double right L, double left L, or double I miniplates with monocortical screws were compared under vertical, horizontal, and oblique load conditions by means of finite element analysis. A three-dimensional finite element model of a fully dentate mandible was generated. A 3 and 5 mm superior repositioning of mandibular anterior segmental osteotomy were simulated. Three different finite element models corresponding to different fixation configurations were created for each superior repositioning. The von Mises stress values on fixation appliances and principal maximum stresses (Pmax) on bony structures were predicted by finite element analysis. The results have demonstrated that double right L configuration provides better stability with less stress fields in comparison with other fixation configurations used in this study.

  2. 螺旋输送机螺旋体优化设计%Optimization Design of Screw in Screw Conveyor

    Institute of Scientific and Technical Information of China (English)

    王铁流; 郭晓梅; 陈仙明

    2012-01-01

    The process of finite element analysis and optimization design of screw for screw conveyor with the Pro/Engineer is discussed, the main steps and methods are also introduced. Subject to the requirements of the structural parameters and design objectives, the optimal design is realized efficiently and rapidly. A practical method is improved for the design quality of screw.%应用Pro/Engineer软件,研究了螺旋输送机螺旋体的有限元分析和优化设计方法和过程,介绍了设计过程的主要步骤和方法.在满足结构参数和设计目标要求的前提下,快捷、有效地实现了优化设计,提高了设计质量,为螺旋体的设计提供了一种有效的方法.

  3. Delayed Esophageal Pseudodiverticulum after Anterior Cervical Spine Fixation: Report of 2 Cases

    Directory of Open Access Journals (Sweden)

    Ali Sadrizadeh

    2015-03-01

    Full Text Available Introduction: Although perforation of the esophagus, in the anterior cervical spine fixation, is well established, cases with delayed onset, especially cases that present pseudodiverticulum, are not common. In addition, management of the perforation in this situation is debated.  Case Report:   Delayed esophageal pseudodiverticulum was managed in two patients with a history of anterior spine fixation. Patients were operated on, the loose plate and screws were extracted, the wall of the diverticulum was excised, the perforation on the nasogastric tube was suboptimally repaired, and a closed suction drain was placed there. The NGT was removed on the 7th day and barium swallow demonstrated no leakage at the operation site; therefore, oral feeding was started without any problem.  Conclusion:  In cases with delayed perforation, fistula, or diverticulum removal of anterior fixation instruments, gentle repair of the esophageal wall without persistence on definitive and optimal perforation closure, wide local drainage, early enteral nutrition via NGT, and antibiotic prescription is suggested.

  4. Design of Formed Milling Cutter for Double-Helix Screw Based on Noninstantaneous Envelope Method

    Directory of Open Access Journals (Sweden)

    Yun Li

    2013-01-01

    Full Text Available The design theory and method of formed milling cutter for double-helix screw of progressing cavity pump are presented. Through analyzing the shape and characteristic parameters of double-helix screw, the helicoids equation and axial curve equation of double-helix screw were established. According to the relative position relations between formed milling cutter and double-helix screw in the machining process, the geometric mapping relationship of screw coordinate system and formed milling cutter coordinate system was established by using the coordinate transformation theory. Based on noninstantaneous envelope method and the meshing conditions between formed milling cutter and double-helix screw, the contact line equations were established by minimum value method. By analyzing the machining errors caused by resharpening the formed milling cutter, the tooth back curve equation was established based on spiral of Archimedes, and the profile equation of formed milling cutter with constant back angle was got. On this basis, the formed milling cutter of processing double-helix screw was designed, and the cutter head and tool post were manufactured, respectively. The measuring results have shown that this method can satisfy the requirements of machining accuracy for double-helix screw. So this is an effective method to get formed milling cutter profile for double-helix screw.

  5. Innovative approach in the development of computer assisted algorithm for spine pedicle screw placement.

    Science.gov (United States)

    Solitro, Giovanni F; Amirouche, Farid

    2016-04-01

    Pedicle screws are typically used for fusion, percutaneous fixation, and means of gripping a spinal segment. The screws act as a rigid and stable anchor points to bridge and connect with a rod as part of a construct. The foundation of the fusion is directly related to the placement of these screws. Malposition of pedicle screws causes intraoperative complications such as pedicle fractures and dural lesions and is a contributing factor to fusion failure. Computer assisted spine surgery (CASS) and patient-specific drill templates were developed to reduce this failure rate, but the trajectory of the screws remains a decision driven by anatomical landmarks often not easily defined. Current data shows the need of a robust and reliable technique that prevents screw misplacement. Furthermore, there is a need to enhance screw insertion guides to overcome the distortion of anatomical landmarks, which is viewed as a limiting factor by current techniques. The objective of this study is to develop a method and mathematical lemmas that are fundamental to the development of computer algorithms for pedicle screw placement. Using the proposed methodology, we show how we can generate automated optimal safe screw insertion trajectories based on the identification of a set of intrinsic parameters. The results, obtained from the validation of the proposed method on two full thoracic segments, are similar to previous morphological studies. The simplicity of the method, being pedicle arch based, is applicable to vertebrae where landmarks are either not well defined, altered or distorted.

  6. VARIANTS OF SPINE OSTEOSYNTESIS AT LOW MINERAL DENSITY OF BONE

    Directory of Open Access Journals (Sweden)

    V. D. Usikov

    2010-01-01

    Full Text Available The analysis of the results of transpedicular screw fixation in the treatment of patients with osteoporotic vertebral compression fractures was done. In the first group (N=27 the polysegmental transpedicular screw fixation was applied. In the second group (N=20 we used short-level stabilization with additional augmentation of transpedicular screws by bone cement. The spinal stability, restoration of function, correction of spine's deformation and pain relief was same in both groups. But in the second group the results was achieved with less traumatization and time of rehabilitation of the patients.

  7. C2 laminar screw and C1-2 transarticular screw combined with C1 laminar hooks for atlantoaxial instability with unilateral vertebral artery injury.

    Science.gov (United States)

    Guo, Qunfeng; Liu, Jun; Ni, Bin; Lu, Xuhua; Zhou, Fengjin

    2011-09-01

    Transarticular screw fixation (TASF) is technically demanding, with high risk of vertebral artery (VA) injury. How to manage intraoperative VA injury and choose optimal alternative fixation becomes a concern of spinal surgeons. In this study, the management strategy for a patient with suspected intraoperative VA injury was analyzed. A 53-year-old woman developed type II odontoid fracture and brain stem injury due to a motor vehicle accident 3 months earlier. After conservative treatments, the brain stem injury improved, but with residual ocular motility defect in the right eye. The odontoid fracture did not achieve fusion with displacement and absorption of fracture fragments. After admission, atlantoaxial fixation using bilateral C1-2 transarticular screws (TASs) combined with C1 laminar hooks was planed. The first TAS was inserted successfully. Unfortunately, suspected VA injury developed during tapping the tract for the second TAS. Considering the previous brain stem injury and that directly inserting the screw to tamponade the hemorrhage might cause VA stenosis or occlusion, we blocked the screw trajectory with bone wax. C2 laminar screw was implanted instead of intended TAS on the injured side. The management strategy for suspected VA injury should depend on intraoperative circumstances and be tailored to patients. Blocking screw trajectory with bone wax is a useful method to stop bleeding. Atlantoaxial fixation using C2 laminar screw and C1-2 TAS combined with C1 laminar hooks is an ideal alternative procedure.

  8. Juvenile idiopathic scoliosis treated with posterior arthrodesis and segmental pedicle screw instrumentation before the age of 9 years: a 5-year follow-up

    Directory of Open Access Journals (Sweden)

    Musaoğlu Resul

    2009-01-01

    Risser 0 patients with open triradiate cartilages, routine combined anterior fusion to prevent crankshaft may not be warranted by posterior segmental pedicle screw instrumentation.

  9. Biomechanical impact of C2 pedicle screw length in an atlantoaxial fusion construct

    Directory of Open Access Journals (Sweden)

    Risheng Xu

    2014-01-01

    Full Text Available Background: Posterior, atlantoaxial (AA fusions of the cervical spine may include either standard (26 mm or short (16 mm C2 pedicle screws. This manuscript focused on an in vitro biomechanical comparison of standard versus short C2 pedicle screws to perform posterior C1-C2 AA fusions. Methods: Twelve human cadaveric spines underwent C1 lateral mass screw and standard C2 pedicle screw (n = 6 versus short C2 pedicle screw (n = 6 fixation. Six additional controls were not instrumented. The peak torque, peak rotational interval, and peak stiffness of the constructs were analyzed to failure levels. Results: The peak torque to construct failure was not statistically significantly different among the control spine (12.2 Nm, short pedicle fixation (15.5 Nm, or the standard pedicle fixation (11.6 Nm, P = 0.79. While the angle at the peak rotation statistically significantly differed between the control specimens (47.7° of relative motion and the overall instrumented specimens (P < 0.001, the 20.7° of relative rotation in the short C2 pedicle screw specimens was not statistically significantly higher than the 13.7° of relative rotation in the standard C2 pedicle screw specimens (P = 0.39. Similarly, although the average stiffness was statistically significantly lower in control group (0.026 Nm/degree versus the overall instrumented specimens (P = 0.001, the standard C2 pedicle screws (2.54 Nm/degree did not differ from the short C2 pedicle screws (1.69 Nm/degree (P = 0.30. Conclusions: Both standard and short C2 pedicle screws allow for equally rigid fixation of C1 lateral mass-C2 AA fusions. Usage of a short C2 pedicle screw may be an acceptable method of stabilization in carefully selected patient populations.

  10. Anterior chest wall examination reviewed

    Directory of Open Access Journals (Sweden)

    F. Trotta

    2011-09-01

    Full Text Available Anterior chest wall involvement is not infrequently observed within inflammatory arthropaties, particularly if one considers seronegative spondiloarthritides and SAPHO syndrome. Physical examination is unreliable and conventional X-rays analysis is an unsatisfactory tool during diagnostic work-up of this region. Scintigraphic techniques yield informations both on the activity and on the anatomical extent of the disease while computerized tomography visualize the elementary lesions, such as erosions, which characterize the process. Moreover, when available, magnetic resonance imaging couple the ability to finely visualize such lesions with the possibility to show early alterations and to characterize the “activity” of the disease, presenting itself as a powerful tool both for diagnosis and follow-up. This review briefly shows the applications of imaging techniques for the evaluation of the anterior chest wall focusing on what has been done in the SAPHO syndrome which can be considered prototypical for this regional involvement since it is the osteo-articular target mainly affected by the disease.

  11. Atlantoaxial screw fixation for the treatment of isolated and combined unstable jefferson fractures - experiences with 8 patients.

    Science.gov (United States)

    Hein, C; Richter, H-P; Rath, S A

    2002-11-01

    The unstable atlas burst fracture ("Jefferson fracture") is a fracture of the anterior and posterior atlantal arch with rupture of the transverse atlantal ligament and an incongruence of the atlanto-occipital and the atlanto-axial joint facets. The question whether it has to be treated surgically or nonsurgically is still discussed and remains controversial. During the last decade 8 patients with unstable atlas burst fractures were examined and treated in our department. Five of the eight patients were first treated conservatively by external immobilization. Because of continuing instability due to insufficient bony fusion of the atlantal fracture all five patients underwent atlanto-axial transarticular screw fixation and fusion - as described by Magerl - with good results. In all 8 patients a good bony fusion of the atlanto-axial segment was achieved. None of the patients exhibited neurological deficits after surgical treatment. Although immobilization with a halo vest is recommended by most authors, from our view primary transarticular C1-C2 screw fixation has to be discussed as an alternative for unstable atlas burst fractures. Nonsurgical treatment with halo extension always bears the risk of insufficient healing with further instability and a fixated incongruence of the atlanto-occipital and the atlanto-axial joints, leading to arthrosis, immobility and increasing neck pain. After 10 weeks of insufficient immobilization secondary pre- and intra-operative reposition manoeuvres and surgical fixation hardly can reverse this fixated incongruence. Moreover, halo-extension needs an immobilization of the cervical spine for about 10 weeks and more, which is very uncomfortable and leads to further complications especially in elderly patients.

  12. Application of Intraoperative CT-Guided Navigation in Simultaneous Minimally Invasive Anterior and Posterior Surgery for Infectious Spondylitis

    Science.gov (United States)

    Dubey, Navneet Kumar; Lee, Ching-Yu; Li, Yen-Yao; Cheng, Chin-Chang; Shi, Chung-Sheng

    2017-01-01

    This study was aimed at evaluating the safety and efficacy of using intraoperative computed tomography- (iCT-) guided navigation in simultaneous minimally invasive anterior and posterior surgery for infectious spondylitis. Nine patients with infectious spondylitis were enrolled in this study. The average operative time was 327.6 min (range, 210–490) and intraoperative blood loss was 407 cc (range, 50–1,200). The average duration of hospital stay was 48.9 days (range, 11–76). Out of a total of 54 pedicle screws employed, 53 screws (98.1%) were placed accurately. A reduced visual analog scale on back pain (from 8.2 to 2.2) and Oswestry disability index (from 67.1% to 25.6%) were found at the 2-year follow-up. All patients had achieved resolution of spinal infection with reduced average erythrocyte sedimentation rate (from 83.9 to 14.1 mm/hr) and average C-reactive protein (from 54.4 to 4.8 mg/dL). Average kyphotic angle correction was 10.5° (range, 8.4°–12.6°) postoperatively and 8.5° (range, 6.9°–10.1°) after 2 years. In conclusion, the current iCT-guided navigation approach has been demonstrated to be an alternative method during simultaneous minimally invasive anterior and posterior surgery for infectious spondylitis. It can provide a good intraoperative orientation and visualization of anatomic structures and also a high pedicle screw placement accuracy in patient's lateral decubitus position.

