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1

Large-Head Metal-on-Metal Total Hip Arthroplasty Using the Durom Acetabular Component at Minimum 1Year Interval  

Microsoft Academic Search

Large-head metal-on-metal total hip arthroplasty represents novel technology, and outcome data are lacking. We prospectively compared the performance of a nonmodular metal-on-metal acetabular component (Durom; Zimmer, Warsaw, IN) with a modular titanium component (Trilogy, Zimmer). All Durom components placed at our institution with minimum 1-year follow up (n = 63) were compared with an age- and sex-matched Trilogy control group

Richard L. Illgen II; John P. Heiner; Matthew W. Squire; David N. Conrad

2010-01-01

2

Early failures in large head metal-on-metal total hip arthroplasty.  

PubMed

Concerns have recently been raised about large head metal-on-metal total hip arthroplasties (LDH THA). Metal ion release due to wear may cause osteolysis, pseudotumours and necrosis. In addition, fixation of certain acetabular components is thought to be suboptimal. We present the short term outcome of the Durom LDH THA. Retrospectively, a consecutive series of 64 implants in 60 patients was analysed with a mean follow-up of 37 months. Clinical and radiological evaluation was performed on a regular basis, followed by additional evaluations when indicated. The 10-year revision percentage was calculated and compared with National Institute for Health and Clinical Excellence (NICE) standards. Six patients (six hips) underwent cup revision (9%). Four of these cups showed no or minimal bone fixation. Three patients had a pseudotumour. In two revision cases, ALVAL (aseptic lymphocyte-dominated vasculitis-associated lesion) was present. Lack of bone ingrowth and the presence of ARMD (adverse reaction to metal debris) seem to contribute to a high failure rate of the Durom LDH THA. The predicted ten-year revision rate of 14.2% (95% CI 5.6-22.8) is, given the broad confidence interval, not significantly outside NICE recommended standards. However, it is not clear which factors, if any, predict implant failure. Therefore, we do not advocate the use of this implant. PMID:23233178

Althuizen, Martje N R; V Hooff, Miranda L; v d Berg-v Erp, Saskia H M; V Limbeek, Jacques; Nijhof, Marc W

2012-01-01

3

Serum metal ion concentrations after unilateral vs bilateral large-head metal-on-metal primary total hip arthroplasty.  

PubMed

It is unknown if the presence of bilateral well-functioning large-head metal-on-metal (MOM) total hip arthroplasties (THAs) leads to higher serum metal ion concentrations than unilateral MOM THA. Elevated levels (chromium, 17 ?g/L; cobalt, 19 ?g/L) have been associated with poorly functioning MOM THA with metallosis. Fourteen patients having undergone bilateral and 25 patients having undergone unilateral large-head primary MOM THA were compared. Harris Hip Scores, University of California Los Angeles activity scores, radiographs, serum creatinine, and serum cobalt and chromium levels were obtained. Only cobalt ion levels were significantly higher in the bilateral group than in the unilateral group (1.8 ?g/L vs 1.0 ?g/L, P = .029). Comparatively, this magnitude is clinically rather low because ion levels did not approach those associated with metallosis in either group. We conclude that although patients with well-functioning bilateral MOM THA may have slightly higher cobalt levels, neither cobalt nor chromium levels approach those seen in poorly functioning MOM THA with metallosis. PMID:21570800

Pelt, Christopher E; Bergeson, Adam G; Anderson, Lucas A; Stoddard, Gregory J; Peters, Christopher L

2011-12-01

4

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

Microsoft Academic Search

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

Wierd P Zijlstra; Nanne Bos; Jos JAM van Raaij

2008-01-01

5

No association between serum metal ions and implant fixation in large-head metal-on-metal total hip arthroplasty.  

PubMed

Background - The mechanism of failure of metal-on-metal (MoM) total hip arthroplasty (THA) has been related to a high rate of metal wear debris, which is partly generated from the head-trunnion interface. However, it is not known whether implant fixation is affected by metal wear debris. Patients and methods - 49 cases of MoM THA in 41 patients (10 women) with a mean age of 52 (28-68) years were followed with stereoradiographs after surgery and at 1, 2, and 5 years to analyze implant migration by radiostereometric analysis (RSA). Patients also participated in a 5- to 7-year follow-up with measurement of serum metal ions, questionnaires (Oxford hip score (OHS) and Harris hip score (HHS)), and measurement of cup and stem positions and systemic bone mineral density. Results - At 1-2 years, mean total translation (TT) was 0.04 mm (95% CI: -0.07 to 0.14; p = 0.5) for the stems; at 2-5 years, mean TT was 0.13 mm (95% CI: -0.25 to -0.01; p = 0.03), but within the precision limit of the method. For the cups, there was no statistically significant TT or total rotation (TR) at 1-2 and 2-5 years. At 2-5 years, we found 4 cups and 5 stems with TT migrations exceeding the precision limit of the method. There was an association between cup migration and total OHS < 40 (4 patients, 4 hips; p = 0.04), but there were no statistically significant associations between cup or stem migration and T-scores < -1 (n = 10), cup and stem positions, or elevated serum metal ion levels (> 7µg/L (4 patients, 6 hips)). Interpretation - Most cups and stems were well-fixed at 1-5 years. However, at 2-5 years, 4 cups and 5 stems had TT migrations above the precision limits, but these patients had serum metal ion levels similar to those of patients without measurable migrations, and they were pain-free. Patients with serum metal ion levels > 7 µg/L had migrations similar to those in patients with serum metal ion levels < 7 µg/L. Metal wear debris does not appear to influence the fixation of hip components in large-head MoM articulations at medium-term follow-up. PMID:24847790

Hjorth, Mette Holm; Søballe, Kjeld; Jakobsen, Stig Storgaard; Lorenzen, Nina Dyrberg; Mechlenburg, Inger; Stilling, Maiken

2014-08-01

6

Does bearing size influence metal ion levels in large-head metal-on-metal total hip arthroplasty? A comparison of three total hip systems  

PubMed Central

Background The purpose of the study was twofold: first, to determine whether there is a statistically significant difference in the metal ion levels among three different large-head metal-on-metal (MOM) total hip systems. The second objective was to assess whether position of the implanted prostheses, patient demographics or factors such as activity levels influence overall blood metal ion levels and whether there is a difference in the functional outcomes between the systems. Methods In a cross-sectional cohort study, three different metal-on-metal total hip systems were assessed: two monoblock heads, the Durom socket (Zimmer, Warsaw, IN, USA) and the Birmingham socket (Smith and Nephew, Memphis, TN, USA), and one modular metal-on-metal total hip system (Pinnacle, Depuy Orthopedics, Warsaw, IN, USA). Fifty-four patients were recruited, with a mean age of 59.7 years and a mean follow-up time of 41 months (12 to 60). Patients were evaluated clinically, radiologically and biochemically. Statistical analysis was performed on all collected data to assess any differences between the three groups in terms of overall blood metal ion levels and also to identify whether there was any other factor within the group demographics and outcomes that could influence the mean levels of Co and Cr. Results Although the functional outcome scores were similar in all three groups, the blood metal ion levels in the larger monoblock large heads (Durom, Birmingham sockets) were significantly raised compared with those of the Pinnacle group. In addition, the metal ion levels were not found to have a statistically significant relationship to the anteversion or abduction angles as measured on the radiographs. Conclusions When considering a MOM THR, the use of a monoblock large-head system leads to higher elevations in whole blood metal ions and offers no advantage over a smaller head modular system.

2014-01-01

7

Cementless large-head metal-on-metal total hip arthroplasty in patients younger than 60 years—A multicenter early result  

Microsoft Academic Search

Large-head metal-on-metal total hip arthroplasty has the theoretical advantages of less wear and better range of motion than traditional polyethylene bearings and seems to be a better choice for young and active patients. We conducted a retrospective study and reported the early results of using such prostheses in 59 patients (70 hips) with a mean age of 43.1 years (range,

Po-Ting Wu; Chih-Jen Wang; Cheng-Yo Yen; Ji-Shen Jian; Kuo-An Lai

8

Material loss at the taper junction of retrieved large head metal-on-metal total hip replacements.  

PubMed

It has been speculated that material loss, either as corrosion or wear, at the head-stem taper junction is implicated in the high revision rates reported for metal-on-metal total hip replacements. We measured the volume of material loss from the taper and bearing surfaces of retrieved devices, and investigated the associations with blood metal ion levels and the diagnosis of a cystic or solid pseudotumor. The median volumes of material lost from the female and male taper surfaces were 2.0 and 0.29?mm(3) , respectively, while the median volumes of wear from the cup and head bearing surfaces were 1.94 and 3.44?mm(3) , respectively. Material loss from the female taper was similar to that from the acetabular bearing surface (p?=?0.55), but significantly less than that from the femoral bearing surface (p?

