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Sample records for dynamic hip screw

  1. Pseudoaneurysm of profunda femoris artery following dynamic hip screw fixation for intertrochanteric femoral fracture

    Institute of Scientific and Technical Information of China (English)

    Shailendra Singh; Sumit Arora; Ankit Thora; Ram Mohan; Sumit Sural; Anil Dhal

    2013-01-01

    Dynamic hip screw fixation is a commonly performed procedure for internal fixation of intertrochanteric femoral fractures.Arterial injury following the operative fixation is a rare but serious event.We present a patient who developed pseudoaneurysm of profunda femoris artery after internal fixation of intertrochanteric fracture with a dynamic hip screw.The diagnosis was confirmed by angiographic study and it was successfully treated by coil embolization.

  2. Dynamic Hip Screw Compared to Condylar Blade Plate in the Treatment of Unstable Fragility Intertrochanteric Fractures

    Directory of Open Access Journals (Sweden)

    CK Yong

    2009-05-01

    Full Text Available Dynamic hip screw (DHS fixation is considered standard treatment for most intertrochanteric fractures. However, excessive sliding at the fracture site and medialisation of femoral shaft may lead in fixation failure. In contrast, fixed- angled 95° condylar blade plate (CBP has no effective dynamic capacity and causes little bone loss compared to DHS. We compared the outcome of 57consecutive unstable intertrochanteric fragility fractures treated with these two fixation methods. CBP instrumentation is more difficult requiring longer incision, operating time and higher surgeon- reported operative difficulty. The six month post-operative mortality rate is 16%. Post-operative Harris hip scores were comparable between the two methods. Limb length shortening more than 20 mm was 6-fold more common with DHS. In elderly patients with unstable intertrochanteric fragility fractures, fixed angled condylar blade plate appears to be a better choice than dynamic hip screws for preventing fixation failures.

  3. Comparison and analysis of reoperations in two different treatment protocols for trochanteric hip fractures - postoperative technical complications with dynamic hip screw, intramedullary nail and Medoff sliding plate.

    Science.gov (United States)

    Paulsson, Johnny; Stig, Josefine Corin; Olsson, Ola

    2017-08-24

    In treatment of unstable trochanteric fractures dynamic hip screw and Medoff sliding plate devices are designed to allow secondary fracture impaction, whereas intramedullary nails aim to maintain fracture alignment. Different treatment protocols are used by two similar Swedish regional emergency care hospitals. Dynamic hip screw is used for fractures considered as stable within the respective treatment protocol, whereas one treatment protocol (Medoff sliding plate/dynamic hip screw) uses biaxial Medoff sliding plate for unstable pertrochanteric fractures and uniaxial Medoff sliding plate for subtrochanteric fractures, the second (intramedullary nail/dynamic hip screw) uses intramedullary nail for subtrochanteric fractures and for pertrochanteric fractures with intertrochanteric comminution or subtrochanteric extension. All orthopedic surgeries are registered in a regional database. All consecutive trochanteric fracture operations during 2011-2012 (n = 856) and subsequent technical reoperations (n = 40) were derived from the database. Reoperations were analysed and classified into the categories adjustment (percutaneous removal of the locking screw of the Medoff sliding plate or the intramedullary nail, followed by fracture healing) or minor, intermediate (reosteosynthesis) or major (hip joint replacement, Girdlestone or persistent nonunion) technical complications. The relative risk of intermediate or major technical complications was 4.2 (1.2-14) times higher in unstable pertrochanteric fractures and 4.6 (1.1-19) times higher in subtrochanteric fractures with treatment protocol: intramedullary nail/dynamic hip screw, compared to treatment protocol: Medoff sliding plate/dynamic hip screw. Overall rates of intermediate and major technical complications in unstable pertrochanteric and subtrochanteric fractures were with biaxial Medoff sliding plate 0.68%, with uniaxial Medoff sliding plate 1.4%, with dynamic hip screw 3.4% and with intramedullary nail 7.2%. The

  4. SURGICAL MANAGEMENT OF INTERTROCHANTERIC FRACTURES : A STUDY USING DYNAMIC HIP SCREW AND PROXIMAL FEMORAL NAIL

    Directory of Open Access Journals (Sweden)

    Venkateswara Rao

    2015-08-01

    Full Text Available OBJECTIVES: The aim of this study was to compare the outcome of intertrochanteric fractures treated with Dynamic Hip Screw and Proximal Femoral nail. METHODS: This study was conducted on 80 cases of Intertrochanteric fractures of femur treated by a dynamic hip screw and proximal femoral nail. Patients were operated on standard fracture table under image intensifier control. RESULTS: The average age of the patient was 63.2 years. Most common mechanism of fracture was domestic fall. The unstable pattern was more common in old aged patients with higher grade of osteoporosis. The average blood loss was 240 and 320ml in PFN and DHS group respectively. In PFN there were more no. of radiation exposure intraoperatively. The average operating time for the patients treated with PFN was 100min as compared to 80 min in patients treated with DHS. No complications of non - union and infection. In the PFN group the amount of sliding on X - rays was less as compared to DHS. The patients treated with PFN started early ambulation as they had better Harris Hip Score in the early period (at 1 and 3 month. In the long term both the implant had almost similar functional outcomes. CONCLUSION: From the study, we concluded PFN is better alternative to DHS in management of intertrochanteric fractures but is technically difficult procedure and requires more expertise compared to DHS.

  5. Functional Recovery Following Pertrochanteric Hip Fractures Fixated with the Dynamic Hip Screw vs. the Percutaneous Compression Plate

    Directory of Open Access Journals (Sweden)

    Yocheved Laufer

    2005-01-01

    Full Text Available The Dynamic Hip Screw (DHS is currently the most frequently used implant for the treatment of pertrochanteric hip fractures. The Percutaneous Compression Plate (PCCP is a recently developed, alternative device that involves minimal invasive surgery. The objective of the present study was to compare functional recovery following these two surgical procedures. A total of 76 consecutive elderly subjects (mean age and standard deviation, 80.6 ± 5.5 following pertrochanteric hip fracture fixation were evaluated prospectively. Functional recovery was assessed 3 and 12 weeks and 2 years following surgery. Differences between groups 3 weeks postsurgery were found only in pain level during ambulation and in the weight-bearing capability of the operated extremity, which were both in favor of the PCCP. By 3 months, both groups had improved in all measures, but did not reach their preinjury level of independence. However, the PCCP group ambulated with fewer assistive devices and demonstrated better recovery of basic activities of daily living (BADL. While the majority of the subjects from both groups ambulated independently 2 years postsurgery, the PCCP group exhibited less pain during ambulation, was more independent in ADL, and required fewer assistive devices for ambulation. To summarize, the PCCP presents enhanced short- and long-term recovery of functional abilities in comparison to DHS. However, given the limited number of patients, further studies are necessary to substantiate these results.

  6. A new technique for insertion of barrel plate over dynamic hip/compression lag screw:a case report

    Institute of Scientific and Technical Information of China (English)

    Sameer Naranje; Vivek Trikha

    2012-01-01

    Dynamic hip/compression screw (DHS/DCS) is one of the most commonly performed surgeries in orthopaedic practice.Sliding barrel plate over the DHS/DCS lag screw is one of the very crucial and at times uncomfortable and time consuming steps of DHS/DCS surgery especially when it comes to inexperienced surgeons and residents.Also in developing countries where not all standard instrumentation is always available,this crucial step becomes more time consuming.Here we present a case report of 58-year-old male patient with intertrochanteric fracture,in which we used a new device for insertion of barrel plate over DHS/DCS lag screw and found that a small DHS/DCS lag screw extension (sliding jig of barrel plate)can be very helpful to slide barrel plate over the DHS/DCS lag screw.

  7. Shepherd's Crook Deformity of Polyostotic Fibrous Dysplasia Treated with Corrective Osteotomy and Dynamic Hip Screw

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    Wei-Jen Chen

    2005-07-01

    Full Text Available Fibrous dysplasia, a condition in which the skeleton fails to develop normally, is characterized by fibroblastic stroma and immature bone. Bowing of the long bones occurs frequently in the polyostotic form, and stress fractures often result. Shepherd's crook deformity is a characteristic feature of fibrous dysplasia. The goal of its treatment is to obtain normal walking ability and relieve pain due to pathologic fracture secondary to the deformity; however, correction of the deformity is a surgical challenge. We present 2 cases of shepherd's crook deformity treated with corrective osteotomy and a dynamic hip screw. Both cases showed good bone healing and no recurrent deformity. The gross deformities were corrected, and both patients were pain-free after operation.

  8. Outcomes of osteoporotic trochanteric fractures treated with cement-augmented dynamic hip screw

    Directory of Open Access Journals (Sweden)

    Rakesh Kumar Gupta

    2012-01-01

    Full Text Available Background: Dynamic hip screw (DHS has been the standard treatment for stable trochanteric fracture patterns, but complications of lag screw cut out from a superior aspect, due to inadequate bone anchorage, occur frequently in elderly osteoporotic patients. Polymethylmethacrylate (PMMA has been used as an augmentation tool to facilitate fixation stability in cadaveric femora for biomechanical studies and in pathological fractures. However, there are very few reports on the utilization of PMMA cement to prevent these complications in fresh intertrochanteric fractures. A prospective study was conducted to evaluate the outcome and efficacy of PMMA augmented DHS in elderly osteoporotic patients with intertrochanteric fractures. Materials and Methods: The study included 64 patients (AO type31-A2.1 in eight, A2.2 in 29, A2.3 in 17 patients, and 31-A3.1 in five, A3.2 in three, and A3.3 in two patients with an average age of 72 years (60 − 94 years of which 60 were available for final followup. PMMA augmentation of DHS was performed in all cases by injecting PMMA cement into the femoral head with a custommade gun designed by the authors. The clinical outcome was rated as per the Salvati and Wilson scoring system at the time of final followup of one year. Results were graded as excellent (score > 31, good (score 24 − 31, fair (score 16 − 23, and poor (score < 16. Results: Fracture united in all patients and the average time to union was 13.8 weeks (range 12 − 16 weeks. At an average followup of 18 months (range 12 − 24 months, no incidence of varus collapse or superior screw cut out was observed in any of the patients in spite of weightbearing ambulation from the early postoperative period. There was no incidence of avascular necrosis (AVN or cement penetration into the joint in our series. Most of the patients were able to regain their prefracture mobility status with a mean hip pain score of 8.6. Conclusion: Cement augmentation of DHS appears

  9. Effectiveness of treatment of transtrochanteric fractures with Dynamic Hip Screws using minimally invasive access☆

    Science.gov (United States)

    de Abreu, Eduardo Lima; Sena, Caroline Brum; Saldanha Rodrigues Filho, Sergio Antonio

    2016-01-01

    Objective To analyze the short-term results from treating unstable intertrochanteric fractures with Dynamic Hip Screws (DHS), using a minimally invasive route, focusing on the functional aspects and complication and mortality rates of the method. Methods This was a prospective longitudinal study on 140 patients who underwent fixation of transtrochanteric fractures with the DHS system with a lateral minimally invasive access in the hip, between January and December 2013. The patients were evaluated pre and postoperatively (after six months of follow-up) by means of the Parker and Palmer mobility score. Women comprised 65.7% of the sample, and 54.3% of the fractures were on the right side. The patients’ mean age was 80 years, ranging from 60 to 93 years. Results We observed an overall decrease in the mobility score and an increase in the degree of dependence over the short term. However, we encountered only two deaths in the study sample and there were no cases of infection or nonunion. Conclusion Despite the efficacy of the treatment with DHS, with high rates of fracture consolidation and a low mortality rate, we noted that the patients still showed significant functional limitation at the follow-up six months after the operation. PMID:27069880

  10. Minimally invasive percutaneous compression plating versus dynamic hip screw for intertrochanteric fractures: a randomized control trial

    Institute of Scientific and Technical Information of China (English)

    Cheng Qiang; Huang Wei; Gong Xuan; Wang Changdong; Liang Xi; Hu Ning

    2014-01-01

    Objective:Intertrochanteric femur fracture is a common injury in elderly patients.The dynamic hip screw (DHS) has served as the standard choice for fixation; however it has several drawbacks.Studies of the percutaneous compression plate (PCCP) are still inconclusive in regards to its efficacy and safety.By comparing the two methods,we assessed their clinical therapeutic outcome.Methods:Atotal of 121 elderly patients with intertrochanteric femur fractures (type AO/OTA 31.A 1-A2,Evans type 1) were divided randomly into two groups undergoing either a minimally invasive PCCP procedure or a conventional DHS fixation.Results:The mean operation duration was significantly shorter in the PCCP group (55.2 min versus 88.5 min,P<0.01).The blood loss was 156.5 ml±18.3 ml in the PCCP group and 513.2 ml±66.2 ml in the DHS group (P<0.01).Among the patients treated with PCCP,3.1% needed blood transfusions,compared with 44.6% of those that had DHS surgery (P<0.01).The PCCP group displayed less postoperative complications (P<0.05).The mean American Society of Anesthesiologists score and Harris hip score in the PCCP group were better than those in the DHS group.There were no significant differences in the mean hospital stay,mortality rates,or fracture healing.Conclusion:Due to several advantages,PCCP has the potential to become the ideal choice for treating intertrochanteric fractures (type AO/OTA 31.A1-A2,Evans type 1),particularly in the elderly.

  11. Comparative study of the Ender method and Dynamic Hip Screw stabilization in the treatment of intertrochanteric fractures of the femur.

    Science.gov (United States)

    Walo, Roman; Semenowicz, Jacek; Grabowski, Marcin; Komarek, Marcin; Czuma, Przemysław

    2003-02-28

    Background. The aim of this retrospective study was to compare the results of two fixation devices (Ender rods in 118 patients and dynamic hip screw in 98 patients) for treatment of intertrochateric fractures of the hip. Material and methods. The two treatment groups were similar with respect to important preoperative variables such as age, coexisting disseases, bone quality and incidence of stable and unstable fractures. The following outcomes were assessed: quality of reduction, length of hospital stay, early mortality, reoperations, persistent pain at a knee or hip, decrease in range of motion of the knee and leg shortening. Results and conclusions. The subgroup analysis showed higher incidence of complications in patients with unstable type of fracture treated with Ender nailing. These complications included mainly valgus angulation and malrotation of the fracture, need for a secondary procedure due to loss of stabilization and knee pain. Intramedullary stabilization with Ender rods is not recommended in treatment of unstable intertrochanteric fractures of the femur.

  12. The dynamic locking blade plate, a new implant for intracapsular hip fractures: biomechanical comparison with the sliding hip screw and Twin Hook.

    Science.gov (United States)

    Roerdink, W H; Aalsma, A M M; Nijenbanning, G; van Walsum, A D P

    2009-03-01

    Internal fixation of intracapsular hip fractures results in a high failure rate with non-union and avascular necrosis being the two most important complications. In order to prevent these possible complications treatment should consist of an anatomical reduction and stable fixation by insertion of a low volume, dynamic implant, providing angular and rotational stability to the femoral head. According to these principles a new implant, the dynamic locking blade plate (DLBP) was designed for the fixation of intracapsular hip fractures. We performed a biomechanical analysis in synthetic bone to compare the rotational stability and cut out resistance of the DLBP with a conventional sliding hip screw (SHS) and the more recently developed Twin Hook. The rotational stability of the DLBP proved to be three times higher than the rotational stability of a SHS and two times higher than the Twin Hook. There was no major difference in cut out resistance between the different implants. The design of the DLBP and possible advantages with regard to the healing of an intracapsular hip fracture are discussed.

  13. The prognostic value of tip-to-apex distance (TAD index) in intertrochanteric fractures fixed by dynamic hip screw.

    Science.gov (United States)

    Sedighi, Ali; Sales, Jafar Ganjpour; Alavi, Sahar

    2012-11-01

    Intertrochanteric fractures (ITFs) are the most common type of fractures requiring surgical intervention. They also have the highest surgical mortality among orthopedic operations. Among the many different techniques used for fixation of this type of fracture, use of the Dynamic Hip Screw (DHS) has gained wide acceptance. This current study was designed to assess positive predictive value of tip-to-apex distance (TAD) index in the prognosis of patients treated with DHS. The study was designed according to a descriptive-analytic protocol, made up of 100 cases of ITFs caused by falling, treated in the Shohada Orthopedic Center, Tabriz, Iran. All patients underwent lateral and antero-posterior hip X-ray to measure TAD index. The cohort was followed for three months after DHS placement. Of a total of 100 cases (53 male, 47 female) with a mean age of 76.7 years (range 29-100 years), 43% had grade 4, 29% grade 3, 21% grade 5, 5% grade 2 and 2% grade 6 osteoporosis. The screw position was postero-inferior in 57%, central in 40% and superior in 3% of patients. Minimum and maximum TAD index were 20 and 28 mm, respectively. Mean TAD was 23.5 mm. There were no post-operative complications in 84% of cases. Screw failure was the most common complication in the remaining 16% of patients. The study shows a statistically significant correlation between TAD index and cut-off rate in patients with intertrochanteric fractures of femoral bone treated by DHS. This validates the use of TAD index in determining the prognosis of patients treated by DHS.

  14. Increased Fracture Collapse after Intertrochanteric Fractures Treated by the Dynamic Hip Screw Adversely Affects Walking Ability but Not Survival

    Directory of Open Access Journals (Sweden)

    Christian Fang

    2016-01-01

    Full Text Available In osteoporotic hip fractures, fracture collapse is deliberately allowed by commonly used implants to improve dynamic contact and healing. The muscle lever arm is, however, compromised by shortening. We evaluated a cohort of 361 patients with AO/OTA 31.A1 or 31.A2 intertrochanteric fracture treated by the dynamic hip screw (DHS who had a minimal follow-up of 3 months and an average follow-up of 14.6 months and long term survival data. The amount of fracture collapse and shortening due to sliding of the DHS was determined at the latest follow-up and graded as minimal (2 cm. With increased severity of collapse, more patients were unable to maintain their premorbid walking function (minimal collapse = 34.2%, moderate = 33.3%, severe = 62.8%, and p=0.028. Based on ordinal regression of risk factors, increased fracture collapse was significantly and independently related to increasing age (p=0.037, female sex (p=0.024, A2 fracture class (p=0.010, increased operative duration (p=0.011, poor reduction quality (p=0.000, and suboptimal tip-apex distance of >25 mm (p=0.050. Patients who had better outcome in terms of walking function were independently predicted by younger age (p=0.036, higher MMSE marks (p=0.000, higher MBI marks (p=0.010, better premorbid walking status (p=0.000, less fracture collapse (p=0.011, and optimal lag screw position in centre-centre or centre-inferior position (p=0.020. According to Kaplan-Meier analysis, fracture collapse had no association with mortality from 2.4 to 7.6 years after surgery. In conclusion, increased fracture collapse after fixation of geriatric intertrochanteric fractures adversely affected walking but not survival.

  15. Hollow-Bone-Graft Dynamic Hip Screw Can Fix and Promote Bone Union after Femoral Neck Fracture: an Experimental Research

    Directory of Open Access Journals (Sweden)

    Jia-zuo SHEN, Jian-fei YAO, Da-sheng LIN, Ke-jian LIAN, Zhen-qi DING, Bin LIN, Zhi-min GUO, Ming-hua ZHANG, Qiang LI, Lin LI, Peng QI

    2012-01-01

    Full Text Available Background: Delayed bone union, nonunion or osteonecrosis often occur after femoral neck fractures in young adults. Secondary bone healing requires strong internal fixation, intramedullary pressure reduction and early functional exercise.Objective: To compare bone healing of femoral neck fractures treated with hollow-bone-graft dynamic hip screws (Hb-DHS and standard dynamic hip screws (DHS in an animal model.Design: Testing of specifically designed fixation devices in a pig animal model.Interventions/Methods: We designed Hb-DHS and DHS devices appropriate to the femoral neck and head of experimental animals and used them in eight pigs (4-month-old, male or female, 30-40 kg/each. Under anesthesia, we induced medium neck type, Garden III type femoral neck fractures in each pig with fracture gaps of 0.5 mm and then fixed each left femur with Hb-DHS and each right femur with DHS. We assessed the animals radiographically and by postmortem visual appraisal of evidence of bone healing 8 and 16 weeks postoperatively.Results: There were significant differences in radiographic and general findings between the Hb-DHS and DHS groups at weeks 8 and 16 postoperatively. We found statistically significant differences between the Hb-DHS and DHS groups in bone healing scores, trabecular bone volume percentage and bone mineral density as assessed on plain radiographs and computed tomography images (P < 0.05. There were also significant differences between the Hb-DHS and DHS groups in postmortem visually assessed indicators of bone healing at both 8 and 16 weeks postoperatively.Conclusions: The Hb-DHS device promotes femoral neck bone union, stimulates trabecular bone formation, increases BMD and has advantages over DHS for internal fixation of femoral neck fractures. This animal experiment will contribute to developing optimal treatment for femoral neck fractures in young adults.

  16. Comparison of outcomes following uncemented hemiarthroplasty and dynamic hip screw in the treatment of displaced subcapital hip fractures in patients aged greater than 70 years.

    LENUS (Irish Health Repository)

    El-Abed, Kaldoun

    2012-02-03

    As health care costs increase, evaluating treatment methods in femoral neck fractures to determine the most effective treatment paradigm will become increasingly important. The current study compared two methods of treatment in similar cohorts of displaced femoral neck fractures. One hundred and twenty two patients were randomly assigned to two groups: In Group A, 62 patients were treated with a hemiarthroplasty. In group B, 60 patients were treated with dynamic screw fixation. Patients were evaluated at a minimum 3 year follow-up. Using the Matta functional hip score, 42% of group A and 70% of group B had good to excellent results. This difference was significant (p = 0.004). A significant agreement between physician assessment using the Matta score, and patient perception of outcome using the SF-36 scale was demonstrated (r = 0.64). No statistical difference between groups for revision surgery existed. Both physician based and patient based outcome scores favour retention and internal fixation of the femoral head in this cohort of patients at a short-term follow-up.

  17. COMPARATIVE STUDY BETWEEN PROXIMAL FEMORAL NAILING AND DYNAMIC HIP SCREW IN THE MANAGEMENT OF INTERTROCHANTERIC FRACTURES OF FEMUR

    Directory of Open Access Journals (Sweden)

    Penugonda Ravi Shankar

    2015-01-01

    Full Text Available AIMS AND OBJECTIVES : To determine the rate of union, complications, operative risks and functional outcomes in intertrochanteric fractures treated with DHS and PFN , To compare the results obtained and To compare the effectiveness of DHS and PFN in treatment of intertrochanteric fractures. RESULTS : In the present series of 24 cases of Intertrochanteric fractures were treated by proximal femoral nailing and dynamic hip screw, 12 cases in each. Out of 24 there were 13 male and 11 female. Minimum age was 36 years, maximum age 76 years with mean age of 59.25 years. Slip and fall accounted for 75% of cases. BOYD and GRIFFIN type II fracture accounted for 58.3% of cases. Mean duration of hospital stay was 26 days in both PFN and DHS groups. Length of incision was small 5 - 6cm in PFN group compared to 10 - 12cm in DHS group. Mean external blood loss 150ml in PFN group and 315 ml in DHS group. Mean time for full weight bearing was 11.5 weeks for PFN group and 14.3 weeks for DHS group. Radiological union was 12.3 weeks in PFN group and 15.5 weeks in DHS group. Good to excellent results were seen in 91.7% of cases in PFN group and 75% in DHS group. CONCLUSION : From the study, we consider PFN as better alternative to DHS in the treatment of intertrochanteric fractures but is technically difficult procedure and requires more expertise compared to DHS.As learning curve of PFN procedure is steep, with experience gained from each case operative time, radiation exposure and intraoperative complications can be reduced in each case of PFN

  18. 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

  19. 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

  20. Extracapsular hip fractures: fixation with a twin hook or a lag screw?

    Science.gov (United States)

    Olsson, O; Ceder, L; Lunsjö, K; Hauggaard, A

    2000-01-01

    The twin hook, which has 2 oppositely directed apical hooks, is an alternative to the lag screw for use with a 'dynamic plate' in the fixation of trochanteric hip fractures. In this prospective study lasting 1 year, 102 consecutive patients with trochanteric hip fractures were treated by 19 surgeons with either a twin hook or a lag screw combined with a conventional sliding hip screw plate or a Medoff sliding plate. Seven intraoperative errors were made with the twin hook but postoperative migration did not differ significantly between the 2 groups. Postoperative fixation failures were equally distributed between the 2 groups. The twin hook provides adequate fixation, which is comparable to that produced by a lag screw.

  1. 动力髋螺钉治疗股骨转子间骨折失效原因分析及处理%The Reason and Cope of Dynamic Motivation Hip Screw in Treating Hip Screw Rotor Femoral Fracture Failure

    Institute of Scientific and Technical Information of China (English)

    李启义; 高书图; 刘又文; 李建明; 王秋生; 王景辉

    2011-01-01

    目的:探讨动力髋螺钉(dynamic hip screw,DHS)治疗股骨转子间骨折失效的原因及对策.方法:2007年6月至2009年12月共收的15例股骨转子间骨折DHS内固定失效患者,通过对术前、术后X线片进行回顾,分析其失效原因并给予对症处理,其中10例重新行切开复位DHS再次固定,5例行全髋关节置换.结果:本组15例随访0.50-1.83 a,平均l a,根据髋关节功能Harris评分:优8例,良5例,中1例,差1例,优良率86.7%.结论:DHS内固定治疗股骨转子间骨折失效与术前适应证的选择及术中的操作技术有关,对于DHS内固定失效患者采取积极的再次手术治疗,术后可以获得较好的功能恢复和生活质量提高,疗效较满意.%Objective:To explore the dynamic motivation hip screw( hip screw rotor, while the femoral fracture failure treatment between the reasons and countermeasures. Methods:On June 2007 until 2009 on December 15 cases were gathered femoral fracture fixation DHS between rotor failure patients, through to the preoperative and postoperative X -ray are reviewed, analyzed its failure reason and give received alimta,including 10 routine to open reduction DHS again,5 underwent fixed total hip replacement. Results :Total 15 cases were followed up for 6 months -22 months,average 12 months, according to Harris hip score:optimal function in 8 cases, good in 5 cases,middle in 1 case, the difference in 1, dykes 86.7%. Conclusion: DHS internal fixation for femoral fracture failure between rotor with preoperative indications selection and art of operation for about technology, while the internal fixation failure patients take actively secondary surgery, and can obtain a good functional recovery and life quality improvement,curative effect is satisfactory.

  2. 微创动力髋螺钉内固定治疗股骨转子间骨折的护理%The nursing for treatment of the intertrochanteric fracture with minitraumatic dynamic hip screws

    Institute of Scientific and Technical Information of China (English)

    郑关伦; 钟小会; 杨益琼; 杨继录; 蒯娟; 李彤

    2012-01-01

    To promote successful rehabilitation after minimally invasive dynamic hip screw fixation of intertrochanteric fractures of the patients. Methods 68 cases of minimally invasive dynamic hip screw fixation of intertrochanteric fracture patients perioperative rehabilitation and care. Results Follow-up of 6 ~ 26 months, successful rehabilitation of the whole group, no nonunion and deformity. Conclusion Preoperative psychological nursing and the feasible rehabilitation program, early postoperative right limb and systemic functional rehabilitation exercise, guide early off-bed activities, is the key to successful rehabilitation of patients.%目的 促进微创动力髋螺钉内固定治疗股骨转子间骨折患者的术后顺利康复.方法 时68例微创动力髋螺钉内固定治疗股骨转子间骨折患者进行围手术期康复训练与护理.结果 随访6~26个月,全组顺利康复,未见骨折不愈合及畸形.结论 术前做好心理护理并制定切实可行的康复计划,术后早期正确地进行患肢及全身功能的康复锻炼,指导早期离床活动,是患者顺利康复的关键.

  3. 动力髋螺钉治疗股骨转子间骨折84例疗效观察%Dynamic Hip Screw Rotor Treatment Between The Femoral Fracture 84 Cases Curative Effects

    Institute of Scientific and Technical Information of China (English)

    谷效斌

    2011-01-01

    目的:总结动力髋螺钉(DHS)治疗股骨转子间骨折临床经验.方法:使用闭合或开放复位,DHS内周定治疗股骨转子间骨折84例,其中男51例,女33例;年龄48~92岁,平均71岁.结果:84例患者随访6~24月,平均14月,所有病例骨愈合,愈合时间3~6月,平均4.5月.其中髋内翻畸形4例,内固定失效1例.结论:动力髋螺钉内固定是治疗股骨转子间骨折的有效方法.%Objective:Summary dynamic hip screw (DHS) treatment between the femoral fractures rotor clinical experience.Methods:Using closed or open reduction, DHS internal fixation for femoral fractures between 84 cases of rotor, including male 51 cases,female 33 cases;Age 48~92 years,average 71.Results:84 patients were followed up for 6~24 months,average 14 months,all cases bone healing,healing time is 3~6 months,an average of 4.5 months. Including hip cubitus varus within 4 cases,1 case fixation failure. Conclusion:Dynamic hip screw internal fixation is between the femoral fractures of the rotor treatment method.

  4. Dynamic Hip Screw Fixation Combined of Oral Medicine Treating Intertrochanteric Fracture%动力髋螺钉固定术配合口服中药治疗高龄股骨粗隆间骨折

    Institute of Scientific and Technical Information of China (English)

    徐爱民

    2012-01-01

    目的:探讨采用动力髋螺钉(DHS)固定术配合口服中药治疗高龄股骨粗隆间骨折的方法和疗效.方法:对2004年1月—2009年1月收治的股骨粗隆间骨折患者进行手术治疗.其中男25例,女21例,年龄65~83岁,平均年龄73岁,采用动力髋螺钉(DHS)固定术.结果:1例病人术后3天出现患肢深静脉血栓,经活血、溶栓治疗后恢复.2例因其他疾病死亡,43例骨折均全部愈合,已恢复原来生活能力,无内固定物松动及髋内翻畸形等并发症.结论:动力髋螺钉(DHS)固定术配合口服中药治疗高龄股骨粗隆间骨折具有操作简单、时间短、固定可靠、损伤小、出血少、骨折愈合率高、并发症少等优点,是值得推广应用的手术方法[1].%Objective:To investigate the method and effect of the dynamic hip screw ( DHS )fixation of intertrochanteric fracture. Methods; During January 2004-January 2009, patients admitted because of intertrochanteric fractures were treated surgically, including 25 males and 21 females, aged 65 to 83 years old, mean age was 73, using dynamic hip screw ( DHS ) fixation. Results: 3 days after surgery, 1 case limb deep vein thrombosis occurs, the blood circulation restored after thrombolytic therapy. 2 patients died due to other diseases,43 cases of fracture were all healed and returned to the original capacity, no loosening of internal fixation, or complications such as varus deformity. Conclusion: The dynamic hip screw ( DHS ) fixation combined with oral medicine treatment of intertrochanteric fracture is simple, treatment course is short, fixed and reliable, with less damage, less bleeding, high fracture healing rate, fewer complications, and is worthy of promoting application for the surgical method[1].

  5. 动力髋螺钉治疗老年股骨粗隆间骨折临床分析%Study on treatment of intertrochanteric fractures in aged patients with dynamic hip screw.

    Institute of Scientific and Technical Information of China (English)

    何斌; 赵光荣; 向秀根; 张绍伟; 沈力; 廖涛

    2012-01-01

    目的 探讨动力髋螺钉(DHS)治疗老年股骨粗隆间骨折的临床疗效.方法 2009年1月至2011年1月收治的54例老年股骨粗隆间骨折患者,采用动力髋螺钉DHS内固定治疗,评价其临床疗效.结果 随访6~18月,所有患者骨折均在术后3~8月愈合,参照Sanders髋关节创伤评分,优良率达88.9%,并发症发生率24.1%(13/54).结论 DHS治疗老年股骨粗隆间骨折临床疗效明显,可以早期功能锻炼,关节功能恢复满意,是老年股骨粗隆间骨折较为理想的治疗方法.%Objective To evaluate the therapeutic effects of treatment for intertrochanteric fractures in aged patients with dynamic hip screw. Methods Fifty four aged patients with intertrochanteric fractures( 17 males and 37 females, with an average age of 73. 8 years )were treated in this hospital during January 2009 to January 2011. All cases were followed up for 6 to 18 months ( with an average of 13 months ). Results All cases obtained bony union with average duration for fracture union of 4. 6 months( 3-8 months ). According to the criteria of Sanders'hip trauma scoring, the rate of excellent or good function recovery of hip joint was 88. 9% . The rate of postoperative complications was 24. 1 % ( 13/ 54 ). These complications were arrhythmia in 3 cases, lacunar infarction in 2 cases, postoperative psychiatric symptoms in 2 cases, hip varus deformity in 4 cases and fixation failure in 2 cases. Conclusions The application of dynamic hip screwT is one of effective medical device in treatment of intertrochanteric fractures in aged patients. It is worthy to be clinically applied particularly in primary hospitals.

  6. Dynamic hip screw for femoral intertrochanteric fractures%动力髋螺钉内固定治疗股骨粗隆间骨折30例临床分析

    Institute of Scientific and Technical Information of China (English)

    王继夫; 朱伟秀; 轩林

    2008-01-01

    Objective To investigate the results of dynamic hip screw (DHS) intemal fixation for the treatment of femoral intertrochanteric fractures. Methods Thirty patients with femoral intertroehanteric fractures treated with DHS internal fixation were enrolled in the study. The classification of fracture, operative methods, postoperative treatment and therapeutic results were assessed. The mean follow-up period was one year. Results All the patients completed the follow-up. Fractures healed up without coxa vara, external rotation or shortening deformity of the lower extremity in all patients. Good hip joint function was obtained in 86.7% of the patients. Conclusion DHS internal fixation is an ideal method for the treatment of femoral intertrochanteric fractures.%目的 探讨应用动力髋螺钉(DHS)内固定治疗股骨粗隆间骨折的疗效.方法 对DHS内固定治疗30例股骨粗隆间骨折的分类、手术方法、术后处理及疗效进行评价,且平均随访12个月.结果 30例骨折愈合.无髋内翻、下肢外旋及短缩畸形,患髋关节功能优良率达86.7%,疗效肯定.结论 DHS内固定是治疗股骨粗隆间骨折的理想方法.

  7. 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.

  8. Dynamic Hip Screw and Steel Wire in Treatment of Intertrohanteric Fractures of Femur for 25 Cases Analysis%动力髋螺钉加钢丝治疗股骨转子间骨折25例分析

    Institute of Scientific and Technical Information of China (English)

    李东镖; 黄强; 李琼

    2014-01-01

    Objective To study the curative ef ect of dynamic hip screw and wire in treatment of Intertrohanteric fractures of femur.Methods From January 2010 to October 2012,according to the Beijing military region general hospital classification fractureⅠ, II, Ⅲ A,when reamer dril ing the femoral neck screw hole and fracture again,useing DHS and steel wire to treat these 25 patients,which analyzed retrospectively.17 males and 8 females,average age (74.5+5.1).First,surgery with smal incision, then surgery with large incision.Observation of intraoperative bleeding,postoperative infection,postoperative complications, postoperative hip joint function,and so on. Results There were no wound infection,no venous thrombosis of lower limb and no shortening varus deformity of lower limb about these 25 cases.According to Harris score of hip joint,the score up to 87.5%.Conclusion Intertrohanteric fractures of femur and fracture again in the operation,the treatment of DHS and steel wire has many advantages,such as operation simply,fewer complications,fixation is firm.The treatment of DHS and steel wire is one of the ef ective methods for the treatment of Intertrohanteric fractures of femur.%目的:探讨动力髋螺钉加钢丝治疗股骨转子间骨折的临床疗效。方法对2010年1月~2012年10月收治的按北京军区总医院分型I、Ⅱ、ⅢA骨折,术中绞刀钻股骨颈螺钉孔再骨折时选用DHS加钢丝治疗的25例病例进行回顾性分析,其中男性17例,女性8例,平均年龄(74.5±5.1)岁。手术采用先小切口,再大切口。观察术中出血,术后感染,术后并发症,术后髋关节功能等情况。结果25例病例均未出现伤口感染,下肢静脉血栓形成,下肢缩短内翻畸形。髋关节按Harris评分,达到87.5%。结论股骨转子间骨折,手术中再次骨折,选用DHS加钢丝治疗,具有操作简单,并发症少,固定尚牢靠的优点,是治疗股骨转子间骨折的有效方法之一。

  9. Biomechanical evaluation of dynamic hip screw with bone cement augmentation in normal bone%骨水泥强化正常骨质DHS固定的生物力学研究

    Institute of Scientific and Technical Information of China (English)

    黎宁; 彭阿钦; 聂喜增; 李锋; 赵永涛; 毕靖博; 韩长伶

    2008-01-01

    背景:DHS是治疗股骨转子间骨折的标准内固定,对于伴有骨质疏松的骨折,容易发生拉力螺钉切割.国内外文献建议骨水泥强化DHS以达到坚强内固定,但是对于正常骨质,骨水泥强化是否有效还缺少报道.目的:选取正常骨密度的股骨转子间骨折标本,观察骨水泥强化对DHS固定的生物力学影响.设计、时间及地点:同一标本两侧对比观察实验,于2005-03/05在河北省骨科研究所生物力学实验室完成.材料:选取河北医科大学解剖教研室提供的成年男性防腐尸体双侧股骨上段标本.X射线证实无结核、畸形、肿瘤.方法:取成年男性防腐尸体双侧股骨上段标本24对48侧,制备A2型股骨转子间骨折模型.右侧标本行骨水泥强化DHS固定(在股骨头近端钉道用刮匙扩大.股骨头朝下,注入2mL低黏稠度骨水泥,拧入拉力螺钉,保持位置不变直至骨水泥凝固.置入套筒,拧紧尾钉适当加压,皮质骨螺钉固定钢板),为强化组;左侧行DHS常规固定,为对照组.两组标本进行弯曲强度试验及扭转强度试验.主要观察指标:两组标本的最大负荷及最大扭矩.结果:强化组最大负荷及最大扭矩与对照组比较,差异均无统计学意义[最大负荷分别为:(3852.1602±143.6031)N和(3702.9667±133.8601)N;最大扭矩分别为(15.5±2.6)N·m,(14.7±3.4)N·m, P>0.0⑤.结论:对于正常骨密度的股骨转子间骨折,骨水泥强化对DHS固定强度及骨折整体稳定性无显著的影响.%BACKGROUND: Dynamic hip screw (DHS) is a standard internal fixation for intertrochanteric fracture, whereas the patient combined with osteoporosis, cut-out incidence of lag screw is common. The articles in China and abroad indicate bone cement augmentation of DHS to achieve firm fixation. As for normal bone, no reports is published that whether bone cement augmentation is effective.OBJECTIVE: To investigate the biomechanics of DHS with bone cement augmentation for

  10. Iatrogenic Injury of Profunda Femoris Artery Branches after Intertrochanteric Hip Screw Fixation for Intertrochanteric Femoral Fracture: A Case Report and Literature Review

    Directory of Open Access Journals (Sweden)

    Nikolaos Patelis

    2014-01-01

    Full Text Available A case of arterial rupture of the profunda femoris arterial branches, following dynamic hip screw (DHS fixation for an intertrochanteric femoral fracture, is presented. Bleeding is controlled by coil embolization, but, later on, the patient underwent orthopedic material removal due to an infection of a large femoral hematoma.

  11. A Meta-analysis on comparing efficacy of percutaneous compression plate with dynamic hip screw in treating intertrochanteric hip fractures%经皮加压钢板与动力髋螺钉治疗股骨转子间骨折的Meta分析

    Institute of Scientific and Technical Information of China (English)

    顾家烨

    2016-01-01

    Objective To analyze the efficacy and safety of percutaneous compression plate (PCCP) with dynamic hip screw(DHS) in treating intertrochanteric hip fractures.Methods The domestic literatures related to clinical trials of treating intertrochanteric hip fractures with PCCP and DHS were collected by searching PubMed,OVID MEDLINE,the Chinese biomedical literature database,Wanfang database,Weipu database and CNKI in the years from 2000 to 2014.A Metaanalysis was performed using Stata 11.0 software.Results There were 12 literatures qualified including 1056 cases(506 cases in group PCCP and 550 cases in group DHS).Meta analysis showed that the patients in group PCCP had less operation time and blood loss during surgery,less major complications,shorter hospital stay and better recovery of hip joint function than those in group DHS (P<0.05).There were no differences in bone healing time and mortality after operation between two groups(P>0.05).Conclusion The efficacy of PCCP for treating intertrochanteric hip fractures is superior to that of DHS.%目的 分析经皮加压钢板(PCCP)和动力髋螺钉(DHS)治疗股骨转子间骨折的有效性和安全性.方法 检索PubMed、OVID MEDLINE、中国生物医学文献数据库、万方数据库、维普数据库和中国知网等2000-2014年PCCP和DHS治疗股骨转子间骨折的相关文献,采用Stata 11.0软件对其进行Meta分析.结果 本研究纳入12篇文献,共计1056例患者;其中,PCCP组506例,DHS组550例.Meta分析结果:与DHS组比较,PCCP组的手术用时短、术中出血少、术后主要并发症少、住院时间短、术后髋关节功能恢复较好(P<0.05);但两组骨折愈合时间和术后病死率并无统计学差异(P>0.05).结论 PCCP治疗股骨转子间骨折的临床疗效优于DHS.

  12. Fibular grafting with cannulated hip screw fixation in late femoral neck fracture in young adults

    Directory of Open Access Journals (Sweden)

    Goyal R

    2006-01-01

    Full Text Available Background: We reviewed the operative results of fibular bone graft with cannulated hip screw fixation in femoral neck fracture in young adults. Method: Sixteen young adults with femoral neck fracture were treated by fibular bone graft with cannulated hip screw fixation. All the fractures were more than 3 weeks old. Results: Results were assessed in 15 patients while one patient died due to complications not related to surgery. Union occurred in all 15 patients. One patient had intra-operative complication in the form of screw cut out with graft in the joint space. The average fallow up was 24.4 months. Out of 15 patients assessed clinico-radiologically 11 showed good results, 3 had fair while 1 had poor result. Conclusion: We conclude that this is a simple and cost effective procedure for late femoral fleck fracture in young adults with good results.

  13. Dynamic hip screw and Gamma nail fixation repair unstable intertrochanteric fracture:a three-dimensional finite element analysis%动力髋螺钉和Gamma钉置入固定不稳定股骨转子间骨折的三维有限元分析

    Institute of Scientific and Technical Information of China (English)

    黄晓微; 禹宝庆; 李泽湘; 敖荣广

    2015-01-01

    BACKGROUND:For unstable intertrochanteric fracture repair, there are two views:extramedul ary fixation or intramedul ary fixation. Theoretical y, intramedul ary fixation is in line with the principles of minimal y invasive, more mechanical and biological advantages. However, evidence-based medicine and related studies have shown that compared with the extramedul ary fixation, intramedul ary fixation did not reflect the proper theoretical advantage. OBJECTIVE:To compare the biomechanical performance of two kinds of internal fixation systems:dynamic hip screw and Gamma nail which commonly used in repair of intertrochanteric fractures by finite element method, and to evaluate the advantages and disadvantages of dynamic hip screw and Gamma nail in treatment of unstable intertrochanteric fracture. METHODS:Three-dimensional finite element model of human femur unstable intertrochanteric fractures (31-A2;AO fracture classification), and the three-dimensional finite element models of dynamic hip screw and Gamma nail were established respectively, and were fixed according to the requirement of orthopedic surgery. The reference load which the joint bearing was at the peak time in adult step state period with the body mass of 700 N was stimulated. The stress distribution of bone, bone-internal fixation model, nail or screw, the strain and deformation of fracture location on the surface of the bone and bone-internal fixation model, the stress distribution along the femur and the loading transfer condition along the internal fixator and the like were analyzed. RESULTS AND CONCLUSION:Dynamic hip screw and Gamma nail have good sliding compression features which could make the continuous and dynamical y axial compression of the fractured section. Under the load conditions, the displacement value of dynamic hip screw was larger. In the treatment of unstable intertrochanteric fracture, Gamma nail was stronger than dynamic hip screw. Two kinds of internal fixations al make the

  14. 髋动力锁定钢板、重建钉与动力髋钢板治疗高龄股骨转子间骨折患者的疗效分析%Effect of anatomical dynamic hip lock plate, proximal femoral nail, and dynamic hip screws in the treatment of subtrochanteric femoral fractures in elderly patients: a comparative study

    Institute of Scientific and Technical Information of China (English)

    许思亮; 朱智奇; 候明

    2012-01-01

    Objective To investigate the effect of anatomical dynamic hip lock plate (ADHLP), proximal femoral nail (PFN), and dynamic hip screws (DHS) in the treatment of subtrochanteric femoral fractures in elderly patients. Methods One hundred and four patients with subtrochanteric femoral fracture in our hospital were divided into three groups: the ADHLP group, the PFN group and the DHS group. The operation time, intraoperative bleeding, Harris score one month and 6, 12 months after surgery, the healing time and the complications were compared between the three groups. Results The operation time, intraoperative bleeding and fracture healing time in PFN group were significantly less than those in DHS and ADHLP group, P<0.05. In the threee groups, Harris scores 12 months after surgery showed statistically significant difference with the scores 1 month and 6 months after surgery, P<0.05. The incidence of complications in PFN group was significantly lower than that in the other two groups, P<0.05. Conclusion PFN is preferred for treating elderly patients with subtrochanteric femoral fracture than DHS and ADHLP, with shorter operation time, less intraoperative bleeding, faster fracture healing and lower complications.%目的 探讨髋动力锁定钢板、重建钉与动力髋钢板在高龄股骨转子间骨折患者中的疗效差别.方法 回顾性研究我院收治的股骨转子间骨折患者共104例,根据治疗方式不同分为髋动力锁定钢板(ADHLP)组、重建钉(PFN)组以及动力髋钢板(DHS)组.对比三组患者手术时间、术中出血术后1个月、6个月、12个月Harris评分、骨折愈合时间以及并发症发生情况.结果 PFN组患者手术时间、术中出血及骨折愈合时间显著低于DHS组及ADHLP组,结果比较差异有统计学意义(P<0.05).三组患者术后12个月Harris评分与术后1个月、6个月评分比较差异有统计学意义(P<0.05).PFN组患者术后并发症发生率显著低于另外两

  15. Postoperative pain after hip fracture is procedure specific

    DEFF Research Database (Denmark)

    Foss, Nicolai; Palm, H; Kehlet, H

    2009-01-01

    . Patients were stratified into four groups according to surgical procedure: screws or pins, arthroplasty, dynamic hip screw (DHS), and intra-medullary hip screw (IMHS). RESULTS: Cumulated pain levels were significantly different between surgical procedures both for hip flexion (P=0.002) and for walking (P=0...

  16. 动力髋螺旋刀系统与螺旋刀片抗旋髓内钉修复不稳定型股骨转子间骨折比较%Dynamic hip screw knife systemversus spiral blade anti-rotation intramedullary nail in the treatment of unstable intertrochanteric fractures

    Institute of Scientific and Technical Information of China (English)

    林勇; 林雪平; 阮张涛

    2015-01-01

    BACKGROUND:Anti-rotation intramedulary nail fixation for proximal femoral fractures replaces the femoral bearing axis, moves towards body axis relative to hip screw and dynamic ankle screw, enhances the anti-fatigue strength at the fracture site, supports the anti-varus and prevents the rotation of the proximal fracture site, and is suitable for the treatment of unstable fracture. OBJECTIVE:To comparatively observe the effects of dynamic hip screw knife system and minimaly invasive spiral blade anti-rotation intramedulary nail in the repair of unstable intertrochanteric fractures. METHODS: A total of 82 cases of unstable intertrochanteric fractures, who were treated in the Department of Orthopedics, First People’s Hospital of Shunde from January 2012 to January 2014, were selected in this study. The patients were equaly and randomly divided into two groups: dynamic hip screw knife system group and minimaly invasive spiral blade anti-rotation intramedulary nail group. Repair index, fracture healing time and the incidence of complications were compared between the two groups. RESULTS AND CONCLUSION:Healing time and repair index were significantly better in the minimaly invasive spiral blade anti-rotation intramedulary nail group than in the dynamic hip screw knife system group (P < 0.05). Complications appeared in five patients from the minimaly invasive spiral blade anti-rotation intramedulary nail group, with the incidence rate of 12%, and in ten patients from the dynamic hip screw knife system group, with the incidence rate of 24%. The incidence of complications was significantly lower in the minimaly invasive spiral blade anti-rotation intramedulary nail group than in the dynamic hip screw knife system group (P < 0.05). These data suggest that for patients with unstable intertrochanteric fracture, minimaly invasive spiral blade anti-rotation intramedulary nail can decrease the incidence of complications, elevate the safety of the repair method, and promote the

  17. 空心加压螺钉与动力髋螺钉螺旋刀片治疗股骨颈骨折的临床疗效及生物力学分析%Cannulated compression screw versus dynamic hip screw-blade in the treatment of femoral neck fractures

    Institute of Scientific and Technical Information of China (English)

    骆东; 孙大辉; 姚霁航; 杨凯; 张晓猛; 鞠维娜; 祁宝昌

    2016-01-01

    Objective To compare the curative effect and biomechanical performance of cannulated compression screw (CCS) and dynamic hip screw-blade (DHS-B) in the treatment of patients with femoral neck fracture.Methods Between February 2010 and February 2014,102 patients with femoral neck fracture were treated with CCS or DHS-B at our department.They were 54 males and 48 females,aged from 15 to 86 years.There were 30 subcapital fractures,51 transcervical ones and 21 base ones.CCS was used in 60 patients and DHS-B in 42.In-hospital data were collected retrospectively to compare the curative effects in 2 groups.Furthermore,femoral neck fracture models were established using 12 adult cadaveric femoral specimens.The 12 models were randomized into 2 equal groups (n =6).Group A was subjected to fixation by 3 CCSs and group B to fixation by DHS-B.The 2 groups were compared in terms of axial loading test,rotation test and destructive axial loading test.Results The operation time (59.4 ± 20.2 min),incision size (4.1 ±0.6 cm) and intraoperative blood loss (25.9 ±9.9 mL) in the CCS group were significantly less than those in the DHS-B group (88.6±22.9 min,12.1 ±1.2cmand 156.7±107.1 mL) (P <0.05).The Harris hip score for the DHS-B group (91.9±9.8) was significantly higher than that for the CCS group (87.2 ± 9.2) (P < 0.05).There were no significant differences between the 2 groups in hospital stay,partial weight-bearing time,or postoperative complications (P > 0.05).At 500 N vertical loading,the stress values at both medial and lateral sides of the femur in group A were significantly smaller than those in group B (P < 0.05).There were no significant differences between groups A and B in the average sinking displacement of femoral head or the torque at a torsion angle of 6° (P > 0.05).The maximum load in group A (2,135 ±120 N) was significantly smaller than that in group B (2,986 ± 98 N) (P < 0.05).Conclusion In treatment of femoral neck fracture,DHS-B fixation is

  18. 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.

  19. 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.

  20. The vertical hip fracture – a treatment challenge. A cohort study with an up to 9 year follow-up of 137 consecutive hips treated with sliding hip screw and antirotation screw

    Directory of Open Access Journals (Sweden)

    Enocson Anders

    2012-09-01

    Full Text Available Abstract Background Femoral neck fractures with a vertical orientation have been associated with an increased risk for failure as they are both axial and rotational unstable and experience increased shear forces compared to the conventional and more horizontally oriented femoral neck fractures. The purpose of this study was to analyse outcome and risk factors for reoperation of these uncommon fractures. Methods A cohort study with a consecutive series of 137 hips suffering from a vertical hip fracture, treated with one method: a sliding hips screw with plate and an antirotation screw. Median follow-up time was 4.8 years. Reoperation data was validated against the National Board of Health and Welfare’s national registry using the unique Swedish personal identification number. Results The total reoperation rate was 18%. After multivariable Logistic regression analysis adjusting for possible confounding factors there was an increased risk for reoperation for displaced fractures (22% compared to undisplaced fractures (3%, and for fractures with poor implant position (38% compared to fractures with adequate implant position (15%. Conclusions The reoperation rate was high, and special attention should be given to achieve an appropriate position of the implant.

  1. 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.