  13. A Technique for Removal of Forearm Dynamic Compression Plate with Stripped Screws: A Report of Three Cases

    Directory of Open Access Journals (Sweden)

    CK Lee

    2009-05-01

    Full Text Available Removal of plates is a procedure commonly performed by orthopaedic surgeons and stripped screws are probably the most common problem encountered during this procedure. Stripped screws are caused by slippage between the screwdriver and the screw. Due to the inherent difficulty in removing such screws, surgeons should be knowledgeable in techniques for their removal and should be equipped with the proper instruments to expedite the procedure. There are few published articles about such techniques. This report describes a technique for removal of plates with stripped screws. The tip of a stripped screw is approached from the far cortex and then reamed with a trephine reamer in the direction of the screw until both cortices are cleared. The plate is then removed with stripped screws attached. All the removals utilizing this technique to date have been successful with no complications, and this method is safe, efficient and technically easy to learn.

  14. Posterior Titanium Screw Fixation without Debridement of Infected Tissue for the Treatment of Thoracolumbar Spontaneous Pyogenic Spondylodiscitis

    Science.gov (United States)

    Iacoangeli, Maurizio; Nasi, Davide; Nocchi, Niccolo; Di Rienzo, Alessandro; di Somma, Lucia; Colasanti, Roberto; Vaira, Carmela; Benigni, Roberta; Liverotti, Valentina; Scerrati, Massimo

    2016-01-01

    Study Design Retrospective study. Purpose The aim of our study was to analyze the safety and effectiveness of posterior pedicle screw fixation for treatment of pyogenic spondylodiscitis (PSD) without formal debridement of the infected tissue. Overview of Literature Posterior titanium screw fixation without formal debridement of the infected tissue and anterior column reconstruction for the treatment of PSD is still controversial. Methods From March 2008 to June 2013, 18 patients with PSD underwent posterior titanium fixation with or without decompression, according to their neurological deficit. Postero-lateral fusion with allograft transplantation alone or bone graft with both the allogenic bone and the autologous bone was also performed. The outcome was assessed using the visual analogue scale (VAS) for pain and the Frankel grading system for neurological status. Normalization both of C-reactive protein (CRP) and erythrocyte sedimentation rate was adopted as criterion for discontinuation of antibiotic therapy and infection healing. Segmental instability and fusion were also analyzed. Results At the mean follow-up time of 30.16 months (range, 24–53 months), resolution of spinal infection was achieved in all patients. The mean CRP before surgery was 14.32±7.9 mg/dL, and at the final follow-up, the mean CRP decreased to 0.5±0.33 mg/dL (p <0.005). Follow-up computed tomography scan at 12 months after surgery revealed solid fusion in all patients. The VAS before surgery was 9.16±1.29 and at the final follow-up, it improved to 1.38±2.03, which was statistically significant (p <0.05). Eleven patients out of eighteen (61.11%) with initial neurological impairment had an average improvement of 1.27 grades at the final follow-up documented with the Frankel grading system. Conclusions Posterior screw fixation with titanium instrumentation was safe and effective in terms of stability and restoration of neurological impairment. Fixation also rapidly reduced back pain

  15. New Tools for Computational Geometry and Rejuvenation of Screw Theory

    Science.gov (United States)

    Hestenes, David

    Conformal Geometric Algebraic (CGA) provides ideal mathematical tools for construction, analysis, and integration of classical Euclidean, Inversive & Projective Geometries, with practical applications to computer science, engineering, and physics. This paper is a comprehensive introduction to a CGA tool kit. Synthetic statements in classical geometry translate directly to coordinate-free algebraic forms. Invariant and covariant methods are coordinated by conformal splits, which are readily related to the literature using methods of matrix algebra, biquaternions, and screw theory. Designs for a complete system of powerful tools for the mechanics of linked rigid bodies are presented.

  16. A description of the dynamics of manipulators using screw theory

    Science.gov (United States)

    Akselrod, B. V.

    1985-04-01

    The paper is concerned with the derivation of Lagrange equations of the second kind for a manipulator consisting of N links each of which is coupled with the preceding link (except for the first link, which is coupled with a fixed base) through a single-degree-of-freedom joint. The joints can be translational or rotational; each joint is treated as a rigid body, and the possibility of allowing for elasticity in the hinges and joints is demonstrated. The kinetic energy is determined using the theory of kinematic screws.

  17. Pedicle Screw-Based Posterior Dynamic Stabilization: Literature Review

    Directory of Open Access Journals (Sweden)

    Dilip K. Sengupta

    2012-01-01

    Full Text Available Posterior dynamic stabilization (PDS indicates motion preservation devices that are aimed for surgical treatment of activity related mechanical low back pain. A large number of such devices have been introduced during the last 2 decades, without biomechanical design rationale, or clinical evidence of efficacy to address back pain. Implant failure is the commonest complication, which has resulted in withdrawal of some of the PDS devices from the market. In this paper the authors presented the current understanding of clinical instability of lumbar motions segment, proposed a classification, and described the clinical experience of the pedicle screw-based posterior dynamic stabilization devices.

  18. RESEARCH OF A HIGH EFFICIENCY SLIDING SCREW DRIVER

    Institute of Scientific and Technical Information of China (English)

    Hu Xiaowei; Lu Huailiang; Huang Shuhuai

    2004-01-01

    A high efficiency sliding screw driver is introduced. It can improve driving efficiency obviously. As the material strength of the nut in this structure is low and the nut is the most dangerous part, so it is important to master the structure's characters of deformation and stress. The deformation and stress of this structure are researched by finite element method(FEM), and the changing law of stress concentration coefficient of the structure is gained. So the exact stress of nut teeth with highest load can be calculated directly based on this result.

  19. Positioning of anterior teeth in removable dentures

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    Strajnić Ljiljana

    2002-01-01

    Full Text Available Introduction The aim of this paper was to present methods of placement of artificial anterior teeth in edentulous individuals. The following review takes account of the majority of papers published during the last 100 years. The review has been divided into sections regarding the method used to determine the position of artificial anterior teeth. Geometric aspect Gysi (1895-1920 produced the first scientific theory about the position of artificial anterior teeth. Physiognomic theory The aim of this theory is to find the most natural position for artificial anterior teeth for each individual. Camper's "face angle" as a physiognomic criterion, has been introduced in papers of Wehrli (1961, Marxhors (1966, Tanzer (1968, Lombardi (1973. Esthetic aspect Important names in the field of dental esthetics are: Schön and Singer (1961, Arnheim (1965, Krajiček (1969, Tanzer (1968, Lombardi (1973, Goldstein (1976. They have introduced principles of visual aspects for selection of contours, dimension and position of artificial anterior teeth. Constitution aspect Flagg (1880, Williams (1913 and Hrauf (1957, 1958, have considered body constitution and individual characteristics regarding position of artificial anterior teeth. Physiological theory In 1971, Marxhors pointed to the fact that the position of artificial teeth corresponds with the function of the surrounding soft tissue and from the aspect of physiognomy as well. Phonetic aspect According to Silverman (1962 artificial anterior teeth are nearest when we pronounce the sound "S". Cephalometrical research Rayson (1970, Watson (1989, Strajnić Lj. (1999, Bassi F. (2001 have presented cephalometric radiographic analyses of natural anterior teeth compared with cephalometric radiographic analyses of artificial anterior teeth. A review of dental literature shows several factors suggesting modalities which should determine the position of artificial anterior teeth. Numerous methods have been designed for

  20. Incidental Anterior Cruciate Ligament Calcification: Case Report.

    Science.gov (United States)

    Hayashi, Hisami; Fischer, Hans

    2016-03-01

    The calcification of knee ligaments is a finding noted only in a handful of case reports. The finding of an anterior cruciate ligament calcification has been reported once in the literature. Comparable studies involving the posterior cruciate ligament, medial collateral ligament and an ossicle within the anterior cruciate ligament are likewise discussed in reports of symptomatic patients. We report a case of incidentally discovered anterior cruciate ligament calcification. We discuss the likely etiology and clinical implications of this finding.

  1. Reduction in radiation (fluoroscopy while maintaining safe placement of pedicle screws during lumbar spine fusion

    Directory of Open Access Journals (Sweden)

    Christopher D. Chaput

    2013-01-01

    Full Text Available OBJECTIVE: The purpose of this study is to report the results using PediGuard (electrical conductivity device to reduce radiation exposure while drilling the pilot hole for pedicle screw placement. METHOD: Eighteen patients diagnosed with a degenerative lumbar spine, that required a posterior spinal fusion. Average age of the patients were 55 ± 12 years. Patients received postoperative CT scans of all screws. Scans were reviewed by an independent reviewer grading 'in' 2 mm of breach. In a randomized fashion, the surgeon created pilot holes with either his standard technique or by using the PediGuard. Fluoroscopy was used for each drilling as necessary. Once the pilot hole was created, the surgeon inserted titanium screws into the pedicle pilot holes. A total of 78 screws (39 standard probe and 39 PediGuard were analyzed. RESULTS: 78 screws (39 standard probe and 39 PediGuard were analyzed. No significant difference in breach rate > 2mm by either method (p=1.000, with one screw out in each group. Fluoroscopy shots averaged 5.2 (range, 0 to 15, average decrease of 2.3 (30% per screw in the PediGuard group vs. 7.5 (range, 2 to 17 in the standard group (p< .001. CONCLUSION: This trial to assess pedicle probe location within the pedicle and vertebral body showed the number of fluoroscopy shots were reduced by 30%, compared to a standard probe while maintaining a 97.5% screw placement accuracy.

  2. Application of Richards Sliding Hip Screw in Treatment of Intertrochanteric Femoral Fractures

    Institute of Scientific and Technical Information of China (English)

    PING Jinzhong; SHEN Hongsheng; QIU Song

    2002-01-01

    @@ Richards Sliding Hip Screw is an effective method for the treatment of subtrochanteric and intertrochanteric femoral fractures. We applied the screw to treat the above- mentioned fractures from 1994 and obtained satisfying results in our hospital. All the cases were followed up. We reported it as follows.

  3. Is there enough evidence to regularly apply bone screws for intermaxillary fixation in mandibular fractures?

    NARCIS (Netherlands)

    A. Bins; M.A.E. Oomens; P. Boffano; T. Forouzanfar

    2015-01-01

    Purpose Intermaxillary fixation (IMF) is traditionally achieved with arch bars; however, this method has several well-known disadvantages and other techniques, such as bone screws, are available. This study evaluated current evidence regarding these IMF screws (IMFSs) for mandibular trauma and to as

  4. Pyrolysis of cassava rhizome in a counter-rotating twin screw reactor unit.

    Science.gov (United States)

    Sirijanusorn, Somsak; Sriprateep, Keartisak; Pattiya, Adisak

    2013-07-01

    A counter-rotating twin screw reactor unit was investigated for its behaviour in the pyrolysis of cassava rhizome biomass. Several parameters such as pyrolysis temperature in the range of 500-700°C, biomass particle size of twin screw reactor was relatively low, whereas the solids content was relatively high, compared to some other reactor configurations.

  5. A biomechanical study on fixation stability with twin hook or lag screw in artificial cancellous bone.

    Science.gov (United States)

    Olsson, O; Tanner, K E; Ceder, L; Ryd, L

    2002-01-01

    The twin hook has been developed as an alternative to the conventional lag screw to be combined with a barrelled side-plate in the treatment of trochanteric hip fractures. With two oppositely directed apical hooks introduced into the subchondral bone of the femoral head, the twin hook provides different stabilising properties to the lag screw. The femoral head purchase of the twin hook and the lag screw were compared in a biomechanical study using artificial cancellous bone, and responses to axial and torsional loading was determined. A distinct yield point in load and torque was noted for the lag screw, representing failure of the laminas supporting the threads. For the twin hook, gradual increase of load and torque occurred during impaction of the bone supporting the hooks. The peak loads and torques were higher for the lag screw, but were similar for both devices after 8 mm deformation. The stiffness was higher for the lag screw, but in counter-clockwise rotation the stiffness for the lag screw was negligible. The twin hook appeared to provide fixation stability comparable to that offered by the lag screw, but with conceivable advantages in terms of a deformation response involving bone impaction and gradually increasing stability.

  6. Complications of pedicle screws in lumbar and lumbosacral fusions in 105 consecutive primary operations

    NARCIS (Netherlands)

    Jutte, PC

    2002-01-01

    Pedicle screw fixation is technically demanding and associated with high complication rates. The aim of this study was to identify and quantify the pedicle screw-related complications in 105 consecutive operations. We retrospectively analysed 105 consecutive primary operations. We found complication

  7. 29 CFR 1926.305 - Jacks-lever and ratchet, screw, and hydraulic.