Matthies, Ashley K; Racasan, Radu; Bills, Paul; Blunt, Liam; Cro, Suzie; Panagiotidou, Anna; Blunn, Gordon; Skinner, John; Hart, Alister J

2013-11-01

9

A prospective metal ion study of large-head metal-on-metal bearing: a matched-pair analysis of hip resurfacing versus total hip replacement.  

PubMed

The current study measured ion release among large-head metal-on-metal hip bearings. Twenty-six patients with a modular, Profemur® TL with A-Class® big femoral head total hip replacement were matched (gender, femoral size, BMI) with a group of 26 patients with the Conserve® Plus implant hip resurfacing. Compared with HR patients, THR patients had higher median serum cobalt ion levels at 6 months (3.26 vs 1.12 ?g/L, P = .002) 1 year (4.51 vs 1.02, P = .002), and 2 years (3.77 vs 1.22, P<.001) following surgery. No differences in chromium ions were observed. Further research is required to determine the clinical significance of elevated serum cobalt ions. PMID:21435499

Beaulé, Paul E; Kim, Paul R; Hamdi, Amre; Fazekas, Anna

2011-04-01

10

A comparison of leg length and femoral offset discrepancies in hip resurfacing, large head metal-on- metal and conventional total hip replacement: a case series  

PubMed Central

Background A discrepancy in leg length and femoral offset restoration is the leading cause of patient dissatisfaction in hip replacement surgery and has profound implications on patient quality of life. The aim of this study is to compare biomechanical hip reconstruction in hip resurfacing, large-diameter femoral head hip arthroplasty and conventional total hip replacement. Method Sixty patient's post-operative radiographs were reviewed; 20 patients had a hip resurfacing (HR), 20 patients had a Large Head Metal-on-metal (LHM) hip replacement and 20 patients had a conventional small head Total Hip Replacement (THR). The leg length and femoral offset of the operated and unoperated hips were measured and compared. Results Hip resurfacing accurately restored hip biomechanics with no statistical difference in leg length (P = 0.07) or femoral offset (P = 0.95) between the operated and non-operative hips. Overall HR was superior for reducing femoral offset discrepancies where it had the smallest bilateral difference (-0.2%, P = 0.9). The traditional total hip replacement was least effective at restoring the hip anatomy. Conclusion The use of a larger-diameter femoral head in hip resurfacing does not fully account for the superior biomechanical restoration, as LHM did not restore femoral offset as accurately. We conclude that restoration of normal hip biomechanics is best achieved with hip resurfacing.

2011-01-01

11

Metal-on-Metal Total Hip Arthroplasty  

Microsoft Academic Search

Although metal-on-metal total hip arthroplasty (MOM THA) has been used for over 3 decades, substantial improvements in manufacturing and design have led to improved durability with modern implants. Reported advantages of the use of MOM THA include very low wear and subsequent osteolysis, increased range of motion to impingement secondary to the availability of larger diameter femoral heads, and the

Raymond H. Kim; Douglas A. Dennis; Joshua T. Carothers

2008-01-01

12

Metal-on-Metal Total Hip Replacement  

Microsoft Academic Search

Second-generation metal-on-metal (M\\/M) total hip replacements were introduced into clinical use in the late 1980s and demonstrate equivalent survivorship to conventional metal-on-polyethylene prostheses. Wear rates are comparable to those of first-generation designs that survived for a long time in the body. Biological effects from metal ions remain a concern. Patients with both first- and second-generation M\\/M hips have higher levels

John H. Dumbleton; Michael T. Manley

2005-01-01

13

Metal-on-Metal Total Hip Arthroplasty: The Concerns  

Microsoft Academic Search

The metal-on-metal bearing couple in having a resurgence in clinical applications seen in both total hip resurfacing technologies. The most noteworthy advantage of a metal-on-metal implant is the improved wear characteristics seen both in vitro on wear simulators and in vivo with retrieved implants. All bearings have disadvantages, and a metal-on-metal bearing is no exception. Concerns exist regarding the generation

S. J. MacDonald

14

The Correlation of Serum Metal Ions with Functional Outcome Scores at Three-to-Six Years following Large Head Metal-on-Metal Hip Arthroplasty  

PubMed Central

Based on success of hip resurfacing, large head Metal on Metal (MoM) hip arthroplasty has gained significant popularity in recent years. There are growing concerns about metal ions related soft tissue abnormalities. The aim of this study was to define a correlation of metal ions with various functional outcome scores following large head MoM hip arthroplasty. Consecutive cohort of 70 patients (76 hips) with large head MoM hip arthroplasty using SL-Plus femoral stem and Cormet acetabular component were prospectively followed up. An independent observer assessed the patients which included serology for metal ion levels and collection of Oxford Hip, Harris hip, WOMAC, SF-36 & modified UCLA scores. Median serum cobalt and chromium levels were 3.10??g/L (0.35–62.92) and 4.21??g/L (0.73–69.27) with total of median 7.30??g/L (2.38–132.19). The median Oxford, Harris, WOMAC, SF-36 and modified UCLA scores were 36 (6–48), 87 (21–100), 36 (24–110), 104 (10–125), and 3 (1–9), respectively. Seventeen patients had elevated serum cobalt and chromium levels ?7??g/L. There was no significant correlation between serum metal ion levels with any of these outcome scores. We recommend extreme caution during follow up of these patients with large head MoM arthroplasty.

Patange Subbarao, Sheethal Prasad; Malek, Ibrahim A.; Mohanty, Khitish; Thomas, Phillip; John, Alun

2013-01-01

15

Metal-on-metal total hip arthroplasty: the concerns.  

PubMed

The metal-on-metal bearing couple is having a resurgence in clinical applications seen in total hip and hip resurfacing technologies. The most noteworthy advantage of a metal-on-metal implant is the improved wear characteristics seen in vitro on wear simulators and in vivo with retrieved implants. All bearings have disadvantages, and a metal-on-metal bearing is no exception. Concerns exist regarding the generation of metal ions seen in the blood and urine of patients with metal-on-metal implants. These elevated metal ions have theoretical, although not proven, risks related to carcinogenic and biologic concerns. Additionally, concerns exist regarding hypersensitivity, increased incidence of instability and increased costs. Specific patient selection issues arise with metal-on-metal implants. The current generation of implants has only early and mid-term results available, with no long-term series yet published. Therefore, although a metal-on-metal bearing may be considered a viable alternative to either polyethylene or ceramic implants, outstanding and unresolved issues continue to exist with this bearing, as they do with the alternatives. PMID:15577471

MacDonald, S J

2004-12-01

16

Management of failed metal-on-metal total hip arthroplasty  

PubMed Central

The theoretical advantages of metal-on-metal (MOM) bearing couples in total hip arthroplasty (THA) have been recently balanced by concerns regarding adverse local and systemic effects. Higher than anticipated early revision rates have been reported by several joint registries. Failed MOM hips present with a spectrum of symptoms and findings and traditional methods of failure must be considered in addition to the failure modes that appear to be unique to the MOM bearing couple. Metal hypersensitivity and soft tissue immune reactions remain incompletely understood and require careful ongoing study. The tools available to evaluate MOM THAs and the indications for revision surgery remain to be defined. Outcomes following revision of MOM hips appear to depend on appropriate evaluation, early identification, and appropriate surgical management.

Griffin, Justin W; D'Apuzzo, Michele; Browne, James A

2012-01-01

17

Metal-on-Metal Total Hip Resurfacing Arthroplasty  

PubMed Central

Executive Summary Objective 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. Clinical Need 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. The Technology 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 femoral head reduces the chance of dislocation, so that rates of dislocation are less than those with conventional THR. Second, the range of motion with hip resurfacing arthroplasty is higher than that achieved with conventional THR. A variety of MOM hip resurfacing implants are used in clinical practice. Six MOM hip resurfacing implants have been issued licences in Canada. Review Strategy A search of electronic bibliographies (OVID Medline, Medline In-Process and Other Non-Indexed Citations, Embase, Cochrane CENTRAL and DSR, INAHTA) was undertaken to identify evidence published from Jan 1, 1997 to October 27, 2005. The search was limited to English-language articles and human studies. The literature search yielded 245 citations. Of these, 11 met inclusion criteria (9 for effectiveness, 2 for safety). The result of the only reported randomized controlled trial on MOM hip resurfacing arthroplasty could not be included in this assessment, because it used a cemented acetabular component, whereas in the new generation of implants, a cementless acetabular component is used. After omitting this publication, only case series remained. Summary of Findings   Health Outcomes The Harris hip score and SF-12 are 2 measures commonly used to report health outcomes in MOM hip resurfacing arthroplasty studies. Other scales used are the Oxford hip score and the University of California Los Angeles hip score. The case series showed that the mean revision rate of MOM hip resurfacing arthroplasty is 1.5% and the incidence of femoral neck fracture is 0.67%. Across all studies, 2 cases of osteonecrosis were reported. Four studies reported improvement in Harris hip scores. However, only 1 study reported a statistically significant improvement. Three studies reported improvement in SF-12 scores, of which 2 reported a significant improvement. One study reported significant improvement in UCLA hip score. Two studies reported postoperative Oxford hip scores, but no preoperative values were reported. None of the reviewed studies r

2006-01-01

18

Metal-on-metal total hip arthroplasty: causes and high incidence of early failure.  

