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Sample records for head metal-on-metal cementless

  1. Large head metal-on-metal cementless total hip arthroplasty versus 28mm metal-on-polyethylene cementless total hip arthroplasty: design of a randomized controlled trial

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    van Raaij Jos JAM

    2008-10-01

    Full Text Available Abstract Background Osteoarthritis of the hip is successfully treated by total hip arthroplasty with metal-on-polyethylene articulation. Polyethylene wear debris can however lead to osteolysis, aseptic loosening and failure of the implant. Large head metal-on-metal total hip arthroplasty may overcome polyethylene wear induced prosthetic failure, but can increase systemic cobalt and chromium ion concentrations. The objective of this study is to compare two cementless total hip arthroplasties: a conventional 28 mm metal-on-polyethylene articulation and a large head metal-on-metal articulation. We hypothesize that the latter arthroplasties show less bone density loss and higher serum metal ion concentrations. We expect equal functional scores, greater range of motion, fewer dislocations, fewer periprosthetic radiolucencies and increased prosthetic survival with the metal-on-metal articulation. Methods A randomized controlled trial will be conducted. Patients to be included suffer from non-inflammatory degenerative joint disease of the hip, are aged between 18 and 80 and are admitted for primary cementless unilateral total hip arthroplasty. Patients in the metal-on-metal group will receive a cementless titanium alloy acetabular component with a cobalt-chromium liner and a cobalt-chromium femoral head varying from 38 to 60 mm. Patients in the metal-on-polyethylene group will receive a cementless titanium alloy acetabular component with a polyethylene liner and a 28 mm cobalt-chromium femoral head. We will assess acetabular bone mineral density by dual energy x-ray absorptiometry (DEXA, serum ion concentrations of cobalt, chromium and titanium, self reported functional status (Oxford hip score, physician reported functional status and range of motion (Harris hip score, number of dislocations and prosthetic survival. Measurements will take place preoperatively, perioperatively, and postoperatively (6 weeks, 1 year, 5 years and 10 years. Discussion

  2. No clinical difference between large metal-on-metal total hip arthroplasty and 28-mm-head total hip arthroplasty?

    NARCIS (Netherlands)

    Zijlstra, Wierd P; van den Akker-Scheek, Inge; Zee, Mark J M; van Raay, Jos J A M

    2011-01-01

    PURPOSE: We aimed to test the claim of greater range of motion (ROM) with large femoral head metal-on-metal total hip arthroplasty. METHODS: We compared 28-mm metal-on-polyethylene (MP) total hip arthroplasty with large femoral head metal-on-metal (MM) total hip arthroplasty in a randomised clinical

  3. Sequelae of large-head metal-on-metal hip arthroplasties

    OpenAIRE

    van Lingen, Christiaan P.; Zagra, Luigi M.; Ettema, Harmen B.; Verheyen, Cees C.

    2016-01-01

    Large-head metal-on-metal (MoM) bearings were re-popularised in the late 1990s with the introduction of modern hip resurfacing (HR), followed closely by large metal head total hip arthroplasty (THA). A worldwide increase in the use of MoM hip arthroplasty subsequently saw a sharp decline, due to serious complications. MoM was rapidly adopted in the early 2000s until medical device alerts were issued by government regulatory agencies and national and international organisations, leading to pos...

  4. Sequelae of large-head metal-on-metal hip arthroplasties

    Science.gov (United States)

    van Lingen, Christiaan P.; Zagra, Luigi M.; Ettema, Harmen B.; Verheyen, Cees C.

    2016-01-01

    Large-head metal-on-metal (MoM) bearings were re-popularised in the late 1990s with the introduction of modern hip resurfacing (HR), followed closely by large metal head total hip arthroplasty (THA). A worldwide increase in the use of MoM hip arthroplasty subsequently saw a sharp decline, due to serious complications. MoM was rapidly adopted in the early 2000s until medical device alerts were issued by government regulatory agencies and national and international organisations, leading to post-marketing surveillance and discontinuation of these implants. Guidelines for MoM hip implant follow-up differ considerably between regulatory authorities worldwide; this can in part be attributed to missing or conflicting evidence. The authors consider that the use of large-head MoM THA should be discontinued. MoM HR should be approached with caution and, when considered, should be used only in patients who meet all of the recommended selection criteria, which limits its indications considerably. The phased introduction of new prostheses should be mandatory in future. Close monitoring of outcomes and long-term follow-up is also necessary for the introduction of new prostheses. Cite this article: van Lingen CP, Zagra LM, Ettema HB, Verheyen CC. Sequelae of large-head metal-on-metal hip arthroplasties: current status and future prospects. EFORT Open Rev 2016;1:345-353. DOI: 10.1302/2058-5241.1.160014. PMID:28461912

  5. Tribology and wear of metal-on-metal hip prostheses: influence of cup angle and head position.

    Science.gov (United States)

    Williams, Sophie; Leslie, Ian; Isaac, Graham; Jin, Zhongmin; Ingham, Eileen; Fisher, John

    2008-08-01

    Clinical studies have indicated that the angular position of the acetabular cup may influence wear in metal-on-metal total hip bearings. A high cup angle in comparison to the anatomical position may lead to the head being constrained by the superior lateral surface and rim of the cup, thus potentially changing the location of the contact zone between the head and the cup. The aim of this study was to test the hypothesis that both a steep cup angle and a lateralized position of the head can increase head contact on the superior rim of the cup, with the consequence of increased wear. Hip-joint simulator studies of metal-on-metal bearings were undertaken with cup angles of 45 degrees and 55 degrees . The femoral head was either aligned to the center of the cup or placed in a position of microlateralization. Wear was measured gravimetrically over 5 million cycles. A steep cup angle of 55 degrees showed significantly higher long-term steady-state wear than a standard cup angle of 45 degrees (p < 0.01). The difference was fivefold. Microlateralization of the head resulted in a fivefold increase in steady-state wear compared with a centralized head. The combination of a steep cup angle and a microlateralized head increased the steady-state wear rate by tenfold compared with a standard cup angle with a centralized head. These studies support the hypothesis that both an increased cup angle and a lateral head position increase wear in metal-on-metal hip prostheses.

  6. Mechanically assisted crevice corrosion of the head-neck taper in a large head metal-on-metal total hip arthroplasty

    OpenAIRE

    Moskal, Joseph; Stover, Matthew

    2015-01-01

    Taper corrosion of the head-neck junction is a potentially significant and devastating problem facing orthopedic surgeons. We present a case of a 53 year old male who presented for routine follow up for a left, large head, metal on metal total hip arthroplasty five years out. The patient was asymptomatic at the visit. X-rays at the time demonstrated a large amount of medial calcar osteolysis. Serum ion levels revealed a mildly increased cobalt and normal chromium level and hip aspiration reve...

  7. Quantitative analysis of orthopedic metal artefact reduction in 64-slice computed tomography scans in large head metal-on-metal total hip replacement, a phantom study

    NARCIS (Netherlands)

    Boomsma, Martijn F.; Warringa, Niek; Edens, Mireille A.; Mueller, Dirk; Ettema, Harmen B.; Verheyen, Cees C. P. M.; Maas, Mario

    2016-01-01

    Purpose: Quantification of the effect of O-MAR on decreasing metal artefacts caused by large head metal on metal total hip arthroplasty (MoM THA) in a dedicated phantom setup of the hip. Background: Pathological reactions of the hip capsule on Computed tomography (CT) can be difficult to diagnose

  8. What Is the Long-term Survival for Primary THA With Small-head Metal-on-metal Bearings?

    Science.gov (United States)

    de Steiger, Richard; Peng, Andrea; Lewis, Peter; Graves, Stephen

    2018-02-08

    Large-head metal-on-metal (MoM) bearing hip replacements have been shown to have a much higher rate of revision than other bearing surfaces. However, small-head (≤ 32 mm) MoM bearing surfaces have been in use for many years with several reports of satisfactory mid- to long-term survivorship. It is unclear whether the long-term survival of small-head MoM devices will continue to be satisfactory or whether the same concerns seen with the large-head MoM devices will ultimately become more prevalent. We analyzed a large national registry to ask: (1) What is the 15-year Kaplan-Meier survivorship of primary conventional THA using small-head (≤ 32 mm) MoM bearing surfaces compared with large-head MoM bearing surfaces in primary THA? (2) Is there an increased rate of revision for adverse reaction to metal debris (ARMD) in this group of patients over time? The Australian Orthopaedic Association National Joint Replacement Registry longitudinally maintains data on all primary and revision joint arthroplasties with nearly 100% capture. We analyzed all conventional primary THAs performed from Registry inception in September 1999 until December 31, 2015, in patients with a diagnosis of osteoarthritis and using MoM bearing surfaces ≤ 32 mm in diameter, defined as small-head MoM. The study group included 4838 primary THA with ≤ 32-mm MoM bearing surfaces. There were 2506 (51.8%) male patients and the median age of patients undergoing THA with a small-head MoM bearing surface was 64 years (range, 20-92 years of age). The outcome measure was the cumulative percent revision defined as the time to first revision using Kaplan-Meier estimates of survivorship at 15 years; reasons for revision and type of revision were also examined. We specifically investigated whether there was an increased risk of revision for ARMD in this MoM group compared with all other bearing surfaces. We compared these results with large-head MoM THAs (femoral head size > 32 mm). The cumulative percent

  9. Modular to Monoblock: Difficulties of Detaching the M(2)a-Magnum(TM) Head Are Common in Metal-on-metal Revisions.

    Science.gov (United States)

    Mäntymäki, Heikki; Mäkelä, Keijo T; Vahlberg, Tero; Hirviniemi, Joni; Niinimäki, Tuukka

    2016-09-01

    Modern hip implants typically feature modular heads, which allow for easy exchange and removal from the femoral stem at the time of revision. However, owing to fretting, corrosion, or cold welding, the modular head may be difficult or impossible to separate from the underlying trunnion, especially if the implant has titanium interfaces between the head and the stem. We have repeatedly encountered difficulty removing the titanium sleeve adapter in the M(2)a-Magnum(TM) implant. Although the manufacturer warns about this complication and cases with these difficulties have been reported to the United States FDA, we believed this topic is important to study, because the frequency of difficulties in head removal is unknown and the complications related to this event have not been characterized. We asked: (1) Do revisions of M(2)a-Magnum(TM) implants differ from those of M(2)a-38(TM) implants in terms of ease of removal of the femoral head? (2) In cases where difficulty with M(2)a-Magnum(TM) head removal occurred, was the operative time, bleeding, risk of periprosthetic fracture, or joint infection increased compared with cases where the M(2)a-Magnum(TM) head was removed without difficulties? Between 2004 and 2014, we revised 296 THAs with metal-on-metal implants that involved M(2)a-Magnum(TM) (123) or M(2)a-38(TM) heads (88); of those, 84 were planned to include a femoral stem revision and insufficient data were available for three operations, so they were excluded from this analysis, leaving 124 THAs in the current retrospective study (70 THAs with M(2)a-Magnum(TM) and 54 THAs with M(2)a-38(TM) heads).The method of modular head removal, any difficulties removing the femoral head from the trunnion, operation time, and complications were recorded based on chart review. All the observed problems of detaching the head or taper adapter were among M(2)a-Magnum(TM) heads; there were no problems detaching the head in revisions of the M(2)a-38(TM) implant. In 29% (20 of 70) of

  10. Influence of head size on the development of metallic wear and on the characteristics of carbon layers in metal-on-metal hip joints.

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    Braunstein, Volker; Sprecher, Christoph M; Wimmer, Markus A; Milz, Stefan; Taeger, Georg

    2009-06-01

    Particles originating from the articulating surfaces of hip endoprostheses often induce an inflammatory response, which can be related to implant failure. We therefore analyzed the metal content in capsular tissue from 44 McKee-Farrar metal-on-metal hip prostheses (with 3 different head sizes) and we also analyzed the morphological structure of layers located on articulating surfaces. Atomic absorption spectrometry (AAS) was used to analyze the metal content in capsular tissue. Visually detectable carbon layers located on the articulating surfaces were evaluated using scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), and X-ray photoelectron spectroscopy (XPS). Metallic debris was detected in all capsular tissue samples but no statistically significant differences in metal content were found in relation to implant head size. The morphological characteristics of the different layer zones allowed an exact analysis of contact and non-contact areas. Furthermore, surface layers appear to have a protective function because they can prevent sharp-edged particles from damaging the prostheses surface. The implant head size does not appear to influence the amount of metallic debris. The layers obviously act like a lubricating agent because the protection function does not occur in regions without layers where the metal surface often shows numerous scratches. As layers are not generated immediately after the implantation of hip prostheses, these findings may at least partially explain the high amount of wear early after implantation.

  11. Block-step asymmetry 5 years after large-head metal-on-metal total hip arthroplasty is related to lower muscle mass and leg power on the implant side.

    Science.gov (United States)

    Hjorth, M H; Stilling, M; Lorenzen, N D; Jakobsen, S S; Soballe, K; Mechlenburg, I

    2014-06-01

    Metal-on-metal articulations mimic the human hip anatomy, presumably lower dislocation rates and increase the range-of-motion. This study aims to measure the muscle mass and power of both legs in patients with unilateral metal-on-metal total hip arthroplasty, and to investigate their effect on block-step test, spatio-temporal gait parameters and self-reported function. Twenty-eight patients (7 women), mean age 50 (28-68) years, participated in a 5-7 year follow-up. Patients had received one type unilateral large-head metal-on-metal total hip articulation, all of which were well-functioning at follow-up. Mean muscle mass was measured by the total-body Dual energy X-ray Absorption scans, and muscle power was measured in a leg extensor power rig. Block-step test and spatio-temporal gait parameters were measured with an inertial measurement unit. Self-reported function was assessed by the Hip Disability and Osteoarthritis Outcome Score. We found a significant difference between the mean muscle mass of the implant-side leg and the non-implant-side leg in hip, thigh and calf areas (Pmuscle power (P=0.025). Correlations between mean muscle mass and mean muscle power were significant for both the implant-side leg (r=0.45, P=0.018) and the non-implant-side leg (r=0.51, P=0.007). The difference in mean muscle power between legs correlated with block-step test asymmetry during ascending (r=0.40, P=0.047) and descending (r=0.53, P=0.006). Correlations between self-reported function and power of the implant-side leg were not significant. Young patients have not fully regained muscle mass, muscle power and function 5-7 years after metal-on-metal total hip arthroplasty. Copyright © 2014. Published by Elsevier Ltd.

  12. Metal-on-metal hip joint tribology.

    Science.gov (United States)

    Dowson, D; Jin, Z M

    2006-02-01

    The basic tribological features of metal-on-metal total hip replacements have been reviewed to facilitate an understanding of the engineering science underpinning the renaissance of these hard-on-hard joints. Metal-on-polymer hip replacements operate in the boundary lubrication regime, thus leading to the design guidance to reduce the femoral head diameter as much as is feasible to minimize frictional torque and volumetric wear. This explains why the gold-standard implant of this form from the past half-century had a diameter of only 22.225 mm (7/8 in). Metal-on-metal implants can operate in the mild mixed lubrication regime in which much of the applied load is supported by elastohydrodynamic films. Correct tribological design leads to remarkably low steady state wear rates. Promotion of the most effective elastohydrodynamic films calls for the largest possible head diameters and the smallest clearances that can reasonably be adopted, consistent with fine surface finishes, good sphericity and minimal structural elastic deformation of the cup on its foundations. This guidance, which is opposite in form to that developed for metal-on-polymer joints, is equally valid for solid (monolithic) metallic heads on metallic femoral stems and surface replacement femoral shells. Laboratory measurements of friction and wear in metal-on-metal joints have confirmed their potential to achieve a very mild form of mixed lubrication. The key lies in the generation of effective elastohydrodynamic lubricating films of adequate thickness compared with the composite roughness of the head and cup. The calculation of the film thickness is by no means easy, but the full procedure is outlined and the use of an empirical formula that displays good agreement with calculations based upon the full numerical solutions is explained. The representation of the lambda ratio, lambda, embracing both film thickness and composite roughness, is described.

  13. Uneven damage on head and liner contact surfaces of a retrieved Co–Cr-based metal-on-metal hip joint bearing: An important reason for the high failure rate

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    Koizumi, Yuichiro, E-mail: koizumi@imr.tohoku.ac.jp [Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, Miyagi 980-8577 (Japan); Chen, Yan; Li, Yunping; Yamanaka, Kenta; Chiba, Akihiko [Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, Miyagi 980-8577 (Japan); Tanaka, Shun-Ichiro [Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Katahira 2-1-1, Aoba-ku, Sendai 980-8577 (Japan); Hagiwara, Yoshihiro [Tohoku University School of Medicine, 2-1 Seiryo-machi, Aoba-ku, Sendai, Miyagi 980-8575 (Japan)

    2016-05-01

    Detailed metallurgical investigations have been performed on a used Co–Cr-based metal-on-metal (MoM) hip joint bearing containing a type of liner that is commonly used in such joints. The damage on the metal-liner sliding surface was considerably more severe than that on the metal head counterpart, in terms of wear-scar density and width and microcrack frequency. Cross-sectional transmission electron microscopy revealed that a thick (> 3 μm) nanocrystalline layer formed on the sliding surface of the head, whereas the liner had coarse carbides embedded in it and nanocrystals were formed in a very limited region no deeper than 1 μm. Comparative investigation of an unused head and a liner of identical type showed that although the chemical compositions of the liner and head were nearly identical, their microstructures were significantly different. Specifically, the grain size in the liner was larger than that in the head on average, and the grain boundaries of the liner were decorated with coarse carbides. Moreover, X-ray diffraction analysis revealed a large tensile residual stress only in the liner. These differences are possibly responsible for the wear damage on the liner being more serious than that on the head. - Highlights: • Microstructures in a used metal-on-metal (MoM) hip joint have been investigated in detail. • The damage on the liner sliding surface was considerably more severe than that on the head. • Relatively coarse microstructures are probably responsible for the severe damage on the liner.

  14. The effect of using components from different manufacturers on the rate of wear and corrosion of the head-stem taper junction of metal-on-metal hip arthroplasties.

    Science.gov (United States)

    Whittaker, R K; Hothi, H S; Meswania, J M; Berber, R; Blunn, G W; Skinner, J A; Hart, A J

    2016-07-01

    Surgeons have commonly used modular femoral heads and stems from different manufacturers, although this is not recommended by orthopaedic companies due to the different manufacturing processes. We compared the rate of corrosion and rate of wear at the trunnion/head taper junction in two groups of retrieved hips; those with mixed manufacturers (MM) and those from the same manufacturer (SM). We identified 151 retrieved hips with large-diameter cobalt-chromium heads; 51 of two designs that had been paired with stems from different manufacturers (MM) and 100 of seven designs paired with stems from the same manufacturer (SM). We determined the severity of corrosion with the Goldberg corrosion score and the volume of material loss at the head/stem junction. We used multivariable statistical analysis to determine if there was a significant difference between the two groups. We found no significant difference in the corrosion scores of the two groups. The median rate of material loss at the head/stem junction for the MM and SM groups were 0.39 mm(3)/year (0.00 to 4.73) and 0.46 mm(3)/year (0.00 to 6.71) respectively; this difference was not significant after controlling for confounding factors (p = 0.06). The use of stems with heads of another manufacturer does not appear to affect the amount of metal lost from the surfaces between these two components at total hip arthroplasty. Other surgical, implant and patient factors should be considered when determining the mechanisms of failure of large diameter metal-on-metal hip arthroplasties. Cite this article: Bone Joint J 2016;98-B:917-24. ©2016 The British Editorial Society of Bone & Joint Surgery.

  15. Evaluation of a metal-on-metal total hip arthroplasty

    OpenAIRE

    Dahlstrand, Henrik

    2017-01-01

    Background After the introduction of the Metasul system by Weber in 1988, total hip arthroplasty (THA) with metal-on-metal (MoM) bearings became increasingly popular in the 1990s. MoM bearings aimed to reduce the problem of aseptic loosening associated with polyethylene wear particles from conventional polyethylene cups. The following introduction of hip resurfacing added positive factors as bone sparing and large caliber heads, reducing the risk of dislocations. After alm...

  16. No association between pseudotumors, high serum metal-ion levels and metal hypersensitivity in large-head metal-on-metal total hip arthroplasty at 5-7-year follow-up

    DEFF Research Database (Denmark)

    Hjorth, Mette Holm; Stilling, Maiken; Soballe, Kjeld

    2016-01-01

    OBJECTIVE: The relationship between metal wear debris, pseudotumor formation and metal hypersensitivity is complex and not completely understood. The purpose of this study was to assess the prevalence of pseudotumor formation in a consecutive series of metal-on-metal (MoM) total hip arthroplasty ...

  17. Self-reported neurological clinical manifestations of metal toxicity in metal-on-metal hip arthroplasty

    NARCIS (Netherlands)

    van Lingen, Christiaan P.; Ettema, Harmen B.; Van Der Straeten, Catherine; Kollen, Bouwdewijn J.; Verheyen, Cees C. P. M.

    2014-01-01

    Adverse reactions to metal particle debris have been increasingly reported as a complication following large head metal-on-metal (MoM) hip arthroplasty. Elevated metal ion levels are a cause for concern. The aim of this study is to evaluate whether exposure to cobalt is associated with patient

  18. Metal-on-metal bearings a clinical practicum

    CERN Document Server

    Jones, Lynne C; Greenwald, A Seth

    2014-01-01

    This book addresses the background and significance of factors potentially influencing clinical and biological outcomes of metal-on-metal hip implants. Includes discussion of reported complications including pseudotumors and other lymphocytic-based responses.

  19. Metal-on-metal bearings total hip arthroplasty: the cobalt and chromium ions release concern.

    Science.gov (United States)

    Delaunay, C; Petit, I; Learmonth, I D; Oger, P; Vendittoli, P A

    2010-12-01

    With certain concerns recently reported on metal-on-metal bearing couples in total hip arthroplasty, this study's objective is to review the current knowledge concerning release of metal ions and its potential consequences. Each metal-on-metal implant presents different tribological properties. The analytical techniques for metals are accurate and the Co ion rates seem acceptable up to 2 μg/L. A delayed type IV hypersensitivity reaction (atypical lymphocytic vasculitis-associated lesion [ALVAL]) may be the source of arthroplasty failure. Idiosyncratic, it remains unpredictable even using cutaneous tests and apparently is rare (0.3%). Today, there are no scientific or epidemiologic data supporting a risk of carcinogenesis or teratogenesis related to the use of a metal-on-metal bearings couple. Solid pseudotumors nearly exclusively are observed with resurfacing procedures, carrying a high annual revision rate in women under 40 years of age, occurring particularly in cases of acetabular malposition and with use of cast molded Cr-Co alloys. Osteolysis manifests through complete and progressive radiolucent lines or through cavitary lesions stemming from ALVAL-type alterations or impingement problems or implant incompatibility. The formation of wear debris exceeding the biological tolerance is possible with implant malposition, subluxation, and jamming of the femoral head in cases of cup deformity. Moreover, each implant presents different metal ion production; assessment of their performance and safety is required before their clinical use. With the knowledge available today, metal-on-metal bearing couples are contraindicated in cases of metal allergies or end stage renal dysfunction and small size resurfacing should cautiously be used. Copyright © 2010. Published by Elsevier Masson SAS.

  20. Nano-analyses of wear particles from metal-on-metal and non-metal-on-metal dual modular neck hip arthroplasty.

    Science.gov (United States)

    Xia, Zhidao; Ricciardi, Benjamin F; Liu, Zhao; von Ruhland, Christopher; Ward, Mike; Lord, Alex; Hughes, Louise; Goldring, Steven R; Purdue, Edward; Murray, David; Perino, Giorgio

    2017-04-01

    Increased failure rates due to metallic wear particle-associated adverse local tissue reactions (ALTR) is a significant clinical problem in resurfacing and total hip arthroplasty. Retrieved periprosthetic tissue of 53 cases with corrosion/conventional metallic wear particles from 285 revision operations for ALTR was selected for nano-analyses. Three major classes of hip implants associated with ALTR, metal-on-metal hip resurfacing arthroplasty (MoM HRA) and large head total hip replacement (MoM LHTHA) and non-metal-on-metal dual modular neck total hip replacement (Non-MoM DMNTHA) were included. The size, shape, distribution, element composition, and crystal structure of the metal particles were analyzed by conventional histological examination and electron microscopy with analytic tools of 2D X-ray energy dispersive spectrometry and X-ray diffraction. Distinct differences in size, shape, and element composition of the metallic particles were detected in each implant class which correlate with the histological features of severity of ALTR and variability in implant performance. Copyright © 2016 The Authors. Published by Elsevier Inc. All rights reserved.

  1. The tribology of metal-on-metal total hip replacements.

    Science.gov (United States)

    Scholes, S C; Unsworth, A

    2006-02-01

    Total hip surgery is an effective way of alleviating the pain and discomfort caused by diseased or damaged joints. However, in the majority of cases, these joints have a finite life. The main reason for failure is osteolysis (bone resorption). It is well documented that an important cause of osteolysis, and therefore the subsequent loosening and failure of conventional metal- or ceramic-on-ultra-high molecular weight polyethylene joints, is the body's immunological response to the polyethylene wear particles. To avoid this, interest has been renewed in metal-on-metal joints. The intention of this paper is to review the studies that have taken place within different laboratories to determine the tribological performance of new-generation metal-on-metal total hip replacements. These types of joint offer a potential solution to enhance the longevity of prosthetic hip systems; however, problems may arise owing to the effects of metal ion release, which are, as yet, not fully understood.

  2. Metal-on-Metal Hip Retrieval Analysis: A Case Report

    OpenAIRE

    Pace, Thomas B.; Rusaw, Kara A.; Lawrence J. Minette; Brayton R. Shirley; Snider, Rebecca G.; John D. DesJardins

    2013-01-01

    This is a case report involving a single case with severe bone and soft tissue destruction in a young male patient with a 10-year-metal on-metal total hip arthroplasty. Following complete aseptic erosion of the affected hip greater trochanter and abductor muscles, the hip was revised for recurrent instability. Histological examination of the patient’s periprosthetic tissues, serological studies, and review of recent medical reports of similar cases were used to support an explanation of the d...

  3. Fatal Cobalt Toxicity after a Non-Metal-on-Metal Total Hip Arthroplasty

    Directory of Open Access Journals (Sweden)

    Rinne M. Peters

    2017-01-01

    Full Text Available This case illustrates the potential for systemic cobalt toxicity in non-metal-on-metal bearings and its potentially devastating consequences. We present a 71-year-old male with grinding sensations in his right hip following ceramic-on-ceramic total hip arthroplasty (THA. After diagnosing a fractured ceramic liner, the hip prosthesis was revised into a metal-on-polyethylene bearing. At one year postoperatively, X-rays and MARS-MRI showed a fixed reversed hybrid THA, with periarticular densities, flattening of the femoral head component, and a pattern of periarticular metal wear debris and pseudotumor formation. Before revision could take place, the patient was admitted with the clinical picture of systemic cobalt toxicity, supported by excessively high serum cobalt and chromium levels, and ultimately died. At autopsy dilated cardiomyopathy as cause of death was hypothesized. A third body wear reaction between ceramic remnants and the metal femoral head very likely led to excessive metal wear, which contributed systemic cobalt toxicity leading to neurotoxicity and heart failure. This case emphasizes that fractured ceramic-on-ceramic bearings should be revised to ceramic-on-ceramic or ceramic-on-polyethylene bearings, but not to metal-on-polyethylene bearings. We aim to increase awareness among orthopedic surgeons for clinical clues for systemic cobalt intoxication, even when there is no metal-on-metal bearing surface.

  4. Metal-on-Metal Total Hip Resurfacing Arthroplasty: An Evidence-Based Analysis.

    Science.gov (United States)

    2006-01-01

    The objective of this review was to assess the safety and effectiveness of metal on metal (MOM) hip resurfacing arthroplasty for young patients compared with that of total hip replacement (THR) in the same population. Total hip replacement has proved to be very effective for late middle-aged and elderly patients with severe degenerative diseases of the hips. As indications for THR began to include younger patients and those with a more active life style, the longevity of the implant became a concern. Evidence suggests that these patients experience relatively higher rates of early implant failure and the need for revision. The Swedish hip registry, for example, has demonstrated a survival rate in excess of 80% at 20 years for those aged over 65 years, whereas this figure was 33% by 16 years in those aged under 55 years. Hip resurfacing arthroplasty is a bone-conserving alternative to THR that restores normal joint biomechanics and load transfer. The technique has been used around the world for more than 10 years, specifically in the United Kingdom and other European countries. Metal-on-metal hip resurfacing arthroplasty is an alternative procedure to conventional THR in younger patients. Hip resurfacing arthroplasty is less invasive than THR and addresses the problem of preserving femoral bone stock at the initial operation. This means that future hip revisions are possible with THR if the initial MOM arthroplasty becomes less effective with time in these younger patients. The procedure involves the removal and replacement of the surface of the femoral head with a hollow metal hemisphere, which fits into a metal acetabular cup. Hip resurfacing arthroplasty is a technically more demanding procedure than is conventional THR. In hip resurfacing, the femoral head is retained, which makes it much more difficult to access the acetabular cup. However, hip resurfacing arthroplasty has several advantages over a conventional THR with a small (28 mm) ball. First, the large

  5. Metal on metal surface replacement of the hip. Experience of the McMinn prothesis.

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    McMinn, D; Treacy, R; Lin, K; Pynsent, P

    1996-08-01

    The historical failure of surface replacement has been due to the production of wear debris with subsequent bone resorption, loosening, and failure. To avoid these problems, a surface replacement using a metal on metal bearing allowing thin components and femoral design and instrumentation to avoid varus alignment has been designed. Two hundred thirty-five joints have been resurfaced with this prosthesis in almost 5 years. There have been no femoral neck fractures and no dislocations. There have been 4 designs differing in the method of fixation. In the press fit group, 6 of 70 hips had to be revised for aseptic loosening. In the cemented group, debonding of the cup occurred in 3 of 43 cases. Six patients had hydroxyapatite coated components and have had excellent clinical outcomes. The current design uses a peripherally expanded hydroxyapatite coated cup and a cemented metal head; 116 of this design have been implanted during a 19-month period with excellent outcome. Despite short followup the authors are hopeful that the combination of a polar metal on metal bearing with appropriate fixation will yield a method of preserving bone stock in the younger patient requiring arthroplasty.

  6. Elastohydrodynamic lubrication analysis of metal-on-metal hip-resurfacing prostheses.

    Science.gov (United States)

    Udofia, I J; Jin, Z M

    2003-04-01

    The elastohydrodynamic lubrication analysis was carried out in this study for a typical metal-on-metal hip-resurfacing prosthesis under a simple steady-state rotation. Both the Reynolds equation and the elasticity equation were coupled and solved numerically by the finite difference method. The finite element method was used to determine the elastic deformation of both the femoral and the acetabular components required for the lubrication analysis. The effect of the radial clearance between the femoral head and the acetabular cup on the predicted film thickness and pressure distribution was investigated. The predicted minimum lubricating film thickness was found to compare favourably with the prediction using the Hamrock and Dowson [J. Lubrication Technol. 100 (1978) 236] formula based on the assumption of ball-on-plane semi-infinite solids. This implies that the non-metallic materials such as bone and cement underlying the metallic components have a small effect on the predicted lubrication performance for the particular metal-on-metal hip-resurfacing prosthesis considered in this study. Under realistic physiological walking conditions, a decrease in the radial clearance from 150 to 50 microm resulted in a 137% increase in the predicted minimum film thickness from 19 to 45 nm. Consequently, given a surface roughness of 0.01 microm for both the metallic femoral and acetabular bearing surfaces, the predicted mixed lubrication regime for the larger clearance was changed to a full fluid film lubrication regime for the smaller clearance. This clearly highlighted the importance of the design and manufacturing parameters on the tribological performance of these hard-on-hard hip prostheses.

  7. Metal-on-metal hip resurfacings. A radiological perspective

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Zhongbo [University of Oxford, Medical School, Oxford (United Kingdom); Pandit, Hemant; Taylor, Adrian; Gill, Harinderjit; Murray, David [University of Oxford, Nuffield Department of Orthopaedic Surgery, Oxford (United Kingdom); Ostlere, Simon [Nuffield Orthopaedic Centre, Department of Radiology, Oxford (United Kingdom)

    2011-03-15

    It is important to be aware of the various complications related to resurfacing arthroplasty of the hip (RSA) and the spectrum of findings that may be encountered on imaging. The bone conserving metal-on-metal (MOM) hip resurfacing has become increasingly popular over the last ten years, especially in young and active patients. Initial reports have been encouraging, but long-term outcome is still unknown. Early post operative complications are rare and have been well documented in the literature. Medium and long term complications are less well understood. A rare but important problem seen at this stage is the appearance of a cystic or solid periarticular reactive mass, which occurs predominately in women and usually affects both hips when seen in patients with bilateral RSAs. The following imaging findings are illustrated and their significance discussed; Uncomplicated hip resurfacing arthroplasty, radiolucency around the femoral peg, femoral neck fracture, loosening and infection, suboptimal component position, femoral notching, dislocation, heterotopic ossification, femoral neck thinning and reactive masses. The radiologist should be aware of the normal radiographic appearances and the variety of complications that may occur following RSA and should recommend ultrasound or MRI in patients with an unexplained symptomatic hip and normal radiographs. (orig.)

  8. Comparative study of material loss at the taper interface in retrieved metal-on-polyethylene and metal-on-metal femoral components from a single manufacturer.

    Science.gov (United States)

    Bills, Paul; Racasan, Radu; Bhattacharya, Saugatta; Blunt, Liam; Isaac, Graham

    2017-08-01

    There have been a number of reports on the occurrence of taper corrosion and/or fretting and some have speculated on a link to the occurrence of adverse local tissue reaction specifically in relation to total hip replacement which have a metal-on-metal bearing. As such a study was carried out to compare the magnitude of material loss at the taper in a series of retrieved femoral heads used in metal-on-polyethylene bearings with that in a series of retrieved heads used in metal-on-metal bearings. A total of 36 metal-on-polyethylene and 21 metal-on-metal femoral components were included in the study all of which were received from a customer complaint database. Furthermore, a total of nine as-manufactured femoral components were included to provide a baseline for characterisation. All taper surfaces were assessed using an established corrosion scoring method and measurements were taken of the female taper surface using a contact profilometry. In the case of metal-on-metal components, the bearing wear was also assessed using coordinate metrology to determine whether or not there was a relationship between bearing and taper material loss in these cases. The study found that in this cohort the median value of metal-on-polyethylene taper loss was 1.25 mm3 with the consequent median value for metal-on-metal taper loss being 1.75 mm3. This study also suggests that manufacturing form can result in an apparent loss of material from the taper surface determined to have a median value of 0.59 mm3. Therefore, it is clear that form variability is a significant confounding factor in the measurement of material loss from the tapers of femoral heads retrieved following revision surgery.

  9. Clinical and Wear Analyses of 9 Large Metal-on-Metal Total Hip Prostheses.

    Science.gov (United States)

    Koper, M C; Mathijssen, N M C; Witt, F; Morlock, M M; Vehmeijer, S B W

    2016-01-01

    Metal-on-Metal (MoM) total hip arthroplasties (THA) are associated with pseudotumor formation and high revision rates. This prospective study analysed the clinical and wear analyses of 9 large Metal-on-Metal (MoM) total hip arthroplasties (THA) to understand the underlying mechanisms of failure. The MoM bearings were revised for multiple reasons; the main reason was pseudotumor formation. From 2006 till 2010 the Reinier de Graaf Hospital implanted 160 large head M2a-Magnum™ (Biomet Inc. Warsaw, Indiana, USA) THAs in 150 patients. The first year, 9 bearings were revised and analysed at the Biomechanics Section, Hamburg University of Technology, Germany. We performed clinical (Harris Hip Score, radiographic analysis, blood cobalt and chromium) and wear analysis (implant, tissue and fluid) of the 9 bearings. Since this study did not fall under the scope of the Medical Research Involving Human Subjects Act in The Netherlands, no ethical approval was necessary. In this prospective study all patient details were anonymized by the corresponding author, all other authors were blinded during the research and wear analyses. Patients with bilateral MoM implants were excluded. The 9 bearings had a median (IQR) survival of 41.0 (25) months in situ. From these bearings, three showed no noticeable wear. The median (IQR) head wear volume was 3.2 (3.6) mm3 and maximum wear depth 0.02 (0.02) mm. For the cup the median (IQR) wear volume was 0.23 (0.3) mm3 with a maximum wear depth of 0.03 (0.05) mm. An early identification of parameters related to failure of the MoM THA, such as pain, decreased range of motion, radiographic changes and high levels of blood cobalt and chromium is of great importance for patient's quality of life. Especially now patients and surgeons face the long term effects of all these bearings still in situ. This study reports the clinical and wear analyses of 9 MoM THA. In the majority of this group the reason for revision was pseudotumor formation. Most

  10. Predictive factors for metal ion levels in metal-on-metal total hip arthroplasty.

    Science.gov (United States)

    Kasparek, Maximilian F; Renner, Lisa; Faschingbauer, Martin; Waldstein, Wenzel; Weber, Michael; Boettner, Friedrich

    2018-02-01

    Although metal-on-metal (MoM) total hip arthroplasty (THA) and hip resurfacings (HR) have similar bearing surfaces and comparable wear rates, metal ion levels and risk of failure are higher for MoM-THA. The mechanism behind the increased metal ion levels in large head MoM-THA is not completely understood. The current study aims to identify predictive factors for increased metal ion levels in unilateral and bilateral large head MoM-THA. 99 Birmingham modular MoM-THA in 87 patients with metal ion levels at least 36 months after index procedure were analyzed. Mean follow-up time was 61.3 months (range 37-108) and the relationship of the following variables (gender, age, BMI, follow-up time, UCLA Activity Score, cup inclination, femoral head size, bilateral surgery) on metal ion levels were analyzed with multivariate regression models. Multivariate regression analysis revealed that bilateral MoM-THA surgery (p MoM-THA (p = 0.004) were positively correlated with chromium levels. Positive independent predictors for the cobalt-chromium ratio in the multivariate analysis were overall follow-up time (p = 0.004), bilateral MoM-THA (p MoM-THA, increased patient activity levels and female gender are associated with increased chromium levels. Patients with larger component size, longer follow-up time and bilateral MoM-THAs have an increased cobalt-chromium ratio. These patients might be at increased risk for adverse local soft tissue reactions secondary to corrosion. Continuous close monitoring is recommended and bearing-surface change should be discussed if local tissue reactions occur.

  11. Inflammatory pseudotumor causing deep vein thrombosis after metal-on-metal hip resurfacing arthroplasty.

    LENUS (Irish Health Repository)

    Memon, Adeel Rasool

    2013-01-01

    Metal-on-metal hip resurfacings have recently been associated with a variety of complications resulting from adverse reaction to metal debris. We report a case of extensive soft tissue necrosis associated with a huge pelvic mass causing extensive deep vein thrombosis of the lower limb secondary to mechanical compression of the iliac vein. This is a rare and unusual cause of deep vein thrombosis after metal-on-metal hip resurfacing arthroplasty.

  12. Surface Characterization of Retrieved Metal-on-Metal Total Hip Implants from Patients with Adverse Reaction to Metal Debris

    Directory of Open Access Journals (Sweden)

    Maria Burbano

    2014-03-01

    Full Text Available The use of metal-on-metal (MoM total hip implants has decreased recently due to reports of high failure rates and adverse local tissue reaction (ALTR. It has been hypothesized that wear metal debris released from CoCr bearing surfaces may provoke delayed hypersensitivity reactions. The goal of this study is to evaluate the microscopic bearing surface characteristics of implants revised due to evidence of ALTR. The bearing surface of each head and cup was analyzed using multiple microscopy techniques for characterization of the surface features. The presence of severe mechanical scratching was a common characteristic found in all of the implants evaluated. Mechanical factors seemed to be the prevalent failure mode related to the appearance of ALTR with this particular set of retrieved implants.

  13. Total hip arthroplasty in advanced osteonecrosis: the short-term results by metal-on-metal hip resurfacing.

    Science.gov (United States)

    Madadi, Firooz; Eajazi, Alireza; Kazemi, Seyyed Morteza; Aalami Harandi, Armin; Madadi, Firoozeh; Sharifzadeh, Seyyed Reza

    2011-02-01

    Characteristically, osteonecrosis affects younger patients who typically refer to the orthopedic surgeon for the first time in the third to fifth decades of life, in the late stages of the disease. Femoral metal-on-metal hip resurfacing is as an alternative to conventional total hip arthroplasty in treating osteoarthritis of the hip. Since there are already many reports regarding the successful outcome of resurfacing in advanced osteoarthritis, the purpose of this study was to analyze the clinical outcomes of this procedure in patients with osteonecrosis of the femoral head and to compare them with a matched group of patients with osteoarthritis. This retrospective cohort study evaluated a consecutive series of 52 patients with end-stage osteonecrosis (28 patients) and osteoarthritis (24 patients) of the femoral head, managed by metal-on-metal hip resurfacing in a referral orthopedic center from Feb 2002 to May 2007. Pain, function and deformity were evaluated with the use of the Harris hip score after the operation. Patients were clinically followed for a mean of 41 months. The patients in the osteoarthritis group had a significantly higher mean age than those in the osteonecrosis group (47.88 ± 12.6 vs 30.86 ± 7.5, p=0.003). The clinical outcomes were similar for both groups. There was no significant difference in mean Harris hip score (p=0.347) and hip joint range of motion (p=0.346) between osteonecrosis and osteoarthritis groups after surgery. On the basis of these initial findings, we recommend MOM resurfacing as a viable treatment option for patients with advanced stages of osteonecrosis.

  14. Metal-on-Metal Total Hip Arthroplasty: Quality of Online Patient Information.

    Science.gov (United States)

    Crozier-Shaw, Geoff; Queally, Joseph M; Quinlan, John F

    2017-03-01

    Metal-on-metal total hip arthroplasty (THA) has generated much attention in the media because of early failure of certain implant systems. This study assessed the quality, accuracy, and readability of online information on metal-on-metal THA. The search terms "metal-on-metal hip replacement" and "metal hip replacement" were entered into the 3 most popular search engines. Information quality was assessed with the DISCERN score and a specific metal-on-metal THA content score. Accuracy of information was assessed with a customized score. Readability of the websites was assessed with the Flesch-Kincaid grade level score. A total of 61 unique websites were assessed. For 56% of websites, the target audience was patients. Media or medicolegal sources accounted for 44% of websites. As assessed by DISCERN (range, 16-80) and metal-on-metal THA (range, 0-25) scores, quality of the websites was moderate at best (47.1 and 9.6, respectively). Accuracy (range, 0-8) of the information presented also was moderate, with a mean score of 6.6. Media and medicolegal websites had the lowest scores for both quality and accuracy, despite making up the greatest proportion of sites assessed. Only 1 website (2%) had a Flesch-Kincaid grade level at or less than the recommended level of 8th grade. This study found that online information on metal-on-metal THA was of poor quality, often was inaccurate, and was presented at an inappropriately high reading level, particularly for media and medicolegal websites. Health care providers should counsel patients on the quality of information available and recommend appropriate online resources. [Orthopedics. 2017; 40(2):e262-e268.]. Copyright 2016, SLACK Incorporated.

  15. Development and first validation of a simplified CT-based classification system of soft tissue changes in large-head metal-on-metal total hip replacement: intra- and interrater reliability and association with revision rates in a uniform cohort of 664 arthroplasties

    Energy Technology Data Exchange (ETDEWEB)

    Boomsma, Martijn F.; Warringa, Niek [Isala Hospital, Department of Radiology, Zwolle (Netherlands); Edens, Mireille A. [Isala Hospital, Department of Innovation and Science, Zwolle (Netherlands); Lingen, Christiaan P. van; Ettema, Harmen B.; Verheyen, Cees C.P.M. [Isala Hospital, Department of Orthopaedics, Zwolle (Netherlands); Maas, Mario [AMC, Department of Radiology, Amsterdam (Netherlands)

    2015-08-15

    After implantation of a metal-on-metal total hip arthroplasty (MoM THA), a large incidence of pseudotumor formation has been described recently. Several centers have invited patients for follow-up in order to screen for pseudotumor formation. The spectrum of abnormalities found by CT in MoM THA patients can be unfamiliar to radiologists and orthopedic surgeons. Previously, a CT five-point grading scale has been published. In this paper, a simplification into a three-point classification system gives insight in the morphological distinction of abnormalities of the postoperative hip capsule in MoM implants in relation to the decision for revision. The reliability of this simplified classification regarding intra- and interrater reliability and its association with revision rate is investigated and discussed. All patients who underwent MoM THA in our hospital were invited for screening. Various clinical measures and CT scan were obtained in a cross-sectional fashion. A decision on revision surgery was made shortly after screening. CT scans were read in 582 patients, of which 82 patients were treated bilaterally. CT scans were independently single read by two board-certified radiologists and classified into categories I-V. In a second meeting, consensus was obtained. Categories were subsequently rubricated in class A (categories I and II), B (category III), and C (categories IV and V). Intra- and inter-radiologist agreement on MoM pathology was assessed by means of the weighted Cohen's kappa. Categorical data were presented as n (%), and tested by means of Fisher's exact test. Continuous data were presented as median (min-max) and tested by means of Mann-Whitney U test (two group comparison) or Kruskal-Wallis test (three group comparison). Logistic regression analysis was performed in order to study independence of CT class for association with revision surgery. Univariate statistically significant variables were entered in a multiple model. All statistical

  16. Asymptomatic pseudotumours after metal-on-metal hip resurfacing show little change within one year

    NARCIS (Netherlands)

    van der Weegen, W.; Brakel, K.; Horn, R. J.; Hoekstra, H. J.; Sijbesma, T.; Pilot, P.; Nelissen, R. G. H. H.

    2013-01-01

    The aim of this study was to establish the natural course of unrevised asymptomatic pseudotumours after metal-on-metal (MoM) hip resurfacing during a six- to 12-month follow-up period. We used repeated metal artefact reduction sequence (MARS)-magnetic resonance imaging (MRI), serum metal ion

  17. Metal-on-metal hip arthroplasty : local tissue reactions and clinical outcome

    NARCIS (Netherlands)

    Weegen, Walter van der

    2014-01-01

    Hip replacements using a metal-on-metal (MoM) bearing surface were reintroduced with the promise of low wear rates and easy revision in case of the resurfacing design. Although initially mid-term results were promising, local adverse soft tissure reactions to metal debris were detected around the

  18. Complications Related to Metal-on-Metal Articulation in Trapeziometacarpal Joint Total Joint Arthroplasty

    DEFF Research Database (Denmark)

    Frølich, Christina; Hansen, Torben Bæk

    2015-01-01

    Adverse reactions to metal-on-metal (MoM) prostheses are well known from total hip joint resurfacing arthroplasty with elevated serum chrome or cobalt, pain and pseudo tumor formation. It may, however, also be seen after total joint replacement of the trapeziometacarpal joint using MoM articulation...

  19. Assessing the material loss of the modular taper interface in retrieved metal-on-metal hip replacements

    Science.gov (United States)

    Bills, Paul J.; Racasan, R.; Tessier, P.; Blunt, L. A.

    2015-06-01

    Measuring the amount of material loss in the case of revised hip replacements is considered to be a prerequisite of understanding and assessing the true in vivo performance of the implant. This paper outlines a method developed by the authors for quantifying taper material loss as well as more general taper interface parameters. Previous studies have mostly relied on visual inspection to assess the material loss at the taper interface, whereas this method aims to characterize any surface and form changes through the use of an out-of-roundness measurement machine. Along with assessing the volumetric wear, maximum linear penetration and taper contact length can also be determined. The method was applied to retrieved large head metal-on-metal femoral heads in order to quantify the material loss at this junction. Material loss from the female femoral head taper can be characterized as a localized area that is in contact with the stem taper surface. The study showed that this method has good repeatability and a low level of interoperability variation between operators.

  20. Cementless Total Hip Arthroplasty Involving Trochanteric Osteotomy without Subtrochanteric Shortening for High Hip Dislocation.

    Science.gov (United States)

    Lee, Soong Joon; Yoo, Jeong Joon; Kim, Hee Joong

    2017-03-01

    Total hip arthroplasty with subtrochanteric shortening osteotomy is widely performed for high hip dislocation. However, suboptimal leg length discrepancy correction and nonunion of the osteotomy site remain concerns. Although total hip arthroplasty using trochanteric osteotomy without subtrochanteric osteotomy was introduced, cemented implants have been more commonly used than contemporary cementless implants in this procedure. We evaluated the long-term results of cementless total hip arthroplasty with trochanteric osteotomy without subtrochanteric osteotomy for high hip dislocation. From 1990 to 2002, 27 cementless total hip arthroplasties using trochanteric osteotomy without subtrochanteric osteotomy were performed in 26 patients with Crowe III or IV high hip dislocation and a mean age of 36.4 ± 12.9 years. Seven ceramic-on-ceramic, 8 ceramic-on-polyethylene, 10 metal-on-polyethylene, and 2 metal-on-metal bearings were inserted. Mean follow-up was 15.1 ± 3.7 years. We retrospectively reviewed medical records and radiographic data and evaluated the clinical and radiological results including the Harris hip score, implant survival, correction of leg length discrepancy, and occurrence of complications. The mean Harris hip score and leg length discrepancy improved significantly from 73.3 to 94.9 points and from 4.3 cm to 1.0 cm, respectively. With revision for loosening set as the end point, implant survival rates at 10 and 15 years postoperatively were 96.0% and 90.9% for stems and 74.1% and 52.3% for cups. In 8 of 10 hips with the metal-on-polyethylene bearing and 4 of 8 hips with the ceramic-on-polyethylene bearing, revision surgery was performed for aseptic loosening. However, no revision was performed in hips with the ceramic-on-ceramic bearing or the metal-on-metal bearing. Implant survival was significantly different by the type of bearing surface. Two permanent neurologic complications occurred in patients with a limb lengthening over 3.5 cm. With proper

  1. Cementless Hydroxyapatite Coated Hip Prostheses

    Science.gov (United States)

    Herrera, Antonio; Mateo, Jesús; Gil-Albarova, Jorge; Lobo-Escolar, Antonio; Ibarz, Elena; Gabarre, Sergio; Más, Yolanda

    2015-01-01

    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. PMID:25802848

  2. 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.

  3. High Re-Operation Rates Using Conserve Metal-On-Metal Total Hip Articulations

    DEFF Research Database (Denmark)

    Mogensen, S L; Jakobsen, Thomas; Christoffersen, Hardy

    2016-01-01

    INTRODUCTION: Metal-on-metal hip articulations have been intensely debated after reports of adverse reactions and high failure rates. The aim of this study was to retrospectively evaluate the implant of a metal-on.metal total hip articulation (MOM THA) from a single manufacture in a two...... of 53 months. 4 pseudotumors were diagnosed at time of follow up but no substantiated link was made between adverse reactions and re-operations. CONCLUSION: The high re-operation rates found in this study raised concern about the usage of the MOM THA and subsequently lead to the termination......-center study. MATERIALS AND METHODS: 108 CONSERVE(®) MOM THA were implanted in 92 patients between November 2005 and December 2010. Patients had at time of retrospective evaluation their journals reviewed for re-operations and adverse reactions. RESULTS: 20 hips were re-operated (18.4%) at a mean follow up...

  4. Fatal Cobalt Toxicity after a Non-Metal-on-Metal Total Hip Arthroplasty

    OpenAIRE

    Peters, Rinne M.; Pax Willemse; Rijk, Paul C; Mels Hoogendoorn; Zijlstra, Wierd P

    2017-01-01

    This case illustrates the potential for systemic cobalt toxicity in non-metal-on-metal bearings and its potentially devastating consequences. We present a 71-year-old male with grinding sensations in his right hip following ceramic-on-ceramic total hip arthroplasty (THA). After diagnosing a fractured ceramic liner, the hip prosthesis was revised into a metal-on-polyethylene bearing. At one year postoperatively, X-rays and MARS-MRI showed a fixed reversed hybrid THA, with periarticular densiti...

  5. The effect of the metal-on-metal hip controversy on internet search activity.

    LENUS (Irish Health Repository)

    Phelan, Nigel

    2014-01-04

    The recall of the articular surface replacement (ASR) hip prosthesis in 2010 represents one of the most controversial areas in orthopaedic surgery in recent years. The aim of this study was to compare the impact of the metal-on-metal hip controversy on Internet search activity in four different regions and determine whether the number of related news reports affected Internet search activity. The Google Trends, Keywords and News applications were used to record the number of news articles and Internet search activity for the terms "hip recall", "metal-on-metal hip" and "ASR hip" from October 2009 to October 2012 in the USA, the UK, Australia and Ireland. There was a large increase in search activity following the official recall in August 2010 in all countries. There was significantly greater search activity after the recall in Ireland compared with the UK for the search term "hip recall" (P = 0.004). For the term "metal-on-metal hip", the UK had significantly more search activity (P = 0.0009). There was a positive correlation between the number of news stories in UK and Ireland with Internet search activity but not in the USA or Australia. Differences between countries affected by the same recall highlight the complex effects of the media on public awareness. The data demonstrates a window of opportunity prior to the official recall for the development of an awareness campaign to provide patients with accurate information.

  6. The effect of the metal-on-metal hip controversy on Internet search activity.

    Science.gov (United States)

    Phelan, Nigel; Kelly, John C; Moore, David P; Kenny, Patrick

    2014-10-01

    The recall of the articular surface replacement (ASR) hip prosthesis in 2010 represents one of the most controversial areas in orthopaedic surgery in recent years. The aim of this study was to compare the impact of the metal-on-metal hip controversy on Internet search activity in four different regions and determine whether the number of related news reports affected Internet search activity. The Google Trends, Keywords and News applications were used to record the number of news articles and Internet search activity for the terms "hip recall", "metal-on-metal hip" and "ASR hip" from October 2009 to October 2012 in the USA, the UK, Australia and Ireland. There was a large increase in search activity following the official recall in August 2010 in all countries. There was significantly greater search activity after the recall in Ireland compared with the UK for the search term "hip recall" (P = 0.004). For the term "metal-on-metal hip", the UK had significantly more search activity (P = 0.0009). There was a positive correlation between the number of news stories in UK and Ireland with Internet search activity but not in the USA or Australia. Differences between countries affected by the same recall highlight the complex effects of the media on public awareness. The data demonstrates a window of opportunity prior to the official recall for the development of an awareness campaign to provide patients with accurate information.

  7. Infection or metal hypersensitivity? The diagnostic challenge of failure in metal-on-metal bearings.

    LENUS (Irish Health Repository)

    Galbraith, John G

    2011-04-01

    The use of second generation metal-on-metal hip articulations has gained favour in the past few years. A hypersensitivity reaction to the metal-on-metal bearing, although rare, is a reported complication and is a novel mode of failure of these implants. Differentiating failure secondary to infection from failure secondary to metal hypersensitivity represents a significant diagnostic challenge. A retrospective review of all cases of hip arthroplasty using metal-on-metal bearings over a 5-year period at a tertiary referral centre identified 3 cases of failure secondary to metal hypersensitivity. Clinical presentation, serological markers, radiological imaging and histological analysis of all cases identified were evaluated. Histological analysis of periprosthetic tissue in all 3 cases identified characteristic features such as perivascular lymphocytic aggregates and chronic inflammation consistent with aseptic lymphocytic vasculitis-associated lesions (ALVAL). This study highlights that failure secondary to metal hypersensitivity must be considered in patients presenting with the reappearance of persistent pain, marked joint effusion, and the development of early osteolysis in the absence of infection.

  8. Revision rates for metal-on-metal hip resurfacing and metal-on-metal total hip arthroplasty – a systematic review

    DEFF Research Database (Denmark)

    Ras Sørensen, Sofie-amalie L.; Jørgensen, Henrik L.; Sporing, Sune L.

    2016-01-01

    Purpose To compare revision rates of metal-on-metal (MoM) hip resurfacing (HRS) and MoM total hip arthroplasty (THA), as well as the primary causes for revisions. Methods The PubMed database was queried for potentially relevant articles addressing MoMTHA and MoMHRS, a total of 51 articles were...... cause for revision for both MoMTHA and MoMHRS was loosening 47.6% vs. 37.7%, fracture (MoMTHA 7.69%; MoMHRS 19.62%), metal reactions (MoMTHA 7.69%; MoMHRS 26.92%) infection (MoMTHA 12.08%; MoMHRS 6.54%), instability (MoMTHA 9.13%; MoMHRS 2.69%), manufacturer defect 6.73% for MoMTHA and nonreported...... in revision rate of MoMHRS may indicate a progression in failure....

  9. Clinical significance of corrosion of cemented femoral stems in metal-on-metal hips: a retrieval study.

    Science.gov (United States)

    Hothi, Harry S; Berber, Reshid; Panagiotopoulos, Andreas C; Whittaker, Robert K; Rhead, Camilla; Skinner, John A; Hart, Alister J

    2016-11-01

    The clinical significance of corrosion of cemented femoral stems is unclear. The purpose of this retrieval study was to: (1) report on corrosion at the stem-cement interface and (2) correlate these findings with clinical data. We analysed cemented stems (n = 36) composed of cobalt-chromium (CoCr) and stainless steel (SS) in a series of revised metal-on-metal hips. We performed detailed inspection of each stem to assess the severity of corrosion at the stem-cement interface using a scale of 1 (low) to 5 (severe). We assessed the severity of corrosion at each stem trunnion and measured wear rates at the head taper and bearing surfaces. We used non-parametric tests to determine the significance of differences between the CoCr and SS stems in relation to: (1) pre-revision whole blood Co and Cr metal ion levels, (2) trunnion corrosion, (3) bearing surface wear and (4) taper material loss. The corrosion scores of CoCr stems were significantly greater than SS stems (p corrosion. The median pre-revision Co levels of implants with CoCr stems were significantly greater than the SS stems (p corrosion of cemented femoral stems is a common finding at our retrieval centre; surgeons should consider corrosion of CoCr stems as a potential source of metal ions when revising a hip.

  10. Metal-on-Metal Hip Arthroplasty: A Review of Adverse Reactions and Patient Management

    Directory of Open Access Journals (Sweden)

    James Drummond

    2015-06-01

    Full Text Available Recent alarming joint registry data highlighting increased revision rates has prompted further research into the area of metal-on-metal hip replacements and resurfacings. This review article examines the latest literature on the topic of adverse reactions to metal debris and summarises the most up-to-date guidelines on patient management. Adverse reactions to metal debris can cause significant damage to soft tissue and bone if not diagnosed early. Furthermore, not every patient with an adverse reaction to metal debris will be symptomatic. As such, clinicians must remain vigilant when assessing and investigating these patients in order to detect failing implants and initiate appropriate management.

  11. Current Insights Regarding Metal-on-Metal Bearings for Hip Arthroplasty

    OpenAIRE

    Catherine Van Der Straeten

    2017-01-01

    Modern small diameter metal-on-metal (MoM) bearings for total hip arthroplasty (THA) have been developed in the nineteen-eighties to address the problem of polyethylene wear related osteolysis. Subsequently large diameter MoM hip resurfacings (HRA) were designed for young and active patients to preserve bone and avoid dislocation. Large diameter MoM THA were originally meant as an easy femoral component-only revision solution for femoral neck fractures in HRA, but were then advocated for prim...

  12. Wear of an experimental metal-on-metal artificial disc for the lumbar spine.

    Science.gov (United States)

    Lee, Jessica L; Billi, Fabrizio; Sangiorgio, Sophia N; McGarry, William; Krueger, David J; Miller, Peter T; McKellop, Harry; Ebramzadeh, Edward

    2008-03-15

    In vitro wear simulation. To determine the type and amount of wear produced by experimental metal-on-metal artificial discs for the lumbar spine. To minimize the amount of wear by changing the carbon content, clearance, and presence of a keel and notch. In contrast to the extensive number of hip joint replacement simulator studies examining the effects of individual design variables on wear, existing artificial lumbar disc wear publications have measured wear using only the final version of each product. That is, the effects of individual variables such as material, diameter, or clearance on wear of artificial discs are not known, even though the importance of such variables has been established in artificial hip wear studies. Experimental metal-on-metal artificial discs for the lumbar spine were tested in a 3-station, biaxial spine wear simulator designed and constructed by the investigators. Two versions of the implants were manufactured with differences in carbon content, clearance, and the presence of a keel. Additionally, implants were tested with or without a surgical notch. The wear rates of the experimental metal-on-metal lumbar discs in the current study ranged from 6.2 to 15.8 mm3/million cycles. However, changing the carbon content of the ball from low to high, decreasing the initial clearance, and eliminating the anteroposterior keel reduced the wear rate from 12.4 to 7.6 mm3/million cycles. Furthermore, removing the surgical notch reduced the wear rate from 7.6 to 6.2 mm3/million cycles. The surface damage was generally consistent with low lubrication and varying degrees of abrasive and fatigue wear, with impingement of nonbearing surfaces observed at 1.5 million cycles for the longer-term test. Although the implants tested in the current study were experimental, the results suggest that metal-on-metal lumbar discs have the potential to produce wear of this magnitude and mechanism in vivo. Therefore, careful consideration of individual design variables

  13. Effect of carbon ion implantation on the tribology of metal-on-metal bearings for artificial joints.

    Science.gov (United States)

    Koseki, Hironobu; Tomita, Masato; Yonekura, Akihiko; Higuchi, Takashi; Sunagawa, Sinya; Baba, Koumei; Osaki, Makoto

    2017-01-01

    Metal-on-metal (MoM) bearings have become popular due to a major advantage over metal-on-polymer bearings for total hip arthroplasty in that the larger femoral head and hydrodynamic lubrication of the former reduce the rate of wear. However, concerns remain regarding adverse reactions to metal debris including metallosis caused by metal wear generated at the taper-head interface and another modular junction. Our group has hypothesized that carbon ion implantation (CII) may improve metal wear properties. The purpose of this study was to investigate the wear properties and friction coefficients of CII surfaces with an aim to ultimately apply these surfaces to MoM bearings in artificial joints. CII was applied to cobalt-chromium-molybdenum (Co-Cr-Mo) alloy substrates by plasma source ion implantation. The substrates were characterized using scanning electron microscopy and a 3D measuring laser microscope. Sliding contact tests were performed with a simple geometry pin-on-plate wear tester at a load of 2.5 N, a calculated contact pressure of 38.5 MPa (max: 57.8 MPa), a reciprocating velocity of 30 mm/s, a stroke length of 60 mm, and a reciprocating cycle count of 172,800 cycles. The surfaces of the CII substrates were generally featureless with a smooth surface topography at the same level as untreated Co-Cr-Mo alloy. Compared to the untreated Co-Cr-Mo alloy, the CII-treated bearings had lower friction coefficients, higher resistance to catastrophic damage, and prevented the adhesion of wear debris. The results of this study suggest that the CII surface stabilizes the wear status due to the low friction coefficient and low infiltration of partner materials, and these properties also prevent the adhesion of wear debris and inhibit excessive wear. Carbon is considered to be biologically inert; therefore, CII is anticipated to be applicable to the bearing surfaces of MoM prostheses.