    Science.gov (United States)

    2010-07-01

    ... 29 Labor 8 2010-07-01 2010-07-01 false Jacks-lever and ratchet, screw, and hydraulic. 1926.305... Power § 1926.305 Jacks—lever and ratchet, screw, and hydraulic. (a) General requirements. (1) The... secured at once. (ii) Hydraulic jacks exposed to freezing temperatures shall be supplied with an...

  8. Robot assisted navigated drilling for percutaneous pedicle screw placement: A preliminary animal study

    Directory of Open Access Journals (Sweden)

    Hongwei Wang

    2015-01-01

    Conclusions: The preliminary study supports the view that computer assisted pedicle screw fixation using spinal robot is feasible and the robot can decrease the intraoperative fluoroscopy time during the minimally invasive pedicle screw fixation surgery. As spine robotic surgery is still in its infancy, further research in this field is worthwhile especially the accuracy of spine robot system should be improved.

  9. Comparison of two-transsacral-screw fixation versus triangular osteosynthesis for transforaminal sacral fractures.

    Science.gov (United States)

    Min, Kyong S; Zamorano, David P; Wahba, George M; Garcia, Ivan; Bhatia, Nitin; Lee, Thay Q

    2014-09-01

    Transforaminal pelvic fractures are high-energy injuries that are translationally and rotationally unstable. This study compared the biomechanical stability of triangular osteosynthesis vs 2-transsacral-screw fixation in the repair of a transforaminal pelvic fracture model. A transforaminal fracture model was created in 10 cadaveric lumbopelvic specimens. Five of the specimens were stabilized with triangular osteosynthesis, which consisted of unilateral L5-to-ilium lumbopelvic fixation and ipsilateral iliosacral screw fixation. The remaining 5 were stabilized with a 2-transsacral-screw fixation technique that consisted of 2 transsacral screws inserted across S1. All specimens were loaded cyclically and then loaded to failure. Translation and rotation were measured using the MicroScribe 3D digitizing system (Revware Inc, Raleigh, North Carolina). The 2-transsacral-screw group showed significantly greater stiffness than the triangular osteosynthesis group (2-transsacral-screw group, 248.7 N/mm [standard deviation, 73.9]; triangular osteosynthesis group, 125.0 N/mm [standard deviation, 66.9]; P=.02); however, ultimate load and rotational stiffness were not statistically significant. Compared with triangular osteosynthesis fixation, the use of 2 transsacral screws provides a comparable biomechanical stability profile in both translation and rotation. This newly revised 2-transsacral-screw construct offers the traumatologist an alternative method of repair for vertical shear fractures that provides biplanar stability. It also offers the advantage of percutaneous placement in either the prone or supine position.

  10. Screw-System-Based Mobility Analysis of a Family of Fully Translational Parallel Manipulators

    Directory of Open Access Journals (Sweden)

    Ernesto Rodriguez-Leal

    2013-01-01

    Full Text Available This paper investigates the mobility of a family of fully translational parallel manipulators based on screw system analysis by identifying the common constraint and redundant constraints, providing a case study of this approach. The paper presents the branch motion-screws for the 3-RP̲C-Y parallel manipulator, the 3-RCC-Y (or 3-RP̲RC-Y parallel manipulator, and a newly proposed 3-RP̲C-T parallel manipulator. Then the paper determines the sets of platform constraint-screws for each of these three manipulators. The constraints exerted on the platforms of the 3-RP̲C architectures and the 3-RCC-Y manipulators are analyzed using the screw system approach and have been identified as couples. A similarity has been identified with the axes of couples: they are perpendicular to the R joint axes, but in the former the axes are coplanar with the base and in the latter the axes are perpendicular to the limb. The remaining couples act about the axis that is normal to the base. The motion-screw system and constraint-screw system analysis leads to the insightful understanding of the mobility of the platform that is then obtained by determining the reciprocal screws to the platform constraint screw sets, resulting in three independent instantaneous translational degrees-of-freedom. To validate the mobility analysis of the three parallel manipulators, the paper includes motion simulations which use a commercially available kinematics software.

  11. Effect of Welding Methods on the Structure and Mechanical Properties of Welded Joints of Screw Piles

    Science.gov (United States)

    Golikov, N. I.; Sidorov, M. M.; Stepanova, K. V.

    2016-11-01

    Mechanical properties and characteristics of the structure of welded joints of screw piles are studied. It is shown that cast tips from steel 25L do not meet the performance specifications for operation in the Northern climatic zone. Quality welded joints of screw piles can be obtained by semiautomatic welding in an environment of CO2 with Sv-08G2S welding wire.

  12. Foreign body reaction after PLC reconstruction caused by a broken PLLA screw.

    Science.gov (United States)

    Kim, Tae-Kwon; Jeong, Tae-Wan; Lee, Dae-Hee

    2014-12-01

    Foreign body reactions may occur in patients who receive bioabsorbable implants during orthopedic surgery for fractures and ligament repair. The authors describe a 34-year-old man who presented with a palpable tender mass on the lateral aspect of the left knee of 1 month's duration. He underwent posterior cruciate ligament and posterolateral corner reconstruction 3 years earlier. Physical examination showed a 1×1-cm soft, nontender mass without localized warmth on the lateral epicondyle of the distal femur. Magnetic resonance imaging showed a broken screw fragment surrounded by a cyst-like mass. Under general anesthesia, the surgeon excised the screw fragment and the fibrotic mass, enclosing it in the subcutaneous tissue at the lateral epicondyle, the site at which a poly-L-lactic acid bioabsorbable screw had been inserted to fix the graft for posterolateral corner reconstruction. Histologic evaluation showed a foreign body reaction to the degraded screw particles. To the authors' knowledge, this report is the first description of a patient presenting with a delayed foreign body reaction to a broken poly-L-lactic acid bioabsorbable screw at the lateral femoral epicondyle after posterolateral corner reconstruction. Because delayed foreign body reactions can occur at any site of poly-L-lactic acid bioabsorbable screw insertion, care should be taken to avoid screw protrusion during ligament reconstruction because it can lead to screw breakage and delayed foreign body reaction.

  13. Determining the residence time distribution of various screw elements in a co-rotating twin-screw extruder by means of fluorescence spectroscopy

    Science.gov (United States)

    Lepschi, Alexander; Gerstorfer, Gregor; Miethlinger, Jürgen

    2015-05-01

    The Residence Time Distribution (RTD) is key to optimizing the mixing ability of an extruder. For both sensitive and reactive materials, it is important to know how long particles remain in the barrel and how long the polymer remains, for instance, in a kneading element. To assess the influence of different screw configurations on the RTD, a low-concentration tracer particle was injected into the feeding section and measured inline by fluorescence spectroscopy1 both inside the barrel and at the extruder exit. The measurements were conducted using polypropylene with different amounts of organic peroxide. Measuring the residence time at various positions along the screw allows the RTD to be determined for just one screw element. Furthermore, we show the influence of different screw configurations on the polydispersity of polypropylene.

  14. 髂骨钉三种置入通道的影像解剖学研究%Radiographic measurements of three iliac screws passage

    Institute of Scientific and Technical Information of China (English)

    陈辉; 刘明军; 王志强

    2011-01-01

    目的 通过对各髂骨钉通道的影像学测量,了解髂骨钉三种不同置入通道的参数并为其安全置入提供帮助.方法 选择40例髂骨外伤患者,男21例(16~75岁,27个髂骨翼),女19例(16~78岁,28个髂骨翼),均采用三维螺旋CT重建骨盆,并对髂结节到髂前下棘、髂后上棘到髂前下棘、髂后下棘到髂前下棘髂三种不同的髂骨钉通路进行测量,评价参数分别是长度、内径以及皮质厚度.结果 髂后上棘到髂前下棘通道有着最长的骨性通道,男性长为141 mm,女性长为129 mm,两髂骨板间可容纳在男性直径最大8 mm、女性6~7 mm的内植物,最佳髋关节上通道皮质骨厚度男性为5.2 mm、女性为4.7 mm术中髂骨钉的置入.结论 本研究提示为安全置入髂骨钉,男性长度140 mm直径8 mm、女性长度130 mm直径6 mm左右的髂骨钉是较为妥当的.%Objective To research the iliac screws placement and to supply reference data for iliac screw manufacturing,by radiographic measurements for secure placement of screws of Chinese adult ilium. Methods Measurements were made using three-dimensional computed tomographic reformations in 40 consecutive trauma patients(27 measurements in 21 males,16 to 75 years old;28 measurements in 19 females,16 to 78 years old).The parameters were the intrailiac length inner width,and cortical thickness of three different transiliac screw anchor paths aimed toward the anterior inferior iliac spine and initiated at the iliac tubercle,posterior superior iliac spine,or posterior inferior iliac spine. Results The posterior superior iliac spine-anterior inferior iliac spine path had the largest bony canal lengths, with 141 mm in male and 129 mm in female patients. Two stereotypic iliac constrictions allowed placement of 8 mm implants in male and 6-7 mm implants in female patients. Cortical thickness at that optimal extraarticular path was 5.2 mm in the male and 4.7 mm in the female patients. Conclusions Our

  15. To evaluate the use of modified power arm [Discopender 468] for efficient anterior teeth retraction - A clinical study

    Directory of Open Access Journals (Sweden)

    Hemavathi Patil

    2017-01-01

    Full Text Available Introduction: Many new bracket prescriptions and Techniques have been developed and modified as treatment mechanics progress to create force system that can work efficiently and shorten the orthodontic treatment period. Aim of this study was to evaluate the use of modified power arm [Discopender 468] for efficient anterior Teeth retraction, to determine anchorage loss and upper incisor changes after space closure. Material & Method: Ten patients of class II division1were selected to need maxillary first premolars was extracted and the retraction of anterior teeth was carried out segmentally by using discopender468 which applies variable force with respect to height of power arm. To prevent anchor loss during anterior retraction we have placed the mini implant screw mesial to 1stmolar bilaterally in maxillary arch. Pre and post lateral cephalograms were taken to determine the anchorage loss and upper incisor changes. Result and Conclusion: Anterior retraction carried out by a new design of discopender 468 and minim plant brings out controlled bodily tooth movement and also has variable force vectors, which is one of the variable method to use for retraction in Straight Wire Appliance in day to day orthodontic practices and also has advantage over conventional retraction mechanics.

  16. Micro-CT evaluation and histological analysis of screw-bone interface of expansive pedicle screw in osteoporotic sheep

    Institute of Scientific and Technical Information of China (English)

    WAN Shi-yong; LEI Wei; WU Zi-xiang; L(U) Rong; WANG Jun; FU Suo-chao; LI Bo; ZHAN Ce

    2008-01-01

    To investigate the properties of screwbone interface of expansive pedicle screw(EPS)in osteoporotic sheep by micro-CT and histological observation.Methods:Six female sheep with bilateral ovariectomyinduced osteoporosis were employed in this experiment.After EPS insertion in each femoral condvle, the sheep were randomly divided into two groups:3 sheep were bred for 3 months(Group A),while the other 3 were bred for 6 months(Group B). After the animals being killed,the femoral condyles with EPS were obtained,which were three-dimensionally-imaged and reconstructed by micro-CT. Histological evaluation was made thereafter.Results:The trabecular microstructure was denser at the screw-bone interface than in the distant parts in expansive section,especially within the spiral marking.In the nonexpansive section,however,there was no significant difference between the interface and the distant parts. The regions of interest(ROI)adjacent to EPS were reconstructed and analyzed by micro-CT with the same thresholds. The three-dimensional(3-D)parameters,including tissue mineral density(TMD),bone volume fraction(BVF,BV/TV),bone surface/bone volume(BS/BV) ratio, trabecular thickness(Tb. Th),and trabecular separation(Tb. Sp),were significantly better in expansive sections than non-expansive sections(P<0.05).Histologically,newly-formed bony trabeculae crawled along the expansive fissures and into the center of EPS. The newly-formed bones,as well as the bones at the bone-screw interface,closely contacted with the EPS and constructed four compartments.Conclusions:The findings of the current study,based on micro-CT and histological evaluation, suggest that EPS can significantly provide stabilization in osteoporotic cancellous bones.

  17. Use of the channel fill level in defining a design space for twin screw wet granulation.

    Science.gov (United States)

    Gorringe, L J; Kee, G S; Saleh, M F; Fa, N H; Elkes, R G

    2017-03-15

    Twin screw wet granulation is a key process in the continuous manufacture of oral solid dosage forms. Previous research has qualitatively suggested that the channel fill level influences the granules produced. In this paper a quantitative measure of the total volumetric fraction of the conveying element channels of the screw filled with powder (φ) was used. Experimental results are shown which demonstrate that very similar particle size distributions can be obtained at the same φ with the same material and screw configuration but radically different solids feed rates and screw speeds. Morphology of the granules also correlates with φ. This is consistent with previous observations in the literature correlating granule attributes with powder feed rate and screw speed but also considers the two parameters in combination. A process design space approach based on φ is proposed. This can be determined empirically, and potentially has value in setting process control strategies, assuring process robustness and allowing process flexibility during the product lifecycle.