  2. 综合康复护理对股骨粗隆间骨折行DHS内固定术患者预后的影响%Effect of comprehensive rehabilitation interventions on the patients with intertrochanteric fracture of femur treated by dynamic hip screw internal fixation

    Institute of Scientific and Technical Information of China (English)

    钟巧艺; 陈思颖; 赵洁莲; 区海云; 何惠兰

    2011-01-01

    目的:探讨综合康复护理对股骨粗隆间骨折行动力髋螺钉(dynamic hip screw,DHS)内固定术患者预后的影响.方法:选择2008年9月-2009年9月本院收治的股骨粗隆间骨折行DHS内固定术的49例患者为对照组,选择2009年10月-2010年10月收治的58例患者为实验组.对照组给予常规护理,实验组采用综合康复护理,比较两组患者骨折愈合时间、住院时间、疗效及并发症的发生率.结果:实验组骨折愈合时间及住院时间短于对照组、疗效优于对照组、并发症的发生率低于对照组(均P<0.05).结论:股骨粗隆间骨折患者行DHS内固定术后采用综合康复护理,有利于缩短骨折愈合时间及住院时间,提高治疗效果,降低术后并发症的发生率,值得临床推广应用.%Objective To explore the influence of comprehenaive rehabilitation interventions on patients with intertrochanteric fracture of femur treated by DHS (dynamic hip screw) intemal fixation. Methods Forty-nine patients with intertrochanteric fracture of femur treated by DHS intemal fixation from September 2008 to September 2009 were selected as the control group. Fifty-eight patients with intertrochanteric fracture of femur treated by DHS intemal fixation from October 2009 to October 2010 were selected as the experimental group. The control group received conventional nuraing intervention, and the experimental group received comprehensive rehabilitation nursing interventions. Healing time, hospitalization time, clinical effect and incidence of complications were compared in the two groups. Results Hospitalization time, clinical effect in the experimental group was shorter than thoae in the control group; the clinical effect was better than that in the control Sroup; the incidence of complications was lower than that in the control group. Conclusion Comprehengive nursing intervention shortens healing time and hospitalization time, increases the therapy efficacy, and decreases the

  3. 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.

  4. 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.

  5. 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.

  6. Comparison of of Proximal Femoral Nail and Dynamic Hip Screw in Treatment of Subtrochanteric Unstable Fractures of Femur in Elder Patients%PFN与DHS治疗老年不稳定型股骨粗隆下骨折的疗效分析

    Institute of Scientific and Technical Information of China (English)

    沈翔; 倪江东; 张淑云; 易文辉; 贺建军; 唐长友; 熊湘彦; 刘小华; 宋德业

    2011-01-01

    比较PFN与DHS内固定治疗老年不稳定型股骨粗隆下骨折的预后及评其疗效.方法:2002年1月至2008年1月我科共收治老年不稳定型股骨粗隆下骨折患者129例,男59例,女70例,年龄51~86岁,平均61.7岁.随机选择PFN或DHS内固定,PFN组62例,DHS组67例.比较两组的手术时间、术中出血量、术后第二天CRp值、张力侧出现骨痂时间、骨折愈合时间、Harris评分等6项指标.结果:116例获得13~48个月的随访,平均18.7月,除手术时间及Harris评分无差异外,PFN组在术中出血量、术后第二天CRP值、张力侧出现骨痂时间、骨折平均愈合时间等方面与DHS组比较有显著优势(P<0.05).结论:PFN内固定创伤小、术后并发症率较低,可以成为治疗老年不稳定型股骨粗隆下骨折的主要方法.%Objective: To compare the prognosis of the proximal femoral nail (PFN) and the dynamic hip screw (DHS) in the treatment of subtrochanteric unstable fractures of femur in elder patients. Methods.- From January 2002 to January 2008, 129 patients were treated with unstable fractures of femur (59 males and 70 females) with an average age of 61.7 years ranging from 51 to 86 years. The patients were randomly divided into PFN group (n=62) and DHS group (n=67). The operative duration, volume of blood loss, CRP value of postoperative day, callus growth time, fracture healing time and Harris Hip Score were statistically analyzed and compared between the two groups. Results: A total of 116 cases were followed up for 13 to 48 months (average 18.7 months). There was no difference between the two groups in operative duration and Harris Hip Score. But compared with the DHS group, PFN group showed significant advantages in indicators of volume of blood loss, CRP value of postoperative day, callus growth time and fracture healing time (P<0.05). Conclusion: With the excellence of fewer trauma and complications, PFN treatment could be primarily used in treating the

  7. 髋关节动力螺钉和股骨近端髓内钉-螺旋刀片固定股骨转子间骨折的效果比较%Therapeutic effect of dynamic hip screw versus proximal femoral nail anti-rotation blade for intertrochanteric fractures

    Institute of Scientific and Technical Information of China (English)

    陈生文

    2012-01-01

    BACKGROUND: Dynamic hip screw (DHS) is the gold standard for clinical fixation of intertrochanteric fractures, and achieves certain effect. But proximal femoral nail anti-rotation (PFNA) blade is a new modified proximal femoral fixation system, which is used to solve the deficiencies of previous fixation. OBJECTIVE: To compare the clinical effect of DHS and PFNA blade for intertrochanteric fractures. METHODS: Totally 76 patients with intertrochanteric fractures were selected including 36 cases treated with DHS and 40 cases with PFNA. All the patients received operative treatment with common operative route. RESULTS AND CONCLUSION: Incidence rate of medical complication and deformity rate of hip joint in the PFNA group were lower than those in the DSH group (P< 0.05). The excellent and good rate of the hip function recovery was 78% (28/36) in the DSH group, and which in the PFNA group was 82% (33/40). The results showed that both the two method of DHS and PFNA have good clinic curative effect for the treatment of intertrochanteric fractures, but the PFNA has the advantages of simple operation, less bleeding, and reliable fixation.%背景:髋关节动力螺钉是临床固定股骨转子间骨折的金标准,取得了一定的疗效,而股骨近端髓内钉-螺旋刀片是经过改进的新型股骨近端髓内固定系统,它的运用解决了以往内固定的不足.目的:比较髋关节动力螺钉和股骨近端髓内钉-螺旋刀片治疗股骨转子间骨折的疗效.方法:76例股骨转子间骨折患者,其中36例用髋关节动力螺钉固定,40例用股骨近端髓内钉-螺旋刀片固定,均采用常规手术入路.结果与结论:股骨近端髓内钉-螺旋刀片组的髋部畸形率及并发症发生率均低于髋关节动力螺钉组(P < 0.05),髋关节动力螺钉组髋关节功能恢复优良率达78%(28/36),股骨近端髓内钉-螺旋刀片组为82%(33/40).结果可见两组治疗股骨转子间骨折均有满意的临床疗效,但是股骨近

  8. Treatment of benign pathological femoral neck or trochanteric lesions by using dynamic condylar screw or hip joint spanning external fixator%动力髁螺钉或超关节外固定支架治疗股骨颈和转子良性病损病理性骨折

    Institute of Scientific and Technical Information of China (English)

    张春林; 曾炳芳; 董扬

    2009-01-01

    目的 探讨继发于股骨颈和转子良性病损病理性骨折的治疗方法.方法 回顾性研究2002-2004年间治疗的25例股骨近端良性病损病理性骨折患者.采取病灶刮除、苯酚烧灼、自体或异体骨移植,然后根据病损涉及股骨近端范围的大小,选择采用动力髁螺钉(DCS)或超髋关节外固定支架进行固定.平均随访时间为2.5年(2~4年).结果 所有患者术后3~6个月影像学上均可见良好的骨性愈合.未见局部复发和缺血性股骨头坏死及感染、骨折等并发症.采用美国骨与软组织肿瘤学会(Musculoskeletal Tumor Society,MSTS)-87、MSTS-93和多伦多保肢评分(Toronto Extremity Salvage Score,TESS)系统进行功能评估,均为良好和优秀.结论 与单纯植骨、牵引、髋"人"字石膏支具等传统方法相比,DCS或超髋关节外固定支架是治疗股骨颈和转子良性病损病理性骨折的又一可靠方法.%Objective To investigate treatment method for existing and impending benign pathological femoral neck and trochanteric lesions.Methods A retrospective study wad done on 25 patients with benign proximal femur lesions treated between 2002 and 2004.All patients were treated with lesion curettage,cauterization,autografting and/or allografting.Then,dynamic condylar screw (DCS) or hip joint-span external fixator were selected according to the involved area of the lesion of the proximal femur.The duration of follow-up was mean 2.3 years (2-4 years).Results Sound bony union was seen on the radiographs of all patients by 3-6 months after surgery.There found no local recurrence or avascular necrosis of the femoral head,or complications like necrosis,infections or fractures.Function of the patients in the current series was graded excellent,assessed by the validated outcome measures MSTS-87,MSTS-93 and TESS lower extremity.Conclusion DCS or hip joint-span external fixator may be better alternative treatment of benign pathological femoral neck and

  9. 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.

  10. Internal fixations of proximal femoral nail antirotation versus that of dynamic hip screw for femoral intertrochanteric fracture%抗旋转型股骨近端髓内钉内固定与动力髋螺钉内固定治疗股骨转子间骨折的临床疗效对比观察

    Institute of Scientific and Technical Information of China (English)

    梁荣班; 赵佳; 卢珂恩; 谭宏昌

    2014-01-01

    Objective To explore and study the clinical effects of the internal fixations of proximal femoral nail antirotation(PFNA) and dynamic hip screw(DHS) for femoral intertrochanteric fracture.Methods 100 patients with femoral intertrochanteric fracture admitted into our hospital from April,2009 to April,2013 were selected as study objects and randomly and equally divided into two groups.50 patients (PFNA group) were treated by the internal fixation of PFNA,and the other 50 patients (DHS group) by the internal fixation of DHS.They were followed up for 9-18 months.The curative effects of both groups were observed and compared.Results The volumes of intraoperative bleeding and of the postoperative drainage were smaller and the postoperative weight-loading walking time and healing time were shorter in the PFNA group than in the DHS group.The Harris hip function scores were increased in both groups after the treatment; the hip function scores,motion ranges,and synthetic scores were increased more but the hip joint score of deformity less in the PFNA group than in the DHS group.The incidence of postoperative complications of the PFNA group was 6.0%,which was significantly lower than that of the DHS group (26.0%),with a statistical difference (P<0.05).Conclusions PFNA has better curative effects than DHS in the treatment of femoral intertrochanteric fracture and has greater comparative advantages in intraoperative bleeding volume,postoperative healing time,and weight-bearing walking time.Comparing with DHS treatment,PENA treatment causes fewer postoperative complications and recovers hip joint function better,so it can be the first treatment choice for patients with femoral intertrochanteric fracture.%目的 探究抗旋转型股骨近端髓内钉(PFNA)内固定与动力髋螺钉(DHS)内固定在股骨转子间骨折中的临床疗效.方法 选取自2009年4月至2013年4月我院收治的股骨转子间骨折患者100例,将其作为研究对

  11. Comparison of the effect of anatomical plate and dynamic hip screw for elderly patients with intertrochanteric fracture%解剖型钢板与髋动力螺钉治疗老年人股骨粗隆间骨折的疗效比较

    Institute of Scientific and Technical Information of China (English)

    沈俊玲

    2014-01-01

    Objective To compare the effect of anatomical plate and dynamic hip screw(DHS) for elderly patients with intertrochanteric fracture.Methods The clinical data of medical treatments for elderly patients with intertrochanteric fracture were retrospectively analyzed.36 cases received anatomical plate treatment were selected as observation group,and 34 cases received DHS were selected as control group.Results The operation time,intraoperative blood loss,postoperative length of stay(LOS) and the time of fracture healing in observation group were obviously shorter than those in control group(t =2.18,2.35,2.31,2.15,all P <0.05).In observation group,3 cases appeared postoperative complications,included 2 cases of pulmonary infection,and 1 case of varus deformity of hip joint.In control group,9 cases appeared postoperative complications,included 2 cases of pulmonary infection,4 cases of varus deformity of hip joint,2 cases of limb shortening deformity,and 1 case of deep venous thrombosis of lower extremity.The incidence rate of complication of the observation group was 8.33%,which was significantly lower than 26.47% of the control group (x2 =4.05,P < 0.05).The patients were followed up for 12 to 21 months after operation,average (16.7 ±4.2)months,the excellent and good rate of the function of postoperative hip joint in the observation group was 86.11%,which was significantly higher than 64.71% in the control group (x2 =4.36,P < 0.05).Conclusion Both anatomical plate and DHS have favorable effect on old patients with intertrochanteric fracture,and anatomical plate has advantages such as short operation time,a small amount of intraoperative bleeding,short postoperative LOS,short time of fracture healing,less postoperative complication,high excellent and good rate of the function of postoperative hip joint and etc,and it is preferably suitable for the comminuted fracture which cannot be cured by DHS.%目的 比较解剖型钢板与髋动力螺钉治疗老年人

  12. 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.

  13. Dynamic ultrasound of the external snapping hip syndrome

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Yun Sun; Song, Baek Yong; Paik, Sang Hyun; Lee, Tae Gyu; Yoon, Yong Kyu [Eulji Hospital, Eulji University School of Medicine, Deajeon (Korea, Republic of); Lee, Sung Moon [Keimyung University School of Medicine, Deagu (Korea, Republic of)

    2002-09-15

    Snapping hip syndrome has been described as a hip pain accompanied by an audible snapping during motion of the hip or while walking. The variable causes of its external, internal, and intra-articular origins have been described. The most common extemal snapping hip has been associated with a thickened posterior border of the iliotibial band or of the anterior border of the gluteus maximus muscle slipping over the greater trochanter. The aim of this study was to evaluate the dynamic ultrasound findings of external snapping hip syndrome with review of the literature. We studied 5 patients (7 cases) with external snapping hip and pain over the greater trochanter during walking or hip motion (3 males and 2 females, age range, 14-32 years; mean, 19 years). Two patients reported bilateral snapping hips.

  14. MANAGEMENT OF DISTAL FEMORAL FRACTURES USING DYNAMIC CONDYLAR SCREWS

    Directory of Open Access Journals (Sweden)

    Ambrish

    2015-11-01

    Full Text Available BACKGROUND Fractures of distal end of femur are complex injuries which are difficult to manage & are unstable and comminuted. Despite advances in implants treatment of distal femoral fractures remains a challenge. AIMS This study was done to analyze the functional outcome & complications associated with surgical management of fractures of distal end of femur in adults using Dynamic Condylar Screw (DCS. SETTINGS & DESIGN It was a prospective clinical study done at BMCH, Chitradurga. METHODS The present study included 25 patients with 13 Supracondylar and 12 Intercondylar fractures of femur. They were operated after stabilization using Dynamic Condylar Screw. RESULTS The study showed maximum presentation between 4th and 5th decade with mean age of 39.2 years with sex incidence of 11.5:1 (M:F. Mode of injury was RTA in 17, simple fall in 5, fall from height in 2 and assault in 1 patient. Patients presented to hospital within 0 to 4 days of injury. Left side was involved in 12 and right side in 13 cases. There were 9-A1, 3-A2, 1-A3, 2-C1, 8-C2 and 2-C3 fractures. Six patients had compound fracture. Patients were operated from 3 days to 40 days after admission at an average of 12.36 days. Results were found to be excellent in 8, good in 9, moderate in 3 and poor in 5 patients. Complication in form of valgus angulation, shortening, splintering of proximal femoral fragment, deep infection, Implant failure and lateral angulation at fracture site, Non-union with deep infection were noticed. Average range of knee flexion was 1040 and average time to radiological union was 13.42 weeks. CONCLUSION This study showed that DCS is a good method of treating closed type A1, A2, A3, C1 and C2 fractures. Type C3 and compound fractures treated by this method had more poor results. DCS provides rigid fixation and good purchase in osteoporotic bone. Early mobilization prevents knee stiffness.

  15. 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.

  16. Dynamic modelling and PID loop control of an oil-injected screw compressor package

    Science.gov (United States)

    Poli, G. W.; Milligan, W. J.; McKenna, P.

    2017-08-01

    A significant amount of time is spent tuning the PID (Proportional, Integral and Derivative) control loops of a screw compressor package due to the unique characteristics of the system. Common mistakes incurred during the tuning of a PID control loop include improper PID algorithm selection and unsuitable tuning parameters of the system resulting in erratic and inefficient operation. This paper details the design and development of software that aims to dynamically model the operation of a single stage oil injected screw compressor package deployed in upstream oil and gas applications. The developed software will be used to assess and accurately tune PID control loops present on the screw compressor package employed in controlling the oil pressures, temperatures and gas pressures, in a bid to improve control of the operation of the screw compressor package. Other applications of the modelling software will include its use as an evaluation tool that can estimate compressor package performance during start up, shutdown and emergency shutdown processes. The paper first details the study into the fundamental operational characteristics of each of the components present on the API 619 screw compressor package and then discusses the creation of a dynamic screw compressor model within the MATLAB/Simulink software suite. The paper concludes by verifying and assessing the accuracy of the created compressor model using data collected from physical screw compressor packages.

  17. Study of Bone-screw Surface Fixation in Lumbar Dynamic Stabilization

    Institute of Scientific and Technical Information of China (English)

    Yun-Gang Luo; Tao Yu; Guo-Min Liu; Nan Yang

    2015-01-01

    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(R) 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).This showed the description bone of the ROI in the static control group was greater than in the fixation groups.Under loading conditions,the pedicle screw maximum pull force was not significantly different between the bilateral and unilateral dynamic fixation groups (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.

  18. 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.

  19. Passive hip movement measurements related to dynamic motion during gait in hip osteoarthritis.

    Science.gov (United States)

    Baker, Matt; Moreside, Janice; Wong, Ivan; Rutherford, Derek J

    2016-10-01

    Reduced sagittal plane range of motion (ROM) has been reported in individuals with hip osteoarthritis (OA) both during walking and passive testing. The purpose of this study was to determine if a relationship exists between hip extension ROM recorded during gait and passive hip extension ROM in individuals with moderate and severe hip OA, in comparison to an asymptomatic group. Sagittal plane hip ROM was calculated using skin surface marker trajectories captured during treadmill walking at self-selected speed. Passive hip ROM was measured using standardized position and recording procedures with a goniometer. Sagittal plane extension, flexion, and overall ROM were measured dynamically and passively. A two-way mixed model analysis of variance determined significant differences between groups and between passive and dynamic ROM (α = 0.05). Pearson correlations determined relationships between passive and dynamic ROM. Significant group by ROM interactions were found for flexion and extension ROM (p passive ROM compared to the other groups and greater passive than dynamic ROM (p passive ROM existed between all three groups (p passive hip extension were found in the moderate (r = 0.596) and severe OA (r = 0.586) groups, and no correlation was found in the asymptomatic group (r = 0.139). Passive ROM explains variance in dynamic ROM measurements obtained during gait in individuals with moderate and severe hip OA which have implications for the design of treatment strategies targeting walking pathomechanics. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 34:1790-1797, 2016. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc.

  20. Comparative endurance testing of the Biomet Matthews Nail and the Dynamic Compression Screw, in simulated condylar and supracondylar femoral fractures

    OpenAIRE

    Davies Benjamin M; Davidson Jerome A; O'Connor-Read Laurence M; Matthews Michael G; Smirthwaite Paul

    2008-01-01

    Abstract Background The dynamic compression screw is a plate and screws implant used to treat fractures of the distal femur. The Biomet Matthews Nail is a new retrograde intramedullary nail designed as an alternative surgical option to treat these fractures. The objective of this study was to assess the comparative endurance of both devices. Method The dynamic compression screw (DCS) and Biomet Matthews Nail (BMN) were implanted into composite femurs, which were subsequently cyclically loaded...

  1. A screw-based dynamic balancing approach, applied to a 5-bar mechanism

    NARCIS (Netherlands)

    de Jong, Jan Johannes; van Dijk, Johannes; Herder, Justus Laurens

    2016-01-01

    Dynamic balancing aims to reduce or eliminate the shaking base reaction forces and moments of mechanisms, in order to minimize vibration and wear. The derivation of the dynamic balance conditions requires significant algebraic effort, even for simple mechanisms. In this study, a screw-based balancin

  2. Smallest Archimedean Screw: Facet Dynamics and Friction in Multiwalled Nanotubes.

    Science.gov (United States)

    Guerra, Roberto; Leven, Itai; Vanossi, Andrea; Hod, Oded; Tosatti, Erio

    2017-08-28

    We identify a new material phenomenon, where minute mechanical manipulations induce pronounced global structural reconfigurations in faceted multiwalled nanotubes. This behavior has strong implications on the tribological properties of these systems and may be the key to understand the enhanced interwall friction recently measured for boron-nitride nanotubes with respect to their carbon counterparts. Notably, the fast rotation of helical facets in these systems upon coaxial sliding may serve as a nanoscale Archimedean screw for directional transport of physisorbed molecules.

  3. A locked hip screw-intramedullary nail (cephalomedullary nail) for the treatment of fractures of the proximal part of the femur combined with fractures of the femoral shaft.

    Science.gov (United States)

    Alho, A; Ekeland, A; Grøgaard, B; Dokke, J R

    1996-01-01

    Twenty-seven patients with complex femoral fractures (combined shaft and proximal femoral fractures) were treated with a modified Grosse-Kempf slotted locking nail (cephalomedullary nail), wherein two screws were inserted in the hip. Four types of complex, multifocal femoral fractures were represented in the series. Eleven of the femoral shaft fractures were secondary to a previous, internally fixed, not yet united hip fracture (type I). Ten comminuted peritrochanteric fractures occurred in normal bone (type II). Three similar fractures were pathologic because of metastasis. Two patients had an ipsilateral fracture of the femoral shaft and the trochanteric area (type III), and one of the shaft and the femoral neck (type IV). Locking was made static in 24 cases. Additional cerclage wiring was used in three type II fractures. Five complications were as follows: one cutting out of a screw in the femoral head, two fractures of the nail, one deep venous thrombosis, and one wound hematoma. Reoperations were two salvage operations using a new nail and one evacuation of hematoma. One patient with multiple injuries and four elderly patients died within 2 months. Eighteen patients with fractures in normal bone were followed for a median of 20 (6 to 37) months. All fractures united. Two nails were removed. The end result was excellent in ten patients, good in seven, and fair in one (2-cm shortening and 20-degree external rotation). We conclude that a locked intramedullary construct with locking screws in femoral neck and distal femur controls a complex fracture situation well.

  4. Study of the Dynamic Characteristics of Ball Screw with a Load Disturbance

    Directory of Open Access Journals (Sweden)

    Zhe Du

    2016-01-01

    Full Text Available The dynamic character of ball screw is the key factor that influences the machining accuracy of numerical control (NC machine tool. To improve the dynamic characteristics of the NC machine tool, it is necessary to study the dynamic characteristics of a ball screw. In this paper, the kinematics of a ball screw mechanism (BSM are studied to expound the dynamic process of the drive, and the load disturbance is considered to analyze the contact deformation based on the Hertzian contact theory. The velocity relationships among the ball, screw, and nut are analyzed, and the influence of the contact deformation on the dynamic characteristics is simulated and investigated experimentally. The results show that the relationships between the contact deformation, which is affected by the material characteristics, the contact angle, and the load of nut are nonlinear. The contact deformation is a factor that cannot be ignored when considering the dynamic machining error of high-speed and high-precision machine tools.

  5. Kinematics and dynamics of deployable structures with scissor-like-elements based on screw theory

    Science.gov (United States)

    Sun, Yuantao; Wang, Sanmin; Mills, James K.; Zhi, Changjian

    2014-07-01

    Because the deployable structures are complex multi-loop structures and methods of derivation which lead to simpler kinematic and dynamic equations of motion are the subject of research effort, the kinematics and dynamics of deployable structures with scissor-like-elements are presented based on screw theory and the principle of virtual work respectively. According to the geometric characteristic of the deployable structure examined, the basic structural unit is the common scissor-like-element(SLE). First, a spatial deployable structure, comprised of three SLEs, is defined, and the constraint topology graph is obtained. The equations of motion are then derived based on screw theory and the geometric nature of scissor elements. Second, to develop the dynamics of the whole deployable structure, the local coordinates of the SLEs and the Jacobian matrices of the center of mass of the deployable structure are derived. Then, the equivalent forces are assembled and added in the equations of motion based on the principle of virtual work. Finally, dynamic behavior and unfolded process of the deployable structure are simulated. Its figures of velocity, acceleration and input torque are obtained based on the simulate results. Screw theory not only provides an efficient solution formulation and theory guidance for complex multi-closed loop deployable structures, but also extends the method to solve dynamics of deployable structures. As an efficient mathematical tool, the simper equations of motion are derived based on screw theory.

  6. 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.

  7. Computational fluid dynamics simulation and redesign of a screw conveyor reactor.

    Science.gov (United States)

    Wan, Yinkun; Hanley, Thomas R

    2004-01-01

    National Renewable Energy Laboratory (NREL) designed a shrinking-bed reactor to maintain a constant bulk packing density of cellulosic biomass. The high solid-to-liquid ratio in the pretreatment process allows a high sugar yield and avoids the need to flush large volumes of solution through the reactor. To scale up the shrinking-bed reactor, NREL investigated a pilot-scale screw conveyor reactor in which an interrupted flight between screws was employed to mimic the "shrinking-bed" effect. In the experiments with the screw conveyor reactor, overmixing and uneven flow occurred. These phenomena produce negative effects on biomass hydrolysis. The flow behavior inside the reactor was analyzed to allow redesign of the screw to achieve adequate mixing and even flow. In the present study, computational fluid dynamics (CFD) was utilized to simulate the fluid flow in the porous media, and a new screw design was proposed. CFD analysis performed on the redesigned reactor indicated that an even flow pattern was achieved.

  8. Walking pattern in adults with congenital hip dysplasia: 14 women examined by inverse dynamics

    DEFF Research Database (Denmark)

    Pedersen, Eva Natalia G.; Simonsen, Erik B; Alkjaer, T

    2004-01-01

    Knowledge of the gait dynamics in patients with hip dysplasia may help to understand the consequences of the mechanical changes in the hip.......Knowledge of the gait dynamics in patients with hip dysplasia may help to understand the consequences of the mechanical changes in the hip....

  9. Bone dynamic study. Evaluation for factor analysis of hip joint

    Energy Technology Data Exchange (ETDEWEB)

    Nakajima, Kotaro; Toyama, Hinako; Ishikawa, Nobuyoshi; Hatakeyama, Rokuro; Akisada, Masayoshi; Miyagawa, Shunpei

    1989-02-01

    Factor analysis was applied to dynamic study of Tc-99m MDP for the evaluation of hip joint disorders. Fifteen patients were examined; eight were normal, six was osteoarthritis in which one accompanied synovitis was included, and one was aseptic necrosis on the head of the femur. In normals, according to the Tc-99m MDP kinetics, three factor images and time-activity curves were obtained which were named as blood vessel, soft tissue, and bone factor images and curves. In the patient with osteoarthritis, increased accumulation of the hip joint was shown in bone factor image only. But in one patient, who took osteoarthritis with synovitis, marked accumulations of the Tc-99m MDP appeared not only on the bone factor image but also on the soft tissue. Operation revealed thickening synovial tissue around the hip joint, caused by inflammatory process. In follow-up studies of the patient with aseptic necrosis on the head of the left femur, exessive accumulations, which were seemed in his left hip joint on both bone and soft tissue factor images at first, were decreased respondently to the treatment of this lesion. In conclusion, the factor analysis was useful for differential diagnosis of the hip joint disorders and observation of the clinical course of the hip joint disorders.

  10. Kinematics and Dynamics Hessian Matrices of Manipulators Based on Screw Theory

    Institute of Scientific and Technical Information of China (English)

    ZHAO Tieshi; GENG Mingchao; CHEN Yuhang; LI Erwei; YANG Jiantao

    2015-01-01

    The complexity of the kinematics and dynamics of a manipulator makes it necessary to simplify the modeling process. However, the traditional representations cannot achieve this because of the absence of coordinate invariance. Therefore, the coordinate invariant method is an important research issue. First, the rigid-body acceleration, the time derivative of the twist, is proved to be a screw, and its physical meaning is explained. Based on the twist and the rigid-body acceleration, the acceleration of the end-effector is expressed as a linear-bilinear form, and the kinematics Hessian matrix of the manipulator(represented by Lie bracket) is deduced. Further, Newton-Euler’s equation is rewritten as a linear-bilinear form, from which the dynamics Hessian matrix of a rigid body is obtained. The formulae and the dynamics Hessian matrix are proved to be coordinate invariant. Referring to the principle of virtual work, the dynamics Hessian matrix of the parallel manipulator is gotten and the detailed dynamic model is derived. An index of dynamical coupling based on dynamics Hessian matrix is presented. In the end, a foldable parallel manipulator is taken as an example to validate the deduced kinematics and dynamics formulae. The screw theory based method can simplify the kinematics and dynamics of a manipulator, also the corresponding dynamics Hessian matrix can be used to evaluate the dynamical coupling of a manipulator.

  11. Kinematics and dynamics Hessian matrices of manipulators based on screw theory

    Science.gov (United States)

    Zhao, Tieshi; Geng, Mingchao; Chen, Yuhang; Li, Erwei; Yang, Jiantao

    2015-03-01

    The complexity of the kinematics and dynamics of a manipulator makes it necessary to simplify the modeling process. However, the traditional representations cannot achieve this because of the absence of coordinate invariance. Therefore, the coordinate invariant method is an important research issue. First, the rigid-body acceleration, the time derivative of the twist, is proved to be a screw, and its physical meaning is explained. Based on the twist and the rigid-body acceleration, the acceleration of the end-effector is expressed as a linear-bilinear form, and the kinematics Hessian matrix of the manipulator(represented by Lie bracket) is deduced. Further, Newton-Euler's equation is rewritten as a linear-bilinear form, from which the dynamics Hessian matrix of a rigid body is obtained. The formulae and the dynamics Hessian matrix are proved to be coordinate invariant. Referring to the principle of virtual work, the dynamics Hessian matrix of the parallel manipulator is gotten and the detailed dynamic model is derived. An index of dynamical coupling based on dynamics Hessian matrix is presented. In the end, a foldable parallel manipulator is taken as an example to validate the deduced kinematics and dynamics formulae. The screw theory based method can simplify the kinematics and dynamics of a manipulator, also the corresponding dynamics Hessian matrix can be used to evaluate the dynamical coupling of a manipulator.

  12. Computational Fluid Dynamics-Based Design Optimization Method for Archimedes Screw Blood Pumps.

    Science.gov (United States)

    Yu, Hai; Janiga, Gábor; Thévenin, Dominique

    2016-04-01

    An optimization method suitable for improving the performance of Archimedes screw axial rotary blood pumps is described in the present article. In order to achieve a more robust design and to save computational resources, this method combines the advantages of the established pump design theory with modern computer-aided, computational fluid dynamics (CFD)-based design optimization (CFD-O) relying on evolutionary algorithms and computational fluid dynamics. The main purposes of this project are to: (i) integrate pump design theory within the already existing CFD-based optimization; (ii) demonstrate that the resulting procedure is suitable for optimizing an Archimedes screw blood pump in terms of efficiency. Results obtained in this study demonstrate that the developed tool is able to meet both objectives. Finally, the resulting level of hemolysis can be numerically assessed for the optimal design, as hemolysis is an issue of overwhelming importance for blood pumps.

  13. 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.

  14. Strain energy analysis of screw dislocations in 4H-SiC by molecular dynamics

    Science.gov (United States)

    Kawamura, Takahiro; Mizutani, Mitsutoshi; Suzuki, Yasuyuki; Kangawa, Yoshihiro; Kakimoto, Koichi

    2016-03-01

    We simulated screw dislocations with the Burgers vector parallel to the [0001] direction in 4H-SiC by a classical molecular dynamics method. A stable structure of an extended dislocation generated by the dissociation of a screw dislocation was identified by calculating the strain energy caused by dislocation cores and stacking faults. As a result, we conclude that the most expected structure of the extended dislocation is made of partial dislocations with the Burgers vector b = 1/2c + 1/2c (c is equal to the thickness of one period in the c-axis direction of 4H-SiC) and the stacking fault that is parallel to the a-plane, and that the distance between the dislocation cores is less than about 44 Å.

  15. Dynamic modelling of a 3-CPU parallel robot via screw theory

    Directory of Open Access Journals (Sweden)

    L. Carbonari

    2013-04-01

    Full Text Available The article describes the dynamic modelling of I.Ca.Ro., a novel Cartesian parallel robot recently designed and prototyped by the robotics research group of the Polytechnic University of Marche. By means of screw theory and virtual work principle, a computationally efficient model has been built, with the final aim of realising advanced model based controllers. Then a dynamic analysis has been performed in order to point out possible model simplifications that could lead to a more efficient run time implementation.

  16. Comparative endurance testing of the Biomet Matthews Nail and the Dynamic Compression Screw, in simulated condylar and supracondylar femoral fractures

    Directory of Open Access Journals (Sweden)

    Davies Benjamin M

    2008-01-01

    Full Text Available Abstract Background The dynamic compression screw is a plate and screws implant used to treat fractures of the distal femur. The Biomet Matthews Nail is a new retrograde intramedullary nail designed as an alternative surgical option to treat these fractures. The objective of this study was to assess the comparative endurance of both devices. Method The dynamic compression screw (DCS and Biomet Matthews Nail (BMN were implanted into composite femurs, which were subsequently cyclically loaded using a materials testing machine. Simulated fractures were applied to each femur prior to the application of load. Either a Y type fracture or a transverse osteotomy was prepared on each composite femur using a jig to enable consistent positioning of cuts. Results The Biomet Matthews Nail demonstrated a greater endurance limit load over the dynamic compression screw in both fracture configurations. Conclusion The distal locking screws pass through the Biomet Matthews Nail in a unique "cruciate" orientation. This allows for greater purchase in the bone of the femoral condyle and potentially improves the stability of the fracture fixation. As these fractures are usually in weak osteoporotic bone, the Biomet Matthews Nail represents a favourable surgical option in these patients.

  17. Clinical Randomized Controlled Trials of Artificial Femoral Head Replacement and Dynamic Hip Screw Internal ;Fixation in Treatment of Senile Intertrochanteric Fracture%人工股骨头置换术与动力髋螺钉内固定术治疗老年转子间骨折的临床随机对照研究

    Institute of Scientific and Technical Information of China (English)

    汤岱; 李博

    2016-01-01

    目的:比较人工股骨头置换术与动力髋螺钉内固定术治疗老年转子间骨折的临床疗效,为临床选择合适的手术方式提供依据。方法选择符合标准的患者60例,按照入院先后顺序分为观察组和对照组各30例,观察组采用人工股骨头置换术,对照组采用动力髋螺钉内固定术,比较两者手术一般情况及术后髋关节恢复情况。结果两组患者伤后到手术时间差异无统计学意义(P>0.05);观察组患者手术时间、术中出血量及术后卧床时间均优于对照组,差异有统计学意义(P0.05);观察组髋关节功能优8例、良18例、中3例、差1例,优良率86.67%,对照组优3例、良17例、中4例、差6例,优良率为66.67%,差异有统计学意义( P0. 05);The operation time,intraoperative blood loss and postopera-tive bedrest time of the observation group were superior to the control group and there was significant difference in observation group compared to control group (P0. 05);The situation of hip joint function in ob-servation group was 8 excellent cases,18 good cases,3 medium cases and 1 poor case,the excellent and good rate was 86. 67%, while the control group was3,17,4,6,66. 67%respectively,the difference was statistically significant (P<0. 05). Conclusion Artificial femoral head replacement for senile in-tertrochanteric fracture has shorter operation time, less intraoperative blood loss, postoperative early weight bearing, low incidence of complications,and is beneficial to the hip joint function recovery.

  18. Atomic structure of screw dislocations intersecting the Au(111) surface: A combined scanning tunneling microscopy and molecular dynamics study

    DEFF Research Database (Denmark)

    Engbæk, Jakob; Schiøtz, Jakob; Dahl-Madsen, Bjarke;

    2006-01-01

    The atomic-scale structure of naturally occurring screw dislocations intersecting a Au(111) surface has been investigated both experimentally by scanning tunneling microscopy (STM) and theoretically using molecular dynamics (MD) simulations. The step profiles of 166 dislocations were measured usi...

  19. Hip Resurfacing. Case presentation.

    Directory of Open Access Journals (Sweden)

    Pedro Gonzalo González González

    2008-12-01

    Full Text Available Hip resurfacing in youngest patients is an excellent surgical technique for Avascular Necrosis compare with a traditional Total Hip Replacement. Report about a 21 years old female patient involved in a car accident in February 2004 with Fracture of the neck of femur treated with compression hip screw Richard’s type. Two years later the patient was diagnose with avascular necrosis of the contra lateral hip. Hip resurfacing Metal-Metal was carry out in the above mentioned patient.

  20. InterTan钉板系统与空心钉固定Pauwels Ⅲ型股骨颈骨折的有限元分析%InterTan compression hip screw versus three parallel cannulated screws for Pauwels Ⅲ femoral neck fractures: a finite element analysis

    Institute of Scientific and Technical Information of China (English)

    张晟; 王一民; 王博炜; 佟矿; 余斌

    2013-01-01

    目的 用有限元分析的方法研究InterTan钉板系统与3枚互相平行的空心钉固定PauwelsⅢ型股骨颈骨折的生物力学特点. 方法选取1名男性健康志愿者,28岁,体质量为75 kg,通过16排螺旋CT扫描,取右侧近端股骨数据作为样本.通过逆向工程软件分别重建PauwelsⅢ型股骨颈骨折三维可视化模型、InterTan钉板系统固定模型及3枚互相平行空心钉固定模型,并于Ansys软件中建立2种内固定模型的三维有限元模型,予以轴向700 N应力,研究不同内固定的von Mises应力分布和位移分布、股骨的yon Mises应力分布和位移分布,并比较内固定和股骨模型的应力峰值和位移峰值. 结果 内固定物的应力主要集中于骨折线附近,其中InterTan钉板系统钉板系统固定模型的应力峰值(65.7 MPa)低于空心钉固定模型(116.4 MPa);骨端的应力分布集中于股骨近端内侧,InterTan钉板系统固定模型的应力峰值(13.2 MPa)小于空心钉固定模型(27.6 MPa).lnterTan钉板系统固定模型中,内固定物位移方向为垂直向下,内固定物和骨端的位移峰值分别为0.84和0.76 mm;空心钉固定模型中,位移方向沿着股骨颈方向,内固定物和骨端的位移峰值分别为1.49和1.61 mm. 结论 使用InterTan钉板系统固定PauwelsⅢ型股骨颈骨折时,应力分布均匀,固定稳定性优于3枚互相平行空心钉固定.InterTan钉板系统固定时,位移方向垂直向下,髋内翻是需要预防的并发症;后者位移方向沿着股骨颈向外侧,股骨颈短缩为需要预防的并发症.%Objective To explore the biomechanical properties of InterTan compression hip screw versus versus three parallel cannulated screws in the fixation of Pauwels Ⅲ femoral neck fracture and their clinical implications.Methods A healthy male volunteer,28 years of age and 75 kg in weight,was enrolled in the present study.The spiral CT scans of his right proximal femur were used for reconstruction

  1. Theory of the lattice dynamics of model crystals containing screw dislocations

    Energy Technology Data Exchange (ETDEWEB)

    Glass, N. E.

    1976-08-01

    A theoretical study of the lattice dynamics of a simple cubic model-crystal is made. The perturbation matrix of a single screw dislocation is determined and is used with the perfect lattice Green function to find four secular equations for the frequencies altered by the dislocation. The solutions yield, depending on the model parameters, up to four separate bands of optic localized-modes across the Brillouin zone. No shifts in the perfect lattice acoustical bands are found. The frequencies of the dislocation-induced localized modes are well separated from the frequencies of the perfect lattice modes and should present no difficulty in being distinguished experimentally. The Green function of the lattice containing many parallel screw dislocations is determined by following the method in use for point defects. With this imperfect-lattice Green function, the neutron cross-section for coherent one-phonon inelastic scattering by the dislocation localized-modes is obtained. Using model parameters corresponding to simple metals, the numerical evaluation yields cross-sections on the borderline of present capabilities for experimental detection and indicates the desirability of an experimental test-search. The most important parameter is found to be the ratio of the longitudinal (lambda) to the transverse (..mu..) force constants. As lambda:..mu.. increases, the localized-mode branches separate, the many-dislocation effects become noticeable, and the cross-section for inelastic scattering by the localized-modes rises. Crystals undergoing transverse mode softening, in which lambda:..mu.. grows as ..mu.. tends toward zero, may be useful in the experimental detection of dislocation-induced lattice modes.

  2. Are allogenic or xenogenic screws and plates a reasonable alternative to alloplastic material for osteosynthesis--a histomorphological analysis in a dynamic system.

    Science.gov (United States)

    Jacobsen, C; Obwegeser, J A

    2010-12-01

    Despite invention of titanium and resorbable screws and plates, still, one of the main challenges in bone fixation is the search for an ideal osteosynthetic material. Biomechanical properties, biocompatibility, and also cost effectiveness and clinical practicability are factors for the selection of a particular material. A promising alternative seems to be screws and plates made of bone. Recently, xenogenic bone pins and screws have been invented for use in joint surgery. In this study, screws made of allogenic sheep and xenogenic human bone were analyzed in a vital and dynamic sheep-model and compared to conventional titanium screws over a standard period of bone healing of 56 days with a constant applied extrusion force. Biomechanical analysis and histomorphological evaluation were performed. After 56 days of insertion xenogenic screws made of human bone showed significantly larger distance of extrusion of on average 173.8 μm compared to allogenic screws made of sheep bone of on average 27.8 and 29.95 μm of the titanium control group. Severe resorption processes with connective tissue interposition were found in the histomorphological analysis of the xenogenic screws in contrast to new bone formation and centripetal vascularization of the allogenic bone screw, as well as in processes of incorporation of the titanium control group. The study showed allogenic cortical bone screws as a substantial alternative to titanium screws with good biomechanical properties. In contrast to other reports a different result was shown for the xenogenic bone screws. They showed insufficient holding strength with confirmative histomorphological signs of degradation and insufficient osseointegration. Before common clinical use of xenogenic osteosynthetic material, further evaluation should be performed.

  3. Effect of Dynamic Center Region on the Flow and Mixing Efficiency in a New Tri-Screw Extruder Using 3D Finite Element Modeling

    Directory of Open Access Journals (Sweden)

    X. Z. Zhu

    2013-01-01

    Full Text Available Three-dimensional finite element modeling of polymer melt flowing in a new co-rotating tri-screw extruder was established with mesh superposition technique. Based on the particle tracking technology, three typical particle trajectories in the tri-screw extruder were calculated using a 4th-order-Runge-Kutta method to study the dynamic motions of the particles. Then the flow visualizations in the local center region were carried out. Moreover, the dispersive, distributive and stretching mixing efficiencies of the tri-screw and twin-screw extruders were compared, respectively. The results show that when the particles move from one screw to another, there are great abrupt changes in the velocities and displacements, which induce the abrupt change in the stress magnitude. Most of particles, which are initially distributed in the inlet plane of the center region, fast flow out the outlet and don’t pass through any screw. This special phenomenon induces a series of new characteristics in the residence time distribution (RTD, flow number, segregation scale and time averaged efficiency. In comparison with the twin-screw extruder, the tri-screw extruder has better mixing efficiency.

  4. 股骨动力髁螺钉治疗复杂性股骨粗隆下骨折%Treatment of complicated femoral subtrochanteric fracture by dynamic condylar screw

    Institute of Scientific and Technical Information of China (English)

    汪金荣; 杨新文; 刘洪; 刘宾; 周顺文; 赵念东

    2013-01-01

    目的:总结股骨动力髁螺钉(DCS)治疗复杂性股骨粗隆下骨折的实践经验,以期提高该型骨折的治疗效果,减少并发症。方法2003年7月~2011年3月共收治股骨粗隆下复杂性骨折37例; Sein-sheimer分类:Ⅳ型28例,Ⅴ型中大粗隆相对完整9例,共37例应用DCS治疗。结果37例病人均获得术后9个月~3年的随访,满意率97.30%,2例髋关节屈曲功能与健侧相比丢失15°~25°,无髋内翻、髋外翻病例发生。 Harris评分:优33例,良2例,差2例;优良率为94.60%。结论DCS不失为复杂性股骨粗隆下骨折治疗方法的一种选择,只要技术操作得当,其治疗效果可靠,且价格低廉。%Objective To discuss the practical experience in treating complicated femoral subtrochanteric fracture by dynamic condylar screw (DCS),so as to improve the curative effect of this type fracture and to reduce complication.Methods There were 37 cases of complicated subtrochanteric fractures from the year 2003 to 2011.According to the Seinsheimer classification ,there were 28 cases of type Ⅳ,9 cases of type Ⅴ.Dynamic condylar screw fixation was conducted in all the 37 cases.Results All the 37 cases were followed up for 9 months-3 years with the satisfaction rate of being 97.30%.The flexion of hip joint lose 15°-25°in 2 cases compared with the unin-jured side.No hip varus or hip vaigus was observed .Harris scoring system showed excellent in 33 cases,good in 2 cases and poor in 2 cases,with the excellent and good rate of being 94.60%.Conclusion Dynamic condylar screw is a good treatment method for treating femoral subtrochanteric fracture .Good technical operation can achieve reliable curative effect and low cost .

  5. The Effect of Lumbar Lordosis on Screw Loosening in Dynesys Dynamic Stabilization: Four-Year Follow-Up with Computed Tomography

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    Chao-Hung Kuo

    2015-01-01

    Full Text Available Introduction. This study aimed to evaluate the effects of Dynesys dynamic stabilization (DDS on clinical and radiographic outcomes, including spinal pelvic alignment. Method. Consecutive patients who underwent 1- or 2-level DDS for lumbar spondylosis, mild degenerative spondylolisthesis, or degenerative disc disease were included. Clinical outcomes were evaluated by Visual Analogue Scale for back and leg pain, Oswestry Disability Index, and the Japanese Orthopedic Association scores. Radiographic outcomes were assessed by radiographs and computed tomography. Pelvic incidence and lumbar lordosis (LL were also compared. Results. In 206 patients with an average follow-up of 51.1 ± 20.8 months, there were 87 screws (8.2% in 42 patients (20.4% that were loose. All clinical outcomes improved at each time point after operation. Patients with loosened screws were 45 years older. Furthermore, there was a higher risk of screw loosening in DDS involving S1, and these patients were more likely to have loosened screws if the LL failed to increase after the operation. Conclusions. The DDS screw loosening rate was overall 8.2% per screw and 20.4% per patient at more than 4 years of follow-up. Older patients, S1 involvement, and those patients who failed to gain LL postoperatively were at higher risk of screw loosening.

  6. The Effect of Lumbar Lordosis on Screw Loosening in Dynesys Dynamic Stabilization: Four-Year Follow-Up with Computed Tomography.

    Science.gov (United States)

    Kuo, Chao-Hung; Chang, Peng-Yuan; Tu, Tsung-Hsi; Fay, Li-Yu; Chang, Hsuan-Kan; Wu, Jau-Ching; Huang, Wen-Cheng; Cheng, Henrich

    2015-01-01

    This study aimed to evaluate the effects of Dynesys dynamic stabilization (DDS) on clinical and radiographic outcomes, including spinal pelvic alignment. Consecutive patients who underwent 1- or 2-level DDS for lumbar spondylosis, mild degenerative spondylolisthesis, or degenerative disc disease were included. Clinical outcomes were evaluated by Visual Analogue Scale for back and leg pain, Oswestry Disability Index, and the Japanese Orthopedic Association scores. Radiographic outcomes were assessed by radiographs and computed tomography. Pelvic incidence and lumbar lordosis (LL) were also compared. In 206 patients with an average follow-up of 51.1 ± 20.8 months, there were 87 screws (8.2%) in 42 patients (20.4%) that were loose. All clinical outcomes improved at each time point after operation. Patients with loosened screws were 45 years older. Furthermore, there was a higher risk of screw loosening in DDS involving S1, and these patients were more likely to have loosened screws if the LL failed to increase after the operation. The DDS screw loosening rate was overall 8.2% per screw and 20.4% per patient at more than 4 years of follow-up. Older patients, S1 involvement, and those patients who failed to gain LL postoperatively were at higher risk of screw loosening.

  7. Leveraging gait dynamics to improve efficiency and performance of powered hip exoskeletons.

    Science.gov (United States)

    Ryder, Matthew C; Sup, Frank

    2013-06-01

    This paper presents a new mechanical design for efficient exoskeleton actuation to power the sagittal plane motion in the human hip. The device uses a DC motor to drive a Scotch-Yoke mechanism and series elasticity to take advantage of the cyclic nature of human gait and to reduce power and control requirements of the exoskeleton. The mechanism creates a transmission that varies between 4:1 and infinity and does not require the motor to reverse direction when the hip joint reverses direction. This paper provides a detailed analysis of how the dynamic nature of human walking can be leveraged with this hip exoskeleton design.

  8. An in vitro biomechanical comparison of equine proximal interphalangeal joint arthrodesis techniques: an axial positioned dynamic compression plate and two abaxial transarticular cortical screws inserted in lag fashion versus three parallel transarticular cortical screws inserted in lag fashion.

    Science.gov (United States)

    Sod, Gary A; Riggs, Laura M; Mitchell, Colin F; Hubert, Jeremy D; Martin, George S

    2010-01-01

    To compare in vitro monotonic biomechanical properties of an axial 3-hole, 4.5 mm narrow dynamic compression plate (DCP) using 5.5 mm cortical screws in conjunction with 2 abaxial transarticular 5.5 mm cortical screws inserted in lag fashion (DCP-TLS) with 3 parallel transarticular 5.5 mm cortical screws inserted in lag fashion (3-TLS) for the equine proximal interphalangeal (PIP) joint arthrodesis. Paired in vitro biomechanical testing of 2 methods of stabilizing cadaveric adult equine forelimb PIP joints. Cadaveric adult equine forelimbs (n=15 pairs). For each forelimb pair, 1 PIP joint was stabilized with an axial 3-hole narrow DCP (4.5 mm) using 5.5 mm cortical screws in conjunction with 2 abaxial transarticular 5.5 mm cortical screws inserted in lag fashion and 1 with 3 parallel transarticular 5.5 mm cortical screws inserted in lag fashion. Five matching pairs of constructs were tested in single cycle to failure under axial compression, 5 construct pairs were tested for cyclic fatigue under axial compression, and 5 construct pairs were tested in single cycle to failure under torsional loading. Mean values for each fixation method were compared using a paired t-test within each group with statistical significance set at P<.05. Mean yield load, yield stiffness, and failure load under axial compression and torsion, single cycle to failure, of the DCP-TLS fixation were significantly greater than those of the 3-TLS fixation. Mean cycles to failure in axial compression of the DCP-TLS fixation was significantly greater than that of the 3-TLS fixation. The DCP-TLS was superior to the 3-TLS in resisting the static overload forces and in resisting cyclic fatigue. The results of this in vitro study may provide information to aid in the selection of a treatment modality for arthrodesis of the equine PIP joint.

  9. Dynamic long leg casting fixation for treating 12- to 18-month-old infants with developmental dysplasia of the hip.

    Science.gov (United States)

    Cai, Zhencun; Li, Lianyong; Zhang, Lijun; Ji, Shijun; Zhao, Qun

    2017-02-01

    Objective To evaluate the effect of dynamic long leg casting in paediatric patients with developmental dysplasia of hip (DDH) diagnosed at 12-18 months. Methods The adductor tenotomy, closed reduction, and dynamic long leg casting method was adopted to treat paediatric patients with DDH. The hips were divided into four groups according to the Tonnis radiographic dislocation classification. Groups were also classified according to the baseline acetabular index (AI): 30°-35°, 36°-40°, and > 40°. The outcomes of the reductions were evaluated according to McKay's hip function criteria and Severin's radiological criteria. Results A total of 246 patients (339 hips) had complete follow-up data. After 3 months of orthosis fixation, the results were satisfactory in 264 hips (77.88%). Hip function was rated as 'excellent' or 'good' in 43 of 51 (84.31%) Tonnis type 1 hips, 125 of 155 (80.65%) type 2 hips, 70 of 90 (77.78%) type 3 hips, and 34 of 43 (79.07%) type 4 hips. The higher the baseline AI, the lower the rates of 'excellent' and 'good' hip function. Favourable radiological results (Severin types I and II) were found in 266 of 339 (78.47) hips. Conclusions Dynamic long leg casting is an effective method for treating patients with DDH aged 12-18 months at diagnosis.