  14. Neuropsychiatric symptoms following metal-on-metal implant failure with cobalt and chromium toxicity.

    Science.gov (United States)

    Green, Ben; Griffiths, Emily; Almond, Solomon

    2017-01-24

    There were at least 31,171 metal-on-metal (MoM) hip implants in the UK between 2003 and 2011. Some of these were subject to failure and widescale recalls and revisions followed. This is a presentation of ten cases (mean age 60 years) where we evaluated neuropsychiatric morbidity following metal-on-metal hip implant failure and revision. Implants were ASR total hip replacement (acetabular implant, taper sleeve adaptor and unipolar femoral implants) performed between 2005 and 2009. This case series describes, for the first time, neuropsychiatric complications after revision where there has been cobalt and chromium toxicity. Pre-revision surgery, nine patients had toxic levels of chromium and cobalt (mean level chromium 338 nmol/l, mean cobalt 669.4 nmol/l). Depression assessment showed 9 of 9 respondents fulfilled the BDI criteria for depression and 3 of these were being treated. 7 of 9 patients showing short term memory deficit with mean mini mental state examination score of 24.2. The normal population mean MMSE for this group would be expected to be 28 with chromium metallosis following MoM implant failure. Larger studies of neurocognitive effects are indicated in this group. There may be implications for public health.

  15. Prediction of contact mechanics in metal-on-metal Total Hip Replacement for parametrically comprehensive designs and loads.

    Science.gov (United States)

    Donaldson, Finn E; Nyman, Edward; Coburn, James C

    2015-07-16

    Manufacturers and investigators of Total Hip Replacement (THR) bearings require tools to predict the contact mechanics resulting from diverse design and loading parameters. This study provides contact mechanics solutions for metal-on-metal (MoM) bearings that encompass the current design space and could aid pre-clinical design optimization and evaluation. Stochastic finite element (FE) simulation was used to calculate the head-on-cup contact mechanics for five thousand combinations of design and loading parameters. FE results were used to train a Random Forest (RF) surrogate model to rapidly predict the contact patch dimensions, contact area, pressures and plastic deformations for arbitrary designs and loading. In addition to widely observed polar and edge contact, FE results included ring-polar, asymmetric-polar, and transitional categories which have previously received limited attention. Combinations of design and load parameters associated with each contact category were identified. Polar contact pressures were predicted in the range of 0-200 MPa with no permanent deformation. Edge loading (with subluxation) was associated with pressures greater than 500 MPa and induced permanent deformation in 83% of cases. Transitional-edge contact (with little subluxation) was associated with intermediate pressures and permanent deformation in most cases, indicating that, even with ideal anatomical alignment, bearings may face extreme wear challenges. Surrogate models were able to accurately predict contact mechanics 18,000 times faster than FE analyses. The developed surrogate models enable rapid prediction of MoM bearing contact mechanics across the most comprehensive range of loading and designs to date, and may be useful to those performing bearing design optimization or evaluation. Published by Elsevier Ltd.

  16. Cardiac cobaltism: a rare complication after bilateral metal-on-metal total hip arthroplasty

    Directory of Open Access Journals (Sweden)

    John R. Martin, MD

    2015-12-01

    Full Text Available This is one of the first documented cases of metal-on-metal (MoM total hip arthroplasty cobalt cardiac toxicity that has led to patient death. A 69-year-old female presented to our institution with cardiac failure secondary to cobalt toxicity resulting from bilateral MoM total hip arthroplasty. Her presenting metal ion levels were a cobalt level of 199 ppb and a chromium level of 77 ppb. She underwent bilateral femoral revisions to remove the source of cobalt. On postoperative day 7, the patient sustained a cerebral infarct and eventually expired because of the insult. This case represents one of the first documented fatalities related to MoM cobalt cardiac toxicity.

  17. [Measurement of chromium and cobalt ions in metal-on-metal total hip arthroplasty].

    Science.gov (United States)

    Durazo-Villanueva, A; Benítez-Garduño, R

    2012-01-01

    New metal-on-metal hip replacement models emerged in the 1990 with modifications of the previous designs and alloys. This led to expect a lesser rate of ion and particle release in the body with the resulting decrease in wear, osteolysis and loosening. To measure blood and urine chromium and cobalt ions in a 28 mm metal-on-metal tribology during the first postoperative year. Blood and urine cobalt and chromium concentrations were measured in 10 patients (13 prostheses) with the atomic absorption method. The etiology was studied and they were functionally assessed with the Harris functional scale. Adverse metal reactions were also assessed. 8 male and 2 female patients, mean age 54.5 years; 6 had primary coxarthrosis, one was post-traumatic, and 3 had avascular necrosis. The final assessment according to the Harris scale was 92 points. Mean blood chromium was 1.26 ng/l, blood cobalt was 1.033 microg/l; (reference values: chromium 1.4 ng/l and cobalt 1.8 microg/l); only one figure, in a female patient, was found to be higher than normal (chromium 21.2 ng/l and cobalt 15.4 microg/l). Mean urine chromium was 0.95 ng/ml, urine cobalt was 0.53 microg/l (Reference values: chromium: 2.0 ng/ml and cobalt 0.5 microg/l). All patients, with the exception of a female patient, were within the normal ranges. No adverse effect was observed in patients with metal implants with a 28 mm tribology.

  18. Chromium and cobalt ion concentrations in blood and serum following various types of metal-on-metal hip arthroplasties

    DEFF Research Database (Denmark)

    Jantzen, Christopher; Jørgensen, Henrik L; Duus, Benn R

    2013-01-01

    Widely different metal ion concentrations in blood and serum have been reported with metal-on-metal (MoM) implants. We reviewed the literature on blood and serum ion concentrations of chromium (Cr) and cobalt (Co) following various MoM hip arthroplasties.......Widely different metal ion concentrations in blood and serum have been reported with metal-on-metal (MoM) implants. We reviewed the literature on blood and serum ion concentrations of chromium (Cr) and cobalt (Co) following various MoM hip arthroplasties....

  19. Total hip replacement in an alpaca using a cementless implant.

    Science.gov (United States)

    Schulz, Kara L; Roush, James K; Anderson, David E; Hoots, Eric

    2009-01-01

    To report use of a cementless total hip prosthesis in an alpaca. Case report. Alpaca (n=1) with chronic craniodorsal coxofemoral luxation. A 2.5-year-old Suri alpaca, 3 months pregnant, was admitted for evaluation of acute onset severe left hind limb lameness (grade 4/5) of 6 weeks duration. After diagnosis of craniodorsal luxation of the left femoral head, total hip replacement (THR) using a cementless implant was performed because of the poor prognosis for reduction of a chronic luxation. A press-fit prosthesis was used and the alpaca delivered a live cria 8 months later. Persistent mild mechanical lameness remained after surgery, with moderate reduction in mobility of the coxofemoral joint. The prosthesis was stable and correctly positioned at 7 weeks and at 9 months. There was mild exostosis surrounding the proximal aspect of the femur at 9 months, and Steinmann pins used to repair the trochanteric osteotomy were removed because of migration. At 1 year, the alpaca has a slight gait abnormality, remains with the herd on pasture and has been re-bred. Chronic coxofemoral luxation in an alpaca can be managed by THR. THR is a viable treatment option in alpacas with severe coxofemoral disease.

  20. Patients with metal-on-metal articulation in trapeziometacarpal total joint arthroplasty may have elevated serum chrome and cobalt.

    Science.gov (United States)

    Hansen, T B; Dremstrup, L; Stilling, M

    2013-10-01

    Serum chrome and cobalt was measured in 50 patients with trapeziometacarpal total joint replacement with metal-on-metal articulation and compared with serum chrome and cobalt values in 23 patients with trapeziometacarpal total joint replacement with metal-on-polyethylene articulation. In 10 of 50 (20%) patients with metal-on-metal articulation, slightly elevated serum chrome or cobalt values were found compared with only one in 23 (4%) patients with metal-on-polyethylene articulation. All metal values were lower than accepted 'normal values' for metal-on-metal hip arthroplasty and so considered not to be a general health risk. However, the mean disabilities of the arm, shoulder and hand (DASH) score was 24 in patients with elevated serum chrome or cobalt compared with 10 in patients with normal metal values (p chrome or cobalt values. We recommend that patients with trapeziometacarpal total joint replacement with metal-on-metal articulation are followed with DASH score and radiological examination every 3-5 years and serum chrome and cobalt should be analysed in symptomatic cases to learn more about possible local complications leading to, or arising from, metal debris.

  1. Metal-on-metal bearings in total hip arthroplasties : Influence of cobalt chromium ions on bacterial growth and biofilm formation

    NARCIS (Netherlands)

    Hosman, Anton H.; van der Mei, Henny C.; Bulstra, Sjoerd K.; Busscher, Henk J.; Neut, Danielle

    2009-01-01

    Metal-on-metal (MOM) bearings involving cobalt-chromium (Co-Cr) alloys in total hip arthroplasties are becoming more and more popular due to their low wear. Consequences of corrosion products of Co-Cr alloys are for the most part unclear, and the influence of cobalt and chromium ions on biofilm

  2. No Superiority of Cemented Metal-on-Metal vs Metal-on-Polyethylene THA at 5-Year Follow-up

    NARCIS (Netherlands)

    Zijlstra, Wierd P.; Cheung, John; Sietsma, Maurits S.; van Raay, Jos J. A. M.; Deutman, Robert

    A randomized controlled trial was performed to compare the cemented Stanmore metal-on-metal (Biomet, Warsaw, Indiana) total hip arthroplasty (THA; 102 hips) to the cemented Stanmore metal-on-polyethylene (Biomet) THA (98 hips). The primary outcome was clinical performance. Radiological performance,

  3. Heavy reading in heavy metal : Unraveling the mystery of hip tissue in metal on metal total hip arthroplasty

    NARCIS (Netherlands)

    Boomsma, M.F.

    2017-01-01

    In this thesis, we investigated the use of computer tomography (CT) for the screening of patients with a metal-on-metal (MoM) hip prosthesis in two patient cohorts. With a self-established CT grading scale, we have shown that CT is a reliable method for the diagnosis of postoperative pathological

  4. Large fixed-size metal-on-metal total hip arthroplasty : higher serum metal ion levels in patients with pain

    NARCIS (Netherlands)

    Smeekes, Christiaan; Ongkiehong, Bastiaan; van der Wal, Bart; Wolterbeek, Ron; Henseler, Jan Ferdinand; Nelissen, Rob

    2015-01-01

    Purpose: Recently, concerns have arisen about metal-on-metal (MoM) total hip arthroplasty (THA). Therefore, the purpose of this cross-sectional cohort study was to describe the incidence of pain, pseudotumours, revisions and the relation between elevated metal ion levels, functional outcome and

  5. Balancing innovation and medical device regulation: the case of modern metal-on-metal hip replacements

    Directory of Open Access Journals (Sweden)

    Howard JJ

    2016-08-01

    Full Text Available Jason J Howard1,2 1Division of Orthopedic Surgery, Department of Surgery, Sidra Medical and Research Center, 2Department of Orthopedic Surgery, Weill Cornell Medical College, Doha, Qatar Abstract: Due to problems with wear particle generation and subsequent loosening using conventional metal-on-polyethylene total hip replacements, there has been a shift toward alternative bearing systems, including metal-on-metal (MoM, for younger, more active patients with degenerative joint disease. Based on positive results from early short-term clinical studies, MoM hip replacements were readily adopted by orthopedic surgeons with thousands being implanted worldwide over the past decade. Unacceptably high revision rates reported by two national joint registries called into question the rigorousness of the regulatory approval process for these implants, particularly with respect to premarket data requirements to prove safety, effectiveness, and the appropriateness of the regulatory pathway chosen. The purpose of this review was to investigate the balance between facilitating the introduction of new medical technologies and the need to ensure safety and effectiveness through comprehensive regulatory assessment. The case of MoM hip replacement devices was used to frame the investigation and subsequent discussions. The regulatory approval processes and post-market surveillance requirements associated with three common MoM hip replacements (two resurfacings: the Birmingham and articular surface replacement and the articular surface replacement XL total hip replacement were investigated. With respect to modern MoM hip replacement devices, the balance between facilitating the introduction of these new medical technologies and the need to ensure safety and effectiveness through comprehensive regulatory assessment was not achieved. The lessons learned from these experiences have application beyond joint replacements to the introduction of new medical technologies in

  6. Current Insights Regarding Metal-on-Metal Bearings for Hip Arthroplasty

    Directory of Open Access Journals (Sweden)

    Catherine Van Der Straeten

    2017-09-01

    Full Text Available Modern small diameter metal-on-metal (MoM bearings for total hip arthroplasty (THA have been developed in the nineteen-eighties to address the problem of polyethylene wear related osteolysis. Subsequently large diameter MoM hip resurfacings (HRA were designed for young and active patients to preserve bone and avoid dislocation. Large diameter MoM THA were originally meant as an easy femoral component-only revision solution for femoral neck fractures in HRA, but were then advocated for primary THA as well. In the last decade however, increasing numbers of revisions for adverse local tissues reactions (ALTR to metal debris have been reported. These ALTR are due to excessive wear of the MoM bearings, usually related to malpositioning of the components leading to edge loading, or in rare cases to metal sensitivity. Besides the immunological reactions, metal particles and ions have a potential local and systemic toxicity. Wear and tribocorrosion at the taper-trunnion connections of MoM THA but also THA with polyethylene and ceramic bearings have also been recognized as a cause of ALTR with extensive tissue destruction. Despite the fact that the long-term survivorship and functional results of certain MoM HRA are excellent and better than THA in the young and active patients group, MoM bearings have become very unpopular and are likely to be replaced by bearing couples of other materials.

  7. Natural Remission of Major Periprosthetic Osteolysis following Total Hip Arthroplasty with Metal-on-Metal Bearings

    Directory of Open Access Journals (Sweden)

    Tatsuya Tamaki

    2017-01-01

    Full Text Available The natural course of adverse events following the use of metal-on-metal (MoM bearings in total hip arthroplasty (THA is not well known. In this article, we report the case of a patient with asymptomatic major acetabular osteolysis following MoM THA that diminished gradually without any surgical intervention. A 58-year-old male underwent one-stage bilateral MoM THA for bilateral osteoarthritis. Four years after THA, major acetabular osteolysis developed in his right hip without any local or systemic symptoms. The patient underwent a careful radiographic and clinical observation without any surgical intervention because he did not want to undergo revision surgery. The lesion gradually diminished after 7 years, and most of the osteolytic area was replaced by newly formed bone at 10 years. He continues to be followed with no evidence of cup loosening or migration. Our observation suggests that a periprosthetic osteolytic change related to the use of MoM bearings has the potential for natural remission.

  8. Management guidelines for metal-on-metal hip resurfacing arthroplasty: A strategy on followup

    Directory of Open Access Journals (Sweden)

    Naoki Nakano

    2017-01-01

    Full Text Available Despite the initial promise of metal-on-metal (MoM implants as the ideal bearing surface for hip replacements and resurfacings, high short term failure rates due to an adverse reaction to metal debris (ARMD have led to a dramatic reduction in the number of MoM implants used in the modern era. With over one million patients worldwide having undergone hip operations utilizing a MoM bearing surface, the long term outcomes for such patients remains unknown, and there is much debate as to the most effective management of these patients. Although several regulatory bodies have released guidelines on the management of patients with MoM hips, these recommendations remain open to interpretation, and the most effective management for these patients remains unclear. The aim of this review is to compare the current guidelines for managing patients with MoM hips and also to discuss established ARMD risk factors, evidence regarding the optimum management for patients with MoM hips, and the indications for revision surgery. Furthermore, although specialized laboratory tests and imaging can be used to facilitate clinical decision making, over-reliance on any single tool should be avoided in the decision making process, and surgeons should carefully consider all findings when determining the most appropriate course of action.

  9. Histological characterization of periprosthetic tissue responses for metal-on-metal hip replacement

    Science.gov (United States)

    Phillips, Eual A.; Klein, Gregg R.; Cates, Harold E.; Kurtz, Steven M.; Steinbeck, Marla J.

    2014-01-01

    The histology of periprosthetic tissue from metal-on-metal (MOM) hip devices has been characterized by a variety of methods. The purpose of this study was to compare and evaluate the suitability of two previously developed aseptic lymphocyte-dominated vasculitis-associated lesions (ALVAL) scoring systems for periprosthetic hip tissue responses retrieved from MOM THR systems revised for loosening. Two ALVAL scoring systems (Campbell and Oxford) were used to perform histological analysis of soft tissues from seventeen failed MOM THRs. The predominant reactions for this patient cohort were macrophage infiltration and necrosis, with less than half of the patients (41%) showing a significant lymphocytic response or a high ALVAL reaction (6%). Other morphological changes which varied among patients included hemosiderin accumulation, cartilage formation and heterotopic ossification. Both scoring systems correlated with macrophage and lymphocyte responses and with each other, however given the diversity and variability of the current responses the Oxford-ALVAL system was more suitable for scoring tissues from MOM THR patients revised for loosening. It is important that standardized methods to score MOM tissue responses be used consistently so multiple study results can be compared to one another and a consensus can be generated. PMID:24941402

  10. The imaging spectrum of peri-articular inflammatory masses following metal-on-metal hip resurfacing

    Energy Technology Data Exchange (ETDEWEB)

    Fang, Christopher S.J.; Ostlere, Simon [Nuffield Orthopaedic Centre, Department of Radiology, Oxford (United Kingdom); Harvie, Paul; Gibbons, Christopher L.M.H.; Whitwell, Duncan [Nuffield Orthopaedic Centre, Department of Orthopaedic Surgery, Oxford (United Kingdom); Athanasou, Nicholas A. [Nuffield Orthopaedic Centre, Department of Pathology, Oxford (United Kingdom)

    2008-08-15

    Resurfacing metal-on-metal hip arthroplasty is increasing in popularity, especially in younger patients. To date, studies indicate that the procedure is associated with a good outcome in the medium-term. Formation of a peri-articuar mass is a rarely reported complication. In this study we analyse the imaging findings in patients with resurfacing implants presenting to our institution with peri-articular masses identified on cross sectional imaging. All patients with documented peri-articular masses following resurfacing arthroplasty were included. The available imaging related to the masses was reviewed and the findings documented along with the patient's demographics. There were 10 patients (13 joints). All patients were female. Patients presented with periprosthetic anterior or posterolateral solid and cystic masses. The anterior masses involved psoas muscle and were predominately solid. The posterolateral masses were predominately cystic. In the three cases with bilateral arthroplasties, masses were detected in both hips. Histology in six cases showed features compatible with a type IV hypersensitivity reaction. The preponderance of females, the bilateral nature of the masses and the histological features suggest that peri-articular masses following resurfacing arthroplasty is due to the metal hypersensitivity. (orig.)

  11. Tribolayer Formation in a Metal-on-Metal (MoM) Hip Joint: An Electrochemical Investigation

    Science.gov (United States)

    Mathew, MT; Nagelli, C; Pourzal, R; Fischer, A; Laurent, MP; Jacobs, JJ; Wimmer, MA

    2013-01-01

    The demand for total hip replacement (THR) surgery is increasing in the younger population due to faster rehabilitation and more complete restoration of function. Up to 2009, metal-on-metal (MoM) hip joint bearings were a popular choice due to their design flexibility, post-operative stability and relatively low wear rates. The main wear mechanisms that occur along the bearing surface of MoM joints are tribochemical reactions that deposit a mixture of wear debris, metal ions and organic matrix of decomposed proteins known as a tribolayer. No in-depth electrochemical studies have been reported on the structure and characteristics of this tribolayer or about the parameters involved in its formation. In this study, we conducted an electrochemical investigation of different surfaces (bulk-like: control, nano-crystalline: new implant and tribolayer surface: retrieved implant) made out of two commonly used hip CoCrMo alloys (high-carbon and low-carbon). As per ASTM standard, cyclic polarization tests and electrochemical impedance spectroscopy tests were conducted. The results obtained from electrochemical parameters for different surfaces clearly indicated a reduction in corrosion for the tribolayer surface (Icorr: 0.76 μA/cm2). Further, polarization resistance (Rp:2.39±0.60MΩ/cm2) and capacitance (Cdl:15.20±0.75 μF/cm2) indicated variation in corrosion kinetics for the tribolayer surface, that attributed to its structure and stability in a simulated body environment. PMID:24099949

  12. Bone remodeling around cementless tantalum cups

    NARCIS (Netherlands)

    Grillo, J. -C.; Flecher, X.; Bouvenot, J.; Argenson, J. -N.

    2008-01-01

    Purpose of the study.-Most studies have reported a significant decrease in periacetabular bone stock one year after implantation of a cementless cup. The purpose of this work was to study the bone-implant interface of the tantalum cup using plain X-rays and dual-energy X-ray absorptiometry (DEXA).

  13. Bone remodelling around a cementless glenoid component

    NARCIS (Netherlands)

    Suarez, D.R.; Weinans, H.; Van Keulen, F.

    2012-01-01

    Post-operative change in the mechanical loading of bone may trigger its (mechanically induced) adaptation and hamper the mechanical stability of prostheses. This is especially important in cementless components, where the final fixation is achieved by the bone itself. The aim of this study is,

  14. Bone remodelling around a cementless glenoid component

    NARCIS (Netherlands)

    D.R. Suárez (Daniel); H.H. Weinans (Harrie); F. van Keulen (Fred)

    2012-01-01

    textabstractPost-operative change in the mechanical loading of bone may trigger its (mechanically induced) adaptation and hamper the mechanical stability of prostheses. This is especially important in cementless components, where the final fixation is achieved by the bone itself. The aim of this

  15. Biomechanical evaluation of a metal-on-metal cervical intervertebral disc prosthesis.

    Science.gov (United States)

    Colle, Kyle O; Butler, John B; Reyes, Phillip M; Newcomb, Anna G U S; Theodore, Nicholas; Crawford, Neil R

    2013-11-01

    In vitro nondestructive flexibility testing of the CerviCore total disc replacement (TDR) was performed. It was hypothesized that TDR would not significantly alter biomechanics relative to intact, whereas rigid fixation would cause significant changes. To assess the ability of a cervical metal-on-metal saddle-shaped TDR to replicate normal biomechanics in vitro. Human cadaveric flexibility experiment. Nine human cadaveric C3-T1 specimens were tested intact, after TDR and after anterior plating. Flexion, extension, lateral bending, and axial rotation were induced by pure moments; flexion-extension was then repeated using a simplified muscle force model with 70-N follower load. Optical markers measured three-dimensional intervertebral motion, and eight points of laminar surface strain were recorded near the left and right C5-C6 facet joints. Biomechanical parameters studied included range of motion (ROM), lax zone (LZ), angular coupling pattern, sagittal instantaneous axis of rotation (IAR), and facet loads normal to the facet joint plane. Mean values of parameters were compared statistically using repeated measures analysis of variance and Holm-Sidak tests. Total disc replacement caused significant reduction in ROM during extension (p=.004) and significant reduction in LZ during lateral bending (p=.01). However, plating significantly reduced both ROM and LZ during flexion, extension, and lateral bending (p.05) and 6.5 mm after plating (p>.05). Coupled axial rotation/degree lateral bending was 99% of intact after TDR but 76% of intact after plating (p=.15). Coupled lateral bending/degree axial rotation was 95% of intact after TDR but 85% of intact after plating (p=.43). Neither construct altered facet loads from intact. With regard to ROM, LZ, IAR, and coupling, deviations from intact biomechanics were less substantial after TDR than after plating. Facet load alterations were minimal with either construct. Our results show that this particular TDR permits ROM and

  16. Longitudinal followup of incidentally detected pseudotumors in patients with metal on metal implants: A retrospective study

    Directory of Open Access Journals (Sweden)

    Khushboo Pilania

    2017-01-01

    Full Text Available Background: This study describes the significance and temporal evolution of incidentally detected, presumed, metal-induced reactive periprosthetic masses in patients with metal on metal (MoM hip arthroplasty and its management. The literature concerning the temporal evolution of these lesions is meagre and so it is still unclear, whether asymptomatic patients with periprosthetic collections should undergo revision. Materials and Methods: Patients with MoM hip replacements fitted with a recalled implant (ASR, DuPuy often undergo magnetic resonance imaging with metal artifact reduction sequences to look for complications. From a cohort of 136 asymptomatic patients, with 181 MoM hips, hips with a mention of periprosthetic masses in their reports at first presentation, and a repeat scan within 6 months to 3 years were selected for this retrospective study. Patients with complications such as loosening, osteomyelitis, and muscle/tendon tears were excluded from the study, and the final study cohort consisted of 55 MoM hips and 61 periprosthetic masses. Ethics committee approval is not required in our institution for retrospective studies. The followup scans of each patient were compared, and the periprosthetic masses were described to have progressed, regressed, or remained unchanged. Results: Comparison revealed that 29 of the 61 reactive masses remained unchanged, 20 regressed, while only 12 showed progression. The study, therefore, has maximum power as the outcome of interest, i.e., regression or unchanged status of the pseudotumors, was seen in approximately 80% (more than half of the study group. The P value of the study was < 0.005. Conclusion: Periprosthetic soft tissue masses are not uncommon in patients with MoM hips. The majority of them in asymptomatic individuals remain stable or regress in the short to medium term, and close followup or decisions on revision surgery may not be warranted in asymptomatic patients.

  17. Custom cementless THA in patients with Legg-Calve-Perthes Disease.

    Science.gov (United States)

    Al-Khateeb, Hesham; Kwok, Iris H Y; Hanna, Sammy A; Sewell, Mathew D; Hashemi-Nejad, Aresh

    2014-04-01

    Legg-Calve-Perthes disease is characterized by osteonecrosis of the femoral head during childhood. Outcomes of total hip arthroplasty (THA) for these patients are less satisfactory than for those with primary osteoarthritis, often complicated by young patient age, multi-planar deformities and previous childhood surgery. To our knowledge no one has reported the long-term outcomes of cementless custom-made THA in patients with Legg-Calve-Perthes disease. We reviewed 15 THAs with an average follow-up of ten years. Survivorship rates of the femoral and acetabular components were 100% and 79% respectively. Mean Harris Hip Scores improved from 41 preoperatively to 80 at final follow-up. With excellent functional outcome, custom-made cementless prostheses should be considered as a treatment option for osteoarthritis secondary to Legg-Calve-Perthes disease in the presence of abnormal proximal femoral and acetabular anatomy. © 2014.

  18. Microfocus study of metal distribution and speciation in tissue extracted from revised metal on metal hip implants

    Energy Technology Data Exchange (ETDEWEB)

    Hart, Alister J [Department of Orthopaedic Surgery, Imperial College and Imperial College Healthcare NHS Trust, Charing Cross Hospital Campus, Fulham Palace Rd, London W6 8RF (United Kingdom); Sandison, Ann [Department of Histopathology, Imperial College and Imperial College Healthcare NHS Trust, Charing Cross Hospital Campus, Fulham Palace Rd, London W6 8RF (United Kingdom); Quinn, Paul; Mosselmans, J Frederick W [Science Division, Diamond Light Source, Harwell Science and Innovation Campus, Didcot, Oxon, OX11 0DE (United Kingdom); Sampson, Barry [Department of Clinical Biochemistry, Imperial College and Imperial College Healthcare NHS Trust, Charing Cross Hospital Campus, Fulham Palace Rd, London W6 8RF (United Kingdom); Atkinson, Kirk D [8 Nuclear Department Defence Academy College of Management and Technology HMS Sultan Military Road Gosport PO12 3BY (United Kingdom); Skinner, John A [Department of Orthopaedics, Royal National Orthopaedic Hospital, HA7 4LP (United Kingdom); Goode, Angela [Dept of Materials, Imperial College London, SW7 2AZ (United Kingdom); Powell, Jonathan J, E-mail: Paul.Quinn@diamond.ac.u [Medical Research Council Human Nutrition Research Centre, Cambridge CB1 9NL (United Kingdom)

    2009-11-15

    Unexplained tissue inflammation in metal-on-metal hip replacements is suspected to be caused by implant-derived nanoparticles. The aim of this study was to investigate the nature of the metal particles in tissue surrounding metal-on-metal (MOM) hips that has been extracted during revision. Mapping of tissue surrounding the failed MOM hips was performed using microfocus X-ray Fluorescence (XRF). This revealed mainly Cr which was localized to the cellular regions. There was co-localisation of Co, were present, to areas of high Cr abundance. XANES of the tissue and appropriate standards revealed that the most common species were Cr(III) and Co(II). EXAFS analysis of the tissue and various metal standards revealed that the most abundant implant-related species was Cr(III) phosphate. Different tissue preparation methods, including frozen sectioning, were examined but were found not to affect the distribution or speciation of the metals in the tissue.

  19. Metal-on-metal total hip arthroplasty is not associated with cardiac disease.

    Science.gov (United States)

    Goodnough, L H; Bala, A; Huddleston, J; Goodman, S B; Maloney, W J; Amanatullah, D F

    2018-01-01

    Many case reports and small studies have suggested that cobalt ions are a potential cause of cardiac complications, specifically cardiomyopathy, after metal-on-metal (MoM) total hip arthroplasty (THA). The impact of metal ions on the incidence of cardiac disease after MoM THA has not been evaluated in large studies. The aim of this study was to compare the rate of onset of new cardiac symptoms in patients who have undergone MoM THA with those who have undergone metal-on-polyethylene (MoP) THA. Data were extracted from the Standard Analytics Files database for patients who underwent MoM THA between 2005 and 2012. Bearing surface was selected using International Classification of Diseases ninth revision codes. Patients with a minimum five-year follow-up were selected. An age and gender-matched cohort of patients who underwent MoP THA served as a comparison group. New diagnoses of cardiac disease were collected during the follow-up period. Comorbidities and demographics were identified and routine descriptive statistics were used. We identified 29 483 patients who underwent MoM THA and 24 175 matched patients who underwent MoP THA. Both groups had a mean Charlson comorbidity index score of 4. There were no statistically significant differences in 30 of 31 pre-existing comorbidities. Patients undergoing MoM THA had a slightly lower incidence of cardiac failure compared with those undergoing MoP THA at three years (6.60% versus 7.06%, odds ratio (OR) 0.93, 95% confidence interval (CI) 0.87 to 0.99) and four years (8.73% versus 9.49%, OR 0.91, 95% CI 0.86 to 0.97) postoperatively, with no difference in the incidence of new cardiac failure in between the groups at five years. There was no statistically significant difference in the incidence of arrhythmia, myocardial infarction and cardiomyopathy at any time between the two groups. MoM THA is not associated with cardiac complications. Initial reports may have represented individual instances of cardiac disease in patients

  20. Do cobalt and chromium levels predict osteolysis in metal-on-metal total hip arthroplasty?

    Science.gov (United States)

    Renner, Lisa; Schmidt-Braekling, Tom; Faschingbauer, Martin; Boettner, Friedrich

    2016-12-01

    Serum metal ions are part of the regular follow-up routine of patients with metal-on-metal total hip arthroplasties (MoM-THA). Increased cobalt levels have been suggested to indicate implant failure and corrosion. (1) Is there a correlation between the size of the osteolysis measured on a CT scan and metal ion levels? (2) Can metal ion levels predict the presence of osteolysis in MoM-THA? (3) Are cobalt and chromium serum levels or the cobalt-chromium-ratio diagnostic for osteolysis? CT scans of patients (n = 75) with a unilateral MoM-THA (Birmingham Hip System, Smith & Nephew, TN, USA) implanted by a single surgeon were reviewed to determine the presence of osteolysis. Statistical analysis was performed to detect its association with metal ion levels at the time of the imaging exam. The incidence of osteolysis was the same in men and women (35.6 vs 35.7 %). The cobalt-chromium-ratio correlates with the size of the osteolysis on the CT scan and the femoral component size in the overall study population (p = 0.050, p = 0.001) and in men (p = 0.002, p = 0.001) but not in women (p = 0.312, p = 0.344). The AUC for the cobalt-chromium-ratio to detect osteolysis was 0.613 (p = 0.112) for the overall population, 0.710 for men (p = 0.021) and 0.453 (p = 0.684) for women. The data suggest that a cut off level of 1.71 for the cobalt-chromium-ratio has a sensitivity of 62.5 % and specificity of 72.4 % to identify male patients with osteolysis. The disproportional increase of cobalt over chromium, especially in male patients with large component sizes can not be explained by wear alone and suggests that other processes (corrosion) might contribute to metal ion levels and might be more pronounced in patients with larger component sizes.

  1. Preoperative Risk Factors Associated With Poor Outcomes of Revision Surgery for "Pseudotumors" in Patients With Metal-on-Metal Hip Arthroplasty.

    Science.gov (United States)

    Liow, Ming Han Lincoln; Dimitriou, Dimitris; Tsai, Tsung-Yuan; Kwon, Young-Min

    2016-12-01

    Revision surgery of failed metal-on-metal (MoM) total hip arthroplasty (THA) for adverse tissue reaction (pseudotumor) can be challenging as a consequence of soft tissue and muscle necrosis. The aims of this study were to (1) report the revision outcomes of patients who underwent revision surgery for failed MoM hip arthroplasty due to symptomatic pseudotumor and (2) identify preoperative risk factors associated with revision outcomes. Between January 2011 and January 2013, a total of 102 consecutive large head MoM hip arthroplasties in 97 patients (male: 62, female: 35), who underwent revision surgery were identified from the database of a multidisciplinary referral center. At minimum follow-up of 2 years (range: 26-52 months), at least one complication had occurred in 14 of 102 revisions (14%). Prerevision radiographic loosening (P = .01), magnetic resonance imaging (MRI) findings of solid lesions with abductor deficiency on MRI (P Metal ion levels declined in most patients after removal of MoM articulation. Revision outcomes of revision surgery for failed MoM THA due to symptomatic pseudotumor demonstrated 14% complication rate and 7% re-revision rate at 30-month follow-up. Our study identified prerevision radiographic loosening, solid lesions/abductor deficiency on MRI, and high grade intraoperative tissue damage as risk factors associated with poorer revision outcomes. This provides clinically useful information for preoperative planning and perioperative counseling of MoM THA patients undergoing revision surgery. Copyright © 2016 Elsevier Inc. All rights reserved.

  2. Growth of an intrapelvic pseudotumor associated with a metal-on-metal total hip arthroplasty after revision arthroplasty causing a femoral nerve neuropathy

    OpenAIRE

    Leung, Patrick; Kudrna, James C.

    2016-01-01

    The development of pseudotumors is not uncommon with metal-on-metal total hip arthroplasty. Pseudotumors that dissect into the retroperitoneal space can cause symptoms of nerve compression. We describe a case of a 53-year-old male with a metal-on-metal total hip arthroplasty who developed mild symptoms of a femoral nerve neuropathy 6 years postoperatively. Revision arthroplasty to a ceramic-on-polyethylene articulation and debridement of the pseudotumor was performed. Postoperatively, the pat...

  3. Magnetic resonance imaging of metal artifact reduction sequences in the assessment of metal-on-metal hip prostheses

    Directory of Open Access Journals (Sweden)

    Aboelmagd SM

    2014-05-01

    Full Text Available Sharief M Aboelmagd, Paul N Malcolm, Andoni P Toms Department of Radiology, Norfolk and Norwich University Hospital National Health Service Trust, Norwich, UK Abstract: Recent developments in metal artifact reduction techniques in magnetic resonance (MR have, in large part, been stimulated by the advent of soft tissue complications associated with modern metal-on-metal total hip replacements. Metallic orthopedic implants can result in severe degradation of MR images because ferromagnetic susceptibility causes signal loss, signal pile-up, geometric distortion, and failure of fat suppression. There are several approaches to controlling these susceptibility artifacts. Standard fast spin echo sequences can be adapted by modifying echo times, matrix, receiver bandwidth, slice thickness, and echo trains to minimize frequency encoding misregistration. Short tau inversion recovery and 2-point Dixon techniques are both more resistant to susceptibility artifacts than spectral fat suppression. A number of dedicated metal artifact reduction sequences are now available commercially. The common approach of these multispectral techniques is to generate three dimensional datasets from which the final images are reconstructed. Frequency encoding misregistration is controlled using a variety of techniques, including specific resonant frequency acquisition, view-angle tilting, and phase encoding. Metal artifact reduction MR imaging has been the key to understanding the prevalence, severity, and prognosis of adverse reactions to metal debris in metal-on-metal hip replacements. Conventional radiographs are typically normal or demonstrate minimal change and are unable to demonstrate the often extensive soft tissue abnormalities, which include necrosis, soft tissue masses and fluid collections, myositis, muscle atrophy, tendon avulsions, and osteonecrosis. These MR findings correlate poorly with clinical and serological measures of disease, and therefore MR imaging is

  4. High blood metal ion levels in 19 of 22 patients with metal-on-metal hinge knee replacements

    OpenAIRE

    Laitinen, Minna; Nieminen, Jyrki; Reito, Aleksi; Pakarinen, Toni-Karri; Suomalainen, Piia; Pamilo, Konsta; Parkkinen, Jyrki; Lont, Tonis; Eskelinen, Antti

    2017-01-01

    Background and purpose There has been increasing alarm regarding metal-on-metal (MoM) joint replacements leading to elevated levels of metal ions and adverse reactions to metal debris (ARMDs). There is little information available concerning the prevalence of and risk factors for these adverse reactions, except with MoM hip joint replacements. We determined the levels of metal ions in blood and the rate of revision due to ARMDs in patients treated with MoM hinge total knee arthroplasty (TKA)....

  5. Increased Mortality in Metal-on-Metal versus Non-Metal-on-Metal Primary Total Hip Arthroplasty at 10 Years and Longer Follow-Up: A Systematic Review and Meta-Analysis.

    Science.gov (United States)

    Pijls, B G; Meessen, J M T A; Schoones, J W; Fiocco, M; van der Heide, H J L; Sedrakyan, A; Nelissen, R G H H

    2016-01-01

    There are concerns about increased mortality in patients with metal-on-metal bearings in total hip arthroplasty (THA). To determine the mortality and the morbidity in patients with metal-on-metal articulations (MOM THA) compared to patients with non-metal-on-metal articulations (non-MOM THA) after primary total hip arthroplasty. Search of PubMed, MEDLINE, EMBASE, Web of Science, Cochrane, CINAHL, AcademicSearchPremier, ScienceDirect, Wiley and clinical trial registers through March 2015, augmented by a hand search of references from the included articles. No language restrictions were applied. Two reviewers screened and identified randomised controlled trials and observational studies of primary total hip arthroplasty comparing MOM THA with non-MOM THA. Two reviewers independently extracted study data and assessed risk of bias. Risk differences (RD) were calculated with random effect models. Meta-regression was used to explore modifying factors. Difference in mortality and difference in morbidity expressed as revisions and medical complications between patients with MOM THA and non-MOM THA. Forty-seven studies were included, comprising 4,000 THA in randomised trials and over 500,000 THA in observational studies. For mortality, random effects analysis revealed a higher pooled RD of 0.7%, 95%, confidence interval (CI) [0.0%, 2.3%], I-square 42%; the heterogeneity was explained by differences in follow-up. When restricted to studies with long term follow-up (i.e. 10 years or more), the RD for mortality was 8.5%, 95%, CI [5.8%, 11.2%]; number needed to treat was 12. Further subgroup analyses and meta-regression random effects models revealed no evidence for other moderator variables (study level covariates, e.g. resurfacing vs. non-resurfacing MOM) than follow-up duration. The quality of the evidence presented in this meta-analysis was characterized as moderate according to the CLEAR-NPT (for non-pharmacological trials) and Cochrane risk of bias Table. Meta

  6. Increased Mortality in Metal-on-Metal versus Non-Metal-on-Metal Primary Total Hip Arthroplasty at 10 Years and Longer Follow-Up: A Systematic Review and Meta-Analysis.

    Directory of Open Access Journals (Sweden)

    B G Pijls

    Full Text Available There are concerns about increased mortality in patients with metal-on-metal bearings in total hip arthroplasty (THA.To determine the mortality and the morbidity in patients with metal-on-metal articulations (MOM THA compared to patients with non-metal-on-metal articulations (non-MOM THA after primary total hip arthroplasty.Search of PubMed, MEDLINE, EMBASE, Web of Science, Cochrane, CINAHL, AcademicSearchPremier, ScienceDirect, Wiley and clinical trial registers through March 2015, augmented by a hand search of references from the included articles. No language restrictions were applied.Two reviewers screened and identified randomised controlled trials and observational studies of primary total hip arthroplasty comparing MOM THA with non-MOM THA.Two reviewers independently extracted study data and assessed risk of bias. Risk differences (RD were calculated with random effect models. Meta-regression was used to explore modifying factors.Difference in mortality and difference in morbidity expressed as revisions and medical complications between patients with MOM THA and non-MOM THA.Forty-seven studies were included, comprising 4,000 THA in randomised trials and over 500,000 THA in observational studies. For mortality, random effects analysis revealed a higher pooled RD of 0.7%, 95%, confidence interval (CI [0.0%, 2.3%], I-square 42%; the heterogeneity was explained by differences in follow-up. When restricted to studies with long term follow-up (i.e. 10 years or more, the RD for mortality was 8.5%, 95%, CI [5.8%, 11.2%]; number needed to treat was 12. Further subgroup analyses and meta-regression random effects models revealed no evidence for other moderator variables (study level covariates, e.g. resurfacing vs. non-resurfacing MOM than follow-up duration. The quality of the evidence presented in this meta-analysis was characterized as moderate according to the CLEAR-NPT (for non-pharmacological trials and Cochrane risk of bias Table

  7. Metal-on-metal hip prostheses and systemic health: a cross-sectional association study 8 years after implantation.

    Directory of Open Access Journals (Sweden)

    Jennifer R Prentice

    Full Text Available There is public concern over the long term systemic health effects of metal released from hip replacement prostheses that use large-diameter metal-on-metal bearings. However, to date there has been no systematic study to determine which organs may be at risk, or the magnitude of any effect. We undertook a detailed cross-sectional health screen at a mean of 8 years after surgery in 35 asymptomatic patients who had previously received a metal-on-metal hip resurfacing (MoMHR versus 35 individually age and sex matched asymptomatic patients who had received a conventional hip replacement. Total body bone mineral density was 5% higher (mean difference 0.05 g/cm², P = 0.02 and bone turnover was 14% lower (TRAP 5b, mean difference -0.56IU/L, P = 0.006; osteocalcin, mean difference -3.08 ng/mL, P = 0.03 in the hip resurfacing versus conventional hip replacement group. Cardiac ejection fraction was 7% lower (mean absolute difference -5%, P = 0.04 and left ventricular end-diastolic diameter was 6% larger (mean difference 2.7 mm, P = 0.007 in the hip resurfacing group versus those patients who received a conventional hip replacement. The urinary fractional excretion of metal was low (cobalt 5%, chromium 1.5% in patients with MoMHR, but creatinine clearance was normal. Diuretic prescription was associated with a 40% increase in the fractional excretion of chromium (mean difference 0.5%, P = 0.03. There was no evidence of difference in neuropsychological, renal tubular, hepatic or endocrine function between groups (P>0.05. Our findings of differences in bone and cardiac function between patient groups suggest that chronic exposure to low elevated metal concentrations in patients with well-functioning MoMHR prostheses may have systemic effects. Long-term epidemiological studies in patients with well-functioning metal on metal hip prostheses should include musculoskeletal and cardiac endpoints to quantitate the risk of clinical disease.

  8. Case studies in management of THA failure secondary to taper corrosion, modular junctions and metal-on-metal bearings.

    Science.gov (United States)

    Lombardi, Adolph V

    2014-04-01

    The diagnosis and treatment of patients with painful total hip arthroplasties secondary to taper corrosion and wear of modular junctions and metal-on-metal bearings represents a major challenge for the orthopaedic clinician. Guidelines are evolving as we analyze the growing body of evidence regarding metal-related failures of orthopaedic implants and adverse reactions to metal debris. In this article 6 case examples are presented to enhance understanding and application of current evidence into practice. Clinical expertise is integrated with the best available evidence from research and national joint registries data into the decision making process relevant for patient care in everyday practice. Issues addressed include understanding taper corrosion and metal failure mechanisms, clinical presentation of adverse soft tissue reactions, utility of specialized tests such as metal ion analysis and cross-sectional imaging studies, the utility of modular components for primary THA, dealing with recalled component, and current recommendations. Copyright © 2014 Elsevier Inc. All rights reserved.

  9. Cobalt to Chromium Ratio is Not a Key Marker for Adverse Local Tissue Reaction (ALTR) in Metal on Metal Hips.

    Science.gov (United States)

    Fehring, Thomas K; Carter, Joshua L; Fehring, Keith A; Odum, Susan M; Griffin, William L

    2015-09-01

    The diagnosis of adverse local tissue reaction (ALTR) after metal-on-metal total hip arthroplasty (MoMTHA) presents a significant challenge. No single biomarker is specific for ALTR. The purpose of this study was to determine if the ratio of cobalt to chromium ions is useful for diagnosing ALTR in MoMTHA. In 89 bearing-related revision THAs, preoperative cobalt and chromium ion levels were compared to an intraoperative soft tissue damage grading scale. The average cobalt to chromium ratio was 2.96 (0-20). There was no correlation between the tissue scale and the cobalt to chromium ratio (R=0.095; P=0.41). Many variables affecting ion production/excretion mitigate the use of the ion ratio. The cobalt to chromium ratio is not a predictive biomarker for ALTR in MoMTHA. Copyright © 2015 Elsevier Inc. All rights reserved.

  10. Growth of an intrapelvic pseudotumor associated with a metal-on-metal total hip arthroplasty after revision arthroplasty causing a femoral nerve neuropathy

    Directory of Open Access Journals (Sweden)

    Patrick Leung, MD

    2016-09-01

    Full Text Available The development of pseudotumors is not uncommon with metal-on-metal total hip arthroplasty. Pseudotumors that dissect into the retroperitoneal space can cause symptoms of nerve compression. We describe a case of a 53-year-old male with a metal-on-metal total hip arthroplasty who developed mild symptoms of a femoral nerve neuropathy 6 years postoperatively. Revision arthroplasty to a ceramic-on-polyethylene articulation and debridement of the pseudotumor was performed. Postoperatively, the patient's femoral neuropathy progressed and a repeat magnetic resonance imaging showed an increase in size of the pseudotumor despite the removal of the offending metal-on-metal articulation. The patient subsequently underwent a laparoscopic excision of the retroperitoneal pseudotumor. By 17 months post laparoscopic excision of the pseudotumor, the patient's motor deficits resolved, however, sensory deficits persisted in the anteromedial thigh.

  11. Metal-on-metal total hip arthroplasty: risk factors for pseudotumours and clinical systematic evaluation.

    Science.gov (United States)

    Liow, Ming Han Lincoln; Kwon, Young-Min

    2017-05-01

    The potential advantages of contemporary MoM THA implants include less volumetric wear with subsequent reduction of polyethylene wear-induced osteolysis and greater component stability with use of large-diameter femoral heads. However, there have been concerns regarding significantly elevated revision rates in MoM THA due to MoM-related complications such as adverse local tissue reaction (pseudotumour) formation. The increased failure rate in MoM hip arthroplasty is associated with the generation of biologically active, nanometer sized metal particles from the MoM bearing surfaces and taper junctions, which result in the development of a localized, adverse periprosthetic soft tissue response. The focus of this article is to provide an update on (1) implant, surgical and patient factors associated with adverse local tissue reactions (pseudotumours) and (2) the clinical systematic evaluation and management of patients with MoM hip arthroplasty based on the currently available evidence. There should be a low threshold to conduct a systematic clinical evaluation of patients with MoM hip arthroplasty as early recognition and diagnosis will allow the initiation of prompt and appropriate treatment. As a symptomatic MoM total hip arthroplasty may have intrinsic and extrinsic causes, patients should be evaluated systematically, utilizing risk stratification algorithms. Although specialized laboratory tests such as metal ion levels and cross sectional imaging modalities such as MARS MRI can be used to facilitate clinical decision making, over-reliance on any single investigative tool in the clinical decision-making process should be avoided. Further research is required to obtain a better understanding of implant and patient risk factors associated with tribocorrosion in MoM total hip arthroplasty.

  12. Metal ion concentrations in body fluids after implantation of hip replacements with metal-on-metal bearing--systematic review of clinical and epidemiological studies.

    Directory of Open Access Journals (Sweden)

    Albrecht Hartmann

    Full Text Available INTRODUCTION: The use of metal-on-metal (MoM total hip arthroplasty (THA increased in the last decades. A release of metal products (i.e. particles, ions, metallo-organic compounds in these implants may cause local and/or systemic adverse reactions. Metal ion concentrations in body fluids are surrogate measures of metal exposure. OBJECTIVE: To systematically summarize and critically appraise published studies concerning metal ion concentrations after MoM THA. METHODS: Systematic review of clinical trials (RCTs and epidemiological studies with assessment of metal ion levels (cobalt, chromium, titanium, nickel, molybdenum in body fluids after implantation of metalliferous hip replacements. Systematic search in PubMed and Embase in January 2012 supplemented by hand search. Standardized abstraction of pre- and postoperative metal ion concentrations stratified by type of bearing (primary explanatory factor, patient characteristics as well as study quality characteristics (secondary explanatory factors. RESULTS: Overall, 104 studies (11 RCTs, 93 epidemiological studies totaling 9.957 patients with measurement of metal ions in body fluids were identified and analyzed. Consistently, median metal ion concentrations were persistently elevated after implantation of MoM-bearings in all investigated mediums (whole blood, serum, plasma, erythrocytes, urine irrespective of patient characteristics and study characteristics. In several studies very high serum cobalt concentrations above 50 µg/L were measured (detection limit typically 0.3 µg/L. Highest metal ion concentrations were observed after treatment with stemmed large-head MoM-implants and hip resurfacing arthroplasty. DISCUSSION: Due to the risk of local and systemic accumulation of metallic products after treatment with MoM-bearing, risk and benefits should be carefully balanced preoperatively. The authors support a proposed "time out" for stemmed large-head MoM-THA and recommend a restricted

  13. Cost-utility of metal-on-metal hip resurfacing compared to conventional total hip replacement in young active patients with osteoarthritis

    NARCIS (Netherlands)

    Heintzbergen, S.; Kulin, N.A.; IJzerman, Maarten Joost; Steuten, Lotte Maria Gertruda; Werle, J.; Khong, H.; Marshall, D.A.

    2013-01-01

    Background: Metal-on-metal hip resurfacing arthroplasty (MoM HRA) has emerged as an alternative to total hip arthroplasty (THA) for younger active patients with osteoarthritis (OA). Birmingham hip resurfacing is the most common MoM HRA in Alberta, and is therefore compared with conventional THA.

  14. Acetabular bone density and metal ions after metal-on-metal versus metal-on-polyethylene total hip arthroplasty; short-term results

    NARCIS (Netherlands)

    Zijlstra, Wierd P.; van der Veen, Hugo C.; van den Akker-Scheek, Inge; Zee, Mark J. M.; Bulstra, Sjoerd K.; van Raay, Jos J. A. M.

    Information on periprosthetic acetabular bone density is lacking for metal-on-metal total hip arthroplasties. These bearings use cobalt-chromium instead of titanium acetabular components, which could lead to stress shielding and hence periprosthetic bone loss. Cobalt and chromium ions have

  15. Scoring the Current Risk Stratification Guidelines in Follow-up Evaluation of Patients After Metal-on-Metal Hip Arthroplasty: A Proposal for a Metal-on-Metal Risk Score Supporting Clinical Decision-Making.

    Science.gov (United States)

    Hussey, Daniel K; Madanat, Rami; Donahue, Gabrielle S; Rolfson, Ola; Bragdon, Charles R; Muratoglu, Orhun K; Malchau, Henrik

    2016-11-16

    In the follow-up evaluation of patients with metal-on-metal (MoM) hip replacements, current evidence suggests that orthopaedic surgeons should avoid reliance on any single investigative tool. Current risk stratification guidelines can be difficult to interpret because they do not provide guidance when there are several risk factors in different groups (high and low risk). To improve the clinical utility of risk stratification guidelines, we designed a scoring system to assess the risk of revision. The study population consisted of 1,709 patients (1,912 hips) enrolled in a multicenter follow-up study of a recalled MoM hip replacement. Eleven scoring criteria were determined on the basis of existing follow-up algorithm recommendations and consisted of patient-related factors, symptoms, clinical status, implant type, metal ion levels, and radiographic imaging results. Forward stepwise logistic regression was conducted to determine the minimum set of predictive variables for the risk of revision and to assign variable weights. The MoM risk score for each hip was then created by averaging the weighted values of each predictive variable. Receiver operating characteristic curve analysis yielded good discrimination between all revised and unrevised hips, with an area under the curve of 0.82 (p clinical decision-making process. Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence. Copyright © 2016 by The Journal of Bone and Joint Surgery, Incorporated.

  16. MRI of early symptomatic metal-on-metal total hip arthroplasty: a retrospective review of radiological findings in 20 hips

    Energy Technology Data Exchange (ETDEWEB)

    Toms, A.P. [Department of Radiology, Norfolk and Norwich University Hospital, Norwich, Norfolk (United Kingdom)], E-mail: andoni.toms@nnuh.nhs.uk; Marshall, T.J.; Cahir, J. [Department of Radiology, Norfolk and Norwich University Hospital, Norwich, Norfolk (United Kingdom); Darrah, C.; Nolan, J. [Department of Orthopaedics, Norfolk and Norwich University Hospital, Norwich, Norfolk (United Kingdom); Donell, S.T. [Institute of Health, University of East Anglia, Norwich, Norfolk (United Kingdom); Barker, T. [Department of Pathology, Norfolk and Norwich University Hospital, Norwich, Norfolk (United Kingdom); Tucker, J.K. [Department of Orthopaedics, Norfolk and Norwich University Hospital, Norwich, Norfolk (United Kingdom)

    2008-01-15

    Aim: To perform a retrospective review of all the conventional radiographic and magnetic resonance imaging (MRI) studies performed in patients with early postoperative pain following cobalt-chrome metal-on-metal total hip arthroplasty. Methods: A retrospective review of the radiology, surgical findings and histology in nineteen patients who had undergone a total of 20 hip arthroplasties using a cobalt-chromium on cobalt-chromium alloy prosthesis was undertaken. Results: Measures of implant placement on the immediate postoperative radiographs were all within the normal ranges (n = 20). Where more than one postoperative radiograph was available statistical analysis revealed no evidence of progressive change before the MRI examination (14). The median postoperative time to MRI was 35 months (range 11-63 months). Abnormalities were demonstrated using MRI in all symptomatic hips (n = 20). These comprised: periprosthetic fluid collections (20), which were isointense to muscle on T1-weighted images in 19 cases and hyperintense on T2-weighted images in 18 cases, periprosthetic bone marrow oedema (n = 6), muscle oedema (n = 4), avulsion of the gluteus minimus and medius tendons (n = 5), atrophy of piriformis (n = 15) and obturator internus (n = 17), and fracture of the medial calcar (n = 1). Operative findings in patients who had undergone revision surgery (n = 15) included: fluid-filled cavities (n = 11), soft tissue necrosis (n = 8), gluteal tendon avulsion (n = 5), proximal femoral diaphyseal necrosis (n = 4), and pitting and corrosion of the femoral stems (n = 8), which were, in all cases, firmly fixed to the cement mantle. Histology revealed viable tissue in six hips with necrosis (n = 12) and fibrin deposition (n = 15) being the predominate findings. Other findings included a perivascular lymphocytic infiltrate (n = 5), features of active inflammation (n = 4), and metallosis (n = 1). Conclusion: A significant number of patients with metal-on-metal hip replacements

  17. Modified cementless total coxofemoral prosthesis: development, implantation and clinical evaluation

    Directory of Open Access Journals (Sweden)

    S.A. Arias

    2013-12-01

    Full Text Available The aim of this study was to modify canine coxofemoral prostheses and the clinical evaluation of the implantation. Fifteen canine hips and femora of cadavers were used in order to study the surface points of modification in prostheses and develop a perforation guide. Femoral stems and acetabular components were perforated and coated with biphasic calcium phosphate layer. Twelve young adult male mongrel dogs were implanted with coxofemoral prostheses. Six were operated upon and implanted with cemented canine modular hip prostheses, establishing the control group. The remaining six were implanted with a novel design of cementless porous tricalcic phosphate-hydroxyapatite coated hip prostheses. Clinical and orthopedic performance, complications, and thigh muscular hypotrophy were assessed up to the 120th post-operatory day. After 120 days, animals with cementless prostheses had similar clinical and orthopedic performance compared to the cemented group despite the increased pain thigh hypotrophy. Animals that underwent cementless hip prosthesis evidenced more pain, compared to animals with cemented hip prosthesis that required longer recuperation time. No luxations, two fractures and two isquiatic neurapraxies were identified in the course of the study. Using both the cemented and the bioactive coated cementless model were suitable to dogs, showing clinical satisfactory results. Osseointegration and biological fixation were observed in the animals with the modified cementless hip prosthesis.

  18. Migration pattern of a cobalt-chrome monoblock acetabular component after metal-on-metal hip resurfacing.

    Science.gov (United States)

    Roda, Richard; Whittingham-Jones, Paul M; Lee, Joshua; Ryu, Jae-Jin; Beaulé, Paul E

    2016-05-16

    The purpose of this study was to study the initial fixation and migration pattern of a monoblock acetabular component used for a metal on metal hip resurfacing using Einzel Bild Roentgen Analyse (EBRA). 99 patients with a mean age of 49.6 years (range 28.5-66.3 years) of whom 14 were bilateral underwent a hip resurfacing (Conserve Plus®, MicroPort, Memphis, TN) for a total of 113 resurfacings. Acetabular component orientation was noted with 35 of the 113 components (31.0%) having a lucency >2 mm on the immediate postoperative radiograph. The mean follow-up for our cohort of 113 hips is 50 months (2-79 months). When examining the 2-year migration mark, 37 of the 113 hips exceeded the threshold of 0.5 mm/year with a median total migration of 1.40 mm (range 1.02-4.24). 6 resurfacings underwent revision surgery for aseptic loosening of the acetabular component at a mean time of 43.6 months. Presence of initial lucency (OR 2.29, p = 0.05) was the only significant predictor of migration over threshold at 2-years. Those that had migrated over the threshold (1.0 mm) at 2 years were at significantly greater risk of continued migration at 4 years. The migration pattern of this component raises concerns about long term performance, with postoperative lucencies representing a significant factor for future migration.

  19. Uncemented metal-on-metal acetabular component: follow-up of 112 hips for a minimum of 5 years.

    Science.gov (United States)

    Vassan, Uma T; Sharma, Sanjeev; Chowdary, Koganti P; Bhamra, Manjit S

    2007-08-01

    Aseptic loosening is the major cause of implant failure. In cemented hip arthroplasty, failure of the acetabular side is mainly due to lysis caused by wear particles. By using an implant with low wear characteristics and by enhancing acetabular fixation using an uncemented implant, we aimed to reduce acetabular lysis and thereby loosening. This was a retrospective cohort study of 119 hips (101 patients) that had the Uncemented Fitmore cup (Sulzer Orthopedics). In 66 patients, the femoral component was CF-30 (Sulzer) used with cement. In the remaining 35 patients, thrust plate prosthesis (TPP) (Sulzer) was used. Of the 101 patients, 94 (112 hips) were available for study. Mean follow-up of the 94 patients was 7 (5-13) years. The mean preoperative Harris hip score was 38 and the mean postoperative Harris hip score was 89 at the last follow-up. Taking aseptic loosening as the endpoint, the survival rate of the Fitmore cup was 100% at 11 years. The uncemented Fitmore acetabular cup with second generation metal-on-metal articulation showed good results with regard to aseptic loosening in the medium term.