  18. EFFECT OF THE SCREW TORQUE LEVEL ON THE INTERFRAGMENTARY STRAIN AND THE INTERFRAGMENTARY MODULUS

    Directory of Open Access Journals (Sweden)

    Boonthum Wongchai

    2013-01-01

    Full Text Available The screw torque is applied at the screw head to fix the plate and the bone. It generates the compressive force between the plate and the bone to stabilize them. The interfragmentary strain is the main factor for healing the bone fractured. The screw torque level affects the interfragmentary strain and the stability of the fixation between the plates an the bone. The interfragmentary modulus is the new factor of the plate fixation stability and it is affected by the torque level. This research is proposed to study the effect of the screw torque level on the interfragmentary strain and the interfragmentary modulus. The interfragmentary strain and the interfragmentary modulus decrease by increasing the screw torque level.

  19. Connection of Screw Instability with Electric Current in an Accretion Disc around a Black Hole

    Institute of Scientific and Technical Information of China (English)

    LAN Xiao-Xia; WANG Ding-Xiong; GAN Zhao-Ming

    2005-01-01

    @@ The screw instability of the magnetic field is discussed based on its poloidal configuration generated by a single toroidal electric current flowing in the equatorial plane of a Kerr Mack hole (BH). The rotation of the BH relative to the disc induces an electromotive force, which in turn results in a poloidal electric current. By using Ampere's law, we calculate the toroidal component of the magnetic field and derive a criterion for the screw instability of the magnetic field connecting the rotating BH with its surrounding disc. It is determined that the screw instability is related to two parameters: the radius of the disc and the BH spin. The occurrence of screw instability is depicted in a parameter space. In addition, we discuss the effect of the screw instability on magnetic extraction of energy from the rotating BH.

  20. Toxic Anterior Segment Syndrome (TASS

    Directory of Open Access Journals (Sweden)

    Özlem Öner

    2011-12-01

    Full Text Available Toxic anterior segment syndrome (TASS is a sterile intraocular inflammation caused by noninfectious substances, resulting in extensive toxic damage to the intraocular tissues. Possible etiologic factors of TASS include surgical trauma, bacterial endotoxin, intraocular solutions with inappropriate pH and osmolality, preservatives, denatured ophthalmic viscosurgical devices (OVD, inadequate sterilization, cleaning and rinsing of surgical devices, intraocular lenses, polishing and sterilizing compounds which are related to intraocular lenses. The characteristic signs and symptoms such as blurred vision, corneal edema, hypopyon and nonreactive pupil usually occur 24 hours after the cataract surgery. The differential diagnosis of TASS from infectious endophthalmitis is important. The main treatment for TASS formation is prevention. TASS is a cataract surgery complication that is more commonly seen nowadays. In this article, the possible underlying causes as well as treatment and prevention methods of TASS are summarized. (Turk J Oph thal mol 2011; 41: 407-13

  1. Evaluation of contributions of orthodontic mini-screw design factors based on FE analysis and the Taguchi method.

    Science.gov (United States)

    Lin, Chun-Li; Yu, Jian-Hong; Liu, Heng-Liang; Lin, Chih-Hao; Lin, Yang-Sung

    2010-08-10

    This study determines the relative effects of changes in bone/mini-screw osseointegration and mini-screw design factors (length, diameter, thread shape, thread depth, material, head diameter and head exposure length) on the biomechanical response of a single mini-screw insertion. Eighteen CAD and finite element (FE) models corresponding to a Taguchi L(18) array were constructed to perform numerical simulations to simulate mechanical responses of a mini-screw placed in a cylindrical bone. The Taguchi method was employed to determine the significance of each design factor in controlling strain. Simulation results indicated that mini-screw material, screw exposure length and screw diameter were the major factors affecting bone strain, with percentage contributions of 63%, 24% and 7%, respectively. Bone strain decreased obviously when screw material had the high elastic modulus of stainless/titanium alloys, a small exposure length and a large diameter. Other factors had no significant on bone strain. The FE analysis combined with the Taguchi method efficiently identified the relative contributions of several mini-screw design factors, indicating that using a strong stainless/titanium alloys as screw material is advantageous, and increase in mechanical stability can be achieved by reducing the screw exposure length. Simulation results also revealed that mini-screw and bone surface contact can provide sufficient mechanical retention to perform immediately load in clinical treatment.

  2. Fracture of the L-4 vertebral body after use of a stand-alone interbody fusion device in degenerative spondylolisthesis for anterior L3-4 fixation.

    Science.gov (United States)

    Kwon, Yoon-Kwang; Jang, Ju-Hee; Lee, Choon-Dae; Lee, Sang-Ho

    2014-06-01

    Many studies attest to the excellent results achieved using anterior lumbar interbody fusion (ALIF) for degenerative spondylolisthesis. The purpose of this report is to document a rare instance of L-4 vertebral body fracture following use of a stand-alone interbody fusion device for L3-4 ALIF. The patient, a 55-year-old man, had suffered intractable pain of the back, right buttock, and left leg for several weeks. Initial radiographs showed Grade I degenerative spondylolisthesis, with instability in the sagittal plane (upon 15° rotation) and stenosis of central and both lateral recesses at the L3-4 level. Anterior lumbar interbody fusion of the affected vertebrae was subsequently conducted using a stand-alone cage/plate system. Postoperatively, the severity of spondylolisthesis diminished, with resolution of symptoms. However, the patient returned 2 months later with both leg weakness and back pain. Plain radiographs and CT indicated device failure due to anterior fracture of the L-4 vertebral body, and the spondylolisthesis had recurred. At this point, bilateral facetectomies were performed, with reduction/fixation of L3-4 by pedicle screws. Again, degenerative spondylolisthesis improved postsurgically and symptoms eased, with eventual healing of the vertebral body fracture. This report documents a rare instance of L-4 vertebral body fracture following use of a stand-alone device for ALIF at L3-4, likely as a consequence of angular instability in degenerative spondylolisthesis. Under such conditions, additional pedicle screw fixation is advised.

  3. Posterior thoracic segmental pedicle screw instrumentation: Evolving methods of safe and effective placement

    Directory of Open Access Journals (Sweden)

    Zeiller S

    2005-01-01

    Full Text Available The use of pedicle screw instrumentation in the spine has evolved over the last two decades. The initial use of pedicle screws began in the lumbar spine. As surgeons have become more comfortable with the complex anatomy required for accurate screw placement, the use of pedicle instrumentation has evolved to include their use in the thoracolumbar and thoracic spine. The impetus behind their increased use is a result of the many advantages that pedicle screw anchorage offers over traditional hook and rod constructs. Improved deformity correction and overall construct rigidity are two important advantages of pedicle screw instrumentation due its three-column control over the spinal elements. First, pedicle screw instrumentation obviates the need to place instrumentation within the spinal canal with its inherent risk of neurologic injury. Second, the placement of pedicle screws is independent of facet or laminar integrity and thus has been extremely useful in traumatic, neoplastic, and degenerative conditions. The benefits of pedicle screws in the thoracic spine has been tempered by the potential for catastrophic neurological or soft tissue injuries due to the close proximity of these structures. The narrow and inconsistent shape of the thoracic pedicles, especially in spinal deformity, makes their placement technically challenging. As a result, surgeons have employed a number of techniques to ensure the safe and efficacious placement of thoracic pedicle screws. Detailed anatomic landmarks used to determine pedicle location, intraoperative imaging including navigation, and neurophysiological monitoring are some of the techniques currently used by surgeons. The implementation of these techniques and a thorough understanding of the complex three-dimensional anatomy have allowed surgeons to successfully place thoracic and thoracolumbar pedicle screws.

  4. Novel free-hand T1 pedicle screw method: Review of 44 consecutive cases

    Directory of Open Access Journals (Sweden)

    Mark A Rivkin

    2014-01-01

    Full Text Available Summary of Background Data: Multilevel posterior cervical instrumented fusions are becoming more prevalent in current practice. Biomechanical characteristics of the cervicothoracic junction may necessitate extending the construct to upper thoracic segments. However, fixation in upper thoracic spine can be technically demanding owing to transitional anatomy while suboptimal placement facilitates vascular and neurologic complications. Thoracic instrumentation methods include free-hand, fluoroscopic guidance, and CT-based image guidance. However, fluoroscopy of upper thoracic spine is challenging secondary to vertebral geometry and patient positioning, while image-guided systems present substantial financial commitment and are not readily available at most centers. Additionally, imaging modalities increase radiation exposure to the patient and surgeon while potentially lengthening surgical time. Materials and Methods: Retrospective review of 44 consecutive patients undergoing a cervicothoracic fusion by a single surgeon using the novel free-hand T1 pedicle screw technique between June 2009 and November 2012. A starting point medial and cephalad to classic entry as well as new trajectory were utilized. No imaging modalities were employed during screw insertion. Postoperative CT scans were obtained on day 1. Screw accuracy was independently evaluated according to the Heary classification. Results: In total, 87 pedicle screws placed were at T1. Grade 1 placement occurred in 72 (82.8% screws, Grade 2 in 4 (4.6% screws and Grade 3 in 9 (10.3% screws. All Grade 2 and 3 breaches were <2 mm except one Grade 3 screw breaching 2-4 mm laterally. Only two screws (2.3% were noted to be Grade 4, both breaching medially by less than 2 mm. No new neurological deficits or returns to operating room took place postoperatively. Conclusions: This modification of the traditional starting point and trajectory at T1 is safe and effective. It attenuates additional bone

  5. Study of Bone-screw Surface Fixation in Lumbar Dynamic Stabilization

    Directory of Open Access Journals (Sweden)

    Yun-Gang Luo

    2015-01-01

    Full Text Available Background: We aimed to use the animal model of dynamic fixation to examine the interaction of the pedicle screw surface with surrounding bone, and determine whether pedicle screws achieve good mechanical stability in the vertebrae. Methods: Twenty-four goats aged 2-3 years had Cosmic ® pedicle screws implanted into both sides of the L2-L5 pedicles. Twelve goats in the bilateral dynamic fixation group had fixation rods implanted in L2-L3 and L4-L5. Twelve goats in the unilateral dynamic fixation group had fixation rods randomly fixed on one side of the lumbar spine. The side that was not implanted with fixation rods was used as a static control group. Results: In the static control group, new bone was formed around the pedicle screw and on the screw surface. In the unilateral and bilateral dynamic fixation groups, large amounts of connective tissue formed between and around the screw threads, with no new bone formation on the screw surface; the pedicle screws were loose after the fixed rods were removed. The bone mineral density and morphological parameters of the region of interest (ROI in the unilateral and bilateral dynamic fixation group were not significantly different (P > 0.05, but were lower in the fixed groups than the static control group (P 0.05; however the maximum pull force of the fixation groups was significantly less than the static control group (P < 0.01. Conclusions: Fibrous connective tissue formed at the bone-screw interface under unilateral and bilateral pedicle dynamic fixation, and the pedicle screws lost mechanical stability in the vertebrae.

  6. Augmentation of screw fixation with injectable calcium sulfate bone cement in ovariectomized rats.

    Science.gov (United States)

    Yu, Xiao-Wei; Xie, Xin-Hui; Yu, Zhi-Feng; Tang, Ting-Ting

    2009-04-01

    The objective of this study was to determine the effect of augmenting screw fixation with an injectable calcium sulfate cement (CSC) in the osteoporotic bone of ovariectomized rats. The influence of the calcium sulfate (CS) on bone remodeling and screw anchorage in osteoporotic cancellous bone was systematically investigated using histomorphometric and biomechanical analyses. The femoral condyles of 55 Sprague-Dawley ovariectomized rats were implanted with screw augmented with CS, while the contralateral limb received a nonaugmented screw. At time intervals of 2, 4, 8, 12, and 16 weeks, 11 rats were euthanized. Six pair-matched samples were used for histological analysis, while five pair-matched samples were preserved for biomechanical testing. Histomorphometric data showed that CS augmented screws activated cancellous bone formation, evidenced by a statistically higher (p < 0.05) percentage of osteoid surface at 2, 4, and 8 weeks and a higher rate of bone mineral apposition at 12 weeks compared with nonaugmented screws. The amount of the bone-screw contact at 2, 8, and 12 weeks and of bone ingrowth on the threads at 4 and 8 weeks was greater in the CS group than in the nonaugmented group (p < 0.05), although these parameters increased concomitantly with time for both groups. The CS was resorbed completely at 8 weeks without stimulating fibrous encapsulation on the screw surface. Also, the cement significantly increased the screw pull-out force and the energy to failure at 2, 4, 8, and 12 weeks after implantation, when compared with the control group (p < 0.05). These results imply that augmentation of screw fixation with CS may have the potential to decrease the risk of implant failure in osteoporotic bone.