  10. Computer-assisted navigation systems for insertion of cannulated screws in femoral neck fractures: a comparison of bi-planar robot navigation with optoelectronic navigation in a Synbone hip model trial

    Institute of Scientific and Technical Information of China (English)

    WANG Jun-qiang; ZHAO Chun-peng; SU Yong-gang; ZHOU Li; HU Lei; WANG Tian-miao; WANG Man-yi

    2011-01-01

    Background Computer-assisted procedures have recently been introduced for navigated femoral neck screw placement.Currently there is little information available regarding accuracy and efficiency of the different navigated procedures.The aim of this study was to compare two fluoroscopic navigation tracking technologies,a novel bi-planar robot navigation and standardized optoelectronic navigation,versus standard freehand fluoroscopic insertion in a Synbone hip model.Methods Eighteen fixed Synbone hip models were divided into 3 groups.C-arm navigated cannulated screws (AO-ASIF,diameter 7.3 mm) were inserted using freehand targeting (control group).A novel bi-planar robot system (TINAV,GD2000) and an optoelectronic system (Stryker OTS Navigation System) were used for the navigated procedures (robot group and optoelectronic group).Accuracy was measured using radiographic evaluation including the measurement of screw parallelism and decentralization,and joint penetration.To evaluate the efficiency,the number of guidewire passes,operative time and fluoroscopic images taken were noted.Results The two computer-assisted systems provided significantly improved accuracy compared to the freehand technique.Each of the parameters,including guidewire passes and number of fluoroscopy images,was significantly lower when using the computer-assisted systems than for freehand-unguided insertion (P <0.05),but operative time was significantly shorter when using freehand-unguided insertion than for the computer-assisted systems (P <0.05).Accuracy,operative time and number of fluoroscopy images taken were similar among the two navigated groups (P >0.05),but guidewire passes in the robot group were significantly less than in the optoelectronic group (P <0.05).Conclusions Both bi-planar robot navigation and optoelectronic navigation were similarly accurate and have the potential to improve accuracy and reduce radiation for freehand fluoroscopic targeting for insertion of cannulated

  11. Hip actuations can be used to control bifurcations and chaos in a passive dynamic walking model.

    Science.gov (United States)

    Kurz, Max J; Stergiou, Nicholas

    2007-04-01

    We explored how hip joint actuation can be used to control locomotive bifurcations and chaos in a passive dynamic walking model that negotiated a slightly sloped surface (gammapassive dynamic walking model was capable of producing a chaotic locomotive pattern when the ramp angle was 0.01839 radhip actuation resulted in rapid transition to any locomotive pattern available in the chaotic attractor and induced stability at ramp angles that were previously considered unstable. Our results detail how chaos can be used as a control scheme for locomotion.

  12. Finite element analysis of sliding distance and contact mechanics of hip implant under dynamic walking conditions.

    Science.gov (United States)

    Gao, Yongchang; Jin, Zhongmin; Wang, Ling; Wang, Manyi

    2015-06-01

    An explicit finite element method was developed to predict the dynamic behavior of the contact mechanics for a hip implant under normal walking conditions. Two key parameters of mesh sensitivity and time steps were examined to balance the accuracy and computational cost. Both the maximum contact pressure and accumulated sliding distance showed good agreement with those in the previous studies using the implicit finite element analysis and analytical methods. Therefore, the explicit finite element method could be used to predict the contact pressure and accumulated sliding distance for an artificial hip joint simultaneously in dynamic manner.

  13. Association between hip abductor function, rear-foot dynamic alignment, and dynamic knee valgus during single-leg squats and drop landings

    Directory of Open Access Journals (Sweden)

    Yoshinori Kagaya

    2015-06-01

    Conclusion: Dynamic hip mal-alignment might be associated with both greater KID and HOD, whereas rear-foot eversion is associated only with greater KID. Hip abductor and rear-foot dysfunction are important factors for dynamic knee valgus and thus evaluating DTT and HFT will help to prevent dynamic knee valgus.

  14. A Technique for Removal of Forearm Dynamic Compression Plate with Stripped Screws: A Report of Three Cases

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    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.

  15. Effect of Stiffness of Rolling Joints on the Dynamic Characteristic of Ball Screw Feed Systems in a Milling Machine

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    Dazhong Wang

    2015-01-01

    Full Text Available Dynamic characteristic of ball screw feed system in a milling machine is studied numerically in this work. In order to avoid the difficulty in determining the stiffness of rolling joints theoretically, a dynamic modeling method for analyzing the feed system is discussed, and a stiffness calculation method of the rolling joints is proposed based on the Hertz contact theory. Taking a 3-axis computer numerical control (CNC milling machine set ermined as a research object, the stiffness of its fixed joint between the column and the body together with the stiffness parameters of the rolling joints is evaluated according to the Takashi Yoshimura method. Then, a finite element (FE model is established for the machine tool. The correctness of the FE model and the stiffness calculation method of the rolling joints are validated by theoretical and experimental modal analysis results of the machine tool’s workbench. Under the two modeling methods of joints incorporating the stiffness parameters and rigid connection, a theoretical modal analysis is conducted for the CNC milling machine. The natural frequencies and modal shapes reveal that the joints’ dynamic characteristic has an important influence on the dynamic performance of a whole machine tool, especially for the case with natural frequency and higher modes.

  16. An evidence-based review of hip-focused neuromuscular exercise interventions to address dynamic lower extremity valgus

    Directory of Open Access Journals (Sweden)

    Ford KR

    2015-08-01

    Full Text Available Kevin R Ford,1 Anh-Dung Nguyen,2 Steven L Dischiavi,1 Eric J Hegedus,1 Emma F Zuk,2 Jeffrey B Taylor11Department of Physical Therapy, High Point University, High Point, NC, USA; 2Department of Athletic Training, School of Health Sciences, High Point University, High Point, NC, USAAbstract: Deficits in proximal hip strength or neuromuscular control may lead to dynamic lower extremity valgus. Measures of dynamic lower extremity valgus have been previously shown to relate to increased risk of several knee pathologies, specifically anterior cruciate ligament ruptures and patellofemoral pain. Therefore, hip-focused interventions have gained considerable attention and been successful in addressing these knee pathologies. The purpose of the review was to identify and discuss hip-focused exercise interventions that aim to address dynamic lower extremity valgus. Previous electromyography, kinematics, and kinetics research support the use of targeted hip exercises with non-weight-bearing, controlled weight-bearing, functional exercise, and, to a lesser extent, dynamic exercises in reducing dynamic lower extremity valgus. Further studies should be developed to identify and understand the mechanistic relationship between optimized biomechanics during sports and hip-focused neuromuscular exercise interventions.Keywords: dynamic lower extremity valgus, hip neuromuscular control, ACL injury rehabilitation, patellofemoral pain, hip muscular activation

  17. In vivo measurement of human knee and hip dynamics using MIMO system identification.

    Science.gov (United States)

    Koopman, B; van Asseldonk, E F; van der Kooij, H

    2010-01-01

    This study presents a new method for the estimation of the dynamic impedance of multi-joint leg movements. The method is based on Multi Input Multi Output (MIMO) system identification techniques and is designed for continuous torque perturbations at the hip and knee joint. Preliminary results from this study indicate that MIMO system identification can successfully be used to estimate the hip and knee impedance and the interaction dynamics between both joints. It is also concluded that, in order to create a good model representation of the leg impedance, the effect of biarticular muscles needs to be taken into account. The obtained measures for joint impedance might be used for clinical assessment and follow up of patients, as well as for the development of supportive devices.

  18. Posterior dislocation of hip with ipsilateral intertrochanteric fracture: A report of two cases

    Directory of Open Access Journals (Sweden)

    Rehan Ul Haq

    2016-01-01

    Full Text Available Posterior dislocations of the hip are known to be associated with fractures of the femoral head, neck, shaft, or posterior acetabular wall. However, its association with ipsilateral intertrochanteric fracture has only been anecdotally described in the English literature. We report two such cases managed by open reduction (OR of the hip and internal fixation (IF of the intertrochanteric fracture. The first case was a 26-year-old male who was managed by OR of the hip with IF of the intertrochanteric fracture with a dynamic hip screw and had a good functional result at 1-year followup. The second case was a 36-year-old female who was also managed by OR of the hip with IF of the head fragments with Herbert screw and IF of the intertrochanteric fracture with a dynamic condylar screw. The patient had a fair, functional result at 1-year followup. With the increase in high energy trauma, these fracture patterns have become more common, and there is an urgent need to review the existing classifications so that these fractures are better categorized, and treatment guidelines defined.

  19. Posterior dislocation of hip with ipsilateral intertrochanteric fracture: A report of two cases

    Science.gov (United States)

    Ul Haq, Rehan; Kumar, Jaswant; Dhammi, IK; Jain, Anil K

    2016-01-01

    Posterior dislocations of the hip are known to be associated with fractures of the femoral head, neck, shaft, or posterior acetabular wall. However, its association with ipsilateral intertrochanteric fracture has only been anecdotally described in the English literature. We report two such cases managed by open reduction (OR) of the hip and internal fixation (IF) of the intertrochanteric fracture. The first case was a 26-year-old male who was managed by OR of the hip with IF of the intertrochanteric fracture with a dynamic hip screw and had a good functional result at 1-year followup. The second case was a 36-year-old female who was also managed by OR of the hip with IF of the head fragments with Herbert screw and IF of the intertrochanteric fracture with a dynamic condylar screw. The patient had a fair, functional result at 1-year followup. With the increase in high energy trauma, these fracture patterns have become more common, and there is an urgent need to review the existing classifications so that these fractures are better categorized, and treatment guidelines defined. PMID:27746503

  20. Coupling of dynamics and contact mechanics of artificial hip joints in a pendulum model.

    Science.gov (United States)

    Liu, H; Ellison, P J; Xu, H; Jin, Z

    2010-01-01

    To date, fully coupled dynamics and contact mechanics analysis is still limited by expensive computational cost and long computing time and has not been addressed comprehensively, particularly in the hip joint. To understand the influence of different parameters on the biomechanics of the total hip replacement (THR) and improve its design, two numerical approaches were developed and implemented in finite element models to investigate the coupling between the dynamics response and the contact mechanics for three different THR configurations, metal-on-polyethylene (MOP), metal-on-metal (MOM), and ceramic-on-ceramic (COC). The dynamic force and the contact pressure distribution at the bearing surfaces from the two methods were predicted and compared. The influences of various parameters (motion angle, load applied in the pendulum, friction coefficient, geometry, and material properties) were subsequently investigated. From the comparisons, the decoupled method, based on the rigid-body dynamics and the quasi-static elastic contact mechanics, was adequate to predict the performance of the THRs efficiently. The load had the greatest influence on the dynamics/contact mechanics among other factors.

  1. 全髋关节置换与空心螺钉置入内固定修复中老年股骨颈骨折:髋关节功能比较%Total hip arthroplasty versus hollow screw fixation for the repair of femoral neck fractures in the middle-aged and elder patients:hip function

    Institute of Scientific and Technical Information of China (English)

    林庆波

    2015-01-01

    BACKGROUND:The repair method of femoral neck fractures included internal fixation and hip arthroplasty. The selection of repair methods is affected by many factors, such as age, condition of patients, and own physical condition. The selection of repair methods for femoral neck fractures is always controversial. OBJECTIVE:To compare the hip function and prognosis of elderly patients with femoral neck fractures after total hip arthroplasty and hol ow screw fixation. METHODS:140 patients aged less than 60 years, who accepted treatment in Rizhao Hospital of Traditional Chinese Medicine from April 2012 to February 2014, were selected. They were randomly divided into replacement group and fixation group (n=70). Patients in the replacement group received total hip arthroplasty, and patients in the fixation group received hol ow compression screw fixation. Harris score of the hip, complications and satisfactions of the hip were observed, compared and analyzed between the two groups at 1 month post surgery. RESULTS AND CONCLUSION:The excel ent and good rate of Harris score at 1 month post surgery was significantly higher in the replacement group (90%) than in the fixation group (63%) (P  目的:对比中老年股骨颈骨折患者行全髋关节置换与空心螺钉置入内固定治疗后的髋关节功能及预后。  方法:选取2012年4月至2014年2月日照市中医医院收治的140例股骨颈骨折患者,年龄小于60岁,随机分为置换组和内固定组,每组70例。置换组采用全髋关节置换治疗,内固定组患者采取空心加压螺钉置入内固定治疗。观察两组患者治疗后1个月的髋关节功能Harris评分、并发症发生情况及关节功能满意度,并进行对比分析。  结果与结论:治疗后1个月,置换组Harris评分的优良率为90%,明显高于内固定组63%,差异有显著性意义(P<0.05);置换组并发症发生率为6%,明显低于内固定组29%

  2. Acute effect of static and dynamic stretching on hip dynamic range of motion during instep kicking in professional soccer players.

    Science.gov (United States)

    Amiri-Khorasani, Mohammadtaghi; Abu Osman, Noor A; Yusof, Ashril

    2011-06-01

    The purpose of this study was to examine the effects of static and dynamic stretching within a pre-exercise warm-up on hip dynamic range of motion (DROM) during instep kicking in professional soccer players. The kicking motions of dominant legs were captured from 18 professional adult male soccer players (height: 180.38 ± 7.34 cm; mass: 69.77 ± 9.73 kg; age: 19.22 ± 1.83 years) using 4 3-dimensional digital video cameras at 50 Hz. Hip DROM at backward, forward, and follow-through phases (instep kick phases) after different warm-up protocols consisting of static, dynamic, and no-stretching on 3 nonconsecutive test days were captured for analysis. During the backswing phase, there was no difference in DROM after the dynamic stretching compared with the static stretching relative to the no-stretching method. There was a significant difference in DROM after the dynamic stretching compared with the static stretching relative to the no-stretching method during (a) the forward phase with p after dynamic stretching incorporated in warm-ups, hence increasing the chances of scoring and injury prevention during soccer games.

  3. The Effects of Dynamic Range of Motion Exercises and Static Stretching on Strength and Range of Motion of the Hip Joint.

    Science.gov (United States)

    Kanetzke, Carol A.

    The effects of Dynamic Range of Motion (D'ROM) exercises and static stretch on hip flexibility and hip strength were examined. One hundred one male and female college students were divided into three groups: D'ROM, static stretch (ST), and control (C). All subjects were measured before and after treatment for hip flexibility and strength. Two…

  4. Assessment of Diagnostic Value of Single View Dynamic Technique in Diagnosis of Developmental Dysplasia of Hip: A Comparison with Static and Dynamic Ultrasond Techniques.

    Science.gov (United States)

    Alamdaran, Seyed Ali; Kazemi, Sahar; Parsa, Ali; Moghadam, Mohammad Hallaj; Feyzi, Ali; Mardani, Reza

    2016-10-01

    Developmental dysplasia of hip (DDH) is a common childhood disorder, and ultrasonography examination is routinely used for screening purposes. In this study, we aimed to evaluate a modified combined static and dynamic ultrasound technique for the detection of DDH and to compare with the results of static and dynamic ultrasound techniques. In this cross-sectional study, during 2013- 2015, 300 high-risk infants were evaluated by ultrasound for DDH. Both hips were examined with three techniques: static, dynamic and single view static and dynamic technique. Statistical analysis was performed using SPSS version 11.5. Patients aged 9 days to 83 weeks. 75% of the patients were 1 to 3 months old. Among 600 hip joints, about 5% were immature in static sonography and almost all of them were unstable in dynamic techniques. 0.3% of morphologically normal hips were unstable in dynamic sonography and 9% of unstable hips had normal morphology. The mean β angle differences in coronal view before and after stress maneuver was 14.43±5.47° in unstable hips. Single view static and dynamic technique revealed that all cases with acetabular dysplasia, instability and dislocation, except two dislocations, were detected by dynamic transverse view. For two cases, Ortolani maneuver showed femoral head reversibility in dislocated hips. Using single view static and dynamic technique was indicative and applicable for detection of more than 99% of cases. Single view static and dynamic technique not only is a fast and easy technique, but also it is of high diagnostic value in assessment of DDH.

  5. 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

  6. Dynamic analysis of the mechanical seals of the rotor of the labyrinth screw pump

    Science.gov (United States)

    Lebedev, A. Y.; Andrenko, P. M.; Grigoriev, A. L.

    2017-08-01

    A mathematical model of the work of the mechanical seal with smooth rings made from cast tungsten carbide in the condition of liquid friction is drawn up. A special feature of this model is the allowance for the thermal expansion of a liquid in the gap between the rings; this effect acting in the conjunction with the frictional forces creates additional pressure and lift which in its turn depends on the width of the gap and the speed of sliding. The developed model displays the processes of separation, transportation and heat removal in the compaction elements and also the resistance to axial movement of the ring arising in the gap caused by the pumping effect and the friction in the flowing liquid; the inertia of this fluid is taken into account by the mass reduction method. The linearization of the model is performed and the dynamic characteristics of the transient processes and the forced oscillations of the device are obtained. The conditions imposed on the parameters of the mechanical seal are formulated to provide a regime of the liquid friction, which minimizes the wear.

  7. A Novel Approach for Dynamic Testing of Total Hip Dislocation under Physiological Conditions.

    Science.gov (United States)

    Herrmann, Sven; Kluess, Daniel; Kaehler, Michael; Grawe, Robert; Rachholz, Roman; Souffrant, Robert; Zierath, János; Bader, Rainer; Woernle, Christoph

    2015-01-01

    Constant high rates of dislocation-related complications of total hip replacements (THRs) show that contributing factors like implant position and design, soft tissue condition and dynamics of physiological motions have not yet been fully understood. As in vivo measurements of excessive motions are not possible due to ethical objections, a comprehensive approach is proposed which is capable of testing THR stability under dynamic, reproducible and physiological conditions. The approach is based on a hardware-in-the-loop (HiL) simulation where a robotic physical setup interacts with a computational musculoskeletal model based on inverse dynamics. A major objective of this work was the validation of the HiL test system against in vivo data derived from patients with instrumented THRs. Moreover, the impact of certain test conditions, such as joint lubrication, implant position, load level in terms of body mass and removal of muscle structures, was evaluated within several HiL simulations. The outcomes for a normal sitting down and standing up maneuver revealed good agreement in trend and magnitude compared with in vivo measured hip joint forces. For a deep maneuver with femoral adduction, lubrication was shown to cause less friction torques than under dry conditions. Similarly, it could be demonstrated that less cup anteversion and inclination lead to earlier impingement in flexion motion including pelvic tilt for selected combinations of cup and stem positions. Reducing body mass did not influence impingement-free range of motion and dislocation behavior; however, higher resisting torques were observed under higher loads. Muscle removal emulating a posterior surgical approach indicated alterations in THR loading and the instability process in contrast to a reference case with intact musculature. Based on the presented data, it can be concluded that the HiL test system is able to reproduce comparable joint dynamics as present in THR patients.

  8. A Novel Approach for Dynamic Testing of Total Hip Dislocation under Physiological Conditions.

    Directory of Open Access Journals (Sweden)

    Sven Herrmann

    Full Text Available Constant high rates of dislocation-related complications of total hip replacements (THRs show that contributing factors like implant position and design, soft tissue condition and dynamics of physiological motions have not yet been fully understood. As in vivo measurements of excessive motions are not possible due to ethical objections, a comprehensive approach is proposed which is capable of testing THR stability under dynamic, reproducible and physiological conditions. The approach is based on a hardware-in-the-loop (HiL simulation where a robotic physical setup interacts with a computational musculoskeletal model based on inverse dynamics. A major objective of this work was the validation of the HiL test system against in vivo data derived from patients with instrumented THRs. Moreover, the impact of certain test conditions, such as joint lubrication, implant position, load level in terms of body mass and removal of muscle structures, was evaluated within several HiL simulations. The outcomes for a normal sitting down and standing up maneuver revealed good agreement in trend and magnitude compared with in vivo measured hip joint forces. For a deep maneuver with femoral adduction, lubrication was shown to cause less friction torques than under dry conditions. Similarly, it could be demonstrated that less cup anteversion and inclination lead to earlier impingement in flexion motion including pelvic tilt for selected combinations of cup and stem positions. Reducing body mass did not influence impingement-free range of motion and dislocation behavior; however, higher resisting torques were observed under higher loads. Muscle removal emulating a posterior surgical approach indicated alterations in THR loading and the instability process in contrast to a reference case with intact musculature. Based on the presented data, it can be concluded that the HiL test system is able to reproduce comparable joint dynamics as present in THR patients.

  9. Postoperative radiographs following hip fracture surgery. Do they influence patient management?

    Science.gov (United States)

    Chakravarthy, J; Mangat, K; Qureshi, A; Porter, K

    2007-03-01

    There is still much debate on the appropriateness of taking postoperative radiographs following hip fracture surgery. In our unit, it is routine practice to request postoperative radiographs after hip hemiarthroplasty but not after internal fixation. An audit conducted in our unit highlighted the low acute implant-related complications. This prompted us to conduct a national audit on current UK practice regarding the use of check radiographs following hip fracture surgery. Retrospective case note review of all patients undergoing hip fracture surgery at our hospital, from 2002 to 2004, was performed. Patients undergoing revision surgery in the same admission were identified to determine whether check radiograph influenced the decision. Subsequently a postal performa was sent to 450 randomly chosen UK Orthopaedic Consultants. The performa was designed to determine practice relating to postoperative radiographs. It also attempted to determine whether postoperative radiographs (when requested) influenced the subsequent clinical management of the patient. A total of 1265 hip fractures treated surgically were reviewed locally. Average length of stay was 29.5 days. There were five acute implant-related complications. One revision was performed for a long hip screw which was obvious on the intra-operative image intensifier films. Only one decision to revise (because of incongruous reduction of a hip hemiarthroplasty) was based on a problem identified on a routine check radiograph. All patients undergoing revision were clinically symptomatic. We received 300 responses. Ninety-six per cent routinely took postoperative radiographs following hip hemiarthroplasty of which 83% allowed the patient to mobilise before checking the radiograph. Following dynamic hip screw (DHS)/dynamic condylar screw (DCS) fixation, 61% took check radiographs of which 75% allowed the patient to mobilise prior to reviewing the radiograph. Following cannulated screw (CS) fixation, 58% routinely

  10. Hip motion analysis using multi phase (virtual and physical) simulation of the patient-specific hip joint dynamics.

    Science.gov (United States)

    Otake, Yoshito; Suzuki, Naoki; Hattori, Asaki; Miki, Hidenobu; Yamamura, Mitsuyoshi; Yonenobu, Kazuo; Ochi, Takahiro; Sugano, Nobuhiko

    2008-01-01

    In total hip arthroplasty (THA), the patient-specific bone geometry or the characteristics of the skeletal movement should be considered during treatment in order to prevent complications. In this paper, we propose a novel approach for the analysis of joints which combines the patient-specific virtual and physical simulation. The patient-specific anatomical structure and hip motion was obtained from CT and optical motion capture. The virtual simulation was conducted by integrating these data using virtual reality technique. The physical simulation was achieved by using plaster models of the patient's pelvis and femur and robotic manipulator. The plaster models were driven by two robotic manipulators to reproduce the hip motion. The accuracy of the robot movement was 0.245 mm over the working area according to the validation by an optical tracking system. By combining this system with linear actuators that reproduce the muscle functions, patient-specific muscle function can be simulated, thereby helping clinicians to diagnose and make a treatment plan.

  11. INTERTAN髓内钉与滑动髋螺钉治疗老年性粗隆间和粗隆下骨折的临床效果比较%Clinical efficacy comparison of INTERTAN intramuscular nail and sliding hip screw in treatment of elderly intertrochanteric and subtrochanteric fractures

    Institute of Scientific and Technical Information of China (English)

    李雄辉; 钟涌; 刘阳灿

    2015-01-01

    Objective To study the clinical efficacy of INTERTAN intramuscular nail and sliding hip screw in treat-ment of elderly intertrochanteric and subtrochanteric fractures. Methods 80 patients with elderly intertrochanteric and subtrochanteric fractures treated in our hospital from January 2012 to January 2014 were selected,and were randomly divided into intramuscular nail group (40 cases) and hip screw group (40 cases).The bleeding volume,postoperative drainage volume,operation time of two groups was compared;visual analogue scale (VAS) after 3 and 6 months was sta-tistically analyzed. Results The operation time of two groups had no significant difference (P>0.05).The bleeding vol-ume,postoperative drainage volume in intramuscular nail group was less than that in hip screw group,the difference was significance (P0.05). Conclusion The efficacy of intramuscular nail in treatment of elderly intertrochanteric and subtrochanteric fractures is better than that of hip screw,the recovery and postoperative complications in two ways has no obvious difference.%目的:研究INTERTAN髓内钉与滑动髋螺钉(DHS)治疗老年性粗隆间和粗隆下骨折的效果。方法选取2012年1月~2014年1月在本院进行治疗的老年粗隆间和粗隆下骨折患者80例,按照随机数字表法分为髓内钉组40例和髋螺钉组40例。比较两组患者的术中出血量、术后引流量、手术时间等,术后3、6个月分别进行视觉模拟评分(VAS)。结果两组手术时间差异无统计学意义(P>0.05);髓内钉组术中出血量和术后引流量明显少于髋螺钉组,差异有统计学意义(P0.05)。结论髓内钉与髋螺钉治疗老年性粗隆间和粗隆下骨折,髓内钉方式优于髋螺钉方式,在术后恢复、并发症方面两种方式并无明显差异。

  12. Unilateral static and dynamic hamstrings stretching increases contralateral hip flexion range of motion.

    Science.gov (United States)

    Chaouachi, Anis; Padulo, Johnny; Kasmi, Sofien; Othmen, Aymen Ben; Chatra, Moktar; Behm, David G

    2017-01-01

    Static (SS) and dynamic stretching (DS) can lead to subsequent performance impairments or enhancement with the stretched limb. Crossover or non-local muscle fatigue (NLMF) refers to unilateral fatigue-induced impairments in a contralateral or non-exercised muscle. Whereas there are conflicting findings in the NLMF literature, there are few studies examining the effect of an acute bout of SS or DS on contralateral flexibility, torque or power. Fourteen highly trained subjects (means ± standard deviations: 18 ± 2 years; 179·4 ± 4·6 cm; 70·5 ± 6·3 kg; %body fat: 10·7 ± 2·5%) were tested before and following separate sessions of eight repetitions of 30 s of unilateral hip flexion SS or DS. Pre- and postintervention testing at 1 and 10 min included hip flexor range of motion (ROM), isokinetic leg flexion torque and power at 60°.s(-1) and 300°.s(-1) of the stretched and contralateral limbs. The stretched limb had a 6·3% (P = 0·01; ES: 0·91) ROM increase with DS at 10 min. The contralateral non-stretched hip flexors experienced ROM increases with SS of 5·7% (P = 0·02; ES: 0·68) from pretest to 1 min post-test, whereas DS showed 7·1% (P<0·0001; ES: 1·09) and 8·4% (P = 0·005; ES: 0·89) increases, respectively. There were no relative differences in ROM changes between conditions or limbs nor any stretch-induced changes in isokinetic torque or power. In conclusion, unilateral SS and DS augment contralateral limb ROM likely through an increased stretch tolerance.

  13. Experimental determination of the dynamic properties of screw compressors; Die experimentelle Bestimmung der dynamischen Eigenschaften von Schraubenkompressoren

    Energy Technology Data Exchange (ETDEWEB)

    Rinder, L. [Technische Univ., Wien (Austria). Abt. Maschinenelemente; Svigler, J.; Pasek, M.; Albl, P. [Westboehmische Univ., Pilsen (Czech Republic). Lehrstuhl fuer Mechanik

    1998-12-31

    The demand for continuing improvements of screw machines leads to a vibration research of these machines. The presented paper deals with the experimental measurement of screw compressor operational vibrations and the determination of vibration sources. The measuring of operational vibrations, modal analysis and the determination of mode shape forms of a screw compressor were performed. The main sources of the operational vibrations were determined and the screw compressor eigenfrequencies were found in the frequency spectrum. This contribution forms a basis for the comparison of the theoretical and experimental results. This work was done in cooperation between the University of West Bohemia Pilsen and the Technical University Vienna. (orig.) [Deutsch] Staendig steigende Anforderungen an die Laufruhe von Schraubenkompressoren machen Schwingungsuntersuchungen an diesen Maschinen notwendig. Die vorliegende Arbeit beschreibt Messungen des Betriebs-Schwingungszustandes und die Bestimmung der Erregerquellen an einem oeleingespritzten Schraubenverdichter. Es wird der Schwingungszustand mit Beschleunigungsaufnehmern gemessen, eine Modalanalyse beider Rotoren durchgefuehrt und es werden die Eigenformen der Laeufer bestimmt. Die Haupterregerquellen fuer die Schwingungen koennen ermittelt werden. Die Eigenfrequenzen des Kompressors sind im Frequenzspektrum festzustellen. Die Ergebnisse dienen als Basis fuer den Vergleich zwischen experimenteller Schwingungsanalyse und theoretischen Schwingungsuntersuchungen. Ueber theoretische Ergebnisse soll in naechster Zukunft berichtet werden. Die Arbeit entstand im Rahmen einer Zusammenarbeit zwischen der Westboehmischen Universitaet Pilsen und der Technischen Universitaet Wien. Die Schwingungsmessungen wurden am Schraubenverdichterpruefstand des Instituts fuer Maschinenelemente der TU Wien durchgefuehrt. (orig.)

  14. Hard-on-hard lubrication in the artificial hip under dynamic loading conditions.

    Directory of Open Access Journals (Sweden)

    Robert Sonntag

    Full Text Available The tribological performance of an artificial hip joint has a particularly strong influence on its success. The principle causes for failure are adverse short- and long-term reactions to wear debris and high frictional torque in the case of poor lubrication that may cause loosening of the implant. Therefore, using experimental and theoretical approaches models have been developed to evaluate lubrication under standardized conditions. A steady-state numerical model has been extended with dynamic experimental data for hard-on-hard bearings used in total hip replacements to verify the tribological relevance of the ISO 14242-1 gait cycle in comparison to experimental data from the Orthoload database and instrumented gait analysis for three additional loading conditions: normal walking, climbing stairs and descending stairs. Ceramic-on-ceramic bearing partners show superior lubrication potential compared to hard-on-hard bearings that work with at least one articulating metal component. Lubrication regimes during the investigated activities are shown to strongly depend on the kinematics and loading conditions. The outcome from the ISO gait is not fully confirmed by the normal walking data and more challenging conditions show evidence of inferior lubrication. These findings may help to explain the differences between the in vitro predictions using the ISO gait cycle and the clinical outcome of some hard-on-hard bearings, e.g., using metal-on-metal.

  15. Hard-on-hard lubrication in the artificial hip under dynamic loading conditions.

    Science.gov (United States)

    Sonntag, Robert; Reinders, Jörn; Rieger, Johannes S; Heitzmann, Daniel W W; Kretzer, J Philippe

    2013-01-01

    The tribological performance of an artificial hip joint has a particularly strong influence on its success. The principle causes for failure are adverse short- and long-term reactions to wear debris and high frictional torque in the case of poor lubrication that may cause loosening of the implant. Therefore, using experimental and theoretical approaches models have been developed to evaluate lubrication under standardized conditions. A steady-state numerical model has been extended with dynamic experimental data for hard-on-hard bearings used in total hip replacements to verify the tribological relevance of the ISO 14242-1 gait cycle in comparison to experimental data from the Orthoload database and instrumented gait analysis for three additional loading conditions: normal walking, climbing stairs and descending stairs. Ceramic-on-ceramic bearing partners show superior lubrication potential compared to hard-on-hard bearings that work with at least one articulating metal component. Lubrication regimes during the investigated activities are shown to strongly depend on the kinematics and loading conditions. The outcome from the ISO gait is not fully confirmed by the normal walking data and more challenging conditions show evidence of inferior lubrication. These findings may help to explain the differences between the in vitro predictions using the ISO gait cycle and the clinical outcome of some hard-on-hard bearings, e.g., using metal-on-metal.

  16. Biomechanical comparison of dynamic condylar screw and locking compression plate fixation in unstable distal femoral fractures: An in vitro study

    Directory of Open Access Journals (Sweden)

    Ashutosh Kumar Singh

    2013-01-01

    Full Text Available Background: Distal femur fractures are difficult to manage and the selection of implant for internal fixation remains controversial. The objective of this study is to establish the relative strength of fixation of a distal femoral locking plate (DFLP compared with the dynamic condylar screw (DCS in the distal femur fractures. Materials and Methods: Study was conducted on 16 freshly harvested cadaveric distal femoral specimens, eight implanted with DCS and other eight with DFLP. The construct was made unstable by removing a standard sized medial wedge of 1 cm base (gap-osteotomy beginning 6 cm proximal to the lateral joint line in distal metaphyseal region with the loss of medial buttress. Fatigue test was conducted under load control mode at the frequency of I Hz. Specimens were subjected to cyclic loading of 2 kN, under observation for 50,000 cycles or until failure/cutout, which ever occurred earlier. Results: In DFLP group, there was no implant failure and the average number of cycles sustained was 50,000. Six out of eight specimens completed 50,000 cycles and two failed in DCS group. The average number of cycles sustained by DCS was 46150. Though the bone quality as assessed by dual energy X-ray absorptiometry DEXA was comparable in both DFLP and DCS group ( P = 0.06, none failed in DFLP group and subsidence was 1.02 ± 0.34 mm (range: 0.60-1.32 mm, which was significantly 43% lower ( P = 0.006 than subsidence in DCS group (1.82 ± 0.58; range: 1.20-3.08 mm. The average stiffness of DCS group was 52.8 ± 4.2 N/mm, which was significantly lower than average stiffness of locked condylar plate group (71.2 ± 5.1 N/mm ( P = 0.02. Conclusions: DFLP fixation of the distal femur fractures resulted in stronger construct than the DCS fixation in both cyclic loading and ultimate strength in biomechanical testing of a simulated A3 distal femur fracture.

  17. Q-angle in patellofemoral pain: relationship with dynamic knee valgus, hip abductor torque, pain and function☆

    Science.gov (United States)

    Almeida, Gabriel Peixoto Leão; Silva, Ana Paula de Moura Campos Carvalho e; França, Fábio Jorge Renovato; Magalhães, Maurício Oliveira; Burke, Thomaz Nogueira; Marques, Amélia Pasqual

    2016-01-01

    Objective To investigate the relationship between the q-angle and anterior knee pain severity, functional capacity, dynamic knee valgus and hip abductor torque in women with patellofemoral pain syndrome (PFPS). Methods This study included 22 women with PFPS. The q-angle was assessed using goniometry: the participants were positioned in dorsal decubitus with the knee and hip extended, and the hip and foot in neutral rotation. Anterior knee pain severity was assessed using a visual analog scale, and functional capacity was assessed using the anterior knee pain scale. Dynamic valgus was evaluated using the frontal plane projection angle (FPPA) of the knee, which was recorded using a digital camera during step down, and hip abductor peak torque was recorded using a handheld dynamometer. Results The q-angle did not present any significant correlation with severity of knee pain (r = −0.29; p = 0.19), functional capacity (r = −0.08; p = 0.72), FPPA (r = −0.28; p = 0.19) or isometric peak torque of the abductor muscles (r = −0.21; p = 0.35). Conclusion The q-angle did not present any relationship with pain intensity, functional capacity, FPPA, or hip abductor peak torque in the patients with PFPS. PMID:27069887

  18. Q-angle in patellofemoral pain: relationship with dynamic knee valgus, hip abductor torque, pain and function

    Directory of Open Access Journals (Sweden)

    Gabriel Peixoto Leão Almeida

    2016-04-01

    Full Text Available OBJECTIVE: To investigate the relationship between the q-angle and anterior knee pain severity, functional capacity, dynamic knee valgus and hip abductor torque in women with patellofemoral pain syndrome (PFPS. METHODS: This study included 22 women with PFPS. The q-angle was assessed using goniometry: the participants were positioned in dorsal decubitus with the knee and hip extended, and the hip and foot in neutral rotation. Anterior knee pain severity was assessed using a visual analog scale, and functional capacity was assessed using the anterior knee pain scale. Dynamic valgus was evaluated using the frontal plane projection angle (FPPA of the knee, which was recorded using a digital camera during step down, and hip abductor peak torque was recorded using a handheld dynamometer. RESULTS: The q-angle did not present any significant correlation with severity of knee pain (r = -0.29; p = 0.19, functional capacity (r = -0.08; p = 0.72, FPPA (r = -0.28; p = 0.19 or isometric peak torque of the abductor muscles (r = -0.21; p = 0.35. CONCLUSION: The q-angle did not present any relationship with pain intensity, functional capacity, FPPA, or hip abductor peak torque in the patients with PFPS.

  19. Comparison of the Lag Screw Placements for the Treatment of Stable and Unstable Intertrochanteric Femoral Fractures regarding Trabecular Bone Failure.

    Science.gov (United States)

    Celik, Talip; Mutlu, Ibrahim; Ozkan, Arif; Kisioglu, Yasin

    2016-01-01

    Background. In this study, the cut-out risk of Dynamic Hip Screw (DHS) was investigated in nine different positions of the lag screw for two fracture types by using Finite Element Analysis (FEA). Methods. Two types of fractures (31-A1.1 and A2.1 in AO classification) were generated in the femur model obtained from Computerized Tomography images. The DHS model was placed into the fractured femur model in nine different positions. Tip-Apex Distances were measured using SolidWorks. In FEA, the force applied to the femoral head was determined according to the maximum value being observed during walking. Results. The highest volume percentage exceeding the yield strength of trabecular bone was obtained in posterior-inferior region in both fracture types. The best placement region for the lag screw was found in the middle of both fracture types. There are compatible results between Tip-Apex Distances and the cut-out risk except for posterior-superior and superior region of 31-A2.1 fracture type. Conclusion. The position of the lag screw affects the risk of cut-out significantly. Also, Tip-Apex Distance is a good predictor of the cut-out risk. All in all, we can supposedly say that the density distribution of the trabecular bone is a more efficient factor compared to the positions of lag screw in the cut-out risk.

  20. Comparison of the Lag Screw Placements for the Treatment of Stable and Unstable Intertrochanteric Femoral Fractures regarding Trabecular Bone Failure

    Directory of Open Access Journals (Sweden)

    Talip Celik

    2016-01-01

    Full Text Available Background. In this study, the cut-out risk of Dynamic Hip Screw (DHS was investigated in nine different positions of the lag screw for two fracture types by using Finite Element Analysis (FEA. Methods. Two types of fractures (31-A1.1 and A2.1 in AO classification were generated in the femur model obtained from Computerized Tomography images. The DHS model was placed into the fractured femur model in nine different positions. Tip-Apex Distances were measured using SolidWorks. In FEA, the force applied to the femoral head was determined according to the maximum value being observed during walking. Results. The highest volume percentage exceeding the yield strength of trabecular bone was obtained in posterior-inferior region in both fracture types. The best placement region for the lag screw was found in the middle of both fracture types. There are compatible results between Tip-Apex Distances and the cut-out risk except for posterior-superior and superior region of 31-A2.1 fracture type. Conclusion. The position of the lag screw affects the risk of cut-out significantly. Also, Tip-Apex Distance is a good predictor of the cut-out risk. All in all, we can supposedly say that the density distribution of the trabecular bone is a more efficient factor compared to the positions of lag screw in the cut-out risk.

  1. 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

  2. A comparison of navigation template and traditional dynamic screw fixations for subtrochanteric fracture%应用动力髋螺钉治疗股骨转子下骨折导航模板与传统方法的效果比较

    Institute of Scientific and Technical Information of China (English)

    黄若昆; 谢鸣; 余嘉; 潘浩; 陈明; 任义军; 勘武生

    2013-01-01

    [目的]比较导航模板下与传统方法应用动力髋螺钉(DHS)内固定治疗股骨转子下骨折的效果.[方法]选择2009年2月~ 2010年12月期间接受导航模板与传统方法应用DHS治疗的16例股骨转子下骨折患者资料.随机分成常规手术组及导航模板组,两组均采用动力髋螺钉内固定.导航模板组通过数字化重建技术得到了基于动力髋螺钉个体化导航模板,重建的导航模板有较好的匹配性.采用Harris评分标准对术后随访1年手术效果进行评估.[结果]与传统组比较,导航模板组缩短了手术时间,减少了手术出血量,术后复查X线片见骨折端复位良好,内固定位置良好,应用Harris髋关节评分患者恢复良好,显著提高了手术的有效性,均达到了术前的预期效果.[结论]导航模板下DHS内固定具有缩短手术时间、术中出血量少、安全准确等优点,有其临床应用价值.%[Objective]To compare the navigation template and traditional method using dynamic hip screw(DHS)fixation in the treatment of subtrochanteric fractures. [ Method] Sixteen patients with subtrochanteric fracture were treated in our department from April 2009 to April 2010 and their clinical data were completed. All cases were randomly divided into two groups: the routine Operation and navigation template. In the navigation template group, subtrochanteric fracture mode was constructed by computer-aided design. Operation reposition on femoral subtrochanteric iracture was simulated, the module match with greater trochanter of femur,as well as the screw patch was designed. The post-surgury effect was evaluated by using Harris scores after 1 year follow-up. [Result]Compared to the routine group,the effect of navigation template group decreased operation duration and bleeding amount with excellent reposition. Harris scores for hip joint showed that the patients recovered well after operation. [ Conclusion] Computer-assisted preoperative design is

  3. 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.

  4. Hip Ultrasound

    Science.gov (United States)

    ... Physician Resources Professions Site Index A-Z Hip Ultrasound Hip ultrasound uses sound waves to produce pictures ... of Ultrasound Imaging of the Hip? What is Ultrasound Imaging of the Hip? Ultrasound images of the ...

  5. 微创经皮钢板固定术结合动力髁螺钉治疗青壮年股骨转子下不稳定骨折%Minimally invasive percutaneous plate osteosynthesis with dynamic condylar screw for comminuted proximal femoral fracture

    Institute of Scientific and Technical Information of China (English)

    吴劲风; 叶冬平; 李锋生; 梁伟国

    2010-01-01

    Objective To evaluate the technique, indications and results of minimally invasive per-cutaneous plate osteosynthesis (MIPPO) with dynamic condylar screw (DCS) for the treatment of young adults unstable comminuted subtrochanteric fracture. Methods From January 2001 to January 2006, 25 patients with unstable subtrechanteric fracture were treated. There were 18 males and 7 females, with the average age of 35 years (ranged from 25 to 40 years). 20 cases suffered traffic accident injuries, and 5 cases suffered falling down injuries. According to Seinsheimer classification, 15 cases fracture were ⅢA classification, 4 cases fracture were ⅢB classification, 6 cases were ⅣV classification. All of patients were closed fracture, and underwent MIPPO with DCS. The hip joint function was evaluated according to Harris's scale after surgeries. Results All patients were followed up from 9 to 24 months, with the average of 16 months. All subtrochanteric fractures were healed and the healing time was 3--4 months, with the average of 3.5 months. No patients suffered from the complications of plate fracture, screw loosening or cutting out, delayed healing, re-fracture, hip varus deformity, and limb shortening. According to Harris's scale, there were 14 eases excellent, 8 cases were good, 3 cases were fair on the hip joint function, the excellent and good rate was 92%. Conclusion M1PPO with DCS is the credible method for the treatment of young adults unstable comminut-ed subtrochanteric fracture, which can reduce operation complications, and benefit for fracture heal and hip function recovery.%目的 评估微创经皮钢板固定术(minimally invasive percutaneous plate osteosynthesis, MIPPO)结合动力髁螺钉(dynamic condylar screw,DCS)治疗青壮年股骨转子下不稳定骨折的临床价值.方法 2001年1月至2006年1月,手术治疗25例股骨转子下不稳定骨折患者,男18例,女7例;年龄25~40岁,平均35岁;左侧12例,右侧13例;车祸伤20例,坠落伤5

  6. Dynamic virtual simulation of the occurrence and severity of edge loading in hip replacements associated with variation in the rotational and translational surgical position.

    Science.gov (United States)

    Leng, Joanna; Al-Hajjar, Mazen; Wilcox, Ruth; Jones, Alison; Barton, David; Fisher, John

    2017-04-01

    Variation in the surgical positioning of total hip replacement can result in edge loading of the femoral head on the rim of the acetabular cup. Previous work has reported the effect of edge loading on the wear of hip replacement bearings with a fixed level of dynamic biomechanical hip separation. Variations in both rotational and translational surgical positioning of the hip joint replacement combine to influence both the biomechanics and the tribology including the severity of edge loading, the amount of dynamic separation, the force acting on the rim of the cup and the resultant wear and torque acting on the cup. In this study, a virtual model of a hip joint simulator has been developed to predict the effect of variations in some surgical positioning (inclination and medial-lateral offset) on the level of dynamic separation and the contact force of the head acting on the rim as a measure of severity of edge loading. The level of dynamic separation and force acting on the rim increased with increased translational mismatch between the centres of the femoral head and the acetabular cup from 0 to 4 mm and with increased cup inclination angle from 45° to 65°. The virtual model closely replicated the dynamics of the experimental hip simulator previously reported, which showed similar dynamic biomechanical trends, with the highest level of separation being found with a mismatch of 4 mm between the centres of the femoral head and acetabular cup and 65° cup inclination angle.

  7. Residual hip growth after pinning of slipped capital femoral epiphysis.

    Science.gov (United States)

    Breaud, Jean; Rubio, Amandine; Leroux, Julien; Griffet, Jacques

    2009-01-01

    Screwing of slipped capital femoral epiphysis must prevent its further slipping by prematurely fusing the physis. Whichever material is used, persistent femoral growth has been described, thereby increasing the risk of bone deformation. The objective of this study is to evaluate the residual growth after screwing of slipped capital femoral epiphysis. This study concerned 26 children, among which 13 children have been included, and 13 children excluded because of an incomplete clinical or radiological follow-up, or treatment by another technique. The pathological hip was treated with one screw (in eight cases) or two screws (in five cases). The controlateral hip was fixed with one screw. The different measures were taken on anteroposterior radiographs done the days after surgery, and on the first radiograph on which the growth plate had fused. Growth plate fusion was obtained after an average of 20 months. Each patient had presented a residual growth of at least one hip, thus 85% of the 26 fixed screws. Among the four hips, which did not grow, three were pathological, and were fixed by one screw (in one case) or two screws (in two cases), in a central or medial position. There was not any statistical relationship between the growth persistence and the other studied criteria. These results, proving the growth persistency, suggest that the follow-up must be extremely careful, as the number of threads crossing the growth plate will decrease, with the risk of loss of mechanical stability and reappearance of the femoral epiphysis slippage.

  8. Comparative Effectiveness of INTERTAN Intramedullary Nail and Sliding Hip Screw in Treating Intertrochanteric or Subtrochanteric Fracture of Elderly Patients%INTERTAN髓内钉与滑动髋螺钉治疗老年性粗隆间和粗隆下骨折的临床比较

    Institute of Scientific and Technical Information of China (English)

    章暐; 邹剑

    2014-01-01

    目的:比较INTERTAN髓内钉与滑动髋螺钉(DHS)治疗老年性粗隆间和粗隆下骨折的手术疗效。方法自2010年1月至2012年1月,对120例股骨粗隆间或粗隆下骨折患者分别行INTERTAN髓内钉或DHS固定治疗,其中INTERTAN组67例,DHS组53例。记录手术时间、术中出血量、术后引流量;进行术后疼痛评估、Harris髋骨评分、SF-36生活质量评估;记录并发症情况。结果本组中共有111例(INTERTAN组64例、DHS组47例)患者完成随访。两组间的手术时间无显著差异。DHS组的平均失血量及术后引流量较大,与INTERTAN组相比存在明显差异。VAS疼痛评分中,INTERTAN组术后3 d的VAS评分要优于DHS组,存在统计学差异;但术后3个月及12个月的随访中无明显差异。在术后3个月及12个月后,两组的Harris 髋关节评分和SF-36生活质量评分没有统计学差异。结论 INTERTAN和DHS治疗股骨粗隆间或粗隆下骨折,术后疼痛、功能、并发症的结果无明显差异。%Objective To compare the surgical efficacy between INTERTAN intramedullary nail and sliding hip screw in treating intertrochanteric or subtrochanteric fracture of old people. Methods From Jan 2010 to Jan 2012, 120 patients with Intertrochanteric or subtrochanteric Fractures were treated by INTERTAN intramedullary nail ( n=67) and sliding hip screw (n=53). Operation time, bleeding volume, amount of drainage, visual analogue scale (VAS) pain score, Harris hip score, SF-36 score and complications were recorded at each time points. Results Among all the patients, 111 patients (INTERTAN group: 64 cases; DHS group: 47 cases) were followed up for more than 1 year successfully. Bleeding volume and amount of drainage in INTERTAN group were larger than in DHS group. VAS score in INTERTAN group 3 days after operation was better than in DHS group, and there was no difference between the two groups 3 and 12 months after operation. There was no

  9. 动力髁螺钉治疗股骨近端不稳定骨折%Dynamic Condylar Screw for Treatment of Unstable Proximal Femoral Fractures

    Institute of Scientific and Technical Information of China (English)

    李明辉; 刘洋

    2011-01-01

    Objective To evaluate the efficacy of operative treatment for the Proximal femoral fracture with dynamic condyle screw (DCS). Methods From January 2004 to June 2009,37 cases of patients with Proximal femoral fracture (Reverse intertrochanteric femur fractures in 16 cases, 21 cases of intertrochanteric fracture ;Male 15,Female 22) was treated by DCS. 34 cases were followed up by 6 to 60 months in average age. The body mass index,operative time,blood loss,X ray projection times,the number of postoperative blood transfusion,postoperative wound drainage,postoperative neck-shaft angle,fracture healing time (patient began full weight bearing time) was statistics,and make Harris score. Results All patients were healed and there are no complications such as broken nails,broken boards,and other nonunion take place. 32 patients were followed up for 11~24 months time,with an average of 13 months.According to Harris score,the result was excellent in 15 cases,good in 12 cases, fair in4 and not satisfied with3. The excellent rate is 79. 41%. Conclusion Dynamic condylar screw is effective methods in treating unstable proximal femoral fractures. Application of DCS should be considered in elderly,obese patients. If you have to use the DCS,full weight-bearing should be extended.%目的 探讨应用动力髁螺钉(dynamic condylar screw,DCS)治疗股骨近端不稳定骨折的方法,评价其术中、术后情况及临床疗效.方法 自2004年1月至2009年6月采用闭合复位动力髁螺钉内固定治疗股骨近端骨折37例,其中男15例,女22例;股骨逆粗隆间骨折16例,股骨粗隆下骨折21例.在患者平均年龄、体重指数、手术时间、术中失血量、X线投照次数、术中及术后输血量、术后伤口引流量、术后颈于角、骨折愈合时间(患者开始完全负重时间)等方面进行统计,并进行Harris评分.结果 37例中34例得到6~60个月的随访,骨折全部愈合,无断钉、断板、骨

  10. Compressive Force With 2-Screw and 3-Screw Subtalar Joint Arthrodesis With Headless Compression Screws.

    Science.gov (United States)

    Matsumoto, Takumi; Glisson, Richard R; Reidl, Markus; Easley, Mark E

    2016-12-01

    Joint compression is an essential element of successful arthrodesis. Although subtalar joint compression generated by conventional screws has been quantified in the laboratory, compression obtainable with headless screws that rely on variable thread pitch to achieve bony contact has not been assessed. This study measured subtalar joint compression achieved by 2 posteriorly placed contemporary headless, variable-pitch screws, and quantified additional compression gained by placing a third screw anteriorly. Ten, unpaired fresh-frozen cadaveric subtalar joints were fixed sequentially using 2 diverging posterior screws (one directed into the talar dome, the other into the talar neck), 2 parallel posterior screws (both ending in the talar dome), and 2 parallel screws with an additional anterior screw inserted from the plantar calcaneus into the talar neck. Joint compression was quantified directly during screw insertion using a novel custom-built measuring device. The mean compression generated by 2 diverging posterior screws was 246 N. Two parallel posterior screws produced 294 N of compression, and augmentation of that construct with a third, anterior screw increased compression to 345 N (P < .05). Compression subsequent to 2-screw fixation was slightly less than that reported previously for subtalar joint fixation with 2 conventional lag screws, but was comparable when a third screw was added. Under controlled testing conditions, 2 tapered, variable-pitch screws generated somewhat less compression than previously reported for 2-screw fixation with conventional headed screws. A third screw placed anteriorly increased compression significantly. Because headless screws are advantageous where prominent screw heads are problematic, such as the load-bearing surface of the foot, their effectiveness compared to other screws should be established to provide an objective basis for screw selection. Augmenting fixation with an anterior screw may be desirable when conditions for

  11. 高速滚珠丝杠副动态接触特性求解%Solution of Dynamic Contact Characterics of High speed Ball Screw

    Institute of Scientific and Technical Information of China (English)

    徐正华; 孙杰

    2014-01-01

    高速滚珠丝杠副广泛应用于数控机床,其内部动态接触特性的求解是研究滚珠丝杠副传动性能的理论基础。在分析了动态特性方程组中各个方程的最终变量为实际接触角的基础上,提出了以接触角为变量迭代求解动态特性方程组的计算方法,并通过对接触角变化量的特点进行分析,准确地确定了接触角求解域。该方法较 Newton Raphson方法简化了计算工作量。最后运用该方法和New-ton Raphson方法对算例进行对比求解,计算结果表明了方法的可行性。%The high speed ball screw is widely used in numerically controlled machine tool,and the solution of it’s interior dynamic contact charac-terics is the theoretical basis to study the transmis-sion performance of ball screw.On the basis of an-alysing that ultimate variable for each equation were actual contact angles,a computing iterative method whose iteration variables were contact an-gles to solve the equation set of dynamic behavior was put forward.In addition,by analyzing charac-teristics of changes in contact angles,more specific solution domain of contact angles was determined accurately.The method avoids computational com-plexity of Newton Raphson.Finally,the example was solved by using the method and the Newton Raphson method separately,the consistency of re-sults indicates that the method is feasible.