  20. MRI of asymptomatic patients with metal-on-metal and polyethylene-on-metal total hip arthroplasties

    Energy Technology Data Exchange (ETDEWEB)

    Mistry, A.; Cahir, J. [Department of Radiology, Norfolk and Norwich University Hospital, Norwich, Norfolk (United Kingdom); Donell, S.T.; Nolan, J. [Department of Orthopaedic Surgery, Norfolk and Norwich University Hospital, Norwich, Norfolk (United Kingdom); Toms, A.P., E-mail: andoni.toms@nnuh.nhs.u [Department of Radiology, Norfolk and Norwich University Hospital, Norwich, Norfolk (United Kingdom)

    2011-06-15

    Aims: To define and compare magnetic resonance imaging (MRI) findings of asymptomatic patients with metal-on-metal (MOM) and polyethylene-on-metal (POM) total hip replacements (THRs). Materials and methods: Twenty-two THRs in 20 asymptomatic patients (seven men, 13 women, mean age 68 years, range 47-86 years) with normal hip radiographs were included in the study. These comprised 10 POM and 12 MOM bearings. Each patient underwent MRI with metal artefact reduction sequences (MARS) at a mean time of 46 months (POM) and 70 months (MOM) after surgery. Two musculoskeletal radiologists independently read each MRI examination for fluid collections, soft-tissue masses, muscle atrophy, and bone marrow signal changes. Results: A pre-MRI hip radiograph showed no significant differences from the postoperative radiograph regarding acetabular inclination, femoral stem angle, and stem mantle grade. There were eight periprosthetic collections (one POM, seven MOM). The majority of THRs had normal gluteal muscles. The ipsilateral piriformis and obturator internus muscles were more frequently abnormal in the MOM group. Overall, there were no significant differences in the number of abnormalities between the two types of bearings. Conclusion: A range of MRI abnormalities are present in normal asymptomatic THRs but the increased frequency of these associated with MOM THR suggest that some of these changes might represent subclinical disease.

  1. Clinical usefulness of blood metal measurements to assess the failure of metal-on-metal hip implants

    Science.gov (United States)

    Sampson, Barry; Hart, Alister

    2012-01-01

    In April 2010, a Medicines and Healthcare Products Regulatory Agency safety alert concerning all metal-on-metal (MOM) hip replacements recommended measuring chromium and cobalt concentrations when managing patients with painful prostheses. The need for this review is illustrated by the recent surge in requests for these blood tests from orthopaedic surgeons following this alert. The aim is to provide guidance to laboratories in assessing these requests and advising clinicians on interpretation. First, we summarize the basic terminology regarding the types of hip replacements, with emphasis on the MOM type. Second, we describe the clinical concerns over implant-derived wear debris in the local tissues and distant sites. Analytical aspects of the measurement of the relevant metal ions and what factors affect the levels measured are discussed. The application of inductively coupled plasma mass spectrometry techniques to the measurement of these metals is considered in detail. The biological effects of metal wear products are summarized with local toxicity and systemic biological effects considered, including carcinogenicity, genotoxicity and systemic toxicity. Clinical cases are used to illustrate pertinent points. PMID:22155921

  2. A MRI classification of periprosthetic soft tissue masses (pseudotumours) associated with metal-on-metal resurfacing hip arthroplasty

    Energy Technology Data Exchange (ETDEWEB)

    Hauptfleisch, Jennifer; Ostlere, Simon [Nuffield Orthopaedic Centre, Oxford University Hospitals NHS Trust, Department of Radiology, Oxford (United Kingdom); Pandit, Hemant; Grammatopoulos, George; Gill, Harinderjit S.; Murray, David W. [Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences (NDORMS), University of Oxford, Botnar Research Centre, Oxford (United Kingdom)

    2012-02-15

    Metal-on-metal hip resurfacing arthroplasty (MoMHRA) has become a popular option for young patients requiring hip replacement. A recognised complication is the formation of a symptomatic reactive periprosthetic soft tissue mass (pseudotumour). We present a radiological classification system for these reactive masses, dividing them into three groups: Type I are thin-walled cystic masses (cyst wall <3 mm), Type II are thick-walled cystic masses (cyst wall >3 mm, but less than the diameter of the cystic component) and Type III are predominantly solid masses. We reviewed all MRI performed over a 4-year period in patients with primary MoMHRA referred to our institution. In all cases the masses were assessed on MRI according to size, anatomical position, signal intensity and involvement of bone, muscle or neighbouring neurovascular bundles. Periprosthetic masses were seen in 33 hips in 17 female (7 bilateral) and 8 male patients (1 bilateral). The Type I lesions were the most common and more likely to be posterior to the hip joint. The Type III masses were significantly larger than the cystic lesions and were more likely to be located anterior to the hip joint. To date 22 patients have undergone revision surgery with conversions to total hip replacement. Severity of symptoms and revision rates were lowest in the Type I group and highest in the Type III group. Solid anterior pseudotumours were most likely to have the more severe symptoms and require revision surgery. (orig.)

  3. International metal-on-metal multidisciplinary teams: do we manage patients with metal-on-metal hip arthroplasty in the same way? An analysis from the International Specialist Centre Collaboration on MOM Hips (ISCCoMH).

    Science.gov (United States)

    Berber, R; Skinner, J; Board, T; Kendoff, D; Eskelinen, A; Kwon, Y-M; Padgett, D E; Hart, A

    2016-02-01

    There are many guidelines that help direct the management of patients with metal-on-metal (MOM) hip arthroplasties. We have undertaken a study to compare the management of patients with MOM hip arthroplasties in different countries. Six international tertiary referral orthopaedic centres were invited to participate by organising a multi-disciplinary team (MDT) meeting, consisting of two or more revision hip arthroplasty surgeons and a musculoskeletal radiologist. A full clinical dataset including history, blood tests and imaging for ten patients was sent to each unit, for discussion and treatment planning. Differences in the interpretation of findings, management decisions and rationale for decisions were compared using quantitative and qualitative methods. Overall agreement between the orthopaedic centres and the recommended treatment plans for the ten patients with MOM hip implants was moderate (kappa = 0.6). Full agreement was seen in a third of cases, however split decisions were also seen in a third of cases. Units differed in their interpretation of the significance of the investigation findings and put varying emphasis on serial changes, in the presence of symptoms. In conclusion, the management of raised or rising blood metal ions, cystic pseudotumours and peri-acetabular osteolysis led to inconsistency in the agreement between centres. Coordinated international guidance and MDT panel discussions are recommended to improve consensus in decision making. A lack of evidence and the subsequent variation in regulator guidance leads to differences in opinions, the clinical impact of which can be reduced through a multi-disciplinary team approach to managing patients with MOM hip implants. Cite this article: Bone Joint J 2016;98-B:179-86. ©2016 The British Editorial Society of Bone & Joint Surgery.

  4. Patient-Reported Outcomes After Revision of Metal-on-Metal Total Bearings in Total Hip Arthroplasty.

    Science.gov (United States)

    Mata-Fink, Ana; Philipson, Daniel J; Keeney, Benjamin J; Ramkumar, Dipak B; Moschetti, Wayne E; Tomek, Ivan M

    2017-04-01

    Failure of metal-on-metal (MOM) total hip arthroplasty (THA) bearings is often accompanied by an aggressive local reaction associated with destruction of bone, muscle, and other soft tissues around the hip. Little is known about whether patient-reported physical and mental function following revision THA in MOM patients is compromised by this soft tissue damage, and whether revision of MOM THA is comparable with revision of hard-on-soft bearings such as metal-on-polyethylene (MOP). We identified 75 first-time MOM THA revisions and compared them with 104 first-time MOP revisions. Using prospective patient-reported measures via the Veterans RAND-12, we compared Physical Component Score and Mental Component Score function at preoperative baseline and postoperative follow-up between revision MOM THA and revision MOP THA. Physical Component Score did not vary between the groups preoperatively and at 1 month, 3 months, and 1 year postoperatively. Mental Component Score preoperatively and 1 and 3 months postoperatively were lower in patients in the MOM cohort compared with patients with MOP revisions (baseline: 43.7 vs 51.3, P MOM THA patients does not differ significantly from the outcomes of revised MOP THA. Mental function is markedly lower in MOM patients at baseline and early in the postoperative period, but does not differ from MOP patients at 1 year after revision. This information should be useful to surgeons and physicians facing MOM THA revision. Copyright © 2016 Elsevier Inc. All rights reserved.

  5. High blood metal ion levels in 19 of 22 patients with metal-on-metal hinge knee replacements.

    Science.gov (United States)

    Laitinen, Minna; Nieminen, Jyrki; Reito, Aleksi; Pakarinen, Toni-Karri; Suomalainen, Piia; Pamilo, Konsta; Parkkinen, Jyrki; Lont, Tonis; Eskelinen, Antti

    2017-06-01

    Background and purpose - There has been increasing alarm regarding metal-on-metal (MoM) joint replacements leading to elevated levels of metal ions and adverse reactions to metal debris (ARMDs). There is little information available concerning the prevalence of and risk factors for these adverse reactions, except with MoM hip joint replacements. We determined the levels of metal ions in blood and the rate of revision due to ARMDs in patients treated with MoM hinge total knee arthroplasty (TKA). Patients and methods - 22 patients with TKAs and MoM hinge connecting mechanisms were studied for whole-blood chromium and cobalt levels at 6 months, 1 year, and/or ≥2 years after surgery. Possible ARMDs were investigated by MRI. 12 patients with TKAs and metal-on-polyethylene (MoP) connecting mechanisms served as controls. Results - The cobalt levels were over 5 ppb in 19 of the 22 patients in the MoM group and in 1 of the 12 patients in the MoP group. The chromium levels were over 5 ppb in 11 of the 22 patients in the MoM group and in none of the 12 patients in the MoP group. Pseudotumors were operated in 4 of the 22 patients in the MoM group and in none of the patients in the MoP group. Interpretation - Our results clearly show that the MoM hinge TKA carries a high risk of increased levels of systemic metal ions and also local ARMD, leading to complicated knee revisions. We therefore discourage the use of MoM hinge TKA.

  6. Few adverse reactions to metal on metal articulation in total hip arthroplasty in a review study on 358 consecutive cases with 1 to 5 years follow-up

    DEFF Research Database (Denmark)

    Stürup, Jens; Dahl, Line; Jensen, Karl Erik

    2012-01-01

    The aim of the present study was to determine the frequency of adverse reaction to metal on metal total hip arthroplasty using a M2a-38 articulation and a Magnum articulation, (Biomet Warsaw, Indiana).All patients who had received a Metal on Metal bearing prosthesis, in two centres in Copenhagen......, were asked to complete a questionnaire about groin pain. Patients with self-reported groin pain, 68/314, underwent a physical examination and had Co and Cr ion levels measured in full blood samples. Fifty patients also had a CT scan performed.The present study found one patient with bilateral...... arthroplasty, who had an adverse reaction on one side. In addition the study showed that females had higher values of Co and Cr, and that younger patient reported groin pain more often.The conclusion of this study is that the number of adverse reactions is low, despite the time of observation being relatively...

  7. Cementless bipolar hemiarthroplasty in femoral neck fractures in elderly

    Directory of Open Access Journals (Sweden)

    SKS Marya

    2011-01-01

    Conclusion: Cementless bipolar hemiarthroplasty for femoral neck fractures in the very elderly permits early return to premorbid life and is not associated with any untoward cardiac event in the perioperative period. It can be considered a treatment option in this select group.

  8. Pseudotumour formation and subsequent resolution in metal-on-metal total hip arthroplasty following revision: Instructional review and an illustrative case report with revision using a dual mobility design.

    Science.gov (United States)

    Sassoon, A A; Barrack, R L

    2016-06-01

    The use of large-diameter metal-on-metal (MoM) components in total hip arthroplasty (THA) is associated with an increased risk of early failure due to adverse local tissue reaction to metal debris (ARMD) in response to the release of metal ions from the bearing couple and/or head-neck taper corrosion. The aim of this paper was to present a review of the incidence and natural history of ARMD and the forms of treatment, with a focus on the need for and extent of resection or debulking of the pseudotumour. An illustrative case report is presented of a patient with an intra-pelvic pseudotumour associated with a large diameter MoM THA, which was treated successfully with revision of the bearing surface to a dual mobility couple and retention of the well-fixed acetabular and femoral components. The pseudotumour was left in situ Resolution of the intra-pelvic mass and normalisation of metal ion levels was observed seven months post-operatively. Cite this article: Bone Joint J 2016;98-B:736-40. ©2016 The British Editorial Society of Bone & Joint Surgery.

  9. Advanced metal artifact reduction MRI of metal-on-metal hip resurfacing arthroplasty implants: compressed sensing acceleration enables the time-neutral use of SEMAC

    Energy Technology Data Exchange (ETDEWEB)

    Fritz, Jan; Thawait, Gaurav K. [Johns Hopkins University School of Medicine, Russell H. Morgan Department of Radiology and Radiological Science, Section of Musculoskeletal Radiology, Baltimore, MD (United States); Fritz, Benjamin [University of Freiburg, Department of Radiology, Freiburg im Breisgau (Germany); Raithel, Esther; Nittka, Mathias [Siemens Healthcare GmbH, Erlangen (Germany); Gilson, Wesley D. [Siemens Healthcare USA, Inc., Baltimore, MD (United States); Mont, Michael A. [Cleveland Clinic Foundation, Department of Orthopedic Surgery, Cleveland, OH (United States)

    2016-10-15

    Compressed sensing (CS) acceleration has been theorized for slice encoding for metal artifact correction (SEMAC), but has not been shown to be feasible. Therefore, we tested the hypothesis that CS-SEMAC is feasible for MRI of metal-on-metal hip resurfacing implants. Following prospective institutional review board approval, 22 subjects with metal-on-metal hip resurfacing implants underwent 1.5 T MRI. We compared CS-SEMAC prototype, high-bandwidth TSE, and SEMAC sequences with acquisition times of 4-5, 4-5 and 10-12 min, respectively. Outcome measures included bone-implant interfaces, image quality, periprosthetic structures, artifact size, and signal- and contrast-to-noise ratios (SNR and CNR). Using Friedman, repeated measures analysis of variances, and Cohen's weighted kappa tests, Bonferroni-corrected p-values of 0.005 and less were considered statistically significant. There was no statistical difference of outcomes measures of SEMAC and CS-SEMAC images. Visibility of implant-bone interfaces and pseudocapsule as well as fat suppression and metal reduction were ''adequate'' to ''good'' on CS-SEMAC and ''non-diagnostic'' to ''adequate'' on high-BW TSE (p < 0.001, respectively). SEMAC and CS-SEMAC showed mild blur and ripple artifacts. The metal artifact size was 63 % larger for high-BW TSE as compared to SEMAC and CS-SEMAC (p < 0.0001, respectively). CNRs were sufficiently high and statistically similar, with the exception of CNR of fluid and muscle and CNR of fluid and tendon, which were higher on intermediate-weighted high-BW TSE (p < 0.005, respectively). Compressed sensing acceleration enables the time-neutral use of SEMAC for MRI of metal-on-metal hip resurfacing implants when compared to high-BW TSE and image quality similar to conventional SEMAC. (orig.)

  10. Comparison of metal ion concentrations and implant survival after total hip arthroplasty with metal-on-metal versus metal-on-polyethylene articulations

    OpenAIRE

    Dahlstrand, Henrik; Stark, André; Wick, Marius C; Anissian, Lucas; Hailer, Nils P; Weiss, Rüdiger J

    2017-01-01

    Background and purpose Large metal-on-metal (MoM) articulations are associated with metal wear and corrosion, leading to increased metal ion concentrations and unacceptable revision rates. There are few comparative studies of 28-mm MoM articulations with conventional metal-on-polyethylene (MoP) couplings. We present a long-term follow-up of a randomized controlled trial comparing MoM versus MoP 28-mm articulations, focused on metal ions and implant survival. Patients and methods 85 patients w...

  11. Usefulness of metal artifact reduction with WARP technique at 1.5 and 3T MRI in imaging metal-on-metal hip resurfacings

    Energy Technology Data Exchange (ETDEWEB)

    Lazik, Andrea; Lauenstein, Thomas C.; Theysohn, Jens M. [University Hospital Essen, Department of Diagnostic and Interventional Radiology and Neuroradiology, Essen (Germany); Landgraeber, Stefan; Schulte, Patrick [University Hospital Essen, Department of Orthopedics, Essen (Germany); Kraff, Oliver [University of Duisburg-Essen, Erwin L. Hahn Institute for Magnetic Resonance Imaging, Essen (Germany)

    2015-03-25

    To evaluate the usefulness of the metal artifact reduction technique ''WARP'' in the assessment of metal-on-metal hip resurfacings at 1.5 and 3T in the context of image quality and imaging speed. Nineteen patients (25 hip resurfacings) were randomized for 1.5 and 3T MRI, both including T1 and T2 turbo spin-echo as well as turbo inversion recovery magnitude sequences with and without view angle tilting and high bandwidth. Additional 3T sequences were acquired with a reduced number of averages and using the parallel acquisition technique for accelerating imaging speed. Artifact size (diameter, area), image quality (5-point scale) and delineation of anatomical structures were compared among the techniques, sequences and field strengths using the Wilcoxon sign-rank and paired t-test with Bonferroni correction. At both field strengths, WARP showed significant superiority over standard sequences regarding image quality, artifact size and delineation of anatomical structures. At 3T, artifacts were larger compared to 1.5T without affecting diagnostic quality, and scanning time could be reduced by up to 64 % without quality degradation. WARP proved useful in imaging metal-on-metal hip resurfacings at 1.5T as well as 3T with better image quality surrounding the implants. At 3T imaging could be considerably accelerated without losing diagnostic quality. (orig.)

  12. The Infection Rate of Metal-on-Metal Total Hip Replacement Is Higher When Compared to Other Bearing Surfaces as Documented by the Australian Orthopaedic Association National Joint Replacement Registry.

    Science.gov (United States)

    Huang, Phil; Lyons, Matt; O'Sullivan, Michael

    2018-02-01

    Despite the well-documented decline in the use of metal-on-metal (MoM) implants over the last decade, there are still controversies regarding whether all MoM implants are created equally. Complications such as elevated serum metal ion levels, aseptic lymphocyte-dominated vasculitis-associated lesion (ALVAL) and pseudotumours have all been well documented, but recent studies suggest increased risk of infection with MoM bearing surfaces. Most of these studies however have small patient numbers. The purpose of this study was to examine the cumulative incidence of revision for infection of MoM bearing surfaces in primary hip arthroplasty at a national and single-surgeon level. Data was collected from the Australian Orthopaedic Association National Joint Replacement Registry, which contains over 98% of all arthroplasties performed in Australia since 2001. The cumulative incidence of revision for infection was extracted at a national level and single-surgeon level. Two hundred seventy-six thousand eight hundred seventy-eight subjects were documented in the Australian registry. The 10-year cumulative percent revision for infection of MoM bearing surfaces in primary total hip replacement (THR) was 2.5% at a national level, compared to 0.8% for other bearing surfaces. The senior author contributed 1755 subjects with 7-year follow-up and a cumulative percent revision for infection of MoM bearing surfaces in primary THR of 36.9%, compared to 2.0% for other bearing surfaces. The cumulative percent of revision of MoM bearing surfaces is higher compared to other bearing surfaces; this is especially pronounced in cumulative percent of revision for infection. There was a higher cumulative percent of revision for infection in MoM bearings surfaces (in particular, large-head MoM) compared to other bearing surfaces at both the national and individual-surgeon level.

  13. Dislocation and spontaneous reduction of the femoral implant against the femoral neck in an infected metal on metal hip resurfacing with complex collection

    Energy Technology Data Exchange (ETDEWEB)

    Tins, Bernhard, E-mail: Bernhard.Tins@rjah.nhs.uk [Department of Radiology, RJAH Orthopaedic Hospital, Oswestry, Shropshire, SY 107 AG (United Kingdom)

    2011-07-15

    Metal on metal resurfacing hip implants are known to have complications unique to this type of implant. The case presented adds a further previously not described complication, the dislocation and spontaneous reduction of the pin of the femoral component against the femoral neck. The radiographic and CT findings are demonstrated. The dislocation was aided by bone loss due to an infection with a large periarticular collection. Periarticular collections in hip resurfacings are often due to a hypersensitivity type reaction to metal debris. However in the case presented it was due to infection. MRI was not able to discern the infection from a sterile collection. CT demonstrated bone loss and periosteal reaction suggestive of infection. In addition calcification of the pseudocapsule was seen, this is not a recognized feature of sterile collections.

  14. Chrome nitride coating reduces wear of small, spherical CrCoMo metal-on-metal articulations in a joint simulator.

    Science.gov (United States)

    Thorkildsen, R; Reigstad, O; Røkkum, M

    2017-03-01

    Metal-on-metal articulations have fallen out of favour in larger joint replacements, but are still used in smaller joints. Coating the articulation has been suggested as one way of reducing wear. We compared a standard 6 mm CrCoMo articulation designed for the carpometacarpal joint of the thumb with a chromium nitride-coated version after 512,000 cycles in a joint simulator. A total of 6 articulations in each group were tested with a unidirectional load of 5 kg in Ringer's solution. We found a statistically significant reduction in weight loss, amount of metallic wear produced and volumetric wear for the chromium nitride-coated articulation. Our findings support the use of chromium nitride coating in order to minimize the amount of metallic wear produced.

  15. Dislocation and spontaneous reduction of the femoral implant against the femoral neck in an infected metal on metal hip resurfacing with complex collection.

    Science.gov (United States)

    Tins, Bernhard

    2011-07-01

    Metal on metal resurfacing hip implants are known to have complications unique to this type of implant. The case presented adds a further previously not described complication, the dislocation and spontaneous reduction of the pin of the femoral component against the femoral neck. The radiographic and CT findings are demonstrated. The dislocation was aided by bone loss due to an infection with a large periarticular collection. Periarticular collections in hip resurfacings are often due to a hypersensitivity type reaction to metal debris. However in the case presented it was due to infection. MRI was not able to discern the infection from a sterile collection. CT demonstrated bone loss and periosteal reaction suggestive of infection. In addition calcification of the pseudocapsule was seen, this is not a recognized feature of sterile collections. Copyright © 2010 Elsevier Ireland Ltd. All rights reserved.

  16. Presence of cobalt and chromium ions in the seminal fluid of young patients with metal-on-metal total hip arthroplasty.

    Science.gov (United States)

    Nikolaou, Vassilios S; Petit, Alain; Zukor, David J; Papanastasiou, Constantine; Huk, Olga L; Antoniou, John

    2013-01-01

    We aimed to investigate the effect of metal ions on the semen of males of child fathering age with metal-on-metal (MM) total hip arthroplasty (THA). Semen was collected form 11 patients with MM THA and 5 control of comparable age. Cobalt and chromium concentrations were measured in both the seminal plasma and in the blood of patients. Results showed that cobalt level was higher in the seminal plasma of MM THA patients (2.89 μg/L) compared to control patients (1.12 μg/L) (P = .011). The ejaculate volume, the sperm density, the total sperm count, the pH, and the percentage of cells with normal morphology were in the range of the World Health Organization criteria for fertile population. Copyright © 2013 Elsevier Inc. All rights reserved.

  17. Toxicology of wear particles of cobalt-chromium alloy metal-on-metal hip implants Part I: physicochemical properties in patient and simulator studies.

    Science.gov (United States)

    Madl, Amy K; Liong, Monty; Kovochich, Michael; Finley, Brent L; Paustenbach, Dennis J; Oberdörster, Günter

    2015-07-01

    The objective of Part I of this analysis was to identify the relevant physicochemical characteristics of wear particles from cobalt-chromium alloy (CoCr) metal-on-metal (MoM) hip implant patients and simulator systems. For well-functioning MoM hip implants, the volumetric wear rate is low (<1mm(3) per million cycles or per year) and the majority of the wear debris is composed of oxidized Cr nanoparticles (<100nm) with minimal or no Co content. For implants with surgical malpositioning, the volumetric wear rate is as high as 100mm(3) per million cycles or per year and the size distribution of wear debris can be skewed to larger sizes (up to 1000nm) and contain higher concentrations of Co. In order to obtain data suitable for a risk assessment of wear debris in MoM hip implant patients, future studies need to focus on particle characteristics relevant to those generated in patients or in properly conducted simulator studies. Metallic implants are very common in the field of orthopedics. Nonetheless, concerns have been raised about the implications of nano-sized particles generated from the wear of these implants. In this two-part review, the authors first attempted to identify and critically evaluate the relevant physicochemical characteristics of CoCr wear particles from hip implant patients and simulator systems. Then they evaluated in vitro and animal toxicology studies with respect to the physicochemistry and dose-relevance to metal-on-metal implant patients. Copyright © 2015 Elsevier Inc. All rights reserved.

  18. Femoral revision with primary cementless stems: a systematic review of the literature.

    Science.gov (United States)

    Cavagnaro, Luca; Formica, Matteo; Basso, Marco; Zanirato, Andrea; Divano, Stefano; Felli, Lamberto

    2017-07-01

    The use of primary cementless stems in femoral revision has gained popularity, but no clear consensus about the correct indication is still present. The aim of our systematic review is to: (1) summarize the available literature focused on the use of cementless primary stem in revision total hip arthroplasty (THA); (2) evaluate whether the use of cementless primary stems could represent a feasible option in hip revision; (3) define the proper indication of this surgical approach. A systematic literature review was performed about the use of cementless primary stems in revision THA. The PRISMA 2009 checklist was considered to edit our review. A total of nine articles were included. The current evidence is primarily Level IV. A total of 439 patients (454 hips) underwent THA revision with primary cementless stem. Partial cementless porous coated stems were used in 246 hips (54.2%). The majority of patients were affected by type I or II Paprosky femoral defects. The mean stem-related survival rate is 95.6% ± 3.8 with a mean follow-up of 4.7 years ± 1.3. Poor standardization of methodological analysis was observed. Current literature shows lacking evidence about primary cementless stems in revision THA. Despite these limitations, we can affirm that primary cementless stems in femoral revision surgery represent a viable option in selected patients. The proper indication is a patient with femoral Paprosky defect types I or II, with low number of previous surgeries and a previous cementless stem.

  19. Cementless bipolar hemiarthroplasty in femoral neck fractures in elderly

    Science.gov (United States)

    Marya, SKS; Thukral, R; Hasan, R; Tripathi, M

    2011-01-01

    Background: Cemented hip arthroplasty is an established treatment for femoral neck fracture in the mobile elderly. Cement pressurization raises intramedullary pressure and may lead to fat embolization, resulting in fatal bone cement implantation syndrome, particularly in patients with multiple comorbidities. The cementless stem technique may reduce this mortality risk but it is technically demanding and needs precise planning and execution. We report the perioperative mortality and morbidity of cementless bipolar hemiarthroplasty in a series of mobile elderly patients (age >70 years) with femoral neck fractures. Materials and Methods: Twenty-nine elderly patients with mean age of 83 years (range:71-102 years) with femoral neck fractures (23 neck of femur and 6 intertrochanteric) were operated over a 2-year period (Nov 2005–Oct 2007). All were treated with cementless bipolar hemiarthroplasty. Clinical and radiological follow-up was done at 3 months, 6 months, 12 months, and then yearly. Results: The average follow-up was 36 months (range 26-49 months). The average duration of surgery and blood loss was 28 min from skin to skin (range, 20–50 min) and 260 ml (range, 95–535 ml), respectively. Average blood transfusion was 1.4 units (range, 0 to 4 units) Mean duration of hospital stay was 11.9 days (7–26 days). We had no perioperative mortality or serious morbidity. We lost two patients to follow-up after 12 months, while three others died due to medical conditions (10–16 months post surgery). Twenty-four patients were followed to final follow-up (average 36 months; range: 26–49 months). All were ambulatory and had painless hips; the mean Harris hip score was 85 (range: 69–96). Conclusion: Cementless bipolar hemiarthroplasty for femoral neck fractures in the very elderly permits early return to premorbid life and is not associated with any untoward cardiac event in the perioperative period. It can be considered a treatment option in this select group. PMID

  20. Regional bone loss following femoral neck fracture: A comparison between cemented and cementless hemiarthroplasty.

    Science.gov (United States)

    Vidović, Dinko; Punda, Marija; Daraboš, Nikica; Bekavac-Bešlin, Miroslav; Bakota, Bore; Matejčić, Aljoša

    2015-11-01

    The aim of this prospective, randomised study was to measure and evaluate regional bone mineral changes and clinical results following the use of cemented and cementless hemiarthroplasty (HA) for treatment of femoral neck fracture in elderly patients. The study comprised 60 patients, 30 with cemented HA (group A) and 30 with cementless HA (group B). All patients underwent osteodensitometry of the contralateral hip, lumbar spine and bilateral distal femur. Dual-energy x-ray absorptiometry (DEXA) was scheduled at 1 month, 6 months and 1 year after surgery. Harris Hip Score (HHS) was used for functional assessment. Overall mortality rate was 20.3% within 1 year after surgery. There were no significant differences in morbidity, mortality and hospital stay between the two groups of patients. The implantation of cemented prosthesis took statistically significantly longer than that of cementless prosthesis (79.03±3.59 vs 68.02±5.97min; p=0.00). Functional score in patients treated with cemented HA was significantly higher compared with those with cementless HA. There was a trend of less intensive reduction of bone mineral density (BMD) in regions of interest of the lumbar spine and ipsilateral distal femur in patients with cemented HA (group A), whereas bone loss was less pronounced for the contralateral hip and distal femur in patients treated with cementless HA (group B). Management of displaced femoral neck fractures in elderly patients with cemented and cementless HA provides a comparable outcome with regard to morbidity and mortality; however, functional outcome of patients treated with cementless HA tends to be lower. There is less intensive BMD reduction in lumbar spine and ipsilateral distal femur in patients treated with cemented HA, whereas BMD reduction in patients treated with cementless HA is more likely to be less intensive in contralateral hip and distal femur. Copyright © 2015 Elsevier Ltd. All rights reserved.

  1. Metal-on-metal bearings in total hip arthroplasties: Influence of cobalt and chromium ions on bacterial growth and biofilm formation.

    Science.gov (United States)

    Hosman, Anton H; van der Mei, Henny C; Bulstra, Sjoerd K; Busscher, Henk J; Neut, Daniëlle

    2009-03-01

    Metal-on-metal (MOM) bearings involving cobalt-chromium (Co-Cr) alloys in total hip arthroplasties are becoming more and more popular due to their low wear. Consequences of corrosion products of Co-Cr alloys are for the most part unclear, and the influence of cobalt and chromium ions on biofilm formation has never been studied. Therefore, the aim of this study was to evaluate how Co-Cr ions affect bacterial growth, biofilm formation, and architecture. A collection of clinically isolated and commercially available bacterial strains were exposed to Co-Cr concentrations as found in serum and above as found in adjacent tissue. Planktonic growth of bacteria was inhibited by concentrations of 200,000/93,000 microg/L Co-Cr. Co-Cr concentrations up to 20/9.3 microg/L as reported to occur in serum revealed no consistent influence on biofilm formation, but higher concentrations of 200,000/93,000 microg/L significantly reduced Staphylococcus aureus and CNS biofilm formation. As indicated by confocal laser scanning microscopy, no dead bacteria were encountered in the biofilms, and the metal ion concentrations used must be classified as growth-inhibiting and not bactericidal. Long-term clinical data on infection rates for Co-Cr MOM-bearings are not yet available, but the current results suggest that Co-Cr ions may yield these prostheses less prone to biofilm formation and subsequent infection. (c) 2008 Wiley Periodicals, Inc.

  2. Asymptomatic prospective and retrospective cohorts with metal-on-metal hip arthroplasty indicate acquired lymphocyte reactivity varies with metal ion levels on a group basis

    Science.gov (United States)

    Hallab, NJ; Caicedo, M; McAllister, K; Skipor, A; Amstutz, H; Jacobs, JJ

    2012-01-01

    Some tissues from metal-on-metal (MoM) hip arthroplasty revisions have shown evidence of adaptive-immune reactivity (i.e., excessive peri-implant lymphocyte infiltration/activation). We hypothesized that, prior to symptoms, some people with MoM hip arthroplasty will develop quantifiable metal-induced lymphocyte reactivity responses related to peripheral metal ion levels. We tested 3 cohorts (Group-1: n=21 prospective longitudinal MoM hip arthroplasty; Group-2: n=17 retrospective MoM hip arthroplasty; and Group-3: n=20 controls without implants). We compared implant position, metal-ion release, and immuno-reactivity. MoM cohorts had elevated (p2), compared with 76% of Group-2 and 15% of Group-3 controls (patch testing was a poor diagnostic indicator with only 1/21 Group-1 positive). Higher cup-abduction angles (50° vs. 40°) in Group-1 were associated with higher serum Cr (p<0.07). However, sub-optimal cup-anteversion angles (9° vs. 20°) had higher serum Co (p<0.08). Serum Cr and Co were significantly elevated in reactive vs. non-reactive Group-1 participants (p<0.04). CD4+CD69+ T-helper lymphocytes (but not CD8+) and IL-1β, IL-12 and IL-6 cytokines were all significantly elevated in metal-reactive vs. non-reactive Group-1 participants. Our results showed that lymphocyte reactivity to metals can develop within the first 1 to 4 years after MoM arthroplasty in asymptomatic patients and lags increases in metal ion levels. This increased metal reactivity was more prevalent in those individuals with extreme cup angles and higher amounts of circulating metal. PMID:22941579

  3. Effects of chronic cobalt and chromium exposure after metal-on-metal hip resurfacing: An epigenome-wide association pilot study.

    Science.gov (United States)

    Steinberg, Julia; Shah, Karan M; Gartland, Alison; Zeggini, Eleftheria; Wilkinson, Jeremy Mark

    2017-10-01

    Metal-on-metal (MOM) hip resurfacing has recently been a popular prosthesis choice for the treatment of symptomatic arthritis, but results in the release of cobalt and chromium ions into the circulation that can be associated with adverse clinical effects. The mechanism underlying these effects remains unclear. While chromosomal aneuploidy and translocations are associated with this exposure, the presence of subtle structural epigenetic modifications in patients with MOM joint replacements remains unexplored. Consequently, we analyzed whole blood DNA methylation in 34 OA patients with MOM hip resurfacing (MOM HR) compared to 34 OA patients with non-MOM total hip replacements (non-MOM THR), using the genome-wide Illumina HumanMethylation 450k BeadChip. No probes showed differential methylation significant at 5% false-discovery rate (FDR). We also tested association of probe methylation levels with blood chromium and cobalt levels directly; there were no significant associations at 5% FDR. Finally, we used the "epigenetic clock" to compare estimated to actual age at sample for all individuals. We found no significant difference between MOM HR and non-MOM THR, and no correlation of age acceleration with blood metal levels. Our results suggest the absence of large methylation differences systemically following metal exposure, however, larger sample sizes will be required to identify potential small effects. Any DNA methylation changes that may occur in the local periprosthetic tissues remain to be elucidated. © 2017 The Authors. Orthopaedic Research Society. Published by Wiley Periodicals, Inc. on behalf of Orthopaedic Research Society. J Orthop Res 35:2323-2328, 2017. © 2017 The Authors. Orthopaedic Research Society. Published by Wiley Periodicals, Inc.

  4. Metal ion concentrations and semen quality in patients undergoing hip arthroplasty: A prospective comparison between metal-on-metal and metal-on-polyethylene implants.

    Science.gov (United States)

    Chen, Szu-Yuan; Chang, Chih-Hsiang; Hu, Chih-Chien; Chen, Chun-Chieh; Chang, Yu-Han; Hsieh, Pang-Hsin

    2016-03-01

    The widespread usage of metal-on-metal (MoM) articulations in total hip arthroplasty (THA) has been tempered by concerns of increased metal ion production. The purpose of the study is to evaluate the influence of metal ion exposure on semen quality in young male patients undergoing THA. Male patients who were scheduled for unilateral THA and aged between 20 and 45 years were prospectively enrolled. Patients were sorted into MoM and metal-on-polyethylene (MoP) groups with equal case number. Semen and blood metal ion levels were measured and sperm analysis was performed before, 6 months after, and 1 year after surgery. Compared to preoperative baseline, patients (n = 50) in both groups had increased cobalt (Co) and chromium (Cr) concentrations in blood and seminal fluid after surgery. Between-group comparisons at 6 months and 1 year after surgery showed that patients in the MoM group both had a greater Co concentration in blood and semen and a greater Cr concentration in blood and semen. Patients receiving MoM prosthesis had a reduced percentage of morphologically normal sperm, and decreases from the preoperative level (44.7%) were significant at 6 months (36.8%, p = 0.03) and 1 year (33.8%, p = 0.004). Our data shows a significantly greater concentration of metal ion in blood and semen in patients with MoM prosthesis with a reduced percentage of morphologically normal sperm. Despite small effects on sperm quality, some concerns remain. Further studies are necessary to determine sources of metal ion and to investigate effects on male fertility. © 2015 Orthopaedic Research Society. Published by Wiley Periodicals, Inc.

  5. In vitro stability of cemented and cementless femoral stems with compaction.

    Science.gov (United States)

    Chareancholvanich, Keerati; Bourgeault, Craig A; Schmidt, Andrew H; Gustilo, Ramon B; Lew, William D

    2002-01-01

    Rigidity of initial fixation is a key factor contributing to the longevity of cemented and cementless femoral components in total hip arthroplasty. The objective of this study was to measure the initial stability of primary cemented and cementless femoral components under load when 15 pairs of cadaveric femurs were prepared by outward compaction of femoral cancellous bone in situ or by conventional extraction broaching. Three-dimensional micromotion was measured at proximal and distal locations on the femoral components using a device with spherical targets and linear variable differential transformers. External loads simulating the stance phases of level walking and stair ascent were applied to the femoral components by a materials test machine. Bone preparation method significantly affected each of the translation and rotation components of micromotion with cemented and cementless fixation. Micromotion with broaching was consistently greater than with compaction. Compared with compaction, the magnitude of the micromotion translation vector for broaching was an average of 3.9 (standard deviation, 3.1) times greater with cemented fixation, and an average of 2.3 (standard deviation, 1.4) times greater with cementless fixation. The results of this study showed the effectiveness of compaction of femoral cancellous bone in improving the initial stability of cemented and cementless femoral components in primary total hip arthroplasty.

  6. Initial mechanical stability of cementless highly-porous titanium tibial components

    Energy Technology Data Exchange (ETDEWEB)

    Stone, Timothy Brandon [Los Alamos National Laboratory; Amer, Luke D [Los Alamos National Laboratory; Warren, Christopher P [Los Alamos National Laboratory; Cornwell, Phillip [Los Alamos National Laboratory; Meneghini, R Michael [UNIV OF CONNECTICUT HEALTH CENTER

    2008-01-01

    Cementless fixation in total knee replacement has seen limited use since reports of early failure surfaced in the late 80s and early 90s. However the emergence of improved biomaterials, particularly porous titanium and tantalum, has led to a renewed interest in developing a cementless tibial component to enhance long-term survivorship of the implants. Cement is commonly employed to minimize micromotion in new implants but represents a weak interface between the implant and bone. The elimination of cement and application of these new biomaterials, which theoretically provide improved stability and ultimate osseointegration, would likely result in greater knee replacement success. Additionally, the removal of cement from the procedure would help minimize surgical durations and get rid of the time needed for curing, thereby the chance of infection. The purpose of this biomechanical study was twofold. The first goal was to assess whether vibration analysis techniques can be used to evaluate and characterize initial mechanical stability of cementless implants more accurately than the traditional method of micromotion determination, which employs linear variable differential transducers (LVDTs). Second, an evaluative study was performed to determine the comparative mechanical stability of five designs of cementless tibial components under mechanical loading designed to simulate in vivo forces. The test groups will include a cemented Triathlon Keeled baseplate control group, three different 2-peg cementless baseplates with smooth, mid, and high roughnesses and a 4-peg cement/ess baseplate with mid-roughness.

  7. Periprosthetic fracture in the elderly with anatomic modular cementless hemiarthroplasty.

    Science.gov (United States)

    Kouyoumdjian, P; Dhenin, A; Dupeyron, A; Coulomb, R; Asencio, G

    2016-10-01

    The use of an anatomic cementless stem in hemiarthroplasties for femoral intracapsular proximal fracture has been debated, notably because of bone weakness and/or morphological defects related to osteoporosis. We therefore conducted a retrospective study in subjects over 75 years of age who had received an anatomic stem partially coated with hydroxyapatite. The objectives were to determine: 1) the incidence of periprosthetic fractures (PPFs) and, 2) the influence of anatomic factors, including the Cortical Bone Ratio (CBR) (the relation between the endosteal and external diameter of the femoral diaphysis 10cm below the lesser trochanter). The risk of PPF with an anatomic cementless implant is greater than with cemented stems. We retrospectively analyzed 233 patients followed up for 5 years after their surgery. The stem used was an anatomic stem with a modular neck partially coated with hydroxyapatite. The risk factors examined were age, gender, history of osteoporotic fractures, diverse causes of secondary osteoporosis, and proximal bone stock according to various referenced radiological indices such as the CBR. Twenty patients (15%) were lost to follow-up, 74 had died (32%) but did not undergo revision for PPF, 15 of the 139 survivors at the last follow-up (10.8%) had had a PPF, five (3.6%; four females, one male) were early fractures (≤2 months after implantation), ten (7.2%; two females, eight males) were late fractures (>2 months). Male gender was protective for PPF occurrence (RR=0.129; 95%CI (0.04-0.39); P=0.0003), whereas secondary factors of osteoporosis (RR=2.035; 95%CI (1.11-3.72); P=0.0211), and CBR>0.49 (RR=227.42; 95%CI (1.072-48,226.76); P=0.0471) were found as risk factors of PPF. The PPF rate was greater than that related to cemented stems, requiring that morphological and clinical factors of bone weakness (collected with the patient history and related to osteoporosis) be taken into account. A CBR>0.49 requires caution on the use of this type

  8. Comparison of metal ion concentrations and implant survival after total hip arthroplasty with metal-on-metal versus metal-on-polyethylene articulations.

    Science.gov (United States)

    Dahlstrand, Henrik; Stark, André; Wick, Marius C; Anissian, Lucas; Hailer, Nils P; Weiss, Rüdiger J

    2017-10-01

    Background and purpose - Large metal-on-metal (MoM) articulations are associated with metal wear and corrosion, leading to increased metal ion concentrations and unacceptable revision rates. There are few comparative studies of 28-mm MoM articulations with conventional metal-on-polyethylene (MoP) couplings. We present a long-term follow-up of a randomized controlled trial comparing MoM versus MoP 28-mm articulations, focused on metal ions and implant survival. Patients and methods - 85 patients with a mean age of 65 years at surgery were randomized to a MoM (Metasul) or a MoP (Protasul) bearing. After 16 years, 38 patients had died and 4 had undergone revision surgery. 13 patients were unavailable for clinical follow-up, leaving 30 patients (n = 14 MoM and n = 16 MoP) for analysis of metal ion concentrations and clinical outcome. Results - 15-year implant survival was similar in both groups (MoM 96% [95% CI 88-100] versus MoP 97% [95% CI 91-100]). The mean serum cobalt concentration was 4-fold higher in the MoM (1.5 μg/L) compared with the MoP cohort (0.4 μg/L, p MoM (2.2 μg/L) compared with the MoP cohort (1.0 μg/L, p = 0.05). Mean creatinine levels were similar in both groups (MoM 93 μmol/L versus MoP 92 μmol/L). Harris hip scores differed only marginally between the MoM and MoP cohorts. Interpretation - This is the longest follow-up of a randomized trial on 28-mm MoM articulations, and although implant survival in the 2 groups was similar, metal ion concentrations remained elevated in the MoM cohort even in the long term.

  9. Risk factors for failure of the 36 mm metal-on-metal Pinnacle total hip arthroplasty system: a retrospective single-centre cohort study.

    Science.gov (United States)

    Matharu, G S; Nandra, R S; Berryman, F; Judge, A; Pynsent, P B; Dunlop, D J

    2017-05-01

    To determine ten-year failure rates following 36 mm metal-on-metal (MoM) Pinnacle total hip arthroplasty (THA), and identify predictors of failure. We retrospectively assessed a single-centre cohort of 569 primary 36 mm MoM Pinnacle THAs (all Corail stems) followed up since 2012 according to Medicines and Healthcare Products Regulation Agency recommendations. All-cause failure rates (all-cause revision, and non-revised cross-sectional imaging failures) were calculated, with predictors for failure identified using multivariable Cox regression. Failure occurred in 97 hips (17.0%). The ten-year cumulative failure rate was 27.1% (95% confidence interval (CI) 21.6 to 33.7). Primary implantation from 2006 onwards (hazard ratio (HR) 4.30; 95% CI 1.82 to 10.1; p = 0.001) and bilateral MoM hip arthroplasty (HR 1.59; 95% CI 1.03 to 2.46; p = 0.037) predicted failure. The effect of implantation year on failure varied over time. From four years onwards following surgery, hips implanted since 2006 had significantly higher failure rates (eight years 28.3%; 95% CI 23.1 to 34.5) compared with hips implanted before 2006 (eight years 6.3%; 95% CI 2.4 to 15.8) (HR 15.2; 95% CI 2.11 to 110.4; p = 0.007). We observed that 36 mm MoM Pinnacle THAs have an unacceptably high ten-year failure rate, especially if implanted from 2006 onwards or in bilateral MoM hip patients. Our findings regarding implantation year and failure support recent concerns about the device manufacturing process. We recommend all patients undergoing implantation since 2006 and those with bilateral MoM hips undergo regular investigation, regardless of symptoms. Cite this article: Bone Joint J 2017;99-B:592-600. ©2017 Matharu et al.

  10. Sports Activity Following Cementless Metaphyseal Hip Joint Arthroplasty.

    Science.gov (United States)

    Czech, Szymon; Hermanson, Jacek; Rodak, Piotr; Stołtny, Tomasz; Rodak, Łukasz; Kasperczyk, Sławomir; Koczy, Bogdan; Mielnik, Michał

    2017-12-01

    An adequate level of physical activity has a substantial effect on both mental and physical human health. Physical activity is largely dependent on the function of the musculoskeletal and articular system. One of the most frequent diseases of this system is degenerative joint disease. Due to the changing and more demanding lifestyles and patients' willingness to be involved in sports activity, the expectations of hip joint arthroplasty are becoming increasingly high. Alleviating pain ceases to be the only reason for which patients choose surgical interventions, while the expectations often include involvement in various sports. Only few studies contain recommendations concerning the frequency, type and intensity of sports activity which are acceptable after hip joint arthroplasty. The aim of the study was to evaluate function and physical activity of people following cementless short-stem hip joint arthroplasty in the observation of at least five years. The study group comprised 106 patients who underwent total hip arthroplasty due to degenerative joint diseases, chosen according to inclusion criteria. Patients underwent routine physical examinations following the Harris Hip Score protocol, responded to the UCLA scale and questionnaires concerning pre-surgical and current physical activity. Our results demonstrated that hip joint arthroplasty in people suffering from degenerative joint diseases has a beneficial effect on their level of functioning and physical activity. Although physical activity and the level of functioning obviously reduced as a person aged, the level of physical activity continued to be very high in both groups, with function of the hip joint evaluated as very good.

  11. A biodegradable gentamicin-hydroxyapatite-coating for infection prophylaxis in cementless hip prostheses

    NARCIS (Netherlands)

    Neut, D.; Dijkstra, R. J. B.; Thompson, J. I.; Kavanagh, C.; van der Mei, H. C.; Busscher, H. J.

    2015-01-01

    A degradable, poly (lactic-co-glycolic acid) (PLGA), gentamicin-loaded prophylactic coating for hydroxyapatite (HA)-coated cementless hip prostheses is developed with similar antibacterial efficacy as offered by gentamicin-loaded cements for fixing traditional, cemented prostheses in bone. We

  12. The cementless AGC 2000 knee prosthesis: 20-year results in a consecutive series

    DEFF Research Database (Denmark)

    Eriksen, Jamila; Christensen, Jan; Solgaard, Søren

    2009-01-01

    One hundred and fourteen AGC 2000 porous-coated cementless total knee arthroplasties were performed in 102 patients between 1984 and 1986. We report their 20-year results with patient assessment, Hospital for Special Surgery knee score, weight-bearing radiographs done under fluoroscopic control a...

  13. Still no single gold standard for using cementless femoral stems routinely in total hip arthroplasty

    Directory of Open Access Journals (Sweden)

    Joseph T. Moskal, MD

    2016-12-01

    Conclusions: Using evidence-based data should be better guidance in selecting the most reliable implants for THA. Although cementless femoral fixation for THA has evolved to the “new standard,” it has not been proven to be the “gold standard” for all patients.

  14. Sports Activity Following Cementless Metaphyseal Hip Joint Arthroplasty

    Directory of Open Access Journals (Sweden)

    Czech Szymon

    2017-12-01

    Full Text Available An adequate level of physical activity has a substantial effect on both mental and physical human health. Physical activity is largely dependent on the function of the musculoskeletal and articular system. One of the most frequent diseases of this system is degenerative joint disease. Due to the changing and more demanding lifestyles and patients’ willingness to be involved in sports activity, the expectations of hip joint arthroplasty are becoming increasingly high. Alleviating pain ceases to be the only reason for which patients choose surgical interventions, while the expectations often include involvement in various sports. Only few studies contain recommendations concerning the frequency, type and intensity of sports activity which are acceptable after hip joint arthroplasty. The aim of the study was to evaluate function and physical activity of people following cementless short-stem hip joint arthroplasty in the observation of at least five years. The study group comprised 106 patients who underwent total hip arthroplasty due to degenerative joint diseases, chosen according to inclusion criteria. Patients underwent routine physical examinations following the Harris Hip Score protocol, responded to the UCLA scale and questionnaires concerning pre-surgical and current physical activity. Our results demonstrated that hip joint arthroplasty in people suffering from degenerative joint diseases has a beneficial effect on their level of functioning and physical activity. Although physical activity and the level of functioning obviously reduced as a person aged, the level of physical activity continued to be very high in both groups, with function of the hip joint evaluated as very good.

  15. No Difference in Reoperations at 2 Years Between Ceramic-on-metal and Metal-on-metal THA: A Randomized Trial.

    Science.gov (United States)

    Engh, C Anderson; Sritulanondha, Supatra; Korczak, Abigail; Whalen, Terrence David; Naudie, Douglas D R; McCalden, Richard W; MacDonald, Steven J

    2016-02-01

    Hard-on-hard bearings for total hip arthroplasty continue to warrant analysis even though crosslinked polyethylene is performing very well. Ceramic-on-metal (CoM) has low in vitro wear and did well in an early clinical trial. We report on a prospective, randomized, multicenter investigational device trial comparing CoM with metal-on-metal (MoM). (1) Is there a difference in the number or type of revisions comparing CoM with MoM? (2) Are cobalt and chromium metal levels different for CoM and MoM THA? Between August 2005 and October 2006, of 1015 patients screened, 390 patients were enrolled at 11 centers and randomized to 194 CoM and 196 MoM bearings. There was no difference in the preoperative patient demographics between the study groups. Mean followup was 50 months (range, 22-75 months). Seventy-two patients from two centers had metal level analysis. With the numbers available, there was no difference in the proportion of patients undergoing revisions between the MoM and the CoM cohorts (MOM: 3% [six of 196]; COM: 1.5% [three of 194]; p = 0.50). Four MoM revisions were unrelated to the bearing surface. Two had bearing surface-related reoperations, one for an aseptic lymphocyte-dominated vasculitis-associated lesion and one for elevated metal levels with acetabular malposition. None of the CoM revisions were related to the bearing surface. The metal level analysis revealed that in contrast to the CoM, the MoM bearing group had increasing values of erythrocyte and serum cobalt from 1 to 5 years (CoM erythrocyte 0.45-0.55 ppb, p = 0.11 and CoM serum 0.88-0.85, p = 0.55, and MoM erythrocyte 0.32-0.51 ppb, p MoM serum 0.65-1.01 ppb, p MoM cobalt levels in erythrocytes and serum at 5 years were more variable than at 1 year (erythrocyte interquartile range [IQR], 0.26-0.44 to 0.31-1.21 ppb and serum IQR, 0.42-0.80 to 0.64-2.20 ppb, p MoM cobalt elevations may be important considering recent reports of taper corrosion. This CoM bearing was approved by the FDA but

  16. Implications of Introducing New Technology: Comparative Survivorship Modeling of Metal-on-Metal Hip Replacements and Contemporary Alternatives in the National Joint Registry.

    Science.gov (United States)

    Hunt, Linda P; Whitehouse, Michael R; Beswick, Andrew; Porter, Martyn L; Howard, Peter; Blom, Ashley W

    2018-02-07

    New medical technologies are often used widely without adequate supporting data, a practice that can lead to widespread catastrophic failure such as occurred with metal-on-metal (MoM) hip replacements. We determined both how revision rates would have differed if, instead of receiving MoM hip replacements, patients had received existing alternatives and the subsequent cumulative re-revision rates of the patients who did receive MoM hip replacements compared with alternatives. This study is a population-based longitudinal cohort study of patient data recorded in the National Joint Registry (NJR) for England, Wales and Northern Ireland between April 2003 and December 2014. We ascertained implant failure rates separately among stemmed MoM total hip replacement (THR) and hip-resurfacing procedures and, using flexible parametric survival modeling, compared them with the failure rates that would have been expected had existing alternatives been used. We used Kaplan-Meier survivorship analysis to compare cumulative re-revision of patients who received stemmed MoM primary replacements that failed and of those who underwent hip resurfacing that failed with those whose non-MoM THRs had failed. In all, 37,555 patients underwent MoM hip resurfacing, with a 10-year revision rate of 12.6% (95% confidence interval [CI]: 12.2% to 13.1%) compared with a predicted revision rate of 4.8% if alternative implants had been used. The 32,024 stemmed MoM THRs had a 19.8% (95% CI: 18.9% to 20.8%) 10-year failure rate compared with an expected rate of 3.9% if alternatives had been used. For every 100 MoM hip-resurfacing procedures, there were 7.8 excess revisions by 10 years, and for every 100 stemmed MoM THR procedures, there were 15.9, which equates to 8,021 excess first revisions. Seven-year re-revision rates were 14.9% (95% CI: 13.8% to 16.2%) for stemmed non-MoM THRs, 18.0% (95% CI: 15.7% to 20.7%) for MoM hip resurfacing, and 19.8% (95% CI: 17.0% to 23.0%) for stemmed MoM THRs. This

  17. Cementless total hip arthroplasty for patients previously treated with femoral osteotomy for hip dysplasia: the incidence of periprosthetic fracture

    National Research Council Canada - National Science Library

    Ohishi, Masanobu; Nakashima, Yasuharu; Yamamoto, Takuaki; Motomura, Goro; Fukushi, Jun-ichi; Hamai, Satoshi; Kohno, Yusuke; Iwamoto, Yukihide

    2016-01-01

    Femur deformities can make stem fixation difficult in total hip arthroplasty (THA). We report the clinical results of cementless THA using a press-fit stem in patients who had previously undergone femoral osteotomy for hip...

  18. No difference between cemented and cementless total knee arthroplasty in young patients: a review of the evidence.

    Science.gov (United States)

    Franceschetti, Edoardo; Torre, Guglielmo; Palumbo, Alessio; Papalia, Rocco; Karlsson, Jón; Ayeni, Olufemi R; Samuelsson, Kristian; Franceschi, Francesco

    2017-06-01

    The present piece of work provides improved knowledge about the evidence related to TKA in patients 60 years of age or younger, with special focus on fixation methods. Main concern of the review is to analyse the difference of survival rate and complications of cemented and cementless implants. An electronic search was carried out between October and December 2015, through CINAHL, PubMed and the Cochrane Central Registry of Controlled Trials web databases. Articles in English, Italian, French and Spanish were considered for inclusion. Only peer-reviewed studies with adult patients aged 60 years or less, with diagnosis of osteoarthritis in more than 90% of the subjects, were considered for inclusion. All studies had to report outcomes after TKA with either cemented or cementless fixation technique. No significant differences in terms of clinical, functional and radiological outcomes were found between cemented and cementless implants. Good clinical and functional results were obtained in terms of the Knee Society score and Western Ontario and McMaster Universities Osteoarthritis Index for both techniques. Radiographic results showed that radiolucent lines of <2 mm in width were detected at radiographs, without difference between cemented or cementless implants. Well-conducted trials on cemented versus cementless TKA were carried out in few papers. A survival rate of over 90% was reported in the majority of the studies at a mean follow-up of 8.6 years (range 5-18 years). Similar results were observed in terms of functional outcome and survival rates for both cemented and cementless TKAs. High survival rates were reported for both operative techniques and cemented TKA did not offer additional benefit. Assuming that cementless prosthesis allows a stable fixation and reduces the time of operation, the authors recommend the cementless fixation as a primary choice in the investigated patient population. However, evidence is low, and further research is needed. IV.

  19. Early rehabilitation in Resurfacing, standard and large head THA patients

    DEFF Research Database (Denmark)

    Penny, Jeannette Østergaard; Varmarken, Jens-Erik; Ovesen, Ole

    2009-01-01

      Introduction For patients in employment a fast rehabilitation is important. The reduced risk of dislocation when using a large-head metal-on-metal articulation theoretically offers a faster rehabilitation than a THA with a 28 mm articulation due to no restrictions. The larger surgical incision...... in the resurfacing patient may impair the early rehabilitation. We aimed to investigate early differences in rehabilitation parameters amongst the different groups. Materials and methods We randomized to resurfacing (n=20), standard 28 mm THA (n=19) and large head MoM THA (n=12). We recorded operation time, blood...

  20. Is increased modularity associated with increased fretting and corrosion damage in metal-on-metal total hip arthroplasty devices?: a retrieval study.

    Science.gov (United States)

    Higgs, Genymphas B; Hanzlik, Josa A; MacDonald, Daniel W; Gilbert, Jeremy L; Rimnac, Clare M; Kurtz, Steven M

    2013-09-01

    This retrieval study documents taper damage at modular interfaces in retrieved MOM THA systems and investigates if increased modularity is associated with increased fretting and corrosion. One hundred thirty-four (134) heads and 60 stems (41 modular necks) of 8 different bearing designs (5 manufacturers) were analyzed. Damage at the shell-liner interface of 18 modular CoCr acetabular liners and the corresponding 11 acetabular shells was also evaluated. The results of this study support the hypothesis that fretting and corrosion damage occurs at a variety of modular component interfaces in contemporary MOM THAs. We also found that modularity of the femoral stem was associated with increased damage at the head. An analysis of component and patient variables revealed that dissimilar alloy pairing, larger head sizes, increased medio-lateral offsets and longer neck moment arms were all associated with increased taper damage at the modular interfaces. © 2013.

  1. One-stage revision of an infected cementless total hip replacement.

    Science.gov (United States)

    Ficklin, Michael G; Kowaleski, Michael P; Kunkel, Kevin A R; Suber, Jonathan T

    2016-11-23

    A two-year-old, 44 kg dog with a right Helica cementless total hip replacement (THR) was radiographically diagnosed with implant loosening eight months after the index total hip replacement procedure. Subsequent synoviocentesis and synovial fluid culture revealed a methicillin-resistant coagulase-negative Staphylococcus spp infection of the right THR. A one-stage revision using a hybrid BFX cementless acetabular cup and CFX cemented femoral stem was performed. Vancomycin and micro-silver antimicrobial powder impregnated cement were used in the revision. At re-evaluation 27 months following the revision procedure, the patient did not exhibit any signs of lameness. Radiographic images confirmed stable implants, with bone ingrowth into the cup and no signs of implant loosening. Our report demonstrates the success of a one-stage THR revision when faced with a multi-drug resistant periprosthetic infection, when combined with the use of micro-silver antimicrobial powder and culture-based antibiotic impregnated cement therapy.

  2. Cemented, cementless, and hybrid prostheses for total hip replacement: cost effectiveness analysis

    OpenAIRE

    Pennington, Mark; Grieve, Richard; Sekhon, Jasjeet S; Gregg, Paul; Black, Nick; van der Meulen, Jan H

    2013-01-01

    OBJECTIVE To compare the cost effectiveness of the three most commonly chosen types of prosthesis for total hip replacement. DESIGN Lifetime cost effectiveness model with parameters estimated from individual patient data obtained from three large national databases. SETTING English National Health Service. PARTICIPANTS Adults aged 55 to 84 undergoing primary total hip replacement for osteoarthritis. INTERVENTIONS Total hip replacement using either cemented, cementless, or hybrid prostheses. M...

  3. Cementless Hip Arthroplasty in Southern Iran, Midterm Outcome and Comparison of Two Designs

    Directory of Open Access Journals (Sweden)

    Gholam Hossein Shahcheraghi

    2015-09-01

    Full Text Available Background: Cementless hip prosthesis was designed to provide biologic fixation, without the use of cement. The second generation components have shown more reliable bone ingrowths and survival rates. We are reporting a midterm result of two designs of cementless prosthesis in a unique culture with different social habits and expectations. Methods: 52 primary cementless total hip arthroplasty in 42 patients with the mean age of 48.8 years were retrospectively studied. Two groups of prosthesis had been implanted: Harris-Galante II (HGII in 15 and Versys-Trilogy (V-T in 37 hips, both from Zimmer company. The patients were assessed clinically, radiographically and with Harris hip score, SF36, WOMAC, and MACTAR questionnaires, with 65 months (26-136 mean follow-up. Results: All the V-T prostheses had survived well. Eight of HG II were revised by the last follow-up in 19-102 months. All had undergone acetabular revision and 2 combined with femoral revision. Broken tines of HGII cups were seen in 4 radiographs. The 65 months overall survival was 96.2% for femoral and 84.6% for acetabular components. 90% had good or excellent Harris hip scores. The functional scores were poorer in the HG II group. Pain relief and improved walking were the two main patients’ expectations fulfilled in 97.6% and 92.8%, respectively. Conclusions: The outcome of cementless total hip arthroplasty (THA is satisfactory and comparable with the literature based on the results of function and survival of this small comparative group. The use of HGII acetabular component should be abandoned.