  7. Energy consumption analysis for a single screw extruder

    Energy Technology Data Exchange (ETDEWEB)

    Deng, Jing; Harkin-Jones, Eileen; Price, Mark; Karnachi, Nayeem [Queen' s Univ., Belfast (United Kingdom). School of Mechanical and Aerospace Engineering; Li, Kang [Queen' s Univ., Belfast (United Kingdom). School of Electronics, Electrical Engineering and Computer Science; Fei, Minrui [Shanghai Univ. (China). School of Mechatronic Engineering and Automation

    2013-07-01

    Polymer extrusion is regarded as an energy intensive production process, the real-time monitoring of both thermal energy and motor drive energy consumption becomes necessary for the development of energy efficient management system. The use of power meter is a simple and easy way to achieve this, however the cost sometimes can be high. Mathematical models based on the process settings provide an affordable alternative, but the resultant models cannot be easily extended to other extruders with different geometry. In this paper, simple and accurate energy real-time monitoring methods are developed for the analysis of energy consumption of the thermal heating and motor drive respectively. This is achieved by looking inside the controller, and use the control variables to calculate the power consumption. The developed methods are then adopted to study the effects of operating settings on the energy efficiency. These include the barrel heating temperature, water cooling temperature, and screw speed. The experimental results on Killion KTS-100 extruder show that the barrel heating temperature has a negative effect on energy efficiency, while the water cooling setting affects the energy efficiency positively but insignificantly. Undoubtedly, screw speed has the most significant effect on energy efficiency.

  8. Analysis of Third-Grade Fluid in Helical Screw Rheometer

    Directory of Open Access Journals (Sweden)

    M. Zeb

    2013-01-01

    Full Text Available The steady flow of an incompressible, third-grade fluid in helical screw rheometer (HSR is studied by “unwrapping or flattening” the channel, lands, and the outside rotating barrel. The geometry is approximated as a shallow infinite channel, by assuming that the width of the channel is large as compared to the depth. The developed second-order nonlinear coupled differential equations are reduced to single differential equation by using a transformation. Using Adomian decomposition method, analytical expressions are calculated for the the velocity profiles and volume flow rates. The results have been discussed with the help of graphs as well. We observed that the velocity profiles are strongly dependant on non-Newtonian parameter (β~, and with the increase in β~, the velocity profiles increase progressively, which conclude that extrusion process increases with the increase in β~. We also observed that the increase in pressure gradients in x- and z-direction increases the net flow inside the helical screw rheometer, which increases the extrusion process. We noticed that the flow increases as the flight angle increase.

  9. Prosopis pubescens (screw bean mesquite) seedlings are hyperaccumulators of copper.

    Science.gov (United States)

    Zappala, Marian N; Ellzey, Joanne T; Bader, Julia; Peralta-Videa, Jose R; Gardea-Torresdey, Jorge

    2013-08-01

    Due to health reasons, toxic metals must be removed from soils contaminated by mine tailings and smelter activities. The phytoremediation potential of Prosopis pubescens (screw bean mesquite) was examined by use of inductively-coupled plasma optical emission spectroscopy. Transmission electron microscopy was used to observe ultrastructural changes of parenchymal cells of leaves in the presence of copper. Elemental analysis was used to localize copper within leaves. A 600-ppm copper sulfate exposure to seedlings for 24 days resulted in 31,000 ppm copper in roots, 17,000 ppm in stems, 11,000 in cotyledons and 20 ppm in the true leaves. For a plant to be considered a hyperaccumulator, the plant must accumulate a leaf-to-root ratio <1. Screw bean mesquite exposed to copper had a leaf-to-root ratio of 0.355 when cotyledons were included. We showed that P. pubescens grown in soil is a hyperaccumulator of copper. We recommend that this plant should be field tested.

  10. Mild toxic anterior segment syndrome mimicking delayed onset toxic anterior segment syndrome after cataract surgery

    Directory of Open Access Journals (Sweden)

    Su-Na Lee

    2014-01-01

    Full Text Available Toxic anterior segment syndrome (TASS is an acute sterile postoperative anterior segment inflammation that may occur after anterior segment surgery. I report herein a case that developed mild TASS in one eye after bilateral uneventful cataract surgery, which was masked during early postoperative period under steroid eye drop and mimicking delayed onset TASS after switching to weaker steroid eye drop.

  11. Odontoid cannulated screw fixation using digital navigation based on three-dimensional printing technique%基于3D打印齿状突空心钉置入的数字化导航

    Institute of Scientific and Technical Information of China (English)

    陈宣煌; 张国栋; 吴长福; 林海滨; 陈旭; 余正希; 孙宇庆

    2015-01-01

    BACKGROUND:Odontoid fracture is very common in cervical spine injuries, the special position of odontoid process, which is adjacent to important anatomic structure, makes screw placement difficult, and a slight discrepancy in position and orientation of the inserted screw leads to a decrease in intensity of internal fixation, even invalid internal fixation. Therefore, it is very necessary to develop an individualized treatment protocol by which screws can be precisely and safely placed and which is worthy of clinical popularization. OBJECTIVE:To study the navigation of Mimics software and three dimensional (3D)-printed module in anterior odontoid cannulated screw fixation and to investigate its feasibility and accuracy. METHODS:Sixteen human cadaveric cervical spines were scanned by a continuous thin-slice CT scanner. Original DICOM CT images were three-dimensional y reconstructed using Mimics software. The screw channel and support column were designed for C2 vertebra odontoid cannulated screw fixation for odontoid fracture. Segmentation of bone surface was performed. Navigation modules with screw channel were built using 3D printing technique. Navigation modules were used to aid screw placement. Screw fitting and placement were evaluated using X-ray and CT scan. RESULTS AND CONCLUSION:Total y 16 navigation modules were built and 22 screws were implanted. During and after screw placement, the cortical bone along screw channel and surrounding the vertebral body was not cracked. Postoperative X-ray and CT scans showed that some factors regarding screw placement such as entry point, orientation and depth of placement were consistent with those ideal factors simulated by Mimics software. The navigation modules were closely attached to the corresponding bony structure in front of the vertebral body, with a satisfactory gomphosis. Screw fitting and stability were good during application. These results verify that with the aid of navigation module, anterior odontoid

  12. Full mouth rehabilitation of a patient with mandibular implant screw retained Fp-3 prosthesis opposing maxillary acrylic removable over-denture.

    Science.gov (United States)

    Jain, Ashish R; Nallaswamy, Deepak; Ariga, Padma; Philip, Jacob Mathew

    2013-04-01

    A hybrid denture is one that is fabricated over a metal framework and retained by screws threaded into the implant abutments. The anterior part of a mandibular hybrid denture is fixed on implants while the posterior part of the denture is extended and cantilevered from implants. This article presents the fabrication of a maxillary over-denture opposing mandibular implant retained hybrid prosthesis. A total of four implants were placed in the mandibular arch. Castable abutments were used to produce the optimal angulations. Framework was waxed, cast recovered, and the fit was refined until the framework seated passively on the master cast. The mandibular denture teeth were waxed to the hybrid framework, and a final wax try-in was performed to verify and correct maxillomandibular relations before processing. The prosthesis was inserted after verification of occlusion, retention, and stability. The rehabilitation of edentulous patients with hybrid dentures has been observed to achieve greater masticatory function and psychological satisfaction than with conventional over-dentures. Producing a passive-fitting substructure for a fixed removable screw retained hybrid prosthesis is arguably one of the most technically complex tasks in implant dentistry. The technique presented may not initially produce a perfectly passive framework, but use of disclosing media and adjusting the internal aspect of the casting can result in non-binding, fully seated prostheses.

  13. Full mouth rehabilitation of a patient with mandibular implant screw retained Fp-3 prosthesis opposing maxillary acrylic removable over-denture

    Directory of Open Access Journals (Sweden)

    Ashish R Jain

    2013-01-01

    Full Text Available A hybrid denture is one that is fabricated over a metal framework and retained by screws threaded into the implant abutments. The anterior part of a mandibular hybrid denture is fixed on implants while the posterior part of the denture is extended and cantilevered from implants. This article presents the fabrication of a maxillary over-denture opposing mandibular implant retained hybrid prosthesis. A total of four implants were placed in the mandibular arch. Castable abutments were used to produce the optimal angulations. Framework was waxed, cast recovered, and the fit was refined until the framework seated passively on the master cast. The mandibular denture teeth were waxed to the hybrid framework, and a final wax try-in was performed to verify and correct maxillomandibular relations before processing. The prosthesis was inserted after verification of occlusion, retention, and stability. The rehabilitation of edentulous patients with hybrid dentures has been observed to achieve greater masticatory function and psychological satisfaction than with conventional over-dentures. Producing a passive-fitting substructure for a fixed removable screw retained hybrid prosthesis is arguably one of the most technically complex tasks in implant dentistry. The technique presented may not initially produce a perfectly passive framework, but use of disclosing media and adjusting the internal aspect of the casting can result in non-binding, fully seated prostheses.

  14. Reconstruction of the anterior cruciate ligament of the knee

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    Nikolić Dragan

    2006-01-01

    Full Text Available Background/Aim. Numerous papers on reconstruction of the anterior cruciate ligament of the knee (ACL contribute to the significance of this method. The aim of this study was to analyze the outcome of the use of this surgical treatment method regardless the type of surgical intervention, graft, and the choice of the material for fixing. Methods. The study included 324 patients treated within the period from April 1997 to April 2004. Arthroscopically assisted ACL reconstruction was typically performed using the central one-third of the patellar ligament, as a graft, with bone blocks. Fixing was performed using screws (spongy or interferential, Mitek type. In the cases who required revision of the surgery, we used a graft m. semitendinosus and m. gracilise (STG or a graft of the patellar ligament (B-Pt-B. Fixation in these cases was performed using absorptive wedges according to the Rigidfix technique or metallic implants. Results. The analysis included the results of the reconstruction of the anterior cruciate ligament of the knee (B-Pt-B or STG graft in 139 of the knees. Chronic injuries were revealed in 132 (94.9% of the knees. According to the anamnesis and clinical findings, the feeling of instability prevailed in 132 (94.9% of the knees, pain in 72 (51.7%, effluents in 24 (17.2%, and blockages in 13 (9.3%. Early and late postoperative complications were noticeable in 3.5% each. Hypotrophy of the upper knee musculature up to 2 cm was present in 53.9% of the operated knees, while minor contractions in 13.6% of them. The final result of the reconstruction graded begusing the Lysholm Scale was 85.2, simultaneous reconstructions of other ligaments 75.3, and revision surgery 68.0. First-grade degenerative postoperative changes according to the K/L Scale were found in 55.0% of the surgically treated knees, while the worst, four-grade one in 2.5%. Conclusion. On the basis of these findings, we can conclude that this method is the method of choice in

  15. Anterior urethral diverticulum: A rare presentation

    Directory of Open Access Journals (Sweden)

    Annavarupu Gopalkrishna

    2016-01-01

    Full Text Available Congenital anomalies of the urogenital tract are the most common anomalies found in the foetus, neonates and infants, but anterior urethral valves and diverticula are rare. Here, we present a case with congenital anterior urethral diverticulum associated with patent ductus arteriosus and polydactyly.

  16. Totally thrombosed giant anterior communicating artery aneurysm

    Directory of Open Access Journals (Sweden)

    V R Roopesh Kumar

    2015-01-01

    Full Text Available Giant anterior communicating artery aneurysmsarerare. Apatient presented with visual dysfunction, gait ataxia and urinary incontinence. MRI showed a giant suprasellar mass.At surgery, the lesion was identified as being an aneurysm arising from the anterior communicating artery.The difficulty in preoperative diagnosis and relevant literature are reviewed.

  17. Anterior segment complications of retinal photocoagulation.

    Science.gov (United States)

    Kanski, J J

    1975-03-01

    Seven patients had anterior segment complications following xenon arc retinal photocoagulation. Irreversible keratopathy was induced in two cases; all patients showed evidence of iris injury. The absorption of radiation by the iris was considered the main factor in producing overheating of the anterior segment.

  18. Anterior cervical hypertrichosis: a sporadic case.

    Science.gov (United States)

    Bostan, Sezen; Yaşar, Şirin; Serdar, Zehra Aşiran; Gizlenti, Sevda

    2016-03-01

    Anterior cervical hypertrichosis is a very rare form of primary localized hypertrichosis. It consists of a tuft of terminal hair on the anterior neck just above the laryngeal prominence. The etiology is still unknown. In this article, we reported a 15-year-old female patient who presented to our clinic with a complaint of hypertrichosis on the anterior aspect of the neck for the last five years. Her past medical history revealed no pathology except for vesicoureteral reflux. On the basis of clinical presentation, our patient was diagnosed with anterior cervical hypertrichosis and she was considered to be a sporadic case due to lack of other similar cases in familial history. To date, 33 patients with anterior cervical hypertrichosis have been reported. Anterior cervical hypertrichosis can be associated with other abnormalities, but it frequently presents as an isolated defect (70%). The association of vesicoureteral reflux and anterior cervical hypertrichosis which was observed in our patient might be coincidental. So far, no case of anterior cervical hypertrichosis associated with vesicoureteral reflux has been reported in the literature.