  12. Hip Ultrasound

    Science.gov (United States)

    ... be used in infants to check for developmental dysplasia of the hip. Ultrasound is safe, noninvasive, and does not use ... be used to check the hips for developmental dysplasia of the hip (DDH), which in infants can range from a ...

  13. Hip Fracture

    Science.gov (United States)

    Diseases and Conditions Hip fracture By Mayo Clinic Staff A hip fracture is a serious injury, with complications that can be life-threatening. The risk of hip fracture rises with age. Older people are at a ...

  14. The Accuracy of Screw Axis Analysis Using Position Data from Anatomical Motion Studies.

    Science.gov (United States)

    1980-05-05

    Hip Motion ........ . 57 7-2 Screw Axis Analysis for the Sacro -iliac Joint. 57 viii " LIST OF FIGURES Figure Title Page 2-1 Systems Anthropometry Data...The piercing point selected for this test was an arbitrary point. The screw axis direction was selected so that there would be equal components in all...analyzed are the hip, and the sacro -iliac joint. The bone movements analyzed are the femur moving relative to the left inominate for hip motion, and the

  15. Estimation of Human Hip and Knee Multi-Joint Dynamics Using the LOPES Gait Trainer

    NARCIS (Netherlands)

    Koopman, Hubertus F.J.M.; van Asseldonk, Edwin H.F.; van der Kooij, Herman

    2016-01-01

    In this study, we present and evaluate a novel method to estimate multi-joint leg impedance, using a robotic gait training device. The method is based on multi-input–multi-output system identification techniques and is designed for continuous torque perturbations at the hip and knee joint

  16. 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...

  17. Stress analysis between“X”-shaped spine dynamic fixation and traditional pedicle screw fixation%“X”形弹性脊柱内固定与传统椎弓根内固定的应力分析

    Institute of Scientific and Technical Information of China (English)

    王宇; 梅继文; 穆尚强; 高峰; 黄锐

    2015-01-01

    背景:目前国内外许多学者研发了多种动态弹性脊柱内固定器,经过生物力学研究、动物实验及临床应用发现,尚无一种脊柱弹性内固定器得到临床上的普遍认可。  目的:比较自制“X”形弹性内固定器与传统椎弓根螺钉内固定的应力差异。  方法:根据成人脊柱影像学资料,分别建立“X”形弹性脊柱内固定器与传统椎弓根螺钉内固定系统三维有限元模型,比较两组模型在垂直压缩、屈、伸、侧屈、扭转时的力学差异。  结果与结论:两模型在垂直压缩状态应下的应力均小于屈、伸、侧屈及扭转状态下的应力;在垂直压缩、前屈、后伸、侧弯及旋转时,“X”形弹性脊柱内固定器的应力更多集中在“X”形连接棒上,而传统椎弓根螺钉内固定的应力更多集中在螺钉近棒段,且“X”形弹性脊柱内固定器螺钉所受应力明显小于传统椎弓根螺钉内固定(P<0.001)。表明“X”形弹性内固定器较传统椎弓根螺钉内固定系统更能分担螺钉应力,减少螺钉术后应力集中情况。%BACKGROUND:Many scholars have developed a variety of dynamic elastic spine fixator. After biomechanical research, animal experiments and clinical application found that no one elastic spine fixator was general y recognized clinical y. OBJECTIVE:To compare the stress difference between“X”-shaped spine dynamic fixation and traditional pedicle screw fixation. METHODS:Three-dimensional finite element models of“X”-shaped spine dynamic fixation and traditional pedicle screw fixation were established according to adult spine imaging data. Mechanical differences in vertical compression, flexion, extension, lateral bending and rotation were compared between the two groups. RESULTS AND CONCLUSION:The stress at vertical compression was lower than that at flexion, extension, lateral bending and rotation in both groups. The stress at

  18. DLC screw preload. Loosening prevention

    Directory of Open Access Journals (Sweden)

    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.

  19. Ball Screw Actuator Including a Compliant Ball Screw Stop

    Science.gov (United States)

    Wingett, Paul T. (Inventor); Hanlon, Casey (Inventor)

    2017-01-01

    An actuator includes a ball nut, a ball screw, and a ball screw stop. The ball nut is adapted to receive an input torque and in response rotates and supplies a drive force. The ball screw extends through the ball nut and has a first end and a second end. The ball screw receives the drive force from the ball nut and in response selectively translates between a retract position and a extend position. The ball screw stop is mounted on the ball screw proximate the first end to translate therewith. The ball screw stop engages the ball nut when the ball screw is in the extend position, translates, with compliance, a predetermined distance toward the first end upon engaging the ball nut, and prevents further rotation of the ball screw upon translating the predetermined distance.

  20. Progressive slip after removal of screw fixation in slipped capital femoral epiphysis: two case reports

    Directory of Open Access Journals (Sweden)

    Engelsma Yde

    2012-11-01

    Full Text Available Abstract Introduction In slipped capital femoral epiphysis the femoral neck displaces relative to the head due to weakening of the epiphysis. Early recognition and adequate surgical fixation is essential for a good functional outcome. The fixation should be secured until the closure of the epiphysis to prevent further slippage. A slipped capital femoral epiphysis should not be confused with a femoral neck fracture. Case presentation Case 1 concerns a 15-year-old boy with an adequate initial screw fixation of his slipped capital femoral epiphysis. Unfortunately, it was thought that the epiphysis had healed and the screw was removed after 11 weeks. This caused new instability with a progressive slip of the femoral epiphysis and subsequently re-fixation and a subtrochanteric correction osteotomy was obligatory. Case 2 concerns a 13-year-old girl with persistent hip pain after screw fixation for slipped capital femoral epiphysis. The screw was removed as lysis was seen around the screw on the hip X-ray. This operation created a new unstable situation and the slip progressed resulting in poor hip function. A correction osteotomy with re-screw fixation was performed with a good functional result. Conclusion A slipped epiphysis of the hip is not considered ‘healed’ after a few months. Given the risk of progression of the slip the fixation material cannot be removed before closure of the growth plate.

  1. 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

  2. Favorable outcome of a total hip arthroplasty with insufficient bone coverage of the roof reinforcement ring

    Directory of Open Access Journals (Sweden)

    Fernando M. Judas

    2015-01-01

    Conclusion: This result can be supported by the good fixation of the metal ring to the pelvis with screws, the adequate orientation of both components of the total hip arthroplasty, and the bone graft incorporation.

  3. Effect of dynamic hip system blade on the treatment of femoral neck fractures in elderly patients with osteoporosis

    Institute of Scientific and Technical Information of China (English)

    Zhao Wenbo; Liu Lei

    2014-01-01

    Objective:To discuss the curative effect of the dynamic hip system blade (DHS-blade) on the treatment of femoral neck fractures in elderly patients with osteoporosis.Methods:A retrospective study was conducted to analyse the clinical data of 60 elderly patients with osteoporosis who had been treated for femoral neck fractures with DHS-blade in our department between September 2012 and February 2014.There were 22 males and 38 females with a mean age of (66.8±3.2) years.According to the Singh Index Classification,all the patients' Singh index was below level 3.The Harris criterion and function recovery after operation were analysed.Results:All patients were followed up for 12-17 months (mean 14 months).No femoral head necrosis,femoral neck shortening,internal fixation loosening or backing out of the nails occurred.Bone nonunion was found in one case and he had a good recovery after total hip arthroplasty.The time for fracture healing ranged from 3-6 months (average 3.5 months).According to Harris criterion,35 cases were rated as excellent,22 good,2 fair and 1 poor.The Harris scale was significantly improved from 28.46±2.35 preoperatively to 91.98±3.26 at 6 months postoperatively (P<0.05).Conclusion:DHS-blade,being minimally invasive,allowing earlier postoperative exercise and avoiding the complications elicited by traditional internal fixation,is advisable for treatment of femoral neck fractured patients with osteoporosis.

  4. Dynamic condylar screw or hip joint(spanning)external fixator for treatment of pathological fractures of femoral neck and trochanter secondary to benign lesions

    Institute of Scientific and Technical Information of China (English)

    ZHANG Chun-lin; ZENG Bing-fang; DONG Yang; Daria brooks Terrell; Martin M.Malawer

    2008-01-01

    @@ The treatment of pathological fractures of the femoral neck and trochanteric region secondary to benign lesions can be a challenge for orthopaedic surgeons because of the size and nature of the lesions,the resulting bony defect,the risk of recurrence,the possible associated defortuities,and the risk of osteonecrosis.

  5. 高速空心滚珠丝杠副动态性能试验平台的研发%Development of testing platform of dynamic property of high-speed hollow ball screw unit

    Institute of Scientific and Technical Information of China (English)

    刘永平; 陈祯; 芮执元; 花志雄; 谢军太

    2012-01-01

    为了研究空心滚珠丝杠副在高速运行状态下的性能状况,研发了一种用于测试高速空心滚珠丝杠副动态性能参数的试验平台,给出了高速滚珠丝杠副动态性能参数测试的实现过程,介绍了试验台机械系统和控制系统的设计方案.利用该试验平台可以对滚珠丝杠副的加速度、速度、温升、热位移、定位精度等动态性能参数进行测试,为空心滚珠丝杠产品性能的改进提供可靠的实验数据参考.%In order to study the property of hollow screw unit under high-speed operation state, the testing platform used to measure the dynamic property parameters of high-speed hollow screw unit is developed, the realization method of the dynamic property parameters of high-speed screw unit is given, and the mechanical test and control system are introduced. Using the the platform parameter of acceleration, speed, temperature variation, thermal deformation and positioning accuracy and etc can be measured, and reliable reference experimental data for the improvement of products property can be acquired.

  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. Dynamic input to determine hip joint moments, power and work on the prosthetic limb of transfemoral amputees: ground reaction vs knee reaction

    OpenAIRE

    FROSSARD, Laurent; Cheze, Laurence; Dumas, Raphaël

    2011-01-01

    Background: Calculation of lower limb kinetics is limited by floor-mounted force-plates. Objectives: Comparison of hip joint moments, power and mechanical work on the prosthetic limb of a transfemoral amputee calculated by inverse dynamics using either the ground reactions (force-plates) or knee reactions (transducer). Study design: Comparative analysis. Methods: Kinematics, ground reaction and knee reaction data were collected using a motion analysis system, two forceplates, and a multi-axia...

  8. 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.

  9. 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.

  10. 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.

  11. 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...

  12. 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.)

  13. Hidden blood loss after surgery for hip fracture

    DEFF Research Database (Denmark)

    Foss, Nicolai Bang; Kehlet, H

    2006-01-01

    with aspirin, intra-operative hypotension and gastro-intestinal bleeding or ulceration were all independent predictors of blood loss. We conclude that total blood loss after surgery for hip fracture is much greater than that observed intra-operatively. Frequent post-operative measurements of haemoglobin......Our aim was to determine the total blood loss associated with surgery for fracture of the hip and to identify risk factors for increased blood loss. We prospectively studied 546 patients with hip fracture. The total blood loss was calculated on the basis of the haemoglobin difference, the number...... of transfusions and the estimated blood volume. The hidden blood loss, in excess of that observed during surgery, varied from 547 ml (screws/ pins) to 1473 ml (intramedullary hip nail and screw) and was significantly associated with medical complications and increased hospital stay. The type of surgery, treatment...

  14. Hidden blood loss after surgery for hip fracture

    DEFF Research Database (Denmark)

    Foss, N B; Kehlet, H

    2006-01-01

    Our aim was to determine the total blood loss associated with surgery for fracture of the hip and to identify risk factors for increased blood loss. We prospectively studied 546 patients with hip fracture. The total blood loss was calculated on the basis of the haemoglobin difference, the number...... of transfusions and the estimated blood volume. The hidden blood loss, in excess of that observed during surgery, varied from 547 ml (screws/ pins) to 1473 ml (intramedullary hip nail and screw) and was significantly associated with medical complications and increased hospital stay. The type of surgery, treatment...... with aspirin, intra-operative hypotension and gastro-intestinal bleeding or ulceration were all independent predictors of blood loss. We conclude that total blood loss after surgery for hip fracture is much greater than that observed intra-operatively. Frequent post-operative measurements of haemoglobin...

  15. Ipsilateral Traumatic Posterior Hip Dislocation, Posterior Wall and Transverse Acetabular Fracture with Trochanteric Fracture in an adult: Report of First Case

    Directory of Open Access Journals (Sweden)

    Skand Sinha

    2013-10-01

    Full Text Available Introduction: Posterior dislocation of the hip joint with associated acetabular and intertrochanteric fracture is a complex injury. Early recognition, prompt and stable reduction is needed of successful outcome. Case Report: 45 year old male patient presented with posterior dislocation of the hip with transverse fracture with posterior wall fracture of acetabulam and intertrochanteric fracture on the ipsilateral side. The complex fracture geometry was confirmed by CT scan. The patient was successfully managed by open reduction and internal fixation of intertrochanteric fracture was achieved with dynamic hip screw (DHS plate fixation followed by fixation of acetabular fracture with reconstruction plate. Conclusion: Hip dislocation combined with acetabular fracture is an uncommon injury; this article presents a unique case of posterior wall and transverse fractures of ipsilateral acetabulum with intertrochanteric fracture in a patient who sustained traumatic posterior hip dislocation. Early surgical intervention is important for satisfactory outcomes of such complex fracture-dislocation injuries. Keywords: Hip dislocation; acetabular fractures; intertrochanteric fracture; operative treatment.

  16. 滚珠丝杠副动态接触特性分析%Studies on dynamic contact characteristics of ball screws

    Institute of Scientific and Technical Information of China (English)

    刘更; 张晓彩; 马尚君; 佟瑞庭

    2013-01-01

    Based on Hertz contact theory, a computational method of contact deformation in operating process of ball screws is established in terms of variable contact angles and the centrifugal force. Through the force balance equations, contact deformation in operating process is derived. Taking a ball screw as an example, the influence of its operating condition, contact angles and helix angle on contact characteristics is studied by numerical method. Analysis indicates that the contact deformation on the side of screw decreases and that of nut increases when the screw rotation speed increases and there exists a speed that the later is greater than the former. At the same time, the difference between contact angles increases. Variety of contact angles increase as the axial load decreases, which leads to higher influence on contact deformations. Contact deformations decrease as the contact angle and helix angle increase.%基于Hertz接触理论,在考虑运行工况引起的接触角变化扣离心力的基础上,通过受力分析,建立了滚珠丝杠副的力平衡方程并提出一种计算滚珠丝杠副运转过程中接触变形的方法.以某型号滚珠丝杠副为例,分析了轴向载荷、丝杠转速、接触角和螺旋角对滚珠丝杠副接触特性的影响.分析结果表明,转速增大时丝杠侧的接触变形减小,螺母侧的接触变形增大,两侧接触角的差值增大,当转速增大到一定程度时,螺母侧的接触变形会大于丝杠侧;载荷越小,运转过程中接触角的变化越大,对接触变形的影响也较大;接触变形随接触角和螺旋角的增大而减小.

  17. Modeling for dynamic contact angle of ball screw mechanism aimed to structural parameters%面向结构参数的滚珠丝杠副动态接触角建模

    Institute of Scientific and Technical Information of China (English)

    李梦奇; 庾辉; 李冬英; 王斌; 张根保

    2016-01-01

    Ball screw mechanism is one of the key parts in mechanical and electronic products especially in precision machineries due to its high transmission efficiency, long service life and high precision, high carrying capacity and positioning accuracy,which is determined by the contact angle formed between nut and screw. Aimed at the current problems in universal and limited application, which resulted from the specific structure parameters, this paper establishes the relationship between contact angle and ball screw’s structure parameters, as well as the model of the dynamic contact angle of ball screw mechanism combined with the geometric parameters of the ball and the raceway between nut and screw.The relationship between force and deformation in ball and raceway is got by using the Hertz contact theory, which is used to solve the stiffness in contact area between screw and nut. The relationship between ball’s rotation and revolution speed and screw’s rotation speed is got by using the raceway control theory, which is used to solve the centrifugal force and gyroscopic moment formed under working conditions. The structural model of the nonlinear equations of contact angle is got, in which the variable includes clearance, nominal diameter, ball diameter, helix angle and ball number. The solving procedure of dynamic contact angle is given based on the Newton-Raphson method. The influence of structure parameters on contact angle of ball screw mechanism under different working conditions is studied through the example analysis, and verified by contrasting the influence of ball screw’s rotational speed on contact angles with a specific structure. The results show that the inner contact angles in screw raceway are always greater than the external angles in nut raceway under working conditions. The inner contact angles increase with the increasing of screw’s rotational speed, and in contrast, the external contact angles decrease. Both the values of inner contact

  18. 旋量理论的变胞机构全构态动力学模型%Configuration-complete dynamic model of metamorphic mechanism based on screw theory

    Institute of Scientific and Technical Information of China (English)

    刘秀莲; 张校东

    2013-01-01

    为丰富和发展机构学理论,通过引入切断铰,将空间串并联机构的运动学分析问题转化为开链机构和局部闭链机构的运动学分析子问题,基于旋量理论建立切断铰空间机构的运动学和动力学模型.采用旋量理论和Kane方法对五杆两自由度闭链变胞机构的广义主动力和广义惯性力进行了计算,并建立切割变胞机构的全构态动力学方程.该方法为变胞机构的动力学建模提供了参考依据.%This paper is an attempt to enrich and develop the theory of mechanism by transforming motion analysis problem of spatial series-parallel mechanism into motion analysis sub-problem of open chain and closed-chain mechanism as a result of cut-off joint and developing kinematics and dynamics models of spatial mechanism based on screw theory.The paper describes the calculation of the inertia main force and the inertia main torque using screw theory and Kane method in the case of the two DOF of five rods closed chain metamorphic mechanism and the development of the configuration-complete dynamic model for metamorphic mechanism.This model provides some reference for dynamics model of metamorphic mechanism.

  19. 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 ...

  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. Hip arthroscopy

    Directory of Open Access Journals (Sweden)

    Henrique Antônio Berwanger de Amorim Cabrita

    2015-06-01

    Full Text Available Hip arthroscopy is a safe method for treating a variety of pathological conditions that were unknown until a decade ago. Femoroacetabular impingement is the commonest of these pathological conditions and the one with the best results when treated early on. The instruments and surgical technique for hip arthroscopy continue to evolve. New indications for hip arthroscopy has been studied as the ligamentum teres injuries, capsular repair in instabilities, dissection of the sciatic nerve and repair of gluteal muscles tears (injuries to the hip rotator cuff, although still with debatable reproducibility. The complication rate is low, and ever-better results with fewer complications should be expected with the progression of the learning curve.

  2. Rose Hip

    Science.gov (United States)

    ... dropsy or edema), gout, back and leg pain (sciatica), diabetes, high cholesterol, weight loss, high blood pressure, ... Painful menstruation. Some evidence suggests that applying an aromatherapy formula containing lavender, clary sage, and rose hip ...

  3. Hip ultrasound

    Energy Technology Data Exchange (ETDEWEB)

    Martinoli, Carlo, E-mail: carlo.martinoli@libero.it [Radiologia, DISC, Università di Genova, Largo Rosanna Benzi 8, I-16132 Genoa (Italy); Garello, Isabella; Marchetti, Alessandra; Palmieri, Federigo; Altafini, Luisa [Radiologia, DISC, Università di Genova, Largo Rosanna Benzi 8, I-16132 Genoa (Italy); Valle, Maura [Radiologia, Gaslini Children Hospital, Genova (Italy); Tagliafico, Alberto [Radiologia, National Institute for Cancer Research, Genoa (Italy)

    2012-12-15

    In newborns, US has an established role in the detection and management of developmental dysplasia of the hip. Later in childhood, when the limping child is a major diagnostic dilemma, US is extremely helpful in the identification of the varied disease processes underlying this condition, as transient synovitis, septic arthritis, Perthes disease and slipped femoral capital epiphysis. In adolescent practicing sporting activities, US is an excellent means to identify apophyseal injures about the pelvic ring, especially when avulsions are undisplaced and difficult-to-see radiographically. Later on, in the adulthood, US is an effective modality to diagnose tendon and muscle injuries about the hip and pelvis, identify effusion or synovitis within the hip joint or its adjacent bursae and guide the treatment of these findings. The aim of this article is to provide a comprehensive review of the most common pathologic conditions about the hip, in which the contribution of US is relevant for the diagnostic work-up.

  4. UNCEMENTED PRIMARY TOTAL HIP ARTHROPLASTY FOR OSTEONECROSIS OF HIP WITH SECONDARY OSTEOARTHRITIS IN YOUNG ADULTS

    Directory of Open Access Journals (Sweden)

    Chatla

    2016-03-01

    Full Text Available BACKGROUND Osteonecrosis of the femoral head is a progressive disease that generally affects patients in the third through fifth decade of life, if left untreated. Currently, 18% of all Total Hip Arthroplasty performed in USA are done for Osteonecrosis.(1 The aetiology for the Osteonecrosis varies from idiopathic, alcohol intoxication, steroid abuse or due to childhood hip disorders and hip trauma. We have selected 40 patients suffering from advanced femoral head osteonecrosis with subchondral collapse leading to Osteoarthritis of hip in young adults, treated by uncemented primary total hip replacement. This study is aimed to suggest that uncemented total hip arthroplasty can be applied predictably to this younger, potentially more active patient population. MATERIAL AND METHODS We have done 54 uncemented primary hips in 40 cases with mean follow-up of 5.5 years. The average age of the patient at the time of surgery was 43 years. All the hips are clinically and radiologically examined both pre- and post-operatively. All the cases are operated through postero-lateral approach and have used the fully Hydroxyapatite coated femoral straight stem designed for press fit insertion and hemispherical HA-coated cup inserted with press fit and in few cases we used an HA-coated screw. The patients are under regular follow-up. RESULTS All the patients are reviewed at 6 weeks, 3 months, 6 months and yearly thereafter. The clinical and functional status was recorded using the Harris Hip Score and WOMAC Hip Score. The mean Harris score has improved from an average of 44 points to an average of 93 points postoperatively; 94% showed good-to-excellent results, 2% of cases had shortening, one case developed hip dislocation after two weeks due to unguarded physiotherapy. CONCLUSION The short-term results of cementless total hip arthroplasty in patients with Osteonecrosis of the femoral head were encouraging. We await further follow-up to see if these promising

  5. Treatment of subtrochanteric femur fractures with minimal invasion dynamic hip plate through percutaneous limited open reduction%经皮有限切开新型微创动力髋钢板治疗股骨转子下骨折

    Institute of Scientific and Technical Information of China (English)

    翁益民; 孔建中; 潘骏; 水小龙; 冯永增; 郭晓山

    2013-01-01

    Objective To investigate the possibility,surgical methods,outcome and surgical indications of minimal invasion dynamic hip plate (MIDHP) through percutaneous limited open reduction in treatment of subtrochanteric femur fractures.Methods All cases underwent percutaneous limited open reduction with MIDHP.Duration of operation,intraoperative bleeding volume,length of incision,incidence of intra-or post-operative complications of all case were recorded.X-ray films were reviewed periodically after operation to analyze aspects of fracture displacement,loosening of intemal fixation,screw cutting femoral neck,screw penetrating out of or withdrawing from femoral head,bending or breaking of internal fixation,and fracture healing.Hip joint function was evaluated according to Huang' s criteria.Results Operation lasted for 45-55 minutes (average 50 minutes),showing the incision length of 4.0-5.0 cm (average 4.5 cm) and blood loss of 50-200 ml (average 150 ml).A total of 21 cases were enrolled in the study and were followed up for 6-28 months (average 18 months).In the follow-up,loosening or bending of internal fixation,fracture displacement,screw cut-out,and screw penetrating or withdrawing from femoral head did not occur.In the meantime,incision,bone,and joint were not infected.All cases had bony fusion within 3 months with the fracture healing rate of 100%.According to Huang' s criteria,hip function was excellent in 19 cases and good in two.Conclusions MIDHP with percutaneous limited open reduction is characterized by less trauma,small incision,less blood loss,less postoperative complications,firm fixation,early functional exercise,free load,and good hip functional recovery and hence is suitable for cases of different subtrochanteric femur fractures,especially for cases combined with osteoporosis.%目的 探讨应用新型微创动力髋钢板(minimal invasion dynamic hip plate,MIDHP)经皮小切口治疗股骨转子下骨折的可行性、手术方法、

  6. 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.

  7. 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.

  8. Current status of noncemented hip implants.

    Science.gov (United States)

    Harris, W H

    1987-01-01

    Recently the operative techniques, instrumentation, design, and material properties of bony ingrowth total hip replacement have been greatly improved. I prefer a hemispherical acetabular component fixed with screws going through the metal shell. The titanium mesh allows microinterlock with new bone, and macrointerlock is obtained by adding bone graft into the unused screw holes. The femoral component, made of Tivanium with titanium mesh attached to it by a new process called diffusion bonding, retains superalloy fatigue strength characteristics. An intimate press fit is assured by the specific operative technique, and both the fiber mesh and the collar provide proximal stress transfer. The design affords a nondestructive method for removal if necessary. The short-term clinical results are promising; most patients function as well as with cemented total hip replacement. The incidence of thigh pain has been significantly reduced since prior reports of cementless total hip replacement; however, a few patients still have thigh pain. The results in revision surgery are also promising, but as in cemented total hip replacement, the functional capacity of revision cases is usually lower than primary cases. There is an increased capacity to correct complex and difficult acetabular problems with this acetabular component. Obviously, long-term data are needed to establish the behavior of these implants over the immediate and long term.

  9. Biomechanical study of novel minimally invasive dynamic hip plate for femoral subtrochanteric fractures%新型微创动力髋钢板治疗股骨转子下骨折生物力学研究

    Institute of Scientific and Technical Information of China (English)

    翁益民; 水小龙; 孔建中; 潘骏; 洪建军; 陈华; 郭晓山

    2013-01-01

    目的 通过对新鲜尸体标本的力学研究,比较新型微创动力髋钢板(minimal invasion dynamic hip plate,MIDHP)和动力髁螺钉(dynamic condylar screw,DCS)固定股骨转子下骨折的生物力学性能. 方法 全部标本先制作Seinsheimer分型ⅡA型股骨转子下骨折模型,按随机排列表法分组进行DCS和MIDHP内固定.根据实验要求以自凝型牙托粉包埋股骨头及股骨远端.先行扭转强度试验,再行压缩强度试验,然后进行破坏试验,记录极限载荷.对所得数据进行统计学处理. 结果 标本扭转强度测试表明,在扭转至3°内两组标本均基本稳定.扭转1.5°时DCS组扭矩为(3.16 ±0.13)N·m,MIDHP组为(3.31 ±0.27)N·m,两组扭矩及扭转刚度比较差异无统计学意义,两种内固定器抗旋转性能相近.标本压缩强度测试表明,800 N载荷时DCS组压缩刚度为(532.27±61.02) N/mm,MIDHP组为(581.98±77.56) N/mm,压缩位移及刚度MIDHP组明显高于DCS组(P<0.05).破坏试验表明,DCS组极限载荷为(2 994.38 ±244.81)N,MIDHP组为(3 322.13±141.21)N,MIDHP组明显大于DCS组(P<0.01). 结论 MIDHP设计合理,抗旋转能力强,抗压缩能力强于DCS,治疗股骨转子下骨折时比DCS更具生物力学优势,可以微创操作,值得推广.%Objective To perform a mechanical test of fresh cadaver specimens and compare the biomechanical properties of the novel minimal invasion dynamic hip plate (MIDHP) and the dynamic condylar screw (DCS) in treatment of subtrochanteric fractures of the femur.Methods All specimens were firstly used to simulate models of Seinsheimer type ⅡA subtrochanteric fractures of the femur,which were later divided into DCS group and MIDHP group.Based on experimental requirements,the femoral head and distal femur were embedded using seff-freezing type dental base acrylic resin powder.Torsion strength test was given in the first place,succeeded by compression strength test.Finally,destructive test was made to record the

  10. Hip Microfracture

    Science.gov (United States)

    McGill, Kevin C.; Bush-Joseph, Charles A.; Nho, Shane J.

    2010-01-01

    Microfracture is a marrow-stimulating technique used in the hip to treat cartilage defects associated with femoro-acetabular impingement, instability, or traumatic hip injury. These defects have a low probability of healing spontaneously and therefore often require surgical intervention. Originally adapted from the knee, microfracture is part of a spectrum of cartilage repair options that include palliative procedures such as debridement and lavage, reparative procedures such as marrow-stimulating techniques (abrasion arthroplasty and microfracture), and restorative procedures such as autologous chondrocyte implantation and osteochondral allograft/autografts. The basic indications for microfracture of the hip include focal and contained lesions typically less than 4 cm in diameter, full-thickness (Outerbridge grade IV) defects in weightbearing areas, unstable lesions with intact subchondral bone, and focal lesions without evidence of surrounding chondromalacia. Although not extensively studied in the hip, there are some small clinical series with promising early outcomes. Although the widespread use of microfracture in the hip is hindered by difficulties in identifying lesions on preoperative imaging and instrumentation to circumvent the femoral head, this technique continues to gain acceptance as an initial treatment for small, focal cartilage defects. PMID:26069544

  11. How Reliable Are The Threaded Locking Screws?

    OpenAIRE

    Karaarslan, Ahmet; Karakaslı, Ahmet; Karcı, Tolga; Aycan, Hakan; Sesli, Erhan

    2015-01-01

    Objectives: A frequent problem for interlocking nailing, that affects the treatment of the fracture is locking screw deformation. The research question is whether bending resistance is different between high, low and unthreaded locking screws of interlocking femoral nails. Materials and methods. : We used 90 screws for nine groups, ten screws for each group in this experimental study. We performed three-point bending tests on six group of 5 mm screws (titanium, stainless steel, crossed with u...

  12. Subject-specific hip geometry affects predicted hip joint contact forces during gait.

    Science.gov (United States)

    Lenaerts, G; De Groote, F; Demeulenaere, B; Mulier, M; Van der Perre, G; Spaepen, A; Jonkers, I

    2008-01-01

    Hip loading affects bone remodeling and implant fixation. In this study, we have analyzed the effect of subject-specific modeling of hip geometry on muscle activation patterns and hip contact forces during gait, using musculoskeletal modeling, inverse dynamic analysis and static optimization. We first used sensitivity analysis to analyze the effect of isolated changes in femoral neck-length (NL) and neck-shaft angle (NSA) on calculated muscle activations and hip contact force during the stance phase of gait. A deformable generic musculoskeletal model was adjusted incrementally to adopt a physiological range of NL and NSA. In a second similar analysis, we adjusted hip geometry to the measurements from digitized radiographs of 20 subjects with primary hip osteoarthrosis. Finally, we studied the effect of hip abductor weakness on muscle activation patterns and hip contact force. This analysis showed that differences in NL (41-74 mm) and NSA (113-140 degrees ) affect the muscle activation of the hip abductors during stance phase and hence hip contact force by up to three times body weight. In conclusion, the results from both the sensitivity and subject-specific analysis showed that at the moment of peak contact force, altered NSA has only a minor effect on the loading configuration of the hip. Increased NL, however, results in an increase of the three hip contact-force components and a reduced vertical loading. The results of these analyses are essential to understand modified hip joint loading, and for planning hip surgery for patients with osteoarthrosis.

  13. Torsional stiffness after subtalar arthrodesis using second generation headless compression screws: Biomechanical comparison of 2-screw and 3-screw fixation.

    Science.gov (United States)

    Riedl, Markus; Glisson, Richard R; Matsumoto, Takumi; Hofstaetter, Stefan G; Easley, Mark E

    2017-06-01

    Subtalar joint arthrodesis is a common operative treatment for symptomatic subtalar arthrosis. Because excessive relative motion between the talus and calcaneus can delay or prohibit fusion, fixation should be optimized, particularly in patients at risk for subtalar arthrodesis nonunion. Tapered, fully-threaded, variable pitch screws are gaining popularity for this application, but the mechanical properties of joints fixed with these screws have not been characterized completely. We quantified the torsion resistance of 2-screw and 3-screw subtalar joint fixation using this type of screw. Ten pairs of cadaveric subtalar joints were prepared for arthrodesis and fixed using Acutrak 2-7.5 screws. One specimen from each pair was fixed with two diverging posterior screws, and the contralateral joint was fixed using two posterior screws and a third screw directed through the anterior calcaneus into the talar neck. Internal and external torsional loads were applied and joint rotation and torsional stiffness were measured at two torque levels. Internal rotation was significantly less in specimens fixed with three screws. No difference was detectable between 2-screw and 3-screw fixation in external rotation or torsional stiffness in either rotation direction. Both 2-screw and 3-screw fixation exhibited torsion resistance surpassing that reported previously for subtalar joints fixed with two diverging conventional lag screws. Performance of the tapered, fully threaded, variable pitch screws exceeded that of conventional lag screws regardless of whether two or three screws were used. Additional resistance to internal rotation afforded by a third screw placed anteriorly may offer some advantage in patients at risk for nonunion. Copyright © 2017. Published by Elsevier Ltd.

  14. Effect of Dynamic Platform Lateral Step-Up versus Stable Platform Lateral Step-Up Weight Bearing Exercise in Hip Abductor Strengthening on Healthy Male Volunteers - Randomized Clinical Trial

    Directory of Open Access Journals (Sweden)

    Jagatheesan Alagesan

    2011-07-01

    Full Text Available Objective & Background: To determine the effect of the dynamic platform lateral step-up and stable platform lateral step-up weight bearing standing exercise in strengthening of hip abductor. Many researchers have reported that strengthening of hip muscles as important component especially hip abductors in lower extremity rehabilitation program. Study Design: Single blinded randomized comparative clinical trial. Methodology: Sixty five healthy college going male subjects (Age group of 18 – 24 years volunteered for this study. They were randomly assigned to one of the 2 groups. One group received the dynamic platform lateral step-up and the other received stable platform lateral step-up weight bearing standing exercise. The strength measurements were recorded using hand held dynamometer. Results: The results indicate that both groups had a positive effect on the outcome measures. The strength of hip abductors in dynamic platform group improved from a mean value (SD of 19.47(3.59 to 26.93(3.19 and in stable platform group from 19.07(2.32 to 22.67(2.46. Significant difference is also observed between the two groups at p value .05. Conclusion: The study shows that dynamic platform lateral step-up exercise is more beneficial than stable platform lateral step-up weight bearing standing exercise in improving hip abductor muscle strength.

  15. Safety of computer-assisted surgery for cannulated hip screws

    NARCIS (Netherlands)

    Hamelinck, H.K.M; Haagmans, M.; Snoeren, M.M.; Biert, J.; Vugt, A.B. van; Frolke, J.P.M.

    2007-01-01

    Computer-assisted orthopaedic surgery has developed considerably during the past few years. Several manufacturers produce hardware and software for use in trauma surgery. Validation of these systems before clinical application is mandatory to be sure they work accurately and safely. The accuracy of

  16. 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.

  17. Navigated percutaneous screw fixation of a periprosthetic acetabular fracture.

    Science.gov (United States)

    Gras, Florian; Marintschev, Ivan; Klos, Kajetan; Fujak, Albert; Mückley, Thomas; Hofmann, Gunther O

    2010-10-01

    Periprosthetic fractures are severe complications of total hip arthroplasty with increasing incidence. Most fractures are localized around the femoral component of prosthesis, whereas periacetabular fractures are rare and their management is difficult. In most cases, an operative procedure with revision and exchange of the acetabular cup is necessary. The approaches are demanding and an increased risk of complications is reported. We present the case of a female patient with a cementless total hip arthroplasty due to severe arthritis, suffering of an infratectal transverse periprosthetic fracture. After an initial conservative treatment attempt, we performed a minimally invasive screw fixation using navigated 2-dimensional fluoroscopic guidance. In this report, the literature for treatment recommendations is reviewed and the chosen navigation technique discussed. Copyright © 2010. Published by Elsevier Inc.

  18. Hip Replacement

    Science.gov (United States)

    ... The most common cause of damage is osteoarthritis. Osteoarthritis causes pain, swelling, and reduced motion in your joints. It can interfere with your daily activities. If other treatments such as physical therapy, pain medicines, and exercise haven't helped, hip ...

  19. Subject-specific hip geometry and hip joint centre location affects calculated contact forces at the hip during gait.

    Science.gov (United States)

    Lenaerts, G; Bartels, W; Gelaude, F; Mulier, M; Spaepen, A; Van der Perre, G; Jonkers, I

    2009-06-19

    Hip loading affects the development of hip osteoarthritis, bone remodelling and osseointegration of implants. In this study, we analyzed the effect of subject-specific modelling of hip geometry and hip joint centre (HJC) location on the quantification of hip joint moments, muscle moments and hip contact forces during gait, using musculoskeletal modelling, inverse dynamic analysis and static optimization. For 10 subjects, hip joint moments, muscle moments and hip loading in terms of magnitude and orientation were quantified using three different model types, each including a different amount of subject-specific detail: (1) a generic scaled musculoskeletal model, (2) a generic scaled musculoskeletal model with subject-specific hip geometry (femoral anteversion, neck-length and neck-shaft angle) and (3) a generic scaled musculoskeletal model with subject-specific hip geometry including HJC location. Subject-specific geometry and HJC location were derived from CT. Significant differences were found between the three model types in HJC location, hip flexion-extension moment and inclination angle of the total contact force in the frontal plane. No model agreement was found between the three model types for the calculation of contact forces in terms of magnitude and orientations, and muscle moments. Therefore, we suggest that personalized models with individualized hip joint geometry and HJC location should be used for the quantification of hip loading. For biomechanical analyses aiming to understand modified hip joint loading, and planning hip surgery in patients with osteoarthritis, the amount of subject-specific detail, related to bone geometry and joint centre location in the musculoskeletal models used, needs to be considered.

  20. Dynamic loading of the knee and hip joint and compensatory strategies in children and adolescents with varus malalignment.

    Science.gov (United States)

    Stief, Felix; Böhm, Harald; Schwirtz, Ansgar; Dussa, Chakravarthy Ugandhar; Döderlein, Leonhard

    2011-03-01

    Three-dimensional gait analysis is a diagnostic tool that can be used to gain a better understanding of the relationship between joint loading and the onset or progression of articular cartilage degeneration in subjects with varus malalignment. The purpose of the present study was to investigate knee and hip joint angles and moments in children and adolescents with pathological varus alignment of the knee without signs of knee osteoarthritis (OA). Moreover, we wanted to know if compensatory mechanisms are present in this young patient group. Fourteen, otherwise healthy patients with varus malalignment of the knee and 15 healthy control subjects were analysed. Patients showed a reduced knee extension and a significantly lower maximum knee extension moment in terminal stance compared to controls. The maximum knee adduction moment in mid and terminal stance and the maximum hip abduction moment in loading response were significantly higher in the patient group. In the transverse plane, abnormally increased knee internal rotation and hip external rotation moments were present in patients with varus malalignment. These findings imply that varus malalignment is not an isolated problem in the frontal plane. In contrast to adult patients with established medial knee OA, the young patients assessed in the present study did not show typical compensatory mechanisms such as increased foot progression angle or reduced walking speed. This suggests that children and adolescents with varus malalignment of the knee probably do not need to alter their spatio-temporal gait parameters in order to decrease knee joint loading.

  1. Pediatric Hip Fractures in California: Results from a Community-Based Hip Fracture Registry.

    Science.gov (United States)

    Prentice, Heather A; Paxton, Elizabeth W; Hunt, Jessica J; Grimsrud, Christopher D; Weiss, Jennifer M

    2017-01-01

    Hip fracture registries offer an opportunity to identify and to monitor patients with rare conditions and outcomes, including hip fractures in pediatric patients. To report patient demographics and surgical outcomes of pediatric patients treated surgically for hip fractures in a large integrated health care system. Pediatric patients (fracture) with hip fractures were identified between 2009 and 2012 using our health care system's hip fracture registry. Patient characteristics, type of fracture, surgical treatment, and short-term complications. Among 39 patients identified, 31 (79.5%) were male, and the median age was 15 years old (interquartile range: 11-17 years). Most patients were Hispanic (n = 17, 43.6%) or white (n = 14, 35.9%). There were 8 patients (20.5%) with 15 comorbidities. Delbet Type IV (intertrochanteric) fractures were the most common fracture type (n = 22, 56.4%), and fixation method was equally distributed between intramedullary, screw and sideplate, and screws (n = 12, 30.8% for each). Most surgeries were performed by medium-volume surgeons (n = 22, 56.4%) at medium- and high-volume hospitals (n = 37, 94.9%). Three 90-day readmissions (7.7%), 1 infection (2.6%), 1 malunion (2.6%), and 1 revision (2.6%) were observed in this cohort during the study period. In our series using registry data, hip fractures younger than age 21 years were more common in boys and Hispanic patients. Intertrochanteric fractures (Delbet Type IV) were the most frequently observed type in our community-based hip fracture registry. Short-term complications were infrequent.

  2. 基于旋量的油罐清洗机器人动力学建模及仿真%Oil Tank Cleaning Robot Dynamics Modeling and Simulation Based on Screw Theory

    Institute of Scientific and Technical Information of China (English)

    谢阶齐; 周利坤; 冯建伟

    2012-01-01

    The oil tank cleaning robot is a kind of special cleaning robot, and carry on the dynamics analysis and modeling is the basis of motion control. Based on the dynamics of the screw theory of analysis method, through the virtual linkage mechanism of fixed and convert equivalent single - degree - of - freedom joint open chain system, and with the spiral and exponential product of mathematical tools, the dynamic equation and jacobian matrix were built and the kinetic energy of the whole system was deduced. Lagrange - d and Alemert principle were applied to establish the system dynamic model. Finally, through the ADAMS simulation software, the robot system and simulation were carried out to establish the control strategy, control method, trajectory planning.%油罐清洗机器人是特种清洗机器人的一种,对清洗机器动态进行动力学分析和建模是分析运动控制稳定性的基础.为保证操作的稳定性和安全性,根据旋量理论的动力学的分析原理,通过虚拟连杆机构转换成等效的固定基单自由度关节的开链系统,利用螺旋和指数积等数学工具建立动力学方程和雅可比矩阵,推导出整个系统的动力特性.应用Lagranged、Alemert原理建立系统的动力学模型,最后,通过ADAMS仿真软件,对机器人系统进行仿真,从而为建立控制策略、控制方法、轨迹规划打下坚实的基础.

  3. 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.

  4. Combining of small fragment screws and large fragment plates for open reduction and internal fixation of periprosthetic humeral fractures.

    Science.gov (United States)

    Seybold, Dominik; Citak, Mustafa; Königshausen, Matthias; Gessmann, Jan; Schildhauer, Thomas A

    2011-10-01

    Operative treatment of periprosthetic humeral fractures in elderly patients with osteoporotic bone requires a stable fixations technique. The combination of 3.5 cortical screws with washers in a 4.5 Arbeitsgemeinschaft für Osteosynthesefragen, Limited-contact dynamic compression plate or Locking plate, allows a stable periprosthetic fixation with the small 3.5 screws and 4.5 screws above and below the prosthesis, respectively. This combination is a cost-effective technique to treat periprosthetic humeral fractures.

  5. Scattered radiation during fixation of hip fractures. Is distance alone enough protection?

    Science.gov (United States)

    Alonso, J A; Shaw, D L; Maxwell, A; McGill, G P; Hart, G C

    2001-08-01

    We measured the scattered radiation received by theatre staff, using high-sensitivity electronic personal dosimeters, during fixation of extracapsular fractures of the neck of the femur by dynamic hip screw. The dose received was correlated with that received by the patient, and the distance from the source of radiation. A scintillation detector and a water-filled model were used to define a map of the dose rate of scattered radiation in a standard operating theatre during surgery. Beyond two metres from the source of radiation, the scattered dose received was consistently low, while within the operating distance that received by staff was significant for both lateral and posteroanterior (PA) projections. The routine use of lead aprons outside the 2 m zone may be unnecessary. Within that zone it is recommended that lead aprons be worn and that thyroid shields are available for the surgeon and nursing assistants.

  6. 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.

  7. Study on dynamic accuracy test of high speed ball-screw based on SIEMENS S120 drive%基于西门子S120驱动的高速滚珠丝杠副动态精度测试研究

    Institute of Scientific and Technical Information of China (English)

    刘谋云; 白国振; 迟玉伦

    2012-01-01

    Designing and developing a kind of dynamic accuracy test bench of high speed ball-screw, used an automation solution method of S120 servo system and based on WinAC of PC com-munication. Set up two dynamic test systems of ball-screw thermal deformation and kinematic ac- curacy, then done tests and analyzed the data results, got the dynamic accuracy influence factors of the ball screw and proposed the corresponding measures.%设计开发了一种高速滚珠丝杠副动态精度测试试验台.试验台采用了西门子公司S120伺服驱动系统与基于PC的控制器Win AC通讯的自动化解决方案.建立了滚珠丝杠热变形与运动精度两大动态测试系统,并在自制高速滚珠丝杠副试验台上进行了测试实验,对实验数据结果进行有效的分析,得出了滚珠丝杠副动态精度的影响因素并提出相应的改进措施.

  8. The Study of Vibration Processes in Oil Flooded Screw Compressors

    Directory of Open Access Journals (Sweden)

    I. V. Filippov

    2014-01-01

    Full Text Available Vibration processes that accompany most of machines and mechanisms are of interest to the researcher, as a source of information about the technical condition and the nature of the business processes flow. Vibration-based diagnostics of oil flooded screw compressors allows us to estimate the deviation of their operation from the main mode in accordance with changing the settings of vibration processes.The oil flooded screw compressor transition from the main mode of operation to the abnormal one is accompanied by complex gas-dynamic phenomena i.e. the initial gaps and their decays. This leads to changes in the nature of vibration processes, prompting suggestions that there is a relationship to a change of vibration parameters and mode of compressor operation.Studies were conducted by combined method using an analytical calculation of the decay parameters of the initial discontinuity and an experimental one based on the measurement of acceleration on the body of the real oil flooded screw compressor. A virtually adequate reaction of the decay parameters of the initial gap and the peak values of vibration acceleration to the change of operation mode of oil flooded screw compressor has been received. The peak value of the vibration acceleration was selected by the method of Gating being time-coinciding with the beginning discharge phase of the oil flooded screw compressor, and therefore, with the decay time of the initial discontinuity.This indicates a large degree of hypothesis likelihood on an existing initial break in oil flooded screw compressor when operating in abnormal conditions. This work contains the study results of vibration processes and their relationship to the operating mode of the oil flooded screw compressor, which distinguish it from the other works studied vibration processes in reciprocating compressors. The vibration parameters control of operating oil flooded screw compressor allows us to create an automatic capacity control

  9. Comparison Between Proximal Femoral Interlocking Nail and Dynamic Condylar Screw for the Treatment of Unstable Intertrochanteric Fracture in Elderly Patients%股骨近端交锁髓内钉与动力髁螺钉治疗老年不稳定型股骨粗隆间骨折的比较

    Institute of Scientific and Technical Information of China (English)

    刘张冰; 廖乐乐

    2012-01-01

    [目的]对比股骨近端交锁髓内钉(PFN)与动力髁螺钉(DCS)治疗老年不稳定型股骨粗隆间骨折的临床疗效.[方法]选取本院收治的老年不稳定型股骨粗隆间骨折患者43例,其中 22例采用股骨近端交锁髓内钉手术内固定治疗(PFN组),21例采用动力髁螺钉手术内固定治疗(DCS组).术后随访12~26个月,对两组患者的手术情况、术后髋关节功能及并发症情况进行统计分析.[结果]两组患者手术时间比较,差异无统计学意义(P>0.05).PFN组术中出血量和引流量均明显少于DCS组(P0.05).术后1年PFN组Harris髋关节功能评分为(89.23±5.93)分,明显高于DCS组(84.09±9.38)分(P0.05).[结论]股骨近端交锁髓内钉在术中出血量、术后引流量及术后功能恢复方面均优于动力髁螺钉,是治疗老年不稳定型股骨粗隆间骨折较理想的手术方式.%[Objective] To compare the clinical efficacy of proximal femoral interlocking nail(PFN) vs dynamic condylar screw(DCS) for the treatment of unstable intertrochantcrie fracture in elderly patients. [Methods] Forty-three patients with unstable intcrtrochantcric fracture admitted to our hospital were chosen. Among them, 22 paticnts (PFN group) underwent PFN internal fixation, and 21 paticnts (DCS group) underwent DCS internal fixation. All patients were followed up for 12~26 months. The operation state, hip joint function after operation and complications in two groups were analyzed statistically. [Results] There was no significant difference in the operation time between two groups (P >0.05). The intraopcrative blood loss and drainage volume in PFN group were obviously less than those in DCS group( P0.05). Harris hip joint function score in PFN group at a year after operation was 89. 23±5. 93, which was obviously higher than that in DCS group(84. 09±9. 38) ( P0.05). [Conclusion] The intraopcrativc blood loss, postoperative drainage volume and functional recovery in PFN arc better than

  10. Posterior spinal fusion using pedicle screws.

    Science.gov (United States)

    Athanasakopoulos, Michael; Mavrogenis, Andreas F; Triantafyllopoulos, George; Koufos, Spiros; Pneumaticos, Spiros G

    2013-07-01

    Few clinical studies have reported polyetheretherketone (PEEK) rod pedicle screw spinal instrumentation systems (CD-Horizon Legacy PEEK rods; Medtronic, Minneapolis, Minnesota). This article describes a clinical series of 52 patients who underwent posterior spinal fusion using the PEEK Rod System between 2007 and 2010. Of the 52 patients, 25 had degenerative disk disease, 10 had lateral recess stenosis, 6 had degenerative spondylolisthesis, 6 had lumbar spine vertebral fracture, 4 had combined lateral recess stenosis and degenerative spondylolisthesis, and 1 had an L5 giant cell tumor. Ten patients had 1-segment fusion, 29 had 2-segment fusion, and 13 had 3-segment fusion. Mean follow-up was 3 years (range, 1.5-4 years); no patient was lost to follow-up. Clinical evaluation was performed using the Oswestry Disability Index and a low back and leg visual analog pain scale. Imaging evaluation of fusion was performed with standard and dynamic radiographs. Complications were recorded. Mean Oswestry Disability Index scores improved from 76% preoperatively (range, 52%-90%) to 48% at 6 weeks postoperatively, and to 34%, 28%, and 30% at 3, 6, and 12 months postoperatively, respectively. Mean low back and leg pain improved from 8 and 9 points preoperatively, respectively, to 6 and 5 points immediately postoperatively, respectively, and to 2 points each thereafter. Imaging union of the arthrodesis was observed in 50 (96%) patients by 1-year follow-up. Two patients sustained screw breakage: 1 had painful loss of sagittal alignment of the lumbar spine and underwent revision spinal surgery with pedicle screws and titanium rods and the other had superficial wound infection and was treated with wound dressing changes and antibiotics for 6 weeks. No adjacent segment degeneration was observed in any patient until the time of this writing. Copyright 2013, SLACK Incorporated.

  11. Corrosion of magnesium alloy AZ31 screws is dependent on the implantation site

    Energy Technology Data Exchange (ETDEWEB)

    Willbold, E. [Laboratory for Biomechanics and Biomaterials, Department of Orthopaedic Surgery, Hannover Medical School, Anna-von-Borries-Strasse 1-7, D - 30625 Hannover (Germany); Kaya, A.A. [Mugla University, Engineering Faculty, Metallurgy and Materials Engineering Department, Mugla (Turkey); Kaya, R.A. [MedicalPark Hospital, Kueltuer Sok No:1, 34160 Bahcelievler, Istanbul (Turkey); Beckmann, F. [Helmholtz-Zentrum Geesthacht, Institute of Materials Research, Max-Planck-Str.1, D - 21502 Geesthacht (Germany); Witte, F., E-mail: witte.frank@mh-hannover.de [Laboratory for Biomechanics and Biomaterials, Department of Orthopaedic Surgery, Hannover Medical School, Anna-von-Borries-Strasse 1-7, D - 30625 Hannover (Germany)

    2011-12-15

    The corrosion of biodegradable materials is a crucial issue in implant development. Among other materials, magnesium and magnesium based alloys are one of the most promising candidates. Since the corrosion of biodegradable materials depends on different physiological parameters like pH or ion concentrations, the corrosion might be different in different biological environments. To investigate this issue, we produced screws from magnesium alloy AZ31 and implanted them into the hip bone of 14 sheep. After 3 and 6 months, the screws were explanted and analyzed with synchrotron-radiation based micro-computed tomography and hard tissue histology. We found considerable differences in the corrosion behavior of the magnesium screws with respect to its original tissue location. However, we could detect a normal immunological tissue response.