  4. Cementless Oxford medial unicompartimental knee replacement: an independent series with a 5-year-follow-up.

    Science.gov (United States)

    Panzram, Benjamin; Bertlich, Ines; Reiner, Tobias; Walker, Tilman; Hagmann, Sébastien; Gotterbarm, Tobias

    2017-07-01

    Cemented unicompartmental knee replacement (UKR) has proven excellent long-term survival rates and functional scores in Price et al. (Clin Orthop Relat Res 435:171-180, 2005), Price and Svard (Clin Orthop Relat Res 469(1):174-179, 2011) and Murray et al. (Bone Joint Surg Br 80(6):983-989, 1998). The main causes for revision, aseptic loosening and pain of unknown origin might be addressed by cementless UKR in Liddle et al. (Bone Joint J 95-B(2):181-187, 2013), Pandit et al. (J Bone Joint Surg Am 95(15):1365-1372, 2013), National Joint Registry for England, Wales and Northern Ireland: 10th Annual Report 2013 ( http://www.njrcentre.org.uk/njrcentre/Portals/0/Documents/England/Reports/10th_annual_report/NJR%2010th%20Annual%20Report%202013%20B.pdf , 2013), Swedish Knee Arthroplasty Register: Annual Report 2013 ( http://www.myknee.se/pdf/SKAR2013_Eng.pdf , 2013). This single-centre retrospective cohort study reports the 5-year follow-up results of our first 30 consecutively implanted cementless Oxford UKR (OUKR). Clinical outcome was measured using the OKS, AKSS, range of movement and level of pain (visual analogue scale). The results were compared to cemented OUKR in a matched-pair analysis. Implant survival was 89.7%. One revision each was performed due to tibial fracture, progression of osteoarthritis (OA) and inlay dislocation. The 5-year survival rate of the cementless group was 89.7% and of the cemented group 94.1%. Both groups showed excellent postoperative clinical scores. Cementless fixation shows good survival rates and clinical outcome compared to cemented fixation.

  5. Cementless Hip Arthroplasty in Southern Iran, Midterm Outcome and Comparison of Two Designs.

    Science.gov (United States)

    Shahgheraghi, Gholam Hossein; Hashemi, Frcs C Seyed Ali

    2015-09-01

    Cementless hip prosthesis was designed to provide biologic fixation, without the use of cement. The second generation components have shown more reliable bone ingrowths and survival rates. We are reporting a midterm result of two designs of cementless prosthesis in a unique culture with different social habits and expectations. 52 primary cementless total hip arthroplasty in 42 patients with the mean age of 48.8 years were retrospectively studied. Two groups of prosthesis had been implanted: Harris-Galante II (HGII) in 15 and Versys-Trilogy (V-T) in 37 hips, both from Zimmer company. The patients were assessed clinically, radiographically and with Harris hip score, SF36, WOMAC, and MACTAR questionnaires, with 65 months (26-136) mean follow-up. All the V-T prostheses had survived well. Eight of HG II were revised by the last follow-up in 19-102 months. All had undergone acetabular revision and 2 combined with femoral revision. Broken tines of HGII cups were seen in 4 radiographs. The 65 months overall survival was 96.2% for femoral and 84.6% for acetabular components. 90% had good or excellent Harris hip scores. The functional scores were poorer in the HG II group. Pain relief and improved walking were the two main patients' expectations fulfilled in 97.6% and 92.8%, respectively. The outcome of cementless total hip arthroplasty (THA) is satisfactory and comparable with the literature based on the results of function and survival of this small comparative group. The use of HGII acetabular component should be abandoned.

  6. Clinical and radiographic results of 184 consecutive revision total knee arthroplasties placed with modular cementless stems.

    Science.gov (United States)

    Peters, Christopher L; Erickson, Jill A; Gililland, Jeremy M

    2009-09-01

    Clinical and radiographic outcomes of 184 consecutive revision total knee arthroplasties (TKAs) placed with cemented components and press-fit fluted cementless stems were reviewed at average follow-up of 49 months. Revision was performed for septic failure in 53 of 184 knees, periprosthetic fracture in 10 of 184 knees, and aseptic failure in 121 of 184 knees. The press-fit cementless stems were placed to tightly contact the endosteum of the metadiaphyseal area of the femur and tibia. No knees were re-revised for aseptic loosening. There were 15 failures (15/184, 8.2%): 13 were septic failures, 9 of which were recurrence of sepsis and 4 of which were new cases of sepsis. Average Knee Society knee score improved from 134.6 to 167.8 (P < .05). Revision TKA with modular cementless stems provided excellent fixation with no revisions for aseptic loosening. Re-revision for sepsis was the dominant failure mechanism with an overall rate of 7%. Given the increasing prevalence of revision TKA, sepsis prevention strategies should receive increased attention.

  7. Fixation of an Anatomically Designed Cementless Stem in Total Hip Arthroplasty

    Directory of Open Access Journals (Sweden)

    Shigeru Nakamura

    2012-01-01

    Full Text Available Purpose. The Anatomic Fiber Metal plus stem (Zimmer is one of the anatomically designed cementless stems to achieve stable fixation by metaphyseal fit. We studied outcomes of cementless total hip arthroplasty using this stem and possible effects of metaphyseal fit on outcomes. Methods. The cementless total hip arthroplasty using this stem was performed for 155 hips. One hundred and thirty-seven hips of 122 patients were followed for 5 to 16 (mean, 9.7 years and entered into the study. The metaphyseal fit was defined as good or poor in an anteroposterior radiograph after surgery. We studied the fixation of the stem and bone reaction on an anteroposterior radiograph at the final followup. Results. Twelve hips had revision, six acetabular components and six acetabular liners. No stem was revised. The biological fixation of the stem was bone ingrown fixation for 136 hips and unstable for one. The metaphyseal fit was good for 83 hips and poor for 54 hips. There were no differences for stem fixation and bone reaction between the two groups. Conclusions. The fixation of the stem was stable at a mean followup of 9.7 years independently from metaphyseal fit.

  8. Femoral head fracture without hip dislocation

    Directory of Open Access Journals (Sweden)

    Aggarwal Aditya K

    2013-10-01

    Full Text Available 【Abstract】Femoral head fractures without dislocation or subluxation are extremely rare injuries. We report a neglected case of isolated comminuted fracture of femoral head without hip dislocation or subluxation of one year duration in a 36-year-old patient who sustained a high en- ergy trauma due to road traffic accident. He presented with painful right hip and inability to bear full weight on right lower limb with Harris hip score of 39. He received cementless total hip replacement. At latest follow-up of 2.3 years, functional outcome was excellent with Harris hip score of 95. Such isolated injuries have been described only once in the literature and have not been classified till now. The purpose of this report is to highlight the extreme rarity, possible mechanism involved and a novel classification system to classify such injuries. Key words: Femur head; Hip dislocation; Classification; Arthroplasty, replacement, hip

  9. Cementless Porous Tantalum Monoblock Tibia vs Cemented Modular Tibia in Primary Total Knee Arthroplasty: A Meta-Analysis.

    Science.gov (United States)

    Hu, Bin; Chen, Yunlin; Zhu, Hanxiao; Wu, Haobo; Yan, Shigui

    2017-02-01

    With the introduction of new fixation systems and designs, there has been a recent reemergence of interest in cementless fixation of the tibial component in total knee arthroplasty. However, little is known regarding the clinical features and survivorship of the cementless porous tantalum monoblock tibial component compared to the conventional cemented modular tibial component. We conducted a literature search of multiple databases for comparative studies published before June 2015 that investigated the outcomes of cementless porous tantalum monoblock tibia vs conventional cemented modular tibia. A pooled analysis was performed. The outcomes of interest were postoperative functional score, range of motion, Western Ontario and McMaster University Osteoarthritis Index, total complications, reoperation, radiolucent lines, loosening of the tibial component, and length of operation. Six studies involving 977 patients were eligible for the meta-analysis. The use of a cementless porous tantalum monoblock tibial component may associate with a slightly higher functional score, fewer radiolucent lines, and shorter operation. No significant difference was seen in regard to the range of motion, Western Ontario and McMaster University Osteoarthritis Index, total complications, reoperation, and loosening of the component between the 2 groups. However, due to variation among the included studies, the use of cementless porous tantalum monoblock tibia seems to achieve no substantial superiority over that of the conventional cemented modular tibia at 5-year follow-up. Data concerning the long-term prognosis of this novel implant should continue to be collected and analyzed. Copyright © 2016 Elsevier Inc. All rights reserved.

  10. Profiling the third-body wear damage produced in CoCr surfaces by bone cement, CoCr, and Ti6Al4V debris: a 10-cycle metal-on-metal simulator test.

    Science.gov (United States)

    Halim, Thomas; Burgett, Michelle; Donaldson, Thomas K; Savisaar, Christina; Bowsher, John; Clarke, Ian C

    2014-07-01

    Particles of bone cement (polymethyl methacrylate), CoCr and Ti6Al4V were compared for their abrasion potential against CoCr substrates. This appears to be the first study utilizing CoCr and Ti6Al4V particulates to abrade CoCr bearings and the first study profiling the morphology of third-body abrasive wear scratches in a hip simulator. The 5 mg debris allotments (median size range 140-300 µm) were added to cups mounted both inverted and anatomically with metal-on-metal (MOM) bearings in a 10-cycle, hip simulator test. Surface abrasion was characterized by roughness indices and scratch profiles. Compared to third-body abrasion with metal debris, polymethyl methacrylate debris had minimal effect on the CoCr surfaces. In all, 10 cycles of abrasion with metal debris demonstrated that roughness indices (Ra, PV) increased approximately 20-fold from the unworn condition. The scratch profiles ranged 20-108 µm wide and 0.5-2.8 µm deep. The scratch aspect ratio (W/PV) averaged 0.03, and this very low ratio indicated that the 140 µm CoCr beads had plastically deformed to create wide but shallow scratches. There was no evidence of transfer of CoCr beads to CoCr bearings. The Ti64 particles produced similar scratch morphology with the same aspect ratio as the CoCr particulates. However, the titanium particulates also showed a unique ability to flatten and adhere to the CoCr, forming smears and islands of contaminating metal on the CoCr bearings. The morphology of scratches and metal transfer produced by these large metal particulates in the simulator appeared identical to those reported on retrieved metal-on-metal bearings. © IMechE 2014.

  11. The migration patterns of two versions of the Furlong cementless femoral stem: a randomised, controlled trial using radiostereometric analysis.

    Science.gov (United States)

    Simpson, D J; Kendrick, B J L; Hughes, M; Glyn-Jones, S; Gill, H S; Rushforth, G F; Murray, D W

    2010-10-01

    We have evaluated the difference in the migration patterns over two years of two cementless stems in a randomised, controlled trial using radiostereophotogrammetric analysis (RSA). The implants studied were the Furlong HAC stem, which has good long-term results and the Furlong Active stem, which is a modified version of the former designed to minimise stress concentrations between the implant and bone, and thus to improve fixation. A total of 23 Furlong HAC and 20 Furlong Active stems were implanted in 43 patients. RSA examinations were carried out immediately post-operatively and at six, 12 and 24 months post-operatively. The subsidence during the first year in the Furlong HAC stem, was approximately one-third that of the Furlong Active stem, the measured mean subsidence of the femoral head at six months being 0.27 mm (95% confidence interval (CI) 0.03 to 0.51) and 0.99 mm (95% CI 0.38 to 1.60), respectively (p = 0.03). One Active stem continued to subside during the second year. All hips, regardless of the type of stem were clinically successful as judged by the Oxford hip score and a derived pain score without any distinction between the two types of stem. The initial stability of the Furlong Active stem was not as good as the established stem which might compromise osseo-integration to the detriment of long-term success. The changes in the geometry of the stem, to minimise stress have affected the attainment of initial stability.

  12. Low Frequency of Early Complications With Dual-mobility Acetabular Cups in Cementless Primary THA.

    Science.gov (United States)

    Chughtai, Morad; Mistry, Jaydev B; Diedrich, Aloise M; Jauregui, Julio J; Elmallah, Randa K; Bonutti, Peter M; Harwin, Steven F; Malkani, Arthur L; Kolisek, Frank R; Mont, Michael A

    2016-10-01

    Dislocation complicates 1% to 5% of primary total hip arthroplasties (THAs). As a result, some surgeons consider dual-mobility articulations, which are usually used in the revision setting to decrease the likelihood of dislocation, as an option for primary THA. However, few studies have evaluated their use in this setting. (1) What is the cup survivorship when the dual-mobility articulation is used in the setting of primary THA? (2) What are the clinical outcomes with this approach? (3) What are the radiographic outcomes? (4) What are the complications of dual-mobility articulations in primary THA? Between 2011 and 2013, the five participating surgeons performed 495 cementless primary THAs. During that time, one of the five surgeons used dual-mobility articulations for all THAs, and the other four used it whenever the acetabular cup size was 52 mm or greater to enable a 28-mm head. Of the 495 patients, 453 (92%) were performed using this device. Smaller patients were treated with a standard THA. Of the 453 patients, a total of 43 patients (10%) were lost to followup before the 2-year minimum. The resulting 410 patients who were included in the analysis (164 men, 246 women) had a mean age of 64 years (SD, 12 years). The mean followup was 3 years (SD, 0.7 years). We performed Kaplan-Meier analyses to assess survivorship to aseptic failure and all-cause acetabular component survivorship. Clinical outcomes were evaluated using the Harris hip score (HHS); radiographs were assessed for cup migration, progressive radiolucencies, and positional changes of the components; and any surgery-related complications were recorded. The survivorship to aseptic failure and all-cause acetabular component survivorship was 99.8% (failures, n = 1) (95% confidence interval [CI], 4.517-4.547) and 99.3% (failures, aseptic, n = 1; septic, n = 2) (95% CI, 4.494-4.543); one hip had trunnion notching caused by impingement of a malpositioned cup, which was treated with revision of the cup and

  13. Third-body Wear Damage Produced in CoCr Surfaces by Hydroxyapatite and Alumina Ceramic Debris: A 10-cycle Metal-on-Metal Simulator Study

    Directory of Open Access Journals (Sweden)

    Thomas Halim

    2015-12-01

    Full Text Available Ceramic particles are believed to be particularly abrasive due to their extreme hardness. Ceramic debris has been reported in retrieved total hip arthroplasty (THA due to chipping and fracture of alumina components or by flaking of hydroxyapatite from implant coatings. However there appears to be no abrasion ranking of such particle behavior. The hypotheses in this study were, i alumina particles would create large scratches in CoCr surfaces and ii hydroxyapatite would produce very mild scratching comparable to bone-cement particles. Hydroxyapatite beads came in two types of commercial powders while the flakes were scraped from retrieved femoral stems. Alumina beads came in two commercial powders and flakes were retrieved from a fractured ceramic head. Particle morphologies were determined by SEM and CoCr surface damage by interferometry and SEM. Six 38-mm MOM were mounted inverted in a hip simulator and run with ceramic particles inserted for a 10-second test. Surface-roughness ranking after 10-second abrasion test revealed that bone cement and hydroxyapatite produced least damage to CoCr surfaces while alumina produced the most. Alumina increased surface roughness 19-fold greater than either hydroxyapatite or bone-cement particles. The alumina debris produced numerous scratches typically 20-80 µm wide with some up to 140µm wide. Surprisingly the alumina beads and flakes were pulverized within the 10-second test interval and remained adherent to the CoCr surfaces. Additionally, the hydroxyapatite although also a ceramic had no more effect on CoCr than the bone-cement debris. Use of well-characterized and commercially available alumina and hydroxyapatite powders appeared advantageous for abrasion tests. These new data indicated that such ceramic powders have merit.

  14. Cemented, cementless, and hybrid prostheses for total hip replacement: cost effectiveness analysis.

    Science.gov (United States)

    Pennington, Mark; Grieve, Richard; Sekhon, Jasjeet S; Gregg, Paul; Black, Nick; van der Meulen, Jan H

    2013-02-27

    To compare the cost effectiveness of the three most commonly chosen types of prosthesis for total hip replacement. Lifetime cost effectiveness model with parameters estimated from individual patient data obtained from three large national databases. English National Health Service. Adults aged 55 to 84 undergoing primary total hip replacement for osteoarthritis. Total hip replacement using either cemented, cementless, or hybrid prostheses. Cost (£), quality of life (EQ-5D-3L, where 0 represents death and 1 perfect health), quality adjusted life years (QALYs), incremental cost effectiveness ratios, and the probability that each prosthesis type is the most cost effective at alternative thresholds of willingness to pay for a QALY gain. Lifetime costs were generally lowest with cemented prostheses, and postoperative quality of life and lifetime QALYs were highest with hybrid prostheses. For example, in women aged 70 mean costs were £6900 ($11 000; €8200) for cemented prostheses, £7800 for cementless prostheses, and £7500 for hybrid prostheses; mean postoperative EQ-5D scores were 0.78, 0.80, and 0.81, and the corresponding lifetime QALYs were 9.0, 9.2, and 9.3 years. The incremental cost per QALY for hybrid compared with cemented prostheses was £2500. If the threshold willingness to pay for a QALY gain exceeded £10 000, the probability that hybrid prostheses were most cost effective was about 70%. Hybrid prostheses have the highest probability of being the most cost effective in all subgroups, except in women aged 80, where cemented prostheses were most cost effective. Cemented prostheses were the least costly type for total hip replacement, but for most patient groups hybrid prostheses were the most cost effective. Cementless prostheses did not provide sufficient improvement in health outcomes to justify their additional costs.

  15. Good mid- to long-term THA outcomes with a modified cementless rectangular biconical stem design.

    Science.gov (United States)

    Iori, Stefano; Viganò, Roberto

    2016-07-25

    Second- and third-generation cementless Zweymüller stems have achieved good long-term outcomes in total hip arthroplasty (THA). The PPF cementless proximal press-fit femoral stem (Biomet Inc.) is based on the Zweymüller stem, with some prominent design differences. This study was designed to assess its performance in terms of survivorship, clinical function, and radiographic outcomes. We retrospectively analysed 250 patients (303 hips) who underwent THA between 1998 and 2011. Patients attended a follow-up visit a mean 10.9 ± 2.6 years after the procedure. All patients underwent radiographic examination and were clinically assessed for Forgotten Joint Score (FJS) and pain visual analogue scale (VAS). Survivorship was calculated using Kaplan-Meier analysis. Clinical data were available for 142 patients (192 hips) and radiographic data for 79 patients (109 hips). Stem survival was 99.1% (95% confidence interval [CI] 96.6%-99.8%) at 10 years and 95.6% (95% CI 96.6%-99.8%) at 15 years. The median postoperative FJS was 91 (interquartile range [IQR], 75-100). The median VAS score was 0 (IQR, 0-2). Radiolucent lines were observed in 47 hips (43.1%). 25 hips (22.9%) had Grade I ossification, 17 (15.6%) Grade II, and 2 (1.8%) Grade III. 12 hips (11.0%) had osteolysis in at least 1 femoral zone. The cementless proximal press-fit femoral stem was associated with good mid- to long-term survival and functional outcomes. The current design can be considered equivalent to the second- and third-generation Zweymüller stems.

  16. Does osteoporosis reduce the primary tilting stability of cementless acetabular cups?

    Science.gov (United States)

    von Schulze Pellengahr, Christoph; von Engelhardt, Lars V; Wegener, Bernd; Müller, Peter E; Fottner, Andreas; Weber, Patrick; Ackermann, Ole; Lahner, Matthias; Teske, Wolfram

    2015-04-21

    Cementless hip cups need sufficient primary tilting stability to achieve osseointegration. The aim of the study was to assess differences of the primary implant stability in osteoporotic bone and in bone with normal bone density. To assess the influence of different cup designs, two types of threaded and two types of press-fit cups were tested. The maximum tilting moment for two different cementless threaded cups and two different cementless press-fit cups was determined in macerated human hip acetabuli with reduced (n=20) and normal bone density (n=20), determined using Q-CT. The tilting moments for each cup were determined five times in the group with reduced bone density and five times in the group with normal bone density, and the respective average values were calculated. The mean maximum extrusion force of the threaded cup Zintra was 5670.5 N (max. tilting moment 141.8 Nm) in bone with normal density and.5748.3 N (max. tilting moment 143.7 Nm) in osteoporotic bone. For the Hofer Imhof (HI) threaded cup it was 7681.5 N (192.0 Nm) in bone with normal density and 6828.9 N (max. tilting moment 170.7 Nm) in the group with osteoporotic bone. The mean maximum extrusion force of the macro-textured press-fit cup Metallsockel CL was 3824.6 N (max. tilting moment 95.6 Nm) in bone with normal and 2246.2 N (max. tilting moment 56.2 Nm) in osteoporotic bone. For the Monoblock it was 1303.8 N (max. tilting moment 32.6 Nm) in normal and 1317 N (max. tilting moment 32.9 Nm) in osteoporotic bone. There was no significance. A reduction of the maximum tilting moment in osteoporotic bone of the ESKA press-fit cup Metallsockel CL was noticed. Results on macerated bone specimens showed no statistically significant reduction of the maximum tilting moment in specimens with osteoporotic bone density compared to normal bone, neither for threaded nor for the press-fit cups. With the limitation that the results were obtained using macerated bone, we could not detect any restrictions for

  17. Antibacterial Efficacy of a New Gentamicin-Coating for Cementless Prostheses Compared to Gentamicin-Loaded Bone Cement

    NARCIS (Netherlands)

    Neut, Danielle; Dijkstra, Rene J. B.; Thompson, Jonathan I.; van der Mei, Henny C.; Busscher, Henk J.

    2011-01-01

    Cementless prostheses are increasingly popular but require alternative prophylactic measures than the use of antibiotic-loaded bone cements. Here, we determine the 24-h growth inhibition of gentamicin-releasing coatings from grit-blasted and porous-coated titanium alloys, and compare their

  18. Digital tomosynthesis with metal artifact reduction for assessing cementless hip arthroplasty: a diagnostic cohort study of 48 patients

    Energy Technology Data Exchange (ETDEWEB)

    Tang, Hao; Yang, Dejin; Guo, Shengjie; Tang, Jing; Liu, Jian; Wang, Dacheng; Zhou, Yixin [Beijing Jishuitan Hospital, Fourth Clinical College of Peking University, Department of Orthopaedic Surgery, Beijing (China)

    2016-11-15

    For postoperative imaging assessment of cementless hip arthroplasty, radiography and computed tomography (CT) were restricted by overlapping structures and metal artifacts, respectively. A new tomosynthesis with metal artifact reduction (TMAR) is introduced by using metal extraction and ordered subset-expectation maximization (OS-EM) reconstruction. This study investigated the effectiveness of TMAR in assessing fixation stability of cementless hip arthroplasty components. We prospectively included 48 consecutive patients scheduled for revision hip arthroplasty in our hospital, with 41 femoral and 35 acetabular cementless components available for evaluation. All patients took the three examinations of radiography, CT, and TMAR preoperatively, with intraoperative mechanical tests, and absence or presence of osteointegration on retrieved prosthesis as reference standards. Three senior surgeons and four junior surgeons evaluated these images independently with uniform criteria. For TMAR, 82 % diagnoses on the femoral side and 84 % diagnoses on the acetabular side were accurate. The corresponding values were 44 and 67 % for radiography, and 39 % and 74 % for CT. Senior surgeons had significantly higher accuracy than junior surgeons by radiography (p < 0.05), but not by TMAR or CT. By minimizing metal artifacts in the bone-implant interface and clearly depicting peri-implant trabecular structures, the TMAR technique improved the diagnostic accuracy of assessing fixation stability of cementless hip arthroplasty, and shortened the learning curve of less experienced surgeons. Level II, diagnostic cohort study. (orig.)

  19. Toxicology of wear particles of cobalt-chromium alloy metal-on-metal hip implants Part II: Importance of physicochemical properties and dose in animal and in vitro studies as a basis for risk assessment.

    Science.gov (United States)

    Madl, Amy K; Kovochich, Michael; Liong, Monty; Finley, Brent L; Paustenbach, Dennis J; Oberdörster, Günter

    2015-07-01

    The objective of the Part II analysis was to evaluate animal and in vitro toxicology studies of CoCr particles with respect to their physicochemistry and dose relevance to metal-on-metal (MoM) implant patients as derived from Part I. In the various toxicology studies, physicochemical characteristics were infrequently considered and administered doses were orders of magnitude higher than what occurs in patients. Co was consistently shown to rapidly release from CoCr particles for distribution and elimination from the body. CoCr micron sized particles appear more biopersistent in vivo resulting in inflammatory responses that are not seen with similar mass concentrations of nanoparticles. We conclude, that in an attempt to obtain data for a complete risk assessment, future studies need to focus on physicochemical characteristics of nano and micron sized particles and on doses and dose metrics relevant to those generated in patients or in properly conducted hip simulator studies. Copyright © 2015 Elsevier Inc. All rights reserved.

  20. Lower preoperative Hounsfield unit values are associated with intra-operative fractures in cementless bipolar hemiarthroplasty.

    Science.gov (United States)

    Kim, Seung-Ju; Park, Hyun-Soo; Lee, Dong-Woo; Kim, Jong Hun

    2017-12-07

    The use of Hounsfield units (HU) from CT scanning to assess regional BMD has been described. Therefore, we evaluated whether HU could be used to identify osteoporosis of the proximal part of the femur. The results showed that HU assessment is associated with the presence of intra-operative fracture during arthroplasty. The aim with this study was to determine the association of preoperative Hounsfield unit (HU) in hip computed tomography (CT) with intra-operative osteoporotic fracture during cementless hemiarthroplasty. In this retrospective study, we reviewed all patients who underwent cementless bipolar hemiarthroplasty for femoral neck fractures between 2014 and 2016. Patients with intra-operative metaphyseal fractures (n = 25) during surgery were identified from a retrospectively collected patient database and matched with nonfracture controls (n = 75) on the basis of age and sex. The differences between patients with intra-operative fractures and without intra-operative fractures were compared regarding preoperative HU. Correlations of HU value of femur neck with BMD and T scores were determined. Analysis of HU values at the fracture level showed a significantly lower value in the fracture group than in the controls (1186 vs 1340, p = 0.005). The correlation between HU and BMD of femur neck was significant (r 2 = 0.347; p operative fracture during bipolar hemiarthroplasty. We believe that HU values of the proximal femur could be used to assess local bone quality.

  1. Cementing Constrained Liners Into Secure Cementless Shells: A Minimum 15-Year Follow-Up Study.

    Science.gov (United States)

    Young, Grant H; Abdel, Matthew P; Amendola, Richard L; Goetz, Devon D; Lewallen, David G; Callaghan, John J

    2017-11-01

    The authors and others have previously described the technique of cementing constrained liners into secure cementless acetabular shells and reported the short-term, average 3.9-year follow-up, using that technique. The purpose of the present study was to report the minimum 15-year follow-up of this same cohort. Between 1988 and 2000, 31 consecutive constrained liners of one design were cemented into well-fixed, well-positioned cementless acetabular shells at 3 institutions. Average age at surgery was 72 years (range, 31-91 years). Indications for the procedure were recurrent hip dislocation in 16 cases and intraoperative instability in 15 cases. Patients were evaluated for revision for failure of the device and revision for any reason. At minimum 15-year follow-up, there was 1 patient lost to follow-up. Three hips (9.7%) were revised for failure of the device and 5 hips (16.1%) were revised for any reason. At minimum 15-year follow-up, considering the complexity of cases, there was excellent medium-term durability of this construct. Copyright © 2017 Elsevier Inc. All rights reserved.

  2. Preclinical trial of a novel surface architecture for improved primary fixation of cementless orthopaedic implants.

    Science.gov (United States)

    Harrison, Noel; Field, John R; Quondamatteo, Fabio; Curtin, William; McHugh, Peter E; Mc Donnell, Pat

    2014-09-01

    A new surface architecture for cementless orthopaedic implants (OsteoAnchor), which incorporates a multitude of tiny anchor features for enhancing primary fixation, was tested in an ovine hemi-arthroplasty pilot study. Test animals were implanted with a hip stem component incorporating the OsteoAnchor surface architecture produced using additive layer manufacturing and control animals were implanted with stems containing a standard plasma sprayed titanium coating. Intra-operative surgeon feedback indicated that superior primary fixation was achieved for the OsteoAnchor stems and rapid return to normal gait and load bearing was observed post-operation. Following a 16-week recovery time, histological evaluation of the excised femurs revealed in-growth of healthy bone into the porous structure of the OsteoAnchor stems. Bone in-growth was not achieved for the plasma sprayed stems. These results indicate the potential for the OsteoAnchor surface architecture to enhance both the initial stability and long term lifetime of cementless orthopaedic implants. Copyright © 2014 Elsevier Ltd. All rights reserved.

  3. A genetic algorithm based multi-objective shape optimization scheme for cementless femoral implant.

    Science.gov (United States)

    Chanda, Souptick; Gupta, Sanjay; Kumar Pratihar, Dilip

    2015-03-01

    The shape and geometry of femoral implant influence implant-induced periprosthetic bone resorption and implant-bone interface stresses, which are potential causes of aseptic loosening in cementless total hip arthroplasty (THA). Development of a shape optimization scheme is necessary to achieve a trade-off between these two conflicting objectives. The objective of this study was to develop a novel multi-objective custom-based shape optimization scheme for cementless femoral implant by integrating finite element (FE) analysis and a multi-objective genetic algorithm (GA). The FE model of a proximal femur was based on a subject-specific CT-scan dataset. Eighteen parameters describing the nature of four key sections of the implant were identified as design variables. Two objective functions, one based on implant-bone interface failure criterion, and the other based on resorbed proximal bone mass fraction (BMF), were formulated. The results predicted by the two objective functions were found to be contradictory; a reduction in the proximal bone resorption was accompanied by a greater chance of interface failure. The resorbed proximal BMF was found to be between 23% and 27% for the trade-off geometries as compared to ∼39% for a generic implant. Moreover, the overall chances of interface failure have been minimized for the optimal designs, compared to the generic implant. The adaptive bone remodeling was also found to be minimal for the optimally designed implants and, further with remodeling, the chances of interface debonding increased only marginally.

  4. Influence of the positioning of a cementless glenoid prosthesis on its interface micromotions.

    Science.gov (United States)

    Suárez, D R; van der Linden, J C; Valstar, E R; Broomans, P; Poort, G; Rozing, P M; van Keulen, F

    2009-10-01

    The positioning of the glenoid component in total shoulder arthroplasty is complicated by the limited view during operation. Malalignment and/or motion of the glenoid component with respect to the bone can be a cause of, or contribute to, failure of the implant. The aim of this paper is to determine the effect of the positioning of a cementless glenoid component on the micromotions between the implant and the bone during normal loading after surgery. For this study a three-dimensional finite element model of a complete scapula with a cementless glenoid component was used. In total, eight positions of the upper arm in both abduction and anteflexion were chosen to represent the patient's arm movement postoperatively. A previously published musculoskeletal model was used to determine the joint and muscle forces on the scapula with implant in each arm position. Five different alignments of the glenoid component (neutral, anterior, inferior, posterior, and superior inclinations), two different implantation depths ('optimal' and 'deeper' implantations), and two bone qualities (healthy and rheumatoid arthritis (RA) bone) were considered. Inclinations of 10 degrees with respect to a neutral alignment did not affect the overall interface micromotions in the optimal implantation depth. However, when the implantation depth was 3 mm deeper, anterior and inferior inclinations were more favourable than a neutral alignment and other inclinations. Micromotions in RA bone were always larger than in healthy bone.

  5. Total hip arthroplasty with cementless cup after acetabular fracture

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    Marcelo Alfonso Lugones

    2012-12-01

    Full Text Available Background Acetabular fractures are a common cause of degenerative hip arthritis. The incidence of post-traumatic osteoarthritis has been reported between 12% and 57% and avascular necrosis of the femoral head may occur in 2% to 40% after posterior fracture dislocation. The fracture is often caused by major trauma in road accidents, at work or during sports, and patients usually present for total hip replacement (THR at an earlier age than the general arthritic population. We describe and analyze our patients with uncemented acetabular reconstruction in post-traumatic arthritis and compare them with THR in non-traumatic arthritis. Methods We retrospectively evaluated 19 patients who underwent uncemented acetabular reconstruction due to post-traumatic arthritis secondary to acetabular fracture. Results The average age at the time of arthroplasty was 52.2 years (19-83. The age at the time of fracture was 47.9 years (16-81. The average time between the acetabular fracture and THR was 52.4 months (4-360. The average follow-up was 4.25 years. No acetabular component loosening or infections were seen in either group. The Harris Hip Score at an average follow-up of 4.25 years was 89.3 (57-99. The follow-up in the control group with non-traumatic arthritis was 4.9 years, and the Harris Hip Score was 94.1 points (78-100. There were no significant difference in the Harris Hip Score between groups (p = 0.24. Conclusion Uncemented acetabular reconstruction in post-traumatic arthritis secondary to acetabular fracture is a more difficult procedure than routine arthroplasty in patient with non-traumatic arthritis. In the short-term there are no clinical or radiographic differences in THR with uncemented acetabular cups in post-traumatic arthritis patients compared to patients with non-traumatic arthritis.

  6. Cementless fixation in total knee arthroplasty: down the boulevard of broken dreams - affirms.

    Science.gov (United States)

    Ranawat, C S; Meftah, M; Windsor, E N; Ranawat, A S

    2012-11-01

    There has been a recent increase in interest for non-cemented fixation in total knee arthroplasty (TKA), however the superiority of cement fixation is an ongoing debate. Whereas the results based on Level III and IV evidence show similar survivorship rates between the two types of fixation, Level I and II evidence strongly support cemented fixation. United Kingdom, Australia, Sweden, and New Zealand registry data show lower failure rates and greater usage of cemented than non-cemented fixation. Case series studies have also indicated greater functional outcomes and lower revision rates among cemented TKAs. Non-cemented fixation involves more patellofemoral complications, including increased susceptibility to wear due to a thinner polyethylene bearing on the cementless metal-backed component. The combination of results from registry data, prospective randomised studies, and meta-analyses support the current superiority of cemented fixation in TKAs.

  7. Total hip arthroplasty using a cylindrical cementless stem in patients with a small physique.

    Science.gov (United States)

    Nakamura, Yoshihide; Mitsui, Hiromasa; Kikuchi, Akira; Toh, Satoshi; Katano, Hiroshi

    2011-01-01

    We performed total hip arthroplasty using an anatomic medullary locking cementless stem for small-physique patients from 1988 to 1995. We conducted a retrospective study of 50 joints in 44 cases, including 40 developmentally dysplastic hips followed for 12 to 20 years (average, 15.1 years). Average height and body weight were 152 cm and 56 kg (5.0 ft and 124 lb), respectively, with an average body mass index of 24.2. Twelve joints (24%) were revised for acetabular-sided failures. Forty-eight stems (96%) showed bone ingrowth fixation, and there were no unstable stems. The simple cylindrical shape of the distal portion of the AML stem was less affected by deformity of the proximal femur of developmental dysplasia of the hip in patients with a small physique, and both clinically and radiologically good results were confirmed at long-term follow-up. Copyright © 2011 Elsevier Inc. All rights reserved.

  8. Utilizing of the metallurgical slag for production of cementless concrete mixtures

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    D. Baricová

    2012-10-01

    Full Text Available In process of pig iron, steel and cast iron production besides main product, also secondary products are formed, that have character of secondary raw materials and industrial wastes. The most abundant secondary product originating in the metallurgical process is furnace slag. Total amount of accured slag, also its chemical, mineralogical, physical – chemical properties and similarity with natural stones predestinate its utilisation in different fields of industry. The contribution deals with production of cementless concrete mixtures, where the main parts were formed by blast furnace granulated slag grinded and different gravel slag from blast furnace, oxygen converter and electric arc furnace. As activators of solidification different kinds of water glass were tested.

  9. Biomechanical Study on Distal Filling Effects in Cementless Total Hip Replacement

    Science.gov (United States)

    Chae, Soo-Won; Lee, Jun-Hyoung; Choi, Hyung-Yun

    In cementless total hip replacement, initial stability of the femoral component is important in the long term fixation of the femoral stem. Initial stability is closely related to the relative displacement between the prosthesis and the cancellous bone of the proximal femur. After implantation of the prosthesis, the surrounding bone is partially shielded from load carrying and starts to resorb. Stress shielding causes the loss of the proximal bone. The stress distribution of femur must be assessed to predict stress shielding. The initial stability and the stress shielding were investigated for two loading conditions approximating a single leg stance and stair climbing. Two types of stems involving a distal filling and a distal short stem were studied by the finite element method to investigate the biomechanical distal filling effects. The distal short stem produced less stress shielding at the proximal bone than the distal filling stem, while both types of stems seemed to satisfy the initial stability requirement.

  10. A biodegradable gentamicin-hydroxyapatite-coating for infection prophylaxis in cementless hip prostheses.

    Science.gov (United States)

    Neut, D; Dijkstra, R J; Thompson, J I; Kavanagh, C; van der Mei, H C; Busscher, H J

    2015-01-02

    A degradable, poly (lactic-co-glycolic acid) (PLGA), gentamicin-loaded prophylactic coating for hydroxyapatite (HA)-coated cementless hip prostheses is developed with similar antibacterial efficacy as offered by gentamicin-loaded cements for fixing traditional, cemented prostheses in bone. We describe the development pathway, from in vitro investigation of antibiotic release and antibacterial properties of this PLGA-gentamicin-HA-coating in different in vitro models to an evaluation of its efficacy in preventing implant-related infection in rabbits. Bone in-growth in the absence and presence of the coating was investigated in a canine model. The PLGA-gentamicin-HA-coating showed high-burst release, with antibacterial efficacy in agar-assays completely disappearing after 4 days, minimising risk of inducing antibiotic resistance. Gentamicin-sensitive and gentamicin-resistant staphylococci were killed by the antibiotic-loaded coating, in a simulated prosthesis-related interfacial gap. PLGA-gentamicin-HA-coatings prevented growth of bioluminescent staphylococci around a miniature-stem mounted in bacterially contaminated agar, as observed using bio-optical imaging. PLGA-gentamicin-HA-coated pins inserted in bacterially contaminated medullary canals in rabbits caused a statistically significant reduction in infection rates compared to HA-coated pins without gentamicin. Bone ingrowth to PLGA-gentamicin-HA-coated pins, in condylar defects of Beagle dogs was not impaired by the presence of the degradable, gentamicin-loaded coating. In conclusion, the PLGA-gentamicin-HA-coating constitutes an effective strategy for infection prophylaxis in cementless prostheses.

  11. [First clinical experiences with a new cementless knee endoprosthesis for the dog].

    Science.gov (United States)

    Behrend, A; Bonin, T; Hach, V

    2013-01-01

    This paper reports on the clinical application and first experiences of a newly developed cementless knee endoprosthesis for dogs. The GenuSys knee-endoprosthesis was implanted in 23 knees of 22 dogs with severe gonarthritis and a history of pain. Their body weight ranged from 28 to 55 kg, their age between 5 and 12 years. This knee implant for dogs is a cementless "mobile bearing prosthesis". An additional fixation with one screw is necessary in the femoral component. Currently, there are four standard sizes of the prosthesis available. At the end of the study, 16 of 22 controlled patients (72.7%) were fully weightbearing on the operated limb or only showed a discreet lameness. We observed no complications in 12 cases (54.5%). In 10 cases problems in the course of healing were detected and made or would have made reoperation necessary. The complications noted were subluxation (n = 6, 27.3%), wound infection (n = 3, 13.6%) and a serious decrease in the range of motion (n = 1, 4.5%). Four of these 10 patients (40%) were subsequently healed through surgery. The remaining six dogs (27.3%) were euthanized or underwent arthrodesis of the leg. Sixteen of 22 dogs (72.2%) showed much better weightbearing and an increased quality of life after endoprosthesis of the knee. Although the complication rate was high, we expect better results in the future due to improvements in the equipment and surgical procedure. A definitive conclusion can only be made based on the results of a long-term study.

  12. Revision Hip Arthroplasty Using a Modular, Cementless Femoral Stem: Intermediate-Term Follow-Up.

    Science.gov (United States)

    Sivananthan, Sureshan; Lim, Chin-Tat; Narkbunnam, Rapeepat; Sox-Harris, Alex; Huddleston, James I; Goodman, Stuart B

    2017-04-01

    Modular femoral stem provides flexibility in femoral reconstruction, ensuring improved "fit and fill". However, there are risks of junction failure and corrosion, as well as cost concerns in the use of modular femoral stems. We reviewed prospectively-gathered clinical and radiographic data on revision total hip arthroplasties (THAs) performed from 2001-2007 using modular, cementless femoral component performed by the 2 senior authors. Patients with a minimum follow-up of 7 years were included in this study. Sixty-four patients (68 hips) with a median age of 68 ± 14 years (range 40-92 years) at revision THA were included. The median follow-up was 11.0 ± 1.8 years (range 7-14). Harris hip score, femoral stem subsidence, and stem osseointegration were recorded. The Harris hip score improved from an average of 38.1-80.1 (P dislocations. Seven patients underwent reoperations, 3 of which did not involve the stem. Four stems required revision because of infection, recurrent dislocation, or suboptimal implant position. Survival rates for any reasons and revision for femoral stems were 90% and 94%, respectively, at the most recent follow-up. Four stems subsided more than 5 mm, but established stable osseointegration thereafter. Seven nonloose stems (10.2%) demonstrated radiolucent lines in Gruen zones 1 and 7. No complications regarding the modular junction were encountered. Modular, cementless, extensively porous-coated femoral components have demonstrated intermediate-term clinical and radiographic success. Initial distal intramedullary fixation ensures stability, and proximal modularity further maximizes fit and fill. Copyright © 2016 Elsevier Inc. All rights reserved.

  13. Prospective study of the cementless "New Wave" total knee mobile-bearing arthroplasty: 8-year follow-up.

    Science.gov (United States)

    Normand, Xavier; Pinçon, Jean-Louis; Ragot, Jean-Marie; Verdier, Régis; Aslanian, Thierry

    2015-02-01

    One of the main factors affecting the survival of a total knee arthroplasty (TKA) is the fixation method. The constraints placed on the bone-implant interface of a mobile-bearing TKA must be taken in account during the design and evaluation phases. For more than two decades, calcium phosphate ceramics, particularly hydroxyapatitis, have been used in Europe to accelerate the bone integration of cementless implants. A prospective study of patients continuously recruited by three senior surgeons at three French private hospitals has been carried out. There were no exclusion criteria. Eighty-four (84) cementless mobile-bearing total knee prosthesis of the brand "New Wave" were implanted in 74 patients over a 2-year period (2004-2005). Implant survival at 8 years was 95% [with a confidence interval of 95%: 80.2-96.4%] when revision for any cause was defined as the endpoint. Five implants required surgical revision to exchange all or part of the implant: two for aseptic loosening of tibial component, one for osteolysis, one for persistent flessum (30°) and one for tibial periprosthetic fracture. Completely integrated implants and event-free outcomes were recorded in 91.4% of the cases at eight-year follow-up. The Hospital for Special Surgery score significantly improved from 56.8/100 points before the surgery to 83.9/100 points at the last follow-up (p < 0.05). Radiologically, only one patient had radiolucent lines around the tibial and femoral components. This cementless total knee prosthesis yielded good medium-term survival. Cementless arthroplasty can generate solid and durable bone fixation in this total weight-bearing implant, and it seems that the hidroxyapathitis surface in this series stimulate the bone integration at the bone-implant interface.

  14. Migration pattern of cementless press fit cups in the presence of stabilizing screws in total hip arthroplasty

    Directory of Open Access Journals (Sweden)

    Zilkens C

    2011-03-01

    Full Text Available Abstract The aim of this study was to evaluate the initial acetabular implant stability and late acetabular implant migration in press fit cups combined with screw fixation of the acetabular component in order to answer the question whether screws are necessary for the fixation of the acetabular component in cementless primary total hip arthroplasty. One hundred and seven hips were available for follow-up after primary THA using a cementless, porous-coated acetabular component. A total of 631 standardized radiographs were analyzed digitally by the "single-film-x-ray-analysis" method (EBRA. One hundred 'and one (94.4% acetabular components did not show significant migration of more than 1 mm. Six (5.6% implants showed migration of more than 1 mm. Statistical analysis did not reveal preoperative patterns that would identify predictors for future migration. Our findings suggest that the use of screw fixation for cementless porous- coated acetabular components for primary THA does not prevent cup migration.

  15. CoCr wear particles generated from CoCr alloy metal-on-metal hip replacements, and cobalt ions stimulate apoptosis and expression of general toxicology-related genes in monocyte-like U937 cells

    Energy Technology Data Exchange (ETDEWEB)

    Posada, Olga M., E-mail: O.M.PosadaEstefan@leeds.ac.uk [Biomedical Engineering Department, University of Strathclyde, Wolfson Centre, Glasgow G4 0NW (United Kingdom); Gilmour, Denise [Pure and Applied Chemistry Department, University of Strathclyde, Thomas Graham Building, Glasgow G1 1XL (United Kingdom); Tate, Rothwelle J., E-mail: r.j.tate@strath.ac.uk [Strathclyde Institute for Pharmacy and Biomedical Sciences, University of Strathclyde, Glasgow G4 0RE (United Kingdom); Grant, M. Helen [Biomedical Engineering Department, University of Strathclyde, Wolfson Centre, Glasgow G4 0NW (United Kingdom)

    2014-11-15

    Cobalt-chromium (CoCr) particles in the nanometre size range and their concomitant release of Co and Cr ions into the patients' circulation are produced by wear at the articulating surfaces of metal-on-metal (MoM) implants. This process is associated with inflammation, bone loss and implant loosening and led to the withdrawal from the market of the DePuy ASR™ MoM hip replacements in 2010. Ions released from CoCr particles derived from a resurfacing implant in vitro and their subsequent cellular up-take were measured by ICP-MS. Moreover, the ability of such metal debris and Co ions to induce both apoptosis was evaluated with both FACS and immunoblotting. qRT-PCR was used to assess the effects on the expression of lymphotoxin alpha (LTA), BCL2-associated athanogene (BAG1), nitric oxide synthase 2 inducible (NOS2), FBJ murine osteosarcoma viral oncogene homolog (FOS), growth arrest and DNA-damage-inducible alpha (GADD45A). ICP-MS showed that the wear debris released significant (p < 0.05) amounts of Co and Cr ions into the culture medium, and significant (p < 0.05) cellular uptake of both ions. There was also an increase (p < 0.05) in apoptosis after a 48 h exposure to wear debris. Analysis of qRT-PCR results found significant up-regulation (p < 0.05) particularly of NOS2 and BAG1 in Co pre-treated cells which were subsequently exposed to Co ions + debris. Metal debris was more effective as an inducer of apoptosis and gene expression when cells had been pre-treated with Co ions. This suggests that if a patient receives sequential bilateral CoCr implants, the second implant may be more likely to produce adverse effects than the first one. - Highlights: • Effects of CoCr nanoparticles and Co ions on U937 cells were investigated. • Ions released from wear debris play an important role in cellular response, • Toxicity of Co ions could be related to NO metabolic processes and apoptosis. • CoCr particles were a more effective inducer of apoptosis after cell

  16. Retrospective cohort study of the performance of the Pinnacle metal on metal (MoM) total hip replacement: a single-centre investigation in combination with the findings of a national retrieval centre.

    Science.gov (United States)

    Langton, David John; Sidaginamale, Raghavendra Prasad; Avery, Peter; Waller, Sue; Tank, Ghanshyabhai; Lord, James; Joyce, Thomas; Cooke, Nick; Logishetty, Raj; Nargol, Antoni Viraf Francis

    2016-04-29

    To determine risk factors for revision in patients implanted with a commonly used metal on metal (MoM) hip replacement. Retrospective cohort study in combination with a prospective national retrieval study (Northern Retrieval Registry (NRR)). Combined orthopaedic unit in combination with the NRR. All patients implanted with a DePuy Pinnacle MoM hip prostheses by the 2 senior authors were invited to attend for a review which included clinical examination, blood metal ion measurements, radiographs and targeted imaging. Explanted components underwent wear analysis using validated methodology and these results were compared with those obtained from the NRR. 489 MoM Pinnacle hips were implanted into 434 patients (243 females and 191 males). Of these, 352 patients attended the MoM recall clinics. 64 patients had died during the study period. For the purposes of survival analysis, non-attendees were assumed to have well-functioning prostheses. The mean follow-up of the cohort as a whole was 89 months. 71 hips were revised. Prosthetic survival for the whole cohort was 83.6% (79.9-87.3) at 9 years. The majority of explanted devices exhibited signs of taper junction failure. Risk factors for revision were bilateral MoM prostheses, smaller Pinnacle liners, and implantation in 2006 and later years. A significant number of devices were found to be manufactured out of their specifications. This was confirmed with analysis of the wider data set from the NRR. This device was found to have an unacceptably high revision rate. Bilateral prostheses, those implanted into female patients and devices implanted in later years were found to be at greater risk. A significant number of explanted components were found to be manufactured with bearing diameters outside of the manufacturer's stated tolerances. Our findings highlight the clinical importance of hitherto unrecognised variations in device production. Published by the BMJ Publishing Group Limited. For permission to use (where not

  17. Is there any range-of-motion advantage to using bearings larger than 36mm in primary hip arthroplasty: A case-control study comparing 36-mm and large-diameter heads.

    Science.gov (United States)

    Delay, C; Putman, S; Dereudre, G; Girard, J; Lancelier-Bariatinsky, V; Drumez, E; Migaud, H

    2016-10-01

    Large-diameter (>36mm) total hip arthroplasty (THA) has developed rapidly since the advent of ceramic-on-ceramic (CoC) bearings and highly cross-linked polyethylene. Theoretically, the increase in diameter reduces the risk of instability, although the advantage of calibers beyond 36mm has not been demonstrated in terms of range-of-motion recovery. We conducted a comparative study with a single prosthesis model to determine whether increasing the caliber beyond 36mm provides: (1) better recovery of range-of-motion, (2) a higher functional score, and (3) reduction of the dislocation rate. Increasing the range-of-motion by increasing the caliber beyond 36mm provides better range-of-motion. We analyzed two consecutive, single-operator cementless THA series performed via the mini posterior approach, which differed only in the bearing system (51 metal-on-metal [MoM] with a mean caliber of 45mm±3.3 [range, 40-54] and 61 CoC with a 36-mm caliber). Both series were comparable preoperatively in terms of age, diagnosis, functional scores, preoperative range-of-motion, body mass index, UCLA activity level, and Charnley score. We compared the joint range of movement at follow-up and the gains in range of movement, onset of dislocation, and functional scores (Oxford, Postel-Merle d'Aubigné [PMA]). The mean overall joint range-of-motion was 254°±39° (range, 150-310°) for an 81°±44° (range, -50 to 180°) gain in the MoM group and 256°±23° (range, 200-280°) for an 84°±40° (range, 0-160°) gain in the CoC group (NS). The MoM group presented the following results: Oxford=13.71±3.66 (range, 12-33) for a gain of 24.82 points±7.9 (range, -1 to 40), PMA=17.75±1.06 (range, 11-18) for a gain of 7.78 points±4.01 (range, 2-15). The CoC group had: Oxford=14.98±4.42 (range, 12-36) for a gain of 24.75 points±6.55 (range, 12-40), PMA 17.66±0.7 (range, 14-18) for a gain of 8 points±3.77 (range, 1-15). None of the gains and scores at follow-up differed significantly between

  18. Adaptive bone remodeling around cementless femoral stems with two different designs: fitmore and Alloclassic

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    M. P. Karagodina

    2015-01-01

    Full Text Available Introduction. We hypothesized that a short stem preserves periprosthetic bone mass in the proximal femur after total hip arthroplasty (THA. We performed a comparative analysis of clinical efficiency and X-ray results of the BMD around two cementless femoral stems with two different designs. Purpose. To compare the clinical and radiographic results of the study of adaptive bone remodeling in the proximal femur in patients after implantation of the femoral component and Alloclassic Fitmore Material and methods. We evaluated two groups of patients (mean age 58,3: 26 patients with a short femoral stem Fitmore (Zimmer and 20 patients with a standard stem Alloclassic (Zimmer. Clinical assessment of the hip condition was made according to Harris scale, supplemented by the evaluation of the pain level for femur by a visual analog scale at three levels. The radiological result was studied according to radiogrammetry and dual-energy X-ray absorptiometry (DXA. Results. Independently from design of the femoral component in both groups of patients was observed a significant clinical improvement. The BMD on the surgery side was measured using of analysis in Gruen zones. The first postoperative measurement was performed after surgery and further in 3, 6 and 12 months. DXA after 3 mo showed progressive loss BMD in all Gruen zones, but more significant in Gruen zones 2, 7 for Fitmore stem group, in Gruen zones 6, 7 for Alloclasic stem group. At 6 mo after THA in all Gruen zones of Fitmore vs Alloclasic femoral stems there were the phase of moderate stabilization. At 12 mo we observed decreased periprosthetic BMD in Gruen zone 1 and 7, however that there are no clinically relevant changes around two different designs of cementless femoral stems. Discussion. It isn’t dependent on design of a metal stem we showed progressive remodeling periprosthetic BMD in the proximal parts of hip (Gruen zone 1, 7 and we observed а slighter hypertrophy in the distal parts of

  19. [The incidence of osteopenia and osteoporosis in patients with cementless total hip arthroplasty].

    Science.gov (United States)

    Lacko, M; Schreierová, D; Čellár, R; Vaško, G

    2015-01-01

    The aim of the study was to evaluate the incidence of osteopenia and osteoporosis in the patients elected to cementless total hip replacement. The group evaluated comprised 100 patients with primary or secondary forms of coxarthrosis who underwent cementless total hip arthroplasty (THA). The results of densitometric examination of the lumbar spine and proximal femur were analysed. Based on the lowest T-score value, the patients were divided into three groups, i.e., fist, normal bone density; second, osteopenia; third, osteoporosis. Clinical examination included patient medical history, Harris hip scores and visual analogue scale assessment for pain intensity; the Kellgren-Lawrence classification was used to measure the grade of hip osteoarthritis; blood tests were made to assess the levels of total calcium, ionised calcium, phosphorus, vitamin D and the markers of bone resorption and formation. Osteoporosis was found in 32 and osteopenia in 21 patients; 47 patients had normal bone density. Osteoporosis was detected in the lumbar spine of 21 patients, in the proximal femur of nine patients and at both sites in two patients. In 13 patients this diagnosis was made for the fist time. The patients with osteoporosis had a significantly lower body mass index. There were no differences in the other characteristics, i.e., age, functional, radiological and laboratory findings, among the groups; all three showed the mean vitamin D concentration below the lowest level of its physiological range. Insufficient vitamin D levels were found in 54 women and 18 men. Of all patients, only 13 women and four men took vitamin D supplements. DISCUSSION Osteoarthritis and osteoporosis are the most frequent complex musculoskeletal diseases. Several studies have suggested that these disorders are mutually exclusive. This assumption has been based on the absence of radiographic evidence of osteoarthritis seen in many elderly patients with femoral neck fractures. Our relatively frequent

  20. Acceleration of Intended Pozzolanic Reaction under Initial Thermal Treatment for Developing Cementless Fly Ash Based Mortar

    Directory of Open Access Journals (Sweden)

    Yang-Hee Kwon

    2017-02-01

    Full Text Available Without using strong alkaline solution or ordinary Portland cement, a new structural binder consisting of fly ash and hydrated lime was hardened through an intensified pozzolanic reaction. The main experimental variables are the addition of silica fume and initial thermal treatment (60 °C for 3 days. A series of experiments consisting of mechanical testing (compressive and flexural strength, modulus of elasticity, X-ray diffraction, and measurements of the heat of hydration, pore structure, and shrinkage were conducted. These tests show that this new fly ash-based mortar has a compressive strength of 15 MPa at 91 days without any silica fume addition or initial thermal treatment. The strength increased to over 50 MPa based on the acceleration of the intensified pozzolanic reaction from the silica fume addition and initial thermal treatment. This is explained by a significant synergistic effect induced by the silica fume. It intensifies the pozzolanic reaction under thermal treatment and provides a space filling effect. This improved material performance can open a new pathway to utilize the industrial by-product of fly ash in cementless construction materials.

  1. Fabrication of low-cost, cementless femoral stem 316L stainless steel using investment casting technique.

    Science.gov (United States)

    Baharuddin, Mohd Yusof; Salleh, Sh-Hussain; Suhasril, Andril Arafat; Zulkifly, Ahmad Hafiz; Lee, Muhammad Hisyam; Omar, Mohd Afian; Abd Kader, Ab Saman; Mohd Noor, Alias; A Harris, Arief Ruhullah; Abdul Majid, Norazman

    2014-07-01

    Total hip arthroplasty is a flourishing orthopedic surgery, generating billions of dollars of revenue. The cost associated with the fabrication of implants has been increasing year by year, and this phenomenon has burdened the patient with extra charges. Consequently, this study will focus on designing an accurate implant via implementing the reverse engineering of three-dimensional morphological study based on a particular population. By using finite element analysis, this study will assist to predict the outcome and could become a useful tool for preclinical testing of newly designed implants. A prototype is then fabricated using 316L stainless steel by applying investment casting techniques that reduce manufacturing cost without jeopardizing implant quality. The finite element analysis showed that the maximum von Mises stress was 66.88 MPa proximally with a safety factor of 2.39 against endosteal fracture, and micromotion was 4.73 μm, which promotes osseointegration. This method offers a fabrication process of cementless femoral stems with lower cost, subsequently helping patients, particularly those from nondeveloped countries. Copyright © 2013 International Center for Artificial Organs and Transplantation and Wiley Periodicals, Inc.

  2. Design optimization of cementless metal-backed cup prostheses using the concept of functionally graded material

    Energy Technology Data Exchange (ETDEWEB)

    Hedia, H S; El-Midany, T T; Shabara, M A N; Fouda, N [Production Engineering and M/C Design Department, Faculty of Engineering, Mansoura University, Mansoura (Egypt)

    2006-09-15

    Metal backing has been widely used in acetabular cup design. A stiff backing for a polyethylene liner was initially believed to be mechanically favourable. Yet, recent studies of the load transfer around acetabular cups have shown that a stiff backing causes two problems. It generates higher stress peaks around the acetabular rim than those caused by full polyethylene cups and reduces the stresses transferred to the dome of the acetabulum causing stress shielding. The aim of this study is to overcome these two problems by improving the design of cementless metal-backed acetabular cups using the two-dimensional functionally graded material (FGM) concept through finite-element analysis and optimization techniques. It is found that the optimal 2D FGM model must have three bioactive materials of hydroxyapatite, Bioglass and collagen. This optimal material reduces the stress shielding at the dome of the acetabulum by 40% and 37% compared with stainless steel and titanium metal backing shells, respectively. In addition, using the 2D FGM model reduces the maximum interface shear stress in the bone by 31% compared to the titanium metal backing shell.

  3. Acceleration of Intended Pozzolanic Reaction under Initial Thermal Treatment for Developing Cementless Fly Ash Based Mortar.

    Science.gov (United States)

    Kwon, Yang-Hee; Kang, Sung-Hoon; Hong, Sung-Gul; Moon, Juhyuk

    2017-02-24

    Without using strong alkaline solution or ordinary Portland cement, a new structural binder consisting of fly ash and hydrated lime was hardened through an intensified pozzolanic reaction. The main experimental variables are the addition of silica fume and initial thermal treatment (60 °C for 3 days). A series of experiments consisting of mechanical testing (compressive and flexural strength, modulus of elasticity), X-ray diffraction, and measurements of the heat of hydration, pore structure, and shrinkage were conducted. These tests show that this new fly ash-based mortar has a compressive strength of 15 MPa at 91 days without any silica fume addition or initial thermal treatment. The strength increased to over 50 MPa based on the acceleration of the intensified pozzolanic reaction from the silica fume addition and initial thermal treatment. This is explained by a significant synergistic effect induced by the silica fume. It intensifies the pozzolanic reaction under thermal treatment and provides a space filling effect. This improved material performance can open a new pathway to utilize the industrial by-product of fly ash in cementless construction materials.

  4. A finite element analysis of the vibration behaviour of a cementless hip system.

    Science.gov (United States)

    Pérez, M A; Seral-García, B

    2013-01-01

    An early diagnosis of aseptic loosening of a total hip replacement (THR) by plain radiography, scintigraphy or arthography has been shown to be less reliable than using a vibration technique. However, it has been suggested that it may be possible to distinguish between a secure and a loose prosthesis using a vibration technique. In fact, vibration analysis methods have been successfully used to assess dental implant stability, to monitor fracture healing and to measure bone mechanical properties. Several studies have combined the vibration technique with the finite element (FE) method in order to better understand the events involved in the experimental technique. In the present study, the main goal is to simulate the change in the resonance frequency during the osseointegration process of a cementless THR (Zweymüller). The FE method was used and a numerical modal analysis was conducted to obtain the natural frequencies and mode shapes under vibration. The effects were studied of different bone and stem material properties, and different contact conditions at the bone-implant interface. The results were in agreement with previous experimental and computational observations, and differences among the different cases studied were detected. As the osseointegration process at the bone-implant interface evolved, the resonance frequency values of the femur-prosthesis system also increased. In summary, vibration analysis combined with the FE method was able to detect different boundary conditions at the bone-implant interface in cases of both osseointegration and loosening.