  19. 骶髂螺钉内固定力学性能的三维有限元分析%Analysising the Mechanical Properties of the Sactciliac Screw by Three-dimensional Finite Element

    Institute of Scientific and Technical Information of China (English)

    黄继锋; 刘新园; 张美超; 向杰; 胡辉

    2011-01-01

    Objective To evaluate biomechanical properties of the sactciliac screw by three-dimensional finite element for providing theory basis to choice the internal fixation ways of the sacroiliac joint fracture dislocation. Methods Establishing finite element models of simple sacroiliac joint dislocation (A model), and the sacroiliac joint dislocation and pubic symphysis separation (B model). They were fixed using both single Si screws (I class fixed) and Si, S2 double screws (II class fixed). Four models (A I , A II , B I and BII) were loaded arid analysised nonlinearly by the finite element. Results ①Comparative results of the maximal displacement: A II A I > BII > A II >normal pelvic.②Stress convective of the Si screw: the stress of the S, screw concentrately distributes, and the peak appears in the places passing the sacroiliac joints. Conclusion ?After anatomical reattachment of the pure fracture dislocation of sacroiliac joints, pelvic ring fixed by S1 screw the can obtain reliablestability. Thus, no significance to take a risk to insert the S2 screw. ?When the sacroiliac joint fracture dislocate and the pubic symphysis separate, the posterior ring fixed purely by S1 screw can't restore the stability. The best fixation is the anterior ring fixed by steel plates and the posterior ring fixed by the S1 screw. ③The S1 screw easily produces fixed fatigue and breakages in the places passing the sacroiliac joints.%目的 利用三维有限元评价骶髂螺钉内固定的力学性能,为骶髂关节骨折脱位固定方式的选择提供理论依据.方法 建立单纯骶髂关节脱位(A模型)与骶髂关节脱位+耻骨联合分离(B模型)有限元模型.两模型分别应用S1单螺钉(Ⅰ类固定)与S1、S2双螺钉固定(Ⅱ类固定).对AⅠ、AⅡ、BⅠ与BⅡ进行加载与非线性有限元分析.结果(①最大位移比较结果:AⅡ<BⅡ<A Ⅰ<正常骨盆<B Ⅰ;最大应力比较结果:B Ⅰ >A Ⅰ >BⅡ>AⅡ>正常

  20. Individualized 3D printing navigation template for pedicle screw fixation in upper cervical spine

    Science.gov (United States)

    Guo, Fei; Dai, Jianhao; Zhang, Junxiang; Ma, Yichuan; Zhu, Guanghui; Shen, Junjie; Niu, Guoqi

    2017-01-01

    Purpose Pedicle screw fixation in the upper cervical spine is a difficult and high-risk procedure. The screw is difficult to place rapidly and accurately, and can lead to serious injury of spinal cord or vertebral artery. The aim of this study was to design an individualized 3D printing navigation template for pedicle screw fixation in the upper cervical spine. Methods Using CT thin slices data, we employed computer software to design the navigation template for pedicle screw fixation in the upper cervical spine (atlas and axis). The upper cervical spine models and navigation templates were produced by 3D printer with equal proportion, two sets for each case. In one set (Test group), pedicle screws fixation were guided by the navigation template; in the second set (Control group), the screws were fixed under fluoroscopy. According to the degree of pedicle cortex perforation and whether the screw needed to be refitted, the fixation effects were divided into 3 types: Type I, screw is fully located within the vertebral pedicle; Type II, degree of pedicle cortex perforation is 1 mm or with the poor internal fixation stability and in need of renovation. Type I and Type II were acceptable placements; Type III placements were unacceptable. Results A total of 19 upper cervical spine and 19 navigation templates were printed, and 37 pedicle screws were fixed in each group. Type I screw-placements in the test group totaled 32; Type II totaled 3; and Type III totaled 2; with an acceptable rate of 94.60%. Type I screw placements in the control group totaled 23; Type II totaled 3; and Type III totaled 11, with an acceptable rate of 70.27%. The acceptability rate in test group was higher than the rate in control group. The operation time and fluoroscopic frequency for each screw were decreased, compared with control group. Conclusion The individualized 3D printing navigation template for pedicle screw fixation is easy and safe, with a high success rate in the upper cervical spine

  1. 成人腰椎侧凸椎弓根螺钉误置模式%Misplacement patterns of pedicle screws in surgical correction for adult lumbar scoliosis

    Institute of Scientific and Technical Information of China (English)

    丁旗; 邱勇; 孙旭; 朱峰; 王斌; 朱泽章; 吴涛; 徐磊磊

    2011-01-01

    Objective To identify the patterns and risk factors of pedicle screw misplacement in adults with lumbar scoliosis. Methods Form August 2010 to June 2011, 49 patients with lumbar scoliosis were treated by posterior fusion with using pedicle screws. There were 14 males and 35 females with an average age of 39. 2 ± 13. 8 years. Pedicle screws were inserted by freehand technique according to the anatomic landmarks. Postoperative CT scans were conducted. Pedicle perforations were assessed after measurement, and were classified as medial, lateral or anterior. Screw malpositionwas categorized into four grades: Grade 1, ≤5 2 mm; Grade 2, 2. 1-4. Omm; Grade 3, 4. 1-6. 0 mm; and Grade 4, ≥6. 1mm. Screw perforation >2mm of either pedicular or vertebral cortex were considered at potential risk, and with > 4mm of medial pedicular cortex perforation or contour of aorta was considered at high risk. The perforation rates of different groups were compared to analyze the risk factors. Results A total of 353 screws were inserted, and the average was 7. 2 per patient 316 screws (89. 5% ) were fully contained within the cortical boundaries of the pedicle. The remaining 37 (10.5% ) screws breached pedicle walls, and there were 25 screws with Grade 1, 8 with Grade 2, 1 with Grade 3 and 3 with Grade 4 perforation. Among the penetrations of the 12 screws at potential risk, 6 were lateral, 3 were medial, and 3 were anterior. No malpostioned screws were found at high risk. The screw perforation rate was similar between patients with age >50 years and patients with ages≤50 years (9. 9% versus 10.9% , P=0. 860). More perforations were found at the apical vertebra than the other levels of lumbar spine. Moreover, there was significant difference with regard to the perforation rate between the concave side (15.6% , 26/167) and the convex side (5.9% , 11/186) of the lumbar spine (P = 0.005). Significant difference ( P 60° (20.2%, 22/109) and patients with Cobb angled60° (6.1%, 15/244). In

  2. When Planning Screw Fracture Fixation Why the 5.5 mm Screw is the Goldilocks Screw. An Observational Computer Tomographic Study of Fifth Metatarsal Bone Anatomy in a Sample of Patients.

    Science.gov (United States)

    Iselin, Lukas D; Ramawat, Sunil; Hanratty, Brian; Klammer, Georg; Stavrou, Peter

    2015-05-01

    We wanted to verify our clinical experience that the 5.5 mm screw was ideal in the majority of fifth metatarsal fracture fixation. The size of a screw is important for the successful surgical treatment of these fractures in order to obtain the maximal stability while reducing the risk for iatrogenic fracture.A sample of patients undergoing computer tomographic imaging of the foot for investigation other than fifth metatarsal pathology were recruited. The parameters of the fifth metatarsal bone anatomy were measured.These parameters of the 5.5 mm screw were correlated with this data. The upper parameter (the diameter of the threads) was 5.5 and the lower parameter (the diameter of the shank) was 4.0 mm.Twenty seven patients were recruited.The proximal third internal diameter ranged from 3.6 to 7.0 mm with a mean of 5.0 mm. 93% of the metatarsals could easily accommodate the 5.5 mm screw. Two of the metatarsals had an internal diameter of < 4 mm (7%).It is our belief that the 5.5 mm screw may be used safely in the majority of patients with fifth metatarsal fractures.

  3. Use of self-tapping metal screws for temporary fixation of a resorbable plate system in maxillofacial surgery.

    Science.gov (United States)

    Iwai, Toshinori; Omura, Susumu; Aoki, Noriaki; Tohnai, Iwai

    2015-05-01

    Resorbable plate systems have been used in maxillofacial surgery to obviate the need for plate removal. However, resorbable plates and screws are very costly, and refixation with additional screws may be necessary when reduction or repositioning of the bone segment is inaccurate. Here we report the use of self-tapping metal screws for temporary fixation of a resorbable plating system in maxillofacial surgery to avoid the use of additional screws following inaccurate fixation or the reuse of resorbable screws, which may result in loosening.

  4. The biomechanical effect of artificial and human bone density on stopping and stripping torque during screw insertion.

    Science.gov (United States)

    Tsuji, Matthew; Crookshank, Meghan; Olsen, Michael; Schemitsch, Emil H; Zdero, Rad

    2013-06-01

    Orthopedic surgeons apply torque to metal screws manually by "subjective feel" to obtain adequate fracture fixation, i.e. stopping torque, and attempt to avoid accidental over-tightening that leads to screw-bone interface failure, i.e. stripping torque. Few studies have quantified stripping torque in human bone, and only one older study from 1980 reported stopping/ stripping torque ratio. The present aim was to measure stopping and stripping torque of cortical and cancellous screws in artificial and human bone over a wide range of densities. Sawbone blocks were obtained having densities from 0.08 to 0.80g/cm(3). Sixteen fresh-frozen human femurs of known standardized bone mineral density (sBMD) were also used. Using a torque screwdriver, 3.5-mm diameter cortical screws and 6.5-mm diameter cancellous screws were inserted for adequate tightening as determined subjectively by an orthopedic surgeon, i.e. stopping torque, and then further tightened until failure of the screw-bone interface, i.e. stripping torque. There were weak (R=0.25) to strong (R=0.99) linear correlations of absolute and normalized torque vs. density or sBMD. Maximum stopping torques normalized by screw thread area engaged by the host material were 15.2N/mm (cortical screws) and 13.4N/mm (cancellous screws) in sawbone blocks and 20.9N/mm (cortical screws) and 6.1N/mm (cancellous screws) in human femurs. Maximum stripping torques normalized by screw thread area engaged by the host material were 23.4N/mm (cortical screws) and 16.8N/mm (cancellous screws) in sawbone blocks and 29.3N/mm (cortical screws) and 8.3N/mm (cancellous screws) in human femurs. Combined average stopping/ stripping torque ratios were 80.8% (cortical screws) and 76.8% (cancellous screws) in sawbone blocks, as well as 66.6% (cortical screws) and 84.5% (cancellous screws) in human femurs. Surgeons should be aware of stripping torque limits for human femurs and monitor stopping torque during surgery. This is the first study of the

  5. One stage anterior-posterior approach for traumatic atlantoaxial instability combined with subaxial cervical spinal cord injury

    Institute of Scientific and Technical Information of China (English)

    WANG Chang-sheng; LIU Mou-jun; LIN Jian-hua; XU Wei-hong; LUO Hong-bin

    2011-01-01

    Objectives: To explore the clinical features of traumatic atlantoaxial instability combined with subaxial cervical spinal cord injury (CSCI), and to analyze the feasibility, indication and therapeutic effects of anterior-posterior approach in such cases.Methods: From March 2004 to September 2009, 16cases with this trauma were admitted and surgically treated in our department. Before surgery, skull traction was performed. Posterior atlantoaxial pedicle screw internal fixation and bone graft fusion were conducted to manage traumatic atlantoaxial instability. As for subaxial CSCI, anterior cervical corpectomy or discectomy decompression, bone grafting and internal fixation with steel plates were applied.Results: All operations were successful. The average operation time was 3 hours and operative blood loss 400 ml. Satisfactory reduction of both the upper and lower cervical spine and complete decompression were achieved. All patients were followed up for 12 to 36 months. Their clinical symptoms were improved by various levels. The Japanese Orthopaedic Association (JOA) scores ranged from 10to 16 one year postoperatively, 13.95±2.06 on average (improvement rate= 70.10% ). X-rays, spiral CT and MRI confirmed normal cervical alignments, complete decompression and fine implants' position. There was no breakage or loosening of screws, nor exodus of titanium mesh or implanted bone blocks. The grafted bone achieved fusion 3-6 months postoperatively and no atlantoaxial instability was observed.Conclusions: Traumatic atlantoaxial instability may combine with subaxial CSCI, misdiagnosis of which should be especially alerted and avoided. For severe cases, one stage anterior-posterior approach to decompress the upper and lower cervical spine, together with reposition, bone grafting and fusion, as well as internal fixation can immediately restore the normal alignments and stability of the cervical spine and effectively improve the spinal nervous function, thus being an ideal

  6. Spinal pedicle screw planning using deformable atlas registration

    Science.gov (United States)

    Goerres, J.; Uneri, A.; De Silva, T.; Ketcha, M.; Reaungamornrat, S.; Jacobson, M.; Vogt, S.; Kleinszig, G.; Osgood, G.; Wolinsky, J.-P.; Siewerdsen, J. H.

    2017-04-01

    Spinal screw placement is a challenging task due to small bone corridors and high risk of neurological or vascular complications, benefiting from precision guidance/navigation and quality assurance (QA). Implicit to both guidance and QA is the definition of a surgical plan—i.e. the desired trajectories and device selection for target vertebrae—conventionally requiring time-consuming manual annotations by a skilled surgeon. We propose automation of such planning by deriving the pedicle trajectory and device selection from a patient’s preoperative CT or MRI. An atlas of vertebrae surfaces was created to provide the underlying basis for automatic planning—in this work, comprising 40 exemplary vertebrae at three levels of the spine (T7, T8, and L3). The atlas was enriched with ideal trajectory annotations for 60 pedicles in total. To define trajectories for a given patient, sparse deformation fields from the atlas surfaces to the input (CT or MR image) are applied on the annotated trajectories. Mean value coordinates are used to interpolate dense deformation fields. The pose of a straight trajectory is optimized by image-based registration to an accumulated volume of the deformed annotations. For evaluation, input deformation fields were created using coherent point drift (CPD) to perform a leave-one-out analysis over the atlas surfaces. CPD registration demonstrated surface error of 0.89  ±  0.10 mm (median  ±  interquartile range) for T7/T8 and 1.29  ±  0.15 mm for L3. At the pedicle center, registered trajectories deviated from the expert reference by 0.56  ±  0.63 mm (T7/T8) and 1.12  ±  0.67 mm (L3). The predicted maximum screw diameter differed by 0.45  ±  0.62 mm (T7/T8), and 1.26  ±  1.19 mm (L3). The automated planning method avoided screw collisions in all cases and demonstrated close agreement overall with expert reference plans, offering a potentially valuable tool in support

  7. Occipital condyle screw placement and occipitocervical instrumentation using three-dimensional image-guided navigation.