PubMed

Early failures of metal-on-metal total hip arthroplasty (THA) occur due to aseptic loosening, metal hypersensitivity reactions, pseudotumor formation, and component seizing. The purpose of this study was to investigate the timing, common modes of failure, clinical outcomes, and incidence of metal-on-metal THA revisions. A review was performed of 80 patients who underwent revision of a failed metal-on-metal THA for any reason. The most common reason for metal-on-metal failure was aseptic acetabular loosening, with a rate of 56.25% (45/80 patients). Early failure of metal-on-metal THAs was noted, with 78% of these revisions being performed within 2 years of the index operation and 92.5% within 3 years. Furthermore, 13% of patients experienced significant localized soft tissue reactions. Mean preoperative Harris Hip Score was 42.35 ± 14.24 and mean postoperative Harris Hip Score was 66.5 ± 23.2 (range, 9.55-95.4), with an average follow-up of 438 ± 492 days (range, 40-2141), or 1.2 years.It is imperative that clinicians be cognizant of the fact that the proposed advantages of metal-on-metal THA are not without potential detrimental sequelae. This article proposes an algorithm to aid in diagnosing the etiology of a painful metal-on-metal THA, as well as 2 classification schemes regarding metal-on-metal THA complications to help direct treatment. PMID:22784892

Fabi, David; Levine, Brett; Paprosky, Wayne; Della Valle, Craig; Sporer, Scott; Klein, Gregg; Levine, Harlan; Hartzband, Mark

2012-07-01

19

Serum metal ion levels after second-generation metal-on-metal total hip arthroplasty  

Microsoft Academic Search

Introduction  Metal-on-metal bearings for total hip arthroplasty are increasing in popularity. However, metal ion toxicity, metal hypersensitivity,\\u000a and metal carcinogenicity are the causes concern for patients with metal-on-metal hip replacement. We investigated serum levels\\u000a of cobalt and chromium ions in patients with successfully implanted second-generation metal-on-metal total hip arthroplasty\\u000a (THA) using PINNACLE-A (DePuy, Warsaw, IN, USA).\\u000a \\u000a \\u000a \\u000a \\u000a Materials and methods  Thirty-three patients underwent

Takao Imanishi; Masahiro Hasegawa; Akihiro Sudo

2010-01-01

20

The evolution and modern use of metal-on-metal bearings in total hip arthroplasty.  

PubMed

Metal-on-metal bearings have been used in total hip arthroplasty for decades. Because younger patients with higher physical demands are now being treated with hip arthroplasty, the popularity and use of metal-on-metal bearings has increased over the past 10 years. New concerns, however, have emerged regarding the percentage of patients with a hypersensitivity reaction or pseudotumor formation after arthroplasty with these bearings. These concerns have raised questions concerning long-term outcomes for patients treated with metal-on-metal bearings. It is important for orthopaedic surgeons to review these issues so that better educated decisions can be made in treating their patients. PMID:21553777

Gonzalez, Mark H; Carr, Ryan; Walton, Sharon; Mihalko, William M

2011-01-01

21

Large-diameter metal-on-metal total hip arthroplasties: a page in orthopedic history?  

PubMed

Large-diameter metal-on-metal (MoM) bearings evolved from the success of hip resurfacing. These implants were used in revision surgery in cases with well-fixed acetabular cups but loose or failed femoral stems, to avoid cup revision. Early data showed low rates of dislocation and potentially low wear profiles due to better fluid film lubrication. The risk of impingement was also thought to be low due to the increased head-neck ratio. Subsequently large-diameter MoM heads gained popularity in primary hip replacement. Recent data has emerged on the unacceptably high revision rates among patients with large-diameter MoM total hip arthroplasties (THAs), high blood levels of metal ions, and adverse tissue reactions. The head-neck (cone-taper) modular interface probably represents the weak link in large metal heads that have been used on conventional tapers. Increased torque of the large head, micromotion, and instability at the cone-taper interface, synergistic interactions between corrosion and wear, edge loading, low clearance, and psoas impingement are the likely causes for early failure of these prostheses. PMID:23529961

Singh, Gurpal; Meyer, Heiko; Ruetschi, Marcel; Chamaon, Kathrin; Feuerstein, Bernd; Lohmann, Christoph H

2013-11-01

22

The Clinical Performance of Metal-on-Metal as an Articulation Surface in Total Hip Replacement  

PubMed Central

The metal-on-metal articulations in total hip arthroplasty (THA) were widely used between 1960 and 1975. The McKee-Farrar and other first-generation prostheses failed at a high rate because impingement caused early component loosening. The problem of early component loosening was corrected by improved component design and better manufacturing quality. Second-generation metal-on-metal total hip replacements have experienced short and medium-term success as assessed by Harris Hip Scores and patient selfassessment. The combined annual linear wear of the metal-on-metal femoral head and acetabular insert is less than 10 mm and osteolysis has only rarely been observed in association with well-fixed metal-on-metal total hip replacements. Hypersensitivity is not a common cause of loosening with second-generation hip replacements and remains to be proven as a definitive diagnosis in unusual cases of unexplained pain. More than 40 years of use has demonstrated no increase in the incidence of renal failure or cancer in patients with metal-on-metal total hip replacements. The scientific evidence of the results using the metal-on-metal articulations would recommend its continued use in any patient who does not have compromised renal function.

Long, William T

2005-01-01

23

Femoral Head Size Does Not Affect Ion Values in Metal-on-Metal Total Hips  

Microsoft Academic Search

Background  Metal-on-metal articulations can release substantial amounts of particles containing cobalt and chromium into the surrounding\\u000a milieu, causing concern for cellular toxicity and adverse local soft tissue reactions. The diameter of the femoral head has\\u000a been one of the variables that inversely affects wear of metal-on-metal total hip arthroplasty (THA). The oxidative stress\\u000a of increased metal ions can be measured with

Mitchell Bernstein; Alan Walsh; Alain Petit; David J. Zukor; John Antoniou

2011-01-01

24

Cementless Metasul Metal-On-Metal Total Hip Arthroplasties at 13 Years  

Microsoft Academic Search

Second-generation metal-on-metal bearings have been used since the late 1980s as alternative bearings to eliminate aseptic loosening due to polyethylene wear. The aim of the present study was to evaluate the long-term results of a series of Metasul (Zimmer GmbH, Winterthur, Switzerland) metal-on-metal total hip arthroplasty (THA). One hundred forty-nine cementless THAs with a 28-mm Metasul articulation were performed in

Filippo Randelli; Lorenzo Banci; Alessandro D'Anna; Ornella Visentin; Gianni Randelli

25

Metal-on-Metal vs Metal-on-Improved Polyethylene Bearings in Total Hip Arthroplasty  

Microsoft Academic Search

Major weaknesses of total hip arthroplasty (THA) in the 20th century were polyethylene wear and dislocation. Efforts to improve THA took several directions including improvement of polyethylene and use of metal-on-metal (MoM) articulations. Metal-on-metal articulations showed excellent early results, but concerns mount over hypersensitivity and increasing failure. This study compares our experience with MoM and metal-on-improved polyethylene (MoIP) bearings in

Ryan G. Molli; Adolph V. Lombardi; Keith R. Berend; Joanne B. Adams; Michael A. Sneller

2011-01-01

26

Long-Term Results of a Contemporary Metal-on-Metal Total Hip Arthroplasty  

Microsoft Academic Search

The goal of the study was to evaluate the long-term results of a metal-on-metal articulation. We evaluated the results and histologic findings in patients who had undergone revision. One hundred total hip arthroplasties with a Lubrimet metal-on-metal articulation (Smith and Nephew, Rotkreuz, Switzerland) were implanted in 99 consecutive unselected patients in 1995 and 1996, and the results were prospectively analyzed

Daniel R. P. Neumann; Christoph Thaler; Wolfgang Hitzl; Monika Huber; Thomas Hofstädter; Ulrich Dorn

2010-01-01

27

Catastrophic Failure of a Metal-on-Metal Total Hip Arthroplasty Secondary to Metal Inlay Dissociation  

Microsoft Academic Search

Metal-on-metal bearing surfaces in total hip arthroplasty have been recently shown to have acceptable survivorship properties (J Bone Joint Surg Am. 2006;88:1183; J Bone Joint Surg Am. 2006;88:1173), and they have certain advantages and disadvantages when compared to conventional metal-on-polyethylene bearing surfaces. Like traditional metal-on-polyethylene bearings, these metal-on-metal implants may also suffer from catastrophic failure. This case report represents an

Michael J. Alaia; Alan J. Dayan

2011-01-01

28

Painful Metal-on-Metal Total Hip Arthroplasty  

Microsoft Academic Search

Two patients were evaluated for the possibility of hypersensitivity to a Metasul articulation (Centerpulse, Austin, Tex) coupled with total hip arthroplasty. Serum was tested with a lymphocyte proliferation assay, and the capsular tissues from the hip were examined for perivascular lymphocytes. The diagnosis of hypersensitivity to Metasul could not be confirmed in these patients, and ultimately, the painful hip arthroplasties

Cambize Shahrdar; Pat Campbell; Joseph Mirra; Lawrence D. Dorr

2006-01-01

29

Catastrophic failure of a metal-on-metal total hip arthroplasty secondary to metal inlay dissociation.  