  5. Primary Stability Recognition of the Newly Designed Cementless Femoral Stem Using Digital Signal Processing

    Directory of Open Access Journals (Sweden)

    Mohd Yusof Baharuddin

    2014-01-01

    Full Text Available Stress shielding and micromotion are two major issues which determine the success of newly designed cementless femoral stems. The correlation of experimental validation with finite element analysis (FEA is commonly used to evaluate the stress distribution and fixation stability of the stem within the femoral canal. This paper focused on the applications of feature extraction and pattern recognition using support vector machine (SVM to determine the primary stability of the implant. We measured strain with triaxial rosette at the metaphyseal region and micromotion with linear variable direct transducer proximally and distally using composite femora. The root mean squares technique is used to feed the classifier which provides maximum likelihood estimation of amplitude, and radial basis function is used as the kernel parameter which mapped the datasets into separable hyperplanes. The results showed 100% pattern recognition accuracy using SVM for both strain and micromotion. This indicates that DSP could be applied in determining the femoral stem primary stability with high pattern recognition accuracy in biomechanical testing.

  6. Design process of cementless femoral stem using a nonlinear three dimensional finite element analysis.

    Science.gov (United States)

    Baharuddin, Mohd Yusof; Salleh, Sh-Hussain; Zulkifly, Ahmad Hafiz; Lee, Muhammad Hisyam; Noor, Alias Mohd; A Harris, Arief Ruhullah; Majid, Norazman Abdul; Abd Kader, Ab Saman

    2014-02-03

    Minimal available information concerning hip morphology is the motivation for several researchers to study the difference between Asian and Western populations. Current use of a universal hip stem of variable size is not the best option for all femur types. This present study proposed a new design process of the cementless femoral stem using a three dimensional model which provided more information and accurate analysis compared to conventional methods. This complete design cycle began with morphological analysis, followed by femoral stem design, fit and fill analysis, and nonlinear finite element analysis (FEA). Various femur parameters for periosteal and endosteal canal diameters are measured from the osteotomy level to 150 mm below to determine the isthmus position. The results showed better total fit (53.7%) and fill (76.7%) canal, with more load distributed proximally to prevent stress shielding at calcar region. The stem demonstrated lower displacement and micromotion (less than 40 μm) promoting osseointegration between the stem-bone and providing primary fixation stability. This new design process could be used as a preclinical assessment tool and will shorten the design cycle by identifying the major steps which must be taken while designing the femoral stem.

  7. Primary Stability Recognition of the Newly Designed Cementless Femoral Stem Using Digital Signal Processing

    Science.gov (United States)

    Salleh, Sh-Hussain; Hamedi, Mahyar; Zulkifly, Ahmad Hafiz; Lee, Muhammad Hisyam; Mohd Noor, Alias; Harris, Arief Ruhullah A.; Abdul Majid, Norazman

    2014-01-01

    Stress shielding and micromotion are two major issues which determine the success of newly designed cementless femoral stems. The correlation of experimental validation with finite element analysis (FEA) is commonly used to evaluate the stress distribution and fixation stability of the stem within the femoral canal. This paper focused on the applications of feature extraction and pattern recognition using support vector machine (SVM) to determine the primary stability of the implant. We measured strain with triaxial rosette at the metaphyseal region and micromotion with linear variable direct transducer proximally and distally using composite femora. The root mean squares technique is used to feed the classifier which provides maximum likelihood estimation of amplitude, and radial basis function is used as the kernel parameter which mapped the datasets into separable hyperplanes. The results showed 100% pattern recognition accuracy using SVM for both strain and micromotion. This indicates that DSP could be applied in determining the femoral stem primary stability with high pattern recognition accuracy in biomechanical testing. PMID:24800230

  8. Early results of the use of oblong S-ROM cementless acetabular component

    Directory of Open Access Journals (Sweden)

    Popović Zoran

    2003-01-01

    Full Text Available Massive deficiency of acetabular bone stock is a challenging problem in the increasing number of patients who need a revision of the failed hip arthroplasty. Oblong acetabular cup has been presented as an alternative reconstruction technique for hips with extensive acetabular bone loss. The aim of this study was to present our results with the use of a bilobed acetabular component inserted during revisional surgery, to define indications, and to introduce this method into our orthopaedic practice. Seven patients underwent revisional hip arthroplasty with a cementless oblong acetabular component between September 2000 and June 2002. Six patients underwent revisional hip arthroplasty, and in one primary hip arthroplasty by oblong acetabular component was performed because of bone defect of acetabulum after gunshot fracture. The average follow up was thirteen months. Radiographic analysis in all patients demonstrated stable bone incorporated acetabular component with the restored hip. All the patients walked with full weight bearing and were without pain. On the basis of our experience we find this method statisfactory in certain types of bone defefects of acetabulum, and that it provides stable reconstruction of acetabulum with the correction of hip joint.

  9. Primary stability recognition of the newly designed cementless femoral stem using digital signal processing.

    Science.gov (United States)

    Baharuddin, Mohd Yusof; Salleh, Sh-Hussain; Hamedi, Mahyar; Zulkifly, Ahmad Hafiz; Lee, Muhammad Hisyam; Mohd Noor, Alias; Harris, Arief Ruhullah A; Abdul Majid, Norazman

    2014-01-01

    Stress shielding and micromotion are two major issues which determine the success of newly designed cementless femoral stems. The correlation of experimental validation with finite element analysis (FEA) is commonly used to evaluate the stress distribution and fixation stability of the stem within the femoral canal. This paper focused on the applications of feature extraction and pattern recognition using support vector machine (SVM) to determine the primary stability of the implant. We measured strain with triaxial rosette at the metaphyseal region and micromotion with linear variable direct transducer proximally and distally using composite femora. The root mean squares technique is used to feed the classifier which provides maximum likelihood estimation of amplitude, and radial basis function is used as the kernel parameter which mapped the datasets into separable hyperplanes. The results showed 100% pattern recognition accuracy using SVM for both strain and micromotion. This indicates that DSP could be applied in determining the femoral stem primary stability with high pattern recognition accuracy in biomechanical testing.

  10. Damage Patterns at the Head-Stem Taper Junction Helps Understand the Mechanisms of Material Loss.

    Science.gov (United States)

    Hothi, Harry S; Panagiotopoulos, Andreas C; Whittaker, Robert K; Bills, Paul J; McMillan, Rebecca A; Skinner, John A; Hart, Alister J

    2017-01-01

    Material loss at the taper junction of metal-on-metal total hip arthroplasties has been implicated in their early failure. The mechanisms of material loss are not fully understood; analysis of the patterns of damage at the taper can help us better understand why material loss occurs at this junction. We mapped the patterns of material loss in a series of 155 metal-on-metal total hip arthroplasties received at our center by scanning the taper surface using a roundness-measuring machine. We examined these material loss maps to develop a 5-tier classification system based on visual differences between different patterns. We correlated these patterns to surgical, implant, and patient factors known to be important for head-stem taper damage. We found that 63 implants had "minimal damage" at the taper (material loss material loss. We found that (1) head diameter and (2) time to revision were key significant variables separating the groups. These material loss maps allow us to suggest different mechanisms that dominate the cause of the material loss in each pattern: (1) corrosion, (2) mechanically assisted corrosion, or (3) intraoperative damage or poor size tolerances leading to toggling of trunnion in taper. Copyright © 2016 Elsevier Inc. All rights reserved.

  11. A gentamicin-releasing coating for cementless hip prostheses - Longitudinal evaluation of efficacy using in vitro bio-optical imaging and its wide-spectrum antibacterial efficacy

    NARCIS (Netherlands)

    Neut, Danielle; Dijkstra, Rene J. B.; Thompson, Jonathan I.; van der Mei, Henny C.; Busscher, Henk J.

    2012-01-01

    Cementless prostheses are increasingly popular in total hip arthroplasties. Therewith, common prophylactic measures to reduce the risk of postoperative infection like the use of antibiotic-loaded bone cements, will no longer be available. Alternative prophylactic measures may include the use of

  12. Development of an acoustic measurement protocol to monitor acetabular implant fixation in cementless total hip Arthroplasty: A preliminary study.

    Science.gov (United States)

    Goossens, Quentin; Leuridan, Steven; Henyš, Petr; Roosen, Jorg; Pastrav, Leonard; Mulier, Michiel; Desmet, Wim; Denis, Kathleen; Vander Sloten, Jos

    2017-11-01

    In cementless total hip arthroplasty (THA), the initial stability is obtained by press-fitting the implant in the bone to allow osseointegration for a long term secondary stability. However, finding the insertion endpoint that corresponds to a proper initial stability is currently based on the tactile and auditory experiences of the orthopedic surgeon, which can be challenging. This study presents a novel real-time method based on acoustic signals to monitor the acetabular implant fixation in cementless total hip arthroplasty. Twelve acoustic in vitro experiments were performed on three types of bone models; a simple bone block model, an artificial pelvic model and a cadaveric model. A custom made beam was screwed onto the implant which functioned as a sound enhancer and insertor. At each insertion step an acoustic measurement was performed. A significant acoustic resonance frequency shift was observed during the insertion process for the different bone models; 250 Hz (35%, second bending mode) to 180 Hz (13%, fourth bending mode) for the artificial bone block models and 120 Hz (11%, eighth bending mode) for the artificial pelvis model. No significant frequency shift was observed during the cadaveric experiment due to a lack of implant fixation in this model. This novel diagnostic method shows the potential of using acoustic signals to monitor the implant seating during insertion. Copyright © 2017 IPEM. Published by Elsevier Ltd. All rights reserved.

  13. Mandibular reconstruction with a bioactive-coated cementless Ti6Al4V modular endoprosthesis in Macaca fascicularis.

    Science.gov (United States)

    Chanchareonsook, N; Tideman, H; Lee, S; Hollister, S J; Flanagan, C; Jansen, J A

    2014-06-01

    The titanium mandibular modular endoprosthesis fixed with polymethylmethacrylate cement in the medullary space of the mandible has been introduced in previous studies. However, the internal parts of these devices have been found to be prone to loosening and wound dehiscence. The current study introduces a newly designed bioactive-coated cementless modular mandibular endoprosthesis, which was used for reconstruction in Macaca fascicularis. The devices were coated with hydroxyapatite (HA) and hydroxyapatite/bioglass (HA/BG) and implanted in unilateral mandibular segmental defects in nine monkeys for 6 months. Biomechanical testing found the reconstructed mandible to have a mean stiffness value of 110.43 N/mm. Histologically, there were both fibrous capsule and woven bone around the device body, and histomorphology analysis showed 64.17% bone contact to device stem surface. The percentage bone volume calculated from micro-computed tomography analysis around the stem surface was found to be superior to that reported in previous studies of cemented mandibular endoprostheses. Intermodular connection screw loosening has also been resolved with the dovetail interconnection. In conclusion, the current bioactive-coated cementless mandibular endoprosthesis is feasible for use in mandibular segmental reconstruction. However, insufficient load-bearing capability and a high rate of intraoral wound dehiscence were found in the majority of the study animals. Further device modifications and improvements in the surgical technique need to be addressed in future studies. Copyright © 2014 International Association of Oral and Maxillofacial Surgeons. All rights reserved.

  14. Mechanical evaluation of adjunctive fixation for prevention of periprosthetic femur fracture with the Zurich cementless total hip prosthesis.

    Science.gov (United States)

    Pozzi, Antonio; Peck, Jeffrey N; Chao, Peini; Choate, Christina J; Barousse, Dan; Conrad, Bryan

    2013-06-01

    To evaluate whether cerclage wire or a lateral plate increases the peak-torque load to failure, compared to femora without adjunctive fixation, in femora implanted with Zurich Cementless stems. In vitro biomechanical study. Paired femora from adult dogs (n = 24) weighing 28-35 kg. Pairs of femora were implanted with a stem and randomly assigned to 2 treatment groups: cerclage or plate. Within each pair, either 3 loop cerclage wires or a laterally applied 12-hole Advanced Locking Plate System 10-mm plate (ALPS 10) were implanted in a femur, whereas the contralateral femur acted as control with no adjunctive fixation. After application of a static axial load each specimen was loaded to failure in torsion. Peak torque load at failure was compared between femora with each adjunctive fixation and the control using a paired t-test; P plated group (P plates and with cerclage were 13.9% and 7.2% stronger in torsion than the femora without fixation, respectively. Adjunctive fixation with a laterally applied ALPS 10 may aid in the prevention of peri-prosthetic fractures associated with Zurich Cementless medium stems. © Copyright 2013 by The American College of Veterinary Surgeons.

  15. Does the Risk of Rerevision Vary Between Porous Tantalum Cups and Other Cementless Designs After Revision Hip Arthroplasty?

    DEFF Research Database (Denmark)

    Laaksonen, Inari; Lorimer, Michelle; Gromov, Kirill

    2017-01-01

    BACKGROUND: Earlier results with porous tantalum acetabular cups in revision THA generally have been favorable. Recently there has been some evidence presented that porous tantalum cups might decrease the risk of rerevision in the setting of revision hip surgery performed owing to prosthetic joint...... infection (PJI). As the data supporting this assertion come from a study with a limited study population, examining this issue with a large registry approach may be enlightening. QUESTIONS/PURPOSES: By combining results from two large, national registries, we asked: (1) Do porous tantalum cups show improved...... survival after revision THA compared with other cementless designs? (2) Does the use of porous tantalum cups influence survivorship when rerevision for PJI is the endpoint? METHODS: A total of 2442 first-time THA revisions with porous tantalum cups and 4401 first-time revisions with other uncemented cups...

  16. Delayed cementless total hip arthroplasty for neglected dislocation of hip combined with complex acetabular fracture and deficient bone stock

    Directory of Open Access Journals (Sweden)

    Gavaskar Ashok S

    2012-12-01

    Full Text Available 【Abstract】Total hip arthroplasty (THA for an un-treated acetabular fracture is technically challenging and the long-term result is not so favorable. A 45-year-old fe-male patient with untreated column and comminuted poste-rior wall fracture of the acetabulum was treated in our insti-tution by reconstruction of the posterior wall using iliac strut autograft and plate stabilization of the posterior col-umn with cancellous grafting and cementless THA in a single stage. At 3 years’ follow-up, the patient was independently mobile without limb length discrepancy. Radiological evalu-ation showed well integrated components and bone grafts. No evidence of aseptic loosening or osteolysis was found. This report aims to emphasize that bony acetabular recon-struction allows the use of primary hip components, which improves prosthesis longevity and preserves bone stock for a future revision. Key words: Acetabulum; Fractures, bone; Hip dislocation; Arthroplasty, replacement, hip

  17. Delivery of Antibiotics from Cementless Titanium-Alloy Cubes May Be a Novel Way to Control Postoperative Infections

    Science.gov (United States)

    Bezuidenhout, Martin B.; van Staden, Anton D.; Oosthuizen, Gert A.; Dimitrov, Dimitar M.; Dicks, Leon M. T.

    2015-01-01

    Bacterial colonisation and biofilm formation onto orthopaedic devices are difficult to eradicate. In most cases infection is treated by surgical removal of the implant and cleaning of the infected area, followed by extensive treatment with broad-spectrum antibiotics. Such treatment causes great discomfort, is expensive, and is not always successful. In this study we report on the release of vancomycin through polyethersulfone membranes from channels in cementless titanium-alloy cubes. The cubes were constructed with LaserCUSING from Ti6Al4V ELI powder. Vancomycin was released by non-Fickian anomalous (constraint) diffusion. Approximately 50% of the vancomycin was released within the first 17 h. However, sustained delivery of vancomycin for 100 h was possible by reinjecting the channels. Refillable implants may be a novel way to control postoperative infections. PMID:25861649

  18. The thrust plate prosthesis in patients with aseptic osteonecrosis of the femoral head.

    Science.gov (United States)

    Fink, Bernd; Schneider, Thomas; Conrad, Silke; Jaeger, Marcus; Protzen, Michael; Rüther, Wolfgang

    2002-12-01

    The thrust plate prosthesis (TPP) is an implant with a metaphyseal fixation at the proximal femur that transmits the load forces of the hip onto the femoral neck. The osseous incorporation of the TPP and the adaptation of the bone to this force transmission depend on the bone quality, which is reduced to minor vitality and stability in patients with osteonecrosis of the femoral head. Depending on the etiology of the femoral head necrosis, the TPP might lead to early failures. In a prospective study, 63 patients with 72 cementless TPP due to femoral head osteonecrosis were examined. A clinical and radiological evaluation was performed preoperatively, 3 and 6 months postoperatively, and every year thereafter. The average follow-up period was 4.8+/-1.3 years with a minimum of 3 years. The pathogenesis of femoral head necrosis included alcoholism (n=19), subsequent to renal transplantation (n=11), during cortisone therapy of other dyscrasia (n=9), preceding a polychemotherapy (n=4), diabetes (n=3), sickle cell anemia (n=1), and idiopathic osteonecrosis (n=25). The Harris Hip Score increased continuously from 50.0 points beyond 79.8 points after 3 months to 86.8 points within the 1st year, and subsequently remained stable at this level. Revision was necessary in six cases (8.3%). Of these, three had an aseptic loosening of the implant: 2 cases with renal transplantation and 1 of alcoholism with an extension of the necrotic area to the seating of the TPP. The other three patients showed septic implant loosenings: 2 cases with renal transplantation and 1 of alcoholism. Radiolucent lines were found in 9 cases (12.5%), mostly in zones 1 and 2 underneath the TPP. Of these, 1 with an idiopathic osteonecrosis was assessed to be radiologically loosened. The overall failure rate was 9.7%, with a proportion of 36.4% in patients with renal transplantation. Excluding this specific patient group, the failure rate was 4.9%. Femoral head necrosis following renal transplantation and

  19. Quality of intertrochanteric cancellous bone as predictor of femoral stem RSA migration in cementless total hip arthroplasty.

    Science.gov (United States)

    Moritz, Niko; Alm, Jessica J; Lankinen, Petteri; Mäkinen, Tatu J; Mattila, Kimmo; Aro, Hannu T

    2011-01-11

    In cementless total hip arthroplasty, osteoporosis may jeopardize the achievement of immediate stability and lead to migration of anatomically shaped femoral stems. Poor quality of proximal cancellous bone per se may also affect the rate of osseointegration. In a selected group of female total hip arthroplasty patients (mean age 64 years) with unremarkable medical history, intertrochanteric cancellous bone biopsy was taken from the site of stem implantation. Local bone quality, determined by structural μCT imaging and destructive compression testing of the biopsy tissue, was used as the predictor of three-dimensional stem migration determined by radiostereometric analysis (RSA) up to 24 months. The patients exhibited major differences in mechanical properties of the intertrochanteric cancellous bone, which were closely related to the structural parameters calculated from μCT data. Unexpectedly, the major differences observed in the quality of trochanteric cancellous bone had only minor reflections in the RSA migration of the femoral stems. In statistical analysis, the μCT-based bone mineral density quartile (low, middle, high) was the only significant predictor for stem translation at 24 months (p=0.022) but only a small portion (R(2)=0.16) of the difference in translation could be explained by changes in bone mineral density quartile. None of the other parameters investigated predicted stem migration in translation or rotation. In conclusion, poor quality of intertrochanteric cancellous bone seems to contribute to the risk of implant migration less than expected. Probably also the importance of surgical preservation of intertrochanteric cancellous bone has been over-emphasized for osseointegration of cementless stem. Copyright © 2010 Elsevier Ltd. All rights reserved.

  20. Risk factors for post-operative periprosthetic fractures following primary total hip arthroplasty with a proximally coated double-tapered cementless femoral component

    DEFF Research Database (Denmark)

    Gromov, K; Bersang, A; Nielsen, C S

    2017-01-01

    AIMS: The aim of this study was to identify patient- and surgery-related risk factors for sustaining an early periprosthetic fracture following primary total hip arthroplasty (THA) performed using a double-tapered cementless femoral component (Bi-Metric femoral stem; Biomet Inc., Warsaw, Indiana...... ratio were recorded post-operatively. Periprosthetic fractures were identified and classified according to the Vancouver classification. Regression analysis was performed to identify risk factors for early periprosthetic fracture. RESULTS: The mean follow-up was 713 days (1 to 2058). A total of 48...... significant two times increased risk over time for post-operative fracture. CONCLUSION: Dorr type C is an independent risk factor for early periprosthetic fracture, following THA using a double tapered cementless stem such as the Bi-Metric. Surgeons should take bone morphology into consideration when planning...

  1. Efficacy and safety of the topical application of tranexamic acid in primary cementless hip arthroplasty: prospective, randomised, double-blind and controlled study.

    Science.gov (United States)

    Tavares Sánchez-Monge, F J; Aguado Maestro, I; Bañuelos Díaz, A; Martín Ferrero, M Á; García Alonso, M F

    2017-11-08

    To evaluate the efficacy of topical tranexamic acid topical in cementless total hip arthroplasty from the point of view of bleeding, transfusion requirements and length of stay, and describe the complications of use compared to a control group. A prospective, randomised, double-blinded and controlled study including all patients undergoing cementless total hip arthroplasty in our centre between June 2014 and July 2015. Blood loss was estimated using the formula described by Nadler and Good. The final analysis included 119 patients. The decrease in haemoglobin after surgery was lower in the tranexamic acid group (3.28±1.13g/dL) than in the controls (4.03±1.27g/dL, P=.001) and estimated blood loss (1,216.75±410.46mL vs. 1,542.12±498.97mL, P<.001), the percentage of transfused patients (35.9% vs. 19.3%, P<.05) and the number of transfused red blood cell units per patient (0.37±0.77 vs. 0.98±1.77; P<.05). There were no differences between groups in the occurrence of complications or length of stay. The use of topical tranexamic acid in cementless total hip arthroplasty results in a decrease in bleeding and transfusion requirements without increasing the incidence of complications. Copyright © 2017 SECOT. Publicado por Elsevier España, S.L.U. All rights reserved.

  2. The value of bone scintigraphy in patients with pain in the thigh following cementless hip endoprosthesis. Aussagefaehigkeit der Skelettszintigraphie bei Oberschenkelschmerz nach zementlosem Hueftgelenkersatz

    Energy Technology Data Exchange (ETDEWEB)

    Ehrenheim, C. (Medizinische Hochschule Hannover (Germany). Abt. Nuklearmedizin und Spezielle Biophysik); Steinmetz, M.; Pohlemann, T. (Medizinische Hochschule Hannover (Germany). Unfallchirurgische Klinik); Tscherne, H. (Medizinische Hochschule Hannover (Germany). Unfallchirurgische Klinik)

    1993-04-01

    Persisting postoperative pain of the thigh is a common problem of cementless hip endoprostheses occurring in about 15-20% of the patients. We performed a comparative study including patients with (n=40) and without (n=45) pain of the thigh. 85 cementless porous-coated anatomic (PCA) hip endoprostheses in 74 patients were examined. All patients underwent clinical examination including a standardized questionnaire, X-ray, and 3-phase bone scintigraphy. Slight or moderate [sup 99m]Tc-MDP uptake in the area of the greater and lesser trochanter as well as at the tip was a common finding in PCA prostheses in patients without pain and was not a sign of loosening of the hip. Radiologically, there was no difference between patients with and without pain. However, persisting pain of the thigh in patients with PCA prosthesis corresponded with an increased uptake at the tip and the medial and lateral femur, not being a sign of loosening even in this group. The special biomechanical conditions of cementless prostheses causing inhomogeneous intraosseous stress distrubution are supposed to be the reason for that. (orig.)

  3. Head Injuries

    Science.gov (United States)

    ... ATV) Safety Balance Disorders Knowing Your Child's Medical History First Aid: Falls First Aid: Head Injuries Preventing Children's Sports Injuries Getting Help: Know the Numbers Concussions Stay ...

  4. Thrust plate prosthesis for osteonecrosis of the femoral head: short-term results of 15 patients followed 2-6 years.

    Science.gov (United States)

    Karatosun, Vasfi; Gunal, Izge; Unver, Bayram; Gultekin, Alper

    2006-10-01

    The thrust plate prosthesis is an implant with a metaphyseal fixation at the proximal femur that transmits the load forces of the hip onto the femoral neck. In this prospective study, 15 patients (8 women, 7 men) with 19 cementless thrust plate prostheses because of femoral head necrosis were examined. A clinical and radiologic evaluation was performed preoperatively, at 3, 6, 12, 18, and 24 months postoperatively, and every year thereafter. The mean follow-up period was 44 (range, 24-72) months. The average age at the time of surgery was 49 (27-70) years. The pathogenesis of femoral head necrosis included alcoholism (6 joints of 3 cases), Gaucher disease (1 joint of 1 case), Sheehan syndrome (2 joints of 1 case), and idiopathic (10 joints of 10 cases). The Harris hip score increased from 53 (range, 15-71) to 97 (92-100) points on the final evaluation. Although mean preoperative hip flexion and abduction were 78 degrees (45 degrees -110 degrees ) and 24 degrees (10 degrees -45 degrees ), respectively, these increased to 114 degrees (75 degrees -125 degrees ) and 47 degrees (45 degrees -50 degrees ) 12 months after surgery and remained stable up to the latest follow-up. None of the patients displayed mechanical problems, and revision was not necessary in any case. The thrust plate prosthesis shows midterm results comparable to those of the cementless stemmed prosthesis and supplies advantages, especially for younger patients with femoral head necrosis, because of its metaphyseal bone-preserving fixation.

  5. Study of bone remodeling of two models of femoral cementless stems by means of DEXA and finite elements

    Directory of Open Access Journals (Sweden)

    López-Prats Fernando

    2010-05-01

    Full Text Available Abstract Background A hip replacement with a cemented or cementless femoral stem produces an effect on the bone called adaptive remodelling, attributable to mechanical and biological factors. All of the cementless prostheses designs try to achieve an optimal load transfer in order to avoid stress-shielding, which produces an osteopenia. Long-term densitometric studies taken after implanting ABG-I and ABG-II stems confirm that the changes made to the design and alloy of the ABG-II stem help produce less proximal atrophy of the femur. The simulation with FE allowed us to study the biomechanical behaviour of two stems. The aim of this study was, if possible, to correlate the biological and mechanical findings. Methods Both models with prostheses ABG-I and II have been simulated in five different moments of time which coincide with the DEXA measurements: postoperative, 6 months, 1, 3 and 5 years, in addition to the healthy femur as the initial reference. For the complete comparative analysis of both stems, all of the possible combinations of bone mass (group I and group II of pacients in two controlled studies for ABG-I and II stems, respectively, prosthetic geometry (ABG-I and ABG-II and stem material (Wrought Titanium or TMZF were simulated. Results and Discussion In both groups of bone mass an increase of stress in the area of the cancellous bone is produced, which coincides with the end of the HA coating, as a consequence of the bottleneck effect which is produced in the transmission of loads, and corresponds to Gruen zones 2 and 6, where no osteopenia can be seen in contrast to zones 1 and 7. Conclusions In this study it is shown that the ABG-II stem is more effective than the ABG-I given that it generates higher tensional values on the bone, due to which proximal bone atrophy diminishes. This biomechanical behaviour with an improved transmission of loads confirmed by means of FE simulation corresponds to the biological findings obtained with

  6. Head Lice

    Science.gov (United States)

    ... 1044-1047. Canyon, DV, Speare R, et al . “Spatial and kinetic factors for the transfer of head ... for children. Natural products can give parents false sense of safety If using a natural product or ...

  7. Radiographic fit and fill analysis of a new second-generation proximally coated cementless stem compared to its predicate design.

    Science.gov (United States)

    Issa, Kimona; Pivec, Robert; Wuestemann, Thies; Tatevossian, Tiffany; Nevelos, Jim; Mont, Michael A

    2014-01-01

    The purpose of this study was to compare in vivo fit and fill analysis of a new second-generation proximally coated cementless stem compared to its predicate design. This prospective trial of 100 total hip arthroplasties compared specific radiographic "Fit and Fill" parameters between the two designs. Fit type was assessed by comparing the type of canal fill. Post-operative fill parameters such as mean stem-to-canal ratios and mean minimum and maximum gaps between the stems to the cortical bone in different sections and areas were compared. A significantly higher proportion of the second-generation stems had Type I fit (82% vs. 54%), had better stem to canal fill ratio in the middle (90.6% vs. 85.3%) and distal sections (88.1% vs. 78.6%) compared to the older design. The new second-generation stem design had a significantly better canal fit and distal canal fill in the medial and lateral portions. Copyright © 2014 Elsevier Inc. All rights reserved.

  8. The effects of pulsed low frequency magnetic field in early rehabilitation of patients with cementless total hip arthroplasty

    Directory of Open Access Journals (Sweden)

    Đurović Aleksandar

    2006-01-01

    Full Text Available Introduction: Early rehabilitation of patients with cementless total hip arthroplasty (cTHA includes different physical modalities and pulsed low frequency magnetic field (PLFMF, which effects have not been explored yet. Objective: To investigate the effects of PLFMF which was applied in different doses in early rehabilitation of patients with cTHA. Method: Prospective, controlled, clinical study included 90 patients, divided in three groups with 30 patients each. First two groups were treated with high (group A or low (group B doses of PLFMF, in addition to kinesitherapy. Control group C was treated only with kinesitherapy. Study was completed in three weeks. Results: Subjects of group A had significantly lower pain than group B (p<0.01 and group C (p<0.001 subjects in the first postoperative week. Pain in group B subjects was significantly lower than in group C in all three postoperative weeks (p<0.01. In relation to other two groups, subjects of group A had higher hip Harris score values at the end of the third postoperative week (p<0.05, and they were faster on 10-meter distance at the end of the first postoperative week (p<0.01. Conclusion: PLFMF used in low and high doses for patients with cTHA had significant effects on pain abatement, especially at higher doses. Improvement of function was earlier and more manifested in the group treated with high doses of PLFMF.

  9. Optimization of custom cementless stem using finite element analysis and elastic modulus distribution for reducing stress-shielding effect.

    Science.gov (United States)

    Saravana Kumar, Gurunathan; George, Subin Philip

    2017-02-01

    This work proposes a methodology involving stiffness optimization for subject-specific cementless hip implant design based on finite element analysis for reducing stress-shielding effect. To assess the change in the stress-strain state of the femur and the resulting stress-shielding effect due to insertion of the implant, a finite element analysis of the resected femur with implant assembly is carried out for a clinically relevant loading condition. Selecting the von Mises stress as the criterion for discriminating regions for elastic modulus difference, a stiffness minimization method was employed by varying the elastic modulus distribution in custom implant stem. The stiffness minimization problem is formulated as material distribution problem without explicitly penalizing partial volume elements. This formulation enables designs that could be fabricated using additive manufacturing to make porous implant with varying levels of porosity. Stress-shielding effect, measured as difference between the von Mises stress in the intact and implanted femur, decreased as the elastic modulus distribution is optimized.

  10. In Vivo Damage of the Head-Neck Junction in Hard-on-Hard Total Hip Replacements: Effect of Femoral Head Size, Metal Combination, and 12/14 Taper Design

    Directory of Open Access Journals (Sweden)

    Massimiliano Baleani

    2017-07-01

    Full Text Available Recently, concerns have been raised about the potential effect of head-neck junction damage products at the local and systemic levels. Factors that may affect this damage process have not been fully established yet. This study investigated the possible correlations among head-neck junction damage level, implant design, material combination, and patient characteristics. Head-neck junctions of 148 retrieved implants were analysed, including both ceramic-on-ceramic (N = 61 and metal-on-metal (N = 87 bearings. In all cases, the male taper was made of titanium alloy. Damage was evaluated using a four-point scoring system based on damage morphology and extension. Patient age at implantation, implantation time, damage risk factor, and serum ion concentration were considered as independent potential predicting variables. The damage risk factor summarises head-neck design characteristics and junction loading condition. Junction damage correlated with both implantation time and damage factor risk when the head was made of ceramic. A poor correlation was found when the head was made of cobalt alloy. The fretting-corrosion phenomenon seemed mainly mechanically regulated, at least when cobalt alloy components were not involved. When a component was made of cobalt alloy, the role of chemical phenomena increased, likely becoming, over implantation time, the damage driving phenomena of highly stressed junctions.

  11. Computer simulation of metal-on-metal epitaxy

    NARCIS (Netherlands)

    Breeman, M; Barkema, G.T.; Langelaar, M.H; Boerma, D.O

    1996-01-01

    Atom-embedding calculations and Monte Carlo simulations are presented on various topics which are important for a better understanding of homoepitaxial growth of metals. Results of realistic simulations of the homoepitaxial growth on Cu(100) are presented for the submonolayer regime as well as for

  12. Head Start.

    Science.gov (United States)

    Greenman, Geri

    2000-01-01

    Discusses an art project in which students created drawings of mop heads. Explains that the approach of drawing was more important than the subject. States that the students used the chiaroscuro technique, used by Rembrandt and Caravaggio, in which light appears out of the darkness. (CMK)

  13. Cementless, modular, distally fixed stem in hip revision arthroplasty: a single-center study of 132 consecutive hips.

    Science.gov (United States)

    Hashem, Ali; Al-Azzawi, Ammar; Riyadh, Hasan; Mukka, Sebastian; Sayed-Noor, Arkan

    2018-01-01

    The use of cementless, modular, distally fixed stem in hip revision arthroplasty has increased during the last decades. We aimed to analyze the early and late postoperative complications, re-operation rate, and survival rate of the MP stem operated at our county hospital with relatively limited caseload. In this retrospective study, we included 132 hips operated with MP stem between January 2007-2014. An independent observer reviewed patients' medical records in July 2015 (18-102 months postoperatively, median 52.5) to collect the following data: age, sex, American Society of Anesthesiologists (ASA) class, body mass index, indication of revision, type of operation, early and late complications, re-operation rate, and mortality during study period. The commonest indication for MP stem operation was aseptic loosening (72%). We found early and late postoperative complications in 29% of cases. The most common complication was prosthetic dislocation (8%), followed by intra-operative peri-prosthetic fracture (5%). The commonest indication for MP re-operation was soft tissue revision for infection (7%) followed by closed reduction for prosthetic dislocation (6%). We found no correlation between the age, sex, ASA class, and type of operation and the re-operation risk. Only one prosthesis was extracted giving a survival rate for 99% for the study period. This study showed good results of the MP prosthesis with reasonable complication and re-operation rates and negligible extraction rate, indicating the good performance of this implant even when used in the setting of a county hospital with limited caseload.

  14. Hip revision arthroplasty for failed osteosynthesis in periprosthetic Vancouver type B1 fractures using a cementless, modular, tapered revision stem.

    Science.gov (United States)

    Fink, B; Oremek, D

    2017-04-01

    To evaluate the hypothesis that failed osteosynthesis of periprosthetic Vancouver type B1 fractures can be treated successfully with stem revision using a transfemoral approach and a cementless, modular, tapered revision stem with reproducible rates of fracture healing, stability of the revision stem, and clinically good results. A total of 14 patients (11 women, three men) with a mean age of 72.4 years (65 to 90) undergoing revision hip arthroplasty after failed osteosynthesis of periprosthetic fractures of Vancouver type B1 were treated using a transfemoral approach to remove the well-fixed stem before insertion of a modular, fluted titanium stem which obtained distal fixation. These patients were clinically and radiologically followed up for a mean 52.2 months (24 to 144). After a mean of 15.5 weeks (standard deviation (sd) 5.7) all fractures had healed. No stems subsided and bony-ingrowth fixation had occurred according to the classification of Engh et al. The mean Harris Hip Score increased from a pre-operative score of 22.2 points (sd 9.7) to 81.5 points (sd 16.8) 24 months post-operatively. All hips had obtained an excellent result according to the classification of Beals and Tower. The technique described here for stem revision provides reproducibly good results in the treatment of failed osteosynthesis for Vancouver types B1 periprosthetic fractures of the hip. Cite this article: Bone Joint J 2017;99-B(4 Supple B):11-16. ©2017 Fink et al.

  15. Cementless femoral components in bicondylar hybrid knee arthroplasty in patients with rheumatoid arthritis: A 10-year survivorship analysis.

    Science.gov (United States)

    Hotfiel, Thilo; Carl, Hans-Dieter; Eibenberger, Teresa; Gelse, Kolja; Weiß, Julian; Jendrissek, Andreas; Swoboda, Bernd

    2017-01-01

    Total knee arthroplasty (TKA) has been established as a successful surgical treatment in the late stages of rheumatoid joint destruction. The purpose of this study was to review the clinical outcome and survivorship in rheumatoid arthritis (RA) patients undergoing TKA in hybrid technique with a cementless fixation of the femoral component. We analysed retrospectively 66 RA patients who underwent 72 TKAs (P.F.C. Sigma®). Mean follow-up time was 124 ± 41 months. To evaluate postoperative clinical outcome, knee injury and osteoarthritis outcome score (KOOS) and Oxford knee score (OKS) were assessed. Kaplan-Meier analysis was used to calculate survivorship. The primary outcome was revision for any reason. Thirty-four patients (36 knees) died and two patients (2 knees) were lost to follow-up. Three patients (four knees) did not agree to participate. Twenty-seven patients (30 knees) were available for assessing clinical scores. The average scores were 85 ± 14 for KOOS and 34 ± 10 for OKS. In three patients (three knees), revision was necessary, including restricted range of motion ( n = 1), instability ( n = 1), and infection ( n = 1). There were no cases of loosening in this cohort study. The survival rates were 100% at 5 years, 97.1% at 10 years (95% CI 89.0-99.2%) and 95.6% at 15 years (95% CI 86.9-98.5%). This study confirms that excellent clinical results and a good 10-year survivorship can be obtained with hybrid fixation technique in TKA in the unique population of RA patients.

  16. Intraoperative Femur Fracture Risk During Primary Direct Anterior Approach Cementless Total Hip Arthroplasty With and Without a Fracture Table.

    Science.gov (United States)

    Cohen, Eric M; Vaughn, Joshua J; Ritterman, Scott A; Eisenson, Daniel L; Rubin, Lee E

    2017-09-01

    There is no study to date comparing intraoperative femur fractures (IFFs) in the direct anterior approach (DAA) with and without a fracture table. We hypothesize that there is no significant difference in the IFF with and without a fracture table when performed by experienced DAA hip surgeons. This study is a 1-year retrospective review of patients who underwent DAA total hip arthroplasty by 2 surgeons: one surgeon uses a flat table and manually elevates the femur with a large bone hook, while the other surgeon uses a fracture table and a mechanical femoral elevator. Exclusion criteria included cemented femoral implants, femoral neck fractures, and lack of 6-month follow-up. We identified 487 patients for analysis (220 male and 267 female, average age 66.55 years). There were 12 total IFFs (2.46%): 8 female and 4 male patients. The average age of IFF patients was 70.67 years and in nonfracture patients was 66.00 years. There was no difference in gender (P = .2981) or age (P = .2099) between IFF and nonfracture patients. In the fracture table group, there were 6 IFFs (2.22%) in 271 patients; in the nonfracture table group, there were 6 IFFs (2.76%) in 216 patients. There was no statistical difference in IFF between the 2 groups (P = .6973). We observed just 2 patients (0.4%) in this series where the IFFs changed management requiring a revision femoral stem. There was no statistical difference in IFF with or without the use of fracture table. Both DAA surgical technique variations are felt to be equivalent regarding the risk for IFF during DAA cementless total hip arthroplasty. Copyright © 2017 Elsevier Inc. All rights reserved.

  17. [Cementless total hip arthroplasty after acute femoral neck fracture in active patients. Prospective matched study with a minimum follow-up of 5 years].

    Science.gov (United States)

    Lizaur-Utrilla, A; Sanz-Reig, J; Miralles-Muñoz, F A

    2014-01-01

    To evaluate outcomes of cementless total hip replacement after acute femoral neck fracture in active patients. A prospective matched study was conducted to compare the results between 76 patients with fractures and 76 patients with osteoarthritis. The Harris score, short-WOMAC and SF-12 were used for the clinical assessment. The mean follow-up was 7.3 years (range 5-11). There were no significant differences in medical or surgical complications between the 2 groups. Functional outcomes were similar, but more walking aids were used in fracture group. There were 6 revisions among the fractures group (one dislocation, 2 deep infections, 3 aseptic loosening), and 2 aseptic loosening among controls. There was no significant difference in arthroplasty survival at 10 years (88.7 vs. 96.1%, P=.15). The mortality rates at 2 and 10 years were similar. Cementless total hip replacement for treatment of acute femoral neck fracture showed similar results to those of elective surgery for osteoarthritis in these selected patients. Copyright © 2013 SECOT. Published by Elsevier Espana. All rights reserved.

  18. Functional and radiographic evaluation and quality of life analysis after cementless total hip arthroplasty with ceramic bearings: minimum of 5 years follow-up

    Directory of Open Access Journals (Sweden)

    Rafael Borghi Mortat

    2013-12-01

    Full Text Available Objective: The aim of the study is to analyze and correlate functional and radiographic results and quality of life in patients undergoing cementless total hip arthroplasty with ceramic surface, performed at Hospital Servidor Publico de Sao Paulo from 2001 to 2006. Methods: We retrospectively analyzed 35 hips treated with cementless total hip arthroplasty with ceramic surfaces with a minimum follow-up of 5 years. Functional evaluation was based on the Harris Hip Score (HHS. Radiographic evaluation was based on the method proposed by Charles Engh for evaluation of femoral osseointegration and on DeLee and Charnley zones for acetabulum. Quality of life was assessed by SF-36 questionnaire. Results: The HHS presented excellent and good results in 91% of patients postoperatively (mean of 93.14 points HHS. As for radiographic evaluation, we found excellent results in 100% of evaluated hips (proven osseointegration. SF-36 scores were not compared to the control group for the following components: pain, vitality, mental health and social aspects. The difference between HHS pre and postoperatively had a statistically significant correlation with physical functioning of the SF-36. Conclusion: Total hip arthroplasty with ceramic surface is a treatment that enables functional improvement of the hip and increases quality of life of patients to levels close to those of people without joint diseases.

  19. Monobloc implants in cementless total hip arthroplasty in patients with Legg-Calve-Perthes disease: a long-term follow-up.

    Science.gov (United States)

    Luo, Ze-Yu; Wang, Hao-Yang; Wang, Duan; Pan, Hui; Pei, Fu-Xing; Zhou, Zong-Ke

    2017-09-05

    The purpose of this study was to evaluate 10-year outcomes in cementless monobloc total hip arthroplasty (THA) in a group of hips with Legg-Calve-Perthes disease (LCPD). We reviewed 71 patients (88 hips) who underwent cementless THA with a diagnosis of LCPD from 2003 to 2009. From the total of 71 patients, 34 men and 37 women with an average age of 49.94 years were included. The mean follow-up period was 10 years. The mean Harris Hip Score improved significantly from 46.42 to 89.70. Similarly, the postoperative range of motion, hip dysfunction and osteoarthritis outcome score and SF-12 score also significantly improved. The mean leg lengthening was 22.1 mm. During the follow-up, eight complications were noted, including two cases of intraoperative femoral fractures, two cases of sciatic nerve paralysis, two cases of heterotrophic ossifications, one case of thigh pain and one case of dislocation. One revision was conducted for a periprosthetic fracture, and the survivorship at 10 years was 98.3%. These data suggest that the monobloc stem can lead to satisfactory outcomes for clinical function, radiological evaluation, restoration of the normal limb lengths, complications, and survivorship among LCPD patients undergoing total hip arthroplasty.

  20. Is HEADS in our heads?

    DEFF Research Database (Denmark)

    Boisen, Kirsten A; Hertz, Pernille Grarup; Blix, Charlotte

    2016-01-01

    BACKGROUND: Outpatient clinic visits are a window of opportunity to address health risk behaviors and promote a healthier lifestyle among young people. The HEADS (Home, Education, Eating, Activities, Drugs [i.e. substance use including tobacco, alcohol, and illegal drugs], Sexuality [including...... contraception], Safety, Self-harm) interview is a feasible way of exploring health risk behaviors and resilience. OBJECTIVE: The purpose of this study was to evaluate how often HEADS topics were addressed according to young patients and staff in pediatric and adult outpatient clinics. METHODS: We conducted...... care professionals participated. We found only small reported differences between staff and young patients regarding whether home, education, and activity were addressed. However, staff reported twice the rate of addressing smoking, alcohol, illegal drugs, sexuality, and contraception compared to young...

  1. Does the Risk of Rerevision Vary Between Porous Tantalum Cups and Other Cementless Designs After Revision Hip Arthroplasty?

    Science.gov (United States)

    Laaksonen, Inari; Lorimer, Michelle; Gromov, Kirill; Rolfson, Ola; Mäkelä, Keijo T; Graves, Stephen E; Malchau, Henrik; Mohaddes, Maziar

    2017-12-01

    Earlier results with porous tantalum acetabular cups in revision THA generally have been favorable. Recently there has been some evidence presented that porous tantalum cups might decrease the risk of rerevision in the setting of revision hip surgery performed owing to prosthetic joint infection (PJI). As the data supporting this assertion come from a study with a limited study population, examining this issue with a large registry approach may be enlightening. By combining results from two large, national registries, we asked: (1) Do porous tantalum cups show improved survival after revision THA compared with other cementless designs? (2) Does the use of porous tantalum cups influence survivorship when rerevision for PJI is the endpoint? A total of 2442 first-time THA revisions with porous tantalum cups and 4401 first-time revisions with other uncemented cups were included in this collaborative study between the Australian and Swedish national joint registries. The mean age of the patients was 69 years (range, 19-97 years), 3754 (55%) of the patients were women, and the mean followup for the porous tantalum and uncemented control groups were 3.0 years (SD, ± 2.1 years) and 3.4 years (SD, ± 2.3 years), respectively. Concomitant stem revision was more common in the porous tantalum group (43% versus 36%). The use of porous tantalum augments also was analyzed as a proxy for more complex acetabular reconstructions. In an attempt to further reduce selection bias, we performed subgroup analysis for primary operations attributable to osteoarthritis and first revision attributable to aseptic loosening. Kaplan-Meier survivorship with rerevisison for any reason up to 7 years was comparable between the porous tantalum cup group and the uncemented cup control group (86% [95% CI, 85%-89%] and 87% [95% CI, 85%-89%], respectively; p = 0.85) and the overall survivorship up to 7 years with a second revision for PJI as the endpoint (97% [95% CI, 95%-98%] and 97% [95% CI, 96

  2. Resultados preliminares da artroplastia do quadril metal-metal de superfície: análise dos primeiros 40 casos com seguimento médio de 3 anos Preliminary outcomes of hip metal-on-metal resurfacing arthroplasty: an analysis of the first 40 cases with mean follow-up time of 3 years

    Directory of Open Access Journals (Sweden)

    Mauricio de Moraes

    2008-01-01

    Full Text Available Quarenta quadris (39 pacientes foram submetidos à artroplastia total metal-metal de superficie "resurfacing" entre 2002 e 2005. Todos foram estudados e analisados clinicamente e radiograficamente. Foram utilizados critérios clínicos, no pré e pós-operatório, pela avaliação de D'Aubigné e Postel. Radiograficamente, as áreas de radiolucência ao redor do acetábulo foram classificadas de acordo com DeLee e Charnley e, no fêmur nas zonas descritas por Amstutz et al. A idade média foi de 54,40 anos. O seguimento mínimo foi de 14 meses e o máximo de 51(média de 37,36 meses. 94,44% dos resultados clínicos foram satisfatórios no pós-operatório. Ocorreram 2 casos de soltura asséptica. Não houve fratura do fêmur durante o seguimento. Os autores consideraram esta opção técnica e de implante satisfatória e, com bons resultados no seguimento médio de 3 anos.Forty hips (39 patients were submitted to metal-on-metal hip replacement (resurfacing between 2002 and 2005. Evaluation was provided by clinical examination and X-ray tests. The authors performed clinical evaluations before and after surgery. The specific criterion applied was the D'Aubigné and Postel's classification. X-ray images showed radiolucent lines around the acetabular component on the zones described by DeLee and Charnley and around the femoral component on the zones described by Amstutz et al. The mean age was 54.40 years. The minimum follow-up period was 14 months (range:12 to 51 months. The outcomes of 94.44% of the patients in the study were postoperatively rated as satisfactory. There were 2 cases of aseptic loose and no neck-femoral fractures during the follow-up period. The authors concluded that this technique and implant alternative is satisfactory, with good early outcomes in a mean follow-up time of three years.

  3. Radiographic­ behavior­ of­ cementless­ sockets­ and ­its clinical correlation

    Directory of Open Access Journals (Sweden)

    German Garabano

    2013-10-01

    Full Text Available Background Radiolucent lines between cementless acetabular components and surrounding bone can be seen frequently on the immediate postoperative X-rays. The purpose of this retrospective study was to assess the clinical and radiographic behavior, if there were changes in the cup position and survival when these lines were present. Methods One hundred and twenty one Duraloc® (Depuy J&J uncemented sockets (53 model 100 and 68 model 300 were analyzed. There were 73 men and 48 women, with an average age of 58 years and a follow-up of 5.2 years. We performed a manual measurement of the X-rays to determine the presence of the radiolucent gap between the component and the acetabular bone, and the position and orientation of the cups. When this gap was observed measurements were repeated in all follow-up X-rays. Results The gap was observed in 28 (23.14% patients (9 model 100 and 19 model 300. The average gap size was 3.5 mm, being more frequent in zone II and it was filled on average 22 months after surgery in 86% of cases. The filling was partial in two cases and it did not change in four patients. The HHS for the group with the gap was 94.3 points and that for group without the gap was 93.9 points. No loosening was detected. Conclusions The presence of radiolucent line on the immediate postoperative X-rays after placement of a cementless socket has a finite duration in the majority of cases and in line with other reports it does not represent a threat to the medium and long-term survival of the component.

  4. Radiographic evaluation of the results of total hip arthroplasty with the cementless Zweymüller endoprosthesis.

    Science.gov (United States)

    Pietrzak, Krzysztof; Piślewski, Zbigniew; Strzyzewski, Wojciech; Pucher, Andrzej; Kaczmarek, Wiesław

    2010-01-01

    Cementless endoprostheses include the Zweymüller endoprosthesis. Extensive clinical and radiological investigations were carried out in the Department of Orthopaedics and Traumatology of the University of Medical Sciences in Poznań in 180 patients who had received this endoprosthesis between 1995 and 2004. The study group was composed of 180 patients (252 hips), out of whom 138 patients (193 hips) had been operated on due to primary (idiopathic) degenerative changes and 42 patients (59 hips) had needed treatment on account of degenerative changes secondary to developmental hip dysplasia and hip joint dislocation. The mean duration of post-operative follow-up was 6 years in patients with primary degenerative changes and 7 years in patients with secondary degenerative changes. The patients were also divided into two groups according to the length of post-operative follow-up. The first group, evaluated after a follow-up of more than 10 years, was composed of 31 hips, whereas the second group, with a follow-up of up to 10 years after the surgery, comprised of 221 hips. We evaluated anteroposterior hip joint radiographs taken before the surgery, during the follow-up and at the final examination and, additionally, axial hip radiographs taken on the first post-operative day and lateral radiographs of the femur and the hip joint taken at the final examination. The radiographic evaluation was carried out according to the recommendations of the Hip Society. There was no radiographic evidence of implant loosening among the 180 patients. In the group of post-dysplastic hips, the inclination angle of the acetabular component was 29-52 ° (mean: 40.2 °) and the acetabular opening angle was 0-21 ° (mean: 7.9 °). The stem was valgus-oriented in 9 hips, varus-oriented in 11 hips and neutral-oriented in 39 hips. In the group of patients with primary degenerative changes the inclination angle of the acetabular component was 29-65 ° (mean: 42.5 °) and the opening angle was 0

  5. Computed Tomography (CT) -- Head

    Medline Plus

    Full Text Available ... of the Head? What is CT Scanning of the Head? Computed tomography, more commonly known as a ... of page What are some common uses of the procedure? CT scanning of the head is typically ...

  6. Head Impact Laboratory (HIL)

    Data.gov (United States)

    Federal Laboratory Consortium — The HIL uses testing devices to evaluate vehicle interior energy attenuating (EA) technologies for mitigating head injuries resulting from head impacts during mine/...

  7. Computed Tomography (CT) -- Head

    Medline Plus

    Full Text Available ... News Physician Resources Professions Site Index A-Z Computed Tomography (CT) - Head Computed tomography (CT) of the head uses special x-ray ... Head? What is CT Scanning of the Head? Computed tomography, more commonly known as a CT or CAT ...

  8. Developmental hip dysplasia treated by total hip arthroplasty using a cementless Wagner cone stem in young adult patients with a small physique.

    Science.gov (United States)

    Zhen, Ping; Liu, Jun; Lu, Hao; Chen, Hui; Li, Xusheng; Zhou, Shenghu

    2017-05-15

    Developmental hip dysplasia (DDH) may lead to severe acetabular and femoral abnormalities that can render total hip arthroplasty (THA) challenging, especially in DDH patients with a small physique. Most conventional cemented or cementless femoral components are often difficult to implant in the narrow femoral canal and require slight version correction during surgery. The aim of this study was to present the mid-term results of THA in the treatment of DDH patients with a small physique using a cementless Wagner cone prosthesis (Zimmer®, US). Between January 2006 and March 2010, we retrospectively reviewed 50 patients who were treated at our center. A total of 50 patients (52 hips; 45 women, five men; mean age 32.5 years; range 27 to 38 years) who underwent THA were observed. The mean femoral medullary canal dimension at the isthmus was 7.6 mm (range 6.0 to 8.7). According to the Crowe classification, 19 hips presented dysplasia of grade I, while 33 presented dysplasia of grade II. All patients were treated with THA using a cementless Wagner cone prosthesis. Clinical and radiologic evaluations were performed on all patients. The mean duration of follow-up was 7.7 years (range 5.4 to 10.5). The Harris hip score (HHS) improved from 63 ± 9 (range 55 to 70) pre-operatively to 92 ± 8 (range 88 to 100) at the last follow-up. The HHS at the most recent follow-up was excellent in 66% of patients (34 hips), good in 26% (14 hips), fair in 6% (3 hips), and poor in 2% (1 hip). Radiographic evaluation demonstrated excellent osteointegration of the implants. Stem subsidence was present in three stems, and the range of stem subsidence was 2 mm in two stems (3.9%) and 3 mm in one stem (1.9%). Femoral osteolysis was observed in nine hips (18%) in the proximal zones, and no distal osteolysis was noted. Heterotopic ossification was observed in three hips (5.8%); of these, two were classified as Brooker's grade 1, and one was classified as Brooker's grade 2 at the most

  9. Progressive glenoid bone loss caused by erosion in humeral head resurfacing.

    Science.gov (United States)

    Werner, B S; Stehle, J; Abdelkawi, A; Plumhoff, P; Hudek, R; Gohlke, F

    2017-12-01

    Cementless surface replacement of the shoulder represents an alternative to conventional stemmed anatomic prostheses. Glenoid erosion is a well-known complication in hemiarthroplasty. However, there is limited data concerning radiographic evaluation and prognostic factors for this phenomenon. The aim of our study was to determine the development of glenoid erosion following shoulder resurfacing using a new measurement technique and detect potential prognostic factors. We performed a retrospective analysis on 38 shoulders undergoing humeral head resurfacing with a mean follow-up of 65.4 ± 43 months. Clinical and radiographic evaluation followed a standardized protocol including pre- and postoperative Constant score, active range of motion, and X‑rays in true anteroposterior view. Three independent observers performed measurements of glenoid erosion. We found good interobserver reliability for glenoid erosion measurements (intraclass correlation coefficient [ICC] 0.74-0.78). Progressive glenoid erosion was present in all cases, averaging 5.5 ± 3.9 mm at more than 5 years' follow-up. Male patients demonstrated increased glenoid bone loss within the first 5 years (p erosion was 37%. Glenoid erosion can be routinely expected in patients undergoing humeral head resurfacing. Painful glenoid erosion leads to deterioration in functional outcome and necessitates revision surgery in a high percentage of cases.

  10. A Case Report of Implant Fracture of Extensively Porous-Coated, Distally Fixated Cementless Long Stem: Detailed Course of Stem Bending Development.

    Science.gov (United States)

    Mimura, Tomohiro

    2015-01-01

    We report the fracture of a cementless long stem in a distally fixated, extensively porous-coated femoral prosthesis used for revisional total hip arthroplasty (THA) 9 years previously in a 48-year-old woman, measuring 58 kg in weight and 155 cm in height. Following resolution of an infection 7 years after the revisional THA, a series of posterior dislocations occurred up until 7 months before sudden stem fracture. Extensive radiographic imaging evidence indicated a gradual progression of bending in the stem, and scanning electron microscope energy dispersive X-ray spectroscopy revealed oxygen in the medial and lateral sections, suspecting in vivo corrosion. We retrospectively examined the detailed course of stem bending development prior to stem fracture. The stem bending immediately after the revisional THA, at the first dislocation, and immediately before the stem fracture was 0°, 1.9°, and 5.2°, respectively. We consider that the cyclic loading with poor proximal bone support, distal fixation, and small diameter were the potential risk of this implant fracture. However, the course of stem bending development suggested that repeated operations and several dislocations might have aggravated the implant fatigue in the present case.

  11. A Case Report of Implant Fracture of Extensively Porous-Coated, Distally Fixated Cementless Long Stem: Detailed Course of Stem Bending Development

    Directory of Open Access Journals (Sweden)

    Tomohiro Mimura

    2015-01-01

    Full Text Available We report the fracture of a cementless long stem in a distally fixated, extensively porous-coated femoral prosthesis used for revisional total hip arthroplasty (THA 9 years previously in a 48-year-old woman, measuring 58 kg in weight and 155 cm in height. Following resolution of an infection 7 years after the revisional THA, a series of posterior dislocations occurred up until 7 months before sudden stem fracture. Extensive radiographic imaging evidence indicated a gradual progression of bending in the stem, and scanning electron microscope energy dispersive X-ray spectroscopy revealed oxygen in the medial and lateral sections, suspecting in vivo corrosion. We retrospectively examined the detailed course of stem bending development prior to stem fracture. The stem bending immediately after the revisional THA, at the first dislocation, and immediately before the stem fracture was 0°, 1.9°, and 5.2°, respectively. We consider that the cyclic loading with poor proximal bone support, distal fixation, and small diameter were the potential risk of this implant fracture. However, the course of stem bending development suggested that repeated operations and several dislocations might have aggravated the implant fatigue in the present case.

  12. Head injury - first aid

    Science.gov (United States)

    ... medlineplus.gov/ency/article/000028.htm Head injury - first aid To use the sharing features on this page, ... a concussion can range from mild to severe. First Aid Learning to recognize a serious head injury and ...

  13. Computed Tomography (CT) -- Head

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    Full Text Available ... the head is typically used to detect: bleeding, brain injury and skull fractures in patients with head injuries. ... hard time staying still, are claustrophobic or have chronic pain, you may find a CT exam to ...

  14. Head and face reconstruction

    Science.gov (United States)

    ... medlineplus.gov/ency/article/002980.htm Head and face reconstruction To use the sharing features on this page, please enable JavaScript. Head and face reconstruction is surgery to repair or reshape deformities ...

  15. Computed Tomography (CT) -- Head

    Medline Plus

    Full Text Available ... the limitations of CT Scanning of the Head? What is CT Scanning of the Head? Computed tomography, ... than regular radiographs (x-rays). top of page What are some common uses of the procedure? CT ...

  16. Computed Tomography (CT) -- Head

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    Full Text Available ... for Brain Tumors Radiation Therapy for Head and Neck Cancer Others American Stroke Association National Stroke Association ... Computer Tomography (CT) Safety During Pregnancy Head and Neck Cancer X-ray, Interventional Radiology and Nuclear Medicine ...

  17. Newborn head molding

    Science.gov (United States)

    Newborn cranial deformation; Molding of the newborn's head; Neonatal care - head molding ... The bones of a newborn baby's skull are soft and flexible, with gaps between the plates of bone. The spaces between the bony plates of ...

  18. The unipolar ASR : Viable option in unsalvageable femoral head conditions in the young patient

    Directory of Open Access Journals (Sweden)

    Marya SKS

    2006-01-01

    Full Text Available Background: The management of unsalvageable femoral head conditions in the young patient has remained an unresolved dilemma. Articular surface replacement of the hip has recently made some headway in terms of providing near-normal hip joint mechanics and function. However, this surgery has been limited to early stages of arthritis only with reasonable maintenance of head-neck congruity and morphology. Femoral neck fractures, osteonecrosis with large segment collapse, advanced arthritis with femoral incongruity, etc are traditional contraindications to the resurfacing technique. Methods: We present here a report on our series of 20 cases of unsalvageable femoral heads in young patients (age range, 27 to 52yrs, over a twelve month period (Aug 2004 to Jul 2005, treated with the unipolar ASR prosthesis. Fifteen patients (two had bilateral hip pathology had primary or secondary arthritis (degenerative, post-traumatic, ankylosing spondylitis and post-avascular necrosis while three had old operated femoral neck fractures. All patients underwent hip replacement surgery using the Unipolar ASR prosthesis. Results: Clinical and radiological results at 6-month follow up have been very encouraging and warrant further study. At an average of 4 months post-operatively, patients were able to squat, sit on the ground and perform light sporting activities. Conclusions: The Unipolar ASR prosthesis is an extension of the articular resurfacing technique employing similar principles (large size bearings, metal-on-metal interfaces, and has incorporated the advantages of the uncemented technique. We propose that this technique be more frequently used so as to brighten the prognosis of the young active patient with unsalvageable hip conditions, especially in the Asian scenario.