  12. Does Hip Arthroscopy Have a Role in the Treatment of Developmental Hip Dysplasia?

    Science.gov (United States)

    Kirsch, Jacob M; Khan, Moin; Bedi, Asheesh

    2017-09-01

    Indications for hip arthroscopy in mildly dysplastic patients with a symptomatic hip remain controversial. This article provides a concise review of the available literature evaluating the role of hip arthroscopy in treating symptomatic dysplasia. Potential indications for hip arthroscopy in isolation are reviewed. Emerging evidence on the role of hip arthroscopy based on patient-specific pathomorphology is highlighted. Hip arthroscopy in isolation may be helpful for select dysplastic patients with dynamic impingement or microinstability. Isolated arthroscopic treatment of intra-articular pathology resulting from static overload is unlikely to be successful in the long term and may be detrimental. Arthroscopic procedures for individuals with mild dysplasia in the absence of frank instability may be effective; however, great caution should be exercised when approaching dysplastic patients with symptomatic hips. Copyright © 2017 Elsevier Inc. All rights reserved.

  13. Life Estimation of Hip Joint Prosthesis

    Science.gov (United States)

    Desai, C.; Hirani, H.; Chawla, A.

    2014-11-01

    Hip joint is one of the largest weight-bearing structures in the human body. In the event of a failure of the natural hip joint, it is replaced with an artificial hip joint, known as hip joint prosthesis. The design of hip joint prosthesis must be such so as to resist fatigue failure of hip joint stem as well as bone cement, and minimize wear caused by sliding present between its head and socket. In the present paper an attempt is made to consider both fatigue and wear effects simultaneously in estimating functional-life of the hip joint prosthesis. The finite element modeling of hip joint prosthesis using HyperMesh™ (version 9) has been reported. The static analysis (load due to the dead weight of the body) and dynamic analysis (load due to walking cycle) have been described. Fatigue life is estimated by using the S-N curve of individual materials. To account for progressive wear of hip joint prosthesis, Archard's wear law, modifications in socket geometry and dynamic analysis have been used in a sequential manner. Using such sequential programming reduction in peak stress has been observed with increase in wear. Finally life is estimated on the basis of socket wear.

  14. Hip flexor strain - aftercare

    Science.gov (United States)

    ... flexor - aftercare; Hip flexor injury - aftercare; Hip flexor tear - aftercare; Iliopsoas strain - aftercare; Strained iliopsoas muscle - aftercare; Torn iliopsoas muscle - aftercare; Psoas strain - aftercare

  15. Establishing Spacecraft′s Relative Orbit and Attitude Coupling Dynamics Model Based on Screw Theory%基于螺旋理论的航天器相对运动建模与控制

    Institute of Scientific and Technical Information of China (English)

    刘剑; 朱战霞; 马家瑨

    2013-01-01

    Considering the strong coupling between the orbit and attitude of two spacecraft in relative motion , based on the assumption of rigid body dynamics and the screw theory , we deduce and establish their orbit and attitude coupling dynamics model and analyze the orbit and attitude coupling effect .Considering that the dynamics model is strongly coupled and nonlinear , we design its nonlinear feedforward control law , which has a good control precision and stability and is suitable for the short-distance and in-orbit operations that have time constrains .We simulate the effectiveness of the orbit and attitude coupling dynamics model and the nonlinear feedforward control law ;the simu-lation results, given in Fig.1 through 6, and their analysis show preliminarily that:(1) both the relative speed and angular speed of the two spacecraft converge to zero , there being no change in their relative position and attitude and the whole control process reaching the desired value within 200 seconds; ( 2 ) the orbit and attitude coupling model we thus designed can be used for spacecraft′s short-range randezvous and the nonlinear feedforward control law can satisfy the precision requirements for in-orbit operations .%应用螺旋理论对航天器相对轨道与姿态运动进行了研究。针对航天器相对运动过程中存在的姿态轨道耦合问题:基于刚体假设,推导建立了基于螺旋对偶式的航天器姿轨耦合相对运动模型;分析给出了航天器相对运动过程中姿态轨道的耦合效应;针对所建模型的强耦合、非线性特性,在控制律设计时采用了非线性前馈控制,最后进行了数值仿真,结果表明了该模型和控制律的有效性,可为工程应用提供参考。

  16. 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.].

  17. Traumatic fracture-dislocation of the hip following rugby tackle: a case report

    Directory of Open Access Journals (Sweden)

    Venkatachalam Santosh

    2009-12-01

    Full Text Available Abstract Posterior fracture-dislocation of hip is uncommonly encountered in rugby injuries. We report such a case in an adult while playing rugby. The treating orthopaedician can be caught unaware and injuries in such sports can be potentially misdiagnosed as hip sprains. Immediate reduction of the dislocation was performed in theatres. The fracture was fixed with two lag screws and a neutralization plate. This led to early rehabilitation and speedy recovery with return to sporting activities by 12 months.

  18. Hip fracture fixation in a patient with below-knee amputation presents a surgical dilemma: a case report

    Directory of Open Access Journals (Sweden)

    Rethnam Ulfin

    2008-09-01

    Full Text Available Abstract Introduction Hip fracture fixation surgery in patients with below-knee amputations poses a challenging problem to the surgeon in terms of obtaining traction for reduction of the fracture. The absence of the foot and part of the leg in these patients makes positioning on the fracture table difficult. We highlight this difficult problem and suggest techniques to overcome it. Case presentation A 73-year-old man with bilateral below-knee amputations presented with a history of fall. Radiographs revealed an inter-trochanteric fracture of the femur. A dynamic hip screw fixation was planned for the fracture but the dilemma was on how to position the patient on the fracture table for the surgery. Special attention was needed in positioning the patient and in surgical fixation of the fracture. Conclusion Hip fracture fixation in patients with below-knee amputations poses a special problem in positioning for fracture reduction and fixation. In this case report, we share our experience and suggest techniques to use when encountering this difficult problem.

  19. 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.

  20. Ultrasound: Infant Hip

    Science.gov (United States)

    ... ultrasound when they suspect a problem called developmental dysplasia of the hip (DDH) . DDH is a hip deformity that can ... THIS TOPIC X-Ray Exam: Leg Length Developmental Dysplasia of the Hip X-Ray Exam: Hip Contact Us Print Resources ...

  1. Secondary capsular laxity of the hip.

    Science.gov (United States)

    Blakey, Caroline M; Field, Michael H; Singh, Parminder J; Tayar, Rene; Field, Richard E

    2010-01-01

    We describe a hip condition with a recognisable pattern of clinical signs and radiological findings thought to result from chronic capsular injury. Between June 2006 and October 2009, ten patients (11 hips), four men and six women, were identified with an abnormality of external rotation at the hip joint. A detailed history and clinical examination was undertaken for each patient. Dynamic magnetic resonance imaging of symptomatic and control hips were evaluated for bony and soft tissue appearances. The relative positions of the femoral head and the acetabulum were assessed through a range of hip rotation. In affected hips, a loss of normal log roll recoil was observed. Three distortions of the iliofemoral ligament were identified on axial MR images; thinning at the lateral insertion of the ligament, attenuation of the iliofemoral ligament most noticeably on maximum external rotation (60º) and the appearance of laxity despite full external rotation. Stability of the hip is dependent on the interaction of bony and soft tissue structures. Hip instability is recognised in dysplasia and is known to lead to premature degeneration of the joint. Chronic capsular injury may destabilise previously asymptomatic hips with subsequent development of pain in young, active patients.

  2. The effect of hydroxyapatite coated screw in the lateral fragility fractures of the femur. A prospective randomized clinical study.

    Science.gov (United States)

    Pesce, V; Maccagnano, G; Vicenti, G; Notarnicola, A; Moretti, L; Tafuri, S; Vanni, D; Salini, V; Moretti, B

    2014-01-01

    Due to a growing numbers of lateral fragility fractures of the femur and their high social costs the need to work out an effective strategy in order to find a better solution for these patients is warranted. From January 2010 to July 2011, we carried out a prospective randomized clinical study comparing the results of patients with femoral lateral fractures treated by nail and cephalic hydroxyapatite coated screws (study group including 27 patients) compared to the patients with the same fractures treated with nail and head standard screws (control group including 27 patients). We defined the two parts of the femoral neck as ROI 1 (under the head screw) and ROI 2 (above the femoral screw) on the AP view. The bone density of the two areas was calculated using DEXA at T0 (1st day post-surgery), at T1 (40th day post-surgery), at T2 (3 months later), at T3 (1 year later). The clinical-radiography evaluations were based on the Harris Hip Score (HHS), ADL test and x-ray views of the hip. As far as the bone mineral density average of ROI 1 and ROI 2 is concerned, we found a significant statistical increase at T1 and T3 in the study group, while it was not significant in the control group. We could account for this data through the higher mechanical stability of hydroxyapatite coated screws than standard screws. In fact, this material was responsible for improved implant osteointegration. Thanks to a 1 year follow-up we were able to demonstrate the implant utility associated with augmentation and the importance of densitometry exams such as easily repeatable and low cost diagnostics to prevent the onset of complications linked to screw loosening.

  3. 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

  4. 多运动体航天器旋量理论动力学建模与滑模控制%Dynamic modeling and sliding mode control of multi-moving-body spacecraft using screw theory

    Institute of Scientific and Technical Information of China (English)

    许晨; 陆宇平; 刘燕斌; 徐志晖

    2012-01-01

    There exists intense coupling in the movement of all parts of multi-moving-body spacecraft, which increases the difficulty of dynamic modeling and control. The versatile attitude dynamic model of multi-moving-body spacecraft for any tree structure of open-loop is constructed by using both screw theory and Kane method, which simplifies the analysis of system kinematics, reduces the workload of calculation and makes the process clearer. Aiming at the features of the system that is strong coupled and high nonlinearity, a non-singular terminal sliding mode controller based on inverse system way is designed for all parts of system attitude maneuvering together. Firstly: an α order inverse system is designed and is integrated with the original system to constitute the pseudo linear system to finish the process of accurate feedback linearization. Secondly, a non-singular terminal sliding mode controller is designed for attitude maneuver, so as to guarantee the state error of the system to converge to zero in limited time. Simulation results show the effectiveness of the proposed method.%多运动体航天器系统各部分运动存在强烈耦合,这增加了动力学建模与控制难度.应用旋量理论与凯恩方程建立开环树状拓扑构型多运动体航天器通用的姿态动力学模型,有效简化系统运动学分析,计算量小,步骤清晰.针对系统强耦合,高度非线性的特点,设计基于逆系统的非奇异最终滑模控制器,完成系统各运动体姿态机动控制.首先,针对动力学方程设计α阶逆系统与原系统组成伪线性系统,完成精确反馈线性化的过程.然后,应用非奇异最终滑模控制器实现系统姿态机动控制,保证系统状态误差在有限时间内收敛到零.算例仿真结果验证了方法的有效性.

  5. Biomechanical Analysis of Latarjet Screw Fixation: Comparison of Screw Types and Fixation Methods.

    Science.gov (United States)

    Shin, Jason J; Hamamoto, Jason T; Leroux, Timothy S; Saccomanno, Maristella F; Jain, Akshay; Khair, Mahmoud M; Mellano, Christen R; Shewman, Elizabeth F; Nicholson, Gregory P; Romeo, Anthony A; Cole, Brian J; Verma, Nikhil N

    2017-09-01

    To compare the initial fixation stability, failure strength, and mode of failure of 5 different screw types and fixation methods commonly used for the classic Latarjet procedure. Thirty-five fresh-frozen cadaveric shoulder specimens were allocated into 5 groups. A 25% anteroinferior glenoid defect was created, and a classic Latarjet coracoid transfer procedure was performed. All grafts were fixed with 2 screws, differing by screw type and/or fixation method. The groups included partially threaded solid 4.0-mm cancellous screws with bicortical fixation, partially threaded solid 4.0-mm cancellous screws with unicortical fixation, fully threaded solid 3.5-mm cortical screws with bicortical fixation, partially threaded cannulated 4.0-mm cancellous screws with bicortical fixation, and partially threaded cannulated 4.0-mm captured screws with bicortical fixation. All screws were stainless steel. Outcomes included cyclic creep and secant stiffness during cyclic loading, as well as load and work to failure during the failure test. Intergroup comparisons were made by a 1-way analysis of variance. There were no significant differences among different screw types or fixation methods in cyclic creep or secant stiffness after cyclic loading or in load to failure or work to failure during the failure test. Post-failure radiographs showed evidence of screw bending in only 1 specimen that underwent the Latarjet procedure with partially threaded solid cancellous screws with bicortical fixation. The mode of failure for all specimens analyzed was screw cutout. In this biomechanical study, screw type and fixation method did not significantly influence biomechanical performance in a classic Latarjet procedure. When performing this procedure, surgeons may continue to select the screw type and method of fixation (unicortical or bicortical) based on preference; however, further studies are required to determine the optimal method of treatment. Surgeons may choose the screw type and

  6. 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.

  7. Complications after Hip Arthroscopy

    Science.gov (United States)

    Larson, Christopher M.; Clohisy, John C.; Beaule, Paul; Kelly, Bryan T.; Giveans, Russell; Stone, Rebecca M.; Samuelson, Kathryn M.

    2013-01-01

    Objectives: There is very little published literature looking at comprehensive complication rates after hip arthroscopy with current techniques and indications. Methods: Between 01/2011 and 11/2012, 1,026 consecutive hips (507 males, 519 females) with a mean age of 31.2 years (range 12 - 73) underwent hip arthroscopy at three institutions. The diagnosis, demographic information, and procedures were recorded, and a validated complications grading classification for hip joint surgery (Clavian classification) was utilized for all patients prospectively. Results: There were 951 primary hip arthroscopies and 75 revision hip arthroscopies. Arthroscopy was performed for FAI in 936 hips (91.2%), and 760 hips (74.1%) had a labral repair and 229 hips (22.3%) had a labral debridement. The most common event (18.7% of hips) noted was post-operative sensory disturbance adjacent to the portals or involving the distal anterolateral thigh consistent with LFC nerve disturbance. This was typically not noticed by patients and found on physical examination and only persisted beyond 6 months in 7 hips (0.7%). Iatrogenic chondral injury was noted for 20 hips (1.9%), iatrogenic labral puncture in 11 hips (1.1%), superficial portal infection in 6 hips (0.6%), sensory deficit about the foot in 9 hips (0.9%), deep venous thrombosis in 3 hips (0.3%), pulminary embolism in 1 hip (0.1%), pulmonary edema in 1 hip (0.1%), wound hematoma in 2 hips (0.2%), perineal numbness (pudendal nerve) in 9 hips (0.9%), heterotopic ossification in 4 hips (0.4%), reflex sympathetic dystrophy in 1 hip (0.1%) and wound/skin (traction) dehiscence in 1 hips (0.1%). There were no femoral neck fractures, iatrogenic instability, AVN, or extra-abdominal fluid extravasation in this cohort. The overall complication rate not including temporary periportal and thigh numbness (sequalae) was 6.9% (71 hips). Overall 88.7% had a grade 1, 5.6% Grade 2, 4.2% grade 3, and 1.4% grade 4 complication. There was no difference in the

  8. Hominin Hip Biomechanics: Changing Perspectives.

    Science.gov (United States)

    Warrener, Anna G

    2017-05-01

    The shape of the human pelvis reflects the unique demands placed on the hip abductor muscles (gluteus medius and gluteus minimus), which stabilize the body in the frontal plane during bipedal locomotion. This morphological shift occurred early in hominin evolution, yet important shape differences between hominin species have led to significant disagreement about abductor function and locomotor capability in these extinct taxa. A static biomechanical model that relies on a close association between skeletal measurements of the pelvis and femur has traditionally been used to reconstruct hip biomechanics in these species. However, experimental biomechanical approaches have highlighted the dynamic nature of mediolateral balance in walking and running, challenging the assumptions of the static hip model. This article reviews traditional approaches for understanding hip abductor function, shows how they have been applied to the fossil hominin record, and discusses new techniques that integrate the dynamic nature of mediolateral balance during human locomotion. Anat Rec, 300:932-945, 2017. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

  9. Static and Dynamic Mechanics Analysis on Artificial Hip Joints with Different Interface Designs by the Finite Element Method

    Institute of Scientific and Technical Information of China (English)

    Hai-bo Jiang

    2007-01-01

    Four different structural models of artificial joints were developed and the finite element method (FEM) was employed to investigate their mechanical characteristics under static and dynamic conditions. The materials used in the FEM calculation were ultra-high molecular weight polyethylene (UHMWPE), 316L stainless steel, CoCrMo alloy and Ti6A14V alloy. The stress distribution, strain, and elastic deformation under static and dynamic conditions were obtained. Analysis and comparison of the calculation results of different models were conducted. It is shown that with the same parameters the model of a metallic femur head covered with an artificial cartilage layer is more similar to the structure of the natural human joint and its mechanical characteristics are the best of the four models.

  10. 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.

  11. Biopolymer augmentation of the lag screw in the treatment of femoral neck fractures - a biomechanical in-vitro study

    Directory of Open Access Journals (Sweden)

    Paech A

    2010-04-01

    Full Text Available Abstract The cut-out of the sliding screw is one of the most common complications in the treatment of intertrochanteric fractures. The reasons for the cut-out are: a suboptimal position of the hip-screw in the femoral head, the type of fracture and poor bone quality. The aim of this study was to reproduce the cut-out event biomechanically and to evaluate the possible prevention of this event by the use of a biopolymer augmentation of the hip screw. Concerning the density and compression force of osteoporotic femoral bone polyurethane foam according to the terms of the Association for Standard Testing Material (ASTMF 1839-97 was used as test material. The polyurethane foam Lumoltan 200 with a compression force of 3.3 Mpa and a density of 0.192 g/cm3 was used to reproduce the osteoporotic bone of the femoral fragment (density 12 lbm/ft3. A cylinder of 50 mm of length and 50 mm of width was produced by a rotary splint raising procedure with planar contact. The axial load of the system was performed by a hydraulic force cylinder of a universal test machine type Zwick 1455, Ulm, Germany. The CCD-angle of the used TGN-System was preset at 130 degrees. The migration pattern of the hip screw in the polyurethane foam was measured and expressed as a curve of the distance in millimeter [mm] against the applied load in Newton [N] up to the cut-out point. During the tests the implants reached a critical changing point from stable to unstable with an increased load progression of steps of 50 Newton. This unstable point was characterized by an increased migration speed in millimeters and higher descending gradient in the migration curve. This peak of the migration curve served as an indicator for the change of the hip screw position in the simulated bone material. The applied load in the non-augmented implant showed that in this group for a density degree of 12 (0,192 g/cm3 the mean force at the failure point was 1431 Newton (± 52 Newton. In the augmented

  12. 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.

  13. Groin and hip quandaries

    African Journals Online (AJOL)

    specialist opinions and four different surgical procedures. One needs sound ... of pain. The two joints in the pelvis should be emphasised – the hip joint and the pubic .... intervention aimed at improving hip kinematics would be effective in.

  14. Hip fracture - discharge

    Science.gov (United States)

    ... this page: //medlineplus.gov/ency/patientinstructions/000168.htm Hip fracture - discharge To use the sharing features on this page, please enable JavaScript. Hip fracture surgery is done to repair a break in ...

  15. Hip fracture surgery

    Science.gov (United States)

    ... neck fracture repair; Trochanteric fracture repair; Hip pinning surgery; Osteoarthritis - hip ... You may receive general anesthesia for this surgery. This means you ... spinal anesthesia . With this kind of anesthesia, medicine is ...

  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 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.

  18. 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.

  19. Treatment options for unstable trochanteric fractures: Screw or helical proximal femoral nail

    Institute of Scientific and Technical Information of China (English)

    Jeetendra Bajpai; Rajesh Maheshwari; Akansha Bajpai; Sumit Saini

    2015-01-01

    Purpose: To compare treatment outcome of screw proximal femoral nail (PFN) system with that of a helical PFN.Methods: The study included 77 patients with closed unstable intertrochanteric fracture classified as AO 31A2 & 31A3, between June 2008 to August 2011.Inclusion criteria were: all mature skeletons above 50 years of age;closed unstable trochanteric fracture classified as AO 31A2 & A3.Exclusion criteria were: immature skeleton, pathological fracture of any cause other than osteoporosis, inability to walk independently prior to injury.Patients were randomized to 2 treatment groups based on admission sequence.Forty patients were treated with screw PFN and thirty seven were treated with helical PFN.Results: Both groups were similar in respect of time of surgery, blood loss and functional assessment and duration of hospitalization.In screw PFN group 2 patients had superficial wound infection, 1 patient had persistent hip pain and 1 patient had shortening >1 cm but <2 cm, while in helical PFN group 1 patient had superficial wound infection.Conclusion: Both screw and helical PFN are very effective implants in osteoporotic and unstable trochanteric fractures even in Indian patients where the bones are narrow and neck diameter is small.It is an implant of choice for osteoporotic and unstable trochanteric fractures.

  20. Radiation exposure from fluoroscopy during fixation of hip fracture and fracture of ankle: Effect of surgical experience

    Directory of Open Access Journals (Sweden)

    Botchu Rajesh

    2008-01-01

    Full Text Available Background: Over the years, there has been a tremendous increase in the use of fluoroscopy in orthopaedics. The risk of contracting cancer is significantly higher for an orthopedic surgeon. Hip and spine surgeries account for 99% of the total radiation dose. The amount of radiation to patients and operating surgeon depends on the position of the patient and the type of protection used during the surgery. A retrospective study to assess the influence of the radiation exposure of the operating surgeon during fluoroscopically assisted fixation of fractures of neck of femur (dynamic hip screw and ankle (Weber B was performed at a district general hospital in the United Kingdom. Materials and Methods: Sixty patients with undisplaced intertrochanteric fracture were included in the hip group, and 60 patients with isolated fracture of lateral malleolus without communition were included in the ankle group. The hip and ankle groups were further divided into subgroups of 20 patients each depending on the operative experience of the operating surgeon. All patients had fluoroscopically assisted fixation of fracture by the same approach and technique. The radiation dose and screening time of each group were recorded and analyzed. Results: The radiation dose and screening time during fluoroscopically assisted fixation of fracture neck of femur were significantly high with surgeons and trainees with less than 3 years of surgical experience in comparison with surgeons with more than 10 years of experience. The radiation dose and screening time during fluoroscopically assisted fixation of Weber B fracture of ankle were relatively independent of operating surgeon′s surgical experience. Conclusion: The experience of operating surgeon is one of the important factors affecting screening time and radiation dose during fluoroscopically assisted fixation of fracture neck of femur. The use of snapshot pulsed fluoroscopy and involvement of senior surgeons could

  1. The Hip Restoration Algorithm

    Science.gov (United States)

    Stubbs, Allston Julius; Atilla, Halis Atil

    2016-01-01

    Summary Background Despite the rapid advancement of imaging and arthroscopic techniques about the hip joint, missed diagnoses are still common. As a deep joint and compared to the shoulder and knee joints, localization of hip symptoms is difficult. Hip pathology is not easily isolated and is often related to intra and extra-articular abnormalities. In light of these diagnostic challenges, we recommend an algorithmic approach to effectively diagnoses and treat hip pain. Methods In this review, hip pain is evaluated from diagnosis to treatment in a clear decision model. First we discuss emergency hip situations followed by the differentiation of intra and extra-articular causes of the hip pain. We differentiate the intra-articular hip as arthritic and non-arthritic and extra-articular pain as surrounding or remote tissue generated. Further, extra-articular hip pain is evaluated according to pain location. Finally we summarize the surgical treatment approach with an algorithmic diagram. Conclusion Diagnosis of hip pathology is difficult because the etiologies of pain may be various. An algorithmic approach to hip restoration from diagnosis to rehabilitation is crucial to successfully identify and manage hip pathologies. Level of evidence: V. PMID:28066734

  2. Hip Injuries and Disorders

    Science.gov (United States)

    ... problems. Osteoarthritis can cause pain and limited motion. Osteoporosis of the hip causes weak bones that break easily. Both of these are common in older people. Treatment for hip disorders may include rest, medicines, physical therapy, or surgery, including hip replacement.

  3. Ultrasound: Infant Hip

    Science.gov (United States)

    ... Old Feeding Your 1- to 2-Year-Old Ultrasound: Infant Hip KidsHealth > For Parents > Ultrasound: Infant Hip A A A What's in this ... en los lactantes What It Is A hip ultrasound is a safe and painless test that uses ...

  4. Hip Problems in Infants

    Science.gov (United States)

    ... hip problems later in life? ResourcesScreening for Developmental Dysplasia of the Hip by LM French, M.D., and FR Dietz, ... 2014 Categories: Family Health, Infants and ToddlersTags: dislocation, dysplasia, external, femoral, hip, infants, internal, problems, socket, torsion Family Health, Infants ...

  5. Imaging findings in external snapping hip syndrome

    Energy Technology Data Exchange (ETDEWEB)

    Krishnamurthy, Ganesh; Connolly, Bairbre L. [The Hospital for Sick Children, Image Guided Therapy, Diagnostic Imaging, Toronto (Canada); Narayanan, Unni [The Hospital for Sick Children, Pediatric Orthopedic Surgery, Toronto (Canada); Babyn, Paul S. [The Hospital for Sick Children, Diagnostic Imaging, Toronto (Canada)

    2007-12-15

    We describe a case of external snapping hip diagnosed by dynamic sonography. The case prompted us to retrospectively review the imaging findings of children who clinically had presented with snapping hip. From this review we identified the features on MRI and CT of either thickening of the iliotibial band or thickening of the anterior edge of the gluteus maximus muscle as the cause of snapping and atrophy of the bulk of gluteus maximus muscle as an important secondary sign associated with snapping. (orig.)

  6. The Axial Nonlinear Vibration Analysis of Ball-screw about Machine Tool Feeding System

    Institute of Scientific and Technical Information of China (English)

    ZENG Hao-ran; LIU Nian-cong; YANG Jia-rui; CHEN Jian-long; GENG Wei-tao

    2016-01-01

    The forced state of the ball⁃screw of machine tool feeding system is analyzed. The ball⁃screw is simplified as Timoshenko beam and the differential equation of motion for the ball⁃screw is built. To obtain the axial vibration equation, the differential equation of motion is simplified using the assumed mode method. Axial vibration equation is in form of Duffing equation and has the characteristics of nonlinearity. The numerical simulation of Duffing equation is proceeded by MATLAB/Simulink. The effect of screw length, exciting force and damping coefficient are researched, and the axial vibration phase track diagram and Poincare section are obtained. The stability and period of the axial vibration are analyzed. The limit cycle of phase track diagram is enclosed. Axial vibration has two type⁃center singularity distributions on both sides of the origin. The singularity attracts vibration to reach a stable state, and Poincare section shows that axial vibration appears chaotic motion and quasi periodic motion or periodic motion. Singularity position changes with the vibration system parameters, while the distribution doesn′t change. The period of the vibration is enhanced with increasing frequency and damping coefficient. Test of the feeding system ball⁃screw axial vibration exists chaos movement. This paper provides a certain theoretical basis for the dynamic characteristic analysis of machine feeding system ball⁃screw and optimization of structural parameters.

  7. Numerical and Experimental Investigation of Pressure Losses at Suction of a Twin Screw Compressor

    Science.gov (United States)

    Arjeneh, M.; Kovacevic, A.; Rane, S.; Manolis, M.; Stosic, N.

    2015-08-01

    Rotary twin screw machines are used in the wide range of industrial applications and are capable of handling single and multiphase fluids as compressors, expanders and pumps. Concentration of liquid in the inlet flow can influence the performance of the machine significantly. Characteristics of the multiphase flow at the suction of a screw compressor depend on the local flow velocities and concentration. Local flow velocity measurements inside the screw compressors are difficult to obtain. However other flow properties such as local pressures are easier to attain. It is therefore useful to carry out experiments with local pressure variations in the suction which can be used to validate the 3D numerical Computational Fluid Dynamic (CFD) models that could help in studying the single and multiphase flow behaviour in screw compressors. This paper presents experimental efforts to measure the local pressure losses inside the suction plenum of the screw compressor. Pressure variations are measured at 23 locations in the suction port at various operating conditions and compared with 3D CFD model. The grid generator SCORGTM was used for generating numerical mesh of rotors. The flow calculations were carried out using commercial 3D solver ANSYS CFX. It was found that the local pressure changes predicted by the CFD model are in the good agreement with measured pressures. This validated the use of CFD for modelling of the single phase flows in suction of screw machines.

  8. Analysis of human mandibular mechanics based on screw theory and in vivo data.

    Science.gov (United States)

    Gal, J A; Gallo, L M; Palla, S; Murray, G; Klineberg, I

    2004-09-01

    In this paper the mechanics of human mandibular function is described in terms of the associated screws. The two distinct, yet related features of jaw mechanics, involving the motion itself as well as the forces, are both functions of the anatomical constraints, namely the contact areas that exist within the temporomandibular joint, and the forces of the muscles and tendons that allow motion to occur. The relationships that exist between these two aspects of jaw-motion are identified in this paper showing that muscle forces can be uniquely represented in terms of the action screw. This new approach to analyzing the mechanics of jaw-motion also incorporates the previously studied motion screw or helical axis. A consistent dynamic model is formulated where the action screw is used to represent the action of the closing muscle forces while the moment arms of the muscle forces are determined about the motion screw representing mandibular kinematics. The action screw formulation is verified using in vivo motion data and MR image information for a single asymptomatic subject. The results confirm the feasibility of the method and its application in dental research. A general increase in the mechanical advantage of most muscles, in the distance between action and motion screws as well as in the expended energy towards the end of the jaw-closing phase was observed. Asymmetries in the distribution of muscle force magnitudes appeared to influence the resultant force and moment of the action screw but had little effect on its spatial location. The method presented is intended to facilitate understanding of mandibular function and dysfunction.

  9. HIP-HOP教室

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    从现在开始我们要为了Hip-hop而奋斗,使身边的人改变对Hip-hop文化的看法,让他们知道什么是真正的Hip-hop,更要让大家学会怎样用肢体去表达,Yo,在这里,永远不会出现半吊子的Hip-hop,因为我们都是来真的,Yo,来真的,因为我要将Hip-hop发扬到底,Yeah!

  10. Hip arthroscopy in the setting of hip dysplasia

    OpenAIRE

    Yeung, M; Kowalczuk, M.; Simunovic, N.; Ayeni, O. R.

    2016-01-01

    Objective Hip arthroscopy in the setting of hip dysplasia is controversial in the orthopaedic community, as the outcome literature has been variable and inconclusive. We hypothesise that outcomes of hip arthroscopy may be diminished in the setting of hip dysplasia, but outcomes may be acceptable in milder or borderline cases of hip dysplasia. Methods A systematic search was performed in duplicate for studies investigating the outcome of hip arthroscopy in the setting of hip dysplasia up to Ju...

  11. Combining of small fragment screws and large fragment plates for open reduction and internal fixation of periprosthetic humeral fractures

    Directory of Open Access Journals (Sweden)

    Dominik Seybold

    2011-01-01

    Full Text Available Operative treatment of periprosthetic humeral fractures in elderly patients with osteoporotic bone requires a stable fixations technique. The combination of 3.5 cortical screws with washers in a 4.5 Arbeitsgemeinschaft fόr Osteosynthesefragen, Limited-contact dynamic compression plate or Locking plate, allows a stable periprosthetic fixation with the small 3.5 screws and 4.5 screws above and below the prosthesis, respectively. This combination is a cost-effective technique to treat periprosthetic humeral fractures.

  12. 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

  13. Vertical-Screw-Auger Conveyer Feeder

    Science.gov (United States)

    Walton, Otis (Inventor); Vollmer, Hubert J. (Inventor)

    2016-01-01

    A conical feeder is attached to a vertically conveying screw auger. The feeder is equipped with scoops and rotated from the surface to force-feed regolith the auger. Additional scoops are possible by adding a cylindrical section above the conical funnel section. Such then allows the unit to collect material from swaths larger in diameter than the enclosing casing pipe of the screw auger. A third element includes a flexible screw auger. All three can be used in combination in microgravity and zero atmosphere environments to drill and recover a wide area of subsurface regolith and entrained volatiles through a single access point on the surface.

  14. 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.

  15. 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...

  16. [Irritation of the iliopsoas tendon after total hip arthroplasty].

    Science.gov (United States)

    Hessmann, M H; Hübschle, L; Tannast, M; Siebenrock, K A; Ganz, R

    2007-08-01

    Chronic irritation of the iliopsoas tendon is a rare cause of persistent pain after total joint replacement of the hip. In the majority of cases, pain results from a mechanical conflict between the iliopsoas tendon and the anterior edge of the acetabular cup after total hip arthroplasty. Pain can be reproduced by active flexion of the hip and by active raising of the straightened leg. In addition, painful leg raising against resistance and passive hyperextension are suggestive of an irritation of the iliopsoas tendon. Symptoms evolve from a mechanical irritation of the iliopsoas tendon and an oversized or retroverted acetabular cup, screws penetrating into the inner aspect of the ilium, or from bone cement protruding beyond the anterior acetabular rim. The diagnosis may be assumed on conventional radiographs and confirmed by CT scans. Fifteen patients with psoas irritation after total hip replacement are reported on. Eleven patients were treated surgically. The acetabular cup was revised and reoriented with more anteversion in six patients, isolated screws penetrating into the tendon were cut and leveled in three patients, and prominent bone cement in conflict with the tendon was resected once. A partial release of the iliopsoas tendon only was performed in another patient. Follow-up examination (range: 11-89 months) revealed that nine patients were free of pain and two patient had mild residual complaints. Psoas irritation in combination with total hip replacement can be prevented by a correct surgical technique, especially with proper selection of the cup size and insertion of the acetabular cup avoiding a rim position exceeding the level of the anterior acetabular rim.

  17. Imaging of hip arthroplasty

    Energy Technology Data Exchange (ETDEWEB)

    Miller, Theodore T., E-mail: millertt@hss.edu [Department of Radiology and Imaging, Hospital for Special Surgery, 535 E. 70th Street, New York, NY 10021 (United States)

    2012-12-15

    The imaging evaluation of the prosthetic hip begins with radiography, but arthrography, aspiration, scintigraphy, sonography, CT and MR imaging all have roles in the evaluation of the painful prosthesis. This article will review the appearance of normal hip arthroplasty including hemiarthroplasty, total arthroplasty, and hip resurfacing, as well as the appearances of potential complications such as aseptic loosening and osteolysis, dislocation, infection, periprosthetic fracture, hardware failure, and soft tissue abnormalities.

  18. Hip resurfacing arthroplasty

    OpenAIRE

    2010-01-01

    Background and purpose Hip resurfacing arthroplasty is claimed to allow higher activity levels and to give better quality of life than total hip arthroplasty. In this literature review, we assessed the therapeutic value of hip resurfacing arthroplasty as measured by functional outcome. Methods An extensive literature search was performed using the PubMed, Embase, and Cochrane databases. Results 9 patient series, 1 case-control study, and 1 randomized controlled trial (RCT) were included. Clin...

  19. 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.

  20. Fracture After Total Hip Replacement

    Science.gov (United States)

    ... osteolysis. Symptoms The most common symptoms of periprosthetic hip fracture include: • Pain around the hip or thigh • Swelling ... o en very painful, someone with a periprosthetic hip fracture will most likely go directly to the emergency ...

  1. Hip Fractures among Older Adults

    Science.gov (United States)

    ... online training for health care providers. Learn More Hip Fractures Among Older Adults Recommend on Facebook Tweet Share ... get older. What You Can Do to Prevent Hip Fractures You can prevent hip fractures by taking steps ...

  2. Hip dysplasia and the performing arts: is there a correlation?

    Science.gov (United States)

    Turner, Robert; O'Sullivan, Eilish; Edelstein, Jaime

    2012-03-01

    Dancers frequently present with hip pain. The etiology of this pathology has not been clearly identified from an anatomical perspective. Structural variations including hip dysplasia and dynamic variables from the foot to the pelvis will be discussed. Understanding the etiology as a structural entity, neuromuscular entity or a combination of the two, allows for a successful rehabilitative process and a successful return to dance. This article describes the possible correlation between hip dysplasia and hip pain in the dancer, the relationship of dance postures to the kinematic chain and outlines possible treatment strategies for management.

  3. 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

  4. CONSERVATIVE TREATMENT OF HIP DYSPLASIA

    OpenAIRE

    Михаил Михайлович Камоско; Махмуд Станиславович Познович

    2014-01-01

    Hip dysplasia in children is the subject of careful study by specialists both in our country and abroad. There are three basic variants of hip dysplasia: congenital acetabular dysplasia, congenital subluxation of the hip and congenital dislocation of the hip. However, treatment of congenital dislocation of the hip, which is the most severe form of hip dysplasia in children, currently remains one of the topical problems of children’s orthopedics, despite the significant achievements of modern ...

  5. 股骨近端骨折应用髁动力加压板在术后早期非负重功能训练中的作用%The function of the dynamic condylar screw in the early post operational non loading functional exercises for the proximal fracture of femur

    Institute of Scientific and Technical Information of China (English)

    茅治湘; 王鸥; 王全明

    2002-01-01

    @@ Background: Recently, more and more high energy injuries appeared, the proximal fracture of femur was no longer the simple fracture of btween femur tuberosity or below femur tuberosity.It is often accompanied with fracture of the upper femur.For biodynamic and anatomical reasons, such fractures are difficult to deal with,there is often great pressing stress in the inner corner of the neck of the femur, which caused great extending stress in the outer surface.Such fractures are unsteady for any of such stresses would cause the inner immobilization to fail,while to apply the dynamic condylar screw(DCS) on such fractures may got satisfactory results and it provided favorable conditions for the early post operational non loading walking exercises. Objective: To discuss the treating value of DCS in the proximal fracture of the femur.

  6. 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

  7. 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.

  8. Design of Nano Screw Pump for Water Transport and its Mechanisms

    Science.gov (United States)

    Wang, Liya; Wu, Hengan; Wang, Fengchao

    2017-02-01

    Nanopumps conducting fluids through nanochannels have attracted considerable interest for their potential applications in nanofiltration, water desalination and drug delivery. Here, we demonstrate by molecular dynamics (MD) simulations that a nano screw pump is designed with helical nanowires embedded in a nanochannel, which can be used to drive unidirectional water flow. Such helical nanowires have been successfully synthesized in many experiments. By investigating the water transport mechanism through nano screw pumps with different configuration parameters, three transport modes were observed: cluster-by-cluster, pseudo-continuous, and linear-continuous, in which the water flux increases linearly with the rotating speed. The influences of the nanowires’ surface energy and the screw’s diameter on water transport were also investigated. Results showed that the water flux rate increases as the decreasing wettability of helical nanowires. The deviation in water flux in screw pumps with smaller radius is attributed to the weak hydrogen bonding due to space confinement and the hydrophobic blade. Moreover, we also proposed that such screw pumps with appropriate diameter and screw pitch can be used for water desalination. The study provides an insight into the design of multifunctional nanodevices for not only water transport but water desalination in practical applications.

  9. Design of Nano Screw Pump for Water Transport and its Mechanisms

    Science.gov (United States)

    Wang, LiYa; Wu, HengAn; Wang, FengChao

    2017-01-01

    Nanopumps conducting fluids through nanochannels have attracted considerable interest for their potential applications in nanofiltration, water desalination and drug delivery. Here, we demonstrate by molecular dynamics (MD) simulations that a nano screw pump is designed with helical nanowires embedded in a nanochannel, which can be used to drive unidirectional water flow. Such helical nanowires have been successfully synthesized in many experiments. By investigating the water transport mechanism through nano screw pumps with different configuration parameters, three transport modes were observed: cluster-by-cluster, pseudo-continuous, and linear-continuous, in which the water flux increases linearly with the rotating speed. The influences of the nanowires’ surface energy and the screw’s diameter on water transport were also investigated. Results showed that the water flux rate increases as the decreasing wettability of helical nanowires. The deviation in water flux in screw pumps with smaller radius is attributed to the weak hydrogen bonding due to space confinement and the hydrophobic blade. Moreover, we also proposed that such screw pumps with appropriate diameter and screw pitch can be used for water desalination. The study provides an insight into the design of multifunctional nanodevices for not only water transport but water desalination in practical applications. PMID:28155898

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

    Directory of Open Access Journals (Sweden)

    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

  11. Anatomical measurement of the posterior structure of lumbar spine and design of the lumber laminar screw dynamic system%腰椎棘板的应用解剖研究与动态内固定系统的研制

    Institute of Scientific and Technical Information of China (English)

    袁健东; 吴云刚; 刘彩龙; 陈鑫

    2013-01-01

    目的 通过获取骨骼标本中腰椎后柱结构的相关解剖参数以及健康人腰椎后柱的三维构象样本数据,设计腰椎棘板螺钉动态内固定系统.方法 对20具L3~S1段骨骼标本行层次解剖,使用游标卡尺测量椎板区域的厚度以获取腰椎棘板的相关解剖参数;另对20名健康成人腰椎的L3~S1段行三维CT重建扫描,以获取腰椎后部结构三维空间构象样本数据.结果 通过解剖观察与测量,棘板螺钉固定置钉区域拟设定在腰椎椎板内侧的中1/3处,椎板L3~4段厚度(6.6±0.9) mm,L5~S1段厚度(6.0±0.6)mm.长度6.5~8.0 mm的棘板螺钉符合双侧皮质骨螺钉固定的要求.结论 可选择下腰椎棘突椎板区域为双侧皮质骨螺钉固定区域,椎板螺钉长度6.5~8.0 mm即可.%Objective To determine the lumbar anatomical structure parameters of the lumbar spine posterior column and its sample data of three-dimensional conformation,and based on these data to design the lumber laminar screw dynamic fixation system.Methods 20 human L3 ~ S1 bone specimens,the thickness of the lumber laminar region were measured to obtain the normal anatomical parameters of the lumbar laminar.And 20 healthy lumbar vertebrae L3-S1 for three-dimensional reconstruction were detected by CT scan,which could obtain the structure data of the normal lumbar posterior three-dimensional conformation,and to obtain conformational sample data of three-dimensional space of the posterior structure.Results Lumbar lamina medial 1/3 could serve as a spine laminar screw setting area by anatomical observations and measurements.Lamina thickness of L3-4 on average (6.6 ±0.9) mm,L5 ~ S1average (6.0 ± 0.6) mm.Lumber laminar screw length 6.5 ~ 8.0mm could meet the requirements of bilateral cortical fixation.Conclusion Lower lumbar spinal lamina area can serve as the region to fix the bilateral cortical bone screw,and the optimal length of the laminar screw is 6.5 ~ 8.0rmm.

  12. Hip joint pathology

    DEFF Research Database (Denmark)

    Tijssen, M; van Cingel, R E H; de Visser, E

    2016-01-01

    The purpose of this retrospective cohort study was to (a) describe the clinical presentation of femoroacetabular impingement (FAI) and hip labral pathology; (b) describe the accuracy of patient history and physical tests for FAI and labral pathology as confirmed by hip arthroscopy. Patients (18-6...

  13. Hip Arthropathy in Haemophilia

    Directory of Open Access Journals (Sweden)

    Christian Carulli

    2017-04-01

    Full Text Available Hip arthropathy in haemophilic patients is disabling for hip and other common target joints. Even if bleedings in the hip are not frequent, femoroacetabular alterations may affect the functional ability of patients at a very young age. A haematologic prophylaxis combined with an adequate lifestyle and regular and low-traumatic physical activity are the keys to preventing such arthropathy. In the early stages of arthropathy, anti-inflammatory drugs and physical therapy may be sufficient to limit its progression. In cases of recurrent symptoms, viscosupplementation with hyaluronic acid, and chemical synoviorthesis are useful options. In more advanced stages, hip arthroscopy may be treated by synovectomy or loose body removal. For late stages, total hip arthroplasty (THA is mandatory. Until a few decades ago, the clinical outcomes after hip arthroplasty were variable, due to the different management of patients and the use of old generation implants and couplings. In the last decade, the introduction of the multidisciplinary management and the use of modern cementless implants with high performing materials and less invasive surgical techniques have dramatically improved the functional results. Nowadays, as is the case for other target joints, the purpose of the management in haemophilia centers is the early detection of any hip alterations—by clinical and ultrasound (US evaluations of patients in childhood—to reveal any early articular damage and to provide adequate treatment in case of symptoms. The present paper represents an updated review of the several approaches to hip arthropathy in haemophilia.

  14. TREATMENT OF HIP DYSPLASIA

    Directory of Open Access Journals (Sweden)

    Iulian ICLEANU

    2015-11-01

    Full Text Available In this thesis, our purpose is to show that using physiotherapy on patients with hip dysplasia from the very beginning, in the first months of life, helps treating them faster. Common literature proposes to use physiotherapy on patients with hip dysplasia either after their recovery or in the terminal phase of recovery, claiming that any earlier intervention will prolong the hip recovery. The effects of hip dysplasia reflect over the whole musculoskeletal system, while it hinders the knees (genu valgum, the ankles (ankle valgus, calcaneal valgus and the spine (scoliosis especially at the lumbar level. The most spectacular are at the hip level, that is why we made an analytical evaluation only for this joint. To show the importance of physiotherapy for children with hip dysplasia we started from the hypothesis: untimely treatment for children with hip dysplasia has improved results in functional recovery and in obtaining a better stability, without the necessity of orthopedics or surgical interventions. The research methods used in this study are: the observation method, the bibliographic study method, the experimental method, the graphics method and the statistical mathematical method to process the data and to represent the results graphically. In the end, the results obtained are significantly different from the initial evaluations and we came to the conclusion that starting an untimely analytical kinetic treatment and globally personalizing it to every patient improves stability and biomechanical parameters for the hip.

  15. Hip Resurfacing Implants.

    Science.gov (United States)

    Cadossi, Matteo; Tedesco, Giuseppe; Sambri, Andrea; Mazzotti, Antonio; Giannini, Sandro

    2015-08-01

    EDUCATIONAL OBJECTIVES As a result of reading this article, physicians should be able to: 1. Describe the advantages of hip resurfacing. 2. Describe the disadvantages of hip resurfacing. 3. Identify the population in which hip resurfacing is most often indicated. 4. Demonstrate how to properly postoperatively manage patients with metal-on-metal prostheses. Hip resurfacing offers a suitable solution for young patients affected by hip disease who have high function demands and good bone quality. Bone stock preservation, restoration of the normal proximal femur anatomy, the lack of stress shielding, and the possibility of resuming sporting activity are proven advantages of hip resurfacing. However, there are some disadvantages, such as fracture of the femoral neck, onset of neck narrowing, and possible complications due to the metal-on-metal bearings, including pseudotumors, peri-implant osteolysis, and chronic elevation of metal ions in serum levels. Recent data suggest that the ideal candidate for hip resurfacing is an active male, younger than 65 years, with primary or posttraumatic osteoarthritis, and with a femoral head diameter larger than 50 to 54 mm. Based on these selection criteria, the literature reports implant survival to be similar to that of total hip arthroplasty. The current authors' experience confirms a low failure rate and excellent functional outcomes, with metal ion serum levels becoming stable over time in well-functioning implants. Proper surgical technique, correct patient selection, and the right choice of a well-established prosthetic model are essential elements for the long-term success of these implants.

  16. Formed HIP Can Processing

    Energy Technology Data Exchange (ETDEWEB)

    Clarke, Kester Diederik [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2015-07-27

    The intent of this report is to document a procedure used at LANL for HIP bonding aluminum cladding to U-10Mo fuel foils using a formed HIP can for the Domestic Reactor Conversion program in the NNSA Office of Material, Management and Minimization, and provide some details that may not have been published elsewhere. The HIP process is based on the procedures that have been used to develop the formed HIP can process, including the baseline process developed at Idaho National Laboratory (INL). The HIP bonding cladding process development is summarized in the listed references. Further iterations with Babcock & Wilcox (B&W) to refine the process to meet production and facility requirements is expected.

  17. 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.

  18. The accuracy and the safety of individualized 3D printing screws insertion templates for cervical screw insertion.

    Science.gov (United States)

    Deng, Ting; Jiang, Minghui; Lei, Qing; Cai, Lihong; Chen, Li

    2016-12-01

    Clinical trial for cervical screw insertion by using individualized 3-dimensional (3D) printing screw insertion templates device. The objective of this study is to evaluate the safety and accuracy of the individualized 3D printing screw insertion template in the cervical spine. Ten patients who underwent posterior cervical fusion surgery with cervical pedicle screws, laminar screws or lateral mass screws between December 2014 and December 2015 were involved in this study. The patients were examined by CT scan before operation. The individualized 3D printing templates were made with photosensitive resin by a 3D printing system to ensure the screw shafts entered the vertebral body without breaking the pedicle or lamina cortex. The templates were sterilized by a plasma sterilizer and used during the operation. The accuracy and the safety of the templates were evaluated by CT scans at the screw insertion levels after operation. The accuracy of this patient-specific template technique was demonstrated. Only one screw axis greatly deviated from the planned track and breached the cortex of the pedicle because the template was split by rough handling and then we inserted the screws under the fluoroscopy. The remaining screws were inserted in the track as preoperative design and the screw axis deviated by less than 2 mm. Vascular or neurologic complications or injuries did not happen. And no infection, broken nails, fracture of bone structure, or screw pullout occurred. This study verified the safety and the accuracy of the individualized 3D printing screw insertion templates in the cervical spine as a kind of intraoperative screw navigation. This individualized 3D printing screw insertion template was user-friendly, moderate cost, and enabled a radiation-free cervical screw insertion.

  19. [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.

  20. 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.

  1. The other hip in unilateral hip dysplasia

    DEFF Research Database (Denmark)

    Jacobsen, Steffen; Rømer, Lone; Søballe, Kjeld

    2006-01-01

    We reviewed transverse pelvic computed tomography scans of 197 consecutively referred adult patients with hip pain thought to be secondary to developmental dysplasia. A center-edge angle of 20 degrees or less was considered the upper normal value. Four groups were identified: 69 patients with app...

  2. Total hip arthroplasty

    Directory of Open Access Journals (Sweden)

    Slavković Nemanja

    2012-01-01

    Full Text Available Total hip arthroplasty is most common reconstructive hip procedure in adults. In this surgery we replace some parts of the upper femur and acetabulum with biocompatible materials. The main goal of this surgery is to eliminate pain and regain full extent of joint motion, maintaining hip stability. Surgical technique, biomaterials, design of the prosthesis and fixation techniques have evolved with time adjusting to each other. After total hip arthroplasty patients’ quality of life should be improved. There are many various postoperative complications. Some of them are fatal, and some are minor, which may become manifested years after surgery. Each next surgical procedure following previous hip surgery is associated with considerably lower chances to be successful. Therefore, in primary total hip arthroplasty, preoperative evaluation and preparation of patients are essential. Every orthopaedic surgeon needs to improve already adopted surgical skills applying them with precision and without compromise, with the main goal to achieve long-term durability of the selected implant. The number of total hip arthroplasties will also increase in future, and newer and higher quality materials will be used.

  3. Prevention of hip fractures.

    Science.gov (United States)

    Meunier, P J

    1993-11-30

    For a 50-year old Caucasian woman today, the risk of a hip fracture over her remaining life-time is about 17%. Tomorrow the situation will clearly be worse because the continuous increase in life expectancy will cause a three-fold increase in worldwide fracture incidence over the next 60 years. Through diagnostic bone mass measurements at the hip and assessment of biochemical parameters, a great deal has been learned in recent years about reduction of hip fracture risk. Preventive strategies are based on prevention of falls, use of hip protectors, and prevention of bone fragility. The latter includes the optimization of peak bone mass during childhood, postmenopausal estrogen replacement therapy, and also late prevention consisting in reversing senile secondary hyperparathyroidism, which plays an important role in the decrease of skeletal strength. This secondary hyperparathyroidism, which results from both vitamin D insufficiency and low calcium intake, is preventable with vitamin D3 and calcium supplements. They have recently been shown capable of providing effective prevention of hip fractures in elderly women living in nursing homes, with a reduction of about 25% in the number of hip fractures noted in a 3-year controlled study in 3,270 women (intention-to-treat analysis). In conclusion, it is never too early to reduce the risk of osteoporosis and never too late to prevent hip fractures.

  4. Inverse Kinematics of a Humanoid Robot with Non-Spherical Hip: A Hybrid Algorithm Approach

    OpenAIRE

    2013-01-01

    This paper describes an approach to solve the inverse kinematics problem of humanoid robots whose construction shows a small but non negligible offset at the hip which prevents any purely analytical solution to be developed. Knowing that a purely numerical solution is not feasible due to variable efficiency problems, the proposed one first neglects the offset presence in order to obtain an approximate “solution” by means of an analytical algorithm based on screw theory, a...

  5. Periprosthetic fractures in the resurfaced hip--A case report and review of the literature.

    LENUS (Irish Health Repository)

    Brennan, Stephen A

    2013-02-01

    Traumatic periprosthetic fractures adjacent a hip resurfacing prosthesis are rare. When proximal fractures are encountered the obvious surgical solution is to revise to a large head stemmed femoral component. A previously well functioning implant may however be retained as various non-operative and operative treatment options exist. This paper reports the case history of a traumatic periprosthetic fracture successfully treated with cannulated screw fixation and reviews the current literature.

  6. 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.

  7. 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.