PubMed

Metal-on-metal bearing surfaces in total hip arthroplasty have been recently shown to have acceptable survivorship properties (J Bone Joint Surg Am. 2006;88:1183; J Bone Joint Surg Am. 2006;88:1173), and they have certain advantages and disadvantages when compared to conventional metal-on-polyethylene bearing surfaces. Like traditional metal-on-polyethylene bearings, these metal-on-metal implants may also suffer from catastrophic failure. This case report represents an unusual situation in a 57-year-old man in which dissociation of a metal inlay in a metal-on-metal total hip arthroplasty resulted in articulation of the inferior aspect of the inlay with the femoral neck, leading to femoral neck notching, extensive periprosthetic soft tissue metallosis, osteolysis, and subsequent prosthetic catastrophic failure. PMID:20875944

Alaia, Michael J; Dayan, Alan J

2011-09-01

30

Early results of metal on metal articulation total hip arthroplasty in young patients  

Microsoft Academic Search

We report our early experience of 20 cases of metal on metal articulation total hip arthroplasty in 19 young patients. Avascular necrosis of the femoral head (63%) was the commonest diagnosis for patients undergoing this procedure, followed by osteoarthritis (21%). In general, most of the patients were young and physically active with an average age of 43.1 years (range, 25

J. A. Mohamad; M. K. Kwan; A. M. Merican; A. A. Abbas; Z. H. Kamari; M. K. Hisa; Z. Ismail; R. M. Idrus

2004-01-01

31

Infection or Allergy in the Painful Metal-on-Metal Total Hip Arthroplasty?  

Microsoft Academic Search

Metal-on-metal articulations are increasingly used in total hip arthroplasty. Patients can be sensitive to metal ions produced by the articulation and present with pain or early loosening. Infection must be excluded. Correct diagnosis before revision surgery is crucial to implant selection and operation planning. There is no practical guide in the literature on how to differentiate between allergy and infection

Leela C. Biant; Warwick J. M. Bruce; Hans van der Wall; William R. Walsh

2010-01-01

32

Serum Chromium Levels Before and After Revision Surgery for Loosened Metal-On-Metal Total Hip Arthroplasty  

Microsoft Academic Search

We investigated the changes of serum chromium levels before and after revision surgery in 10 patients (1 male and 9 females) who underwent exchange of a metal-on-metal articulation for a metal-on-polyethylene component because of aseptic loosening of a metal-on-metal total hip prosthesis. Of the 10 patients, 2 had bilateral metal-on-metal total hip arthroplasty. In the 8 patients who had no

Katsuhiko Maezawa; Masahiko Nozawa; Keiji Matsuda; Munehiko Sugimoto; Katsuo Shitoto; Hisashi Kurosawa

2009-01-01

33

5B.1 Metallosis in Metal-on-Metal PPF Total Hip Arthroplasties  

Microsoft Academic Search

Metallosis in total hip arthroplasty (THA) is a not commonly reported complication. We followed 173 consecutive patients, who had received primary, single and non-cemented proximal press fit (PFF) THA with metal-on-metal bearings made of low carbon content in 1995. Follow-up results are available for a total of 161 (93.1%) patients. The mean age of the patients was 63.3 years (31

R. Legenstein; W. Huber; P. Boesch

34

Osteolysis with a cementless second generation metal-on-metal cup in total hip replacement  

Microsoft Academic Search

This study examined the long-term results of a metal-on-metal total hip replacement with a Metasul-lined cup. Twenty-nine\\u000a total hip arthroplasties were performed in 27 young patients (mean age 49 years). Twenty-two patients (23 hips) were available\\u000a for clinical and radiographic analysis after a mean duration of 99 months. Mean preoperative Harris hip score of 60 improved\\u000a to 93 at most

Ian Holloway; William L. Walter; Bernie Zicat; William K. Walter

2009-01-01

35

Cobalt and chromium ion release after large-diameter metal-on-metal total hip arthroplasty.  

PubMed

Seventy-five patients underwent unilateral metal-on-metal total hip arthroplasty using a large-diameter head. Serum levels of cobalt and chromium were determined. Significant increases in both cobalt and chromium were observed at 3 months (cobalt, 1.4 ?g/L; chromium, 1.4 ?g/L) compared with preoperative values (P < .001). At 1 year, the median cobalt and chromium levels were 2.3 and 2.1 ?g/L, respectively, and the levels had increased significantly compared with 3 months (P < .001). There were no significant differences between levels of either metal at 1 or 2 years (cobalt, 2.3 ?g/L; chromium, 1.6 ?g/L). Pseudotumor occurred in 2 hips. Patients with large-diameter metal-on-metal total hip arthroplasty had higher circulating metal ion levels at 3 months and 1 year, with no additional significant increases at 2 years. PMID:22325959

Hasegawa, Masahiro; Yoshida, Kakunoshin; Wakabayashi, Hiroki; Sudo, Akihiro

2012-06-01

36

Metal-on-metal versus metal-on-polyethylene bearings in total hip arthroplasty  

Microsoft Academic Search

This case-control study was performed to investigate the hypothesis that metal-on-metal (M-M) bearings reduce the risk of aseptic component loosening when compared with metal-on-polyethylene (M-PE) bearings. Cases were identified from a computerized joint database as patients who had received a primary total hip arthroplasty using an M-M or M-PE bearing and had documented revision or radiographic loosening of the stem

Douglas Naudie; Christopher P. Roeder; Javad Parvizi; Daniel J. Berry; Stefan Eggli; Andre Busato

2004-01-01

37

Quantification of self-polishing in vivo from explanted metal-on-metal total hip replacements  

Microsoft Academic Search

One of the claimed advantages of metal-on-metal total hip replacements is that they ‘self-polish’ in the body, however this assertion has not been supported by quantitative data. Two pairs of components, each consisting of a femoral head and acetabular cup, were obtained at revision surgery. They were subject to topographical analysis using a non-contacting profilometer. In the ‘worn’ regions a

Thomas J. Joyce; Harry Grigg; David J. Langton; Antoni V. F. Nargol

2011-01-01

38

Femoral Neck Fractures After Metal-on-Metal Total Hip Resurfacing  

Microsoft Academic Search

There has been a renewed interest in metal-on-metal resurfacing total hip arthroplasty. Recent studies have reported high success rates at short to midterm follow-up. Despite these excellent early outcomes, femoral neck fractures have been reported as a major complication after this procedure. The purpose of this study was to identify the incidence of this complication in a prospective cohort of

David R. Marker; Thorsten M. Seyler; Riyaz H. Jinnah; Ronald E. Delanois; Slif D. Ulrich; Michael A. Mont

2007-01-01

39

Delayed hypersensitivity reaction caused by metal-on-metal total disc replacement.  

PubMed

The authors report the case of a 53-year-old woman who underwent placement of a metal-on-metal total disc replacement (TDR) device for the treatment of discogenic back pain. The initial postoperative course was normal, but 2 months after surgery she started to complain of a recurrence of pain and she progressively developed cauda equina syndrome. Radiological and biological findings showed an inflammatory polyneuropathy associated with an epidural mass. A diagnosis of cell-mediated hypersensitivity reaction (Type IV) was made after patch testing showed positive reactions for 1% cobalt chloride and chromium. A decision was made to remove the TDR device and to perform a circumferential fusion. This report is intended to inform the reader that systemic metal release and hypersensitivity reaction are possible complications of metal-on-metal TDR. PMID:23829286

Zairi, Fahed; Remacle, Jean Michel; Allaoui, Mohamed; Assaker, Richard

2013-09-01

40

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

PubMed

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 ?g/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. PMID:20832379

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

2010-12-01

41

Pseudotumor with dominant B-lymphocyte infiltration after metal-on-metal total hip arthroplasty with a modular cup.  