  19. Computed Tomography (CT) -- Head

    Medline Plus

    Full Text Available ... limitations of CT Scanning of the Head? What is CT Scanning of the Head? Computed tomography, more commonly known as a ... top of page What are some common uses of the procedure? CT scanning of the head is ...

  20. Computed Tomography (CT) -- Head

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    Full Text Available ... Computed tomography (CT) of the head uses special x-ray equipment to help assess head injuries, severe headaches, dizziness, and other symptoms of ... content. Related Articles and Media Radiation Dose in X-Ray and CT ... Perfusion of the Head CT Angiography (CTA) Stroke Brain Tumors Computer Tomography ( ...

  1. An Analytical Calculation of Frictional and Bending Moments at the Head-Neck Interface of Hip Joint Implants during Different Physiological Activities

    Directory of Open Access Journals (Sweden)

    Hamidreza Farhoudi

    2016-12-01

    Full Text Available This study predicts the frictional moments at the head-cup interface and frictional torques and bending moments acting on the head-neck interface of a modular total hip replacement across a range of activities of daily living. The predicted moment and torque profiles are based on the kinematics of four patients and the implant characteristics of a metal-on-metal implant. Depending on the body weight and type of activity, the moments and torques had significant variations in both magnitude and direction over the activity cycles. For the nine investigated activities, the maximum magnitude of the frictional moment ranged from 2.6 to 7.1 Nm. The maximum magnitude of the torque acting on the head-neck interface ranged from 2.3 to 5.7 Nm. The bending moment acting on the head-neck interface varied from 7 to 21.6 Nm. One-leg-standing had the widest range of frictional torque on the head-neck interface (11 Nm while normal walking had the smallest range (6.1 Nm. The widest range, together with the maximum magnitude of torque, bending moment, and frictional moment, occurred during one-leg-standing of the lightest patient. Most of the simulated activities resulted in frictional torques that were near the previously reported oxide layer depassivation threshold torque. The predicted bending moments were also found at a level believed to contribute to the oxide layer depassivation. The calculated magnitudes and directions of the moments, applied directly to the head-neck taper junction, provide realistic mechanical loading data for in vitro and computational studies on the mechanical behaviour and multi-axial fretting at the head-neck interface.

  2. [Clinical and radiological results of the thrust plate prosthesis in patients with aseptic necrosis of the femoral head].

    Science.gov (United States)

    Ishaque, B A; Wienbeck, S; Basad, E; Stürz, H

    2005-01-01

    In this study, we investigated the results after implantation of the thrust plate prosthesis (TPP) in patients with femoral head necrosis. We intended to answer the question if the femoral neck prosthesis, inaugurated by Huggler and Jacob in Switzerland, which needs a good bone stock for a successful implantation, is a recommendable alternative to other cementless intramedullary fixed prostheses. In a prospective study, 62 patients who had received 70 TPP because of femoral head necrosis as a result of various aetiologies between 1993 and 2004 were examined clinically and radiologically. The follow-up examinations were carried out 3 and 6 months postoperatively and subsequently once a year. The mean follow-up interval was 6.0 +/- 1.9 years (1.0-10.2 years). Clinical examination was carried out using the Harris hip score; the radiological examination was performed according to predefined criteria in an exact a.-p.-view. Four sectors can be distinguished: A corresponds to the femoral neck stump, B to the bony stock cranial (= 1) and caudal (= 2) to the mandrel of the prosthesis, C is the region above and under the bolt and D is the cortical area around the lateral plate. Furthermore, we performed a Kaplan-Meier survival rate analysis. We found excellent clinical results. The preoperative Harris score increased from 48.3 to 91.6 +/- 6.6 at 24 months after the operation. Radiolucencies of various relevancies were detected depending on the localisation. We often saw bony atrophy under the thrust plate (sector A: A 1 21.4%, A 2 9.9%) and small radiolucencies along the bolt (sector C 30 % in general). As a pathological finding we interpreted progressive radiolucencies of sector B, which was considered to be a sign of loosening, when they showed a thickness of > or = 2 mm. Therefore, we had to change one TPP. In two additional cases we saw an extended atrophy under the lateral plate, which was also interpreted to be a sign of loosening. The Kaplan-Meier survivorship

  3. Magnetic Resonance Imaging (MRI) -- Head

    Science.gov (United States)

    ... News Physician Resources Professions Site Index A-Z Magnetic Resonance Imaging (MRI) - Head Magnetic resonance imaging (MRI) of the head ... limitations of MRI of the Head? What is MRI of the Head? Magnetic resonance imaging (MRI) is ...

  4. Cementless anatomical prosthesis for the treatment of 3-part and 4-part proximal humerus fractures: cadaver study and prospective clinical study with minimum 2 years followup

    Directory of Open Access Journals (Sweden)

    Obert Laurent

    2016-01-01

    Full Text Available Introduction: The purpose of this study was to evaluate the functional and radiological outcomes of a cementless, trauma-specific locked stem for 3- and 4-part proximal humeral fractures. Materials and methods: This study consisted of two parts: a cadaver study with 22 shoulders and a multicenter prospective clinical study of 23 fracture patients evaluated at least 2 years after treatment. In the cadaver study, the locked stem (HumelockTM, FX Solutions and its instrumentation were evaluated. In the clinical study, five senior surgeons at four different hospitals performed the surgical procedures. An independent surgeon evaluated the patients using clinical (Constant score, QuickDASH and radiological (X-rays, CT scans outcome measures. Results: The cadaver study allowed us to validate the height landmarks relative to the pectoralis major tendon. In the clinical study, at the review, abduction was 95° (60–160, forward flexion was 108° (70–160, external rotation (elbow at body was 34° (0–55, the QuickDASH was 31 (4.5–59, the overall Constant score was 54 (27–75, and the weighted Constant score was 76 (31.5–109. Discussion: This preliminary study of hemiarthroplasty (HA with a locked stem found results that were at least equivalent to published series. As all patients had at least a 2-year follow-up, integration of the locked stem did not cause any specific complications. These results suggest that it is possible to avoid using cement when hemiarthroplasty is performed for the humeral stem. This implant makes height adjustment and transosseous suturing of the tuberosities more reproducible.

  5. Rifampicin-fosfomycin coating for cementless endoprostheses: antimicrobial effects against methicillin-sensitive Staphylococcus aureus (MSSA) and methicillin-resistant Staphylococcus aureus (MRSA).

    Science.gov (United States)

    Alt, Volker; Kirchhof, Kristin; Seim, Florian; Hrubesch, Isabelle; Lips, Katrin S; Mannel, Henrich; Domann, Eugen; Schnettler, Reinhard

    2014-10-01

    New strategies to decrease infection rates in cementless arthroplasty are needed, especially in the context of the growing incidence of methicillin-resistant Staphylococcus aureus (MRSA) infections. The purpose of this study was to investigate the antimicrobial activity of a rifampicin-fosfomycin coating against methicillin-sensitive Staphylococcus aureus (MSSA) and MRSA in a rabbit infection prophylaxis model. Uncoated or rifampicin-fosfomycin-coated K-wires were inserted into the intramedullary canal of the tibia in rabbits and contaminated with an inoculation dose of 10(5) or 10(6) colony-forming units of MSSA EDCC 5055 in study 1 and MRSA T6625930 in study 2, respectively. After 28days the animals were killed and clinical, histological and microbiological assessment, including pulse-field gel electrophoresis, was conducted. Positive culture growth in agar plate testing and/or clinical signs and/or histological signs were defined positive for infection. Statistical evaluation was performed using Fisher's exact test. Both studies showed a statistically significant reduction of infection rates for rifampicin-fosfomycin-coated implants compared to uncoated K-wires (P=0.015). In both studies none of the 12 animals that were treated with a rifampicin-fosfomycin-coated implant showed clinical signs of infection or a positive agar plate testing result. In both studies, one animal of the coating group showed the presence of sporadic bacteria with concomitant inflammatory signs in histology. The control groups in both studies exhibited an infection rate of 100% with clear clinical signs of infection and positive culture growth in all animals. In summary, the rifampicin-fosfomycin-coating showed excellent antimicrobial activity against both MSSA and MRSA, and therefore warrants further clinical testing. Copyright © 2014 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  6. Head Injuries in Soccer.

    Science.gov (United States)

    Myrick, Karen M

    2016-07-01

    Soccer is currently the most popular and fastest growing sport worldwide, with approximately 265 million registered soccer players existing around the world. The popularity of the sport, coupled with the high incidence of 18.8-21.5 head injuries per 1,000 player hours reported, make it essential that clinicians, coaches, and the athletes, have a solid understanding of head injuries. The successful rehabilitation of athletes with head injuries relies upon early and accurate identification strategies and implementation of appropriate return to play measures across all areas in the continuum of care. Soccer is a frequently played sport, and head injuries are common. Therefore, it is imperative that clinicians, coaches, and the athletes themselves have a solid understanding of head injury prevention, diagnosis, and treatment options. The purpose of this article was to provide rehabilitation nurses with current information regarding frequently occurring head injuries in the widespread sport of soccer. © 2015 Association of Rehabilitation Nurses.

  7. Head and Neck

    DEFF Research Database (Denmark)

    Højgaard, Liselotte; Berthelsen, Anne Kiil; Loft, Annika

    2014-01-01

    Positron emission tomography (PET)/computed tomography with FDG of the head and neck region is mainly used for the diagnosis of head and neck cancer, for staging, treatment evaluation, relapse, and planning of surgery and radio therapy. This article is a practical guide of imaging techniques......, including a detailed protocol for FDG PET in head and neck imaging, physiologic findings, and pitfalls in selected case stories....

  8. Computed Tomography (CT) -- Head

    Medline Plus

    Full Text Available ... Computed tomography (CT) of the head uses special x-ray equipment to help assess head injuries, severe headaches, ... is a diagnostic medical test that, like traditional x-rays, produces multiple images or pictures of the inside ...

  9. Head Injuries in Children

    Science.gov (United States)

    Pennington, Nicole

    2010-01-01

    School nurses play a crucial role in injury prevention and initial treatment when injuries occur at school. The role of school nurses includes being knowledgeable about the management of head injuries, including assessment and initial treatment. The school nurse must be familiar with the outcomes of a head injury and know when further evaluation…

  10. Abnormal Head Position

    Science.gov (United States)

    ... non-ocular causes of an abnormal head position? Congenital shortening of the neck muscles (sternocleidomastoid) can cause a head tilt. This is ... amblyopia) are other treatment alternatives. Physical therapy helps congenital torticollis from tight neck muscles. Updated ... Terms & Conditions Most Common ...

  11. Computed Tomography (CT) -- Head

    Medline Plus

    Full Text Available ... the limitations of CT Scanning of the Head? What is CT Scanning of the Head? Computed tomography, more commonly known as a CT or CAT scan, is a diagnostic medical test that, like traditional x-rays, produces multiple images or pictures of the inside of ...

  12. Head Start in Action.

    Science.gov (United States)

    Riley, Clara M. D.; Epps, Frances M. J.

    Records and observations from a summer Head Start program, conducted in Los Angeles by Delta Sigma Theta, are delineated in this book. It relates firsthand experiences of the participating personnel as they developed and implemented a Head Start program for some 300 children. The book is divided into three sections. Section I,…

  13. Is there added risk in resurfacing a femoral head with cysts?

    Directory of Open Access Journals (Sweden)

    Liu Fei

    2011-10-01

    Full Text Available Abstract Background Femoral head cysts have been identified as a risk factor for early femoral failures after metal-on-metal hip resurfacing arthroplasty (HRA based on limited scientific data. However, we routinely performed HRA if less than 1/3 of the femoral head appeared destroyed by cysts on the preoperative radiograph. This study was undertaken to analyze whether there was an added risk of early femoral failures in HRA when femoral head cysts were present. Methods This retrospective case-control study included 939 MOM HRAs operated by a single surgeon with use of the posterior minimally invasive surgical (MIS approach between November 2005 and January 2009. Patients with all diagnoses except osteonecrosis were included. Among them, 117 HRAs had femoral head cysts ≥ 1 cm identified in surgery. All cysts were treated with bone grafting using acetabular reamings packed into the cavitary defect (instead of filling the cysts with cement. The control group, which had no cyst observed at the time of surgery, was randomly selected from our database using computer algorithms to match those cases in the study group for the parameters of surgical date, age, gender, body mass index, diagnosis, femoral fixation method, and the size of the femoral component. Results The minimum follow-up was 24 months for both groups. The early femoral failure rate in the study group was 3/117 (2.6% and 0/117 in the control group; there was no statistical difference between these two groups (P = 0.08. In the study group, there were two femoral neck fractures (revised: both occurred in patients having a cyst size of 1 cm3; and there was one femoral component loosening at 3-year follow up in a patient having a cyst size of 2 cm3. Conclusion Although the risk of early femoral failures among the group with cysts appeared higher than the group without cysts, we could not demonstrate a significant statistical difference between the two groups. It is possible that bone

  14. Baseline head in Olkiluoto

    Energy Technology Data Exchange (ETDEWEB)

    Ahokas, H.; Tammisto, E.; Lehtimaeki, T. (Poeyry Environment Oy, Vantaa (Finland))

    2008-11-15

    As part of the programme for the final disposal of the spent nuclear fuel, Posiva Oy investigates the prevailing hydrological conditions on Olkiluoto island. The hydrological investigations have included several kinds of hydrological tests such as measurements of hydraulic conductivity by flow logging and a double-packer tool as well as interference tests by pumping, in order to study the hydraulic connections between the drillholes. In addition, long-term monitoring of groundwater level and groundwater head as well as measurements of flow conditions in open drillholes, groundwater salinity (in situ EC), precipitation (including snow), sea-water level, surface flow (runoff) etc. have been part of the investigation programme aiming at the characterization of the bedrock. The data have been used in the compilation of deterministic hydro-zones and hydraulic properties for numerical flow modelling to study the flow pattern on Olkiluoto island. In addition, the compiled bedrock models have been used in the planning of the repository layout and in the analyses of the transport of radionuclides and the functionality of engineered barriers. This report focuses on the measurements of groundwater head by means of multi-packers and in connection with flow loggings. The determination of the undisturbed groundwater head (baseline head) in terms of the in situ fresh water head is the main goal of this report. The density of groundwater is strongly dependent on salinity and due to the saline groundwater deep in the bedrock in Olkiluoto the term fresh water head is used instead of hydraulic head. Taking the density of groundwater into account, the gradient of the residual pressure, which actually causes groundwater flow can be calculated. The measured and calculated heads are converted into corresponding in situ fresh water heads, which correspond to the water level (metres above sea level) in the hose that runs from the packed-off section to the ground surface. This means that

  15. Magnetic Resonance Imaging (MRI) -- Head

    Medline Plus

    Full Text Available ... the limitations of MRI of the Head? What is MRI of the Head? Magnetic resonance imaging (MRI) is a noninvasive ... top of page What are some common uses of the procedure? MR imaging of the head is ...

  16. Magnetic Resonance Imaging (MRI) -- Head

    Medline Plus

    Full Text Available ... MRI of the Head? What is MRI of the Head? Magnetic resonance imaging (MRI) is a noninvasive ... of page What are some common uses of the procedure? MR imaging of the head is performed ...

  17. Ulnar head replacement.

    Science.gov (United States)

    Herbert, Timothy J; van Schoonhoven, Joerg

    2007-03-01

    Recent years have seen an increasing awareness of the anatomical and biomechanical significance of the distal radioulnar joint (DRUJ). With this has come a more critical approach to surgical management of DRUJ disorders and a realization that all forms of "excision arthroplasty" can only restore forearm rotation at the expense of forearm stability. This, in turn, has led to renewed interest in prosthetic replacement of the ulnar head, a procedure that had previously fallen into disrepute because of material failures with early implants, in particular, the Swanson silicone ulnar head replacement. In response to these early failures, a new prosthesis was developed in the early 1990s, using materials designed to withstand the loads across the DRUJ associated with normal functional use of the upper limb. Released onto the market in 1995 (Herbert ulnar head prosthesis), clinical experience during the last 10 years has shown that this prosthesis is able to restore forearm function after ulnar head excision and that the materials (ceramic head and noncemented titanium stem), even with normal use of the limb, are showing no signs of failure in the medium to long term. As experience with the use of an ulnar head prosthesis grows, so does its acceptance as a viable and attractive alternative to more traditional operations, such as the Darrach and Sauve-Kapandji procedures. This article discusses the current indications and contraindications for ulnar head replacement and details the surgical procedure, rehabilitation, and likely outcomes.

  18. Computed Tomography (CT) -- Head

    Medline Plus

    Full Text Available ... you! Do you have a personal story about radiology? Share your patient story here Images × Image Gallery ... Pregnancy Head and Neck Cancer X-ray, Interventional Radiology and Nuclear Medicine Radiation Safety Images related to ...

  19. Computed Tomography (CT) -- Head

    Medline Plus

    Full Text Available ... Tomography (CT) Safety During Pregnancy Head and Neck Cancer X-ray, Interventional Radiology and Nuclear ... or other physician. To locate a medical imaging or radiation oncology provider in your community, you can search the ...

  20. Overview of Head Injuries

    Science.gov (United States)

    ... brain. If the head injury is very severe, mechanical ventilation may be used. Doctors control blood pressure and minimize the amount of brain swelling by adjusting the amount of intravenous fluids given and sometimes by giving intravenous drugs that ...

  1. Computed Tomography (CT) -- Head

    Medline Plus

    Full Text Available ... headaches, dizziness, and other symptoms of aneurysm, bleeding, stroke and brain tumors. It also helps your doctor ... scanning provides more detailed information on head injuries, stroke , brain tumors and other brain diseases than regular ...

  2. Computed Tomography (CT) -- Head

    Medline Plus

    Full Text Available ... be necessary. Your doctor will explain the exact reason why another exam is requested. Sometimes a follow- ... limitations of CT Scanning of the Head? A person who is very large may not fit into ...

  3. Computed Tomography (CT) -- Head

    Medline Plus

    Full Text Available ... medically necessary because of potential risk to the baby. This risk is, however, minimal with head CT ... intravenous contrast indicate mothers should not breastfeed their babies for 24-48 hours after contrast medium is ...

  4. Computed Tomography (CT) -- Head

    Medline Plus

    Full Text Available ... assess head injuries, severe headaches, dizziness, and other symptoms of aneurysm, bleeding, stroke and brain tumors. It ... within the brain shortly after a patient exhibits symptoms of a stroke. a stroke, especially with a ...

  5. Computed Tomography (CT) -- Head

    Medline Plus

    Full Text Available ... scans in children should always be done with low-dose technique. top of page What are the ... page Additional Information and Resources RTAnswers.org Radiation Therapy for Brain Tumors Radiation Therapy for Head and ...

  6. Computed Tomography (CT) -- Head

    Medline Plus

    Full Text Available ... this tunnel. Rotating around you, the x-ray tube and electronic x-ray detectors are located opposite ... medically necessary because of potential risk to the baby. This risk is, however, minimal with head CT ...

  7. Computed Tomography (CT) -- Head

    Medline Plus

    Full Text Available ... microphone. top of page How does the procedure work? In many ways CT scanning works very much ... head CT scanning. Manufacturers of intravenous contrast indicate mothers should not breastfeed their babies for 24-48 ...

  8. Computed Tomography (CT) -- Head

    Medline Plus

    Full Text Available ... special x-ray equipment to help assess head injuries, severe headaches, dizziness, and other symptoms of aneurysm, ... cancer. In emergency cases, it can reveal internal injuries and bleeding quickly enough to help save lives. ...

  9. Computed Tomography (CT) -- Head

    Medline Plus

    Full Text Available ... traditional x-rays, particularly of soft tissues and blood vessels. CT scanning provides more detailed information on head injuries, stroke , brain tumors and other brain diseases than regular radiographs (x-rays). top of page ...

  10. Computed Tomography (CT) -- Head

    Medline Plus

    Full Text Available ... used to detect: bleeding, brain injury and skull fractures in patients with head injuries. bleeding caused by ... a few seconds, and even faster in small children. Such speed is beneficial for all patients but ...

  11. TCGA head Neck

    Science.gov (United States)

    Investigators with The Cancer Genome Atlas (TCGA) Research Network have discovered genomic differences – with potentially important clinical implications – in head and neck cancers caused by infection with the human papillomavirus (HPV).

  12. Computed Tomography (CT) -- Head

    Medline Plus

    Full Text Available ... microphone. top of page How does the procedure work? In many ways CT scanning works very much ... for Head and Neck Cancer Others American Stroke Association National Stroke Association top of page This page ...

  13. Computed Tomography (CT) -- Head

    Medline Plus

    Full Text Available ... images of internal organs, bones, soft tissue and blood vessels provide greater detail than traditional x-rays, particularly of soft tissues and blood vessels. CT scanning provides more detailed information on head ...

  14. Computed Tomography (CT) -- Head

    Medline Plus

    Full Text Available ... sometimes compared to looking into a loaf of bread by cutting the loaf into thin slices. When ... for Brain Tumors Radiation Therapy for Head and Neck Cancer Others American Stroke Association National Stroke Association ...

  15. Early Head Start Evaluation

    Data.gov (United States)

    U.S. Department of Health & Human Services — Longitudinal information from an evaluation where children were randomly assigned to Early Head Start or community services as usual;direct assessments and...

  16. Head Start Impact Study

    Data.gov (United States)

    U.S. Department of Health & Human Services — Nationally representative, longitudinal information from an evaluation where children were randomly assigned to Head Start or community services as usual;direct...

  17. Head CT scan

    Science.gov (United States)

    ... be: Stored Viewed on a monitor Printed on film Three-dimensional models of the head area can ... when you have certain other signs or symptoms Hearing loss (in some people) Symptoms of damage to ...

  18. Computed Tomography (CT) -- Head

    Medline Plus

    Full Text Available ... and other symptoms of aneurysm, bleeding, stroke and brain tumors. It also helps your doctor to evaluate your ... provides more detailed information on head injuries, stroke , brain tumors and other brain diseases than regular radiographs (x- ...

  19. Head and Neck Cancer

    Science.gov (United States)

    ... increase the risk of head and neck cancer. Environmental or occupational inhalants. Inhaling asbestos, wood dust, paint ... from the American Society of Clinical Oncology. Review dictionary articles to help understand medical phrases and terms ...

  20. Computed Tomography (CT) -- Head

    Medline Plus

    Full Text Available ... used to detect: bleeding, brain injury and skull fractures in patients with head injuries. bleeding caused by ... are present in the paranasal sinuses. plan radiation therapy for cancer of the brain or other tissues. ...

  1. Computed Tomography (CT) -- Head

    Medline Plus

    Full Text Available ... used to detect: bleeding, brain injury and skull fractures in patients with head injuries. bleeding caused by ... is also performed to: evaluate the extent of bone and soft tissue damage in patients with facial ...

  2. Cementless total hip arthroplasty for patients with Crowe type III or IV developmental dysplasia of the hip: two-stage total hip arthroplasty following skeletal traction after soft tissue release for irreducible hips.

    Science.gov (United States)

    Yoon, Pil Whan; Kim, Jung Il; Kim, Dong Ok; Yu, Cheol Hwan; Yoo, Jeong Joon; Kim, Hee Joong; Yoon, Kang Sup

    2013-09-01

    Total hip arthroplasty (THA) for severe developmental dysplasia of the hip (DDH) is a technically demanding procedure for arthroplasty surgeons, and it is often difficult to reduce the hip joint without soft tissue release due to severe flexion contracture. We performed two-stage THAs in irreducible hips with expected lengthening of the affected limb after THA of over 2.5 cm or with flexion contractures of greater than 30 degrees in order to place the acetabular cup in the true acetabulum and to prevent neurologic deficits associated with acute elongation of the limb. The purpose of this study is to evaluate the outcomes of cementless THA in patients with severe DDH with a special focus on the results of two-stage THA. Retrospective clinical and radiological evaluations were done on 17 patients with Crowe type III or IV developmental DDH treated by THA. There were 14 women and 3 men with a mean age of 52.3 years. Follow-ups averaged 52 months. Six cases were treated with two-stage THA followed by surgical hip liberalization and skeletal traction for 2 weeks. The mean Harris hip score improved from 40.9 to 89.1, and mean leg length discrepancy (LLD) in 13 unilateral cases was reduced from 2.95 to 0.8 cm. In the patients who underwent two-stage surgery, no nerve palsy was observed, and the single one-stage patient with incomplete peroneal nerve palsy recovered fully 4 weeks postoperatively. The short-term clinical and radiographic outcomes of primary cementless THA for patients with Crowe type III or IV DDH were encouraging. Two-stage THA followed by skeletal traction after soft tissue release could provide alternative solutions to the minimization of limb shortenings or LLD without neurologic deficits in highly selected patients.

  3. Magnetic Resonance Imaging (MRI) -- Head

    Medline Plus

    Full Text Available ... News Physician Resources Professions Site Index A-Z Magnetic Resonance Imaging (MRI) - Head Magnetic resonance imaging (MRI) of the head ... limitations of MRI of the Head? What is MRI of the Head? Magnetic resonance imaging (MRI) is ...

  4. Magnetic Resonance Imaging (MRI) -- Head

    Medline Plus

    Full Text Available ... Physician Resources Professions Site Index A-Z Magnetic Resonance Imaging (MRI) - Head Magnetic resonance imaging (MRI) of the head uses a powerful ... Head? What is MRI of the Head? Magnetic resonance imaging (MRI) is a noninvasive medical test that ...

  5. Pediatric head injury.

    Science.gov (United States)

    Tulipan, N

    1998-01-01

    Pediatric head injury is a public health problem that exacts a high price from patients, their families and society alike. While much of the brain damage in head-injured patients occurs at the moment of impact, secondary injuries can be prevented by aggressive medical and surgical intervention. Modern imaging devices have simplified the task of diagnosing intracranial injuries. Recent advances in monitoring technology have made it easier to assess the effectiveness of medical therapy. These include intracranial pressure monitoring devices that are accurate and safe, and jugular bulb monitoring which provides a continuous, qualitative measure of cerebral blood flow. The cornerstones of treatment remain hyperventilation and osmotherapy. Despite maximal treatment, however, the mortality and morbidity associated with pediatric head injury remains high. Reduction of this mortality and morbidity will likely depend upon prevention rather than treatment.

  6. Impaction grafting in the femur in cementless modular revision total hip arthroplasty: a descriptive outcome analysis of 243 cases with the MRP-TITAN revision implant

    Directory of Open Access Journals (Sweden)

    Wimmer Matthias D

    2013-01-01

    .1% after 8.7 years]. Radiologic evaluation showed no significant change in axial implant migration (4.3% vs. 9.3%; p = 0.19 but a significant reduction in proximal stress shielding (5.7% vs. 17.9%; p  Conclusion We present the largest analysis of the impaction grafting technique in combination with cementless distal diaphyseal stem fixation published so far. Our data provides initial evidence of improved bone regeneration after graft augmentation of metaphyseal bone defects. The data suggests that proximal metaphyseal graft augmentation is beneficial for large metaphyseal bone defects (Paprosky types IIC and III and stem diameters of 17 mm and above. Due to the limitations of a retrospective and descriptive study the level of evidence remains low and prospective trials should be conducted.

  7. Head First Statistics

    CERN Document Server

    Griffiths, Dawn

    2009-01-01

    Wouldn't it be great if there were a statistics book that made histograms, probability distributions, and chi square analysis more enjoyable than going to the dentist? Head First Statistics brings this typically dry subject to life, teaching you everything you want and need to know about statistics through engaging, interactive, and thought-provoking material, full of puzzles, stories, quizzes, visual aids, and real-world examples. Whether you're a student, a professional, or just curious about statistical analysis, Head First's brain-friendly formula helps you get a firm grasp of statistics

  8. Head and Neck Reconstruction.

    Science.gov (United States)

    Wong, Shannon; Melin, Alyson; Reilly, Debra

    2017-10-01

    Management of head and neck burns involves acute and intermediate phases. Acutely, the goals are establish a secure airway and treat life-threatening injuries. Then, optimize nutrition, assess extent of the burn, perform local wound care, and provide eye protection. Management depends on the degree of the head and neck burn. Postinjury splinting and rehabilitation are vital to healing. After the acute inflammation has resolved and the scars have matured, reconstruction begins with the goals of restoring both function and aesthetics. Reconstruction ranges from simple scar release, to skin grafting, and possibly free flap reconstruction. Copyright © 2017 Elsevier Inc. All rights reserved.

  9. Head first Ajax

    CERN Document Server

    Riordan, Rebecca M

    2008-01-01

    Ajax is no longer an experimental approach to website development, but the key to building browser-based applications that form the cornerstone of Web 2.0. Head First Ajax gives you an up-to-date perspective that lets you see exactly what you can do -- and has been done -- with Ajax. With it, you get a highly practical, in-depth, and mature view of what is now a mature development approach. Using the unique and highly effective visual format that has turned Head First titles into runaway bestsellers, this book offers a big picture overview to introduce Ajax, and then explores the use of ind

  10. Computed Tomography (CT) -- Head

    Medline Plus

    Full Text Available Toggle navigation Test/Treatment Patient Type Screening/Wellness Disease/Condition Safety En Español More Info Images/Videos ... head injuries, stroke , brain tumors and other brain diseases than regular radiographs (x-rays). top of page ...

  11. Lubricating the swordfish head

    NARCIS (Netherlands)

    Videler, John J.; Haydar, Deniz; Snoek, Roelant; Hoving, Henk-Jan T.; Szabo, Ben G.

    The swordfish is reputedly the fastest swimmer on Earth. The concave head and iconic sword are unique characteristics, but how they contribute to its speed is still unknown. Recent computed tomography scans revealed a poorly mineralised area near the base of the rostrum. Here we report, using

  12. Waco Head Start Program.

    Science.gov (United States)

    Porter, Para

    The Economic Opportunity Act of 1964 led to the formation of three separate Head Start Programs in Waco, Texas. The first year, 1,500 children were involved. Of these, 40 percent were Negro, 30 percent Latin American, and 30 percent white. All teachers received a week of preparatory study at the University of Texas. The program involved four areas…

  13. Computed Tomography (CT) -- Head

    Medline Plus

    Full Text Available Toggle navigation Test/Treatment Patient Type Screening/Wellness Disease/Condition Safety En Español More Info Images/Videos About Us News Physician Resources Professions Site Index A-Z Computed Tomography (CT) - Head ...

  14. Ultrasound: Head (For Parents)

    Science.gov (United States)

    ... a safe and painless test that uses sound waves to make images of the brain. During the examination, an ultrasound machine sends sound ... The fontanel provides an opening for the sound waves to get through and reach the brain. Why It's Done Doctors order head ultrasounds when ...

  15. Silva as the Head

    DEFF Research Database (Denmark)

    Svabo, Connie

    2015-01-01

    The head of the performance design programme is substituted by a sister's academy delegate. this performance situation formed part of a week of semesterstart where the students and professors visited Sister's Academy, Malmø. I participated in the Sister's Academy as visiting researcher and here...

  16. Computed Tomography (CT) -- Head

    Medline Plus

    Full Text Available ... full size with caption Pediatric Content Some imaging tests and treatments have special pediatric considerations. The teddy bear denotes child-specific content. Related Articles and Media Radiation Dose in X-Ray and CT Exams Blood Clots CT Perfusion of the Head CT Angiography ( ...

  17. Head nurses as middle managers.

    Science.gov (United States)

    Johnston, P F

    1983-11-01

    The relationship between head nurses and their staff nurses influences staff turnover rates and job satisfaction. In this article the author describes the measures taken by the management of Greater Southeast Community Hospital in response to an increasing turnover rate among staff RNs. In recognition of the head nurse role vis-d-vis attrition rates and job satisfaction, head nurses were upgraded to department head status and rigorous head nurse performance standards were developed. These standards required clinical expertise, managerial competence, and accountability. It is the author's contention that clinical practice and staff morale are directly related to a clearly defined head nurse role.

  18. Head injuries, heading, and the use of headgear in soccer.

    Science.gov (United States)

    Niedfeldt, Mark W

    2011-01-01

    Soccer has more than 265 million players around the world and is the only contact sport with purposeful use of the head for controlling and advancing the ball. Head contact in soccer has the potential to cause acute traumatic brain injury including concussion or, potentially, a pattern of chronic brain injury. Although early retrospective research on the effects of soccer heading seemed to suggest that purposeful heading may contribute to long-term cognitive impairment, prospective controlled studies do not support this and, in fact, suggest that purposeful heading may not be a risk factor for cognitive impairment. Headgear has not been shown to be effective in reducing ball impact but may be helpful in reducing the force of non-ball-related impacts to the head. There are concerns that universal use of headgear may cause more aggressive heading and head challenges, leading to increased risk of injury.

  19. Radial Head Fractures

    Science.gov (United States)

    Jordan, Robert W.; Jones, Alistair DR.

    2017-01-01

    Background: Radial head fractures are common elbow injuries in adults and are frequently associated with additional soft tissue and bone injuries. Methods: A literature search was performed and the authors’ personal experiences are reported. Results: Mason type I fractures are treated non-operatively with splinting and early mobilisation. The management of Mason type II injuries is less clear with evidence supporting both non-operative treatment and internal fixation. The degree of intra-articular displacement and angulation acceptable for non-operative management has yet to be conclusively defined. Similarly the treatment of type III and IV fractures remain controversial. Traditional radial head excision is associated with valgus instability and should be considered only for patients with low functional demands. Comparative studies have shown improved results from internal fixation over excision. Internal fixation should only be attempted when anatomic reduction and initiation of early motion can be achieved. Authors have reported that results from fixation are poorer and complication rates are higher if more than three fragments are present. Radial head arthroplasty aims to reconstruct the native head and is indicated when internal fixation is not feasible and in the presence of complex elbow injuries. Overstuffing of the radiocapitellar joint is a frequent technical fault and has significant adverse effects on elbow biomechanics. Modular design improves the surgeon’s ability to reconstruct the native joint. Two randomised controlled trials have shown improved clinical outcomes and lower complication rate following arthroplasty when compared to internal fixation. Conclusion: We have presented details regarding the treatment of various types of radial head fractures - further evidence, however, is still required to provide clarity over the role of these different management strategies. PMID:29290880

  20. Magnetic Resonance Imaging (MRI) -- Head

    Medline Plus

    Full Text Available ... News Physician Resources Professions Site Index A-Z Magnetic Resonance Imaging (MRI) - Head Magnetic resonance imaging (MRI) of the head uses a powerful magnetic field, radio waves and a computer to produce ...

  1. Magnetic Resonance Imaging (MRI) -- Head

    Medline Plus

    Full Text Available ... content. Related Articles and Media MR Angiography (MRA) Magnetic Resonance, Functional (fMRI) - Brain Head and Neck Cancer Treatment Brain Tumor Treatment Magnetic Resonance Imaging (MRI) Safety Alzheimer's Disease Head Injury Brain ...

  2. Magnetic Resonance Imaging (MRI) -- Head

    Medline Plus

    Full Text Available ... Articles and Media MR Angiography (MRA) Magnetic Resonance, Functional (fMRI) - Brain Head and Neck Cancer Treatment Brain Tumor Treatment Magnetic Resonance Imaging (MRI) Safety Alzheimer's Disease Head Injury Brain Tumors Images related to ...

  3. Magnetic Resonance Imaging (MRI) -- Head

    Medline Plus

    Full Text Available ... are the limitations of MRI of the Head? What is MRI of the Head? Magnetic resonance imaging ( ... brain) in routine clinical practice. top of page What are some common uses of the procedure? MR ...

  4. Childhood Head and Neck Irradiation

    Science.gov (United States)

    ... Thyroid Association ® www.thyroid.org Childhood Head & Neck Irradiation What is the thyroid gland? The thyroid gland ... Thyroid Association ® www.thyroid.org Childhood Head & Neck Irradiation Thyroid nodules (see Thyroid Nodule brochure) • Thyroid nodules ...

  5. Magnetic Resonance Imaging (MRI) -- Head

    Medline Plus

    Full Text Available ... for Brain Tumors Radiation Therapy for Head and Neck Cancer Others : American Stroke Association National Stroke Association ... MRA) Magnetic Resonance, Functional (fMRI) - Brain Head and Neck Cancer Treatment Brain Tumor Treatment Magnetic Resonance Imaging ( ...

  6. Where are we heading

    Energy Technology Data Exchange (ETDEWEB)

    Noto, L.A. [Mobil Corporation, (United States)

    1996-12-31

    The present paper deals with different aspects connected to the global petroleum industry by discussing the way of heading. The aspects cover themes like new frontiers, new relationships, sanctions, global climate change, new alliances and new technology. New frontiers and relationships concern domestic policy affecting the industry, and sanctions are discussed in connection with trade. The author discusses the industry`s participation in the global environmental policy and new alliances to provide greater opportunity for developing new technology

  7. Radial Head Fractures

    OpenAIRE

    Jordan, Robert W.; Jones, Alistair DR.

    2017-01-01

    Background: Radial head fractures are common elbow injuries in adults and are frequently associated with additional soft tissue and bone injuries. Methods: A literature search was performed and the authors’ personal experiences are reported. Results: Mason type I fractures are treated non-operatively with splinting and early mobilisation. The management of Mason type II injuries is less clear with evidence supporting both non-operative treatment and internal fixation. The degree of intra-arti...

  8. On the matter of synovial fluid lubrication: implications for Metal-on-Metal hip tribology.

    Science.gov (United States)

    Myant, Connor; Cann, Philippa

    2014-06-01

    Artificial articular joints present an interesting, and difficult, tribological problem. These bearing contacts undergo complex transient loading and multi axes kinematic cycles, over extremely long periods of time (>10 years). Despite extensive research, wear of the bearing surfaces, particularly metal-metal hips, remains a major problem. Comparatively little is known about the prevailing lubrication mechanism in artificial joints which is a serious gap in our knowledge as this determines film formation and hence wear. In this paper we review the accepted lubrication models for artificial hips and present a new concept to explain film formation with synovial fluid. This model, recently proposed by the authors, suggests that interfacial film formation is determined by rheological changes local to the contact and is driven by aggregation of synovial fluid proteins. The implications of this new mechanism for the tribological performance of new implant designs and the effect of patient synovial fluid properties are discussed. Copyright © 2014 Elsevier Ltd. All rights reserved.

  9. Head First Web Design

    CERN Document Server

    Watrall, Ethan

    2008-01-01

    Want to know how to make your pages look beautiful, communicate your message effectively, guide visitors through your website with ease, and get everything approved by the accessibility and usability police at the same time? Head First Web Design is your ticket to mastering all of these complex topics, and understanding what's really going on in the world of web design. Whether you're building a personal blog or a corporate website, there's a lot more to web design than div's and CSS selectors, but what do you really need to know? With this book, you'll learn the secrets of designing effecti

  10. "E" Heating Head

    Science.gov (United States)

    Fox, Robert L.; Swaim, Robert J.; Johnson, Samuel D.; Coultrip, Robert H.; Phillips, W. Morris; Copeland, Carl E.

    1994-01-01

    Two separate areas heated inductively for adhesive bonding in single operation. "E" heating head developed to satisfy need for fast-acting and reliable induction heating device. Used in attaching "high-hat" stiffeners to aircraft panels. Incorporates principles and circuitry of toroid joining gun. Width and length configured to provide variously sized heat zones, depending on bonding requirements. Lightweight, portable and provides rapid, reliable heating of dual areas in any environment. Well suited for flight-line and depot maintenance, and battlefield repair. Also useful in automotive assembly lines to strengthen automobile panels.

  11. Head First Python

    CERN Document Server

    Barry, Paul

    2010-01-01

    Ever wished you could learn Python from a book? Head First Python is a complete learning experience for Python that helps you learn the language through a unique method that goes beyond syntax and how-to manuals, helping you understand how to be a great Python programmer. You'll quickly learn the language's fundamentals, then move onto persistence, exception handling, web development, SQLite, data wrangling, and Google App Engine. You'll also learn how to write mobile apps for Android, all thanks to the power that Python gives you. We think your time is too valuable to waste struggling with

  12. Head first C#

    CERN Document Server

    Stellman, Andrew

    2010-01-01

    You want to learn C# programming, but you're not sure you want to suffer through another tedious technical book. You're in luck: Head First C# introduces this language in a fun, visual way. You'll quickly learn everything from creating your first program to learning sophisticated coding skills with C# 4.0, Visual Studio 2010 and .NET 4, while avoiding common errors that frustrate many students. The second edition offers several hands-on labs along the way to help you build and test programs using skills you've learned up to that point. In the final lab, you'll put everything together. From o

  13. Head first C#

    CERN Document Server

    Stellman, Andrew

    2008-01-01

    Head First C# is a complete learning experience for object-oriented programming, C#, and the Visual Studio IDE. Built for your brain, this book covers C# 3.0 and Visual Studio 2008, and teaches everything from language fundamentals to advanced topics including garbage collection, extension methods, and double-buffered animation. You'll also master C#'s hottest and newest syntax, LINQ, for querying SQL databases, .NET collections, and XML documents. By the time you're through, you'll be a proficient C# programmer, designing and coding large-scale applications. Every few chapters you will come

  14. Head First Mobile Web

    CERN Document Server

    Gardner, Lyza; Grigsby, Jason

    2011-01-01

    Despite the huge number of mobile devices and apps in use today, your business still needs a website. You just need it to be mobile. Head First Mobile Web walks you through the process of making a conventional website work on a variety smartphones and tablets. Put your JavaScript, CSS media query, and HTML5 skills to work-then optimize your site to perform its best in the demanding mobile market. Along the way, you'll discover how to adapt your business strategy to target specific devices. Navigate the increasingly complex mobile landscapeTake both technical and strategic approaches to mobile

  15. HEADS UP : Sensorimotor control of the head-neck system

    NARCIS (Netherlands)

    Forbes, P.A.

    2014-01-01

    Head-neck stabilization is inherently challenging even when stationary, requiring constant vigilance to counter the downward pull of gravity. It involves a highly complex biomechanical system comprised of a large mass (the head) balanced on top of seven vertebrae (the neck), that are in turn

  16. Womanhood in Bessie Head's fiction

    African Journals Online (AJOL)

    confronted with gender discrimination in addition ;to the racial and ethnic marginality she had suffered since childhood. When the discovery of. Margaret's Basarwa origins culminate in the decision to get rid of her, Head points to the multiplicity of her problems. Head demonstrates that Margaret's womanhood comes into ...

  17. Analytical modelling of soccer heading

    Indian Academy of Sciences (India)

    Heading occur frequently in soccer games and studies have shown that repetitive heading of the soccer ball could result in degeneration of brain cells and lead to mild traumatic brain injury. This study proposes a two degree-of-freedom linear mathematical model to study the impact of the soccer ball on the brain. The model ...

  18. The head-mounted microscope.

    Science.gov (United States)

    Chen, Ting; Dailey, Seth H; Naze, Sawyer A; Jiang, Jack J

    2012-04-01

    Microsurgical equipment has greatly advanced since the inception of the microscope into the operating room. These advancements have allowed for superior surgical precision and better post-operative results. This study focuses on the use of the Leica HM500 head-mounted microscope for the operating phonosurgeon. The head-mounted microscope has an optical zoom from 2× to 9× and provides a working distance from 300 mm to 700 mm. The headpiece, with its articulated eyepieces, adjusts easily to head shape and circumference, and offers a focus function, which is either automatic or manually controlled. We performed five microlaryngoscopic operations utilizing the head-mounted microscope with successful results. By creating a more ergonomically favorable operating posture, a surgeon may be able to obtain greater precision and success in phonomicrosurgery. Phonomicrosurgery requires the precise manipulation of long-handled cantilevered instruments through the narrow bore of a laryngoscope. The head-mounted microscope shortens the working distance compared with a stand microscope, thereby increasing arm stability, which may improve surgical precision. Also, the head-mounted design permits flexibility in head position, enabling operator comfort, and delaying musculoskeletal fatigue. A head-mounted microscope decreases the working distance and provides better ergonomics in laryngoscopic microsurgery. These advances provide the potential to promote precision in phonomicrosurgery. Copyright © 2011 The American Laryngological, Rhinological, and Otological Society, Inc.

  19. 49 CFR 572.112 - Head assembly.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 7 2010-10-01 2010-10-01 false Head assembly. 572.112 Section 572.112... 50th Percentile Male § 572.112 Head assembly. The head assembly consists of the head (drawing 78051-61X...) accelerometers that are mounted in conformance to § 572.36 (c). (a) Test procedure. (1) Soak the head assembly in...

  20. 49 CFR 572.192 - Head assembly.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 7 2010-10-01 2010-10-01 false Head assembly. 572.192 Section 572.192... Dummy, Small Adult Female § 572.192 Head assembly. (a) The head assembly consists of the head (180-1000...) of this section, the head assembly shall meet performance requirements specified in paragraph (c) of...

  1. A finite element study on the mechanical response of the head-neck interface of hip implants under realistic forces and moments of daily activities: Part 1, level walking.

    Science.gov (United States)

    Farhoudi, Hamidreza; Fallahnezhad, Khosro; Oskouei, Reza H; Taylor, Mark

    2017-11-01

    This paper investigates the mechanical response of a modular head-neck interface of hip joint implants under realistic loads of level walking. The realistic loads of the walking activity consist of three dimensional gait forces and the associated frictional moments. These forces and moments were extracted for a 32mm metal-on-metal bearing couple. A previously reported geometry of a modular CoCr/CoCr head-neck interface with a proximal contact was used for this investigation. An explicit finite element analysis was performed to investigate the interface mechanical responses. To study the level of contribution and also the effect of superposition of the load components, three different scenarios of loading were studied: gait forces only, frictional moments only, and combined gait forces and frictional moments. Stress field, micro-motions, shear stresses and fretting work at the contacting nodes of the interface were analysed. Gait forces only were found to significantly influence the mechanical environment of the head-neck interface by temporarily extending the contacting area (8.43% of initially non-contacting surface nodes temporarily came into contact), and therefore changing the stress field and resultant micro-motions during the gait cycle. The frictional moments only did not cause considerable changes in the mechanical response of the interface (only 0.27% of the non-contacting surface nodes temporarily came into contact). However, when superposed with the gait forces, the mechanical response of the interface, particularly micro-motions and fretting work, changed compared to the forces only case. The normal contact stresses and micro-motions obtained from this realistic load-controlled study were typically in the range of 0-275MPa and 0-38µm, respectively. These ranges were found comparable to previous experimental displacement-controlled pin/cylinder-on-disk fretting corrosion studies. Copyright © 2017 Elsevier Ltd. All rights reserved.

  2. Landslides at Beachy Head, Sussex

    OpenAIRE

    Pennington, Catherine

    2007-01-01

    Beachy Head (Figures 1 and 2) is a famous natural and historic site and tourist attraction on the south coast. The cliff top area is part of the Downland Country Park managed by Eastbourne District Council. The section of cliff surveyed at Beachy Head is situated to the east of the modern lighthouse. The survey spans a 400 m south-facing stretch of beach with a cliff height of between 120 and 160 m. Cliffs and lighthouse at Beachy Head As part of a programme of work monitoring coast...

  3. Return of the talking heads

    DEFF Research Database (Denmark)

    Reinecke Hansen, Kenneth; Bro, Peter; Andersson, Ralf

    2016-01-01

    . In order to analyze the latest development entering the third wave, we propose a theoretically based dramaturgical model for the television news item. The analysis concludes that, with the current ‘return’ of the talking heads format, the pre-produced and pre-packaged bulletin program about past events......The present article suggests that the brief history of Western television news dramaturgy can be expounded as three major waves: from the early days of the talking heads in the studio, over the narrativization of the field report to a (re-)current studio- and field-based talking heads format...

  4. Counting heads in Cairo.

    Science.gov (United States)

    1994-09-14

    Representatives of 182 nations gathered in Cairo in September, 1994, at the Un Conference on Population and Development. The resulting 113-page Draft Program of Action contains sober discussions on demographic issues, including projections of population increase in the decades ahead. It focuses on the potential growth of famine, disease, warfare, environmental degradation, and general human misery if the world's population cannot be stabilized at around 8 billion in the next 20 years. The 1994 figure stands at about 5.7 billion, and there will be 12.5 billion people if no action is taken. Previous conferences hosted under the UN helped spark a remarkable decline in fertility rates, especially in Indonesia and Thailand. Even in populous Bangladesh, some 40% of women now use contraceptives, while the fertility rate has dropped from 7 to 4.2 in 2 decades. The proposals debated in Cairo include sustainable development, gender equality, and the empowerment of women. Whatever the country or culture, fertility rates tend to fall dramatically as women become more educated. This has been borne out almost everywhere, most notably in Japan and Singapore. The conference has been criticized by the Vatican as advocating an international standard for easy abortion, encouraging sex education for teenagers, and sanctioning marriages other than between a man and a woman. Some conservative Muslim thinkers have also complained that it promotes Western values and fosters illicit sex. Many supporters of population planning have argued that the empowerment of women will reduce the incidence of abortion. The Cairo document will alienate many across Asia with its references to the plurality of family forms, including the large number of households headed by single parents. The one goal on which everyone can agree is the need to promote policies that will stabilize the global headcount.

  5. Magnetic Resonance Imaging (MRI) -- Head

    Medline Plus

    Full Text Available ... digital cloud server. Currently, MRI is the most sensitive imaging test of the head (particularly the brain) ... Society of Urogenital Radiology note that the available data suggest that it is safe to continue breastfeeding ...

  6. Magnetic Resonance Imaging (MRI) -- Head

    Medline Plus

    Full Text Available ... medically necessary. MRI may not always distinguish between cancer tissue and fluid, known as edema . MRI typically ... Brain Tumors Radiation Therapy for Head and Neck Cancer Others : American Stroke Association National Stroke Association top ...

  7. Magnetic Resonance Imaging (MRI) -- Head

    Medline Plus

    Full Text Available ... a computer to produce detailed pictures of the brain and other cranial structures that are clearer and ... sensitive imaging test of the head (particularly the brain) in routine clinical practice. top of page What ...

  8. Magnetic Resonance Imaging (MRI) -- Head

    Medline Plus

    Full Text Available ... of the head (particularly the brain) in routine clinical practice. top of page What are some common ... acutely injured; however, this decision is based on clinical judgment. This is because traction devices and many ...

  9. Magnetic Resonance Imaging (MRI) -- Head

    Medline Plus

    Full Text Available ... MRI scanners are air-conditioned and well-lit. Music may be played through the headphones to help ... page Additional Information and Resources RTAnswers.org : Radiation Therapy for Brain Tumors Radiation Therapy for Head and ...

  10. Magnetic Resonance Imaging (MRI) -- Head

    Medline Plus

    Full Text Available ... an IV line, into a vein in your hand or arm. A saline solution may be used ... Tumor Treatment Magnetic Resonance Imaging (MRI) Safety Alzheimer's Disease Head Injury Brain Tumors Images related to Magnetic ...

  11. Magnetic Resonance Imaging (MRI) -- Head

    Medline Plus

    Full Text Available ... Videos About Us News Physician Resources Professions Site Index A-Z Magnetic Resonance Imaging (MRI) - Head Magnetic ... very early stage by mapping the motion of water molecules in the tissue. This water motion, known ...

  12. Magnetic Resonance Imaging (MRI) -- Head

    Medline Plus

    Full Text Available ... practice. top of page What are some common uses of the procedure? MR imaging of the head ... gadolinium contrast, it may still be possible to use it after appropriate pre-medication. Patient consent will ...

  13. Magnetic Resonance Imaging (MRI) -- Head

    Medline Plus

    Full Text Available ... MRI) of the head uses a powerful magnetic field, radio waves and a computer to produce detailed ... there’s a possibility you are pregnant. The magnetic field is not harmful, but it may cause some ...

  14. Head, Neck, and Oral Cancer

    Science.gov (United States)

    ... cancer of the head, neck and mouth. The Oral Cancer Foundation estimates that close to 42,000 Americans ... diagnosed with oral or pharyngeal cancer this year. Oral cancer’s mortality is particularly high, not because it is ...

  15. Magnetic Resonance Imaging (MRI) -- Head

    Medline Plus

    Full Text Available ... have a personal story about radiology? Share your patient story here Images ... (fMRI) - Brain Head and Neck Cancer Treatment Brain Tumor Treatment Magnetic Resonance Imaging (MRI) ...

  16. Magnetic Resonance Imaging (MRI) -- Head

    Medline Plus

    Full Text Available ... is not harmful, but it may cause some medical devices to malfunction. Most orthopedic implants pose no ... Head? Magnetic resonance imaging (MRI) is a noninvasive medical test that physicians use to diagnose medical conditions. ...

  17. Magnetic Resonance Imaging (MRI) -- Head

    Medline Plus

    Full Text Available ... the same effect. A very irregular heartbeat may affect the quality of images obtained using techniques that ... Tumor Treatment Magnetic Resonance Imaging (MRI) Safety Alzheimer's Disease Head Injury Brain Tumors Images related to Magnetic ...

  18. Magnetic Resonance Imaging (MRI) -- Head

    Medline Plus

    Full Text Available ... test of the head (particularly the brain) in routine clinical practice. top of page What are some ... told otherwise, you may follow your regular daily routine and take food and medications as usual. Some ...

  19. Eye-based head gestures

    DEFF Research Database (Denmark)

    Mardanbegi, Diako; Witzner Hansen, Dan; Pederson, Thomas

    2012-01-01

    A novel method for video-based head gesture recognition using eye information by an eye tracker has been proposed. The method uses a combination of gaze and eye movement to infer head gestures. Compared to other gesture-based methods a major advantage of the method is that the user keeps the gaze...... on the interaction object while interacting. This method has been implemented on a head-mounted eye tracker for detecting a set of predefined head gestures. The accuracy of the gesture classifier is evaluated and verified for gaze-based interaction in applications intended for both large public displays and small...... mobile phone screens. The user study shows that the method detects a set of defined gestures reliably....

  20. Magnetic Resonance Imaging (MRI) -- Head

    Medline Plus

    Full Text Available ... the same effect. A very irregular heartbeat may affect the quality of images obtained using techniques that ... Information and Resources RTAnswers.org : Radiation Therapy for Brain Tumors Radiation Therapy for Head and Neck Cancer ...

  1. Magnetic Resonance Imaging (MRI) -- Head

    Medline Plus

    Full Text Available ... a CD or uploaded to a digital cloud server. Currently, MRI is the most sensitive imaging test ... Brain Tumor Treatment Magnetic Resonance Imaging (MRI) Safety Alzheimer's Disease Head Injury Brain Tumors Images related to Magnetic ...

  2. Magnetic Resonance Imaging (MRI) -- Head

    Medline Plus

    Full Text Available ... the same effect. A very irregular heartbeat may affect the quality of images obtained using techniques that ... Brain Tumor Treatment Magnetic Resonance Imaging (MRI) Safety Alzheimer's Disease Head Injury Brain Tumors Images related to ...

  3. Magnetic Resonance Imaging (MRI) -- Head

    Medline Plus

    Full Text Available ... Radiation Therapy for Head and Neck Cancer Others : American Stroke Association National Stroke Association top of page ... and is further reviewed by committees from the American College of Radiology (ACR) and the Radiological Society ...

  4. Magnetic Resonance Imaging (MRI) -- Head

    Medline Plus

    Full Text Available ... the head uses a powerful magnetic field, radio waves and a computer to produce detailed pictures of ... the body being imaged, send and receive radio waves, producing signals that are detected by the coils. ...

  5. Magnetic Resonance Imaging (MRI) -- Head

    Medline Plus

    Full Text Available ... data suggest that it is safe to continue breastfeeding after receiving intravenous contrast. For further information please ... Magnetic Resonance Imaging (MRI) Safety Alzheimer's Disease Head Injury Brain Tumors Images related to Magnetic Resonance Imaging ( ...

  6. Magnetic Resonance Imaging (MRI) -- Head

    Medline Plus

    Full Text Available ... scanner. top of page How does the procedure work? Unlike conventional x-ray examinations and computed tomography ( ... for Head and Neck Cancer Others : American Stroke Association National Stroke Association top of page This page ...

  7. Magnetic Resonance Imaging (MRI) -- Head

    Medline Plus

    Full Text Available ... copied to a CD or uploaded to a digital cloud server. Currently, MRI is the most sensitive ... Brain Tumor Treatment Magnetic Resonance Imaging (MRI) Safety Alzheimer's Disease Head Injury Brain Tumors Images related to Magnetic ...

  8. Magnetic Resonance Imaging (MRI) -- Head

    Medline Plus

    Full Text Available ... of the head uses a powerful magnetic field, radio waves and a computer to produce detailed pictures ... medical conditions. MRI uses a powerful magnetic field, radio frequency pulses and a computer to produce detailed ...

  9. Magnetic Resonance Imaging (MRI) -- Head

    Medline Plus

    Full Text Available ... or headphones during the exam. MRI scanners are air-conditioned and well-lit. Music may be played ... the limitations of MRI of the Head? High-quality images are assured only if you are able ...

  10. Magnetic Resonance Imaging (MRI) -- Head

    Medline Plus

    Full Text Available ... may sense a temporary metallic taste in their mouth after the contrast injection. If you do not ... Magnetic Resonance Imaging (MRI) Safety Alzheimer's Disease Head Injury Brain Tumors Images related to Magnetic Resonance Imaging ( ...

  11. Magnetic Resonance Imaging (MRI) -- Head

    Medline Plus

    Full Text Available ... and may add approximately 15 minutes to the total exam time. top of page What will I ... the limitations of MRI of the Head? High-quality images are assured only if you are able ...

  12. Head and Neck Cancer Pain.

    Science.gov (United States)

    Ing, Jakun W

    2017-08-01

    Pain is a significant morbidity resulting from head and neck cancer. Pain may also be the result of the treatments directed against head and neck cancer. An experienced practitioner may manage this pain by understanding the multifactorial mechanisms of pain and the various pharmacotherapies available. Pain should be managed with multiple medications in a multimodal approach, and nonpharmacologic therapies should be considered as well. Copyright © 2017 Elsevier Inc. All rights reserved.

  13. 49 CFR 572.182 - Head assembly.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 7 2010-10-01 2010-10-01 false Head assembly. 572.182 Section 572.182... Dummy, 50th Percentile Adult Male § 572.182 Head assembly. (a) The head assembly consists of the head... assembly shall meet performance requirements specified in paragraph (c) of this section. (b) Test procedure...

  14. Heading for a fall? Management of head injury in infants.

    LENUS (Irish Health Repository)

    Williamson, M

    2010-09-01

    Head injury is one of the commonest reasons for infants (< 1 year) to attend the Emergency Department (ED). Clinical management varies considerably and concern about non accidental injury results in a high admission rate in some hospitals. Information was obtained on 103 children under one year of age presenting to the ED with head injury in a prospective study. The average age was 6.7 months and 57% of patients were male. Twenty eight babies had skull x rays with 1 skull fracture diagnosed. None required CT brain scan. Ninety eight (94%) were discharged home from the ED. There were no unplanned returns, readmissions or adverse events. The incidence of traumatic brain injury in children under one year of age presenting with head injury is low and the majority can be safely discharged home.

  15. Magnetic head having a wear-resistant layer, and method of manufacturing such a magnetic head

    NARCIS (Netherlands)

    Dirne, F.W.A.; Zieren, V.; Broese van Groenou, A.; Oorschot, L.F.M. van; Lasinski, P.; Jongh, M. de; Roozeboom, F.

    2002-01-01

    Magnetic head having a head face (5) and comprising a head structure composed of thin layers and provided with a transducing element (E11), in which different materials occurring in different areas are present in the head face. The head face is provided with a first layer (31) of a material which is

  16. Wheelchair control by head motion

    Directory of Open Access Journals (Sweden)

    Pajkanović Aleksandar

    2013-01-01

    Full Text Available Electric wheelchairs are designed to aid paraplegics. Unfortunately, these can not be used by persons with higher degree of impairment, such as quadriplegics, i.e. persons that, due to age or illness, can not move any of the body parts, except of the head. Medical devices designed to help them are very complicated, rare and expensive. In this paper a microcontroller system that enables standard electric wheelchair control by head motion is presented. The system comprises electronic and mechanic components. A novel head motion recognition technique based on accelerometer data processing is designed. The wheelchair joystick is controlled by the system’s mechanical actuator. The system can be used with several different types of standard electric wheelchairs. It is tested and verified through an experiment performed within this paper.