  8. Better Axial Stiffness of a Bicortical Screw Construct Compared to a Cable Construct for Comminuted Vancouver B1 Proximal Femoral Fractures.

    Science.gov (United States)

    Griffiths, Jamie T; Taheri, Arash; Day, Robert E; Yates, Piers J

    2015-12-01

    The aim of this study was to biomechanically evaluate the Locking attachment plate (LAP) construct in comparison to a Cable plate construct, for the fixation of periprosthetic femoral fractures after cemented total hip arthroplasty. Each construct incorporated a locking compression plate with bi-cortical locking screws for distal fixation. In the Cable construct, 2 cables and 2 uni-cortical locking screws were used for proximal fixation. In the LAP construct, the cables were replaced by a LAP with 4 bi-cortical locking screws. The LAP construct was significantly stiffer than the cable construct under axial load with a bone gap (P=0.01). The LAP construct offers better axial stiffness compared to the cable construct in the fixation of comminuted Vancouver B1 proximal femoral fractures.

  9. Guided pedicle screw insertion: techniques and training.

    Science.gov (United States)

    Manbachi, Amir; Cobbold, Richard S C; Ginsberg, Howard J

    2014-01-01

    In spinal fusion surgery, the accuracy with which screws are inserted in the pedicle has a direct effect on the surgical outcome. Accurate placement generally involves considerable judgmental skills that have been developed through a lengthy training process. Because the impact of misaligning one or more pedicle screws can directly affect patient safety, a number of navigational and trajectory verification approaches have been described and evaluated in the literature to provide some degree of guidance to the surgeon. To provide a concise review to justify the need and explore the current state of developing navigational or trajectory verification techniques for ensuring proper pedicle screw insertion along with simulation methods for better educating the surgical trainees. Recent literature review. To justify the need to develop new methods for optimizing pedicle screw paths, we first reviewed some of the recent publications relating to the statistical outcomes for different types of navigation along with the conventional freehand (unassisted) screw insertion. Second, because of the importance of providing improved training in the skill of accurate screw insertion, the training aspects of relevant techniques are considered. The third part is devoted to the description of specific navigational assist methods or trajectory verification techniques and these include computer-assisted navigation, three-dimensional simulations, and also electric impedance and optical and ultrasonic image-guided methods. This article presents an overview of the need and the current status of the guidance methods available for improving the surgical outcomes in spinal fusion procedures. It also describes educational aids that have the potential for reducing the training process. Copyright © 2014 Elsevier Inc. All rights reserved.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. 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.)

  15. 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...

  16. 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.

  17. 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.

  18. 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...

  19. 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.

  20. Hip arthroscopy in the setting of hip dysplasia

    Science.gov (United States)

    Yeung, M.; Kowalczuk, M.; Simunovic, N.

    2016-01-01

    Objective Hip arthroscopy in the setting of hip dysplasia is controversial in the orthopaedic community, as the outcome literature has been variable and inconclusive. We hypothesise that outcomes of hip arthroscopy may be diminished in the setting of hip dysplasia, but outcomes may be acceptable in milder or borderline cases of hip dysplasia. Methods A systematic search was performed in duplicate for studies investigating the outcome of hip arthroscopy in the setting of hip dysplasia up to July 2015. Study parameters including sample size, definition of dysplasia, outcomes measures, and re-operation rates were obtained. Furthermore, the levels of evidence of studies were collected and quality assessment was performed. Results The systematic review identified 18 studies investigating hip arthroscopy in the setting of hip dysplasia, with 889 included patients. Criteria used by the studies to diagnose hip dysplasia and borderline hip dysplasia included centre edge angle in 72% of studies but the range of angles were quite variable. Although 89% of studies reported improved post-operative outcome scores in the setting of hip dysplasia, revision rates were considerable (14.1%), with 9.6% requiring conversion to total hip arthroplasty. Conclusion The available orthopaedic literature suggests that although improved outcomes are seen in hip arthroscopy in the setting of hip dysplasia, there is a high rate of re-operation and conversion to total hip arthroplasty. Furthermore, the criteria used to define hip dysplasia vary considerably among published studies. Cite this article: M. Yeung, M. Kowalczuk, N. Simunovic, O. R. Ayeni. Hip arthroscopy in the setting of hip dysplasia: A systematic review. Bone Joint Res 2016;5:225–231. DOI: 10.1302/2046-3758.56.2000533. PMID:27313136

  1. Reverse LISS plating for intertrochanteric Hip Fractures in elderly patients

    Directory of Open Access Journals (Sweden)

    Chen SB

    2010-07-01

    Full Text Available Abstract Background Fractures of the intertrochanteric hip are common and the treatment of unstable fractures generally requires an operative approach. In elderly patients, osteoporosis makes internal fixation problematic and frequently contributes to failed fixation and poor clinical results. We have attempted to apply the Less Invasive Stabilization System (LISS in reverse position for the repair of intertrochanteric hip fractures in elderly patients with osteoporotic bones. A retrospective review is presented of the cases of 28 elderly patients with stable and unstable fractures of the intertrochanteric hip treated using the reverse LISS. Methods We treated 28 elderly patients with a mean age of 82.3 years. According to the Evens classification, there were 2 Type I fractures, 2 Type II fractures, 3 Type III fractures, 13 Type IV fractures, 6 Type V fractures and 2 Type R fractures. All fractures were treated using the reverse LISS. Radiographic and clinical evidence of functional outcome and complications were evaluated. Results Mean perioperative blood loss was 92.4 milliliters (range 35 to 245 milliliters, and the mean postoperative hospital stay was 8.7 days (range 3 to 14 days. Complications included one minor wound hematoma. Radiographically, no collapses, screw cutouts, or head penetrations were seen. All surviving patients (28 of 28; 100 percent had uneventful fracture healing with union achieved by six months in all patients. Conclusions Use of the Reverse LISS plating for intertrochanteric hip fractures resulted in event-free fracture healing.

  2. Hip Implant Systems

    Science.gov (United States)

    ... made of metal or ceramic, and the socket (acetabulum) is removed and replaced with a prosthetic cup. ... its socket in the hip bone (pelvis) Bone fracture Joint infection Local nerve damage with numbness/weakness ...

  3. HIP osteoarthritis and work.

    Science.gov (United States)

    Harris, E Clare; Coggon, David

    2015-06-01

    Epidemiological evidence points strongly to a hazard of hip osteoarthritis from heavy manual work. Harmful exposures may be reduced by the elimination or redesign of processes and the use of mechanical aids. Reducing obesity might help to protect workers whose need to perform heavy lifting cannot be eliminated. Particularly high relative risks have been reported in farmers, and hip osteoarthritis is a prescribed occupational disease in the UK for long-term employees in agriculture. Even where it is not attributable to employment, hip osteoarthritis impacts importantly on the capacity to work. Factors that may influence work participation include the severity of disease, the physical demands of the job, age and the size of the employer. Published research does not provide a strong guide to the timing of return to work following hip arthroplasty for osteoarthritis, and it is unclear whether patients should avoid heavy manual tasks in their future employment.

  4. 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

  5. Hip-Hop

    Institute of Scientific and Technical Information of China (English)

    张敬伟

    2008-01-01

    Hip-Hop是一种美国街头黑人文化,可分成五个要素:音乐、舞蹈、涂鸦、刺青和衣著。源自80年代美国纽约的黑人社区BRONX,他们将生活上的娱乐发展成为现今多样的HIP-HOP文化,发挥黑

  6. Posterior lumbar interbody fusion with cortical bone trajectory screw fixation versus posterior lumbar interbody fusion using traditional pedicle screw fixation for degenerative lumbar spondylolisthesis: a comparative study.

    Science.gov (United States)

    Sakaura, Hironobu; Miwa, Toshitada; Yamashita, Tomoya; Kuroda, Yusuke; Ohwada, Tetsuo

    2016-11-01

    OBJECTIVE Several biomechanical studies have demonstrated the favorable mechanical properties of the cortical bone trajectory (CBT) screw. However, no reports have examined surgical outcomes of posterior lumbar interbody fusion (PLIF) with CBT screw fixation for degenerative spondylolisthesis (DS) compared with those after PLIF using traditional pedicle screw (PS) fixation. The purposes of this study were thus to elucidate surgical outcomes after PLIF with CBT screw fixation for DS and to compare these results with those after PLIF using traditional PS fixation. METHODS Ninety-five consecutive patients underwent PLIF with CBT screw fixation for DS (CBT group; mean followup 35 months). A historical control group consisted of 82 consecutive patients who underwent PLIF with traditional PS fixation (PS group; mean follow-up 40 months). Clinical status was assessed using the Japanese Orthopaedic Association (JOA) scale score. Fusion status was assessed by dynamic plain radiographs and CT. The need for additional surgery and surgery-related complications was also evaluated. RESULTS The mean JOA score improved significantly from 13.7 points before surgery to 23.3 points at the latest follow-up in the CBT group (mean recovery rate 64.4%), compared with 14.4 points preoperatively to 22.7 points at final follow-up in the PS group (mean recovery rate 55.8%; p fusion was achieved in 84 patients from the CBT group (88.4%) and in 79 patients from the PS group (96.3%, p > 0.05). Symptomatic adjacent-segment disease developed in 3 patients from the CBT group (3.2%) compared with 9 patients from the PS group (11.0%, p fusion rate tended to be lower in the CBT group than in the PS group, although the difference was not statistically significant between the 2 groups.

  7. 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.

  8. 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.

  9. 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

  10. 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.

  11. 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.

  12. 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.

  13. Inverse Dynamics Modeling and Emulating of Flexible Multi-arthrosis Manipulator Based on Screw Theory%基于旋量理论多关节柔性机器人操作臂的逆动力学模型推导与仿真

    Institute of Scientific and Technical Information of China (English)

    王忠策; 李蕴奇

    2011-01-01

    This paper introduces the dynamics modeling and emulating of flexible multi-arthrosis manipulators on the basis of screw theory, gets a inverse dynamic equation, and analyzes the control problem that the balance is broken while the terminal performer grasps a load.Through emulating, it can be proved that this algorithm has more strong stability and reflecting velocity and simplifies the complex computing processes by Newton-Euler method and others.%基于旋量理论和方法,通过仿真给出了微型多关节整体柔性机器人操作臂的动力学模型推导及适于实现的逆动力学方程,并分析了终端执行器抓持物体平衡被破坏的控制问题.仿真结果表明,该算法稳定性强、反应速度快,简化了传统牛顿-欧拉等方法的复杂计算过程,终端执行器的位置随负载变化误差较小.

  14. 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

  15. TIP APEX DISTANCE OF INTRAMEDULLARY DEVICES AS A PREDICTOR OF CUT-OUT FAILURE IN TREATMENT OF PERITROCHANTERIC ELDERLY HIP FRACTURES

    Directory of Open Access Journals (Sweden)

    Purushotham K

    2017-02-01

    Full Text Available BACKGROUND A Tip-Apex Distance (TAD of greater than 25 mm has been shown to be an accurate predictor of lag screw cut-out when Sliding Hip Screws (SHS are used to treat Peritrochanteric (PT fractures. The purpose of this study was to determine, which factors, including TAD correlated with successful clinical outcomes of PT hip fractures surgically treated with intramedullary devices. MATERIALS AND METHODS A total of 72 patients were included in this retrospective study. TAD values were radiographically analysed at a mean follow up of 13 months. This was correlated with limited functional status and rate of revision for implant failure or inability to achieve fracture union. Only 62 patients had adequate follow up to fracture union or definitive failure. RESULTS There were 36 intertrochanteric fractures and 26 subtrochanteric fractures. Overall, 5 patients (9.8% went on to experience lag screw cut out. The average TAD of patients who did not cut-out was 18 mm compared to 38 mm for those who did (p=0.012. All patients who cut-out had IT fractures. CONCLUSION The percentage of cut-outs correlated clinically to both the severity of IT fractures and the TAD. Using a cut-off of 25 mm, there was a statistically significant difference in the incidence of lag screw cut-out (p<0.001. As in sliding hip screw, surgeons should strive for a TAD less than 25 mm when using IM devices in the treatment of PT hip fractures to help avoid lag screw cut-out.

  16. Biomechanical comparison of cervical fixation via transarticular facet screws without rods versus lateral mass screws with rods.

    Science.gov (United States)

    Yi, Seong; Rim, Dae-Cheol; Nam, Ki-Se; Keem, Sang-Hyun; Murovic, Judith A; Lim, Jesse; Park, Jon

    2015-04-01

    Transarticular facet screws restore biomechanical stability to the cervical spine when posterior cervical anatomy has been compromised. This study compares the more recent, less invasive, and briefer transarticular facet screw system without rods with the lateral mass screw system with rods. For this study, 6 human cervical spines were obtained from cadavers. Transarticular facet screws without rods were inserted bilaterally into the inferior articular facets at the C5-C6 and C5-C6-C7 levels. Lateral mass screws with rods were inserted bilaterally at the same levels using Magerl's technique. All specimens underwent range of motion (ROM) testing by a material testing machine for flexion, extension, lateral bending, and axial rotation. Both fixation methods, transarticular facet screws without rods and lateral mass screws with rods, reduced all ROM measurements and increased spinal stiffness. No statistically significant differences between the 2 stabilization methods were found in ROM measurements for 1-level insertions. However, in 2-level insertions, ROM for the nonrod transarticular facet screw group was significantly increased for flexion-extension and lateral bending. Transarticular facet screws without rods and lateral mass screws with rods had similar biomechanical stability in single-level insertions. For 2-level insertions, transarticular facet screws without rods are a valid option in cervical spine repair. Copyright © 2015 Elsevier Inc. All rights reserved.

  17. Biomechanical performance of subpectoral biceps tenodesis: a comparison of interference screw fixation, cortical button fixation, and interference screw diameter.

    Science.gov (United States)

    Sethi, Paul M; Rajaram, Arun; Beitzel, Knut; Hackett, Thomas R; Chowaniec, David M; Mazzocca, Augustus D

    2013-04-01

    Subpectoral biceps tenodesis with interference screw fixation allows reproducible positioning of the tendon to help maintain the length-tension relationship. The aim of our study was to evaluate the role of cortical button fixation in isolation or as an augment to interference screw fixation and to determine if the diameter of the interference screw affected fixation strength. Thirty-two cadaveric shoulders were dissected and randomized to 1 of 4 groups: (1) 7-mm interference screw and cortical button, (2) cortical button alone, (3) 7-mm interference screw, or (4) 8-mm interference screw. Testing was performed on a materials testing system with a 100-N load cycled at 1 Hz for 5000 cycles, followed by an axial load to failure test. Cyclic displacement, ultimate load to failure, and site of failure were recorded for each specimen. The mean ultimate failure loads were 7-mm interference screw with cortical button augmentation, 237.8 ± 120.4 N; cortical button alone, 99.4 ± 16.9 N; 7-mm interference screw, 275.5 ± 56 N; 8-mm interference screw, 277.1 ± 42.1 N. All specimens failed through tendon failure at the screw-tendon-bone interface. The biomechanical performance of subpectoral biceps tenodesis with interference screw fixation was not improved with cortical button augmentation. In addition, cortical button fixation alone yielded a significantly lower ultimate load to failure compared with interference screws. Finally, the biomechanical performance of smaller-diameter interference screws with matching bone tunnels was not affected by interference screw diameter. Copyright © 2013 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Mosby, Inc. All rights reserved.

  18. Note: High-speed Z tip scanner with screw cantilever holding mechanism for atomic-resolution atomic force microscopy in liquid

    OpenAIRE

    Mohammad Reza Akrami, Seyed; Miyata, Kazuki; Asakawa, Hitoshi; Fukuma, Takeshi

    2014-01-01

    High-speed atomic force microscopy has attracted much attention due to its unique capability of visualizing nanoscale dynamic processes at a solid/liquid interface. However, its usability and resolution have yet to be improved. As one of the solutions for this issue, here we present a design of a high-speed Z-tip scanner with screw holding mechanism. We perform detailed comparison between designs with different actuator size and screw arrangement by finite element analysis. Based on the desig...

  19. DESIGN PROPOSAL OF SCREW PUMP STRUCTURED A SWITCHED RELUCTANCE MOTOR (SP-SRM

    Directory of Open Access Journals (Sweden)

    Ahmet FENERCİOĞLU

    2008-03-01

    Full Text Available Structure of a Switched Reluctance Motor (SRM has double salient poles and does not include permanent magnet, conductor and bar. Therefore, this geometrical structure is intended to be used as an advantage for the screw pump proposal; magnetic rotor has been designed partially, inspired from the structure of radial and axial flux SRM. Proposed SRM has 6/4 poles and 3 phase configuration. Screw rotor, which is made of non-magnetic material, has been installed between magnetic rotor and the rotor structure of the screw pump has been obtained. In stator, there are 4 coils of 2000 turns installed in flux path for each phase. The screw rotor isn't included in the magnetic coupling. Here the pump rotor itself is an actuator of direct drive application. This system has been called as SP-SRM. Electrical and magnetic quantities like inductance, torque, power, magnetic flux of the SPSRM have been calculated analytically and predicted by finite elements method (Ansoft Maxwell 3D; it doesn't cover mechanics and dynamics of the proposed system. In the direct drive actuator application where the rotor itself is considered as an actuator, the SP-SRM looks like an attractive choice with its superiority of eliminating the used of a driver motor, couplings and gear boxes.

  20. 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.

  1. Sonography for hip joint effusion in adults with hip pain

    NARCIS (Netherlands)

    S.M. Bierma-Zeinstra (Sita); A.M. Bohnen (Arthur); J.A.N. Verhaar (Jan); A. Prins (Ad); J.S. Lameris; A.Z. Ginai (Abida)

    2000-01-01

    textabstractOBJECTIVE: To study the prevalence of ultrasonic hip joint effusion and its relation with clinical, radiological and laboratory (ESR) findings in adults with hip pain. METHODS: Patients (n = 224) aged 50 years or older with hip pain, referred by the general

  2. sign hip construct: achieving hip fracture fixation without using an ...

    African Journals Online (AJOL)

    Objective: The aim of this study was to assess outcomes of using the SIGN Hip Construct (SHC) to achieve ... The majority (76%) of patients were ambulatory within. 3 days after the surgery. ... Conclusion: Using the SIGN Hip Construct, hip fracture fixation can be ... elderly has made stable reduction and internal fixation.

  3. Strategy for salvage pedicle screw placement: A technical note.

    Science.gov (United States)

    Fujibayashi, Shunsuke; Takemoto, Mitsuru; Neo, Masashi; Matsuda, Shuichi

    2013-01-01

    Salvage surgery for failed lumbar spine fusion with a loosened pedicle screw is challenging. In general, the strategy includes replacement with larger and longer pedicle screws, augmentation with polymethylmethacrylate cement or hydroxyapatite granules, and extension of fused segments. The purpose of this study is to introduce a new technique for pedicle screw replacement after failed lumbar spine fusion. Five salvage operations were performed using a different trajectory (DT) pedicle screw replacement technique based on 3-dimensional radiological information. Position of the alternative pedicle screws was planned carefully on the computer screen of a computed tomography-based navigation system before the operation. To obtain sufficient initial stability, 1 of 2 techniques was chosen, depending on the patient. One technique created a completely new route, which did not interfere with the existing screw hole, and the other involved penetration of the existing screw hole. DT pedicle screws were replaced successfully according to the preoperative plan. In all patients, bony union were achieved at the final follow-up period without any instrument failure. Extension of the fused segments could be avoided by using the DT pedicle screw replacement technique combined with transforaminal lumbar interbody fusion. The DT pedicle screw replacement technique is a treatment option for salvage lumbar spine surgery. The current technique is a treatment option for salvage operations that can both avoid extension of a fused segment and achieve successful bony union.

  4. Pseudoarthrosis of the ilium after periacetabular osteotomy that was treated by cemented total hip arthroplasty: a case report.

    Science.gov (United States)

    Kanaji, Arihiko; Nishiwaki, Toru; Oya, Akihito; Maehara, Kazuyuki; Maehara, Hideki; Oishi, Teruyo; Yamada, Harumoto; Suda, Yasunori; Nakamura, Masaya; Matsumoto, Morio

    2016-05-06

    Preserving the hip joint to delay arthroplasty for patients with acetabular dysplasia-associated early-stage osteoarthritis has become more common, and several surgical procedures have demonstrated pain relief and improved hip joint function. Periacetabular osteotomy, one of the joint-preserving surgical procedures of the hip, provides favorable outcomes, although there are no reports of total hip arthroplasty being used to treat pseudoarthrosis of the periacetabular osteotomy segment. Therefore, we report a case of pseudoarthrosis in the osteotomy segment after periacetabular osteotomy. The patient was treated using modified total hip arthroplasty and achieved a favorable short-term outcome. A 62-year-old Japanese woman was diagnosed with bilateral acetabular dysplasia at the age of 50 years, and underwent right and left periacetabular osteotomy at the ages of 52 and 55 years, respectively. When she was 61-years old, she experienced repeated episodes of left coxalgia during walking, with increasing pain at rest, and subsequently visited our department. Plain radiography and computed tomography of her left hip joint confirmed pseudoarthrosis of the periacetabular osteotomy segment. In addition, narrowing of her left hip joint space was observed, which indicated advanced osteoarthritis of the hip. Therefore, she underwent left total hip arthroplasty when she was 62-years old. During the surgery, fibrous fusion of the periacetabular osteotomy segment was confirmed via fluoroscopy, although no abnormal mobility was observed. Thus, the osteotomy segment was fixed with one absorbable screw and two bone pegs (which were prepared using allogeneic bone), and the acetabular cup was fixed using cement. Her postoperative course was generally favorable and bone fusion of the periacetabular osteotomy segment was confirmed at 3 years and 6 months after surgery. Her modified Harris hip score was 43 before the surgery and had improved to 90 at the final follow-up. Modified total

  5. The applicability of PEEK-based abutment screws.

    Science.gov (United States)

    Schwitalla, Andreas Dominik; Abou-Emara, Mohamed; Zimmermann, Tycho; Spintig, Tobias; Beuer, Florian; Lackmann, Justus; Müller, Wolf-Dieter

    2016-10-01

    The high-performance polymer PEEK (poly-ether-ether-ketone) is more and more being used in the field of dentistry, mainly for removable and fixed prostheses. In cases of screw-retained implant-supported reconstructions of PEEK, an abutment screw made of PEEK might be advantageous over a conventional metal screw due to its similar elasticity. Also in case of abutment screw fracture, a screw of PEEK could be removed more easily. M1.6-abutment screws of four different PEEK compounds were subjected to tensile tests to set their maximum tensile strengths in relation to an equivalent stress of 186MPa, which is aused by a tightening torque of 15Ncm. Two screw types were manufactured via injection molding and contained 15% short carbon fibers (sCF-15) and 40% (sCF-40), respectively. Two screw types were manufactured via milling and contained 20% TiO2 powder (TiO2-20) and >50% parallel orientated, continuous carbon fibers (cCF-50). A conventional abutments screw of Ti6Al4V (Ti; CAMLOG(®) abutment screw, CAMLOG, Wimsheim, Germany) served as control. The maximum tensile strength was 76.08±5.50MPa for TiO2-20, 152.67±15.83MPa for sCF-15, 157.29±20.11MPa for sCF-40 and 191.69±36.33MPa for cCF-50. The maximum tensile strength of the Ti-screws amounted 1196.29±21.4MPa. The results of the TiO2-20 and the Ti screws were significantly different from the results of the other samples, respectively. For the manufacturing of PEEK abutment screws, PEEK reinforced by >50% continuous carbon fibers would be the material of choice. Copyright © 2016 Elsevier Ltd. All rights reserved.

  6. HIP-HOP

    Institute of Scientific and Technical Information of China (English)

    QunyKing; 人在羽中; 钱李明

    2005-01-01

    自从一群摇滚青年开始跟风 Elvis 的《Blue SuedeShoes》风格,hip-hop 似乎就成为了全球最具影响力的音乐风格。它最初起源于美国的黑人和拉丁美洲人,之后迅速在全世界流行,成为80年代、90年代和新千年的主流音乐。无论是在广告界还是在电影业,从各类排行榜到各种酒吧,hip-hop 的影响逐年增加。在1997年,英国的 hip-hop 还只是一种地下音

  7. Developmental Dysplasia of the Hip

    Science.gov (United States)

    ... in the motion of the hip and obvious shortening of the affected leg in older kids, an ... socket. During the procedure, doctors loosen the tight muscles and tissues around the hip joint and then ...

  8. 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.

  9. 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.

  10. 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.

  11. Hip resurfacing: a technology reborn

    OpenAIRE

    2006-01-01

    In recent years there has been a resurgence of interest in the concept of hip resurfacing. Much of this interest has stemmed from the work of McMinn in the West Midlands. Hip resurfacing is now emerging as a viable alternative to conventional hip replacement. In this article, we discuss the conceptual advantages offered by hip resurfacing and review the early clinical results and the ongoing clinical concerns regarding this technology.

  12. 经皮加压钢板与动力髋螺钉治疗股骨转子间骨折的Meta分析%A meta-analysis of percutaneous compression plate versus dynamic hip screw for treatment of intertrochanteric hip fractures

    Institute of Scientific and Technical Information of China (English)

    唐天华; 谭文成; 唐三元; 杨辉; 朱亚平; 黄馨霈

    2015-01-01

    [目的]对经皮加压钢板(PCCP)与动力髋螺钉(DHS)内固定治疗股骨转子间骨折疗效与并发症进行评价.[方法]按照Cochrane系统评价的方法,计算机检索下列数据库:Medline、Pubmed、SPINGER、John Wi-ley、Science Direct、EBSCO、CNKI、万方数数据库,并采用手工检索等方法收集文献.检索时间为1998年1月~2013年8月.收集所有相关随机对照试验,采用Cochrane协作网提供的软件Revman5.1进行Meta分析.[结果]经过筛选,共纳入5个临床随机对照试验463例患者.Meta分析显示PCCP组与DHS组在手术时间(95% CI:-26.01~4.05,P=0.15)、住院时间(95% CI:-1.79 ~ 1.25,P=0.73)、死亡率(95%CI:0.37~1.02,P=0.06)、置入物相关并发症(95% CI:0.29~1.82,P=0.49)和再手术率(95%CI:0.41 ~3.05,P=0.83)上无明显统计学差异.但两组患者出血量(95%CI:-173.84~-4.81,P=0.04)和输血量(95%CI:-0.53~-0.07,P=0.01)有明显差异,PCCP组较DHS组明显减少.[结论]PCCP与DHS相比能减少出血和输血量,但在其他方面基本相同.由于病例数的限制,尚需要更多更高质量的临床随机对照试验来评价PCCP的效果.

  13. 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.

  14. Biomechanical comparison of interference screw and cortical button with screw hybrid technique for distal biceps brachii tendon repair.

    Science.gov (United States)

    Arianjam, Afshin; Camisa, William; Leasure, Jeremi M; Montgomery, William H

    2013-11-01

    Various fixation techniques have been described for ruptured distal biceps tendons. The authors hypothesized that no significant differences would be found between the mean failure strength, maximum strength, and stiffness of the interference screw and hybrid technique. Fourteen fresh-frozen human cadaveric elbows were prepared. Specimens were randomized to either interference screw or hybrid cortical button with screw fixation. The tendon was pulled at a rate of 4 mm/s until failure. Failure strength, maximum strength, and stiffness were measured and compared. Failure strength, maximum strength, and stiffness were 294±81.9 N, 294±82.1 N, and 64.4±40.5 N/mm, respectively, for the interference screw technique and 333±129 N, 383±121 N, and 56.2±40.5 N/mm, respectively, for the hybrid technique. No statistically significant difference existed between the screw and hybrid technique in failure strength, maximum strength, or stiffness (P>.05). The interference screws primarily failed by pullout of the screw and tendon, whereas in the hybrid technique, failure occurred with screw pullout followed by tearing of the biceps tendon. The results suggest that this hybrid technique is nearly as strong and stiff as the interference screw alone. Although the hybrid technique facilitates tensioning of the reconstructed tendon, the addition of the cortical button did not significantly improve the failure strength of the interference screw alone. Copyright 2013, SLACK Incorporated.

  15. 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.

  16. X-Ray Exam: Hip

    Science.gov (United States)

    ... Old Feeding Your 1- to 2-Year-Old X-Ray Exam: Hip KidsHealth > For Parents > X-Ray Exam: Hip A A A What's in ... español Radiografía: cadera What It Is A hip X-ray is a safe and painless test that ...

  17. 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

  18. 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...

  19. 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.

  20. 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

  1. Treatment of hip instability.

    Science.gov (United States)

    Robbins, G M; Masri, B A; Garbuz, D S; Greidanus, N; Duncan, C P

    2001-10-01

    Instability after total hip arthroplasty is a major source of patient morbidity, second only to aseptic loosening. Certain patient groups have been identified as having a greater risk of instability, including patients undergoing revision arthroplasty as early or late treatment for proximal femoral fractures.

  2. INL HIP Plate Fabrication

    Energy Technology Data Exchange (ETDEWEB)

    B. H. Park; C. R. Clark; J. F. Jue

    2010-02-01

    This document outlines the process used to bond monolithic fuel plates by Hot Isostatic Pressing (HIP). This method was developed at Idaho National Laboratory (INL) for the Reduced Enrichment for Research and Test Reactors (RERTR) program. These foils have been used in a number of irradiation experiments in support of the United States Global Threat Reduction Initiative (GTRI) program.

  3. Pain management after surgery in hip fracture patients: A randomized placebo controlled trial%髋部骨折术后疼痛管理的随机对照研究

    Institute of Scientific and Technical Information of China (English)

    胡承方; 罗从风; 陈云苏; 张巍; 杨光; 朱奕

    2012-01-01

    目的 通过对髋部骨折术后患者进行疼痛评价,分析术后疼痛与骨折类型、手术方式、镇痛方法之间的关系,为进一步完善髋部骨折术后疼痛管理提供依据.方法 采用前瞻性、随机对照研究,83例髋部骨折根据镇痛方法分成3组:①帕瑞昔布组;②塞来昔布组;③安慰剂组.根据手术方式不同分成4组:①空心钉内固定组;②DHS内固定组;③髓内钉内固定组;④髋关节置换组.比较术前、术后的疼痛视觉模拟评分(VAS),术后3d的疼痛缓解程度,并发症率以及患者满意度.结果 患者的年龄及骨折类型对髋部骨折术后疼痛的影响有限,DHS和髓内钉内固定组患者的疼痛程度比空心钉内固定和关节置换组要高;帕瑞昔布组在术后疼痛强度、疼痛缓解程度以及满意度方面与塞来昔布组和安慰剂组比较差异有统计学意义(P<0.05),但在并发症的发生率上差异无统计学意义(P>0.05).结论 要重视使用DHS和髓内钉内固定髋部骨折术后的疼痛管理,且帕瑞昔布对髋部手术术后镇痛的效果确切,具有安全、可靠、起效快的优点.%Objective To analyze the relationship between postoperative pain and a variety of factors, including fracture type, type of surgery, and pain management protocol by performing pain assessment in hip fracture patients after surgery for the optimum protocol for postoperative pain management. Methods This was a prospective, randomized, placebo-controlled study. A total of 83 hip fracture patients randomly received one of the three analgesics for pain control; i.e., parecoxib, celecoxib, and placebo. The surgical procedures that were used included cannulated screw internal fixation, dynamic hip screw (DHS) internal fixation, intramedullary nail internal fixation, and hip arthroplasty. Comparisons were made in visual analogue scale scores, pain relief of the first three postoperative days, incidence of complications, and patient

  4. Hip Arthroscopy: A Brief History.

    Science.gov (United States)

    Kandil, Abdurrahman; Safran, Marc R

    2016-07-01

    Hip arthroscopy is a fast-growing and evolving field. Like knee and shoulder arthroscopy, hip arthroscopy began as a diagnostic procedure and then progressed to biopsy and resection of abnormalities. Subsequently, it has evolved to repair of various tissues and treatment of underlying causes. As the understanding of the hip joint and its associated pathophysiology grows, indications will continue to expand for this diagnostic and therapeutic modality. This article outlines the historic developments of hip arthroscopy, including advancements in instrumentation and techniques from the days of the first hip arthroscopies to the present day.

  5. Unified Singularity Modeling and Reconfiguration of 3rTPS Metamorphic Parallel Mechanisms with Parallel Constraint Screws

    Directory of Open Access Journals (Sweden)

    Yufeng Zhuang

    2015-01-01

    Full Text Available This paper presents a unified singularity modeling and reconfiguration analysis of variable topologies of a class of metamorphic parallel mechanisms with parallel constraint screws. The new parallel mechanisms consist of three reconfigurable rTPS limbs that have two working phases stemming from the reconfigurable Hooke (rT joint. While one phase has full mobility, the other supplies a constraint force to the platform. Based on these, the platform constraint screw systems show that the new metamorphic parallel mechanisms have four topologies by altering the limb phases with mobility change among 1R2T (one rotation with two translations, 2R2T, and 3R2T and mobility 6. Geometric conditions of the mechanism design are investigated with some special topologies illustrated considering the limb arrangement. Following this and the actuation scheme analysis, a unified Jacobian matrix is formed using screw theory to include the change between geometric constraints and actuation constraints in the topology reconfiguration. Various singular configurations are identified by analyzing screw dependency in the Jacobian matrix. The work in this paper provides basis for singularity-free workspace analysis and optimal design of the class of metamorphic parallel mechanisms with parallel constraint screws which shows simple geometric constraints with potential simple kinematics and dynamics properties.

  6. Acetabular anatomy and the relationship with pelvic vascular structures. Implications in hip surgery.

    Science.gov (United States)

    Feugier, P; Fessy, M H; Béjui, J; Bouchet, A

    1997-01-01

    Most direct vascular trauma occurring during hip surgery results from injury to pelvic vascular structures which are not visible during the procedures of reaming, drilling holes or the fixation of screws. In this study, 5 pelves of fresh cadavers were injected with a radiopaque mixture and were visualised with a scanner according to 5 predetermined sections. Bone depth of the acetabulum was measured in each section. A calculation was made describing the minimal distance separating the inner cortex from the principal pelvic vessels. After an anatomic dissection of each pelvis, the relationship between the vessels and screws of the fixation cup, implanted identically on the quadranted acetabulum, was observed. The screws placed in the anterior and inferior quadrants and the center of the acetabulum endangered the external iliac v. and a. and the obturator pedicle. The depth of the periacetabular bone was greater in the superior and posterior quadrants. The inferior gluteal, pudendal and superior gluteal aa. were more than ten mm from the posterior wall. Conversely, the external iliac and obturator pedicles came in contact with the osseous surface on which they lay. A projection of the vessels on the acetabulum was made, and the reproducible character of the acetabular-quadrant system was verified. The superior quadrant offers all the characteristics of a vascular safe zone. A knowledge of these anatomic relationships explain vascular trauma in pelvic fractures and helps to prevent vascular injury in hip surgery.

  7. Conus hip prosthesis.

    Science.gov (United States)

    Wagner, H; Wagner, M

    2001-01-01

    50 years ago, prosthetic replacement of the hip joint ushered in a new epoch in orthopaedics. Total hip replacement made it possible to remove a severely diseased, painful hip and restore normal function and a normal quality of life to the afflicted patient. The early results of total hip replacement are almost all spectacular and hip replacement has become the most successful type of orthopaedic surgery. These good results using an approach that was technically relatively simple resulted in a temptation to implant prosthetic hip joints with ever increasing frequency in ever younger patients. This led to the emergence of new problems, which were not so clearly recognised at the outset: it emerged that the stability of prosthetic hip joints was of limited duration. This had the following consequence: If a total hip prosthesis is implanted in an elderly person whose remaining life-expectancy is shorter than the longevity of the prosthesis, hip replacement is a life-long solution. We can therefore say that, for a patient who has only 10 to 15 years left to live, their hip problem is solved by total hip replacement. For young people, who still have a long life expectancy in front of them, it is different. They will experience failure of the artificial joint and require further surgery. The commonest and most important type of failure in total hip prostheses is aseptic loosening, which is associated with resorption of bone at the site of the prosthesis. The cause of this phenomenon has only gradually been recognised in the course of the years. Initially, the unanimous opinion was that the methacrylate cement, used to fix the components of the prosthesis in the bone, was the definitive cause of aseptic loosening because fissures and fractures of the cement were almost always found during surgical revision of loosened joints. There was talk of "cement disease" and great efforts were made to improve the quality of the cement and the cementing technique. Moreover, even

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

    OpenAIRE

    Tineke Saroinsong; Rudy Soenoko; Slamet Wahyudi; Mega N Sasongko

    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...

  9. 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...

  10. 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.

  11. Analysis on Energy Conversion of Screw Centrifugal Pump in Impeller Domain Based on Profile Lines

    Directory of Open Access Journals (Sweden)

    Hui Quan

    2013-01-01

    Full Text Available In order to study the power capability of impeller and energy conversion mechanism of screw centrifugal pump, the methods of theoretical analysis and numerical simulation by computational fluid dynamics theory (CFD were adopted, specifically discussing the conditions of internal flow such as velocity, pressure, and concentration. When the medium is sand-water two-phase flow and dividing the rim of the lines and wheel lines of screw centrifugal pump to segments to analyze energy conversion capabilities which along the impeller profile lines with the dynamic head and hydrostatic head changer, the results show that the energy of fluid of the screw centrifugal pump is provided by helical segment, and the helical segment of the front of the impeller has played the role of multilevel increasing energy; the sand-water two phases move at different speeds because the different force field and the impeller propeller and centrifugal effect. As liquid phase is the primary phase, the energy conversion is mainly up to the change of liquid energy, the solid phase flows under the wrapped action of liquid, and solid energy is carried out through liquid indirectly.

  12. CFD simulation of a screw compressor including leakage flows and rotor heating

    Science.gov (United States)

    Spille-Kohoff, Andreas, Dr.; Hesse, Jan; El Shorbagy, Ahmed

    2015-08-01

    Computational Fluid Dynamics (CFD) simulations have promising potential to become an important part in the development process of positive displacement (PD) machines. CFD delivers deep insights into the flow and thermodynamic behaviour of PD machines. However, the numerical simulation of such machines is more complex compared to dynamic pumps like turbines or fans. The fluid transport in size-changing chambers with very small clearances between the rotors, and between rotors and casing, demands complex meshes that change with each time step. Additionally, the losses due to leakage flows and the heat transfer to the rotors need high-quality meshes so that automatic remeshing is almost impossible. In this paper, setup steps and results for the simulation of a dry screw compressor are shown. The rotating parts are meshed with TwinMesh, a special hexahedral meshing program for gear pumps, gerotors, lobe pumps and screw compressors. In particular, these meshes include axial and radial clearances between housing and rotors, and beside the fluid volume the rotor solids are also meshed. The CFD simulation accounts for gas flow with compressibility and turbulence effects, heat transfer between gas and rotors, and leakage flows through the clearances. We show time- resolved results for torques, forces, interlobe pressure, mass flow, and heat flow between gas and rotors, as well as time- and space-resolved results for pressure, velocity, temperature etc. for different discharge ports and working points of the screw compressor. These results are also used as thermal loads for deformation simulations of the rotors.

  13. Revision of hip resurfacing arthroplasty.

    Science.gov (United States)

    Wera, Glenn D; Gillespie, Robert J; Petty, Carter; Petersilge, William J; Kraay, Matthew J; Goldberg, Victor M

    2010-08-01

    Metal-on-metal (MOM) hip resurfacing has become an increasingly popular treatment for young, active patients with degenerative disease of the hip, as bearing surfaces with better wear properties are now available. One proposed advantage of resurfacing is its ability to be successfully revised to total hip arthroplasty (THA). In addition, radiographic parameters that may predict failure in hip resurfacing have yet to be clearly defined. Seven MOM resurfacing arthroplasties were converted to conventional THAs because of aseptic failure. Using Harris Hip Scores (HHS) and Short Form 12 (SF-12) questionnaire scores, we compared the clinical outcomes of these patients with those of patients who underwent uncomplicated MOM hip resurfacing. In addition, all revisions were radiographically evaluated. Mean follow-up periods were 51 months (revision group) and 43 months (control group). There was no significant difference between the 2 groups' HHS or SF-12 scores. There was no dislocation or aseptic loosening after conversion of any resurfacing arthroplasty. Valgus neck-shaft angle (P hip resurfacing. Conversion of aseptic failure of hip resurfacing to conventional THA leads to clinical outcomes similar to those of patients who undergo uncomplicated hip resurfacing. The orientation of the femur and the components placed play a large role in implant survival in hip resurfacing. More work needs to be done to further elucidate these radiographic parameters.

  14. 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 ...

  15. [Juvenile hip pain. 2. Femur head epiphysiolysis, hip dysplasia, tumors].

    Science.gov (United States)

    Hackenbruch, W; von Gumppenberg, S; Karpf, P M

    1978-11-09

    The early symptom in hip joint diseases in children is pain. Pain is localized in the groin and thight, but mostly in the knee. Other important signs are limping and reduced internal rotation. If a hip disease is suspected it is necessary to take X-rays in two planes. If diagnosis is early and special therapy started immediately, the results are usually excellent without deformation of the hip. Otherwise early osteoarthritis can develop. This is important because osteoarthritis in the hip joint is in 75% of the cases due to hip joint diseases in childhood. The problems of diagnosis and treatment of the most common hip joint diseases in children (transient synovitis, rheumatoid arthritis, osteomyelitis, Legg-Perthes disease, slipped capital femoral epiphysis, dysplasia, tumors) are discussed.

  16. [Intraosseous screw splinting of mandibular fragments].

    Science.gov (United States)

    Erle, A

    1978-12-01

    Fractures in the frontal region of the mandible may be treated by intra-ossal splinting without the risk of injuring nerves or vessels. Function-stable fixation of the reposited fragments was achieved in 15 patients by means of a transfragmental screw with metric thread. The advantages of this procedure consist in the easy removability of the material and the superfluidity of new developments of material or instruments. As the possibility of early functional treatment prevents the late impairment of the articular function, this procedure is particularly indicated in case of concurrent paramedian and articular fractures.

  17. The rehabilitation management after hip arthroplasty: a case report

    Directory of Open Access Journals (Sweden)

    Adina BURCHICI

    2017-03-01

    Full Text Available Aim: In this paper we describe the physical therapy management of a 64-year-old female following a bilateral hip arthroplasty. Method: The patient featured in this study, after the surgical intervention had undergone specific recovery treatment consisting of: posture techniques, static (isometric contractions and dynamic kinetic techniques (passive motion, passive-actives, actives, actives with resistance, massage, respiratory gymnastics and reeducation of walking. Results: At the end of the rehabilitation program, hip muscular strength and joint range of motion were improved significantly. The Harris hip score was significantly improved, in comparison to the preoperative one. Conclusion: This case illustrates the importance of the rehabilitation management after bilateral hip replacement.

  18. Nonarthritic hip joint pain.

    Science.gov (United States)

    Enseki, Keelan; Harris-Hayes, Marcie; White, Douglas M; Cibulka, Michael T; Woehrle, Judith; Fagerson, Timothy L; Clohisy, John C

    2014-06-01

    The Orthopaedic Section of the American Physical Therapy Association (APTA) has an ongoing effort to create evidence-based practice guidelines for orthopaedic physical therapy management of patients with musculoskeletal impairments described in the World Health Organization's International Classification of Functioning, Disability, and Health (ICF). The purpose of these clinical practice guidelines is to describe the peer-reviewed literature and make recommendations related to nonarthritic hip joint pain.

  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. 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.

  2. 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.

  3. 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.

  4. 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.

  5. Ball Screw Actuator Including an Axial Soft Stop

    Science.gov (United States)

    Wingett, Paul T. (Inventor); Forrest, Steven Talbert (Inventor); Abel, Steve (Inventor); Woessner, George (Inventor); Hanlon, Casey (Inventor)

    2016-01-01

    An actuator includes an actuator housing, a ball screw, and an axial soft stop assembly. The ball screw extends through the actuator housing and has a first end and a second end. The ball screw is coupled to receive a drive force and is configured, upon receipt of the drive force, to selectively move in a retract direction and an extend direction. The axial soft stop assembly is disposed within the actuator housing. The axial soft stop assembly is configured to be selectively engaged by the ball screw and, upon being engaged thereby, to translate, with compliance, a predetermined distance in the extend direction, and to prevent further movement of the ball screw upon translating the predetermined distance.

  6. 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.

  7. A new compression design that increases proximal locking screw bending resistance in femur compression nails.

    Science.gov (United States)

    Karaarslan, Ahmet Adnan; Karakaşli, Ahmet; Karci, Tolga; Aycan, Hakan; Yildirim, Serhat; Sesli, Erhan

    2015-06-01

    The aim is to present our new method of compression, a compression tube instead of conventional compression screw and to investigate the difference of proximal locking screw bending resistance between compression screw application (6 mm wide contact) and compression tube (two contact points with 13 mm gap) application. We formed six groups each consisting of 10 proximal locking screws. On metal cylinder representing lesser trochanter level, we performed 3-point bending tests with compression screw and with compression tube. We determined the yield points of the screws in 3-point bending tests using an axial compression testing machine. We determined the yield point of 5 mm screws as 1963±53 N (mean±SD) with compression screw, and as 2929±140 N with compression tubes. We found 51% more locking screw bending resistance with compression tube than with compression screw (p=0,000). Therefore compression tubes instead of compression screw must be preferred at femur compression nails.

  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. CURBSIDE CONSULTATION IN HIP ARTHROPLASTY

    OpenAIRE

    Sporer, Scott M.; Bernard R. Bach, Jr

    2009-01-01

    DESCRIPTION A user friendly reference for decision making in hip arthroplasty designed in a question formed clinical problem scenarios and answers format .The articles composed of the answers, containing current concepts and preferences of experts in primary and revision hip surgery are enhanced by several images, diagrams and references and written in the form of a curbside consultation by Scott M. Sporer, MD. and his collaborators. PURPOSE By this practical reference of hip arthroplasty, Sc...

  11. Avaliação biomecânica da fixação da fratura supracondiliana do fêmur comparando placa-lâmina 95º com DCS Fixation of supracondylar femoral fractures: a biomechanical analysis comparingthe 95º blade plate and the dynamic condylar screw (DCS

    Directory of Open Access Journals (Sweden)

    Marco Antônio Percope Andrade

    2010-01-01

    Full Text Available OBJETIVO: Demonstrar por meio de ensaios biomecânicos comparativos entre a placa-lâmina de 95º e o parafuso condilar dinâmico (Dynamic Condylar Screw - DCS, qual apresenta maior resistência às cargas compressivas e de flexão, bem como tentar correlacionar o tipo de falha apresentada durante os testes com cada um dos tipos de placa. MÉTODOS: Sessenta e cinco fêmures suínos foram submetidos a osteotomia em cunha de subtração medial de um centímetro (cm, na região metafisária distal do fêmur, com o objetivo de simular fratura supracondiliana instável. Foi realizada osteossíntese dessas peças, sendo 35 fixadas com placa-lâmina 95º e 30 com placas com DCS, submetendo-as a cargas em compressão axial e flexão. Outra variável estudada foi o tipo de falha apresentada em cada grupo com a tentativa de correlacioná-la com o tipo de placa. RESULTADOS: Os resultados não mostraram diferença estatisticamente significante na resistência biomecânica entre os dois tipos de placas ou entre o tipo de falha e a placa utilizada na osteossíntese. CONCLUSÃO: Os dois tipos de placas se comportam de maneira semelhante, embora haja um indicativo de que a placa-lâmina seja, no ensaio de flexão, superior à placa DCS. Não foi observada diferença entre o tipo de falha e o tipo de placa utilizada.OBJECTIVE: to determine, by means of comparative biomechanical tests between the 95o angled blade plate and the dynamic condylar screw (DCS, the one that presents greater compressive load resistance and flexion, and to correlate the failure type presented during the tests with each type of plate. METHODS: Sixty-five porcine femurs were submitted to a 1 cm medial wedge osteotomy, in the metaphysic, to simulate an unstable supracondylar femoral fracture. Osteosynthesis of these pieces was performed: 35 were fixated with a 90o lateral blade plate, and 30 with DCS plates. Another variable studied was the failure type presented in each group, attempting

  12. Radiographic Classification of Developmental Dysplasia of the Hip

    Directory of Open Access Journals (Sweden)

    José Julio Requeiro Molina

    2013-08-01

    Full Text Available For over a decade, abduction splinting has been the method of treatment for developmental dysplasia of the hip in the Paquito González Cueto University Pediatric Hospital. This paper is aimed at presenting the dynamic classification for this condition from a radiographic point of view. Representative schemes and radiographies of patients with various stages of developmental hip dysplasia were used for illustrating this classification. The dynamic behavior of the radiographic parameters used in the classification allows gathering diagnostic groups before, during and after treatment in order to assess its final results.

  13. Hip Resurfacing. Case presentation. Resuperficialización de Cadera. Presentación de caso.

    Directory of Open Access Journals (Sweden)

    Tamara Elizabeth Morales Perez

    Full Text Available Hip resurfacing in youngest patients is an excellent surgical technique for Avascular Necrosis compare with a traditional Total Hip Replacement. Report about a 21 years old female patient involved in a car accident in February 2004 with Fracture of the neck of femur treated with compression hip screw Richard’s type. Two years later the patient was diagnose with avascular necrosis of the contra lateral hip. Hip resurfacing Metal-Metal was carry out in the above mentioned patient.
    La resuperficialización de la cadera en pacientes jóvenes con necrosis avascular es una novedosa técnica quirúrgica que ofrece marcadas ventajas comparadas con las técnicas convencionales de Reemplazo Total de Cadera. Se trata una paciente del sexo femenino de 21 años de edad que sufrió en un accidente de transito en febrero de 2004 con una fractura del cuello femoral por lo que se intervino quirúrgicamente con el sistema intercompresivo de Richard’s. Dos años más tarde se le diagnosticó una necrosis avascular de la cadera contra lateral por lo que se le realizó una resuperficialización de cadera metal-metal.

  14. Hip Hip Hurrah! Hip size inversely related to heart disease and total mortality

    DEFF Research Database (Denmark)

    Heitmann, B L; Lissner, L

    2011-01-01

    obesity and/or waist circumference. These studies have been remarkable in terms of their consistency, and in the unexpected finding of an adverse effect of small hip size, after statistically correcting for differences in general and abdominal size. The hazard related to a small hip size may be stronger......During the past decade a series of published reports have examined the value of studying the relation between hip circumferences and cardiovascular end points. Specifically, in a series of recent studies the independent effects of hip circumference have been studied after adjustment for general...

  15. Hip abductor weakness is not the cause for iliotibial band syndrome.

    Science.gov (United States)

    Grau, S; Krauss, I; Maiwald, C; Best, R; Horstmann, T

    2008-07-01

    Muscular deficits in the hip abductors are presumed to be a major factor in the development of Iliotibial Band Syndrome in runners. No definite relationship between muscular weakness of the hip abductors and the development of Iliotibial Band Syndrome or different ratios between hip adduction to abduction have been reported so far. Isokinetic measurements were taken from 10 healthy runners and 10 runners with Iliotibial Band Syndrome. Primary outcome variables were concentric, eccentric, and isometric peak torque of the hip abductors and adductors at 30 degrees/s, and a concentric endurance quotient at the same angle velocity. Differences in muscle strength of the hip abductors between healthy (CO) and injured runners (ITBS) were not statistically significant in any of the muscle functions tested. Both groups showed the same strength differences between hip adduction and abduction, and increased strength in hip adduction. Weakness of hip abductors does not seem to play a role in the etiology of Iliotibial Band Syndrome in runners, since dynamic and static strength measurements did not differ between groups, and differences between hip abduction and adduction were the same. Strengthening of hip abductors seems to have little effect on the prevention of Iliotibial Band Syndrome in runners.

  16. Trochanteric osteotomy in total hip replacement for congenital hip disease.

    Science.gov (United States)

    Hartofilakidis, G; Babis, G C; Georgiades, G; Kourlaba, G

    2011-05-01

    We studied the effect of trochanteric osteotomy in 192 total hip replacements in 140 patients with congenital hip disease. There was bony union in 158 hips (82%), fibrous union in 29 (15%) and nonunion in five (3%). The rate of union had a statistically significant relationship with the position of reattachment of the trochanter, which depended greatly on the pre-operative diagnosis. The pre-operative Trendelenburg gait substantially improved in all three disease types (dysplasia, low and high dislocation) and all four categories of reattachment position. A persistent Trendelenburg gait post-operatively was noticed mostly in patients with defective union (fibrous or nonunion). Acetabular and femoral loosening had a statistically significant relationship with defective union and the position of reattachment of the trochanter. These results suggest that the complications of trochanteric osteotomy in total hip replacement for patients with congenital hip disease are less important than the benefits of this surgical approach.