PubMed

We report a case of a patient who underwent metal-on-metal total hip arthroplasty with a modular cup and developed a pseudotumor 5 years postoperatively. Immunohistochemistry showed dominant B-lymphocyte infiltration in the periprosthetic tissue. PMID:21723086

Hasegawa, Masahiro; Yoshida, Kakunoshin; Wakabayashi, Hiroki; Sudo, Akihiro

2012-03-01

42

Long-duration metal-on-metal total hip arthroplasties with low wear of the articulating surfaces  

Microsoft Academic Search

The 20-year performance of metal-on-metal hip articulations has not been reported. Five McKee—Farrar total hip prostheses and one Sivash prosthesis were obtained at revision surgery after a mean implantation time of 21.3 years. A radiographic, histologic, implant, and wear analysis was performed on these total hip implants with cobalt—chrome metal-on-metal articulations. All cases were associated with femoral component loosening, but

Thomas P. Schmalzried; Paul C. Peters; Brian T. Maurer; Charles R. Bragdon; William H. Harris

1996-01-01

43

Cementless Total Hip Arthroplasty With a Metal-on-Metal Bearing in Patients Younger Than 50 Years  

Microsoft Academic Search

Total hip arthroplasty (THA) longevity is the primary concern in young patients. Metal-on-metal articulations were reintroduced to reduce polyethylene particle-induced osteolysis and improve survivorship; to date, based on issued reports, this strategy appears to have been successful. In this study, the authors investigated metal-on-metal articulation survivorship and osteolysis incidence in young patients (19-50 years old at index operations) and retrospectively

Kyu-Tae Hwang; Young-Ho Kim; Yee-Suk Kim; Il-Yong Choi

2011-01-01

44

Long-term results of metasul metal-on-metal total hip arthroplasty.  

PubMed

We assessed 90 total hip arthroplasties (THAs) performed with the Metasul metal-on-metal hip system (Zimmer, Warsaw, Indiana); the patients were monitored for >10 years. The average Harris Hip Score of the patients was 40.5 points preoperatively and 85.8 points at final follow-up. No adverse reactions to the metal debris were observed in patients presenting with symptoms or phenomena such as unexplained pain, joint effusion, bursitis, or pseudotumor. Radiographically, the acetabular component fixation was stable in 86 hips, possibly unstable in 3 hips, and unstable in 1 hip. The unstable hip required revision of the acetabular component. The femoral component was bone-ingrown in 81 hips and stable-fibrous in 9 hips. Distal femoral cortical hypertrophy was seen in 34.4% of hips.Postoperatively, 6 hips dislocated, of which 2 developed recurrent dislocation and required revision of the acetabular component. Dissociation of the polyethylene liner occurred in 2 hips 6 and 12 years postoperatively, respectively, and required revision of the polyethylene liner and the articular head. The survival rate with the endpoint defined as revision surgery and radiologic loosening was 94.4% at mean follow-up (12.3 years). This study found that the Metasul metal-on-metal THA produces excellent long-term results. PMID:20704108

Saito, Shu; Ishii, Takao; Mori, Sei; Hosaka, Kunihiro; Ootaki, Munenori; Tokuhashi, Yasuaki

2010-08-01

45

Systemic metal exposure in large- and small-diameter metal-on-metal total hip replacements.  

PubMed

Large-diameter metal-metal total hip replacement (THR) offers the advantages of low wear and low dislocation risk. the aim of this investigation was to compare metal levels in large and small-diameter metal-metal hip replacements. Whole blood concentrations and daily output of cobalt and chromium in 28 patients with unilateral large diameter (42- to 54-mm) metal on metal hip replacements at 1-year follow-up were compared with levels in patients with 28-mm metal-on-metal THRs. Both bearings were made of high-carbon cobalt-chrome alloy. The larger bearing is as-cast and the smaller wrought alloy. High-resolution inductively coupled plasma mass spectrometry was used for analysis. The patients had either a cemented polished tapered stainless steel stem or a cementless porous ingrowth titanium alloy stem. Mean whole blood levels in the small- and large-diameter THRs are not significantly different at 1 year (cobalt, 1.7 vs 2.3 microg/L and chromium 1.7 vs 1.4 microg/L). Daily urinary output of cobalt and chromium was also in the same range and without a significant mean difference (cobalt 11.6 microg/24 h in large-diameter and 12.3 microg/24 h in small-diameter THRs and chromium 3.7 and 4.1 microg/24 h, respectively). PMID:19298017

Daniel, Joseph; Ziaee, Hena; Pradhan, Chandra; McMinn, Derek J W

2008-12-01

46

Friction in metal-on-metal total disc arthroplasty: effect of ball radius.  

PubMed

Total disc arthroplasty (TDA) can be used to replace a degenerated intervertebral disc in the spine. There are different designs of prosthetic discs, but one of the most common is a ball-and-socket combination. Contact between the bearing surfaces can result in high frictional torque, which can then result in wear and implant loosening. This study was designed to determine the effects of ball radius on friction. Generic models of metal-on-metal TDA were manufactured with ball radii of 10, 12, 14 and 16 mm, with a radial clearance of 0.015 mm. A simulator was used to test each sample in flexion-extension, lateral bending and axial rotation at frequencies of 0.25, 0.5, 0.75, 1, 1.25, 1.5, 1.75 and 2 Hz under loads of 50, 600, 1200 and 2000 N, in new born calf serum. Frictional torque was measured and Stribeck curves were plotted to illustrate the lubrication regime in each case. It was observed that implants with a smaller ball radius showed lower friction and showed boundary and mixed lubrication regimes, whereas implants with larger ball radius showed boundary lubrication only. This study suggests designing metal-on-metal TDAs with ball radius of 10 or 12 mm, in order to reduce wear and implant loosening. PMID:22177670

Moghadas, Parshia; Mahomed, Aziza; Hukins, David W L; Shepherd, Duncan E T

2012-02-01

47

Pseudotumor in large-diameter metal-on-metal total hip articulation.  

PubMed

Large-diameter metal-on-metal hip arthroplasties have incited renewed interest because of the advantages of decreased wear and increased stability. These new designs have not had significant long-term or midterm performance results, and we are reporting the case of pseudotumor in a patient with a painful metal-on-metal hip arthroplasty. PMID:20663635

Shahrdar, Cambize

2011-06-01

48

Five- to ten-year outcomes for modular metal-on-metal total hip arthroplasty.  

PubMed

In recent years, metal-on-metal (MOM) arthroplasty has come under fire with reported adverse outcomes of metal hypersensitivity, adverse local tissue reaction (ALTR), and the carcinogenicity concern from systemic metal ions. We present a retrospective analysis of 354 primary total hip arthroplasties from 2 independent centers. Revision data, predicted survival and Harris Hip Scores (HHS) are reported. Nine hips (2.5%) underwent component revision, and 9 year predicted survival was 95.8%. One revision had elevated metal ions but no histological evidence of ALTR. Average HHS at a minimum 5 year follow up (range 5-10 years) improved significantly from 52 pre-operatively to 93 post-operatively. While a 2.5% revision rate and improved clinical outcomes are reported in this study, longer term follow-up is warranted to monitor for late complications. PMID:23643031

Bernasek, Thomas L; Polikandriotis, John A; Levering, Melissa F; Dalury, David F; Fisher, David A; Adler, Michael J

2013-08-01

49

A comparative assessment of small-head metal-on-metal and ceramic-on-polyethylene total hip replacement.  

PubMed

Large-head metal-on-metal (MoM) total hip replacements (THR) have given rise to concern. Comparative studies of small-head MoM THRs over a longer follow-up period are lacking. Our objective was to compare the incidence of complications such as infection, dislocation, revision, adverse local tissue reactions, mortality and radiological and clinical outcomes in small-head (28 mm) MoM and ceramic-on-polyethylene (CoP) THRs up to 12 years post-operatively. A prospective cohort study included 3341 THRs in 2714 patients. The mean age was 69.1 years (range 24 to 98) and 1848 (55.3%) were performed in women, with a mean follow-up of 115 months (18 to 201). There were 883 MoM and 2458 CoP bearings. Crude incidence rates (cases/1000 person-years) were: infection 1.3 vs 0.8; dislocation 3.3 vs 3.1 and all-cause revision 4.3 vs 2.2, respectively. There was a significantly higher revision rate after ten years (adjusted hazard ratio 9.4; 95% CI 2.6 to 33.6) in the MoM group, and ten of 26 patients presented with an adverse local tissue reaction at revision. No differences in mortality, osteolysis or clinical outcome were seen. In conclusion, we found similar results for small-head MoM and CoP bearings up to ten years post-operatively, but after ten years MoM THRs had a higher risk of all-cause revision. Furthermore, the presence of an adverse response to metal debris seen in the small-head MOM group at revision is a cause for concern. Cite this article: Bone Joint J 2014; 96-B:868-75. PMID:24986938

Lübbeke, A; Gonzalez, A; Garavaglia, G; Roussos, C; Bonvin, A; Stern, R; Peter, R; Hoffmeyer, P

2014-07-01

50

The Prevalence of Groin Pain After Metal-on-Metal Total Hip Arthroplasty and Total Hip Resurfacing  