    Science.gov (United States)

    Le, Tien V; Burkett, Clint; Ramos, Edwin; Uribe, Juan S

    2012-05-01

    Occipital condyle (OC) screws are an alternative cephalad fixation point in occipitocervical fusion. Safe placement of occipital, C1 lateral mass, and C2 pars screws have been described previously, but not OC screws. The craniocervical junction is complex, and a thorough understanding of the anatomy is needed. Three-dimensional (3D) image-guided navigation was used in six patients. There were no complications related to image-guided navigation during the placement of 12 OC screws and we found that this navigation can serve as a useful adjunct when placing an OC screw. Technical considerations of placing OC and C1 lateral mass screws are discussed with particular reference to patient positioning and the StealthStation® S7™ image-guided navigational platform (Medtronic, Minneapolis, MN, USA). The reference arc is attached to the head-clamp and faces forward. The optical camera and monitor are positioned at the head of the table for a direct, non-obstructed line-of-sight. To minimize intersegmental movement, the OC should not be drilled until all other screws have been placed. We conclude that 3D image-guided navigation is a useful adjunct that can be safely and effectively used for placement of instrumentation of the upper cervical spine including the OC.

  8. Investigation of a Ball Screw Feed Drive System Based on Dynamic Modeling for Motion Control

    Directory of Open Access Journals (Sweden)

    Yi-Cheng Huang

    2017-06-01

    Full Text Available This paper examines the frequency response relationship between the ball screw nut preload, ball screw torsional stiffness variations and table mass effect for a single-axis feed drive system. Identification for the frequency response of an industrial ball screw drive system is very important for the precision motion when the vibration modes of the system are critical for controller design. In this study, there is translation and rotation modes of a ball screw feed drive system when positioning table is actuated by a servo motor. A lumped dynamic model to study the ball nut preload variation and torsional stiffness of the ball screw drive system is derived first. The mathematical modeling and numerical simulation provide the information of peak frequency response as the different levels of ball nut preload, ball screw torsional stiffness and table mass. The trend of increasing preload will indicate the abrupt peak change in frequency response spectrum analysis in some mode shapes. This study provides an approach to investigate the dynamic frequency response of a ball screw drive system, which provides significant information for better control performance when precise motion control is concerned.

  9. Experimental investigation of granule size and shape dynamics in twin-screw granulation.

    Science.gov (United States)

    Kumar, Ashish; Vercruysse, Jurgen; Bellandi, Giacomo; Gernaey, Krist V; Vervaet, Chris; Remon, Jean Paul; De Beer, Thomas; Nopens, Ingmar

    2014-11-20

    A twin-screw granulator (TSG), a promising equipment for continuous high shear wet granulation (HSWG), achieves the desired level of mixing by a combination of the appropriate screw configuration and a suitable set of process settings (e.g. feed rate, screw speed, etc.), thus producing a certain granule size and shape distribution (GSSD). However, the primary sizing and shaping mechanism behind the resulting distribution is not well understood due to the opacity of the multiphase system in the granulator. This study experimentally characterised the GSSD dynamics along the TSG barrel length in order to understand the function of individual screw modules and process settings, as well as their interaction. Particle size analysis of granules collected at the outlet of the TSG suggested significant interaction between the process and screw configuration parameters influencing the heterogeneity in the GSSD. By characterising the samples collected along the screw length, a variable influence of the screw modules at different process conditions was observed. At low liquid-to-solid ratio (L/S), the first kneading module seemed to play a significant role in mixing, whereas the second kneading module was found to be more involved in reshaping the granules. At high L/S and high throughput, aggregation mainly took place in the second kneading module changing the GSSD. The results obtained from this study will be further used for the calibration and validation of a mechanistic model and, hence, support future development of a more detailed understanding of the HSWG process in a TSG.

  10. Management of Cannulated Screw Failure and Recurrent SCFE Displacement – Case Report

    Directory of Open Access Journals (Sweden)

    Nathan A Jacobson

    2014-01-01

    Full Text Available Introduction: SCFE occurs in 10 per 100,000 in some regions of the United States with the incidence continuing to increase. Percutaneous screw fixation is a well-accepted treatment for this disorder for over 20 years but management of complications is not well elucidated in the literature. Case Report: We describe a case where a traumatic unstable SCFE that was initially treated with closed reduction and fixation with a single transphyseal screw went on to hardware failure with recurrence of the deformity. The complication was successfully treated with closed reduction and re- cannulating the fractured screw within the epiphysis and extracting it using a conical extraction screw commonly referred to as an “easy out.” Three trans physeal screws were then placed for improved fixation strength. Follow-up at 9 months demonstrates a fused physis and no signs of avascular necrosis of the femoral head. Conclusion: Percutaneous management of SCFE screw breakage is possible utilizing specialized instruments and a precise and gentle manipulation preventing the need for more invasive treatments with their obligatory potential complications profile. Keywords: Hardware Failure, Slip Recurrence, SCFE, Complication, Conical Extraction Screw, Easy Out.

  11. The effect of screw insertion torque on tendons fixed with spiked washers.

    Science.gov (United States)

    Beynnon, B D; Meriam, C M; Ryder, S H; Fleming, B C; Johnson, R J

    1998-01-01

    The long-term success of a hamstring tendon graft depends not only on the type of device that is used for fixation but also on the mechanical interlocking of the soft tissue between the fixation device and bone. The purpose of this study was to evaluate the effect of screw insertion torque on the structural properties of soft tissue fixed to bone with a spiked metal washer. Two bovine tendons, one similar in size to a human semitendinosus tendon and the other similar in size to a human gracilis tendon, were secured to a bovine femur using a figure-of-8 technique with screws and metal spiked washers. A single load to failure was applied at 25 mm/sec. A significant positive linear correlation was observed between fixation screw insertion torque magnitude and the ultimate failure load value. An increase in the fixation screw insertion torque produced an increase in the ultimate failure load value. Similarly, there was a significant positive linear correlation between fixation screw insertion torque magnitude and the average maximum linear load value. No relationship was detected between screw insertion torque magnitude and the linear stiffness values of the tendon-fixation construct, indicating that a reproducible model was used. This study demonstrates that screw insertion torque is an important variable that controls the initial strength of soft tissue fixation to bone.

  12. Mechanical Comparison of Headless Screw Fixation and Locking Plate Fixation for Talar Neck Fractures.

    Science.gov (United States)

    Karakasli, Ahmet; Hapa, Onur; Erduran, Mehmet; Dincer, Cemal; Cecen, Berivan; Havitcioglu, Hasan

    2015-01-01

    For talar neck fractures, open reduction and internal fixation have been thought to facilitate revascularization and prevent osteonecrosis. Newer screw systems allow for placement of cannulated headless screws, which provide compression by virtue of a variable pitch thread. The present study compared the biomechanical fixation strength of cannulated headless variable-pitch screw fixation and locking plate fixation. A reproducible talar neck fracture was created in 14 fresh cadaver talar necks. Talar head fixation was then performed using 2 cannulated headless variable-pitch 4-mm/5-mm diameter (4/5) screws (Acutrak; Acumed, Hillsboro, OR) and locking plate fixation. Headless variable-pitch screw fixation had lower failure displacement than did locking plate fixation. No statistically significant differences were found in failure stiffness, yield stiffness (p = .655), yield load (p = .142), or ultimate load between the 2 fixation techniques. Cannulated headless variable-pitch screw fixation resulted in better failure displacement than locking plate fixation in a cadaveric talus model and could be considered a viable option for talus fracture fixation. Headless, fully threaded, variable-pitch screw fixation has inherent advantages compared with locking plate fixation, because it might cause less damage to the articular surface and can compress the fracture for improved reduction. Additionally, plate fixation can increase the risk of avascular necrosis owing to the wider incision and dissection of soft tissues.

  13. Factors influencing success of cement versus screw-retained implant restorations: a clinical review

    Directory of Open Access Journals (Sweden)

    Ahmad Manawar

    2012-10-01

    Full Text Available Aim: As more and more dental practitioners are focusing on implant-supported fixed restorations, some clinicians favor the use of cement retained restorations while others consider screw retained prosthesis to be the best choice. Discussion: In screw-retained restorations, the fastening screw provides a solid joint between the restoration and the implant abutment, while in cement-retained prostheses the restorative screw is eliminated to enhance esthetics, occlusal stability, and passive fit of the restorations. The factors that influence the type of fixation of the prostheses to the implants like passivity of the framework, ease of fabrication, occlusion, esthetics, accessibility, retention and retrievability are discussed in this article with scientific studies demonstrating superior outcomes of one technique over another. Screwretained implant restorations have an advantage of predictable retention, retrievability and lack of potentially retained subgingival cement. However, a few disadvantages exist such as precise placement of the implant for optimal and esthetic location of the screw access hole and obtaining passive fit. On the other hand, cement retained restorations eliminate unesthetic screw access holes, have passive fit of castings, reduced complexity of clinical and lab procedures, enhanced esthetics, reduced cost factors and non disrupted morphology of the occlusal table. Conclusion: This article compares the advantages, potential disadvantages and limitations of screw and cement retained restorations and their specific implications in the most common clinical situation.

  14. The use of bovine screws to promote bone formation using a tibia model in dogs

    Science.gov (United States)

    Bianchini, Marco Aurélio; Pontual, Marco Antônio B; Bez, Leonardo; Benfatti, César Augusto M; Boabaid, Fernanda; Somerman, Martha J; Magini, Ricardo S

    2013-01-01

    The objective of this study was to evaluate the use of a unique resorbable bovine bone screw, to stimulate bone formation. Bovine bone screws were inserted in the tibia beagle dogs. Each animal received 8 screws, divided into Groups A (screws + no membranes), B (screws + titanium reinforced membranes) and C (bone defects treated with autogenous bone grafts). Animals were sacrificed at 2, 4 and 6 months. New bone was measured with a periodontal probe and reported an average of 7.4 mm in vertical bone gain for Group B, 3.6 mm for Group A and 1.7 mm for Group C. Submission to Kruskal-Wallis test showed statistical differences between groups (p<0,05). Histological examination revealed an intimate contact between the newly formed bone and the resorbing bone screws. Conclusion: Bovine bone screws provide environment for new bone formation and thus may provide an alternative therapy for enhancing bone formation vertically, including for regenerative procedures as well as prior to implant therapy. PMID:23058228

  15. Evaluations of Flow and Mixing Efficiency in the Kneading Disks of a Novel Tri-Screw Extruder

    Directory of Open Access Journals (Sweden)

    X. Z. Zhu

    2016-01-01

    Full Text Available The forward or backward stagger angles of the kneading disks have great effects on configures of the special center region along axial length in a novel tri-screw extruder. In this paper, the flow and mixing of a nonNewtonian polyethylene in kneading disks of a tri-screw extruder were simulated using three-dimensional finite element modeling based on mesh superposition technique. Three types of kneading disks, neutral stagger, staggered 30° forward and staggered 30° reverse were considered for the tri-screw extruder. The effects of stagger angles of kneading disks on the flow pattern in the tri-screw extruder were investigated. Moreover, at different stagger angles, the dispersive and distributive mixing efficiencies in the kneading disks of the tri-screw extruder and the twin-screw extruder were calculated and compared by means of mean shear rate, stretching rates, maximal stress magnitudes, mixing index, residence time distribution (RTD and logarithm of area stretch. It is found that increasing the stagger angles decreases the axial velocities of polymer melt in the center region for the tri-screw extruder. The staggered 30° reverse is relatively reasonable for the tri-screw extruder and neutral stagger for the twin-screw extruder for the mixing efficiency. In comparison, the kneading disks in the tri-screw extruder have higher distributive and dispersive mixing efficiencies than those in the twin-screw extruder with the same stagger angles.