  17. OCULAR MANIFESTATIONS OF HEAD INJURIES

    Directory of Open Access Journals (Sweden)

    Kanukollu Venkata Madusudana Rao

    2016-12-01

    Full Text Available BACKGROUND This prospective study aimed to evaluate the incidence of ocular manifestations in head injury and their correlation with the intracranial lesions. MATERIALS AND METHODS A total of 108 consecutive cases of closed head injury admitted in the neurosurgical ward of a tertiary teaching hospital underwent a thorough ophthalmic assessment. Clinical examination, radiological imaging and Glasgow Coma Scale (GCS were applied to grade the severity of injury. RESULTS Total number of 108 patients of head injury were examined of which 38 patients had ocular manifestations (35.18%. Of these, 85.18% were males, 84% of injuries were due to road traffic accidents and 16% were due to fall from a height. The ocular manifestations were as follows- Orbital complications were seen in 6 patients (15.8%. Anterior segment manifestations included black eyes seen in 10 patients (26.3%, subconjunctival haemorrhage in 10.5% of patients (4 patients, corneal involvement in 21% of patients (8 patients and pupillary involvement in 50% of patients (19 patients. Posterior segment manifestations were seen in 26.3% of patients (10 patients and were as follows- Purtscher’s retinopathy in 2 patients and optic atrophy in 5 patients. Cranial nerve palsies were seen in 15 patients (39.47% and supranuclear movement disorders were seen in 3 patients (8%. CONCLUSION Even though, neurosurgeons perform comprehensive clinical examination including eye examination, the main purpose is limited to aid topical diagnosis of neurological lesions. This study emphasises the importance of a detailed eye examination by an ophthalmologist to prevent irreversible visual loss in addition to aiding in the neurological diagnosis. Pupillary involvement, papilloedema and ocular motor paresis pointed to a more severe head injury. This observational prospective study helped us to correlate the severity of head injuries in association with ocular findings in patients admitted in neurosurgical ward

  18. Biomimetic Multispiked Connecting Ti-Alloy Scaffold Prototype for Entirely-Cementless Resurfacing Arthroplasty Endoprostheses—Exemplary Results of Implantation of the Ca-P Surface-Modified Scaffold Prototypes in Animal Model and Osteoblast Culture Evaluation

    Directory of Open Access Journals (Sweden)

    Ryszard Uklejewski

    2016-06-01

    Full Text Available We present here—designed, manufactured, and tested by our research team—the Ti-alloy prototype of the multispiked connecting scaffold (MSC-Scaffold interfacing the components of resurfacing arthroplasty (RA endoprostheses with bone. The spikes of the MSC-Scaffold prototype mimic the interdigitations of the articular subchondral bone, which is the natural biostructure interfacing the articular cartilage with the periarticular trabecular bone. To enhance the osteoinduction/osteointegration potential of the MSC-Scaffold, the attempts to modify its bone contacting surfaces by the process of electrochemical cathodic deposition of Ca-P was performed with further immersion of the MSC-Scaffold prototypes in SBF in order to transform the amorphous calcium-phosphate coating in hydroxyapatite-like (HA-like coating. The pilot experimental study of biointegration of unmodified and Ca-P surface-modified MSC-Scaffold prototypes was conducted in an animal model (swine and in osteoblast cell culture. On the basis of a microscope-histological method the biointegration was proven by the presence of trabeculae in the interspike spaces of the MSC-Scaffold prototype on longitudinal and cross-sections of bone-implant specimens. The percentage of trabeculae in the area between the spikes of specimen containing Ca-P surface modified scaffold prototype observed in microCT reconstructions of the explanted joints was visibly higher than in the case of unmodified MSC-Scaffold prototypes. Significantly higher Alkaline Phosphatase (ALP activity and the cellular proliferation in the case of Ca-P-modified MSC-Scaffold pre-prototypes, in comparison with unmodified pre-prototypes, was found in osteoblast cell cultures. The obtained results of experimental implantation in an animal model and osteoblast cell culture evaluations of Ca-P surface-modified and non-modified biomimetic MSC-Scaffold prototypes for biomimetic entirely-cementless RA endoprostheses indicate the

  19. Biomimetic Multispiked Connecting Ti-Alloy Scaffold Prototype for Entirely-Cementless Resurfacing Arthroplasty Endoprostheses-Exemplary Results of Implantation of the Ca-P Surface-Modified Scaffold Prototypes in Animal Model and Osteoblast Culture Evaluation.

    Science.gov (United States)

    Uklejewski, Ryszard; Rogala, Piotr; Winiecki, Mariusz; Tokłowicz, Renata; Ruszkowski, Piotr; Wołuń-Cholewa, Maria

    2016-06-29

    We present here-designed, manufactured, and tested by our research team-the Ti-alloy prototype of the multispiked connecting scaffold (MSC-Scaffold) interfacing the components of resurfacing arthroplasty (RA) endoprostheses with bone. The spikes of the MSC-Scaffold prototype mimic the interdigitations of the articular subchondral bone, which is the natural biostructure interfacing the articular cartilage with the periarticular trabecular bone. To enhance the osteoinduction/osteointegration potential of the MSC-Scaffold, the attempts to modify its bone contacting surfaces by the process of electrochemical cathodic deposition of Ca-P was performed with further immersion of the MSC-Scaffold prototypes in SBF in order to transform the amorphous calcium-phosphate coating in hydroxyapatite-like (HA-like) coating. The pilot experimental study of biointegration of unmodified and Ca-P surface-modified MSC-Scaffold prototypes was conducted in an animal model (swine) and in osteoblast cell culture. On the basis of a microscope-histological method the biointegration was proven by the presence of trabeculae in the interspike spaces of the MSC-Scaffold prototype on longitudinal and cross-sections of bone-implant specimens. The percentage of trabeculae in the area between the spikes of specimen containing Ca-P surface modified scaffold prototype observed in microCT reconstructions of the explanted joints was visibly higher than in the case of unmodified MSC-Scaffold prototypes. Significantly higher Alkaline Phosphatase (ALP) activity and the cellular proliferation in the case of Ca-P-modified MSC-Scaffold pre-prototypes, in comparison with unmodified pre-prototypes, was found in osteoblast cell cultures. The obtained results of experimental implantation in an animal model and osteoblast cell culture evaluations of Ca-P surface-modified and non-modified biomimetic MSC-Scaffold prototypes for biomimetic entirely-cementless RA endoprostheses indicate the enhancement of the

  20. Biomimetic Multispiked Connecting Ti-Alloy Scaffold Prototype for Entirely-Cementless Resurfacing Arthroplasty Endoprostheses—Exemplary Results of Implantation of the Ca-P Surface-Modified Scaffold Prototypes in Animal Model and Osteoblast Culture Evaluation

    Science.gov (United States)

    Uklejewski, Ryszard; Rogala, Piotr; Winiecki, Mariusz; Tokłowicz, Renata; Ruszkowski, Piotr; Wołuń-Cholewa, Maria

    2016-01-01

    We present here—designed, manufactured, and tested by our research team—the Ti-alloy prototype of the multispiked connecting scaffold (MSC-Scaffold) interfacing the components of resurfacing arthroplasty (RA) endoprostheses with bone. The spikes of the MSC-Scaffold prototype mimic the interdigitations of the articular subchondral bone, which is the natural biostructure interfacing the articular cartilage with the periarticular trabecular bone. To enhance the osteoinduction/osteointegration potential of the MSC-Scaffold, the attempts to modify its bone contacting surfaces by the process of electrochemical cathodic deposition of Ca-P was performed with further immersion of the MSC-Scaffold prototypes in SBF in order to transform the amorphous calcium-phosphate coating in hydroxyapatite-like (HA-like) coating. The pilot experimental study of biointegration of unmodified and Ca-P surface-modified MSC-Scaffold prototypes was conducted in an animal model (swine) and in osteoblast cell culture. On the basis of a microscope-histological method the biointegration was proven by the presence of trabeculae in the interspike spaces of the MSC-Scaffold prototype on longitudinal and cross-sections of bone-implant specimens. The percentage of trabeculae in the area between the spikes of specimen containing Ca-P surface modified scaffold prototype observed in microCT reconstructions of the explanted joints was visibly higher than in the case of unmodified MSC-Scaffold prototypes. Significantly higher Alkaline Phosphatase (ALP) activity and the cellular proliferation in the case of Ca-P-modified MSC-Scaffold pre-prototypes, in comparison with unmodified pre-prototypes, was found in osteoblast cell cultures. The obtained results of experimental implantation in an animal model and osteoblast cell culture evaluations of Ca-P surface-modified and non-modified biomimetic MSC-Scaffold prototypes for biomimetic entirely-cementless RA endoprostheses indicate the enhancement of the

  1. The Video Head Impulse Test

    Science.gov (United States)

    Halmagyi, G. M.; Chen, Luke; MacDougall, Hamish G.; Weber, Konrad P.; McGarvie, Leigh A.; Curthoys, Ian S.

    2017-01-01

    In 1988, we introduced impulsive testing of semicircular canal (SCC) function measured with scleral search coils and showed that it could accurately and reliably detect impaired function even of a single lateral canal. Later we showed that it was also possible to test individual vertical canal function in peripheral and also in central vestibular disorders and proposed a physiological mechanism for why this might be so. For the next 20 years, between 1988 and 2008, impulsive testing of individual SCC function could only be accurately done by a few aficionados with the time and money to support scleral search-coil systems—an expensive, complicated and cumbersome, semi-invasive technique that never made the transition from the research lab to the dizzy clinic. Then, in 2009 and 2013, we introduced a video method of testing function of each of the six canals individually. Since 2009, the method has been taken up by most dizzy clinics around the world, with now close to 100 refereed articles in PubMed. In many dizzy clinics around the world, video Head Impulse Testing has supplanted caloric testing as the initial and in some cases the final test of choice in patients with suspected vestibular disorders. Here, we consider seven current, interesting, and controversial aspects of video Head Impulse Testing: (1) introduction to the test; (2) the progress from the head impulse protocol (HIMPs) to the new variant—suppression head impulse protocol (SHIMPs); (3) the physiological basis for head impulse testing; (4) practical aspects and potential pitfalls of video head impulse testing; (5) problems of vestibulo-ocular reflex gain calculations; (6) head impulse testing in central vestibular disorders; and (7) to stay right up-to-date—new clinical disease patterns emerging from video head impulse testing. With thanks and appreciation we dedicate this article to our friend, colleague, and mentor, Dr Bernard Cohen of Mount Sinai Medical School, New York, who since his

  2. The Video Head Impulse Test

    Directory of Open Access Journals (Sweden)

    G. M. Halmagyi

    2017-06-01

    Full Text Available In 1988, we introduced impulsive testing of semicircular canal (SCC function measured with scleral search coils and showed that it could accurately and reliably detect impaired function even of a single lateral canal. Later we showed that it was also possible to test individual vertical canal function in peripheral and also in central vestibular disorders and proposed a physiological mechanism for why this might be so. For the next 20 years, between 1988 and 2008, impulsive testing of individual SCC function could only be accurately done by a few aficionados with the time and money to support scleral search-coil systems—an expensive, complicated and cumbersome, semi-invasive technique that never made the transition from the research lab to the dizzy clinic. Then, in 2009 and 2013, we introduced a video method of testing function of each of the six canals individually. Since 2009, the method has been taken up by most dizzy clinics around the world, with now close to 100 refereed articles in PubMed. In many dizzy clinics around the world, video Head Impulse Testing has supplanted caloric testing as the initial and in some cases the final test of choice in patients with suspected vestibular disorders. Here, we consider seven current, interesting, and controversial aspects of video Head Impulse Testing: (1 introduction to the test; (2 the progress from the head impulse protocol (HIMPs to the new variant—suppression head impulse protocol (SHIMPs; (3 the physiological basis for head impulse testing; (4 practical aspects and potential pitfalls of video head impulse testing; (5 problems of vestibulo-ocular reflex gain calculations; (6 head impulse testing in central vestibular disorders; and (7 to stay right up-to-date—new clinical disease patterns emerging from video head impulse testing. With thanks and appreciation we dedicate this article to our friend, colleague, and mentor, Dr Bernard Cohen of Mount Sinai Medical School, New York, who

  3. Femoral Head and Neck Excision.

    Science.gov (United States)

    Harper, Tisha A M

    2017-07-01

    Femoral head and neck excision is a surgical procedure that is commonly performed in small animal patients. It is a salvage procedure that is done to relieve pain in the coxofemoral joint and restore acceptable function of the limb. Femoral head and neck excision is most commonly used to treat severe osteoarthritis in the coxofemoral joint and can be done in dogs and cats of any size or age. The procedure should not be overused and ideally should not be done when the integrity of the coxofemoral joint can be restored. Copyright © 2017 Elsevier Inc. All rights reserved.

  4. Head First 2D Geometry

    CERN Document Server

    Fallow), Stray

    2009-01-01

    Having trouble with geometry? Do Pi, The Pythagorean Theorem, and angle calculations just make your head spin? Relax. With Head First 2D Geometry, you'll master everything from triangles, quads and polygons to the time-saving secrets of similar and congruent angles -- and it'll be quick, painless, and fun. Through entertaining stories and practical examples from the world around you, this book takes you beyond boring problems. You'll actually use what you learn to make real-life decisions, like using angles and parallel lines to crack a mysterious CSI case. Put geometry to work for you, and

  5. Sex differences in head acceleration during heading while wearing soccer headgear

    National Research Council Canada - National Science Library

    Tierney, Ryan T; Higgins, Michael; Caswell, Shane V; Brady, Jessica; McHardy, Krista; Driban, Jeffrey B; Darvish, Kurosh

    2008-01-01

    .... Soccer headgear is marketed for reducing head acceleration and risk of concussion. To determine the effect of sex and soccer headgear on head impact kinematics and dynamic stabilization during soccer heading...

  6. Magnetic Resonance Imaging (MRI) -- Head

    Medline Plus

    Full Text Available ... very early stage by mapping the motion of water molecules in the tissue. This water motion, known as diffusion, is impaired by most ... page Additional Information and Resources RTAnswers.org : Radiation Therapy for Brain Tumors Radiation Therapy for Head and ...

  7. Magnetic Resonance Imaging (MRI) -- Head

    Medline Plus

    Full Text Available ... data suggest that it is safe to continue breastfeeding after receiving intravenous contrast. For further information please consult the ACR Manual on Contrast Media and its references. top of page What are the limitations of MRI of the Head? High-quality images are assured only if you are able ...

  8. Magnetic Resonance Imaging (MRI) -- Head

    Medline Plus

    Full Text Available ... very early stage by mapping the motion of water molecules in the tissue. This water motion, known as diffusion, is impaired by most ... the limitations of MRI of the Head? High-quality images are assured only if you are able ...

  9. The head organizer in Hydra.

    Science.gov (United States)

    Bode, Hans R

    2012-01-01

    Organizers and organizing centers play critical roles in axis formation and patterning during the early stages of embryogenesis in many bilaterians. The presence and activity of an organizer was first described in adult Hydra about 100 years ago, and in the following decades organizer regions were identified in a number of bilaterian embryos. In an adult Hydra, the cells of the body column are constantly in the mitotic cycle resulting in continuous displacement of the tissue to the extremities where it is sloughed. In this context, the head organizer located in the hypostome is continuously active sending out signals to maintain the structure and morphology of the head, body column and foot of the animal. The molecular basis of the head organizer involves the canonical Wnt pathway, which acts in a self-renewing manner to maintain itself in the context of the tissue dynamics of Hydra. During bud formation, Hydra's mode of asexual reproduction, a head organizer based on the canonical Wnt pathway is set up to initiate and control the development of a new Hydra. As this pathway plays a central role in vertebrate embryonic organizers, its presence and activity in Hydra indicate that the molecular basis of the organizer arose early in metazoan evolution.

  10. Blunt Head Trauma and Headache

    Directory of Open Access Journals (Sweden)

    Ana B Chelse

    2015-04-01

    Full Text Available Investigators from New York Presbyterian Morgan Stanley Children’s Hospital examined whether having an isolated headache following minor blunt head trauma was suggestive of traumatic brain injury (TBI among a large cohort of children 2-18 years of age.

  11. challenges facing child headed households

    African Journals Online (AJOL)

    Mugumbate

    care approaches on psychosocial wellbeing of orphans and other vulnerable children (OVC) in Zimbabwe, ... related stigma, poverty or anomie, are insufficient for understanding the isolation of the child-headed ..... organisation was failing to cope with the problems of these families. This was so because it did not have.

  12. Magnetic Resonance Imaging (MRI) -- Head

    Medline Plus

    Full Text Available ... have special pediatric considerations. The teddy bear denotes child-specific content. Related Articles and Media MR Angiography (MRA) Magnetic Resonance, Functional (fMRI) - Brain Head and Neck Cancer Treatment Brain Tumor Treatment Magnetic Resonance Imaging (MRI) ...

  13. Magnetic Resonance Imaging (MRI) -- Head

    Medline Plus

    Full Text Available ... the head uses a powerful magnetic field, radio waves and a computer to produce detailed pictures of the brain and other cranial structures that are clearer and more detailed than other imaging methods. This exam does not use ionizing radiation and may require an injection of a ...

  14. Magnetic Resonance Imaging (MRI) -- Head

    Medline Plus

    Full Text Available ... examination poses almost no risk to the average patient when appropriate safety guidelines are followed. If sedation is used, there ... have a personal story about radiology? Share your patient story here Images ... Disease Head Injury Brain Tumors Images related ...

  15. Magnetic Resonance Imaging (MRI) -- Head

    Medline Plus

    Full Text Available ... of which shows a thin slice of the body. The images can then be studied from different angles by ... information please consult the ACR Manual on Contrast Media and its references. top of page What are the limitations of MRI of the Head? High-quality images are assured only if you are able to ...

  16. Magnetic Resonance Imaging (MRI) -- Head

    Medline Plus

    Full Text Available ... symptoms. It can help diagnose conditions such as: brain tumors stroke infections developmental anomalies hydrocephalus — dilatation of fluid ... Information and Resources RTAnswers.org : Radiation Therapy for Brain Tumors Radiation Therapy for Head and Neck Cancer Others : ...

  17. Femoral head cartilage disarticulation disorder

    Science.gov (United States)

    Femoral head cartilage disarticulation disorder and necrosis is a major skeletal problem in broiler breeders since they are maintained for a long time in the farm. The etiology of this disease is not well understood. A field study was conducted to understand the basis of this metabolic disease. Six ...

  18. Magnetic Resonance Imaging (MRI) -- Head

    Medline Plus

    Full Text Available ... structures of the brain and can also provide functional information (fMRI) in selected cases. MR images of ... Articles and Media MR Angiography (MRA) Magnetic Resonance, Functional (fMRI) - Brain Head and Neck Cancer Treatment Brain ...

  19. Magnetic Resonance Imaging (MRI) -- Head

    Medline Plus

    Full Text Available ... imaging (MRI) of the head uses a powerful magnetic field, radio waves and a computer to produce detailed ... whether there’s a possibility you are pregnant. The magnetic field is not harmful, but it may cause some ...

  20. Humeral head size in shoulder arthroplasty

    DEFF Research Database (Denmark)

    Vaesel, M T; Olsen, Bo Sanderhoff; Søjbjerg, Jens Ole

    1998-01-01

    Changes in kinematics after hemiarthroplasty of the glenohumeral joint were investigated in nine cadaveric specimens. During experiments the influence of the humeral head size on glenohumeral kinematics was evaluated. A modular prosthesis with five different head sizes and press-fit stems was used....... Three-dimensional kinematic measurements during abduction and adduction from 0 degree to 70 degrees showed increased external rotation with increasing head size. Small prosthetic heads translated inferiorly and large prosthetic heads superiorly compared with the intact humeral head. During forced...

  1. Radial head prosthesis: results overview.

    Science.gov (United States)

    Carità, E; Donadelli, A; Cugola, L; Perazzini, P

    2017-12-01

    Radial head replacement is frequently used in treatment of radial head fractures or sequela. Impossibility to restore a correct anatomy, acute elbow traumatic instability and failure of osteosynthesis hardware are the most common indications. The authors describe their case studies and results on the implantation of various radial head prostheses. Between June 2005 and June 2016, 28 radial head prostheses were implanted in the same number of patients with an average follow-up of 49 months (6-104). Indications for implantation were: Mason type III and IV radial head fractures and post-traumatic arthritis due to failure of previous treatments. Monopolar prostheses were used and were press-fit implanted via Kaplan's lateral access and Kocher's anconeus approach to the humeroradial joint. At the follow-up, assessments were made of the pain, according to the visual analogic scale, range of motion (ROM), stability and functionality according to the Mayo Elbow Performance Score, presence of osteolysis and mobilization during radiography tests, personal satisfaction of the patients, Disabilities of the Arm, Shoulder and Hand and Patient-Rated Wrist Evaluation outcomes measurements. At the follow-up, we recorded an average level of pain of 1.8 in patients under acute treatments for radial head fractures and a marked reduction in the remaining cases from 6.7 to 2.1. ROM was found on average to be 107° of flexion-extension and 159° of pronosupination. Personal satisfaction was good-excellent in 23 cases. There was no case of infection; removal of the implant was necessary in three cases due to mobilization of the stem and oversized implants. In six cases, bone resorption was seen at the level of the prosthetic collar and it was in all cases asymptomatic. The results of this study suggest that the use of prostheses, if well positioned, is a valid solution in the treatment of secondary arthritis and fractures of the radial head with poor prognosis, with good results in the

  2. Porcine head response to blast

    Directory of Open Access Journals (Sweden)

    Jay eShridharani

    2012-05-01

    Full Text Available Recent studies have shown an increase in the frequency of traumatic brain injuries related to blast exposure. However, the mechanisms that cause blast neurotrauma are unknown. Blast neurotrauma research using computational models has been one method to elucidate that response of the brain in blast, and to identify possible mechanical correlates of injury. However, model validation against experimental data is required to ensure that the model output is representative of in vivo biomechanical response. This study exposed porcine subjects to primary blast overpressures generated using a compressed-gas shock tube. Shock tube blasts were directed to the unprotected head of each animal while the lungs and thorax were protected using ballistic protective vests similar to those employed in theater. The test conditions ranged from 110-740 kPa peak incident overpressure with scaled durations from 1.3-6.9 ms and correspond approximately with a 50% injury risk for brain bleeding and apnea in a ferret model scaled to porcine exposure. The bulk head acceleration and the pressure at the surface of the head and in the cranial cavity were measured. Immediately after the blast, 5 of the 20 animals tested were apneic. Three subjects recovered without intervention within thirty seconds and the remaining two recovered within 8 minutes following bagging and administration of the respiratory stimulant doxapram. Gross examination of the brain revealed no indication of bleeding. Intracranial pressures ranged from 80-685 kPa as a result of the blast and were notably lower than the shock tube reflected pressures of 300-2830 kPa, indicating pressure attenuation by the skull up to a factor of 8.4. Peak head accelerations were measured from 385-3845 G’s and were well correlated with peak incident overpressure (R2=0.90. One standard deviation corridors for the surface pressure, intracranial pressure, and head acceleration are presented to provide experimental data for

  3. Preschool Facilities - MDC_HeadStart

    Data.gov (United States)

    NSGIC Local Govt | GIS Inventory — A label (point) feature class of Head Start / Early Head Start/ Delegate Agencies/ Child Care Partnership & Family Day Care Homes Programs location in Miami-Dade...

  4. Heads Up: Concussion in Youth Sports

    Medline Plus

    Full Text Available ... What's this? Submit What's this? Submit Button Concussion in Youth Sports Training course: This page has moved ... What's this? Submit What's this? Submit Button Connect with HEADS UP & CDC's Injury Center HEADS UP Resources ...

  5. Heads Up: Concussion in Youth Sports

    Medline Plus

    Full Text Available ... this? Submit Button Connect with HEADS UP & CDC's Injury Center HEADS UP Resources File Formats Help: How ... for Disease Control and Prevention , National Center for Injury Prevention and Control , Division of Unintentional Injury Prevention ...

  6. Heads Up to High School Sports

    Science.gov (United States)

    ... submit" value="Submit" /> HEADS UP to School Sports Recommend on Facebook Tweet Share Compartir To help ... organizations, developed the HEADS UP: Concussion in School Sports initiative and materials. Specific Concussion Information for... Coaches ...

  7. Adjustment of saccade characteristics during head movements.

    Science.gov (United States)

    Morasso, P.; Bizzi, E.; Dichgans, J.

    1973-01-01

    Saccade characteristics have been studied during coordinated eye-head movements in monkeys. Amplitude, duration, and peak velocity of saccades with head turning were compared with saccades executed while the head was artificially restrained. The results indicate that the saccade characteristics are modulated as a function of head movement, hence the gaze movement (eye+head) exactly matches saccades with head fixed. Saccade modulation is achieved by way of negative vestibulo-ocular feedback. The neck proprioceptors, because of their longer latency, are effective only if the head starts moving prior to the onset of saccade. It is concluded that saccades make with head turning are not 'ballistic' movements because their trajectory is not entirely predetermined by a central command.

  8. Head stabilization in whooping cranes

    Science.gov (United States)

    Kinloch, M.R.; Cronin, T.W.; Olsen, G.H.; Chavez-Ramirez, Felipe

    2005-01-01

    The whooping crane (Grus americana) is the tallest bird in North America, yet not much is known about its visual ecology. How these birds overcome their unusual height to identify, locate, track, and capture prey items is not well understood. There have been many studies on head and eye stabilization in large wading birds (herons and egrets), but the pattern of head movement and stabilization during foraging is unclear. Patterns of head movement and stabilization during walking were examined in whooping cranes at Patuxent Wildlife Research Center, Laurel, Maryland USA. Four whooping cranes (1 male and 3 females) were videotaped for this study. All birds were already acclimated to the presence of people and to food rewards. Whooping cranes were videotaped using both digital and Hi-8 Sony video cameras (Sony Corporation, 7-35 Kitashinagawa, 6-Chome, Shinagawa-ku, Tokyo, Japan), placed on a tripod and set at bird height in the cranes' home pens. The cranes were videotaped repeatedly, at different locations in the pens and while walking (or running) at different speeds. Rewards (meal worms, smelt, crickets and corn) were used to entice the cranes to walk across the camera's view plane. The resulting videotape was analyzed at the University of Maryland at Baltimore County. Briefly, we used a computerized reduced graphic model of a crane superimposed over each frame of analyzed tape segments by means of a custom written program (T. W. Cronin, using C++) with the ability to combine video and computer graphic input. The speed of the birds in analyzed segments ranged from 0.30 m/s to 2.64 m/s, and the proportion of time the head was stabilized ranged from 79% to 0%, respectively. The speed at which the proportion reached 0% was 1.83 m/s. The analyses suggest that the proportion of time the head is stable decreases as speed of the bird increases. In all cases, birds were able to reach their target prey with little difficulty. Thus when cranes are walking searching for food

  9. Head Impact Exposure in Collegiate Football Players

    OpenAIRE

    Crisco, Joseph J.; Wilcox, Bethany J.; Beckwith, Jonathan G.; Chu, Jeffrey J.; Duhaime, Ann-Christine; Rowson, Steve; Duma, Stefan M.; Maerlender, Arthur C.; McAllister, Thomas W.; Greenwald, Richard M.

    2011-01-01

    In American football, impacts to the helmet and the resulting head accelerations are the primary cause of concussion injury and potentially chronic brain injury. The purpose of this study was to quantify exposures to impacts to the head (frequency, location and magnitude) for individual collegiate football players and to investigate differences in head impact exposure by player position. A total of 314 players were enrolled at three institutions and 286,636 head impacts were recorded over thr...

  10. Head movements while steering around bends

    NARCIS (Netherlands)

    Erp, J.B.F. van; Oving, A.B.

    2012-01-01

    In this study, the determinants of head motions (rotations) when driving around bends were investigated when drivers viewed the scene through a head-mounted display. The scene camera was either fixed or coupled to head motions along 2 or 3 axes of rotation. Eight participants drove around a

  11. Heads in Grammatical Theory. Introduction.

    OpenAIRE

    Corbett, Greville G.; Fraser, Norman M.; McGlashan, Scott

    1993-01-01

    Contemporary linguistic theories distinguish the principal element of a phrase - the ‘head’ - from the subordinate elements it dominates. This pervasive grammatical concept has been used to describe and account for linguistic phenomena ranging from agreement and government to word order universals, but opinions differ widely on its precise definition. A key question is whether the head is not already identified by some other, more basic notion or interacting set of notions in linguistics. Hea...

  12. Supernumerary head of biceps brachii

    Directory of Open Access Journals (Sweden)

    Balasubramanian A

    2010-12-01

    Full Text Available The biceps brachii muscle and the musculocutaneous nerve of arm are frequent in their variations. A third head of biceps brachii was noted unilaterally during routine anatomy dissection. Variation in musculocutaneous nerve was also seen on the same arm. The evolutionary and functional basis of such variations are discussed. Such variations become relevant during surgical intervention of the arm, especially after humeral fracture with subsequent unusual bone displacements.

  13. Optical Head Design Using HOE's

    Science.gov (United States)

    Ih, Charles S.; Xiang, Lian-Qin; Zhuang, B. H.; Yang, C. W.; Lu, K. Q.; Tian, Rongsheng; Wang, Z. M.

    1989-05-01

    We describe an optical head design using two spherical lenses and two HOE's. This study was intended to show the feasibility of using HOE's to improve the performance of optical head for Read/Write optical disc drives. The two HOE's correct the spherical aberrations of the lens, change the elliptical beam to a circular one and compensate for wavelength shift up to +, - 5 nm. Experiments have been performed to confirm these concepts. The HOE's were made optically in the visible wavelength using an intermediate CGH. Ideally the HOE's are to be generated by a computer and preferably written directly by an e-beam machine. Since at that time all the commercially available e-beam shops we contacted lacked the confidence in making such high resolution CGH, we decided to use the Optical-CGH approach. Actually this approach offers several advantages. First we can make large and high resolution ir HOE immediately. Secondly we can even make Bragg (or volume) ir hologram using visible light. Basically we create a pre-distorted CGH from which the final HOE can be made using visible light. The final HOE can then be reconstruct at the ir wavelength without aberrations. The techniques used here can be extended to optical head designs using aspherical lenses. The HOE's function can then be, in addition to beam shaping, to achieve a larger wavelength compensation, to correct the residual chromatic and aspherical aberrations of the aspherical lenses. The astigmatism of the laser diode can also be corrected by the HOE's. The possibility of an optical head using only HOE's (no lenses) will be discussed. Computer simulations and experimental results are shown.

  14. Cranial surgery without head shaving.

    Science.gov (United States)

    Tokimura, Hiroshi; Tajitsu, Kenichiro; Tsuchiya, Masahiro; Yamahata, Hitoshi; Taniguchi, Ayumi; Takayama, Kenji; Kaji, Masatomo; Hirabaru, Masashi; Hirayama, Takahisa; Shinsato, Tomomi; Arita, Kazunori

    2009-12-01

    Based on a series of 632 patients who underwent craniotomy without head shaving, we report the efficacy and safety of our simplified procedure and document the usefulness of the electrosurgical scalpel. After brushing a chlorhexidine-alcohol solution onto the craniotomy site, the hair was parted from the incision line and fixed with adhesive paper drapes. In recent cases, electrosurgical scalpels were used for scalp- and subcutaneous dissection. At the end of surgery, the wound was closed in the usual manner, taking care that no hair was in the wound and the hair and wound were rinsed with clean water in the operating room. We did not apply disinfectant for postoperative wound care, rather, the hair was shampooed on the 2nd, 4th, and 6th postoperative day. Among 632 patients who underwent cranial surgery without head shaving, only 7 (1.1%) developed postoperative wound infections. None of the 34 patients who underwent craniotomy using the electrosurgical scalpel developed wound infections. Our simplified cranial surgery without head shaving does not increase the risk of wound infection. Because the use of the electrosurgical scalpel for skin and soft tissue dissection minimizes bleeding, the probability of wound infection appears to be reduced.

  15. Is Heading in Youth Soccer Dangerous Play?

    Science.gov (United States)

    O'Kane, John W

    2016-01-01

    Soccer is among the most popular youth sports with over 3 million youth players registered in the U.S. Soccer is unique in that players intentionally use their head to strike the ball, leading to concerns that heading could cause acute or chronic brain injury, especially in the immature brains of children. Pub Med search without date restriction was conducted in November 2014 and August 2015 using the terms soccer and concussion, heading and concussion, and youth soccer and concussion. 310 articles were identified and reviewed for applicable content specifically relating to youth athletes, heading, and/or acute or chronic brain injury from soccer. Soccer is a low-risk sport for catastrophic head injury, but concussions are relatively common and heading often plays a role. At all levels of play, concussions are more likely to occur in the act of heading than with other facets of the game. While concussion from heading the ball without other contact to the head appears rare in adult players, some data suggests children are more susceptible to concussion from heading primarily in game situations. Contributing factors include biomechanical forces, less developed technique, and the immature brain's susceptibility to injury. There is no evidence that heading in youth soccer causes any permanent brain injury and there is limited evidence that heading in youth soccer can cause concussion. A reasonable approach based on U.S. Youth Soccer recommendations is to teach heading after age 10 in controlled settings, and heading in games should be delayed until skill acquisition and physical maturity allow the youth player to head correctly with confidence.

  16. Porcine head response to blast.

    Science.gov (United States)

    Shridharani, Jay K; Wood, Garrett W; Panzer, Matthew B; Capehart, Bruce P; Nyein, Michelle K; Radovitzky, Raul A; Bass, Cameron R 'dale'

    2012-01-01

    Recent studies have shown an increase in the frequency of traumatic brain injuries related to blast exposure. However, the mechanisms that cause blast neurotrauma are unknown. Blast neurotrauma research using computational models has been one method to elucidate that response of the brain in blast, and to identify possible mechanical correlates of injury. However, model validation against experimental data is required to ensure that the model output is representative of in vivo biomechanical response. This study exposes porcine subjects to primary blast overpressures generated using a compressed-gas shock tube. Shock tube blasts were directed to the unprotected head of each animal while the lungs and thorax were protected using ballistic protective vests similar to those employed in theater. The test conditions ranged from 110 to 740 kPa peak incident overpressure with scaled durations from 1.3 to 6.9 ms and correspond approximately with a 50% injury risk for brain bleeding and apnea in a ferret model scaled to porcine exposure. Instrumentation was placed on the porcine head to measure bulk acceleration, pressure at the surface of the head, and pressure inside the cranial cavity. Immediately after the blast, 5 of the 20 animals tested were apneic. Three subjects recovered without intervention within 30 s and the remaining two recovered within 8 min following respiratory assistance and administration of the respiratory stimulant doxapram. Gross examination of the brain revealed no indication of bleeding. Intracranial pressures ranged from 80 to 390 kPa as a result of the blast and were notably lower than the shock tube reflected pressures of 300-2830 kPa, indicating pressure attenuation by the skull up to a factor of 8.4. Peak head accelerations were measured from 385 to 3845 G's and were well correlated with peak incident overpressure (R(2) = 0.90). One SD corridors for the surface pressure, intracranial pressure (ICP), and head acceleration are

  17. First Class Call Stacks: Exploring Head Reduction

    Directory of Open Access Journals (Sweden)

    Philip Johnson-Freyd

    2016-06-01

    Full Text Available Weak-head normalization is inconsistent with functional extensionality in the call-by-name λ-calculus. We explore this problem from a new angle via the conflict between extensionality and effects. Leveraging ideas from work on the λ-calculus with control, we derive and justify alternative operational semantics and a sequence of abstract machines for performing head reduction. Head reduction avoids the problems with weak-head reduction and extensionality, while our operational semantics and associated abstract machines show us how to retain weak-head reduction's ease of implementation.

  18. Mechanisms of head injuries in elite football.

    Science.gov (United States)

    Andersen, T E; Arnason, A; Engebretsen, L; Bahr, R

    2004-12-01

    The aim of this study was to describe, using video analysis, the mechanisms of head injuries and of incidents with a high risk of head injury in elite football. Videotapes and injury information were collected prospectively for 313 of the 409 matches played in the Norwegian (2000 season) and Icelandic (1999 and 2000 season) professional leagues. Video recordings of incidents where a player appeared to be hit in the head and the match was consequently interrupted by the referee were analysed and cross referenced with reports of acute time loss injuries from the team medical staff. The video analysis revealed 192 incidents (18.8 per 1000 player hours). Of the 297 acute injuries reported, 17 (6%) were head injuries, which corresponds to an incidence of 1.7 per 1000 player hours (concussion incidence 0.5 per 1000 player hours). The most common playing action was a heading duel with 112 cases (58%). The body part that hit the injured player's head was the elbow/arm/hand in 79 cases (41%), the head in 62 cases (32%), and the foot in 25 cases (13%). In 67 of the elbow/arm/hand impacts, the upper arm of the player causing the incident was at or above shoulder level, and the arm use was considered to be active in 61 incidents (77%) and intentional in 16 incidents (20%). This study suggests that video analysis provides detailed information about the mechanisms for head injuries in football. The most frequent injury mechanism was elbow to head contact, followed by head to head contact in heading duels. In the majority of the elbow to head incidents, the elbow was used actively at or above shoulder level, and stricter rule enforcement or even changes in the laws of the game concerning elbow use should perhaps be considered, in order to reduce the risk of head injury.

  19. Effects of metal-on-metal wear on the host immune system and infection in hip arthroplasty

    NARCIS (Netherlands)

    Hosman, Anton H.; van der Mei, Henny C.; Bulstra, Sjoerd K.; Busscher, Henk J.; Neut, Danielle

    2010-01-01

    Methods We reviewed the available literature on the influence of degradation products of MOM bearings in total hip arthroplasties on infection risk. Results Wear products were found to influence the risk of infection by hampering the immune system, by inhibiting or accelerating bacterial growth, and

  20. Large diameter metal on metal total hip replacement for femoral neck fractures with neurological conditions A retrospective assessment

    Directory of Open Access Journals (Sweden)

    Jia Li

    2014-01-01

    Conclusion: We believe the use of L-MoM can diminish the rate of instability or dislocation, after operation. The L-MoM is an option for patients with Parkinson′s disease and poliomyelitis with femoral neck fracture.

  1. Head First jQuery

    CERN Document Server

    Benedetti, Ryan

    2011-01-01

    Want to add more interactivity and polish to your websites? Discover how jQuery can help you build complex scripting functionality in just a few lines of code. With Head First jQuery, you'll quickly get up to speed on this amazing JavaScript library by learning how to navigate HTML documents while handling events, effects, callbacks, and animations. By the time you've completed the book, you'll be incorporating Ajax apps, working seamlessly with HTML and CSS, and handling data with PHP, MySQL and JSON. If you want to learn-and understand-how to create interactive web pages, unobtrusive scrip

  2. Head Access Piping System Desing

    OpenAIRE

    中大路 道彦; 一宮 正和; 向坊 隆一; 前田 清彦; 永田 敬

    1994-01-01

    PNC made design studies on loop type FBR plants:a 600 MWe class in '91, and a 1300 MWe class in '93 both with the "head access" primary piping system. This paper focuses on the features of the smaller plant at first and afterwards on the extension to the larger one. The contents of the paper consist of R/V wall protection mechanism, primary piping circuit, secondary piping circuit, plant layout and then, discusses the extension of the applicability of the wall protection mechanism, primary pi...

  3. A Pre-Hispanic Head

    Science.gov (United States)

    Bianucci, Raffaella; Jeziorska, Maria; Lallo, Rudy; Mattutino, Grazia; Massimelli, Massimo; Phillips, Genevieve; Appenzeller, Otto

    2008-01-01

    This report on a male head revealed biologic rhythms, as gleaned from hydrogen isotope ratios in hair, consistent with a South-American origin and Atomic Mass Spectrometry radiocarbon dating (AMS) compatible with the last pre-Hispanic period (1418–1491 AD, 95.4% probability). Biopsies showed exceptionally well-preserved tissues. The hair contained high levels of toxic elements (lead, arsenic and mercury) incompatible with life. There was no evidence for lead deposition in bone consistent with post-mortem accumulation of this toxic element in the hair. We propose that the high content of metals in hair was the result of metabolic activity of bacteria leading to metal complexation in extra cellular polymeric substances (EPS). This is a recognized protective mechanism for bacteria that thrive in toxic environments. This mechanism may account for the tissues preservation and gives a hint at soil composition where the head was presumably buried. Our results have implications for forensic toxicology which has, hitherto, relied on hair analyses as one means to reconstruct pre-mortem metabolism and for detecting toxic elements accumulated during life. Our finding also has implications for other archaeological specimens where similar circumstances may distort the results of toxicological studies. PMID:18446229

  4. Head and neck position sense.

    Science.gov (United States)

    Armstrong, Bridget; McNair, Peter; Taylor, Denise

    2008-01-01

    Traumatic minor cervical strains are common place in high-impact sports (e.g. tackling) and premature degenerative changes have been documented in sports people exposed to recurrent impact trauma (e.g. scrummaging in rugby) or repetitive forces (e.g. Formula 1 racing drivers, jockeys). While proprioceptive exercises have been an integral part of rehabilitation of injuries in the lower limb, they have not featured as prominently in the treatment of cervical injuries. However, head and neck position sense (HNPS) testing and re-training may have relevance in the management of minor sports-related neck injuries, and play a role in reducing the incidence of ongoing pain and problems with function. For efficacious programmes to be developed and tested, fundamental principles associated with proprioception in the cervical spine should be considered. Hence, this article highlights the importance of anatomical structures in the cervical spine responsible for position sense, and how their interaction with the CNS affects our ability to plan and execute effective purposeful movements. This article includes a review of studies examining position sense in subjects with and without pathology and describes the effects of rehabilitation programmes that have sought to improve position sense. In respect to the receptors providing proprioceptive information for the CNS, the high densities and complex arrays of spindles found in cervical muscles suggest that these receptors play a key role. There is some evidence suggesting that ensemble encoding of discharge patterns from muscle spindles is relayed to the CNS and that a pattern recognition system is used to establish joint position and movement. Sensory information from neck proprioceptive receptors is processed in tandem with information from the vestibular system. There are extensive anatomical connections between neck proprioceptive inputs and vestibular inputs. If positional information from the vestibular system is inaccurate or

  5. AHP 47: YELLOW-HEAD HORSE

    Directory of Open Access Journals (Sweden)

    Sangs rgyas bkra shis སངས་རྒྱས་བཀྲ་ཤིས།

    2017-04-01

    Full Text Available My family had a stallion we called Rta mgo ser 'Yellow-Head Horse'. Father and two of his brothers occasionally rode it. Father said that Yellow-Head was very wild when it was taken to join local horseraces. I didn't believe that because Yellow-Head was very gentle when Mother rode it to the local monastery and also when I rode it.

  6. Femoral head diameter in the Malaysian population.

    Science.gov (United States)

    Lee, Chee Kean; Kwan, Mun Keong; Merican, Azhar Mahmood; Ng, Wuey Min; Saw, Lim Beng; Teh, Kok Kheng; Krishnan, Manoharan; Ramiah, Ramanathan

    2014-08-01

    Hip arthroplasty is commonly performed worldwide. The objective of this study was to determine the diameter of the femoral head in the Malaysian population in relation to gender and race (i.e. among Malay, Chinese and Indian patients). This was a retrospective cross-sectional study performed between January 1995 and December 2006, evaluating the femoral head diameters of all patients aged 50 years and above who underwent hemiarthroplasty at two major hospitals in Malaysia. A total of 945 femoral heads (663 women, 282 men) were evaluated. The mean age of the patients in our cohort was 75.2 ± 9.4 (range 50-101) years. The mean femoral head diameter (with intact articular cartilage) was 44.9 ± 3.2 (range 38-54) mm. In our study, men had a significantly larger mean femoral head diameter than women (47.7 ± 2.8 mm vs. 43.7 ± 2.4 mm; p Chinese ethnicity were also found to have significantly larger femoral head diameters, when compared among the three races studied (p Malaysians have a mean femoral head diameter of 44.9 ± 3.2 mm. Among our patients, Chinese patients had a significantly larger femoral head size than Malay and Indian patients. We also found that, in our cohort, men had significantly larger femoral head diameters than women.

  7. Fever in pregnancy and offspring head circumference

    DEFF Research Database (Denmark)

    Dreier, Julie Werenberg; Strandberg-Larsen, Katrine; Uldall, Peter Vilhelm

    2017-01-01

    was ascertained in two interviews during pregnancy and information on head circumference at birth was extracted from the Danish Medical Birth Registry. RESULTS: Fever in pregnancy was reported by 27% of the mothers, and we identified 3370 cases of microcephaly (head circumference less than or equal to third...... percentile for sex and gestational age) and 1140 cases of severe microcephaly (head circumference less than or equal to first percentile for sex and gestational age). In this study, maternal fever exposure was not associated with reduced head circumference (adjusted β = 0.03, 95% confidence intervals [CI]: 0...

  8. Radial head button holing: a cause of irreducible anterior radial head dislocation

    Energy Technology Data Exchange (ETDEWEB)

    Shin, Su-Mi; Chai, Jee Won; You, Ja Yeon; Park, Jina [Seoul National University Seoul Metropolitan Government Boramae Medical Center, Department of Radiology, Seoul (Korea, Republic of); Bae, Kee Jeong [Seoul National University Seoul Metropolitan Government Boramae Medical Center, Department of Orthopedic Surgery, Seoul (Korea, Republic of)

    2016-10-15

    ''Buttonholing'' of the radial head through the anterior joint capsule is a known cause of irreducible anterior radial head dislocation associated with Monteggia injuries in pediatric patients. To the best of our knowledge, no report has described an injury consisting of buttonholing of the radial head through the annular ligament and a simultaneous radial head fracture in an adolescent. In the present case, the radiographic findings were a radial head fracture with anterior dislocation and lack of the anterior fat pad sign. Magnetic resonance imaging (MRI) clearly demonstrated anterior dislocation of the fractured radial head through the torn annular ligament. The anterior joint capsule and proximal portion of the annular ligament were interposed between the radial head and capitellum, preventing closed reduction of the radial head. Familiarity with this condition and imaging findings will aid clinicians to make a proper diagnosis and fast decision to perform an open reduction. (orig.)

  9. Linear and angular head accelerations during heading of a soccer ball

    National Research Council Canada - National Science Library

    Naunheim, Rosanne S; Bayly, Philip V; Standeven, John; Neubauer, Jeremy S; Lewis, Larry M; Genin, Guy M

    2003-01-01

    .... To assess the severity of a single instance of heading a soccer ball, this study experimentally and theoretically evaluated the linear and angular accelerations experienced by the human head during...

  10. Early Outcomes of Primary Total Hip Arthroplasty for Osteonecrosis of the Femoral Head in Patients with Human Immunodeficiency Virus in China

    Directory of Open Access Journals (Sweden)

    Chang-Song Zhao

    2015-01-01

    Full Text Available Background: Studies have reported that patients with human immunodeficiency virus (HIV have a high incidence of osteonecrosis of the femoral head (ONFH. Total hip arthroplasty (THA is an effective management of ONFH. However, little data exist regarding the use of THA for the HIV patients with ONFH in China. This study reviewed the outcomes of HIV-positive patients who underwent THA for ONFH, compared with HIV-negative individuals. Methods: The patients who underwent THA for ONFH from September 2012 to September 2014 in Beijing Ditan Hospital, Capital Medical University were retrospectively studied. Twenty-eight HIV-positive patients and 35 HIV-negative patients underwent 48 THAs and 45 THAs with cementless components, respectively. Medical records and follow-up data were reviewed. Harris Hip Score (HHS was applied to evaluate the pain and function of the hips before and after THA. Complications such as wound healing, surgical site infection, deep venous thrombosis, pulmonary embolism, sepsis, mortality, and complications from the prosthesis were reviewed. The operation time, blood loss, and hospital stay were compared between the two groups. Results: The mean follow-up period was 19.5 ± 5.8 months (ranging from 6 to 30 months. The mean age of the HIV-positive patients with osteonecrosis at the time of surgery was 35 years old, which was significantly lower than that of the HIV-negative group (42 years old (P 0.05. The HHSs of two groups significantly improved after THAs (P < 0.05, without significant difference between two groups. No wound complication, sepsis, mortality, prosthesis complication, and occupational exposure occurred, except for two cases of heterotopic ossification and one case of humeral head necrosis. Conclusions: ONFH is more likely to occur bilaterally in younger HIV-positive males. The development of osteonecrosis seems faster in HIV-positive patients than in HIV-negative patients. This should be cautionary for asymptomatic

  11. Head First WordPress

    CERN Document Server

    Siarto, Jeff

    2010-01-01

    Whether you're promoting your business or writing about your travel adventures, Head First WordPress will teach you not only how to make your blog look unique and attention-grabbing, but also how to dig into the more complex features of WordPress 3.0 to make your website work well, too. You'll learn how to move beyond the standard WordPress look and feel by customizing your blog with your own URL, templates, plugin functionality, and more. As you learn, you'll be working with real WordPress files: The book's website provides pre-fab WordPress themes to download and work with as you follow al

  12. Systematic analysis of head-to-head gene organization: evolutionary conservation and potential biological relevance.

    Directory of Open Access Journals (Sweden)

    Yuan-Yuan Li

    2006-07-01

    Full Text Available Several "head-to-head" (or "bidirectional" gene pairs have been studied in individual experiments, but genome-wide analysis of this gene organization, especially in terms of transcriptional correlation and functional association, is still insufficient. We conducted a systematic investigation of head-to-head gene organization focusing on structural features, evolutionary conservation, expression correlation and functional association. Of the present 1,262, 1,071, and 491 head-to-head pairs identified in human, mouse, and rat genomes, respectively, pairs with 1- to 400-base pair distance between transcription start sites form the majority (62.36%, 64.15%, and 55.19% for human, mouse, and rat,respectively of each dataset, and the largest group is always the one with a transcription start site distance of 101 to 200 base pairs. The phylogenetic analysis among Fugu, chicken, and human indicates a negative selection on the separation of head-to-head genes across vertebrate evolution, and thus the ancestral existence of this gene organization. The expression analysis shows that most of the human head-to-head genes are significantly correlated,and the correlation could be positive, negative, or alternative depending on the experimental conditions. Finally, head to-head genes statistically tend to perform similar functions, and gene pairs associated with the significant cofunctions seem to have stronger expression correlations. The findings indicate that the head-to-head gene organization is ancient and conserved, which subjects functionally related genes to correlated transcriptional regulation and thus provides an exquisite mechanism of transcriptional regulation based on gene organization. These results have significantly expanded the knowledge about head-to-head gene organization. Supplementary materials for this study are available at http://www.scbit.org/h2h.

  13. Reactor vessel lower head integrity

    Energy Technology Data Exchange (ETDEWEB)

    Rubin, A.M.

    1997-02-01

    On March 28, 1979, the Three Mile Island Unit 2 (TMI-2) nuclear power plant underwent a prolonged small break loss-of-coolant accident that resulted in severe damage to the reactor core. Post-accident examinations of the TMI-2 reactor core and lower plenum found that approximately 19,000 kg (19 metric tons) of molten material had relocated onto the lower head of the reactor vessel. Results of the OECD TMI-2 Vessel Investigation Project concluded that a localized hot spot of approximately 1 meter diameter had existed on the lower head. The maximum temperature on the inner surface of the reactor pressure vessel (RPV) in this region reached 1100{degrees}C and remained at that temperature for approximately 30 minutes before cooling occurred. Even under the combined loads of high temperature and high primary system pressure, the TMI-2 RPV did not fail. (i.e. The pressure varied from about 8.5 to 15 MPa during the four-hour period following the relocation of melt to the lower plenum.) Analyses of RPV failure under these conditions, using state-of-the-art computer codes, predicted that the RPV should have failed via local or global creep rupture. However, the vessel did not fail; and it has been hypothesized that rapid cooling of the debris and the vessel wall by water that was present in the lower plenum played an important role in maintaining RPV integrity during the accident. Although the exact mechanism(s) of how such cooling occurs is not known, it has been speculated that cooling in a small gap between the RPV wall and the crust, and/or in cracks within the debris itself, could result in sufficient cooling to maintain RPV integrity. Experimental data are needed to provide the basis to better understand these phenomena and improve models of RPV failure in severe accident codes.

  14. Sex differences in head acceleration during heading while wearing soccer headgear.

    Science.gov (United States)

    Tierney, Ryan T; Higgins, Michael; Caswell, Shane V; Brady, Jessica; McHardy, Krista; Driban, Jeffrey B; Darvish, Kurosh

    2008-01-01

    Researchers have indicated that female soccer players may be at greater risk of concussion compared with their male counterparts. Soccer headgear is marketed for reducing head acceleration and risk of concussion. To determine the effect of sex and soccer headgear on head impact kinematics and dynamic stabilization during soccer heading. Cross-sectional design. Research laboratory. Forty-four college-aged soccer players (29 women, 15 men). Using a head impact model, participants performed 4 soccer headers under 3 headgear conditions (control, Head Blast Soccer Band, and Full90 Select Performance Headguard). Dependent variables assessed before soccer heading were head-neck anthropometrics and isometric neck muscle strength, and those assessed during soccer headers were resultant linear head acceleration, Head Injury Criteria (HIC(36)), and superficial neck muscle electromyography. Statistical analyses included multivariate and univariate analyses of variance with repeated measures, independent-samples t tests, appropriate follow-up analyses of variance and post hoc t tests, and Pearson product moment correlations (alpha = .05). Head acceleration in women was 32% and 44% greater than in men when wearing the Head Blast (21.5 g versus 16.3 g) and Full90 Select (21.8 g versus 15.2 g), respectively (P headgear. Our results are important clinically because they indicate that soccer headgear may not be an appropriate head injury prevention tool for all athletes.

  15. HIV manifestations in the head and neck

    African Journals Online (AJOL)

    Werner Hoek, MB ChB, MMed (ORL)/FCORL (SA). Acting Head of Unit and Specialist, Division of Otolaryngology Head and Neck Surgery, Kimberley Hospital, Northern Cape, and Associate. Lecturer, University of the Free State, Bloemfontein. Dr Hoek's current interest lies in attempting to eradicate the long waiting lists in ...

  16. Head impact in a snowboarding accident.

    Science.gov (United States)

    Bailly, N; Llari, M; Donnadieu, T; Masson, C; Arnoux, P J

    2017-09-01

    To effectively prevent sport traumatic brain injury (TBI), means of protection need to be designed and tested in relation to the reality of head impact. This study quantifies head impacts during a typical snowboarding accident to evaluate helmet standards. A snowboarder numerical model was proposed, validated against experimental data, and used to quantify the influence of accident conditions (speed, snow stiffness, morphology, and position) on head impacts (locations, velocities, and accelerations) and injury risk during snowboarding backward falls. Three hundred twenty-four scenarios were simulated: 70% presented a high risk of mild TBI (head peak acceleration >80 g) and 15% presented a high risk of severe TBI (head injury criterion >1000). Snow stiffness, speed, and snowboarder morphology were the main factors influencing head impact metrics. Mean normal head impact speed (28 ± 6 km/h) was higher than equivalent impact speed used in American standard helmet test (ASTM F2040), and mean tangential impact speed, not included in standard tests, was 13.8 (±7 km/h). In 97% of simulated impacts, the peak head acceleration was below 300 g, which is the pass/fail criteria used in standard tests. Results suggest that initial speed, impacted surface, and pass/fail criteria used in helmet standard performance tests do not fully reflect magnitude and variability of snowboarding backward-fall impacts. © 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  17. Putting two heads together to unwind DNA.

    Science.gov (United States)

    Takara, Thomas J; Bell, Stephen P

    2009-11-13

    The loading of replicative helicases onto DNA is tightly regulated in all organisms, yet the molecular mechanisms for this event remain poorly defined. Remus et al. (2009) provide important insights into helicase loading in eukaryotes, showing that the Mcm2-7 replicative helicase encircles double-stranded DNA as head-to-head double hexamers.

  18. Systematic biases in human heading estimation.

    Directory of Open Access Journals (Sweden)

    Luigi F Cuturi

    Full Text Available Heading estimation is vital to everyday navigation and locomotion. Despite extensive behavioral and physiological research on both visual and vestibular heading estimation over more than two decades, the accuracy of heading estimation has not yet been systematically evaluated. Therefore human visual and vestibular heading estimation was assessed in the horizontal plane using a motion platform and stereo visual display. Heading angle was overestimated during forward movements and underestimated during backward movements in response to both visual and vestibular stimuli, indicating an overall multimodal bias toward lateral directions. Lateral biases are consistent with the overrepresentation of lateral preferred directions observed in neural populations that carry visual and vestibular heading information, including MSTd and otolith afferent populations. Due to this overrepresentation, population vector decoding yields patterns of bias remarkably similar to those observed behaviorally. Lateral biases are inconsistent with standard bayesian accounts which predict that estimates should be biased toward the most common straight forward heading direction. Nevertheless, lateral biases may be functionally relevant. They effectively constitute a perceptual scale expansion around straight ahead which could allow for more precise estimation and provide a high gain feedback signal to facilitate maintenance of straight-forward heading during everyday navigation and locomotion.

  19. Head injury: Calabar Teaching Hospital experience | Ikpeme ...

    African Journals Online (AJOL)

    The pattern and distribution of head injuries shows that a typical head injured patient in our locality is a male, aged between 21 and 30 years involved in a motorcycle related accident. Accidents frequently occured between 7 and 9pm and though 75% of patients arrived in hospital within 6 hours of injury, 17% of all cases ...

  20. "Starfish" Heater Head For Stirling Engine

    Science.gov (United States)

    Vitale, N.

    1993-01-01

    Proposed "starfish" heater head for Stirling engine enables safe use of liquid sodium as heat-transfer fluid. Sodium makes direct contact with heater head but does not come in contact with any structural welds. Design concept minimizes number of, and simplifies nonstructural thermal welds and facilitates inspection of such welds.

  1. Evaluation of head and neck postures

    NARCIS (Netherlands)

    Delleman, N.J.

    2000-01-01

    This paper describes the literature and two experiments on the evaluation of head and neck postures. It is concluded that health and safety professiona1s and ergonomists during posture evaluation should consider neck flexion/extension (head vs. trunk), besides the traditionally used inclination of

  2. The Role of the Primary School Head.

    Science.gov (United States)

    Davies, Lester

    1987-01-01

    This study uses Henry Mintzberg's structural observation method to examine British primary school head teachers' work patterns and determine the nature of their role. Head teachers' days were characterized by brevity, variety, and fragmentation similar to those discussed in findings of other empirical managerial studies. Leadership roles stressed…

  3. Ultrasound examination of the head and neck

    NARCIS (Netherlands)

    R.J. Baatenburg de Jong (Robert Jan); R.J. Rongen (Robert Jan)

    1990-01-01

    textabstractStructure of this thesis Part I deals with basic bio-physics and bio-effects of clinical ultrasound of the head and neck. Furthermore, the ultrasound anatomy of the head and neck is described and illustrated. In addition, the technique of ultrasound guided fine needle aspiration

  4. 76 FR 14841 - Head Start Program

    Science.gov (United States)

    2011-03-18

    ... eligibility information. Programs should be especially sensitive to any potential domestic violence issues... HUMAN SERVICES Administration for Children and Families 45 CFR Part 1305 RIN 0970-AC46 Head Start Program AGENCY: Office of Head Start (OHS), Administration for Children and Families (ACF), Department of...

  5. Heading Tuning in Macaque Area V6.

    Science.gov (United States)

    Fan, Reuben H; Liu, Sheng; DeAngelis, Gregory C; Angelaki, Dora E

    2015-12-16

    Cortical areas, such as the dorsal subdivision of the medial superior temporal area (MSTd) and the ventral intraparietal area (VIP), have been shown to integrate visual and vestibular self-motion signals. Area V6 is interconnected with areas MSTd and VIP, allowing for the possibility that V6 also integrates visual and vestibular self-motion cues. An alternative hypothesis in the literature is that V6 does not use these sensory signals to compute heading but instead discounts self-motion signals to represent object motion. However, the responses of V6 neurons to visual and vestibular self-motion cues have never been studied, thus leaving the functional roles of V6 unclear. We used a virtual reality system to examine the 3D heading tuning of macaque V6 neurons in response to optic flow and inertial motion stimuli. We found that the majority of V6 neurons are selective for heading defined by optic flow. However, unlike areas MSTd and VIP, V6 neurons are almost universally unresponsive to inertial motion in the absence of optic flow. We also explored the spatial reference frames of heading signals in V6 by measuring heading tuning for different eye positions, and we found that the visual heading tuning of most V6 cells was eye-centered. Similar to areas MSTd and VIP, the population of V6 neurons was best able to discriminate small variations in heading around forward and backward headings. Our findings support the idea that V6 is involved primarily in processing visual motion signals and does not appear to play a role in visual-vestibular integration for self-motion perception. To understand how we successfully navigate our world, it is important to understand which parts of the brain process cues used to perceive our direction of self-motion (i.e., heading). Cortical area V6 has been implicated in heading computations based on human neuroimaging data, but direct measurements of heading selectivity in individual V6 neurons have been lacking. We provide the first

  6. Visual perception of axes of head rotation

    Directory of Open Access Journals (Sweden)

    David Mattijs Arnoldussen

    2013-02-01

    Full Text Available Registration of ego-motion is important to accurately navigate through space. Movements of the head and eye relative to space are registered through the vestibular system and optical flow, respectively. Here, we address three questions concerning the visual registration of self-rotation. 1. Eye-in-head movements provide a link between the motion signals received by sensors in the moving eye and sensors in the moving head. How are these signals combined into an ego-rotation percept? We combined optic flow of simulated forward and rotational motion of the eye with different levels of eye-in-head rotation for a stationary head. We dissociated simulated gaze rotation and head rotation by different levels of eye-in-head pursuit.We found that perceived rotation matches simulated head- not gaze-rotation. This rejects a model for perceived self-rotation that relies on the rotation of the gaze line. Rather, eye-in-head signals serve to transform the optic flow’s rotation information, that specifies rotation of the scene relative to the eye, into a rotation relative to the head. This suggests that transformed visual self-rotation signals may combine with vestibular signals.2. Do transformed visual self-rotation signals reflect the arrangement of the semicircular canals (SCC? Previously, we found sub-regions within MST and V6+ that respond to the speed of the simulated head rotation. Here, we re-analyzed those BOLD signals for the presence of a spatial dissociation related to the axes of visually simulated head rotation, such as have been found in sub-cortical regions of various animals. Contrary, we found a rather uniform BOLD response to simulated rotation along the three SCC axes.3. We investigated if subject’s sensitivity to the direction of the head rotation axis shows SCC axes specifcity. We found that sensitivity to head rotation is rather uniformly distributed, suggesting that in human cortex, visuo-vestibular integration is not arranged into

  7. Public knowledge of head and neck cancer.

    LENUS (Irish Health Repository)

    O'Connor, T E

    2010-04-01

    Studies show 60% of patients with newly diagnosed Head & Neck Squamous Cell Cancer in Ireland, present with advanced disease. A poor level of knowledge and awareness among the public of Head & Neck Cancer, is an important consideration in the often delayed presentation for medical attention in many of these cases. Our study surveyed 200 members of the public to assess their knowledge and awareness of Head & Neck Cancer. One hundred and forty (70%) of respondents had never encountered the term "Head & Neck Cancer". One hundred and forty six (73%) failed to identify excessive alcohol consumption as a risk factor. Less than 100 (50%) would have concern about persisting hoarseness or a prolonged oral ulcer. An urgent need exists to raise awareness of Head & Neck Cancer among the public in Ireland.