Microsoft Academic Search

Background  Groin pain after total hip arthroplasty (THA) or total hip resurfacing arthroplasty can be troubling for patients and surgeons.\\u000a Potential sources of pain include infection, loosening, metal hypersensitivity, or impingement of bony structures or the iliopsoas\\u000a tendon.\\u000a \\u000a \\u000a \\u000a \\u000a Questions\\/purposes  We compared the rate of groin pain after THA or hip resurfacing using metal-on-metal to those of other bearing surfaces.\\u000a \\u000a \\u000a \\u000a Methods  We identified 347

Robert B. Bartelt; Brandon J. Yuan; Robert T. Trousdale; Rafael J. Sierra

2010-01-01

51

2008 John Charnley Award: Metal Ion Levels After Metal-on-Metal Total Hip Arthroplasty: A Randomized Trial  

Microsoft Academic Search

Metal-on-metal bearing total hip arthroplasty is performed more commonly than in the past. There may be manufacturing differences\\u000a such as clearance, roughness, metallurgy, and head size that affect performance. In a prospective, randomized trial, we compared\\u000a 2-year postoperative ion levels for a 28-mm metal-on-polyethylene bearing with 28-mm and 36-mm metal-on-metal bearings. We\\u000a measured serum, erythrocyte, and urine ion levels. We

C. Anderson Engh Jr; Steven J. MacDonald; Supatra Sritulanondha; Abigail Thompson; Douglas Naudie; Charles A. Engh

2009-01-01

52

Large diameter metal on metal articulations. Comparison of total hip arthroplasty and hip resurfacing arthroplasty.  

PubMed

The use of large diameter metal bearing total hip arthroplasty (THA) and hip resurfacing arthroplasty (HRA) increased in popularity in the last decade. More recent literature has highlighted the effect of head size in patient outcomes. Data was obtained from the Australian Orthopaedic Association National Joint Replacement Registry (AOA-NJRR) to evaluate the Birmingham (MoM) bearing surface when used with THA and HRA. There is no difference in the overall rate of revision between the THA and HRA but head size has a significant effect on revision rate. The data show that small diameter metal bearings in HRA (below 50mm) have a higher rate of revision than large diameter metal bearings in HRA (equal to and above 50mm) (P<.001). Conversely the large diameter metal bearings in THA have a higher rate of revision than the small diameter metal bearings in THA (P=.027). The revision rate for large diameter HRA compared to small diameter THA is not significantly different P=.670. We recommend caution when choosing either a large diameter (?50mm) metal on metal THA or small diameter (<50mm) HRA. PMID:23140992

Jack, Christopher M; Walter, William L; Shimmin, Andrew J; Cashman, Kara; de Steiger, Richard N

2013-04-01

53

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

PubMed

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 < 0.05) suggesting a local clinical effect of the elevated serum 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. PMID:23677963

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

2013-10-01

54

CONCOMITANT INFECTION AND LOCAL METAL REACTION IN PATIENTS UNDERGOING REVISION OF METAL ON METAL TOTAL HIP ARTHROPLASTY  

PubMed Central

Total hip arthroplasty (THA) with conventional polyethylene bearings is traditionally the standard operative treatment for endstage arthritis of the hip. This design has excellent survivorship in most populations, with a low occurrence of infection and other associated complications. Due to concern over increased wear in younger, more active populations, other bearing surfaces have been evaluated, particularly metal-on-metal with wear rates theorized to be lower than conventional THA. Unique to metal-on-metal THA, however, is the possibility of local soft tissue reactions that can mimic infection, making proper diagnosis and treatment difficult. We present a case series of nine hips in eight patients undergoing revision of metal-on-metal THA for local soft tissue reactions, three of which were also found to be concomitantly infected. The laboratory and hip aspirate data described show significant overlap between the infected and non-infected cases. Care must be taken when evaluating patients with failed metal-on-metal THA as there may be an increased incidence of co-infection in this group of patients.

Judd, Kyle T; Noiseux, Nicolas

2011-01-01

55

Metal-on-metal total hip arthroplasty - five- to 11-year follow-up.  

PubMed

Metal-on-metal (MoM) total hip arthroplasty (THA) has been introduced in an attempt to reduce the wear rate and the consequent osteolysis around implants. The aim of this study was to present the intermediate to long-term clinical and radiological outcomes and to investigate the metal ion levels in the blood of patients who had undergone primary uncemented MoM THA in our institution. Between July 1997 and November 2003, 166 patients (193 hips), with a mean age of 50 years (range, 18-65 years), underwent primary MoM THA. Clinical data, radiographs, and blood samples were obtained at regular follow-up visits. Cobalt (Co), chromium (Cr), and molybdenum (Mo) ions were measured by inductively coupled plasma-mass spectrometry (ICP-MS) from the patient's whole blood. All patients were prospectively followed for a minimum of 5 years (mean, 7 years; range, 5-11 years). The mean Harris hip score (HHS) and the University of California at Los Angeles (UCLA) activity score at the latest follow-up was 88 ± 11 and 7 ± 1.8 points, respectively. Thirteen hips have been revised. Ten acetabular components had early failure, due to factory manufacturing problems. All other implants have been found stable, with no signs of aseptic loosening. The probability of survival at 11 years, if the hips that were revised due to manufacturing problems were excluded, was 98.4%. The Co and Cr metal ion levels, after increasing significantly during the first 4 to 5 years post-surgery, remained stable, with a tendency to decrease thereafter, but not significantly. During the same follow-up period, Mo ion levels remained stable. In this 5-to-11 year follow-up study of MoM THA patients, excellent survivorship, with low complications rates, was found. Results of longer follow-up studies are necessary to clarify the possible long-term effects of metal ion release. PMID:22035490

Nikolaou, Vassilios S; Petit, Alain; Debiparshad, Kevin; Huk, Olga L; Zukor, David J; Antoniou, John

2011-01-01

56

Gender is a Significant Factor for Failure of Metal-on-Metal Total Hip Arthroplasty  

Microsoft Academic Search

Metal-on-metal (MoM) articulations offers low wear, larger head size, and increased stability. Reports of early failure are troubling and include failure of ingrowth and metal articulation problems such as metallosis, hypersensitivity, pseudotumor, and unexplained pain. This study investigates the survivorship of modern MoM articulations by gender. We reviewed 1589 primary MoM THA in 1363 patients, with minimum 2-year follow-up for

Michael J. Latteier; Keith R. Berend; Adolph V. Lombardi; Andrew F. Ajluni; Brian E. Seng; Joanne B. Adams

2011-01-01

57

An American experience with metal-on-metal total hip arthroplasties  

Microsoft Academic Search

This study reviews the clinical performance of 161 hip arthroplasties (154 patients) with the Metasul metal-on-metal articulation and an uncemented modular acetabular component. Between 1995 and 2002 clinical evaluation and radiographic follow-up of patients included Harris hip scores, patient self-assessment, and radiographs. Twelve operative site complications (7.5%) included 6 revision operations, (3.7%) and 3 other complications (1.9%) not needing reoperation.

William T. Long; Lawrence D. Dorr; Vlad Gendelman

2004-01-01

58

Metallosis, psoas abscess and infected hip prosthesis in a patient with bilateral metal on metal total hip replacement  

PubMed Central

Metal on metal hip (MoM) resurfacing / replacement has recently been one of the most discussed topics in orthopaedics. Significant revision rates and complications are associated with MoM. We report a patient presenting with infection of a total hip prosthesis in conjunction with a psoas abscess in which the presentation is complicated by radiological evidence of suspected metallic debris in the lower limb tissues and elevated chromium and cobalt levels, suggestive of metallosis secondary to MoM.

Rymaruk, S; Razak, A; McGivney, R

2012-01-01

59

Disappointing Short-Term Results With the DePuy ASR XL Metal-on-Metal Total Hip Arthroplasty  

Microsoft Academic Search

Outcomes of ultralarge-diameter femoral heads used in metal-on-metal (MOM) total hip arthroplasty (THA) are relatively unknown. This study reports on early failures of the ASR XL (Depuy, Warsaw, Ind) and assesses whether a correlation with cup positioning exists. A retrospective review of 70 consecutive MOM THAs with ultralarge-diameter femoral head and monoblock acetabular component was conducted. Minimum follow-up was 24

Nicholas M. Bernthal; Paul C. Celestre; Alexandra I. Stavrakis; John C. Ludington; Daniel A. Oakes

60

Metallosis, psoas abscess and infected hip prosthesis in a patient with bilateral metal on metal total hip replacement.  

PubMed

Metal on metal hip (MoM) resurfacing / replacement has recently been one of the most discussed topics in orthopaedics. Significant revision rates and complications are associated with MoM. We report a patient presenting with infection of a total hip prosthesis in conjunction with a psoas abscess in which the presentation is complicated by radiological evidence of suspected metallic debris in the lower limb tissues and elevated chromium and cobalt levels, suggestive of metallosis secondary to MoM. PMID:24960139

Rymaruk, S; Razak, A; McGivney, R

2012-01-01

61

Cutaneous manifestation of metallosis in a metal-on-metal total hip arthroplasty after acetabular liner dissociation.  