  17. Danish Hip Arthroscopy Registry

    DEFF Research Database (Denmark)

    Mygind-Klavsen, Bjarne; Grønbech Nielsen, Torsten; Maagaard, Niels

    2016-01-01

    and Pincer resection in 93.5% of the cases. Labral refixation or repair was done in 70.3% of the cases. The most common type of acetabular chondral damage was grade II lesions (36.6%). Grade III and IV changes were seen in 36.1% of the cases. The preoperative iHOT12 was 45 (mean) based on all 12 items. EQ-5D....... The problems with development and maintaining a large clinical registry are described and further studies are needed to validate data completeness. We consider the development of a national clinical registry for hip arthroscopy as a successful way of developing and maintaining a valuable clinical...

  18. Mechanistic modeling of modular co-rotating twin-screw extruders.

    Science.gov (United States)

    Eitzlmayr, Andreas; Koscher, Gerold; Reynolds, Gavin; Huang, Zhenyu; Booth, Jonathan; Shering, Philip; Khinast, Johannes

    2014-10-20

    In this study, we present a one-dimensional (1D) model of the metering zone of a modular, co-rotating twin-screw extruder for pharmaceutical hot melt extrusion (HME). The model accounts for filling ratio, pressure, melt temperature in screw channels and gaps, driving power, torque and the residence time distribution (RTD). It requires two empirical parameters for each screw element to be determined experimentally or numerically using computational fluid dynamics (CFD). The required Nusselt correlation for the heat transfer to the barrel was determined from experimental data. We present results for a fluid with a constant viscosity in comparison to literature data obtained from CFD simulations. Moreover, we show how to incorporate the rheology of a typical, non-Newtonian polymer melt, and present results in comparison to measurements. For both cases, we achieved excellent agreement. Furthermore, we present results for the RTD, based on experimental data from the literature, and found good agreement with simulations, in which the entire HME process was approximated with the metering model, assuming a constant viscosity for the polymer melt.

  19. Flow Field Simulation and Noise Control of a Twin-Screw Engine-Driven Supercharger

    Directory of Open Access Journals (Sweden)

    Tao Wang

    2016-01-01

    Full Text Available With the advantages of good low-speed torque capability and excellent instant response performance, twin-screw superchargers have great potential in the automobile market, but the noise of these superchargers is the main factor that discourages their use. Therefore, it is important to study their noise mechanism and methods of reducing it. This study included a transient numerical simulation of a twin-screw supercharger flow field with computational fluid dynamics software and an analysis of the pressure field of the running rotor. The results showed that overcompression was significant in the compression end stage of the supercharger, resulting in a surge in airflow to a supersonic speed and the production of shock waves that resulted in loud noise. On the basis of these findings, optimization of the supercharger is proposed, including expansion of the supercharger exhaust orifice and creation of a slot along the direction of the rotor spiral normal line at the exhaust port, so as to reduce the compression end pressure, improve the exhaust flow channel, and weaken the source of the noise. Experimental results showed that the noise level value of the improved twin-screw supercharger was significantly lower at the same speed than the original model, with an average decrease of about 5 dB (A.

  20. The injection of a screw dislocation into a crystal: Atomistics vs. continuum elastodynamics

    Science.gov (United States)

    Verschueren, J.; Gurrutxaga-Lerma, B.; Balint, D. S.; Dini, D.; Sutton, A. P.

    2017-01-01

    The injection (creation) process of a straight screw dislocation is compared atomistically with elastodynamic continuum theory. A method for injecting quiescent screw dislocations into a crystal of tungsten is simulated using non-equilibrium molecular dynamics. The resulting stress fields are compared to the those of elastodynamic solutions for the injection of a quiescent screw dislocation. A number of differences are found: a plane wave emission is observed to emanate from the whole surface of the cut used to create the dislocation, affecting the displacement field along the dislocation line (z), and introducing displacement field components perpendicular to the line (along x and y). It is argued that, in part, this emission is the result of the finite time required to inject the dislocation, whereby the atoms in the cut surface must temporarily be displaced to unstable positions in order to produce the required slip. By modelling this process in the continuum it is shown that the displacements components normal to the dislocation line arise from transient displacements of atoms in the cut surface parallel to x and y. It is shown that once these displacements are included in the elastodynamic continuum formulation the plane wave emission in uz is correctly captured. A detailed comparison between the atomistic and continuum models is then offered, showing that the main atomistic features can also be captured in the continuum.

  1. 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.

  2. 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.

  3. 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

  4. 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

  5. 动态套筒式三翼钉固定不同角度PMMA股骨颈骨折的生物力学研究%Biomechanical research of dynamic sleeve three-wing screw in fixing femoral neck fracture of different angles

    Institute of Scientific and Technical Information of China (English)

    杨阳; 马信龙; 马剑雄; 王志彬; 马宝意; 王沛

    2010-01-01

    Objective To explore the biomechanical stability of dynamic sleeve three-wing screw for treatment of femoral neck fracture and to provide theoretical basis for choosing the screw in clinical application.Methods Nine artificial PMMA femoral model were prepared and divided randomly into three groups (n=3),and the specimens were saw up with a hand saw at Pauwels angle of 30° ,50° and 70° in the central neck ,respectively and then fixed with dynamic sleeve three-wing screw.Specimens were fixed at simulated uniped standing position at Instron-8874 servo-hydraulic mechanical testing machine.Linear load of 0~1 200 N was loaded at the rate of 10 mm/min and strains at 11 key points under 1 200 N load were measured,as well as head sink displacement and the strain at principal pressure side and principal tension side under different loads.Results Strengthening peaks were observed at the number six resistance strain gage under the 1 200 N load in all tree groups,and the numerical difference of the three groups was statistically significant(P<0.01).Under the load of 600~1 200 N,head sink displacement compare were performed in each two of the three groups under the same load,respectively,and showed statistically significant difference(P<0.01) ;the strain of principal pressure side and principal tension side of the femoral neck was higher with the increasing Pauwels angle under the same load,the difference was significant(P<0.01).Conclusion With the increasing Pauwel's angle,the shearing force was greater,the contact area of fracture line was smaller,and the fracture was more unstable;in contrast,the shearing force was smaller with the Pauwel's angle smaller,the contact area of fracture line was larger,and the fracture was more stable.%目的 探讨动态套筒式三翼钉治疗股骨颈骨折中的生物力学作用,为临床选择此内固定器治疗股骨颈骨折提供理论依据.方法 利用聚甲基丙烯酸甲酯(PMMA)制作人工股骨模型9

  6. Social inequality and hip fracture

    DEFF Research Database (Denmark)

    Harvey, N. C.; Hansen, L.; Judge, A.

    2015-01-01

    Social inequality appears to be increasing in many countries. We explored whether risk of hip fracture was associated with markers of inequality and whether these relationships changed with time, using data from Danish Health Registries. Methods: All patients 60 years or older with a primary hip...

  7. DYNAMIC HIP ADDUCTION, ABDUCTION AND ABDOMINAL EXERCISES FROM THE HOLMICH GROIN-INJURY PREVENTION PROGRAM ARE INTENSE ENOUGH TO BE CONSIDERED STRENGTHENING EXERCISES - A CROSS-SECTIONAL STUDY

    DEFF Research Database (Denmark)

    Krommes, Kasper; Bandholm, Thomas; Jakobsen, Markus D

    2017-01-01

    BACKGROUND: Training intensity is an important variable in strength training and above 80% of one repetition maximum is recommended for promoting strength for athletes. Four dynamic and two isometric on-field exercises are included in the Hölmich groin-injury prevention study that initially failed...... to show a reduction in groin injuries in soccer players. It has been speculated that exercise-intensity in this groin-injury prevention program was too low to induce the strength gains necessary to protect against groin-related injuries. PURPOSE: To estimate the intensity of the six exercises from...... in the Hölmich groin injury prevention program, except cross-county skiing, is sufficient to be considered strength-training for specific muscle groups in and around the groin region. LEVEL OF EVIDENCE: 3....

  8. 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.

  9. 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.

  10. 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...

  11. 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.

  12. 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:

  13. 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.

  14. 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.

  15. Imaging of neuropathies about the hip

    Energy Technology Data Exchange (ETDEWEB)

    Martinoli, Carlo, E-mail: carlo.martinoli@unige.it [Radiologia – DISC, Università di Genova, Largo Rosanna Benzi 8, I-16132 Genoa (Italy); Miguel-Perez, Maribel [Unit of Human Anatomy and Embryology, Department of Pathology and Experimental Therapy, Faculty of Medicine (C Bellvitge), University of Barcelona, Barcelona (Spain); Padua, Luca [Fondazione Don Gnocchi Onlus and Department of Neurology, Policlinico “A. Gemelli”, Università Cattolica del Sacro Cuore, Rome (Italy); Gandolfo, Nicola [IM2S – Institut Monégasque de Médecine and Chirurgie Sportive, Montecarlo (Monaco); Zicca, Anna [Radiologia – DISC, Università di Genova, Largo Rosanna Benzi 8, I-16132 Genoa (Italy); Tagliafico, Alberto [Radiologia – National Institute for Cancer Research, Genoa (Italy)

    2013-01-15

    Neuropathies about the hip may be cause of chronic pain and disability. In most cases, these conditions derive from mechanical or dynamic compression of a segment of a nerve within a narrow osteofibrous tunnel, an opening in a fibrous structure, or a passageway close to a ligament or a muscle. Although the evaluation of nerve disorders primarily relies on neurological examination and electrophysiology, diagnostic imaging is currently used as a complement to help define the site and aetiology of nerve compression and exclude other disease possibly underlying the patient’ symptoms. Diagnosis of entrapment neuropathies about the hip with US and MR imaging requires an in-depth knowledge of the normal imaging anatomy and awareness of the anatomic and pathologic factors that may predispose or cause a nerve injury. Accordingly, the aim of this article is to provide a comprehensive review of hip neuropathies with an emphasis on the relevant anatomy, aetiology, clinical presentation, and their imaging appearance. The lateral femoral cutaneous neuropathy (meiralgia paresthetica), femoral neuropathy, sciatic neuropathy, obturator neuropathy, superior and inferior gluteal neuropathies and pudendal neuropathy will be discussed.

  16. Stability and robustness of biped passive dynamic robot based on hip mass%基于髋部质量的被动步行机器人稳定性和鲁棒性

    Institute of Scientific and Technical Information of China (English)

    吴晓光; 赵杰; 臧希喆; 朱磊

    2012-01-01

    The effect of upper body on the stable and robust walking of passive dynamic walking robot was researched, based on a compass-gait model which more closely resembled the human walking. The swing stage and the collision stage were modeled by Lagrange method and the principle of angular momentum conservation. Based on the proper description on the basins of attraction of the robot's gait and the detection of the robot's quick disturbance-rejection capabilities to random disturbances, the global stability analysis was combined with the local stability analysis. The initial parameters were configured optimally, and the Proe prototype model was built. The self-regulation of the walking gait under singular or continuous random disturbance was analyzed to obtain the optimized design parameters, thus the actual prototype was produced. The experiment on the actual prototype of dynamic model confirms that any passive dynamic robot with reasonable mass of hips performs more efficient and stable walking gait on a slight slope.%采用一种更接近于人类行走的匀质圆规步态模型,运用Lagrange法和碰撞时刻角动量守恒原理分别建立机器人的摆动模型及碰撞模型.基于对模型步态收敛域与外界扰动快速抑制的准确描述,将全局稳定性分析与局部稳定性分析相结合,对模型进行初始的参数优化配置,并建立Proe样机模型;通过单次与连续外界扰动下不同样机模型步态的自身调节变化分析,最终获得模型参数的最优化配置,并通过实物样机的行走实验进行理论分析验证.仿真结果表明:具有合理髋关节质量的被动步行机器人有更强的行走稳定性与鲁棒性.

  17. Developmental dysplasia of the hip in neonates: evolution of acetabular dysplasia after hip stabilization by brief Pavlik harness treatment.

    Science.gov (United States)

    Bin, K; Laville, J-M; Salmeron, F

    2014-06-01

    The recommended treatment duration in neonates with developmental dysplasia of the hip (DDH) varies depending on whether prolonged Pavlik harness therapy is believed to favourably affect the course of the acetabular dysplasia. According to one theory, several months of additional Pavlik harness therapy after achieving hip reduction contributes to correct the acetabular dysplasia. Another theory holds that hip dislocation induces the acetabular dysplasia, which corrects spontaneously once the femoral head is properly seated in the acetabulum. Here, we evaluated this second theory by studying outcomes after early brief Pavlik harness therapy. Acetabular dysplasia associated with neonatal hip instability undergoes self-correction provided stable hip reduction is achieved very early after birth. Therefore, the duration of Pavlik harness therapy can be substantially shortened. We defined hip instability as either reducible hip dislocation or a very easily dislocatable hip with a soft clunk precluding determination of spontaneous hip position as dislocated or reduced. Static and dynamic ultrasound scans were obtained. Patients with ultrasonographic instability (pubo-femoral distance>5mm with less than 50% of coverage) underwent a second physical examination and received treatment. We re-evaluated 42 abnormal hips in 30 patients after a mean follow-up of 6.7 years (range, 5-14 years). Mean age at treatment initiation was 5 days (range, 1-15 days) and mean treatment duration was 34 days (range, 15-75 days). Mean acetabular angle was 20° (range, 12°-30°) and mean Wiberg's lateral centre-edge angle was 30° (range, 22°-35°). Blunting of the lateral angle of the bony roof was noted in 8 hips at last follow-up. In 1 patient whose hip was stable clinically but unstable by ultrasonography at 21 days of age, recurrent dislocation occurred at 5 months of age. The Severin class was 1a in all patients. Despite continuing controversy about whether hip dislocation induces

  18. Clinical Evaluation of Fused/Ankylosed Hip with Severe Flexion Deformity after Conversion to Total Hip Arthroplasty

    Directory of Open Access Journals (Sweden)

    Saroj Kumar Suwal

    2016-06-01

    Conclusions: THA is an effective treatment for ankylosed hip with severe flexion deformity although complications are noted more than routine hip arthroplasties. Keywords: ankylosed hip; fused hip; severe flexion deformity; total hip arthroplasty. | PubMed

  19. Influence of hooks and a lag screw on internal fixation plates for lateral malleolar fracture: a biomechanical and ergonomic study.

    Science.gov (United States)

    Sakai, Rina; Uchino, Masataka; Yoneo, Terumasa; Ohtaki, Yasuaki; Minehara, Hiroaki; Matsuura, Terumasa; Gomi, Tsutomu; Ujihira, Masanobu

    2017-02-23

    For internal fixation of AO classification Type B lateral malleolar fracture, insertion of lag screws into the fracture plane and fixation with a one-third tubular plate as a neutralization plate are the standard treatment procedures. The one-third tubular plate is processed to a hook shape and hung on the distal end of the fibula. In this study, to compare the function of the hook and lag screws of a one-third tubular plate and LCP for osteosynthesis of lateral malleolar fracture, mechanical indices of internal fixation were compared among the one-third tubular plates with lag screws with and without the hook and a locking compression plate. As mechanical tests, a compression test was performed in which compression in the bone axis direction produced by supporting the body weight was simulated, and a torsion test was performed in which external rotation of the bone axis caused by plantar flexion of the ankle joint was simulated. Muscle strength during walking and the force and torque acting on the ankle and knee joints were determined using inverse dynamic analysis. Finite element analysis was performed to analyze the function of hooks and lag screws. The joint reaction force determined by inverse dynamic analysis was adopted as the loading condition of finite element analysis. A stiffness equivalent to that of healthy bone could be achieved by all three internal fixations. It was clarified that the presence of the hook does not make a difference in stiffness. Displacement of the one-third tubular plate was small regardless of the presence or absence of the hook compared with those of locking compression plates. The presence of the hook did not make any difference in stiffness, suggesting that active preparation of the hook is unnecessary. We also clarified that lag screws inhibit displacement.

  20. Total hip arthroplasty following failed fixation of proximal hip fractures

    Directory of Open Access Journals (Sweden)

    Srivastav Shekhar

    2008-01-01

    Full Text Available Background: Most proximal femoral fractures are successfully treated with internal fixation but a failed surgery can be very distressing for the patient due to pain and disability. For the treating surgeon it can be a challenge to perform salvage operations. The purpose of this study was to evaluate the short-term functional outcome and complications of total hip arthroplasty (THA following failed fixation of proximal hip fracture. Materials and Methods: In a retrospective study, 21 hips in 20 patients (13 females and seven males with complications of operated hip fractures as indicated by either established nonunion or fracture collapse with hardware failure were analysed. Mean age of the patients was 62 years (range 38 years to 85 years. Nine patients were treated for femoral neck fracture, 10 for intertrochanteric (I/T fracture and two for subtrochanteric (S/T fracture of the hip. Uncemented THA was done in 11 cases, cemented THA in eight hip joints and hybrid THA in two patients. Results: The average duration of follow-up was four years (2-13 years. The mean duration of surgery was 125 min and blood loss was 1300 ml. There were three dislocations postoperatively. Two were managed conservatively and one was operated. There was one superficial infection and one deep infection. Only one patient required a walker while four required walking stick for ambulation. The mean Harris Hip score increased from 32 preoperatively to 79 postoperatively at one year interval. Conclusion: Total hip arthroplasty is an effective salvage procedure after failed osteosynthesis of hip fractures. Most patients have good pain relief and functional improvements inspite of technical difficulties and high complication rates than primary arthroplasty.

  1. 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,...

  2. 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...

  3. Biomechanical analysis of titanium fixation plates and screws in ...

    African Journals Online (AJOL)

    Key words: Bone plates, bone screws, finite element analysis, jaw fixation techniques, mandible, mandibular .... model is built up, in similar way to building block construction, .... shows advantages, such as granting intraoral route, minimal.

  4. 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.

  5. Intermaxillary Fixation Screw Morbidity in Treatment of Mandibular Fractures

    DEFF Research Database (Denmark)

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

    2016-01-01

    Surgery, Rigshospitalet, University Hospital of Copenhagen, Copenhagen, Denmark). The fracture type, radiographic findings, treatment modality, screw type and number, and root damage were recorded. For the outcome comparison, a review of the published data regarding iatrogenic dental root damage caused......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...... for IMF of mandibular fractures would result in minimal morbidity. Materials and Methods Patients treated for mandibular fractures from 2007 to 2013, using screws for IMF, using the international diagnosis code for mandibular fracture, DS026, were anonymously selected (Department of Oral and Maxillofacial...

  6. Estimation of hip abduction moment based on body fixed sensors

    NARCIS (Netherlands)

    Zijlstra, W; Bisseling, R

    2004-01-01

    Background During standing and walking, abnormal trunk posture or movements may result from insufficient hip abductor force. Quantifying abduction moments requires inverse dynamics based on an appropriate model and measured data. Contrary to using a force plate and motion analysis system, body fixed

  7. 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.

  8. A Biomimetic Hip Joint Simulator and its Application in in vitro Study of the Integrity of Replacement Cemented Hip

    Institute of Scientific and Technical Information of China (English)

    Liu Chao-zong; S.M.Green; N.D.Watkins; A.W.McCaskie

    2005-01-01

    A biomimetic hip joint simulator that can be used to evaluate the outcome of the cemented total hip replacement has been designed, manufactured and evaluated. The simulator produces motion in the extension/flexion plane, with a socket to rotate internal/externally. At the same time a dynamic loading cycle is applied. A validation test was performed on a cemented femoral stem within a novel composite femur. The bone quality has a strong effect on the stem migration and on the integrity of the interfaces. The migration of the stem is a combination of 3-D translation and rotation of the stem. Under the same loading conditions, weak bone allows more stem migration than strong bone. There is a great decrease in the strength of the stem-cement interface after the dynamic test, and the weak bone composite exhibited a greater reduction in interfacial strength than the strong bone composite. The decrease of the interfacial strength indicates that the primary bonding between the stem and the cement mantle had deteriorated and the integrity of stem-cement interface was damaged.The study demonstrates the value of using a hip joint simulator to investigate stem migration and interface integrity within the cemented hip replacement, suggesting that method can be used for in vitro evaluation of the biomaterials used in the cemented hip replacements.

  9. 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.

  10. Developmental Dislocation (Dysplasia) of the Hip (DDH)

    Science.gov (United States)

    .org Developmental Dislocation (Dysplasia) of the Hip (DDH) Page ( 1 ) The hip is a “ball-and-socket” joint. In a normal hip, the ball at the ... American Academy of Orthopaedic Surgeons. .org Developmental Dislocation (Dysplasia) of the Hip cont. • Family history of DDH (parents or siblings) • ...

  11. 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.

  12. 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.

  13. Bending strength and holding power of tibial locking screws.

    Science.gov (United States)

    Lin, J; Lin, S J; Chiang, H; Hou, S M

    2001-04-01

    The bending strength and holding power of two types of specially designed tibial locking devices, a both-ends-threaded screw and an unthreaded bolt, were studied and compared with four types of commercially available tibial interlocking screws: Synthes, Howmedica, Richards, and Osteo AG. To test bending strength, the devices were inserted into a high molecular weight polyethylene tube and loaded at their midpoint by a materials testing machine to simulate a three point bending test. Single loading yielding strength and cyclic loading fatigue life were measured. To test holding power, the devices were inserted into tubes made of polyurethane foam, and their tips were loaded axially to measure pushout strength. The devices were tested with two different densities of foam materials and two different sizes of pilot holes. Insertion torque and stripping torque of the screws were measured first. Pushout tests were performed with each screw inserted with a tightness equal to 60% of its stripping torque. Test results showed that the yielding strength and the fatigue life were related closely to the inner diameter of the screws. The stripping torque predicted the pushout strength more reliably than did the insertion torque. All tested devices showed greater holding power in the foam with the higher density and with the smaller pilot holes. The both-ends-threaded screw had the highest pushout strength and a satisfactory fatigue strength. The unthreaded bolt had the highest fatigue strength but only fair holding power. Clinical studies of the use of these two types of locking devices are worthwhile.

  14. 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.

  15. 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.

  16. 人工股骨头置换与动力髋螺钉内固定治疗股骨粗隆间骨折的效果比较%Comparison of hip arthroplasty and internal fixation for the treatment of intertrochanteric fractures

    Institute of Scientific and Technical Information of China (English)

    熊秉刚; 谢文伟; 姚汉刚; 利盛成; 廖德允; 李再学; 黎明华; 苏厂尧

    2008-01-01

    Objective To compare the effect of hip artificial replacement and DHS internal fixation for the treatment of intertrochanteric fracture, and investigate the difference of the two method. Methods Eighty-six pa- tients with intertrochanterie fracture patients were treated with hip arthroplasty, and dynamic hip screw. The pa- tients were followed up for 6 months, and compared the operation rime, blood loss, postoperative complications, sur- vival rate, postoperative hip function score and lose situation. Results There was no significant difference in opera- tion time,blood loss,postoperative complications,in local symptoms hip varus deformation occured in the DHS inter- hal fixation because lag screw cut-our and the collapse of the medial cortex, hip and thigh pain oecured in artificial re- placement,hip function score dropped 9.5 % in DHS and 9.2% in artificial replacement. Conclusion For elderly patients, eomminuted fracture and osteoporosis, and other types of unstable intertrochanteric fracture patients, the primary purpose of surgery is to provide to patients more activities of the early conditions,so hip arthroplasty can be used to the treatment of intertrochanteric fracture,as a reasonable replacement surgery.%目的 通过对使用人工股骨头置换与动力髋螺钉(DHs)内固定治疗股骨粗隆间骨折的结果进行比较分析,探讨两者之间的差别.方法 86例高龄股骨粗隆间骨折患者,分别采用人工股骨头置换(半髋组)及DHS内固定方法(DHS组)治疗,经过6个月以上的随访,比较两组患者在手术时间、术中出血、术后并发症、累积生存情况、术后髋部功能评分及丢失情况等方面存在的差异.结果 两组患者在手术时间、术中出血、术后全身并发症等方面无明显差异.局部症状,DHS组出现了内固定穿出骨皮质以及内侧皮质塌陷所造成的髋内翻现象,而半髋组患者则出现髋部及大腿疼痛;DHS组髋关节综合评分下降9.5%,

  17. Canine Hip Dysplasia: Diagnostic Imaging.

    Science.gov (United States)

    Butler, J Ryan; Gambino, Jennifer

    2017-07-01

    Diagnostic imaging is the principal method used to screen for and diagnose hip dysplasia in the canine patient. Multiple techniques are available, each having advantages, disadvantages, and limitations. Hip-extended radiography is the most used method and is best used as a screening tool and for assessment for osteoarthritis. Distraction radiographic methods such as the PennHip method allow for improved detection of laxity and improved ability to predict future osteoarthritis development. More advanced techniques such as MRI, although expensive and not widely available, may improve patient screening and allow for improved assessment of cartilage health. Copyright © 2017 Elsevier Inc. All rights reserved.

  18. Traumatic injuries of the hip.

    LENUS (Irish Health Repository)

    Marshall, Nina

    2009-11-01

    Traumatic lesions of the hip in athletes may be clinically challenging because of the overlap in clinical presentation due to differing pathologies and the presence of multiple injuries. Imaging of the hip in the athlete has undergone a recent resurgence of interest and understanding related to the increasing accessibility and use of hip arthroscopy, which expands the treatment options available for intra-articular pathology. MR imaging and MR arthrography have a unique role in diagnosis of these pathologies, guiding the surgeon, arthroscopist, and referring clinician in their management of bony and soft tissue injury.

  19. Hot Isostatic Pressing (HIP): Techniques, applications and economical use

    Science.gov (United States)

    Bousack, H.

    1985-01-01

    Hot isostatic pressing (HIP) is used to regenerate defect components exposed to dynamic and permanent static loads causing pore formation. It consists in compacting and bonding of powders and solids by encapsulation. The HIP-equipment consists of a high pressure vessel, an oven and a rare gas system for production of isostatic pressure. The compacting procedure using diffusion and deformation processes depends on the pressing temperature. It is used in the production of hard metals, superalloys, fiber composites and ceramic components. It saves energy material and costs.

  20. 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.

  1. 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.

  2. Three-dimensional comparison of alternative screw positions versus actual fixation of scaphoid fractures.

    Science.gov (United States)

    Volk, Ido; Gal, Jonathan; Peleg, Eran; Almog, Gil; Luria, Shai

    2017-06-01

    The recommended technique for the fixation of a scaphoid waist fracture involves a headless compression screw placed in the proximal fragment center. This is usually accomplished by placing a longitudinal axis screw as visualized by fluoroscopy. The screw length has been shown to have a biomechanical advantage. An alternative to these options, which has been debated in the literature, is a screw placed perpendicular to the fracture plane and in its center. The perpendicular screw may have a biomechanical advantage despite the fact that it may be shorter. This study examined the differences in location and length in actual patients between a screw in the center of the proximal fragment with a longitudinal axis screw, and the actual fixating screw. These were then compared to a perpendicular axis screw. Pre- and post-operative CT scans of 10 patients with scaphoid waist fractures were evaluated using a 3D computer model. Comparisons were made between the length, location and angle of actual and virtual screw alternatives; namely, a screw along the central third of the proximal fragment (central screw axis) where the scaphoid longitudinal axis was calculated mathematically (longitudinal screw axis) and a screw placed at 90° to the fracture plane and in its center (perpendicular screw axis). The longitudinal axis screw was found to be significantly longer than the other axes (28.3mm). There was a significant difference between the perpendicular axis screw and the location and angle of the other screw axis, but it was only shorter than the longitudinal screw (23.6mm versus 25.5mm for the actual screw; ns.). A computed longitudinal axis screw is longer than a central or actual screw placed longitudinally by visual inspection by the surgeon. Although it needs to be placed using computer assisted (CAS) techniques, it may have the biomechanical advantages of a longer screw in a similar trajectory. The perpendicular screw was found to be significantly different in position

  3. Editorial Commentary: Helping Those Who Seek the Company of "Lord Stanley": Hockey Players and Hip Injuries Highlight the Current State and Future Challenges in Understanding, Treating, and Preventing Nonarthritic Hip Disease.

    Science.gov (United States)

    Christoforetti, John

    2016-09-01

    The state of the art in caring for athletic hip injuries requires comprehensive understanding of dynamic sport-specific biomechanical demands, accurate musculoskeletal diagnosis, and a mindset towards matching hip structure with functional demand at all levels of play. The sport of hockey presents a unique opportunity to review these fundamentals of modern management and illuminates the way towards future understanding of the cause of common nonarthritic hip conditions.

  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. Biomechanical analysis of pedicle screw density in spinal instrumentation for scoliosis treatment: first results.

    Science.gov (United States)

    Wang, Xiaoyu; Aubin, Carl-Eric; Larson, A Noelle; Labelle, Hubert; Parent, Stefan

    2012-01-01

    Clinical studies reveal remarkable variation in screw patterns, or screw density in spinal instrumentation. Screw density may have a great impact on blood loss, operative time, radiation, risk of screw malposition, and cost. Thus, there is a need to understanding of the biomechanical effects of screw density so as to minimize the number of pedicle screws while ensuring safe and effective instrumentation. The objective of this study was to compare the deformity correction effects and bone-screw loadings of different pedicle screw densities in spinal instrumentation for scoliosis treatment. Spinal instrumentation simulations were performed on three scoliosis patients using 3 screw density patterns (low, preferred, and high screw density) proposed by two experienced surgeons and basic correction techniques: concave rod attachment, rod derotation, apical vertebral derotation, and convex side rod attachment. Simulation results showed that all tested screw densities generated quite similar correction, with differences between the achieved corrections all below 3°. The average bone-screw forces were 244±67N, 214±66 N, and 210±71 N, respectively for low, preferred, and high densities. It remains a complex challenge balancing the benefit of load sharing between more implants with the overconstraints and limited degrees of freedom introduced by the increased number of implants. Studies on additional screw densities and patterns proposed by more surgeons for a variety of cases, and using more diverse correction techniques are necessary to draw stronger conclusions and to recommend the optimal screw density.

  6. 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.

  7. 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

  8. 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.

  9. 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.

  10. Hip dislocation following the treatment of femoral neck fracture: Case report

    Directory of Open Access Journals (Sweden)

    Vukašinović Zoran

    2010-01-01

    Full Text Available Introduction. Femoral neck fractures are very rare in young patients and are frequently complicated by femoral head osteonecrosis and femoral neck nonunion. Case Outline. A 19-year-old girl with hip dislocation following the treatment of the femoral neck fracture is presented. The femoral neck fracture was initially treated by open reduction and three-screw fixation. After detecting the nonunion of femoral neck, valgus osteotomy was done. Secondary, iatrogenic, hip dislocation appeared. The patient had pains, and in clinical findings a shorter leg and limited range of motion in the hip - altogether 40 degrees. She was then successfully treated by open reduction, together with Chiari pelvic osteotomy and joint transfixation. Transfixation pin was removed three weeks following the operation. After that, the patient was put into the abduction device and physical therapy was started. The mentioned regimen lasted four months after the surgery, then the abduction device was removed and walking started. Full weight bearing was allowed eight months after surgery. Conclusion. As we have not found the literature data concerning the above mentioned problem, we solved it in the way that we usually do for the treatment of developmental dislocation of the hip in adolescence.

  11. 3D Printing Aids Acetabular Reconstruction in Complex Revision Hip Arthroplasty

    Directory of Open Access Journals (Sweden)

    Andrew J. Hughes

    2017-01-01

    Full Text Available Revision hip arthroplasty requires comprehensive appreciation of abnormal bony anatomy. Advances in radiology and manufacturing technology have made three-dimensional (3D representation of osseous anatomy obtainable, which provide visual and tactile feedback. Such life-size 3D models were manufactured from computed tomography scans of three hip joints in two patients. The first patient had undergone multiple previous hip arthroplasties for bilateral hip infections, resulting in right-sided pelvic discontinuity and a severe left-sided posterosuperior acetabular deficiency. The second patient had a first-stage revision for infection and recurrent dislocations. Specific metal reduction protocols were used to reduce artefact. The images were imported into Materialise MIMICS 14.12®. The models were manufactured using selective laser sintering. Accurate templating was performed preoperatively. Acetabular cup, augment, buttress, and cage sizes were trialled using the models, before being adjusted, and resterilised, enhancing the preoperative decision-making process. Screw trajectory simulation was carried out, reducing the risk of neurovascular injury. With 3D printing technology, complex pelvic deformities were better evaluated and treated with improved precision. Life-size models allowed accurate surgical simulation, thus improving anatomical appreciation and preoperative planning. The accuracy and cost-effectiveness of the technique should prove invaluable as a tool to aid clinical practice.

  12. 3D Printing Aids Acetabular Reconstruction in Complex Revision Hip Arthroplasty

    Science.gov (United States)

    DeBuitleir, Cathal; Soden, Philip; O'Donnchadha, Brian; Tansey, Anthony; Abdulkarim, Ali; McMahon, Colm; Hurson, Conor J.

    2017-01-01

    Revision hip arthroplasty requires comprehensive appreciation of abnormal bony anatomy. Advances in radiology and manufacturing technology have made three-dimensional (3D) representation of osseous anatomy obtainable, which provide visual and tactile feedback. Such life-size 3D models were manufactured from computed tomography scans of three hip joints in two patients. The first patient had undergone multiple previous hip arthroplasties for bilateral hip infections, resulting in right-sided pelvic discontinuity and a severe left-sided posterosuperior acetabular deficiency. The second patient had a first-stage revision for infection and recurrent dislocations. Specific metal reduction protocols were used to reduce artefact. The images were imported into Materialise MIMICS 14.12®. The models were manufactured using selective laser sintering. Accurate templating was performed preoperatively. Acetabular cup, augment, buttress, and cage sizes were trialled using the models, before being adjusted, and resterilised, enhancing the preoperative decision-making process. Screw trajectory simulation was carried out, reducing the risk of neurovascular injury. With 3D printing technology, complex pelvic deformities were better evaluated and treated with improved precision. Life-size models allowed accurate surgical simulation, thus improving anatomical appreciation and preoperative planning. The accuracy and cost-effectiveness of the technique should prove invaluable as a tool to aid clinical practice. PMID:28168060

  13. Monoarticular Hip Involvement in Pseudogout

    Directory of Open Access Journals (Sweden)

    Figen Kocyigit

    2015-01-01

    Full Text Available Pseudogout is the acutest form of arthritis in the elderly. Although clinical manifestations vary widely, polyarticular involvement is typical mimicking osteoarthritis or rheumatoid arthritis. Monoarticular involvement is relatively rare and is generally provoked by another medical condition. There are reported cases of hip involvement by pseudogout in monoarticular form. However, all of the cases were presented as septic arthritis. In this report, we present a case of monoarticular hip involvement mimicking soft tissue abscess. We confirmed the pseudogout diagnosis after ultrasonographic evaluation of the involved hip joint and pathological and biochemical analysis of synovial fluid analysis. Diagnosis is important to avoid unnecessary medical and surgical treatment in cases of the bizarre involvement of hip in pseudogout.

  14. Abstract: Lightweight Authentication for HIP

    Science.gov (United States)

    Heer, Tobias

    In recent years numerous solutions for overcoming the architectural constraints of the Internet have emerged. One of the most promising among them is the Host Identity Protocol (HIP) [2], which was recently approved as an experimental standard by the IETF. HIP adds an additional protocol layer between TCP and IP to implement the Identifier/Locator split. Apart from mobility and multihoming, HIP supports host authentication, payload encryption, and a cryptographic namespace without requiring changes to the network infrastructure or network applications. However, especially mobile devices with tightly limited CPU resources are slowed down by HIP. Its poor performance on these mobile devices is a result of the extensive use of public-key (PK) cryptography for securing the main protocol functions.

  15. Pullout performance comparison of novel expandable pedicle screw with expandable poly-ether-ether-ketone shells and cement-augmented pedicle screws.

    Science.gov (United States)

    Aycan, Mehmet Fatih; Tolunay, Tolga; Demir, Teyfik; Yaman, Mesut Emre; Usta, Yusuf

    2017-02-01

    Aim of this study is to assess the pullout performance of various pedicle screws in different test materials. Polyurethane foams (Grade 10 and Grade 40) produced in laboratory and bovine vertebrae were instrumented with normal, cannulated (cemented), novel expandable and normal (cemented) pedicle screws. Test samples were prepared according to the ASTM F543 standard testing protocols and surgical guidelines. To examine the screw placement and cement distribution, anteriosuperior and oblique radiographs were taken from each sample after insertion process was completed. Pullout tests were performed in an Instron 3369 testing device. Load versus displacement graphs were recorded and the ultimate pullout force was defined as the maximum load (pullout strength) sustained before failure of screw. Student's t-test was performed on each group whether the differences between pullout strength of pedicle screws were significant or not. While normal pedicle screws have the lowest pullout strength in all test materials, normal pedicle screws cemented with polymethylmethacrylate exhibit significantly higher pullout performance than others. For all test materials, there is a significant improvement in pullout strength of normal screws by augmentation. While novel expandable pedicle screws with expandable poly-ether-ether-ketone shells exhibited lower pullout performance than normal screws cemented with polymethylmethacrylate, their pullout performances in all groups were higher than the ones of normal and cannulated pedicle screws. For all test materials, although cannulated pedicle screws exhibit higher pullout strength than normal pedicle screws, there are no significant differences between the two groups. The novel expandable pedicle screws with expandable poly-ether-ether-ketone shells may be used instead of normal and cannulated pedicle screws cemented with polymethylmethacrylate due to their good performances.

  16. 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.

  17. 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.

  18. Current possibilities for hip arthroplasty,

    Directory of Open Access Journals (Sweden)

    Giancarlo Cavalli Polesello

    2014-04-01

    Full Text Available Hip arthroscopy has been popularized over the last decade and, with technical advances regarding imaging diagnostics, understanding of the physiopathology or surgical techniques, several applications have been described. Both arthroscopy for intra-articular conditions and endoscopy for extra-articular procedures can be used in diagnosing or treating different conditions. This updated article has the objective of presenting the various current possibilities for hip arthroscopy.

  19. Hip: Anatomy and US technique

    OpenAIRE

    2011-01-01

    Ultrasound (US) has always had a relatively limited role in the evaluation of the hip due to the deep location of this joint. However, many hip diseases are well detectable at US, but before approaching such a study it is necessary to be thoroughly familiar with the normal anatomy and related US images. The study technique is particularly important as optimization of various parameters is required, such as probe frequency, focalization, positioning of the probe, etc. Also the patient’s positi...

  20. Conversion of hip arthrodesis to total hip arthroplasty.

    Science.gov (United States)

    Panagiotopoulos, K P; Robbins, G M; Masri, B A; Duncan, C P

    2001-01-01

    With the predictably good outcome now found with THA, hip arthrodesis has limited indications today. The procedure still has a role in the case of the young, heavy demand male with an isolated arthritic hip condition, and developments such as the Cobra head plate have considerably improved success rates. However, a long-term hip arthrodesis can have profound effects on a patient's daily function and activities of daily living. In addition, gait pattern is considerably affected as well as other joints such as the lower back, ipsilateral knee, and contralateral hip. Many patients with a hip arthrodesis will eventually require a takedown of the fused hip and conversion to a THA. The primary indications include fusion in malposition, pseudarthrosis, or severe pain in other joints. The surgeon undertaking such a task must be familiar with the arthrodesis techniques that have been used in the past as well as the equipment that may be required to extract the fixation hardware. Clinical assessment with particular attention to leg-length discrepancy, position of the arthrodesis, and function of the abductors is of paramount importance. The surgeon must carefully review preoperative radiographs to plan the procedure. The surgeon must also be aware of the presence of pathology in other joints. After takedown of a hip arthrodesis and conversion to a THA, patients cannot expect the result to equal the success rates of primary THA. Patients generally can expect an improvement in function and mobility. Back pain and ipsilateral knee pain are usually improved postoperatively, but the effect on contralateral hip pain is less predictable. Many patients will continue to show a positive Trendelenburg sign, but further improvement in strength of the hip abductors can be expected with time. Leg-length discrepancy is generally improved substantially after THA. However, a substantial number of patients will require a walking aid postoperatively. Overall, the risk of complications and the

  1. The biomechanical comparison of original and new dynamic sleeve three-wing screws for femoral neck fracture%改良前后动态套筒式三翼钉固定股骨颈骨折的生物力学比较

    Institute of Scientific and Technical Information of China (English)

    马信龙; 王杰; 王志彬; 马剑雄; 马韬; 杨阳; 徐卫国; 朱少文; 马宝意; 陈阳; 邢丹

    2012-01-01

    Objective To compare the biomechanical property of original and new dynamic sleeve three-wing screws.Methods Twelve artificial polymethylmethacrylate (PMMA) femoral models and twelve adult cadaver femurs were selected,and then adduction-type femoral neck fracture models were prepared.The specimens were divided randomly into 2 groups,and each group had 6 specimens.According to the operative approach,the fractures were fixed with original dynamic sleeve three-wing screw (DSTS) or new DSTS after anatomic reduction.Then the specimens were fixed in simulated uniped standing position with an instron-8874 servo-hydraulic mechanical testing machine.Ten key points at the proximal femurs and two key points at the femoral shaft were selected to be the positions at which the strain was recorded.The continuous load (PMMA group:0-1200 N; cadaver femur group:0-800 N) was put to the specimens at the rate of 10 mm/min.The strain values under the maximum load,the femoral head sinking displacement and the strain values of No.8 gauge under different loads were recorded.Results There was a peak at the No.8 resistance strain gauge under 1200 N in PMMA group,and the strain values of original and new DSTS were (-2744±35) and (-718±14) με,respectively.There was a peak at the No.8 resistance gauge under 800N in cadaver femur group,and the strain values of original and new DSTS were (-2813±38) and (-2032±22) με,respectively.The differences of strain values above were significant.The femoral head sinking displacement of the new DSTS was much less than that of original DSTS under the same load.Conclusion The new DSTS has better biomechanical properties,using which the femoral neck fracture can be fixed more stably.%目的 比较动态套筒式三翼钉改良前后的生物力学性能.方法 采用聚甲基丙烯酸甲酯(polymethyl methacrylate,PMMA)制作人工股骨模型12根,收集成人尸体股骨12根,制备内收型股骨颈骨折模型.均随机分为两组,每组6根标本.

  2. Interpolating gain-scheduled H∞ loop shaping design for high speed ball screw feed drives.

    Science.gov (United States)

    Dong, Liang; Tang, WenCheng; Bao, DaFei

    2015-03-01

    This paper presents a method to design servo controllers for flexible ball screw drives with time-varying dynamics, which are mainly due to the time-varying table position and the workpiece mass. A gain-scheduled H∞ loop shaping controller is designed to achieve high tracking performance against the dynamic variations. H∞ loop shaping design procedure incorporates open loop shaping by a set of compensators to obtain performance/robust stability tradeoffs. The interpolating gain-scheduled controller is obtained by interpolating the state space model of the linear time-invariant (LTI) controllers estimated for fixed values of the scheduling parameters and a linear least squares problem can be solved. The proposed controller has been compared with P/PI with velocity and acceleration feedforward and adaptive backstepping sliding mode control experimentally. The experimental results indicate that the tracking performance has been improved and the robustness for time-varying dynamics has been achieved with the proposed scheme.

  3. 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.

  4. Ipsilateral fracture dislocations of the hip and knee joints with contralateral open fracture of the leg: a rare case and its management principles

    Directory of Open Access Journals (Sweden)

    Sen Ramesh Kumar

    2011-06-01

    Full Text Available 【Abstract】This paper discussed the injury mecha- nism and management of a patient who had concomitant ipsilateral hip and knee dislocations and contralateral open leg fracture. A 32-year-old man presented with ipsilateral fracture- dislocations of the left hip (Pipkin’s type IV and knee (Moore II joints and contralateral open fracture of the leg bones after a car accident. After emergency resuscitative measures, the hip joint was reduced and Pipkin’s fracture was fixed using Ganz approach with lag screws; knee joint was reduced closely and tibial plateau fracture was stabi- lized with lateral buttress plate and a transarticular span- ning fixator. The open fracture on the other leg was de- brided and fixed with an external fixator. There was no insta- bility in both joints after fixation when he was examined under anesthesia. The fractures united after 3 months and the patient had no residual instability of hip and knee. There was no clinical or radiological evidence of osteonecrosis in the hip joint after 6 months. At one-year follow-up, he had satisfactory functional outcome with almost normal range of motion at both joints. Ipsilateral hip and knee dislocations are rare injuries and more caution is needed for early diagnosis. A timely appro- priate intervention can provide good functional outcome to the patient in this situation. Key words: Hip dislocation; Knee dislocation; Fractures, bone

  5. Results of hip resurfacing

    Science.gov (United States)

    Favetti, Fabio; Casella, Filippo; Papalia, Matteo; Panegrossi, Gabriele

    2011-01-01

    Background The renewed popularity of resurfacing hip arthroplasty in the last 10 years has generated a remarkable quantity of scientific contributions based on mid- and short-term follow-up. More than one paper has reported a consistent early revision rate as a consequence of biological or biomechanical failure. Two major complications are commonly described with resurfacing implants: avascular necrosis and femoral-neck fracture. A close relationship between these two events has been suggested, but not firmly demonstrated, whereas cementing technique seems to be better understood as potential cause of failure. Methods We performed an in vitro study in which four different resurfacing implants were evaluated with a simulated femoral head, two types of cement, (low and high viscosity) and two cementing techniques: direct (cement apposition directly on the femoral head) and indirect (cement poured into the femoral component). Results High-viscosity cement showed homogeneous distribution over the entire femoral head. Low-viscosity cement showed a massive polar concentration with insufficient, if not absent, distribution in the equatorial zone. Conclusion Polar cement concentration could be a risk factor for early implant failure due to two effects on the femoral head: biological (excessive local exothermic reaction could cause osteocyte necrosis) and biomechanical (which could lead to uneven load distribution on the femoral head). PMID:21234563

  6. CURBSIDE CONSULTATION IN HIP ARTHROPLASTY

    Directory of Open Access Journals (Sweden)

    Scott M. Sporer

    2009-03-01

    Full Text Available DESCRIPTION A user friendly reference for decision making in hip arthroplasty designed in a question formed clinical problem scenarios and answers format .The articles composed of the answers, containing current concepts and preferences of experts in primary and revision hip surgery are enhanced by several images, diagrams and references and written in the form of a curbside consultation by Scott M. Sporer, MD. and his collaborators. PURPOSE By this practical reference of hip arthroplasty, Scott M. Sporer, MD. and the contributors have aimed providing the reader practical and clinically relevant information, evidence-based advices, their preferences and opinions containing current concepts for difficult and controversial clinical situations in total hip replacement surgery which are often not addressed clearly in traditional references. FEATURES The book is composed of 9 sections and 49 articles each written by a different expert designed in a question and answers format including several images and diagrams and also essential references at the end of each article. In the first section preoperative questions is subjected. Second section is about preoperative acetabulum questions. Third section is about preoperative femur questions. Fourth section is about intraoperative questions. Intraoperative acetabulum question is subjected in the fifth section and the intraoperative femur questions in the sixth section. The seventh section is about postoperative questions. Eighth and ninth sections are about general questions about failure and failure of acetabulum in turn. AUDIENCE Mainly practicing orthopedic surgeons, fellows and residents who are interested in hip arthroplasty have been targeted but several carefully designed scenarios of controversial and difficult situations surrounding total hip replacement surgery and the current information will also be welcomed by experienced clinicians practicing in hip arthroplasty. ASSESSMENT Scott M. Sporer

  7. Preoperative CT planning of screw length in arthroscopic Latarjet.

    Science.gov (United States)

    Hardy, Alexandre; Gerometta, Antoine; Granger, Benjamin; Massein, Audrey; Casabianca, Laurent; Pascal-Moussellard, Hugues; Loriaut, Philippe

    2016-08-25

    The Latarjet procedure has shown its efficiency for the treatment of anterior shoulder dislocation. The success of this technique depends on the correct positioning and fusion of the bone block. The length of the screws that fix the bone block can be a problem. They can increase the risk of non-union if too short or be the cause of nerve lesion or soft tissue discomfort if too long. Suprascapular nerve injuries have been reported during shoulder stabilisation surgery up to 6 % of the case. Bone block non-union depending on the series is found around 20 % of the cases. The purpose of this study was to evaluate the efficiency of this CT preoperative planning to predict optimal screws length. The clinical importance of this study lies in the observation that it is the first study to evaluate the efficiency of CT planning to predict screw length. Inclusion criteria were patients with chronic anterior instability of the shoulder with an ISIS superior to 4. Exclusion criteria were patients with multidirectional instability or any previous surgery on this shoulder. Thirty patients were included prospectively, 11 of them went threw a CT planning, before their arthroscopic Latarjet. Optimal length of both screws was calculated, adding the size of the coracoid at 5 and 15 mm from the tip to the glenoid. Thirty-two-mm screws were used for patients without planning. On a post-operative CT scan with 3D reconstruction, the distance between the screw tip and the posterior cortex was measured. A one-sample Wilcoxon test was used to compare the distance from the tip of the screw to an acceptable positioning of ±2 mm from the posterior cortex. In the group without planning, screw 1 tended to differ from the acceptable positioning: mean 3.44 mm ± 3.13, med 2.9 mm, q1; q3 [0.6; 4.75] p = 0.1118, and screw 2 differed significantly from the acceptable position: mean 4.83 mm ± 4.11, med 3.7 mm, q1; q3 [1.7; 5.45] p = 0.0045. In the group with planning, position of

  8. 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.

  9. Pediatric lumbar pedicle screw placement using navigation templates: A cadaveric study

    Directory of Open Access Journals (Sweden)

    Xing Wang

    2017-01-01

    Full Text Available Background: Pedicle screw technique is commonly used treatment of adult spinal trauma, tumor, degeneration. The application of pedicle screws is very challenging in children because children have a fast growing spine and spinal pedicle morphology of children and adult has large difference. 3 D reconstruction individual navigation templates improve the success rate of pediatric pedicle screw system. This study is aimed to provide a precise method for lumbar spine pedicle screw placement in children using computer-aided design and rapid prototyping technology. Materials and Methods: Computed tomography (CT scans of cadaver specimens of 4 children were obtained, and the raw data were reconstructed using three-dimensional reconstruction software. Pedicle screws were placed using the conventional method or by using individually designed navigation templates based on the principles of reverse engineering and rapid prototyping technology. Results: We evaluated the accuracy of the pedicle screws placed using the two methods by CT scan. Ten navigation templates were designed for placement of 20 lumbar pedicle screws in the navigation group, and CT scan confirmed that all the screws were placed accurately in the corresponding pedicle. Conversely, of the 20 lumbar pedicle screws placed using the conventional method, 3 screws perforated the pedicle. The findings showed that lumbar pedicle screw placement was successful using navigation templates in children. Conclusions: This technique is simple, easy to master, and allows personalized screw placement, thus providing a new and feasible method for lumbar pedicle screw placement in children.

  10. 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.

  11. Anatomic considerations of costotransverse screw placement in the thoracic spine.

    Science.gov (United States)

    Xu, R; Ebraheim, N A; Ou, Y; Skie, M; Yeasting, R A

    2000-04-01

    Numerous techniques have been reported to restore spinal stability and to correct spinal deformities, including rods with wires/hooks, and rods or plates with pedicular screws. It was thought that posterior fixation of the thoracic spine through the costotransverse joint may be another alternative. Nine cadavers were obtained for study of screw fixation of the costotransverse joint for posterior thoracic instrumentation. The entrance point for screw insertion was designed to be at the posterior center of the clubbed extremity of the transverse process. From this point, a 3-mm drill bit was used to create the screw path penetrating the costotransverse joint and the ventral cortex of the rib. Under direct visualization of the costotransverse joint, the drill bit was directed parallel to the sagittal plane and toward the upper portion of the rib. Measurements included the screw path length and sagittal angulation. Also, the distance between the superior borders of the transverse process and the tubercle of the rib and the anatomic relationship of the drill bit exit to the intercostal vessels and nerves were evaluated. The maximum length of the screw path was found at T1 (19.7 mm), whereas the minimum length was noted at T4-T5 (13.9 mm). This value decreased gradually from T1 to T4-T5, and slightly increased to T10. The larger sagittal angles of the screw path were found at the levels of T1-T4 (78-86 degrees ), whereas the smaller were noted at the levels below T5 (53-61 degrees ). The mean distance between the superior borders of the transverse process and the tubercle of the rib was smaller at T1-T5 (0.2-0.4 mm), and significantly increased to T8 (5. 1 mm), and then slightly decreased to T10. The variation of this parameter was remarkable. All of the exit points for the drill bit were located in the upper half of the rib, and away from the intercostal vessels. The ideal screw orientation is parallel to the sagittal plane, and angled 80-90 degrees relative to the

  12. Salvage of failed osteosynthesis of an intracapsular fracture of the femoral neck using two cannulated compression screws and a vascularised iliac crest bone graft.