  8. Introduction of the integrated head package

    Energy Technology Data Exchange (ETDEWEB)

    Kim, T. K.; Jin, C. E.; Kim, I. Y

    1999-12-01

    This paper introduces the basic features of the various types of Reactor Vessel (RV) head area structures used in the nuclear power plant and developed in these days. The previous RV head area structures consist of many components that needed to be disassembled, removed and stored individually during every refueling outage. The Integrated Head Assembly (IHA) developed by KOPEC is considered as a mechanical system that combines the RV head lifting device, the CEDM seismic support device, the missile shield, the CEDM cooling components and the head area cable system into one efficient assembly, which can be handled together as a single assembly. Also, the IHA is designed to accommodate a Multiple Stud Tensioner (MST). It is expected that IHA will contribute to reduction in refueling outage time as well as reduction in radiation exposure to operators. (author)

  9. Head orientation prediction: delta quaternions versus quaternions.

    Science.gov (United States)

    Himberg, Henry; Motai, Yuichi

    2009-12-01

    Display lag in simulation environments with helmet-mounted displays causes a loss of immersion that degrades the value of virtual/augmented reality training simulators. Simulators use predictive tracking to compensate for display lag, preparing display updates based on the anticipated head motion. This paper proposes a new method for predicting head orientation using a delta quaternion (DQ)-based extended Kalman filter (EKF) and compares the performance to a quaternion EKF. The proposed framework operates on the change in quaternion between consecutive data frames (the DQ), which avoids the heavy computational burden of the quaternion motion equation. Head velocity is estimated from the DQ by an EKF and then used to predict future head orientation. We have tested the new framework with captured head motion data and compared it with the computationally expensive quaternion filter. Experimental results indicate that the proposed DQ method provides the accuracy of the quaternion method without the heavy computational burden.

  10. Head positioning for anterior circulation aneurysms microsurgery

    Directory of Open Access Journals (Sweden)

    Feres Chaddad-Neto

    2014-11-01

    Full Text Available Objective To study the ideal patient's head positioning for the anterior circulation aneurysms microsurgery. Method We divided the study in two parts. Firstly, 10 fresh cadaveric heads were positioned and dissected in order to ideally expose the anterior circulation aneurysm sites. Afterwards, 110 patients were submitted to anterior circulation aneurysms microsurgery. During the surgery, the patient's head was positioned accordingly to the aneurysm location and the results from the cadaveric study. The effectiveness of the position was noted. Results We could determine mainly two patterns for head positioning for the anterior circulation aneurysms. Conclusion The best surgical exposure is related to specific head positions. The proper angle of microscopic view may minimize neurovascular injury and brain retraction.

  11. Sword-Like Trauma to the Shoulder with Open Head-Splitting Fracture of the Head

    Directory of Open Access Journals (Sweden)

    Andreas Panagopoulos

    2016-01-01

    Full Text Available Head-splitting fractures occur as a result of violent compression of the head against the glenoid; the head splits and the tuberosities may remain attached to the fragments or split and separate. Isolated humeral head-splitting fractures are rare injuries. Favorable results with osteosynthesis can be difficult to achieve because of the very proximal location of the head fracture and associated poor vascularity. We present a case of a 67-year-old man who sustained a severe, sword-like trauma to his left shoulder after a road traffic accident with associated isolated open Gustilo-Anderson IIIA humeral head-splitting fracture. Bony union was achieved with minimal internal fixation but the clinical outcome deteriorated due to accompanying axillary nerve apraxia. To our knowledge, this type of sword-like injury with associated humeral head-split fracture has not previously been reported.

  12. Sword-Like Trauma to the Shoulder with Open Head-Splitting Fracture of the Head.

    Science.gov (United States)

    Panagopoulos, Andreas; Pantazis, Konstantinos; Iliopoulos, Ilias; Seferlis, Ioannis; Kokkalis, Zinon

    2016-01-01

    Head-splitting fractures occur as a result of violent compression of the head against the glenoid; the head splits and the tuberosities may remain attached to the fragments or split and separate. Isolated humeral head-splitting fractures are rare injuries. Favorable results with osteosynthesis can be difficult to achieve because of the very proximal location of the head fracture and associated poor vascularity. We present a case of a 67-year-old man who sustained a severe, sword-like trauma to his left shoulder after a road traffic accident with associated isolated open Gustilo-Anderson IIIA humeral head-splitting fracture. Bony union was achieved with minimal internal fixation but the clinical outcome deteriorated due to accompanying axillary nerve apraxia. To our knowledge, this type of sword-like injury with associated humeral head-split fracture has not previously been reported.

  13. Head circumference in Iranian infants

    Directory of Open Access Journals (Sweden)

    Mohammad Esmaeili

    2015-03-01

    Full Text Available Introduction: Head circumference (HC measurement is one of the important parameter for diagnosis of neurological, developmental disorders and dysmorphic syndromes. Recognition of different disorders requires an understanding of normal variation for HC size, in particular, in infancy period with most rapid growth of the brain. Because of international and interracial standard chart differences about anthropometric indices, some differences from local to local, generation to generation and changes in ethnic mix of population and socioeconomic factors, periodic revolution of HC size is suggested. The aims of our study were presenting local HC standard for an Iranian infant population and comparison with the American national center of health statistics (NCHS charts accepted by WHO. Methods: 1003 subjects aged from birth to 24 months apparently healthy normal children enrolled randomly in this cross sectional study. HC size were measured and recorded. Tables and graphs were depicted by Excel Microsoft Office 2007. We use two tailed t-student test for statistical analysis. Results: The mean of HC size in boys was larger than girls. The curves were followed a similar pattern to NCHS based on a visual comparison. Overall our subjects in both sexes at birth time had smaller HC size than NCHS. In other ages our children had larger HC size than those of NCHS. Conclusion: Because of international and interracial difference of HC size. We recommend in each area of the world, local anthropometric indices are constructed and used clinically. In addition more extensive and longitudinally design comprehensive studies is suggested.

  14. Prognosis of severe head injuries.

    Science.gov (United States)

    Levati, A; Farina, M L; Vecchi, G; Rossanda, M; Marrubini, M B

    1982-12-01

    The authors have analyzed retrospectively a series of 288 consecutive patients with severe head injury observed between January, 1977, and May, 1980. Seventy-three patients were excluded as not being compatible with those of the International Data Bank. The remaining 215 patients complied with the definition of coma given by Jennett. All patients, after appropriate cardiopulmonary resuscitation, diagnostic measures, and, when required, surgical treatment, were managed in the Neurosurgical Intensive Care Unit with endotracheal intubation, controlled hyperventilation, mild dehydration, dexamethasone in standard doses, and sedation. The mortality rate was 39.5%. Of the survivors, 59.2% made a good recovery, 18.4% remained moderately disabled, 6.1% were severely disabled, and 1.5% were in a persistent vegetative state. The most reliable predictive criteria were: absence of brain-stem reflexes, neurological status, abnormal motor patterns, arterial hypotension, and presence of mass lesions. It is concluded that no sign has an absolute prognostic value when considered independently of its time course.

  15. Indirect Measurement of Head Orientation During Gy Acceleration

    National Research Council Canada - National Science Library

    Brungart, Douglas

    1995-01-01

    .... A retroactive study of data from +Gy impacts of instrumented human volunteers and manikins attempted to determine head position during peak head acceleration from the direction of the head acceleration vector...

  16. Head flexion angle while using a smartphone.

    Science.gov (United States)

    Lee, Sojeong; Kang, Hwayeong; Shin, Gwanseob

    2015-01-01

    Repetitive or prolonged head flexion posture while using a smartphone is known as one of risk factors for pain symptoms in the neck. To quantitatively assess the amount and range of head flexion of smartphone users, head forward flexion angle was measured from 18 participants when they were conducing three common smartphone tasks (text messaging, web browsing, video watching) while sitting and standing in a laboratory setting. It was found that participants maintained head flexion of 33-45° (50th percentile angle) from vertical when using the smartphone. The head flexion angle was significantly larger (p smartphone, could be a main contributing factor to the occurrence of neck pain of heavy smartphone users. Practitioner Summary: In this laboratory study, the severity of head flexion of smartphone users was quantitatively evaluated when conducting text messaging, web browsing and video watching while sitting and standing. Study results indicate that text messaging while sitting caused the largest head flexion than that of other task conditions.

  17. Projection/Reflection Heads-up Display

    Data.gov (United States)

    National Aeronautics and Space Administration — To address the NASA need for an EVA information display device, Physical Optics Corporation (POC) proposes to develop a new Projection/Reflection Heads-up Display...

  18. [Mild head injuries in the elderly].

    Science.gov (United States)

    Thaler, Heinrich W; Jung-Schmidsfeld, Jochen; Pienaar, Simon

    2017-07-01

    In the elderly, particularly those over 80 years old, head injuries often occur as a result of falls. The majority suffer from mild head injury. After clarification of the initial symptoms in these patients, the main aim is to recognize or exclude intracranial injuries (bleeding). Demonstration of intracranial bleeding is possible with cranial computed tomography (CCT), which in contrast to magnetic resonance imaging (MRI) can be quickly carried out in most cases; however, most patients with mild head injury show no intracranial bleeding. The performance of CCT and the often necessary hospital admission place a severe physical and psychological burden on the elderly. The plasma parameter S100B, combined with the clinical findings, is a valuable instrument for decision making in the management of elderly patients with mild head injury.

  19. "Head õhtut ja õnn kaasa" / Triin Thalheim

    Index Scriptorium Estoniae

    Thalheim, Triin, 1982-

    2006-01-01

    George Clooney mängufilm "Head õhtut ja õnn kaasa" ("Good Night, and Good Luck") teleajakirjanik Edward R. Murrow võitlusest senaator Joseph McCarthy vastu. Lisatud "Filmi ajaloolised võtmetegelased"

  20. Engineering science and mechanics department head named

    OpenAIRE

    Nystrom, Lynn A.

    2004-01-01

    Ishwar K. Puri, professor of mechanical engineering and executive associate dean of engineering at the University of Illinois at Chicago, will become the head of Virginia Tech•À_ó»s Department of Engineering Science and Mechanics Aug. 1.

  1. Drugs Approved for Head and Neck Cancer

    Science.gov (United States)

    This page lists cancer drugs approved by the Food and Drug Administration (FDA) for head and neck cancer. The list includes generic names and brand names. The drug names link to NCI’s Cancer Drug Information summaries.

  2. 33 CFR 142.30 - Head protection.

    Science.gov (United States)

    2010-07-01

    ... protection. (a) Personnel in areas where there is a hazard of falling objects or of contact with electrical conductors shall wear a head protector meeting the specifications of ANSI Z89.1, for the hazard involved. (b...

  3. 29 CFR 1915.155 - Head protection.

    Science.gov (United States)

    2010-07-01

    ... designed to reduce electrical shock hazards where there is potential for electric shock or burns due to contact with exposed electrical conductors which could contact the head. (b) Criteria for protective...

  4. 29 CFR 1910.135 - Head protection.

    Science.gov (United States)

    2010-07-01

    ... shall ensure that a protective helmet designed to reduce electrical shock hazard is worn by each such affected employee when near exposed electrical conductors which could contact the head. (b) Criteria for...

  5. TMI-2 reactor vessel head removal

    Energy Technology Data Exchange (ETDEWEB)

    Bengel, P.R.; Smith, M.D.; Estabrook, G.A.

    1985-09-01

    This report describes the safe removal and storage of the Three Mile Island Unit 2 (TMI-2) reactor vessel head. The head was removed in July 1984 to permit the removal of the plenum and the reactor core, which were damaged during the 1979 accident. From July 1982, plans and preparations were made using a standard head removal procedure modified by the necessary precautions and changes to account for conditions caused by the accident. After data acquisition, equipment and structure modifications, and training, the head was safely removed and stored; and the internals indexing fixture and a work platform were installed on top of the vessel. Dose rates during and after the operation were lower than expected; lessons were learned from the operation which will be applied to the continuing fuel removal operations activities.

  6. TMI-2 reactor vessel head removal

    Energy Technology Data Exchange (ETDEWEB)

    Bengel, P.R.; Smith, M.D.; Estabrook, G.A.

    1984-12-01

    This report describes the safe removal and storage of the Three Mile Island Unit 2 reactor vessel head. The head was removed in July 1984 to permit the removal of the plenum and the reactor core, which were damaged during the 1979 accident. From July 1982, plans and preparations were made using a standard head removal procedure modified by the necessary precautions and changes to account for conditions caused by the accident. After data acquisition, equipment and structure modifications, and training the head was safely removed and stored and the internals indexing fixture and a work platform were installed on top of the vessel. Dose rates during and after the operation were lower than expected; lessons were learned from the operation which will be applied to the continuing fuel removal operations activities.

  7. Head of Department of Mechanical Engineering appointed

    OpenAIRE

    Nystrom, Lynn A.

    2004-01-01

    Kenneth S. Ball, professor of mechanical engineering at the University of Texas at Austin, will become the head of the Department of Mechanical Engineering in Virginia Tech's College of Engineering Aug. 1.

  8. Head development. Craniofacial genetics makes headway.

    Science.gov (United States)

    Richman, J M

    1995-04-01

    Studies of neural crest migration in animal models, and of human syndromes in which craniofacial development is abnormal, are helping us to understand both prenatal and postnatal development of the head.

  9. Achieving Consensus Through Professionalized Head Nods

    DEFF Research Database (Denmark)

    Oshima, Sae

    2014-01-01

    of nodding in a particular professional-client setting, namely, hair salon interactions. My interest specifically lies in the frequent occurrence of synchronized head nods during the “service-assessment sequence,” where both service provider and customer inspect and determine whether the completed work......While the interactional functions of head nodding in everyday Japanese conversation have been frequently studied, a discourse on head nodding as a professional communicative practice has yet to be explored. With the method of multimodal conversation analysis, the current study examines the role...... is adequate. I pursue mechanisms of synchronized head nods by revealing exactly how participants collaborate in producing a nod, and how their verbal actions may at times be designed accordingly. In doing so, the study provides insight into what consensus may look like at service encounters in Japan...

  10. Schwannomas of the head and neck

    Directory of Open Access Journals (Sweden)

    Anastasios Kanatas

    2011-12-01

    Full Text Available Schwannomas are benign encapsulated nerve sheath tumors composed of Schwann cells. Malignant change in head and neck schwannomas is rare, with the incidence varying between 8 and 13.9%. In this review, we discuss the presentation and the management of head and neck schwannomas. The issues and difficulties based on our own experience as well as the experience of published reports from the literature are presented.

  11. Civilian firearm injuries in head and neck

    OpenAIRE

    Sonkhya, Nishi; Singhal, Pawan; Srivastava, Subodh P.

    2005-01-01

    Firearm injuries to the head and neck contribute to substantial medical, medicolegal, economic as well as social problems. Internal wounds in the head and neck by firearms are usually complicated and are diagnostically and therapeutically challenging cases. Based on four cases of non-fatal firearm injuries, we discuss problems related to firearm wounds, their irregular path, final lodgment of the bullet and their diagnostic and therapeutic consequences. In the present study it was observed th...

  12. Head impact exposure in collegiate football players.

    Science.gov (United States)

    Crisco, Joseph J; Wilcox, Bethany J; Beckwith, Jonathan G; Chu, Jeffrey J; Duhaime, Ann-Christine; Rowson, Steven; Duma, Stefan M; Maerlender, Arthur C; McAllister, Thomas W; Greenwald, Richard M

    2011-10-13

    In American football, impacts to the helmet and the resulting head accelerations are the primary cause of concussion injury and potentially chronic brain injury. The purpose of this study was to quantify exposures to impacts to the head (frequency, location and magnitude) for individual collegiate football players and to investigate differences in head impact exposure by player position. A total of 314 players were enrolled at three institutions and 286,636 head impacts were recorded over three seasons. The 95th percentile peak linear and rotational acceleration and HITsp (a composite severity measure) were 62.7g, 4378rad/s(2) and 32.6, respectively. These exposure measures as well as the frequency of impacts varied significantly by player position and by helmet impact location. Running backs (RB) and quarter backs (QB) received the greatest magnitude head impacts, while defensive line (DL), offensive line (OL) and line backers (LB) received the most frequent head impacts (more than twice as many than any other position). Impacts to the top of the helmet had the lowest peak rotational acceleration (2387rad/s(2)), but the greatest peak linear acceleration (72.4g), and were the least frequent of all locations (13.7%) among all positions. OL and QB had the highest (49.2%) and the lowest (23.7%) frequency, respectively, of front impacts. QB received the greatest magnitude (70.8g and 5428rad/s(2)) and the most frequent (44% and 38.9%) impacts to the back of the helmet. This study quantified head impact exposure in collegiate football, providing data that is critical to advancing the understanding of the biomechanics of concussive injuries and sub-concussive head impacts. Copyright © 2011 Elsevier Ltd. All rights reserved.

  13. Head Impact Biomechanics in Women's College Soccer.

    Science.gov (United States)

    Lynall, Robert C; Clark, Michael D; Grand, Erin E; Stucker, Jaclyn C; Littleton, Ashley C; Aguilar, Alain J; Petschauer, Meredith A; Teel, Elizabeth F; Mihalik, Jason P

    2016-09-01

    There are limited nonlaboratory soccer head impact biomechanics data. This is surprising given soccer's global popularity. Epidemiological data suggest that female college soccer players are at a greater concussion injury risk than their male counterparts. Therefore, the purposes of our study were to quantify head impact frequency and magnitude during women's soccer practices and games in the National Collegiate Athletic Association and to characterize these data across event type, playing position, year on the team, and segment of game (first and second halves). Head impact biomechanics were collected from female college soccer players (n = 22; mean ± SD age = 19.1 ± 0.1 yr, height = 168.0 ± 3.5 cm, mass = 63.7 ± 6.0 kg). We employed a helmetless head impact measurement device (X2 Biosystems xPatch) before each competition and practice across a single season. Peak linear and rotational accelerations were categorized based on impact magnitude and subsequently analyzed using appropriate nonparametric analyses. Overall, women's college soccer players experience approximately seven impacts per 90 min of game play. The overwhelming majority (~90%) of all head impacts were categorized into our mildest linear acceleration impact classification (10g-20g). Interestingly, a higher percentage of practice impacts in the 20g-40g range compared with games (11% vs 7%) was observed. Head impact biomechanics studies have provided valuable insights into understanding collision sports and for informing evidence-based rule and policy changes. These have included changing the football kickoff, ice hockey body checking ages, and head-to-head hits in both sports. Given soccer's global popularity, and the growing public concern for the potential long-term neurological implications of collision and contact sports, studying soccer has the potential to impact many athletes and the sports medicine professionals caring for them.

  14. Imaging of accidental paediatric head trauma

    Energy Technology Data Exchange (ETDEWEB)

    Tang, Phua Hwee [KK Women' s and Children' s Hospital, Department of Diagnostic Imaging, Singapore (Singapore); Lim, Choie Cheio Tchoyoson [National Neuroscience Institute, Department of Neuroradiology, Singapore (Singapore)

    2009-05-15

    Head trauma is the most common form of injury sustained in serious childhood trauma and remains one of the top three causes of death despite improved road planning and safety laws. CT remains the first-line investigation for paediatric head trauma, although MRI may be more sensitive at picking up the full extent of injuries and may be useful for prognosis. Follow-up imaging should be tailored to answer the specific clinical question and to look for possible complications. (orig.)

  15. Learning toward practical head pose estimation

    Science.gov (United States)

    Sang, Gaoli; He, Feixiang; Zhu, Rong; Xuan, Shibin

    2017-08-01

    Head pose is useful information for many face-related tasks, such as face recognition, behavior analysis, human-computer interfaces, etc. Existing head pose estimation methods usually assume that the face images have been well aligned or that sufficient and precise training data are available. In practical applications, however, these assumptions are very likely to be invalid. This paper first investigates the impact of the failure of these assumptions, i.e., misalignment of face images, uncertainty and undersampling of training data, on head pose estimation accuracy of state-of-the-art methods. A learning-based approach is then designed to enhance the robustness of head pose estimation to these factors. To cope with misalignment, instead of using hand-crafted features, it seeks suitable features by learning from a set of training data with a deep convolutional neural network (DCNN), such that the training data can be best classified into the correct head pose categories. To handle uncertainty and undersampling, it employs multivariate labeling distributions (MLDs) with dense sampling intervals to represent the head pose attributes of face images. The correlation between the features and the dense MLD representations of face images is approximated by a maximum entropy model, whose parameters are optimized on the given training data. To estimate the head pose of a face image, its MLD representation is first computed according to the model based on the features extracted from the image by the trained DCNN, and its head pose is then assumed to be the one corresponding to the peak in its MLD. Evaluation experiments on the Pointing'04, FacePix, Multi-PIE, and CASIA-PEAL databases prove the effectiveness and efficiency of the proposed method.

  16. Overhead shoulder press – In-front of the head or behind the head?

    Directory of Open Access Journals (Sweden)

    Mark R. McKean

    2015-09-01

    Conclusion: Shoulder ROM was within passive ROM for all measures except external rotation for males with the behind the head technique. To avoid possible injury passive ROM should be increased prior to behind the head protocol. Females showed greater spine movements, suggesting trunk strengthening may assist overhead pressing techniques. For participants with normal trunk stability and ideal shoulder ROM, overhead pressing is a safe exercise (for the shoulder and spine when performed either in-front of or behind the head.

  17. Covariance analysis for evaluating head trackers

    Science.gov (United States)

    Kang, Donghoon

    2017-10-01

    Existing methods for evaluating the performance of head trackers usually rely on publicly available face databases, which contain facial images and the ground truths of their corresponding head orientations. However, most of the existing publicly available face databases are constructed by assuming that a frontal head orientation can be determined by compelling the person under examination to look straight ahead at the camera on the first video frame. Since nobody can accurately direct one's head toward the camera, this assumption may be unrealistic. Rather than obtaining estimation errors, we present a method for computing the covariance of estimation error rotations to evaluate the reliability of head trackers. As an uncertainty measure of estimators, the Schatten 2-norm of a square root of error covariance (or the algebraic average of relative error angles) can be used. The merit of the proposed method is that it does not disturb the person under examination by asking him to direct his head toward certain directions. Experimental results using real data validate the usefulness of our method.

  18. Fever in pregnancy and offspring head circumference.

    Science.gov (United States)

    Dreier, Julie Werenberg; Strandberg-Larsen, Katrine; Uldall, Peter Vilhelm; Nybo Andersen, Anne-Marie

    2017-12-06

    To examine whether maternal fever during pregnancy is associated with reduced head circumference and risk of microcephaly at birth. A prospective study of 86,980 live-born singletons within the Danish National Birth Cohort was carried out. Self-reported maternal fever exposure was ascertained in two interviews during pregnancy and information on head circumference at birth was extracted from the Danish Medical Birth Registry. Fever in pregnancy was reported by 27% of the mothers, and we identified 3370 cases of microcephaly (head circumference less than or equal to third percentile for sex and gestational age) and 1140 cases of severe microcephaly (head circumference less than or equal to first percentile for sex and gestational age). In this study, maternal fever exposure was not associated with reduced head circumference (adjusted β = 0.03, 95% confidence intervals [CI]: 0.01-0.05), increased risk of microcephaly (odds ratio: 0.95, 95% CI: 0.88-1.03) nor severe microcephaly (odds ratio: 1.01, 95% CI: 0.88-1.15) in the offspring. These findings were consistent for increasing numbers of fever episodes, for increasing fever severity, and for exposure in both early pregnancy and midpregnancy. In this most comprehensive study to date, we found no indication that maternal fever in pregnancy is associated with small head size in the offspring. Copyright © 2017 Elsevier Inc. All rights reserved.

  19. Head injuries of Roman gladiators.

    Science.gov (United States)

    Kanz, Fabian; Grossschmidt, Karl

    2006-07-13

    Gladiator remains from a recently unearthed cemetery in ancient Ephesus (Turkey) offer a unique opportunity for proving common theories involving the weaponry and techniques of gladiator fighting based on the evidence supplied by cranial bones. This mass grave is the first of its kind to undergo a thorough osteological and forensic examination. A minimum number of individuals (MNI) analyses revealed that at least 68 individuals. All individuals found turned out to have been males aged between 20 and 30 years, except for one female associated with a female slave gravestone, and one male aged 45-55 years, had been buried in this area of the cemetery. The male mean body height was 168 cm (S.D.=5 cm), which lies inside the normal range of height for Roman populations at those times. Eleven (16% of MNI) individuals exhibit a total of 16 well-healed antemortal cranial traumata. Five of the 11 individuals showed multiple trauma. Ten (15% of MNI) individuals exhibited a total of 10 perimortal cranial traumata. This is a surprisingly high frequency of deadly head injuries, taking into account that most of the gladiator types wore helmets. A possible explanation could be the frequently reported deathblow technique used by the hammer-carrying death god "Dis Pater". The gladiator weaponry is well known through historical sources. At least one injury per known type of offensive weapon could be identified, as well as evidence for the most popular, the gladiator trident, which was found to be represented by one perimortem and two antemortem injuries. Overall the reportedly very strict nature of combat rules for gladiator fights could be confirmed by the absence of multiple perimortal traumatized individuals, showing a lack of the excessive violence commonly observed on medieval battle ground victims. This graveyard gives the opportunity to confirm historical aspects and to check the reliability of forensic methods for identification of antemortem, perimortem, or postmortem bone

  20. Head phenotypes based on cephalic index among Ukwuani people ...

    African Journals Online (AJOL)

    Background: Head shape based on cephalic index has been used by anthropologists as a measure of classifying humans. Cephalic index is derived from head length and head width. Objective: To find out the dominant head phenotypes based on cephalic index in relation to age. Design: A cross-sectional study.

  1. Head, neck, and body coupling in reconstructions of helmeted head impacts

    NARCIS (Netherlands)

    Lange, R. de; Cappon, H.J.; Beusenberg, C.M.; Shewchenko, N.; Newman, J.A.

    2001-01-01

    A mathematical modeling study is conducted to investigate neck coupling in helmeted head impacts. The main objective of the study is to provide direction for the experimental reconstruction of American football player impacts. Head responses are compared in MADYMO simulations of various impact

  2. Plaque removal with triple-headed vs single-headed manual toothbrushes-a systematic review

    NARCIS (Netherlands)

    Kalf-Scholte, S. M.; van der Weijden, G. A.; Bakker, E. W. P.; Slot, D. E.

    2017-01-01

    The aim of this systematic review was to establish the effectiveness of brushing with a triple-headed manual toothbrush compared to a single-headed manual toothbrush on plaque removal. The MEDLINE-PubMed and Cochrane-CENTRAL databases were searched. The inclusion criteria were clinical trials

  3. Microbial contamination of power toothbrushes: a comparison of solid-head versus hollow-head designs.

    Science.gov (United States)

    Morris, Donna W; Goldschmidt, Millicent; Keene, Harris; Cron, Stanley G

    2014-08-01

    Microbial contamination of manual toothbrushes relative to their design has been documented for decades, citing concern for cross contamination and self-infection with microorganisms. A pilot study of different power toothbrushes was conducted, to compare a solid-head brush to 2 hollow-head brushes for residual contamination with commonly occurring oral microorganisms. Participants who met inclusion criteria were enrolled and brushed twice daily for 3 weeks with 1 of 3 randomly assigned power toothbrushes. Brush heads were vortexed and cultured using 5 appropriate media for oral microorganisms: anaerobes and facultative microorganisms, yeast and mold, oral streptococci and oral enterococci anaerobes, Porphyromonas gingivalis, and Fusobacterium species. Analysis of covariance was used to compare the brush groups for transformed microbial counts after adjusting for any demographic variables that may have confounded the results. The solid-head power toothbrush was found to have significantly less microbial contamination than either of the 2 hollow-head power toothbrushes for all the bacteria tested and less than 1 of the hollow-head brushes for yeast and mold. The solid-head power toothbrush studied had significantly less residual microbial contamination than the 2 hollow-head power toothbrushes after 3 weeks of twice daily brushing with non-antimicrobial toothpaste. Copyright © 2014 The American Dental Hygienists’ Association.

  4. The Spec-head vs head-Spec asymmetry: Toward a theory of post ...

    African Journals Online (AJOL)

    Mark

    The Spec-head vs head-Spec asymmetry: Toward a theory of post- syntactic linearization and an account of the ... of Relational Theory and empirically investigates topicalization constructions in English which have somewhat paradoxical ...... New York/London: The Macmillan Company. Rivero, M.-L. 1978. Topicalization ...

  5. The Relationship Between the Head and the Deputy Head in Primary Schools.

    Science.gov (United States)

    Hughes, Mike; James, Chris

    1999-01-01

    Explores the primary deputy head's role, focusing on the deputy/head interrelationship, based on interviews with administrators of 10 (British) primary schools. Identifies factors influencing this interrelationship, highlighting partner similarities and the use of complementarity, compensation, tolerance, acceptance, and accommodation to handle…

  6. Head-to-head linked double calix[4]arenes: convenient synthesis and complexation properties

    NARCIS (Netherlands)

    Struck, O.; Struck, Oliver; Chrisstoffels, L.A.J.; Lugtenberg, R.J.W.; Verboom, Willem; van Hummel, G.J.; Harkema, Sybolt; Reinhoudt, David

    1997-01-01

    Combination of calix[4]arenes functionalized at the upper rim at the 5- and 17-positions with amino and formyl groups, respectively, gives a new series of "head-to-head" linked double calix[4]arenes in nearly quantitative yield. The X-ray structure of a modified double calix[4]arene is reported. The

  7. Late radial head dislocation with radial head fracture and ulnar plastic deformation

    NARCIS (Netherlands)

    Heinrich, Stephen D.; Butler, R. Allen

    Type 11 Monteggia lesion equivalents produced by plastic deformation of the ulna are rare. Radial head fractures in skeletally immature patients are also uncommon. We report a late presentation of a Type 11 Monteggia equivalent injury with a fracture of the radial head and neck and plastic

  8. Head Rotation Detection in Marmoset Monkeys

    Science.gov (United States)

    Simhadri, Sravanthi

    Head movement is known to have the benefit of improving the accuracy of sound localization for humans and animals. Marmoset is a small bodied New World monkey species and it has become an emerging model for studying the auditory functions. This thesis aims to detect the horizontal and vertical rotation of head movement in marmoset monkeys. Experiments were conducted in a sound-attenuated acoustic chamber. Head movement of marmoset monkey was studied under various auditory and visual stimulation conditions. With increasing complexity, these conditions are (1) idle, (2) sound-alone, (3) sound and visual signals, and (4) alert signal by opening and closing of the chamber door. All of these conditions were tested with either house light on or off. Infra-red camera with a frame rate of 90 Hz was used to capture of the head movement of monkeys. To assist the signal detection, two circular markers were attached to the top of monkey head. The data analysis used an image-based marker detection scheme. Images were processed using the Computation Vision Toolbox in Matlab. The markers and their positions were detected using blob detection techniques. Based on the frame-by-frame information of marker positions, the angular position, velocity and acceleration were extracted in horizontal and vertical planes. Adaptive Otsu Thresholding, Kalman filtering and bound setting for marker properties were used to overcome a number of challenges encountered during this analysis, such as finding image segmentation threshold, continuously tracking markers during large head movement, and false alarm detection. The results show that the blob detection method together with Kalman filtering yielded better performances than other image based techniques like optical flow and SURF features .The median of the maximal head turn in the horizontal plane was in the range of 20 to 70 degrees and the median of the maximal velocity in horizontal plane was in the range of a few hundreds of degrees per

  9. Automatic classification of human sperm head morphology.

    Science.gov (United States)

    Chang, Violeta; Heutte, Laurent; Petitjean, Caroline; Härtel, Steffen; Hitschfeld, Nancy

    2017-05-01

    Infertility is a problem that affects up to 15% of couples worldwide with emotional and physiological implications and semen analysis is the first step in the evaluation of an infertile couple. Indeed the morphology of human sperm cells is considered to be a clinical tool dedicated to the fertility prognosis and serves, mainly, for making decisions regarding the options of assisted reproduction technologies. Therefore, a complete analysis of not only normal sperm but also abnormal sperm turns out to be critical in this context. This paper sets out to develop, implement and calibrate a novel methodology to characterize and classify sperm heads towards morphological sperm analysis. Our work is aimed at focusing on a depth analysis of abnormal sperm heads for fertility diagnosis, prognosis, reproductive toxicology, basic research or public health studies. We introduce a morphological characterization for human sperm heads based on shape measures. We also present a pipeline for sperm head classification, according to the last Laboratory Manual for the Examination and Processing of Human Semen of the World Health Organization (WHO). In this sense, we propose a two-stage classification scheme that permits to classify sperm heads among five different classes (one class for normal sperm heads and four classes for abnormal sperm heads) combining an ensemble strategy for feature selection and a cascade approach with several support vector machines dedicated to the verification of each class. We use Fisher's exact test to demonstrate that there is no statistically significant differences between our results and those achieved by domain experts. Experimental evaluation shows that our two-stage classification scheme outperforms some state-of-the-art monolithic classifiers, exhibiting 58% of average accuracy. More interestingly, on the subset of data for which there is a total agreement between experts for the label of the samples, our system is able to provide 73% of average

  10. Integrative Medicine in Head and Neck Cancer.

    Science.gov (United States)

    Matovina, Chloe; Birkeland, Andrew C; Zick, Suzanna; Shuman, Andrew G

    2017-02-01

    Objective Complementary and alternative medicine, or integrative medicine, has become increasingly popular among patients with head and neck cancer. Despite its increasing prevalence, many patients feel uncomfortable discussing such therapies with their physicians, and many physicians are unaware and underequipped to evaluate or discuss their use with patients. The aim of this article is to use recent data to outline the decision making inherent to integrative medicine utilization among patients with head and neck cancer, to discuss the ethical implications inherent to balancing integrative and conventional approaches to treatment, and to highlight available resources to enhance head and neck cancer providers' understanding of integrative medicine. Data Sources Randomized controlled trials involving integrative medicine or complementary and alternative medicine treatment for cancer patients. Review Methods Trials were drawn from a systematic PubMed database search categorized into cancer prevention, treatment, and symptom management. Conclusions Integrative medicine is gaining popularity for the management of cancer and is most commonly used for symptom management. A number of randomized controlled trials provide data to support integrative therapies, yet physicians who treat head and neck cancer may be faced with ethical dilemmas and practical barriers surrounding incorporation of integrative medicine. Implications for Practice In the management of head and neck cancer, there is an increasing demand for awareness of, dialogue about, and research evaluating integrative medicine therapies. It is important for otolaryngologists to become aware of integrative therapy options, their risks and benefits, and resources for further information to effectively counsel their patients.

  11. Ulnar Head Replacement and Related Biomechanics

    Science.gov (United States)

    Sauerbier, Michael; Arsalan-Werner, Annika; Enderle, Elena; Vetter, Miriam; Vonier, Daniel

    2013-01-01

    A stable distal radioulnar joint (DRUJ) is mandatory for the function and load transmission in the wrist and forearm. Resectional salvage procedures such as the Darrach procedure, Bowers arthroplasty, and Sauvé-Kapandji procedure include the potential risk of radioulnar instability and impingement, which can lead to pain and weakness. Soft tissue stabilizing techniques have only limited success rates in solving these problems. In an attempt to stabilize the distal forearm mechanically following ulnar head resection, various endoprostheses have been developed to replace the ulnar head. The prostheses can be used for secondary treatment of failed ulnar head resection, but they can also achieve good results in the primary treatment of osteoarthritis of the DRUJ. Our experience consists of twenty-five patients (follow-up 30 months) with DRUJ osteoarthritis who were treated with an ulnar head prosthesis, with improvement in pain, range of motion, and grip strength. An ulnar head prosthesis should be considered as a treatment option for a painful DRUJ. PMID:24436786

  12. Car Accident Reconstruction and Head Injury Correlation

    Science.gov (United States)

    Chawla, A.; Grover, V.; Mukherjee, S.; Hassan, A. M.

    2013-04-01

    Estimation of brain damage remains an elusive issue and controlled tests leading to brain damage cannot be carried out on volunteers. This study reconstructs real-world car accidents to estimate the kinematics of the head impact. This data is to be used to estimate the head injury measures through computer simulations and then correlate reported skull as well as brain damage to impact measures; whence validating the head FE model (Willinger, IJCrash 8:605-617, 2003). In this study, two crash cases were reconstructed. Injury correlation was successful in one of these cases in that the injuries to the brain of one of the car drivers could be correlated in terms of type, location and severity when compared with the tolerance limits of relevant injury parameters (Willinger, IJCrash 8:605-617, 2003).

  13. Perfusion CT of head and neck cancer

    Energy Technology Data Exchange (ETDEWEB)

    Razek, Ahmed Abdel Khalek Abdel, E-mail: arazek@mans.edu.eg; Tawfik, Ahmed Mohamed, E-mail: ahm_m_tawfik@hotmail.com; Elsorogy, Lamiaa Galal Ali, E-mail: lamia2elsorogy@hotmail.com; Soliman, Nermin Yehia, E-mail: nermin_eid@hotmail.com

    2014-03-15

    We aim to review the technique and clinical applications of perfusion CT (PCT) of head and neck cancer. The clinical value of PCT in the head and neck includes detection of head and neck squamous cell carcinoma (HNSCC) as it allows differentiation of HNSCC from normal muscles, demarcation of tumor boundaries and tumor local extension, evaluation of metastatic cervical lymph nodes as well as determination of the viable tumor portions as target for imaging-guided biopsy. PCT has been used for prediction of treatment outcome, differentiation between post-therapeutic changes and tumor recurrence as well as monitoring patient after radiotherapy and/or chemotherapy. PCT has a role in cervical lymphoma as it may help in detection of response to chemotherapy and early diagnosis of relapsing tumors.

  14. Head-dropping mechanism in traffic control

    Science.gov (United States)

    Liu, Xintong; Yang, Oliver W.

    2004-09-01

    In this paper, we investigate the application of the head dropping policy as a partial solution to the problem of queue oscillation encountered by RED and its variants. With this method, instead of the tail dropping, which is currently used by RED and many other AQM schemes, the TCP source can be informed of the congestion occurring in the bottleneck router a time period earlier. Specifically, that is a time period of the queuing delay. We have compared DH-RED (drop head RED) and DH-BLUE (drop head BLUE) with the current RED and BLUE in a variety of situations and found that the performances such as the queue size stability as well as packet drop rate can be greatly improved.

  15. Corrado Pettenati acting head of ETT

    CERN Multimedia

    2004-01-01

    Following the departure of Juan Antonio Rubio, Corrado Pettenati has been appointed as the acting head of the ETT unit with effect from 1 August. He joined CERN in 1995 as head librarian, reorganizing and modernizing the library before becoming deputy leader of ETT from June 2000 to April 2004. Previously, he worked at the European University Institute in Florence from 1976, developing automated library systems and becoming head of the computer centre in 1985. He has also been a software analyst and a telecommunications specialist. In 2003 he was appointed as member of the steering committee of the Cellule de Coordination Documentaire Nationale pour les Mathématiques de Grenoble, and in 2004 became a member of the EULER - European Libraries and Electronic Resources in Mathematical Sciences - Scientific Advisory Board, based in Germany. He was born in 1946 and graduated with a degree in Electrical Engineering from the Polytechnic in Milan in 1969.

  16. Head pulsations in a centrifugal pump

    Science.gov (United States)

    Boiko, V. S.; Sotnyk, M. I.; Moskalenko, V. V.

    2017-08-01

    This article investigated the factors, which affect to the character of the head pulsations of a centrifugal pump. We investigated the dependence of the shape and depth of these pulsations from the operation mode of the pump. Was determined, that the head pulsations at the outlet of the impeller (pulsations on the blade passing frequency) cause head pulsations at the outlet of the pump, that have the same frequency, but differ in shape and depth. These pulsations depend on the design features of the flow-through part of the pump (from the ratio of hydraulic losses on the friction and losses on the vortex formation). A feature of the researches that were conducted is also the using of not only hydraulic but also electric modeling methods. It allows determining the values of the components of hydraulic losses.

  17. Radiologic head CT interpretation errors in pediatric abusive and non-abusive head trauma patients

    Energy Technology Data Exchange (ETDEWEB)

    Kralik, Stephen F.; Finke, Whitney; Wu, Isaac C.; Ho, Chang Y. [Indiana University School of Medicine, Department of Radiology and Imaging Sciences, Indianapolis, IN (United States); Hibbard, Roberta A.; Hicks, Ralph A. [Indiana University School of Medicine, Department of Pediatrics, Section of Child Protection Programs, Indianapolis, IN (United States)

    2017-07-15

    Pediatric head trauma, including abusive head trauma, is a significant cause of morbidity and mortality. The purpose of this research was to identify and evaluate radiologic interpretation errors of head CTs performed on abusive and non-abusive pediatric head trauma patients from a community setting referred for a secondary interpretation at a tertiary pediatric hospital. A retrospective search identified 184 patients <5 years of age with head CT for known or potential head trauma who had a primary interpretation performed at a referring community hospital by a board-certified radiologist. Two board-certified fellowship-trained neuroradiologists at an academic pediatric hospital independently interpreted the head CTs, compared their interpretations to determine inter-reader discrepancy rates, and resolved discrepancies to establish a consensus second interpretation. The primary interpretation was compared to the consensus second interpretation using the RADPEER trademark scoring system to determine the primary interpretation-second interpretation overall and major discrepancy rates. MRI and/or surgical findings were used to validate the primary interpretation or second interpretation when possible. The diagnosis of abusive head trauma was made using clinical and imaging data by a child abuse specialist to separate patients into abusive head trauma and non-abusive head trauma groups. Discrepancy rates were compared for both groups. Lastly, primary interpretations and second interpretations were evaluated for discussion of imaging findings concerning for abusive head trauma. There were statistically significant differences between primary interpretation-second interpretation versus inter-reader overall and major discrepancy rates (28% vs. 6%, P=0.0001; 16% vs. 1%, P=0.0001). There were significant differences in the primary interpretation-second interpretation overall and major discrepancy rates for abusive head trauma patients compared to non-abusive head trauma

  18. Neuroimaging differential diagnoses to abusive head trauma

    Energy Technology Data Exchange (ETDEWEB)

    Girard, Nadine [AP-HM Timone 2, Department of Neuroradiology, Marseille cedex 05 (France); Aix Marseille University, UMR CNRS 7339, Marseille (France); Brunel, Herve; Dory-Lautrec, Philippe [AP-HM Timone 2, Department of Neuroradiology, Marseille cedex 05 (France); Chabrol, Brigitte [AP-HM Timone, Department of Pediatric Neurology, Marseille (France)

    2016-05-15

    Trauma is the most common cause of death in childhood, and abusive head trauma is the most common cause of traumatic death and morbidity in infants younger than 1 year. The main differential diagnosis of abusive head trauma is accidental traumatic brain injury, which is usually witnessed. This paper also discusses more uncommon diagnoses such as congenital and acquired disorders of hemostasis, cerebral arteriovenous malformations and metabolic diseases, all of which are extremely rare. Diagnostic imaging including CT and MRI is very important for the distinction of non-accidental from accidental traumatic injury. (orig.)

  19. Pocket Proteins Suppress Head and Neck Cancer

    OpenAIRE

    Shin, Myeong-Kyun; Pitot, Henry C.; Lambert, Paul F.

    2012-01-01

    Head and neck squamous cell carcinomas (HNSCC) is a common cancer in humans long known to be caused by tobacco and alcohol use, but now an increasing percentage of HNSCC is recognized to be caused by the same human papillomaviruses (HPVs) that cause cervical and other anogenital cancers. HPV-positive HNSCCs differ remarkably from HPV-negative HNSCCs in their clinical response and molecular properties. From studies in mice, we know that E7 is the dominant HPV oncoprotein in head and neck cance...

  20. Electrochemotherapy of mucosal head and neck tumors

    DEFF Research Database (Denmark)

    Plaschke, Christina Caroline; Gothelf, Anita; Gehl, Julie

    2016-01-01

    with head and neck cancer treated across the mucosal surface with electrochemotherapy. The search resulted in 11 studies with a total of 72 patients. RESULTS: Overall complete response was reported as good, especially in primary small tumors. Side effects were minor in primary tumors whereas large......, recurrent tumors displayed more frequent side effects and some serious adverse events. Design and structure of the studies differed considerably, making general comparisons difficult. CONCLUSION: Few studies concerning electrochemotherapy on mucosal head and neck tumors are available and they are not easily...

  1. [Photodynamic therapy for head and neck cancer

    DEFF Research Database (Denmark)

    Lajer, C.B.; Specht, Lena; Kirkegaard, J.

    2006-01-01

    Photodynamic therapy (PDT) is a new treatment for head and neck cancer. The principle of the treatment is a photochemical reaction initiated by light activation of a photosensitizer, which causes the death of the exposed tissue. This article presents the modes of action of PDT and the techniques...... as well as the clinical procedure. A critical review of the literature is also presented, regarding treatment results of the different techniques and indications for treatments. The possibilities for PDT for head and neck cancer in Denmark are mentioned Udgivelsesdato: 2006/6/5...

  2. Head Trauma in Mixed Martial Arts.

    Science.gov (United States)

    Hutchison, Michael G; Lawrence, David W; Cusimano, Michael D; Schweizer, Tom A

    2014-06-01

    Mixed martial arts (MMA) is a full combative sport with a recent global increase in popularity despite significant scrutiny from medical associations. To date, the empirical research of the risk of head injuries associated with this sport is limited. Youth and amateur participation is growing, warranting investigation into the burden and mechanism of injuries associated with this sport. (1) To determine the incidence, risk factors, and characteristics of knockouts (KOs) and technical knockouts (TKOs) from repetitive strikes in professional MMA; and (2) to identify the mechanisms of head trauma and the situational factors that lead to KOs and TKOs secondary to repetitive strikes through video analysis. Descriptive epidemiology study. Competition data and video records for all KOs and TKOs from numbered Ultimate Fighting Championship MMA events (n = 844) between 2006 to 2012. Analyses included (1) multivariate logistic regression to investigate factors associated with an increased risk of sustaining a KO or TKO secondary to repetitive strikes and (2) video analysis of all KOs and TKOs secondary to repetitive strikes with descriptive statistics. During the study period, the KO rate was 6.4 per 100 athlete-exposures (AEs) (12.7% of matches), and the rate of TKOs secondary to repetitive strikes was 9.5 per 100 AEs (19.1% of matches), for a combined incidence of match-ending head trauma of 15.9 per 100 AEs (31.9% of matches). Logistic regression identified that weight class, earlier time in a round, earlier round in a match, and older age were risk factors for both KOs and TKOs secondary to repetitive strikes. Match significance and previously sustained KOs or TKOs were also risk factors for KOs. Video analysis identified that all KOs were the result of direct impact to the head, most frequently a strike to the mandibular region (53.9%). The average time between the KO-strike and match stoppage was 3.5 seconds (range, 0-20 seconds), with losers sustaining an average of 2

  3. Head first PHP and MySQL

    CERN Document Server

    Beighley, Lynn

    2008-01-01

    If you're ready to create web pages more complex than those you can build with HTML and CSS, Head First PHP & MySQL is the ultimate learning guide to building dynamic, database-driven websites using PHP and MySQL. Packed with real-world examples, this book teaches you all the essentials of server-side programming, from the fundamentals of PHP and MySQL coding to advanced topics such as form validation, session IDs, cookies, database queries and joins, file I/O operations, content management, and more. Head First PHP & MySQL offers the same visually rich format that's turned every title in th

  4. Head Injuries in Professional and Amateur Sports

    OpenAIRE

    Kapp, Spencer

    2017-01-01

    Concussions in sports have become such a large issue in today’s sports society. Each year it seems that we hear more and more about athletes who struggle dealing with head injuries. Athletes continue to get bigger, stronger and faster which brings more excitement to sports. There have been many injuries in contact sports at all levels that not only result in concussions but long-term head injuries that can that cause permanent damage. We have learned and studied so much about the effects that...

  5. Regional myocutaneous flaps for head and neck reconstruction: Experience of a head and neck cancer unit

    Directory of Open Access Journals (Sweden)

    Eyituoyo Okoturo

    2015-01-01

    Full Text Available Background: Pectoralis major myocutaneous pedicle flap and other regional myocutaneous pedicle flaps (RMF, despite the superiority shown by free flaps, have remained relevant in the reconstruction of major head and neck oncologic defects. It has continued to find relevance as the preferred reconstruction of choice in some general head and neck reconstructive applications. While its role has been defined in developed environment, the same cannot be said for developing environment. The aim thus, was to review our experiences with RMFs in head and neck reconstructions, with a view to evaluating the indications and outcomes in a limited opportunity environment with some free flaps expertise. Materials and Methods: This was a retrospective cohort study from records of RMF cases performed for head and neck reconstruction, at the study institution. Eligibility for study inclusion comprised case cohorts with advanced head and neck diseases requiring ablative surgery and reconstruction with pectoralis major flaps and other RMFs. Results: A total of 17 cases were treated with RMFs. 10 were pectoralis major flaps while 7 were other RMFs. The main indications were failed free flaps and financial constraints. No regional pedicle flap failure was recorded; however, complication rate was 35.5% (6/17. Conclusion: Pectoralis major flaps and other RMFs were very reliable option for head and neck reconstruction. Free flap failure and financial constraints were the main indications for RMF reconstruction indications in head and neck reconstruction in a developing environment with some free flap expertise.

  6. Regional Myocutaneous Flaps for Head and Neck Reconstruction: Experience of a Head and Neck Cancer Unit.

    Science.gov (United States)

    Okoturo, Eyituoyo

    2015-01-01

    Pectoralis major myocutaneous pedicle flap and other regional myocutaneous pedicle flaps (RMF), despite the superiority shown by free flaps, have remained relevant in the reconstruction of major head and neck oncologic defects. It has continued to find relevance as the preferred reconstruction of choice in some general head and neck reconstructive applications. While its role has been defined in developed environment, the same cannot be said for developing environment. The aim thus, was to review our experiences with RMFs in head and neck reconstructions, with a view to evaluating the indications and outcomes in a limited opportunity environment with some free flaps expertise. This was a retrospective cohort study from records of RMF cases performed for head and neck reconstruction, at the study institution. Eligibility for study inclusion comprised case cohorts with advanced head and neck diseases requiring ablative surgery and reconstruction with pectoralis major flaps and other RMFs. A total of 17 cases were treated with RMFs. 10 were pectoralis major flaps while 7 were other RMFs. The main indications were failed free flaps and financial constraints. No regional pedicle flap failure was recorded; however, complication rate was 35.5% (6/17). Pectoralis major flaps and other RMFs were very reliable option for head and neck reconstruction. Free flap failure and financial constraints were the main indications for RMF reconstruction indications in head and neck reconstruction in a developing environment with some free flap expertise.

  7. Amplitudes of head movements during putative eye-only saccades.

    Science.gov (United States)

    Oommen, Brian S; Stahl, John S

    2005-12-14

    The mechanisms allowing humans and other primates to dissociate head and eye movements during saccades are poorly understood. A more precise knowledge of head movement behavior during apparent eye-only saccades may provide insight into those mechanisms. We studied the distributions of head amplitude in normal humans. In half of the subjects, these distributions indicated the presence of a population of minor ("residual") head movements during eye-only saccades, distinct from the continuum of head movements generated during frank eye-head saccades. Like full-sized head movements, the residual movements grew in proportion to target eccentricity, indicating their drive is derived from the premotor command for the saccade. Furthermore, their amplitudes related most strongly to the head amplitudes obtained when subjects produced full-sized head movements and were reduced when subjects were instructed to perform exclusively eye-only saccades. Both observations suggest that the drive for residual head movements originates downstream of the point in which the head movement command diverges from the generalized gaze shift command. The results are consistent with a model of head control in which a neural gate prevents the common gaze shift command from reaching the head premotor circuitry whenever an eye-only saccade is desired. However, the gate is either imperfect or the multiple pathways that relay gaze shift signals to the head motor circuitry allow for the gate to be circumvented. The results underscore the need for physiological studies to probe neuronal activity related to neck activation during eye-only saccades.

  8. Eye-Head Coordination for Visual Cognitive Processing

    Science.gov (United States)

    Fang, Yu; Nakashima, Ryoichi; Matsumiya, Kazumichi; Kuriki, Ichiro; Shioiri, Satoshi

    2015-01-01

    We investigated coordinated movements between the eyes and head (“eye-head coordination”) in relation to vision for action. Several studies have measured eye and head movements during a single gaze shift, focusing on the mechanisms of motor control during eye-head coordination. However, in everyday life, gaze shifts occur sequentially and are accompanied by movements of the head and body. Under such conditions, visual cognitive processing influences eye movements and might also influence eye-head coordination because sequential gaze shifts include cycles of visual processing (fixation) and data acquisition (gaze shifts). In the present study, we examined how the eyes and head move in coordination during visual search in a large visual field. Subjects moved their eyes, head, and body without restriction inside a 360° visual display system. We found patterns of eye-head coordination that differed those observed in single gaze-shift studies. First, we frequently observed multiple saccades during one continuous head movement, and the contribution of head movement to gaze shifts increased as the number of saccades increased. This relationship between head movements and sequential gaze shifts suggests eye-head coordination over several saccade-fixation sequences; this could be related to cognitive processing because saccade-fixation cycles are the result of visual cognitive processing. Second, distribution bias of eye position during gaze fixation was highly correlated with head orientation. The distribution peak of eye position was biased in the same direction as head orientation. This influence of head orientation suggests that eye-head coordination is involved in gaze fixation, when the visual system processes retinal information. This further supports the role of eye-head coordination in visual cognitive processing. PMID:25799510

  9. 76 FR 70009 - Head Start Program

    Science.gov (United States)

    2011-11-09

    ..., health, nutritional, and social needs of the children and families they serve and meet program and... administered by the Office of Head Start (OHS), Administration for Children and Families (ACF), Department of... that indicate the great importance of the early years of a child's growth and development. On December...

  10. Insta-Head: An Instant Headgear Tube

    Directory of Open Access Journals (Sweden)

    Rajesh B Kuril

    2011-01-01

    Full Text Available Specialized headgear tubes are required for fabrication of appliances, such as activator-headgear and twin-block with headgear. The common problems with these tubes are that they need to be purchased beforehand and they are expensive. The present article describes the chairside fabrication of a simple, inexpensive headgear tube (insta-head without the need of any specialized armamentarium.

  11. Association between head circumference and body size

    NARCIS (Netherlands)

    Geraedts, E.J.; Dommelen, P. van; Caliebe, J.; Visser, R.; Ranke, M.B.; Buuren, S. van; Wit, J.M.; Oostdijk, W.

    2011-01-01

    Background/Aims: Studies on the association between head circumference (HC) and height or weight have shown variable results. Methods: Using data from the Dutch nationwide survey performed in 1997 (n = 14,500), we calculated correlations for different ages, and fitted a regression model for the

  12. determination of head for small hydropower development

    African Journals Online (AJOL)

    eobe

    by hydraulic structures without inherent energy losses. But ideal systems only exist in mathematical models and do not provide an accurate portrayal of a real model. The designer of a hydroelectric power system must therefore account for head losses in the penstock when determining the actual amount of electric power ...

  13. 49 CFR 214.113 - Head protection.

    Science.gov (United States)

    2010-10-01

    ... impact, or from falling or flying objects, or from electrical shock and burns, shall be provided and... and penetration of falling and flying objects, or from high voltage electrical shock and burns shall conform to the national consensus standards for industrial head protection (American National Standards...

  14. Fibromatosis of the head and neck

    NARCIS (Netherlands)

    Plaat, B. E.; Balm, A. J.; Loftus, B. M.; Gregor, R. T.; Hilgers, F. J.; Keus, R. B.

    1995-01-01

    Fibromatosis is a locally infiltrative fibrous tissue proliferation with a tendency to recur locally. From a large series of head and neck patients treated between 1977 and 1994 in our institute, we retrieved the records of nine adult patients diagnosed with this disease. They serve as examples to

  15. Unilateral otolith centrifugation by head tilt

    NARCIS (Netherlands)

    Winters, S.M.; Bos, J.E.; Klis, S.F.L.

    2014-01-01

    BACKGROUND: To test for otolith asymmetries, several studies described horizontal translation of the body and head en bloc during fast vertical axis rotation. This stimulus causes one otolithic organ to rotate on-axis, and the other to experience centripetal acceleration. OBJECTIVE: To test a new,

  16. Addressing Tooth Decay in Head Start Children

    Science.gov (United States)

    Knowlden, Adam P.; Hill, Lawrence F.; Alles-White, Monica L.; Cottrell, Randall R.

    2012-01-01

    Tooth decay is the most prevalent chronic disease of childhood. Oral health education and dental services are crucial to reducing the number of children afflicted with dental cavities. Due to limited access to preventative care, Head Start children are particularly vulnerable to tooth decay. This article outlines practical implications of a…

  17. Nutrition in Patients with Head Trauma

    Directory of Open Access Journals (Sweden)

    Burcu Totur

    2013-01-01

    Full Text Available The need of energy increases by 40% in patients with a head trauma, when compared to people who are living a normal life. This ratio reaches to 200% in some cases. It is important to give a nutrition support which can satisfy the energy need resulted from the hypermetabolic and hypercatabolic states and that is enough to help to fix the immunologic state and achieve a better result in healing the injury. When oral nutrition is not possible in the patient with a head trauma, their energy need is satisfied through enteral and parenteral nutrition. Though parenteral nutrition had held an important role in feeding patients with head trauma, enteral nutrition is applied much more widely today. Enteral and parenteral nutrition both has their own advantages and disadvantages. In the clinical and laboratory studies that had been held, it was found that enteral nutrition improved the systemic immunity, decreased the incidence of the major infectious complications, decreased the metabolic response to trauma, protected the intestinal mucosa, and protected the ecologic balance of the microflora. In this article, it is investigated through the importance of the feeding in patients with a head trauma and reasons to chose enteral nutrition

  18. Head injuries in helmeted child bicyclists.

    Science.gov (United States)

    Grimard, G.; Nolan, T.; Carlin, J. B.

    1995-01-01

    OBJECTIVE: To determine the characteristics and the severity of head and facial injuries to helmeted child bicyclists, and whether the helmet contributed to the injury, and to study factors related to bicycle accidents. DESIGN: Retrospective review of two case series. Children sustaining head injury while not wearing helmets were studied as a form of reference group. SETTING: Large paediatric teaching hospital. SUBJECTS: 34 helmeted child bicyclists and 155 non-helmeted bicyclists, aged 5-14 years. MAIN OUTCOME MEASURES: Number of injuries, type of injuries, injury severity score, deaths, and accident circumstances. RESULTS: 79% of the head injuries of the helmeted child group were mild and two thirds of these had facial injuries. Children in the helmet group were in a greater proportion of bike-car collisions than the no helmet group and at least 15% of the helmets were lost on impact. There were no injuries secondary to the helmet. CONCLUSIONS: Most of the head injuries sustained by the helmeted children were of mild severity and there was no evidence to suggest that the helmet contributed to injury. Nevertheless, consideration should be given to designing a facial protector for the bicycle helmet and to improvement of the fastening device. PMID:9345988

  19. Visual perception of axes of head rotation

    NARCIS (Netherlands)

    Arnoldussen, D.M.; Goossens, J.; Berg, A.V. van den

    2013-01-01

    Registration of ego-motion is important to accurately navigate through space. Movements of the head and eye relative to space are registered through the vestibular system and optical flow, respectively. Here, we address three questions concerning the visual registration of self-rotation. (1)

  20. Nested head-tail Vlasov solver

    Directory of Open Access Journals (Sweden)

    A. Burov

    2014-02-01

    Full Text Available Nested head-tail is a Vlasov solver for transverse oscillations in multibunch beams. It takes into account azimuthal, radial, coupled-bunch, and beam-beam degrees of freedom affected by arbitrary dipole wakes, feedback damper,beam-beam effects and Landau damping.