PubMed

In this case report, we describe a cutaneous manifestation of extensive metallosis in a patient 4 months post-metal-on-metal total hip arthroplasty with a Pinnacle cup with dissociation of the liner from the shell and resultant stripe burnishing of the shell and notch wear of the femoral neck. Dissociation of a metal liner has not been previously reported with this implant. Cutaneous metallosis has only been reported once in the literature. Clinicians should heighten their suspicion for metallosis secondary to hardware failure when encountering patients with skin discoloration in the setting of a painful and poorly functioning hip arthroplasty. In patients with failure of a metal-on-metal prosthesis with a modular metal liner in the acetabular component, liner dissociation must be considered. PMID:22397858

Sporer, Scott M; Chalmers, Peter N

2012-09-01

62

Modern metal-on-metal hip implants.  

PubMed

This Technology Overview was prepared using systematic review methodology and summarizes the findings of studies published as of July 15, 2011, on modern metal-on-metal hip implants. Analyses conducted on outcomes by two joint registries indicate that patients who receive metal-on-metal total hip arthroplasty (THA) and hip resurfacing are at greater risk for revision than are patients who receive THA using a different bearing surface combination. Data from these registries also indicate that larger femoral head components have higher revision rates and risk of revision and that older age is associated with increased revision risks of large-head metal-on-metal THA. Several studies noted a correlation between suboptimal hip implant positioning and higher wear rates, local metal debris release, and consequent local tissue reactions to metal debris. In addition, several studies reported elevated serum metal ion concentrations in patients with metal-on-metal hip articulations, although the clinical significance of these elevated ion concentrations remains unknown. PMID:22661570

Bozic, Kevin J; Browne, James; Dangles, Chris J; Manner, Paul A; Yates, Adolph J; Weber, Kristy L; Boyer, Kevin M; Zemaitis, Paul; Woznica, Anne; Turkelson, Charles M; Wies, Janet L

2012-06-01

63

A Systematic Review of Modern Metal-on-Metal Total Hip Resurfacing vs Standard Total Hip Arthroplasty in Active Young Patients  

Microsoft Academic Search

This systematic review compared 2 treatments for hip disease in active young patients: modern metal-on-metal total hip resurfacing and standard total hip arthroplasty. We conducted a literature search to identify relevant randomized and clinical controlled trials and included 968 patients from 4 trials in our analysis. Our results indicated increased rates of revision, femoral neck fractures, and component loosening among

Yong Jiang; Kaifang Zhang; Jun Die; Zhibing Shi; Haien Zhao; Kunzheng Wang

2011-01-01

64

Metal ion levels in patients with a lumbar metal-on-metal total disc replacement: should we be concerned?  

PubMed

The purpose of this study was to evaluate whether concerns about the release of metal ions in metal-on-metal total hip replacements (THR) should be extended to patients with metal-bearing total disc replacements (TDR). Cobalt and chromium levels in whole blood and serum were measured in ten patients with a single-level TDR after a mean follow-up of 34.5 months (13 to 61) using inductively-coupled plasma mass spectrometry. These metal ion levels were compared with pre-operative control levels in 81 patients and with metal ion levels 12 months after metal-on-metal THR (n = 21) and resurfacing hip replacement (n = 36). Flexion-extension radiographs were used to verify movement of the TDR. Cobalt levels in whole blood and serum were significantly lower in the TDR group than in either the THR (p = 0.007) or the resurfacing group (p < 0.001). Both chromium levels were also significantly lower after TDR versus hip resurfacing (p < 0.001), whereas compared with THR this difference was only significant for serum levels (p = 0.008). All metal ion levels in the THR and resurfacing groups were significantly higher than in the control group (p < 0.001). In the TDR group only cobalt in whole blood appeared to be significantly higher (p < 0.001). The median range of movement of the TDR was 15.5° (10° to 22°). These results suggest that there is minimal cause for concern about high metal ion concentrations after TDR, as the levels appear to be only moderately elevated. However, spinal surgeons using a metal-on-metal TDR should still be aware of concerns expressed in the hip replacement literature about toxicity from elevated metal ion levels, and inform their patients appropriately. PMID:21705569

Bisseling, P; Zeilstra, D J; Hol, A M; van Susante, J L C

2011-07-01

65

Long-Term Clinical, Radiological and Histopathological Follow-Up of a Well-Fixed McKee-Farrar Metal-on-Metal Total Hip Arthroplasty  

Microsoft Academic Search

Metal-on-metal is one potential bearing option for total hip arthroplasty (THA). Proponents of the bearing have suggested that if the tribology is optimal, volumetric wear may occur at levels at least one order of magnitude lower than metal-on-polyethylene bearings. We present a unique postmortem case of a well fixed, metal-on-metal, McKee-Farrar total hip arthroplasty implanted 30 years previously that was

Michael T. Clarke; Clare Darrah; Todd Stewart; Eileen Ingham; John Fisher; John F. Nolan

2005-01-01

66

Gender is a significant factor for failure of metal-on-metal total hip arthroplasty.  

PubMed

Metal-on-metal (MoM) articulations offers low wear, larger head size, and increased stability. Reports of early failure are troubling and include failure of ingrowth and metal articulation problems such as metallosis, hypersensitivity, pseudotumor, and unexplained pain. This study investigates the survivorship of modern MoM articulations by gender. We reviewed 1589 primary MoM THA in 1363 patients, with minimum 2-year follow-up for 1212 hips. Follow-up averaged 60 months. There were 643 female patients and 719 male patients. The incidence of cup revision was significantly higher in women than in men (8.2% vs 2.7%; P = .0000), as was incidence of aseptic loosening (4.3% vs 1.1%; P = .0006), and failure for metal-bearing complications (2.2% vs 0.6%; P = .0126). There appear to be gender factors influencing the success of MoM THA, which may include hormonal, anatomic, or functional differences. PMID:21641761

Latteier, Michael J; Berend, Keith R; Lombardi, Adolph V; Ajluni, Andrew F; Seng, Brian E; Adams, Joanne B

2011-09-01

67

Histologic, serologic, and tribologic findings in failed metal-on-metal total hip arthroplasty: AAOS exhibit selection.  

PubMed

Despite multiple changes in second-generation metal-on-metal hip implants, greater-than-expected revision rates have led to alarm. We hypothesized that the finding of intraoperative metallosis would be associated with a high metal load on histologic analysis and that both would be associated with increased wear, greater serum metal ion levels, and predictable biologic responses in the histologic sections. We evaluated the implant positioning, serum ion levels, intraoperative findings of metallosis, wear characteristics of retrieved implants (tribology), histology, and outcomes in a series of eighteen large-diameter metal-on-metal total hip arthroplasties. The arthroplasties were divided into two groups on the basis of the intraoperative finding of metallosis and into two groups on the basis of the metal load score. Intraoperative metallosis was not associated with a high metal load score (p = 0.15). The finding of intraoperative metallosis was associated with greater serum metal ion levels, greater wear rates, and greater complication rates. Aseptic lymphocyte-dominated vasculitis-associated lesion (ALVAL) scores were similar between the metallosis and non-metallosis groups (p = 0.49) as well as between the high and low-metal-load groups (p = 0.56). PMID:24196475

Pelt, Christopher E; Erickson, Jill; Clarke, Ian; Donaldson, Thomas; Layfield, Lester; Peters, Christopher L

2013-11-01

68

Understanding the differences between the wear of metal-on-metal and ceramic-on-metal total hip replacements.  

PubMed

Hip simulator studies have been carried out extensively to understand and test artificial hip implants in vitro as an efficient alternative to obtaining long-term results in vivo. Recent studies have shown that a ceramic-on-metal material combination lowers the wear by up to 100 times in comparison with a typical metal-on-metal design. The reason for this reduction remains unclear and for this reason this study has undertaken simple tribometer tests to understand the fundamental material loss mechanisms in two material combinations: metal-on-metal and ceramic-on-ceramic. A simple-configuration reciprocating pin-on-plate wear study was performed under open-circuit potential (OCP) and with applied cathodic protection (CP) in a serum solution using two tribological couples: firstly, cobalt-chromium (Co-Cr) pins against Co-Cr plates; secondly, Co-Cr pins against alumina (Al2O3) plates. The pin and plate surfaces prior to and after testing were examined by profilometry and scanning electron microscopy. The results showed a marked reduction in wear when CP was applied, indicating that total material degradation under the OCP condition was attributed to corrosion processes. The substitution of the Co-Cr pin with an Al2O3 plate also resulted in a dramatic reduction in wear, probably due to the reduction in the corrosion-wear interactions between the tribological pair. PMID:18491698

Figueiredo-Pina, C G; Yan, Y; Neville, A; Fisher, J

2008-04-01

69

Retrieval analysis of 240 metal-on-metal hip components, comparing modular total hip replacement with hip resurfacing.  