    Science.gov (United States)

    Xiaobing, Y; Dewei, Z

    2015-07-01

    We evaluated the outcome of treatment of nonunion of an intracapsular fracture of the femoral neck in young patients using two cannulated screws and a vascularised bone graft. A total of 32 patients (15 women and 17 men, with a mean age of 36.5 years; 20 to 50) with failed internal fixation of an intracapsular fracture were included in the study. Following removal of the primary fixation, two cannulated compression screws were inserted with a vascularised iliac crest bone graft based on the ascending branch of the lateral femoral circumflex artery. At a mean follow-up of 6.8 years (4 to 10), union was achieved in 27 hips (84%). A total of five patients with a mean age of 40.5 years (35 to 50) had a persistent nonunion and underwent total hip arthroplasty as also did two patients whose fracture united but who developed osteonecrosis of the femoral head two years post-operatively. Statistical analysis showed that younger patients achieved earlier and more reliable union (p 45 years (p osteosynthesis of a displaced intracapsular fractures of the femoral neck has failed.

  13. 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.

  14. 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.

  15. 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.

  16. Theoretical investigation of flash vaporisation in a screw expander

    Science.gov (United States)

    Vasuthevan, Hanushan; Brümmer, Andreas

    2017-08-01

    In the present study flash vaporisation of liquid injection in a twin screw expander for a Trilateral Flash Cycle (TFC) is examined theoretically. The TFC process comprises a pressure increase in the working fluid, followed by heating the liquid close to boiling point. The hot liquid is injected into the working chamber of a screw expander. During this process the pressure of the liquid drops below the saturation pressure, while the temperature of the liquid remains virtually constant. Hence the liquid is superheated and in a metastable state. The liquid jet seeks to achieve a stable state in thermodynamic equilibrium and is therefore partially vaporised. This effect is referred to as flash vaporisation. Accordingly, a two-phase mixture, consisting of vapour and liquid, exists in the working chamber. Thermodynamic simulations were carried out using water as the working fluid for representative screw expander geometry. The simulations presented are performed from two different aspects during the filling process of a screw expander. The first case is the vaporisation of the injected liquid in a state of thermodynamic equilibrium, whereby the two-phase mixture is treated entirely as a compressible and homogeneous gas. The second case considers flashing efficiency. It describes the quantity of flashed vapour and consists of a liquid and vapour domain. Both models are compared and analysed with respect to the operational behaviour of a screw expander.

  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. 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.

  19. Osteochondritis Dissecans of the Hip

    Energy Technology Data Exchange (ETDEWEB)

    Linden, B. [Hoeglands Hospital, Eksjoe (Sweden). Dept. of Orthopedic Surgery; Jonsson, K. [Univ. Hospital, Lund (Sweden). Center for Medical Imaging and Physiology; Redlund-Johnell, I. [Univ. Hospital, Malmoe (Sweden). Dept. of Diagnostic Radiology

    2003-03-01

    Purpose: To investigate the clinical and radiological characteristics of osteochondritis dissecans (OD) of the hip and the outcome of this condition after treatment. Material and Methods: Twelve male and 3 female patients with OD were retrospectively studied. Six patients had a history of Legg-Calve-Perthes disease (LCPD) and among them 2 also had had a trauma to the hip. A further 5 had had trauma and 1 a developmental dislocation of the hip (DDH). The remaining 3 patients had no history of previous hip disease or trauma. All patients were examined with plain radiography, 7 with MR, 3 with CT and 2 with hip arthrography. Results: All OD lesions were detected at plain radiography, and most of them were located near the fovea. At MR the lesions had low signal intensity at T1-weighted sequences, and 6/7 had edema or fluid collection in or adjacent to the lesion on T2-weighted sequences. The early treatment in 7 patients was surgery, 2 had had conservative treatment and 6 no treatment. At follow-up 12 years after radiological diagnosis, 5 patients had hip arthrosis, 4 of whom were treated with arthroplasty. All but 3 had reduced hip rotation and all but 2 (with arthroplasty) had load pain. Three of the patients with earlier surgery had not developed arthrosis. Conclusions: OD lesions are usually well seen with plain radiography. There is a great risk of developing early arthrosis and it seems that early surgery is connected with arthrosis development. Thus only symptomatic treatment is recommended.

  20. Understanding of edge and screw dislocations in nanostructures by modeling and simulations

    Science.gov (United States)

    Dontsova, Evgeniya

    The role of the extended dislocation defects in nanostructures only recently began to be explored. In bulk materials, dislocations are modeled only away from their cores within the framework of the continuum mechanics. It is known that applying continuum modeling in the core region leads to divergences. In nanostructures, the core region dominates and new investigation methods are needed. This work contributes to the fundamental understanding of the role of dislocations in important carbon and zinc oxide nanostructures, by using atomistic investigation methods. In quasi-zero-dimensional structures, thesis describes the first attempt to rationalize dislocation processes in carbon nano-onions. Experiments show that carbon nano-onions exhibit an unusual dislocation dynamics with unexpected attraction of outer edge dislocation towards the core. Atomistic calculations combined with rigorous energy analysis attribute this behavior to an unusual inward driving force on the outer edge dislocation associated with a reduction in the number of dangling bonds. Moving on to quasi-one-dimensional nanostructures, we study the stability of screw-dislocated zinc oxide structures in the wurtzite phase with a symmetry-adapted molecular dynamics methodology, which introduces a significant simplification in the simulation domain size by accounting for the helical symmetry explicitly. The goal is to provide the theoretical support for a universal screw-dislocation-driven growth mechanism suggested by recent experiments. Moreover, the effects of axial screw dislocations on the electronic properties in helical zinc oxide nanowires and nanotubes are explored. We demonstrate significant screw-dislocation-induced band gap modifications that originate in the highly distorted cores. Finally, using the same objective technique, we investigate the stability against torsional deformations of quasi-one-dimensional graphene nanoribbons with bare, F-, and OH-saturated armchair edges. The prevalence

  1. Emerging topics on the hip: Ligamentum teres and hip microinstability

    Energy Technology Data Exchange (ETDEWEB)

    Cerezal, Luis, E-mail: lcerezal@gmail.com [Diagnóstico Médico Cantabria, C/Castilla 6, 39002 Santander (Spain); Arnaiz, Javier; Canga, Ana; Piedra, Tatiana [Valdecilla University Hospital, 39011 Santander (Spain); Altónaga, José R. [Leon University, 24071 Leon (Spain); Munafo, Ricardo [CETEA, Buenos Aires (Argentina); Pérez-Carro, Luis [Valdecilla University Hospital, 39011 Santander (Spain)

    2012-12-15

    Microinstability and ligament teres lesions are emergent topics on the hip pathology. These entities are an increasingly recognized cause of persistent hip pain and should be considered in the differential diagnosis of the patient with hip pain. Conventional (non-arthrographic) CT and MR have a very limited role in the evaluation of these entities. CTa and MRa have emerged as the modalities of choice for pre-operative imaging of ligamentum teres injuries and microinstability. To date, pre-operative imaging detection of these pathologies is not widespread but with appropriate imaging and a high index of suspicion, preoperative detection should improve. This article discusses current concepts regarding anatomy, biomechanics, clinical findings, diagnosis and treatment of ligament teres lesions and microinstability.

  2. Influence of bacterial colonization of the healing screws on peri-implant tissue

    Directory of Open Access Journals (Sweden)

    Simonetta D'Ercole

    2013-06-01

    Conclusion: The healing screws left in situ for a period of 90 days caused a peri-implant inflammation and the presence of periodontal pathogenic bacteria in the peri-implant sulcus, due to the plaque accumulation on screw surfaces.

  3. Adaptive backstepping sliding mode control of flexible ball screw drives with time-varying parametric uncertainties and disturbances.

    Science.gov (United States)

    Dong, Liang; Tang, Wen Cheng

    2014-01-01

    This paper presents a method to model and design servo controllers for flexible ball screw drives with dynamic variations. A mathematical model describing the structural flexibility of the ball screw drive containing time-varying uncertainties and disturbances with unknown bounds is proposed. A mode-compensating adaptive backstepping sliding mode controller is designed to suppress the vibration. The time-varying uncertainties and disturbances represented in finite-term Fourier series can be estimated by updating the Fourier coefficients through function approximation technique. Adaptive laws are obtained from Lyapunov approach to guarantee the convergence and stability of the closed loop system. The simulation results indicate that the tracking accuracy is improved considerably with the proposed scheme when the time-varying parametric uncertainties and disturbances exist.

  4. Numerical study on mixing performance of glass fiber dispersion in a twin-screw extruder with backward-mixing elements

    Science.gov (United States)

    Hirata, Kunihiro; Ishida, Hiroshi; Hiragori, Motohiro; Nakayama, Yasuya; Kajiwara, Toshihisa

    2015-05-01

    In the kneading of glass-fiber-reinforced plastics by twin-screw extrusion, the use of a backward-mixing screw (BMS) element for melt mixing has been found to be effective in dispersing glass-fiber bundles. In this study, we use the computational fluid dynamics (CFD) to study the mechanism of dispersion by a BMS element for glass fiber bundles. The result of CFD for a BMS and a forward kneading disk (FKD) reveals that the melt mixing by a BMS is highly effective to act the required stress on overall resin. In addition, there is a good correlation between the incidence of undispersed glass-fiber bundles measured experimentally and the minimum value of distribution of the time-integrated stress calculated numerically. On the basis of the above results, we propose a method to predict the operating conditions in which the incident probability of undispersed glass-fiber bundles and thermal degradation are controlled.

  5. Curved Periacetabular Osteotomy for the Treatment of Dysplastic Hips

    Science.gov (United States)

    Nakamura, Yoshinari

    2014-01-01

    Curved periacetabular osteotomy (CPO) was developed for the treatment of dysplastic hips in 1995. In CPO, the exposure of osteotomy sites and osteotomy of the ischium are made in the same manner as Bernese periacetabular osteotomy, and iliac and pubic osteotomies are performed in the same manner as rotational acetabular osteotomy. We studied the dynamic instabilities of 25 dysplastic hips before and after CPO using triaxial accelerometry. Overall magnitude of acceleration was significantly decreased from 2.30 ± 0.57 m/sec2 preoperatively to 1.55 ± 0.31 m/sec2 postoperatively. Pain relief and improvement of acetabular coverage resulting from acetabular reorientation seem to be related with reduction of dynamic instabilities of dysplastic hips. Isokinetic muscle strengths of 24 hips in 22 patients were measured preoperatively and after CPO. At 12 months postoperatively, the mean muscle strength exceeded the preoperative values. These results seem to be obtained due to no dissection of abductor muscles in CPO. The preoperative presence of acetabular cysts did not influence the results of CPO. An adequate rotation of the acetabular fragment induced cyst remodeling. Satisfactory results were obtained clinically and radiographically after CPO in patients aged 50 years or older. CPO alone for the treatment of severe dysplastic hips classified as subluxated hips of Severin group IV-b with preoperative CE angles of up to -20° could restore the acetabular coverage, weight-bearing area and medialization of the hip joint. CPO without any other combined procedure, as a treatment for 17 hips in 16 patients with Perthes-like deformities, produced good mid-term clinical and radiographic results. We have been performing CPO in conjunction with osteochondroplasty for the treatment of acatabular dysplasia associated with femoroacetabular impingement since 2006. The combined procedure has been providing effective correction of both acetabular dysplasia and associated femoral head

  6. Developmental dysplasia of the hip

    Directory of Open Access Journals (Sweden)

    Shahryar Noordin

    2010-10-01

    Full Text Available Developmental dysplasia of the hip (DDH is a spectrum of anatomical abnormalities of the hip joint in which the femoral head has an abnormal relationship with the acetabulum. Most studies report an incidence of 1 to 34 cases per 1,000 live births and differences could be due to different diagnostic methods and timing of evaluation. Risk factors include first born status, female sex, positive family history, breech presentation and oligohydramnios. Clinical presentations of DDH depend on the age of the child. Newborns present with hip instability, infants have limited hip abduction on examination, and older children and adolescents present with limping, joint pain, and/or osteoarthritis. Repeated, careful examination of all infants from birth and throughout the first year of life until the child begins walking is important to prevent late cases. Provocative testing includes the Barlow and Ortolani maneuvers. Other signs, such as shorting of the femur with hips and knees flexed (Galeazzi sign, asymmetry of the thigh or gluteal folds, and discrepancy of leg lengths are potential clues. Treatment depends on age at presentation and outcomes are much better when the child is treated early, particularly during the first six months of life.

  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. Initial experience with a newly developed cementless hip endoprosthesis.

    Science.gov (United States)

    Hach, V; Delfs, G

    2009-01-01

    The HELICA-Endoprosthesis is a newly developed cementless hip prosthesis for dogs. It was implanted in 39 dogs that had severe hip osteoarthritis and a history of hip pain, as well as in one dog that had chronic hip luxation. One dog had a bilateral arthroplasty. The body weight of the patients ranged between 22 and 54 kg and their ages between nine months and 10 years. Both the femoral stem and acetabular component of the prosthesis were screwed into position following bony preparation. Additional fixation was not necessary as the components remain fixed in position until osteointegration is complete. There are currently five sizes of prosthesis available, and the various components such as the stem, cup and head are readily interchangeable. Although it appeared that good osseous anchorage of the prostheses in the bone on the surgery table had been obtained, three patients experienced both stem and cup loosening (one week, three weeks and six months after surgery). In one animal, stem loosening was observed six weeks after surgery, and another dog experienced a cup loosening two weeks postoperatively. Most of the complications were due to technical errors that occurred during the learning phase. Surgical revisions were successful in three out of five animals. In two animals we had to perform a femoral head and neck excision. Two other animals experienced radiographic bone resorption underneath the segmented collar of the femoral prosthesis but did not show any significant clinical signs of lameness. Another dog that showed signs of ischial neuropraxy after surgery, recovered completely within six weeks after surgery. All of the dogs were capable of weight bearing on the operated leg one day after surgery. The main advantage of the HELICA-Endoprosthesis is the relatively easy surgical technique and short surgery time. The initial clinical results in these 40 cases have been very encouraging. The aim of this study was to assess the early clinical results in these 39

  9. 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.

  10. [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.

  11. 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.

  12. New concept single screw compressors and their manufacture technology

    Science.gov (United States)

    Feng, Q.; Liu, F.; Chang, L.; Feng, C.; Peng, C.; Xie, J.; van den Broek, M.

    2017-08-01

    Single screw compressors were generally acknowledged as one of the nearly perfect machines by compressor researchers and manufacturers. However the rapid wear of the star-wheel in a single screw compressor during operation is a key reason why it hasn’t previously joined the main current compressors’ market. After more than ten years of effective work, the authors of this paper have proposed a new concept single screw compressor whose mesh-couple profile is enveloped with multi-column. Also a new design method and manufacture equipment for this kind of compressor have been developed and are described in this paper. A lot of prototype tests and a long period of industrial operations under full loading conditions have shown that the mesh-couple profiles of the new concept single compressors have excellent anti-wearness.

  13. 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.

  14. Experimental determination of bone cortex holding power of orthopedic screw

    Directory of Open Access Journals (Sweden)

    Bolliger Neto Raul

    1999-01-01

    Full Text Available Cylindrical specimens of bone measuring 15 mm in diameter were obtained from the lateral cortical layer of 10 pairs of femurs and tibias. A central hole 3.2 mm in diameter was drilled in each specimen. The hole was tapped, and a 4.5 mm cortical bone screw was inserted from the outer surface. The montage was submitted to push-out testing up to a complete strip of the bone threads. The cortical thickness and rupture load were measured, and the shear stress was calculated. The results were grouped according to the bone segment from which the specimen was obtained. The results showed that bone cortex screw holding power is dependent on the bone site. Additionally, the diaphyseal cortical bone tissue is both quantitatively and qualitatively more resistant to screw extraction than the metaphyseal tissue.

  15. 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.

  16. 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...

  17. Biomechanical and histological evaluation of roughened surface titanium screws fabricated by electron beam melting.

    Directory of Open Access Journals (Sweden)

    Jun Yang

    Full Text Available BACKGROUND: Various fabrication methods are used to improve the stability and osseointegration of screws within the host bone. The aim of this study was to investigate whether roughened surface titanium screws fabricated by electron beam melting can provide better stability and osseointegration as compared with smooth titanium screws in sheep cervical vertebrae. METHODS: Roughened surface titanium screws, fabricated by electron beam melting, and conventional smooth surface titanium screws were implanted into sheep for 6 or 12 weeks (groups A and B, respectively. Bone ingrowth and implant stability were assessed with three-dimensional imaging and reconstruction, as well as histological and biomechanical tests. RESULTS: No screws in either group showed signs of loosening. Fibrous tissue formation could be seen around the screws at 6 weeks, which was replaced with bone at 12 weeks. Bone volume/total volume, bone surface area/bone volume, and the trabecular number were significantly higher for a define region of interest surrounding the roughened screws than that surrounding the smooth screws at 12 weeks. Indeed, for roughened screws, trabecular number was significantly higher at 12 weeks than at 6 weeks. On mechanical testing, the maximum pullout strength was significantly higher at 12 weeks than at 6 weeks, as expected; however, no significant differences were found between smooth and roughened screws at either time point. The maximum torque to extract the roughened screws was higher than that required for the smooth screws. CONCLUSIONS: Electron beam melting is a simple and effective method for producing a roughened surface on titanium screws. After 12 weeks, roughened titanium screws demonstrated a high degree of osseointegration and increased torsional resistance to extraction over smooth titanium screws.

  18. Biomechanical and histological evaluation of roughened surface titanium screws fabricated by electron beam melting.

    Science.gov (United States)

    Yang, Jun; Cai, Hong; Lv, Jia; Zhang, Ke; Leng, Huijie; Wang, Zhiguo; Liu, Zhongjun

    2014-01-01

    Various fabrication methods are used to improve the stability and osseointegration of screws within the host bone. The aim of this study was to investigate whether roughened surface titanium screws fabricated by electron beam melting can provide better stability and osseointegration as compared with smooth titanium screws in sheep cervical vertebrae. Roughened surface titanium screws, fabricated by electron beam melting, and conventional smooth surface titanium screws were implanted into sheep for 6 or 12 weeks (groups A and B, respectively). Bone ingrowth and implant stability were assessed with three-dimensional imaging and reconstruction, as well as histological and biomechanical tests. No screws in either group showed signs of loosening. Fibrous tissue formation could be seen around the screws at 6 weeks, which was replaced with bone at 12 weeks. Bone volume/total volume, bone surface area/bone volume, and the trabecular number were significantly higher for a define region of interest surrounding the roughened screws than that surrounding the smooth screws at 12 weeks. Indeed, for roughened screws, trabecular number was significantly higher at 12 weeks than at 6 weeks. On mechanical testing, the maximum pullout strength was significantly higher at 12 weeks than at 6 weeks, as expected; however, no significant differences were found between smooth and roughened screws at either time point. The maximum torque to extract the roughened screws was higher than that required for the smooth screws. Electron beam melting is a simple and effective method for producing a roughened surface on titanium screws. After 12 weeks, roughened titanium screws demonstrated a high degree of osseointegration and increased torsional resistance to extraction over smooth titanium screws.

  19. 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

  20. Blocking screws for the treatment of distal femur fractures.

    Science.gov (United States)

    Seyhan, Mustafa; Cakmak, Selami; Donmez, Ferdi; Gereli, Arel

    2013-07-01

    Intramedullary nailing is one of the most convenient biological options for treating distal femoral fractures. Because the distal medulla of the femur is wider than the middle diaphysis and intramedullary nails cannot completely fill the intramedullary canal, intramedullary nailing of distal femoral fractures can be difficult when trying to obtain adequate reduction. Some different methods exist for achieving reduction. The purpose of this study was determine whether the use of blocking screws resolves varus or valgus and translation and recurvatum deformities, which can be encountered in antegrade and retrograde intramedullary nailing. Thirty-four patients with distal femoral fractures underwent intramedullary nailing between January 2005 and June 2011. Fifteen patients treated by intramedullary nailing and blocking screws were included in the study. Six patients had distal diaphyseal fractures and 9 had distal diaphyseo-metaphyseal fractures. Antegrade nailing was performed in 7 patients and retrograde nailing was performed in 8. Reduction during surgery and union during follow-up were achieved in all patients with no significant complications. Mean follow-up was 26.6 months. Mean time to union was 12.6 weeks. The main purpose of using blocking screws is to achieve reduction, but they are also useful for maintaining permanent reduction. When inserting blocking screws, the screws must be placed 1 to 3 cm away from the fracture line to avoid from propagation of the fracture. When applied properly and in an adequate way, blocking screws provide an efficient solution for deformities encountered during intramedullary nailing of distal femur fractures. Copyright 2013, SLACK Incorporated.

  1. 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

  2. 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

  3. [Uncemented arthroplasty of the hip].

    Science.gov (United States)

    von Schulze Pellengahr, C; Fottner, A; Utzschneider, S; Schmitt-Sody, M; Teske, W; Lichtinger, T; Esenwein, S A

    2009-05-01

    Prognosis of cemented total hip replacement seems to be excellent for elderly patients. In younger age the outcome is less favourable and early revision is more common. Thus, different concepts with better prognosis and preservation of bone stock for possible revisions were needed. After more than 30 years of application with excellent short-term and long-term results, uncemented total hip arthroplasty is nowadays generally regarded as the standard procedure for younger patients. New bone-preserving implants, such as surface replacement or short-stemmed femoral shaft prostheses, have been introduced especially for younger patients. Some of these new procedures are still under development, and the long-term results of new implant concepts have to be evaluated over the next decades. Regarding recently published scientific studies an overview about non-cemented total hip arthroplasty is given and current concepts and developments are presented.

  4. Cementless Hydroxyapatite Coated Hip Prostheses

    Directory of Open Access Journals (Sweden)

    Antonio Herrera

    2015-01-01

    Full Text Available More than twenty years ago, hydroxyapatite (HA, calcium phosphate ceramics, was introduced as a coating for cementless hip prostheses. The choice of this ceramic is due to its composition being similar to organic apatite bone crystals. This ceramic is biocompatible, bioactive, and osteoconductive. These qualities facilitate the primary stability and osseointegration of implants. Our surgical experience includes the implantation of more than 4,000 cementless hydroxyapatite coated hip prostheses since 1990. The models implanted are coated with HA in the acetabulum and in the metaphyseal area of the stem. The results corresponding to survival and stability of implants were very satisfactory in the long-term. From our experience, HA-coated hip implants are a reliable alternative which can achieve long term survival, provided that certain requirements are met: good design selection, sound choice of bearing surfaces based on patient life expectancy, meticulous surgical technique, and indications based on adequate bone quality.

  5. Radiology of the resurfaced hip

    Energy Technology Data Exchange (ETDEWEB)

    Rahman, Luthfur [The London Hip Unit, London (United Kingdom); Hall-Craggs, Margaret [University College London Hospital, London (United Kingdom); Muirhead-Allwood, Sarah K. [The London Hip Unit, London (United Kingdom); The Royal National Orthopaedic Hospital, Middlesex (United Kingdom)

    2011-07-15

    Hip resurfacing arthroplasty is an increasingly common procedure for osteoarthritis. Conventional radiographs are used routinely for follow-up assessment, however they only provide limited information on the radiological outcome. Various complications have been reported in the scientific literature although not all are fully understood. In an effort to investigate problematic or failing hip resurfacings, various radiological methods have been utilized. These methods can be used to help make a diagnosis and guide management. This paper aims to review and illustrate the radiographic findings in the form of radiography, computerized tomography (CT), magnetic resonance imaging (MRI), and ultrasound of both normal and abnormal findings in hip resurfacing arthroplasty. However, imaging around a metal prosthesis with CT and MRI is particularly challenging and therefore the potential techniques used to overcome this are discussed. (orig.)

  6. Developmental hip dysplasia in adolescence

    Directory of Open Access Journals (Sweden)

    Vukašinović Zoran

    2009-01-01

    Full Text Available The authors define adolescence and developmental dysplasia of the hip (DDH. Special attention is paid to pathological findings characteristic of DDH in adolescence (unrecognized and untreated DDH; treated DDH, but non-terminated treatment; DDH diagnosed with delay, inadequately treated, with complications. The authors emphasise that DDH treatment has to be successfully terminated well before the adolescence; possibilities are explained on management modes at the time of adolescence, and possible persons guilty for the persistence of later hip problems are indicated. Based on the authors' experience and having in mind all surgical possibilities for the treatment (pelvic osteotomies, femoral osteotomies, trochanteroplasties, leg length equalization procedures the authors propose treatment protocols. The intention is to provide better treatment results and to prevent secondary hip arthrosis. Furthermore, how to improve the struggle against DDH is suggested.

  7. 股骨颈自锁钉板系统的研制及其生物力学结构测试%Design and biomechanical structure evaluation of self-locking screw plate system for femoral neck fracture

    Institute of Scientific and Technical Information of China (English)

    昌耘冰; 尹东; 李凭跃

    2004-01-01

    combines plate and screw through self-locking mechanism to form a stable mechanical structure inside the femoral neck, which can effectively antagonize the nocuous stress to fractured femoral neck.%背景:应用于股骨颈骨折的内固定器材种类繁多,但均存在较多的生物力学缺陷.目的:研制应用于股骨颈骨折的新型内固定器械并了解其生物力学特性.设计:随机对照的开放性实验.地点和对象:在第一军医大学生物力学重点实验室进行,12具新鲜人尸体股骨干标本为测试材料.干预:根据股骨颈骨折的病理和生物力学特点,设计由主钉,辅钉,自锁钢板组成的钉板系统(self-locking screw plate system,SLSP).分4组进行生物力学比较测试:①SLSP.②3枚空心加压钉(three compressive screws,TCS).③Hansson钉(Hansson pin,HP).④动力髋螺钉(Dynamic hip screw,DHS).主要观察指标:不同组内固定后股骨头的下沉位移(刚度)、水平位移(刚度)以及抗扭转强度和极限载荷.结果:上述4组固定在600 N纵向载荷时的下沉位移分别为:(4.25±0.20),(5.58±0.41),(5 87±0.35),(6.40±0.43)mm.水平位移分别为:(1.78±0.25),(2.41±0 04),(2.42±0.25),(2.79±0.31)mm.SLSP与各组之间均存在统计学差异(P<0.01).取等量扭矩1 N·m时的扭角比较,SLSP组的扭角分别较TCS组、HP组和DHS组小15%,35%和43%,差异有显著性意义(F=96.7,P<0.01).SLSP的极限载荷和位移分别为(3 830±66)N和(7.49±1.2)mm,其极限载荷明显高于其他3组.结论:采用SLSP系统进行股骨颈骨折内固定后,股骨头在下沉位移(刚度)、水平位移(刚度)以及抗扭转强度和极限载荷均高于其他3种固定形式.股骨颈自锁钉板系统通过自锁机制将钢板和螺钉两者有机地结合在一起,在股骨颈内构成稳定的力学结构,能有效地对抗股骨颈骨折后的有害应力.

  8. 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.

  9. 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 §...

  10. 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.

  11. Hip dysplasia in the skeletally mature patient

    National Research Council Canada - National Science Library

    Goldstein, Rachel Y; Kaye, Ian David; Slover, James; Feldman, David

    2014-01-01

    .... These characteristic changes result in intraarticular pathology leading to hip arthritis. A variety of treatment options exist based on the degree of dysplasia and the amount of concomitant hip arthritis...

  12. Calculated electronic and magnetic structure of screw dislocations in alpha iron

    Energy Technology Data Exchange (ETDEWEB)

    Odbadrakh, Khorgolkhuu [ORNL; Rusanu, Aurelian [ORNL; Stocks, George Malcolm [ORNL; Samolyuk, German D [ORNL; Eisenbach, Markus [ORNL; Wang, Yang Nmn [ORNL; Nicholson, Don M [ORNL

    2011-01-01

    Local atomic magnetic moments in crystalline Fe are perturbed by the presence of dislocations. The effects are most pronounced near the dislocation core and decay slowly as the strain field of the dislocation decreases with distance. We have calculated local moments using the locally self-consistent multiple scattering (LSMS) method for a supercell containing a screw-dislocation quadrupole. Finite size effects are found to be significant indicating that dislocation cores affect the electronic structure and magnetic moments of neighboring dislocations. The influence of neighboring dislocations points to a need to study individual dislocations from first principles just as they appear amid surrounding atoms in large-scale classical force field simulations. An approach for the use of the LSMS to calculate local moments in subvolumes of large atomic configurations generated in the course of classical molecular dynamics simulation of dislocation dynamics is discussed. VC2011 American Institute of Physics. [doi:10.1063/1.3562217

  13. Exercise therapy may postpone total hip replacement surgery in patients with hip osteoarthritis

    DEFF Research Database (Denmark)

    Svege, Ida; Nordsletten, Lars; Fernandes, Linda

    2015-01-01

    Exercise treatment is recommended for all patients with hip osteoarthritis (OA), but its effect on the long-term need for total hip replacement (THR) is unknown.......Exercise treatment is recommended for all patients with hip osteoarthritis (OA), but its effect on the long-term need for total hip replacement (THR) is unknown....

  14. 21 CFR 888.3400 - Hip joint femoral (hemi-hip) metallic resurfacing prosthesis.

    Science.gov (United States)

    2010-04-01

    ... prosthesis. 888.3400 Section 888.3400 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND... femoral (hemi-hip) metallic resurfacing prosthesis. (a) Identification. A hip joint femoral (hemi-hip) metallic resurfacing prosthesis is a device intended to be implanted to replace a portion of the hip...

  15. 21 CFR 888.3370 - Hip joint (hemi-hip) acetabular metal cemented prosthesis.

    Science.gov (United States)

    2010-04-01

    ... prosthesis. 888.3370 Section 888.3370 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND... (hemi-hip) acetabular metal cemented prosthesis. (a) Identification. A hip joint (hemi-hip) acetabular metal cemented prosthesis is a device intended to be implanted to replace a portion of the hip...

  16. 21 CFR 888.3360 - Hip joint femoral (hemi-hip) metallic cemented or uncemented prosthesis.

    Science.gov (United States)

    2010-04-01

    ... uncemented prosthesis. 888.3360 Section 888.3360 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF... Hip joint femoral (hemi-hip) metallic cemented or uncemented prosthesis. (a) Identification. A hip joint femoral (hemi-hip) metallic cemented or uncemented prosthesis is a device intended to be...

  17. Infection in periprosthetic hip fractures.

    Science.gov (United States)

    Cabral, Rui

    2012-01-01

    Fracture around the acetabulum and femur in total hip arthroplasty is a possible complication, sometimes with difficult surgical solution, namely when a sepsis is present. Periprosthetic hip fractures were classified according to a modified Vancouver classification. We treated 112 patients (67 men and 45 women) with periprosthetic hip fractures: 105 femoral fractures (94%) and seven acetabular fractures (6%). Mean follow-up was 10.6 years. For Type A (seven cases - 7%), B1 (10 cases - 10%) or C (13 cases - 12%) fractures around well fixed femoral stems we only fixed the fractures. For Type B2 (17 cases - 16%), B3 (46 cases - 44%) and D (12 cases - 11%, with associated fractures, not contemplated in the Vancouver classification) we used an uncemented long femoral stem, fixation with metallic cables and cancellous bone allografts to fill the femoral bone loss. We observed a deep infection in three patients (2.7%), three early hip dislocations treated by closed reductions, two cases with asymptomatic trochanteric non-union and one femoral refracture. In the three infection cases we performed two-stage revision with cementless hip prosthesis, using an antibiotic-loaded cement hip spacer (three to eight months), a six weeks period of parenteral antibiotics and we performed articular aspiration before revision surgery. Until now, we did not observe any re-infection. It is very important to make an early diagnosis, isolate micro-organisms and ensure their antibiotic susceptibility. The surgery solution depends on the well fixed implants and periprosthetic osteolysis and articular instability.

  18. Screw angulation affects bone-screw stresses and bone graft load sharing in anterior cervical corpectomy fusion with a rigid screw-plate construct: a finite element model study.

    Science.gov (United States)

    Hussain, Mozammil; Natarajan, Raghu N; Fayyazi, Amir H; Braaksma, Brian R; Andersson, Gunnar B J; An, Howard S

    2009-12-01

    Anterior corpectomy and reconstruction with bone graft and a rigid screw-plate construct is an established procedure for treatment of cervical neural compression. Despite its reliability in relieving symptoms, there is a high rate of construct failure, especially in multilevel cases. There has been no study evaluating the biomechanical effects of screw angulation on construct stability; this study investigates the C4-C7 construct stability and load-sharing properties among varying screw angulations in a rigid plate-screw construct. A finite element model of a two-level cervical corpectomy with static anterior cervical plate. A three-dimensional finite element (FE) model of an intact C3-T1 segment was developed and validated. From this intact model, a fusion model (two-level [C5, C6] anterior corpectomy) was developed and validated. After corpectomy, allograft interbody fusion with a rigid anterior screw-plate construct was created from C4 to C7. Five additional FE models were developed from the fusion model corresponding to five different combinations of screw angulations within the vertebral bodies (C4, C7): (0 degrees, 0 degrees), (5 degrees, 5 degrees), (10 degrees, 10 degrees), (15 degrees, 15 degrees), and (15 degrees, 0 degrees). The fifth fusion model was termed as a hybrid fusion model. The stability of a two-level corpectomy reconstruction is not dependent on the position of the screws. Despite the locked screw-plate interface, some degree of load sharing is transmitted to the graft. The load seen by the graft and the shear stress at the bone-screw junction is dependent on the angle of the screws with respect to the end plate. Higher stresses are seen at more divergent angles, particularly at the lower level of the construct. This study suggests that screw divergence from the end plates not only increases load transmission to the graft but also predisposes the screws to higher shear forces after corpectomy reconstruction. In particular, the inferior screw

  19. Transient osteoporosis of the hip.

    Science.gov (United States)

    Mirza, Rabeea; Ishaq, Saliha; Amjad, Hira

    2012-02-01

    Transient Osteoporosis of Hip (TOH) is an uncommon disorder of idiopathic nature, particularly in the Asian population. It has been described to mostly occur in middle aged men and women in their third trimester of pregnancy. A distinctive hallmark of this condition is that it is self limiting and resolves in a few months. The patient presents to the physician with pain on movement and impaired mobility of the affected joint, developing without any history of trauma. MRI is the main diagnostic tool. We report herein a case of a forty five year old male, who developed transient osteoporosis of the hip, and was managed conservatively.

  20. [Tendinitis of the hip region].

    Science.gov (United States)

    Samson, M; Lequesne, M

    1991-06-21

    Tendinitis and bursitis are less common around the hip than around the shoulder. Nevertheless, they must be recognized to avoid unnecessary and costly diagnostic errors. Their various clinical forms are studied in detail. Tendino-bursitis of the gluteus medius muscle is the most frequent in its subacute form, but it is rare in its acute, pseudo-gouty form. Calcification of the reflected tendon of the rectus femoris muscle often closely resembles arthritis of the hip. Synovial cysts of the psoas bursa and rupture of the gluteus medius tendon are rare but must be known. Local injections of corticosteroids play an important part in the treatment of these diseases.

  1. Hip-Hop发烧友

    Institute of Scientific and Technical Information of China (English)

    文泉; 张鹏

    2005-01-01

    我出生在布朗克斯。我只有三十岁。我一直是争论的焦点。我一年可以赚数十亿美元,而且非常非常红。你知道我是谁吗?我是Hip-Hop。三十年前“hip hop”这个词儿还不存在,如今它已经成为一种几乎难以定义的包罗万象的生活方式。

  2. Computed tomography in abnormalities of the hip

    Energy Technology Data Exchange (ETDEWEB)

    Visser, J.D.; Jonkers, A.; Klasen, H.J. (Rijksuniversiteit Groningen (Netherlands). Academisch Ziekenhuis); Hillen, B. (Rijksuniversiteit Groningen (Netherlands). Lab. voor Anatomie en Embryologie)

    1982-06-26

    The value of computed tomography in the assessment of abnormalities of the hip is demonstrated with the aid of an anatomical preparation and in patients with, respectively, congenital dislocation of a hip, dislocation of the hip in spina bifida, an acetabular fracture and a Ewing tumour. The anteversion of the acetabulum and femur and the instability index of the hip joint can be measured by means of computed tomography.

  3. Ultrasonography of the hip and lower extremity.

    Science.gov (United States)

    Malanga, Gerard A; Dentico, Richard; Halperin, Jonathan S

    2010-08-01

    Musculoskeletal ultrasonographic evaluation of the proximal lower limb includes the evaluation of the soft tissue structures, including tendons, ligaments, or muscles, and the bony structures of this region, include the hip, pubic symphysis, and sacroiliac joints. The evaluation of the hip or proximal lower limb region can be performed in an efficient and systematic manner. Ultrasonography of the lateral hip, intra-articular hip, medial thigh, and posterior thigh are discussed in the article. Copyright 2010 Elsevier Inc. All rights reserved.

  4. On HIP-HOP%HIP-HOP运动论

    Institute of Scientific and Technical Information of China (English)

    王丽娜; 兰健

    2009-01-01

    运用文献资料等方法,从文化社会学的角度对传入我国的HIP-HOP运动的文化背景及其文化表现进行分析.认为:HIP-HOP运动主要包括:街舞、街头篮球、滑板等运动.HIP-HOP运动以其流行的社会文化要素和独特魅力吸引亿万青少年,使其狂热地投入到这股新兴的运动时尚潮流中,影响和改变着青少年的现代生活.HIP-HOP运动创造了一种非冲突性的、娱乐休闲的,以及有理想化价值的身体娱乐体系,有着独有的体育文化功能.

  5. Evaluation of Occipitocervical Arthrodesis Rates with Screw-based Fixation and Osteoinductive Fusion Adjuncts.

    Science.gov (United States)

    Stone, Jeremy G; Panczykowski, David M; Tempel, Zachary J; Tormenti, Matthew; Kanter, Adam S; Okonkwo, David O

    2015-09-01

    Occipitocervical (OC) instability may be associated with neurologic impairment and even death. There is a paucity of research on the rate of arthrodesis utilizing modern screw-based constructs coupled with adjuvant osteoinductive agents. We reviewed our experience with OC constructs and compared the fusion rate, functional outcome, and rate of adverse events between recombinant human bone morphogenetic protein (BMP)-2, autologous iliac crest bone graft (ICBG), a combination of BMP and ICBG, and local bone autograft alone. We performed a retrospective cohort analysis of all adult admissions for operative treatment of OC instability utilizing segmental screw-based constructs for OC arthrodesis between January 2003 and September 2012. Data concerning demographic characteristics, diagnostic and procedural details, radiographic pathology, and clinical course were abstracted from medical records. The primary end point was evidence of stable fixation and osseous union on either dynamic lateral radiographs or computed tomography (CT) imaging at most recent follow-up. Secondary end points included functional outcome as determined by Nurick scale and Neck disability index (NDI) at ≥ 1year postoperation, as well as perioperative morbidity and mortality at 30 days and 3 months. During the study period, 94 patients (mean age: 62 ± 18 years) underwent OC fixation with segmental screw-based constructs. The four fusion adjunct cohorts analyzed included local autograft alone (32%), ICBG (41%), BMP (14%), or a combination of ICBG and BMP (14%). Notably, demineralized bone matrix was also used in 61% of cases overall, but its use did not differ significantly among the four cohorts (p = 0.28). Median radiographic follow-up was 6 months postoperatively (range: 1.5-54 months). Clinical outcomes were assessed at a median postoperative follow-up of 45 months (range: 12-87 months). Overall, radiographic evidence of arthrodesis was present in 83% of patients assessed and was

  6. Introductory study to mathematics modelling of fluid flow in the screw compressors; Einfuehrungsstudie zur mathematischen Modellierung der Stroemungen in Schraubenkompressoren

    Energy Technology Data Exchange (ETDEWEB)

    Svigler, J.; Vimmr, J. [Westboehmische Univ. Pilsen (Czechoslovakia). Lehrstuhl fuer Mechanik

    2000-07-01

    A fast development of the screw machines leads to the investigation of the physical processes, which take place in the work space of the screw machine and in the gaps on its boundary. These processes have a great influence on the performance of the screw machine especially with regard to its efficiency, therefore its knowledge is very important. It is necessary to turn our attention to the fluid dynamics of the screw machines. This paper deals with the preliminary analysis of the fluid flow in the screw machines. In this paper numerical computation of the compressible inviscid fluid flow in the work space of the screw machines and through the sealing gaps which are situated between the stator and the head of the female rotor tooth, is presented. The mathematical model of two- and three-dimensional inviscid compressible flow is described by the conservative system of the Euler equations. This problem was solved by the cell-centred finite volume method on a structured quadrilateral mesh. (orig.) [German] Die schnelle Entwicklung der Schraubenmaschinen fuehrt zur Notwendigkeit einer Untersuchung der physikalischen Vorgaenge, die im Arbeitsraum und in den arbeitsraumbegrenzenden Spalten der Schraubenmaschine ablaufen. Diese Vorgaenge beeinflussen nachhaltig das Betriebsverhalten sowie die Energiewandlungsguete, womit deren Kenntnis und der Information ueber die Details eine ausserordentliche Bedeutung zukommt. Einen Ausgangspunkt fuer die Analyse stellen die Kenntnisse im Bereich der kompressiblen Fluide dar. Der Zustand kann vor allem durch das Geschwindigkeits-, Druck-, und Temperaturfeld beurteilt werden. Der Beitrag beschaeftigt sich mit der Problematik der Stroemungsuntersuchungen des Gases im Arbeitsraum der Schaubenmaschine und im Gehaeusespalt. Die Aufgabe wird dreidimensional behandelt und auf eine Art und Weise formuliert, dass sie die Voraussetzung fuer die Erstellung eines raeumlichen Modells und der damit gekoppelten mathematischen Loesung schafft. Die

  7. Association of hip pain with radiographic evidence of hip osteoarthritis: diagnostic test study

    OpenAIRE

    Kim, Chan; Nevitt, Michael C.; Niu, Jingbo; Clancy, Mary M; Nancy E Lane; Link, Thomas M.; Vlad, Steven; Tolstykh, Irina; Jungmann, Pia M.; Felson, David T.; Guermazi, Ali

    2015-01-01

    Study question Is there concordance between hip pain and radiographic hip osteoarthritis? Methods In this diagnostic test study, pelvic radiographs were assessed for hip osteoarthritis in two cohorts: the Framingham Osteoarthritis Study (community of Framingham, Massachusetts) and the Osteoarthritis Initiative (a multicenter longitudinal cohort study of osteoarthritis in the United States). Using visual representation of the hip joint, participants reported whether they had hip pain on most d...

  8. Federalismo, dinâmica eleitoral e políticas públicas no Brasil: uma tipologia e algumas hipóteses Federalism, electoral dynamics and public policies in Brazil: a typology and some hypotheses

    Directory of Open Access Journals (Sweden)

    André Borges

    2010-08-01

    Full Text Available O presente trabalho propõe um modelo tipológico capaz de fundamentar o entendimento da conexão entre políticas públicas e dinâmica eleitoral em uma democracia federal onde o poder de formular e implementar políticas públicas é relativamente descentralizado. De modo mais geral, esta tipologia de políticas públicas pretende avançar além das dicotomias tradicionais da ciência política - clientelismo vs. universalismo / partidos catch-all vs. partidos programáticos - oferecendo uma nova perspectiva analítica, de corte não dualista. A tipologia classifica as políticas públicas a partir de duas dimensões: os critérios de alocação de recursos (políticopartidários ou universalistas e a natureza dos bens e serviços produzidos (privados ou públicos. A partir do cruzamento das duas dimensões, o trabalho define quatro tipos de estratégias de implementação de políticas públicas: clientelismo, política distributiva, focalização e universalismo. Também são definidas algumas hipóteses capazes de explicar as escolhas de política pública realizadas pelos governos subnacionais. O trabalho leva em conta três ordens de fatores explicativos: competição política horizontal (entre partidos políticos, competição vertical (entre esferas de governo e contexto socioeconômico e demográfico.This paper proposes a typological model to provide further understanding of the connection between public policies and electoral dynamics in a federal democracy in which the power to formulate and implement public policies is relatively decentralized. More generally, this typology of public policies is intended to move beyond the traditional dichotomies of political science - clientelism vs. universalism / catch-all parties vs. programmatic parties - offering a new analytical perspective, with a non-dualistic approach. The typology classifies public policies according to two dimensions: the criteria for allocation of resources (partisan

  9. Ensaios estáticos de flexão e rigidez em placas do tipo sistema dinâmico do quadril (DHS Static load test on dynamic hip system (DHS plates

    Directory of Open Access Journals (Sweden)

    Anderson Freitas

    2009-01-01

    Full Text Available OBJETIVO: Avaliar isolada e comparativamente placas do tipo sistema dinâmico do quadril (DHS de dois fabricantes nacionais, analisar estatisticamente seus resultados e demonstrar a falta de determinantes para sua fabricação. MÉTODOS: Foram realizados ensaios estáticos de flexão em cinco placas DHS do fabricante I (grupo I e em igual quantidade do mesmo modelo do fabricante II (grupo II, sendo todas fabricadas em aço inoxidável austenítico ASTM F 138, com quatro furos e angulação de 135º. Utilizou-se máquina servohidráulica MTS, modelo Test Star II®, com capacidade de carga de 10 toneladas e controle de deslocamento. Foram obtidos dados da carga aplicada (P em função do deslocamento vertical do pistão (L, cuja velocidade foi 5 mm/min. Os ensaios foram interrompidos após atingir a deflexão vertical máxima especificada pelas normas dos ensaios. RESULTADOS: Grupo I: resistência de flexão, 161,4 ± 17,2 kgf rigidez, 64,5 ± 1,8 kgf/mm, ductilidade, > 25,4 mm. Grupo II: resistência de flexão, 124,7 ± 4,4, rigidez 59,6 ± 2,3, ductilidade > 25,4 mm. Para análise estatística foi adotado o teste de Mann-Whitney e a determinação de significância foi de 5% (pOBJECTIVE: To evaluate, both individually and comparatively, dynamic hip system-type plates marketed by two local manufacturers, to statistically analyze its results and show the lack of parameters for its manufacturing. METHODS: Static tests of flexion were carried out in five DHS plates of the manufacturer I (I group I and in equal quantity of the same model of the manufacturer II (I group II, being all made in stainless austenitic ASTM F 138 steel, with four holes and a 135º angle. A servo-hydraulic MTS machine, Test Star II model, was used with a load capacity of 10 tons and dislocation control. The data were obtained from the applied load (P as a function of the vertical dislocation of the piston (L, whose speed was 5mm/min. The tests were shutdown after reaching

  10. Retroperitoneal hematoma with bone resorption around the acetabular component after total hip arthroplasty: a case report and review of the literature

    Directory of Open Access Journals (Sweden)

    Uchida Kenzo

    2012-09-01

    Full Text Available Abstract Introduction Vascular complications related to cup-fixating screws penetrating the medial acetabular wall during total hip arthroplasty are not uncommon but rarely are associated with serious adverse events in the late post-operative period. Case presentation We present the case of a 77-year-old Japanese woman who developed progressive extensive bone resorption and large hematoma in the acetabulum 13 years after total hip arthroplasty. On admission to our hospital, she was on oral warfarin (1.5mg/day for atrial fibrillation. About 5 months after the initiation of anticoagulant therapy, she suffered a major fall followed by massive subcutaneous and pelvic girdle bleeding, predominantly on the medial side of the right thigh, but a fracture or damage of total hip arthroplasty was not evident on an emergency orthopedic evaluation. One year after the accident, a routine follow-up examination showed an asymptomatic osteolytic lesion in the acetabulum on the right pelvis, and 2 years later our patient noticed progressive pain in her right hip during walking. A large osteolytic lesion was noted in the right acetabulum on a plain radiograph. On high-resolution computed tomography and magnetic resonance imaging, a huge granulomatous lesion in the acetabulum was suggestive of chronic hematoma in intrapelvic and extrapelvic gluteal regions. A closer computed tomography examination showed that one of the screws used for fixation of the acetabular component in the total hip arthroplasty had penetrated the acetabular bone and had reached the pelvic cavity. Surgery was performed in a single session by means of two approaches: anterior midline transperitoneal address to resect the low-density mass lesion followed by posterolateral acetabular implant re-settlement. Conclusions Though rare, total hip arthroplasty-related late vascular complications could be serious and potentially affect the limb and quality of life.

  11. Total Hip Arthroplasty in Failed Hip Fractures: A Case Series

    Directory of Open Access Journals (Sweden)

    Syed Shahid Noor

    2015-01-01

    Full Text Available Osteoporosis is epidemic in Asian countries. It is a major cause of fractures that orthopaedic surgeons deal in Pakistan, though proper epidemiological data is not available. Habiba U et al found that 75.3% of post menopausal women of Pakistan were predisposed to Osteoporosis; whereas Baig L has described an average T - score of -1.833±0.65 on bone mineral density calculation of post menopausal females of Pakistan. Osteoporotic hip fractures constitute a major cause of elderly mortality worldwide and recent figures supporting the idea that these patients have survival rates comparable to breast and thyroid cancer patients. Pakistan is a developing country with large burden of hip fractures. Patients living in remote areas are the ones which suffer more because of inadequate awareness, fear of surgical treatment and lack of availability of standard treatment. These patients are dealt by surgeons of various expertise and levels of experience. Lack of facilities in hospitals is well known and usage of sub-standard implant is a major cause of failure. Therefore these patients either because of their bone fragility or mal-treatment suffer frequently from failure of hip fracture surgeries. Being in a tertiary care centre we come across these types of cases very frequently. Six to eight such cases present to outpatient department of Liaquat National Hospital every month being referred from every part of the country. These patients may have been operated once, twice or even multiple times. Special attention is required to acquire an informative history from these cases and perform a comprehensive examination. Moreover previous records and radiographs provide invaluable information regarding cause of failure and deciding course of further treatment. We herein discuss few of the cases of failure of hip fractures which were treated by hip arthroplasty.

  12. Ipsilateral fracture dislocations of the hip and knee joints with contralateral open fracture of the leg: a rare case and its management principles

    Institute of Scientific and Technical Information of China (English)

    Ramesh Kumar Sen; Sujit Kumar Tripathy; Vibhu Krishnan; Tarun Goyal; Vanyambadi Jagadeesh

    2011-01-01

    This paper discussed the injury mechanism and management of a patient who had concomitant ipsilateral hip and knee dislocations and contralateral open leg fracture.A 32-year-old man presented with ipsilateral fracturedislocations of the left hip (Pipkin's type Ⅳ) and knee (Moore Ⅱ)joints and contralateral open fracture of the leg bones after a car accident. After emergency resuscitative measures, the hip joint was reduced and Pipkin's fracture was fixed using Ganz approach with lag screws; knee joint was reduced closely and tibial plateau fracture was stabilized with lateral buttress plate and a transarticular spanning fixator. The open fracture on the other leg was debrided and fixed with an external fixator. There was no instability in both joints after fixation when he was examined under anesthesia. The fractures united after 3 months and the patient had no residual instability of hip and knee. There was no clinical or radiological evidence of osteonecrosis in the hip joint after 6 months. At one-year follow-up, he had satisfactory functional outcome with almost normal range of motion at both joints.Ipsilateral hip and knee dislocations are rare injuries and more caution is needed for early diagnosis. A timely appropriate intervention can provide good functional outcome to the patient in this situation.

  13. Preoperative gait adaptations persist one year after surgery in clinically well-functioning total hip replacement patients.

    Science.gov (United States)

    Foucher, Kharma C; Hurwitz, Debra E; Wimmer, Markus A

    2007-01-01

    The purpose of this study was to evaluate whether preoperative gait adaptations persist one year after THR in the same set of subjects. The hypothesis tested was that hip dynamic range of motion and peak external moments during walking return to normal after THR. Hip kinematics and kinetics were measured for 28 subjects before and one year after THR and compared to those of 25 subjects with radiographically normal hips. All THR subjects improved clinically after surgery with Harris hip scores improving from 33-85 (average 53) to 61-100 (average 95) (sign test pPreoperatively dynamic hip range of motion (ROM), and all peak external moments were reduced compared to normal (Mann-Whitney ppreoperative and postoperative values of the ROM, and peak flexion, abduction and external rotation moments were all significantly correlated (Spearman prehabilitation before and after surgery.

  14. Planetary Suit Hip Bearing Model for Predicting Design vs. Performance

    Science.gov (United States)

    Cowley, Matthew S.; Margerum, Sarah; Harvil, Lauren; Rajulu, Sudhakar

    2011-01-01

    , the suited performance trends were comparable between the model and the suited subjects. With the three off-nominal bearing configurations compared to the nominal bearing configurations, human subjects showed decreases in hip flexion of 64%, 6%, and 13% and in hip abduction of 59%, 2%, and 20%. Likewise the solid model showed decreases in hip flexion of 58%, 1%, and 25% and in hip abduction of 56%, 0%, and 30%, under the same condition changes from the nominal configuration. Differences seen between the model predictions and the human subject performance data could be attributed to the model lacking dynamic elements and performing kinematic analysis only, the level of fit of the subjects with the suit, the levels of the subject s suit experience.

  15. 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.

  16. 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...

  17. 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...

  18. 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.

  19. 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

  20. 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