  16. 髂骨螺钉在成人腰椎骨盆固定术中的置钉路径及参数分析%Pelvic fixation paths and nailing parameter analysis on iliac screws in the adult lumbar spine

    Institute of Scientific and Technical Information of China (English)

    臧振华; 金昌洙; 张平

    2015-01-01

    ObjectiveToexplore the approach of iliac screw in lumbar vertebra pelvis arthrodesis. Methods Randomly selected 20 pelvic CT scan images of male and female separately, by reconstruction of 64 row spiral CT thin layer scanning image converted into 3D images. Firstly, you can select the nail screws O as entry point. Respectively from point O to the anterior superior, anterior inferior and upper edge of the acetabulum of the pelvis 3.5 mm cut, three cutting plane (OX, OY, OZ) were obtained, measured the length and width of each screw channel plane.ResultsThe narrowest diameter of three cutting plane (OX, OY, OZ) were more than 7 mm, all can be implanted iliac screw. Nail length range: Male OX plane (101.0±22)mm, OY plane (122.3±6.5)mm, OZ plane (110.8±9.0)mm; women OX plane (92.9±23.9)mm, OY plane (113.0±11.7)mm, OZ plane (110.6±11.2)mm. Statistical results also showed that there were no significance in the deflection angle of tailward and outward declination angle of screw channel between females and males (P>0.05).ConclusionThrough the pelvis three cutting plane (OX, OY, OZ) are permitted to implant screw. Through anterior inferior iliac spine (OY) is theoretically better iliac screw inserted position in the fixation of lumbar sacral vertebra pelvis.%目的:探讨腰椎骨盆融合术中髂骨螺钉入路。方法随机抽调进行过CT骨盆扫描的男女成年患者图像各20份,将其64排CT薄层图像重建转换为三维立体图像。选取可以进钉的螺钉入点O,从O点分别向髂前上棘、髂前下棘、髋臼上缘最高点处切割骨盆,得出3个切割平面(OX、OY、OZ),测量每个平面的钉道长度及宽度。结果3个切割平面(OX、OY、OZ)在最窄横径超过7 mm的条件下,均可以置入髂骨钉。钉长范围为:男性OX平面为(101.0±22)mm,OY平面为(122.3±6.5)mm,OZ平面为(110.8±9.0)mm;女性OX平面为(92.9±23.9)mm,OY平面为(113.0±11.7)mm,OZ

  17. Bacterial adherence to titanium, poly-L-lactic acid, and composite hydroxyapatite and poly-L-lactic acid interference screws.

    Science.gov (United States)

    Masini, Brendan D; Stinner, Daniel J; Waterman, Scott M; Wenke, Joseph C; Gerlinger, Tad L

    2012-01-01

    This study investigates a potential site of bacterial adherence, the implant surface, comparing titanium, poly-L-lactic acid (PLLA), and composite hydroxyapatite and poly-L-lactic acid (PLLA-HA) interference screws using a bioluminescent in vitro model. Interference screws of three materials, titanium (Arthrex, Naples, FL), bioabsorbable poly-L-lactic acid (BIORCI, Smith & Nephew, Andover, MA), and bioabsorbable composite hydroxyapatite and poly-L-lactic acid (BIORCI-HA, Smith & Nephew, Andover, MA) were immersed in a broth of bioluminescent Staphylococcus aureus. The screws were irrigated and then imaged with a photon-capturing camera system yielding a total photon count correlating with residual adherent bacteria. The titanium screws had the lowest mean total bacterial counts followed by the PLLA-HA screws and with the PLLA screws having the highest mean total counts. The difference in means between the titanium group and the PLLA group was statistically significant (p bacterial adherence than comparable bioabsorbable PLLA screws.

  18. Outcome of anterior cruciate ligament reconstruction with emphasis on sex-related differences.

    Science.gov (United States)

    Ahldén, M; Sernert, N; Karlsson, J; Kartus, J

    2012-10-01

    The aim of this retrospective study was to compare the results after arthroscopic anterior cruciate ligament (ACL) reconstruction using the four-strand semitendinosus-gracilis (ST/G) autograft in male (n=141) vs female (n=103) patients. The patients were operated on between 1996 and 2005, using interference screw fixation and drilling the femoral tunnel through the anteromedial portal. The pre-operative assessments and demographics, apart from age (males 29 years, females 26 years; P=0.02), were comparable at the time of surgery. At 25 (23-36) months post-operatively, no significant differences were found between the study groups in terms of anterior side-to-side knee laxity, manual Lachman test, Tegner activity level, Lysholm knee score, range of motion or donor-site morbidity. Both study groups improved significantly in most clinical assessments and functional scores compared with their pre-operative values. Two years after ACL reconstruction using ST/G autografts, there were no significant differences between male and female patients in terms of clinical outcome or functional scores.

  19. Error rate of multi-level rapid prototyping trajectories for pedicle screw placement in lumbar and sacral spine

    Institute of Scientific and Technical Information of China (English)

    Matjaz Merc; Igor Drstvensek; Matjaz Vogrin; Tomaz Brajlih; Tomaz Friedrich; Gregor Recnik

    2014-01-01

    Objective:Free-hand pedicle screw placement has a high incidence of pedicle perforation which can be reduced with fluoroscopy,navigation or an alternative rapid prototyping drill guide template.In our study the error rate of multi-level templates for pedicle screw placement in lumbar and sacral regions was evaluated.Methods:A case series study was performed on 11 patients.Seventy-two screws were implanted using multilevel drill guide templates manufactured with selective laser sintering.According to the optimal screw direction preoperatively defined,an analysis of screw misplacement was performed.Displacement,deviation and screw length difference were measured.The learning curve was also estimated.Results:Twelve screws (17%) were placed more than 3.125 mm out of its optimal position in the centre of pedicle.The tip of the 16 screws (22%) was misplaced more than 6.25 mm out of the predicted optimal position.According to our predefined goal,19 screws (26%) were implanted inaccurately.In 10 cases the screw length was selected incorrectly:1 (1%) screw was too long and 9 (13%) were too short.No clinical signs of neurovascular lesion were observed.Learning curve was insignificantly noticeable (P=0.129).Conclusion:In our study,the procedure of manufacturing and applying multi-level drill guide templates has a 26% chance of screw misplacement.However,that rate does not coincide with pedicle perforation incidence and neurovascular injury.These facts along with a comparison to compatible studies make it possible to summarize that multi-level templates are satisfactorily accurate and allow precise screw placement with a clinically irrelevant mistake factor.Therefore templates could potentially represent a useful tool for routine pedicle screw placement.

  20. Bicortical screw fixation of distal fibula fractures with a lateral plate: an anatomic and biomechanical study of a new technique.

    Science.gov (United States)

    Milner, Brenton F; Mercer, Deana; Firoozbakhsh, Keikhosrow; Larsen, Kenna; Decoster, Thomas A; Miller, Richard A

    2007-01-01

    One of the potential drawbacks of lateral plating of distal fibula fractures is less than satisfactory fixation of unicortical screws commonly placed in the distal fragment to avoid implant penetration of the ankle joint. This study examines the anatomy of the distal fibula, proposes new techniques for bicortical screw fixation and radiographic evaluation of screw placement, and compares pullout strength of unicortical versus bicortical screws in this area. Sixteen pairs of human cadaver feet were used in this study. It was found that a large percentage of the surface area of the distal fibula is nonarticular and that the distal fibula could be divided into 3 zones with distinct anatomic features. Zone I is defined as the distal most 1.5 cm of the fibula, zone II is the next 1 cm of fibula proximal to zone I, and zone III is defined as the fibula above the ankle joint, starting at just over 2.5 cm proximal to the tip of the fibula. We determined a safe corridor for bicortical screw placement by means of a lateral plate in each zone. An improved radiographic view is described for confirmation of extraarticular screw placement. Screw pullout testing was performed on 8 pairs of fresh-frozen human cadaver fibulas. In both zone I and zone II, the bicortical screw fixation was significantly stronger than the unicortical screw fixation. In zone I, the average pullout strength for the bicortical screw fixation was 2.3 times higher than the unicortical screw fixation. In zone II, the average pullout strength for the bicortical screw fixation was 3.3 times higher than the unicortical screw fixation. This study shows that not only is bicortical screw placement in the distal fibula technically feasible, but it is also biomechanically stronger than unicortical placement in this area.

  1. Rotating Optical Tubes: An Archimedes' Screw for Atoms

    CERN Document Server

    Rsheed, Anwar Al; Aldossary, Omar M; Lembessis, Vassilis E

    2016-01-01

    The classical dynamics of a cold atom trapped inside a vertical rotating helical optical tube (HOT) is investigated by taking also into account the gravitational field. The resulting equations of motion are solved numerically. The rotation induces a vertical motion for an atom initially at rest. The motion is a result of the action of two inertial forces, namely the centrifugal force and the Coriolis force. Both inertial forces force the atom to rotate in a direction opposite to that of the angular velocity of the HOT. The frequency and the turning points of the atom's global oscillation can be controlled by the value and the direction of the angular velocity of the HOT. However, at large values of the angular velocity of the HOT the atom can escape from the global oscillation and be transported along the axis of the HOT. In this case, the rotating HOT operates as an Optical Archimedes' Screw (OAS) for atoms.

  2. [Mechanical circulatory assist using a miniaturized Archimedes screw].

    Science.gov (United States)

    von Segesser, L K; Bisang, B; Leskosek, B; Turina, M

    1991-01-01

    An axial flow blood pump (Archimedes screw) for intraarterial left ventricular assist was evaluated in comparison to standard roller pump left heart bypass (LHBP) in 13 bovine experiments (bodyweight 74 +/- 15 kg). Full systemic heparinization (ACT greater than 500 s) was used for LHBP in comparison to limited systemic heparinization (ACT greater than 180 s) for axial. A standard battery of blood samples was taken before and at regular intervals throughout perfusion: (table; see text) Transarterial access and relatively limited blood trauma appear to be the main advantages of the evaluated axial flow blood pump. However, the impossibility to assess the pump flow may be a major problem for the management of the failing left ventricle.

  3. Assessment of a percutaneous iliosacral screw insertion simulator

    CERN Document Server

    Tonetti, J; Girard, P; Dubois, M; Merloz, P; Troccaz, Jocelyne; 10.1016/j.otsr.2009.07.005

    2009-01-01

    BACKGROUND: Navigational simulator use for specialized training purposes is rather uncommon in orthopaedic and trauma surgery. However, it reveals providing a valuable tool to train orthopaedic surgeons and help them to plan complex surgical procedures. PURPOSE: This work's objective was to assess educational efficiency of a path simulator under fluoroscopic guidance applied to sacroiliac joint percutaneous screw fixation. MATERIALS AND METHODS: We evaluated 23 surgeons' accuracy inserting a guide-wire in a human cadaver experiment, following a pre-established procedure. These medical trainees were defined in three prospective respects: novice or skilled; with or without theoretical knowledge; with or without surgical procedure familiarity. Analysed criteria for each tested surgeon included the number of intraoperative X-rays taken in order to achieve the surgical procedure as well as an iatrogenic index reflecting the surgeon's ability to detect any hazardous trajectory at the time of performing said procedu...

  4. Computer-Aided Design System for CP Single-Screw Compressor

    Institute of Scientific and Technical Information of China (English)

    SHEN Jing-feng; YAO Fu-sheng

    2006-01-01

    To design various optimum parameters and simulate the working process of CP single-screw compressor,the Computer-Aided Design(CAD)system for the CP singlescrew compressor has been established.A new method based on computer graphics technology,database technology,object-oriented programming technology,and visual simulation technology has been adopted in this CAD system.The system has integrated solid modeling function with parameterization design function and animator simulation function based on analyzing the working principle of the CP single-screw compressor.The experimental results show fhat the CAD system for the CP single-screw compressor is practical and feasible.

  5. Subtrochanteric femur fracture after removal of screws for femoral neck fracture in a child.

    Science.gov (United States)

    Song, Kwang Soon; Lee, Si Wook

    2015-01-01

    Displaced femoral neck fractures are rare in children and are associated with a high rate of complications. Subtrochanteric fractures after cannulated screw fixation of femoral neck fractures in adults are well recognized, and there are several reports on the topic. However, there are no reports on complications related to hardware or subtrochanteric fractures after removal of the screws in the treatment of femoral neck fractures in children. Here we report the case of a 10-year-old boy who sustained a subtrochanteric fracture after the screw removal and healing that followed a femoral neck fracture.

  6. The use of twin screw extruders for feeding coal against pressures of up to 1500 PSI

    Science.gov (United States)

    Wiedmann, W.; Mack, W. A.

    1977-01-01

    Recent tests with a twin-screw, co-rotating extruder which was successfully used to convey and feed coal against pressures of up to 1500 psi are described. Intermeshing and self-wiping, co-rotating twin-screws give greatly improved conveying and pressure built-up capabilities and avoid hangup and eventual decomposition of coal particles in the screw flights. The conveying action of intermeshing, self-wiping, co-rotating extruder systems approaches that of a positive displacement pump. With this feature, it is possible to maintain very accurate control over all aspects of product conveyance in the extruder, i.e., intake, conveyance and pressure buildup.

  7. Analysis of Indicator Diagrams of a Water Injected Twin-shaft Screw-type Expander

    OpenAIRE

    Nikolov, Alexander; Brümmer, Andreas

    2016-01-01

    Twin-shaft screw-type expanders offer a high potential for energy conversion in the lower and medium power range, for instance as expansion engines in Rankine cycles for exhaust heat recovery. With regard to minimizing internal leakages and lubricating moving machine parts, an auxiliary liquid or liquid working fluid can be fed to the screw expander. In this paper, indicator diagrams of a twin-shaft screw-type expander prototype designed at the Chair of Fluidics at TU Dortmund University are ...

  8. Pedicale screw system plus ACPC perfusion to treat fractures of thoracolumbar vertebrae

    Institute of Scientific and Technical Information of China (English)

    2001-01-01