PubMed

This study compared component wear rates and pre-revision blood metal ions levels in two groups of failed metal-on-metal hip arthroplasties: hip resurfacing and modular total hip replacement (THR). There was no significant difference in the median rate of linear wear between the groups for both acetabular (p = 0.4633) and femoral (p = 0.0872) components. There was also no significant difference in the median linear wear rates when failed hip resurfacing and modular THR hips of the same type (ASR and Birmingham hip resurfacing (BHR)) were compared. Unlike other studies of well-functioning hips, there was no significant difference in pre-revision blood metal ion levels between hip resurfacing and modular THR. Edge loading was common in both groups, but more common in the resurfacing group (67%) than in the modular group (57%). However, this was not significant (p = 0.3479). We attribute this difference to retention of the neck in resurfacing of the hip, leading to impingement-type edge loading. This was supported by visual evidence of impingement on the femur. These findings show that failed metal-on-metal hip resurfacing and modular THRs have similar component wear rates and are both associated with raised pre-revision blood levels of metal ions. PMID:21357950

Matthies, A; Underwood, R; Cann, P; Ilo, K; Nawaz, Z; Skinner, J; Hart, A J

2011-03-01

70

Early failure of the Ultima metal-on-metal total hip replacement in the presence of normal plain radiographs.  

PubMed

Metal-on-metal total hip replacement has been targeted at younger patients with anticipated long-term survival, but the effect of the production of metal ions is a concern because of their possible toxicity to cells. We have reviewed the results of the use of the Ultima hybrid metal-on-metal total hip replacement, with a cemented polished tapered femoral component with a 28 mm diameter and a cobalt-chrome (CoCr) modular head, articulating with a 28 mm CoCr acetabular bearing surface secured in a titanium alloy uncemented shell. Between 1997 and 2004, 545 patients with 652 affected hips underwent replacement using this system. Up to 31 January 2008, 90 (13.8%) hips in 82 patients had been revised. Pain was the sole reason for revision in 44 hips (48.9%) of which 35 had normal plain radiographs. Peri-prosthetic fractures occurred in 17 hips (18.9%) with early dislocation in three (3.3%) and late dislocation in 16 (17.8%). Infection was found in nine hips (10.0%). At operation, a range of changes was noted including cavities containing cloudy fluid under pressure, necrotic soft tissues with avulsed tendons and denuded osteonecrotic upper femora. Corrosion was frequently observed on the retrieved cemented part of the femoral component. Typically, the peri-operative findings confirmed those found on pre-operative metal artefact reduction sequence MRI and histological examination showed severe necrosis. Metal artefact reduction sequence MRI proved to be useful when investigating these patients with pain in the absence of adverse plain radiological features. PMID:21037343

Donell, S T; Darrah, C; Nolan, J F; Wimhurst, J; Toms, A; Barker, T H W; Case, C P; Tucker, J K

2010-11-01

71

Recurrent intrapelvic cyst complicating metal-on-metal cemented total hip arthroplasty  

Microsoft Academic Search

Spontaneous intrapelvic masses causing vascular compression raise the suspicion of a neoplasm or infection. We present a\\u000a patient who developed a recurrent intrapelvic cyst 14 years after a McKee-Farrar total hip arthroplasty which presented as\\u000a acute onset of lower limb swelling, threatening the vascularity of the limb. This cyst recurred three times, and the patient\\u000a finally needed revision total hip

S. Madan; Richard L. Jowett; Mark I. Goodwin

2000-01-01

72

Cup-neck impingement due to the malposition of the implant as a possible mechanism for metallosis in metal-on-metal total hip arthroplasty.  

PubMed

The metal-on-metal bearing total hip prosthesis is expected to reduce the risk of debris-related osteolysis. However, several reports demonstrated that the socket-stem impingement in the metal-on-metal prosthesis due to the implant malposition results in titanium wear debris and secondary metallosis. In this article, we presented a case of massive metallosis due to metal-on-metal impingement. A 60-year woman had severe hip pain due to fracture of the greater trochanter. We planned a revision of the metal-on-metal inlay. Intraoperatively, the trochanteric bursa and joint space were found to be stained black. Black stained granulation tissue was observed between the femoral stem and the great trochanter. Intraoperatively, notching was noticed on both the posteroinferior aspect of the neck of the femoral component and the anterior aspect of the metal liner and polyethylene core. The notch corresponded to the position of impingement between the socket and the femoral neck during the maximum extension of the hip. To clarify the mechanism of cup-neck impingement, the alignment of the prosthesis and pelvic tilt were evaluated. The cup was placed in too much anteverted position. In addition, increased posterior tilt of pelvis in the standing position made the anteversion of the acetabular cup more significant, which enhanced the cup-neck impingement during the gait. Careful attention is necessary for implant alignment and pelvic tilt especially in metal-on-metal-bearing total hip arthroplasty. PMID:19292272

Onda, Kazunori; Nagoya, Satoshi; Kaya, Mitsunori; Yamashita, Toshihiko

2008-04-01

73

Mortality rates at 10 years after metal-on-metal hip resurfacing compared with total hip replacement in England: retrospective cohort analysis of hospital episode statistics  

PubMed Central

Objectives To compare 10 year mortality rates among patients undergoing metal-on-metal hip resurfacing and total hip replacement in England. Design Retrospective cohort study. Setting English hospital episode statistics database linked to mortality records from the Office for National Statistics. Population All adults who underwent primary elective hip replacement for osteoarthritis from April 1999 to March 2012. The exposure of interest was prosthesis type: cemented total hip replacement, uncemented total hip replacement, and metal-on-metal hip resurfacing. Confounding variables included age, sex, Charlson comorbidity index, rurality, area deprivation, surgical volume, and year of operation. Main outcome measures All cause mortality. Propensity score matching was used to minimise confounding by indication. Kaplan-Meier plots estimated the probability of survival up to 10 years after surgery. Multilevel Cox regression modelling, stratified on matched sets, described the association between prosthesis type and time to death, accounting for variation across hospital trusts. Results 7437 patients undergoing metal-on-metal hip resurfacing were matched to 22?311 undergoing cemented total hip replacement; 8101 patients undergoing metal-on-metal hip resurfacing were matched to 24?303 undergoing uncemented total hip replacement. 10 year rates of cumulative mortality were 271 (3.6%) for metal-on-metal hip resurfacing versus 1363 (6.1%) for cemented total hip replacement, and 239 (3.0%) for metal-on-metal hip resurfacing versus 999 (4.1%) for uncemented total hip replacement. Patients undergoing metal-on-metal hip resurfacing had an increased survival probability (hazard ratio 0.51 (95% confidence interval 0.45 to 0.59) for cemented hip replacement; 0.55 (0.47 to 0.65) for uncemented hip replacement). There was no evidence for an interaction with age or sex. Conclusions Patients with hip osteoarthritis undergoing metal-on-metal hip resurfacing have reduced mortality in the long term compared with those undergoing cemented or uncemented total hip replacement. This difference persisted after extensive adjustment for confounding factors available in our data. The study results can be applied to matched populations, which exclude patients who are very old and have had complex total hip replacements. Although residual confounding is possible, the observed effect size is large. These findings require validation in external cohorts and randomised clinical trials.

2013-01-01

74

Controversies in Large Metal-on-Metal Cementless Total Hip Arthroplasty  

Microsoft Academic Search

Over the last several years, many orthopaedic surgeons have embraced so-called alternative bearing surfaces in total hip arthroplasty, largely on the basis of the hypothesis that a reduction in the volumetric wear rates afforded by these improved articulating couples will reduce the prevalence of osteolysis and aseptic loosening, which in turn will improve implant survivorship. We conducted the study on

P. Botez; C. I. Stoica; P. D. Sirbu; R. Asaftei; C. Grierosu

2010-01-01

75

Long-term clinical, radiological and histopathological follow-up of a well-fixed Mckee-Farrar metal-on-metal total hip arthroplasty.  

PubMed

Metal-on-metal is one potential bearing option for total hip arthroplasty (THA). Proponents of the bearing have suggested that if the tribology is optimal, volumetric wear may occur at levels at least one order of magnitude lower than metal-on-polyethylene bearings. We present a unique postmortem case of a well fixed, metal-on-metal, McKee-Farrar total hip arthroplasty implanted 30 years previously that was clinically asymptomatic in life. Clinical and radiological examination is supplemented by tribological examination of the bearing and histopathological examination of the cement-bone interface. PMID:16124974

Clarke, Michael T; Darrah, Clare; Stewart, Todd; Ingham, Eileen; Fisher, John; Nolan, John F

2005-06-01

76

[Metal on metal bearing surfaces in total hip arthroplasty: a survey of material incidents].  

PubMed

This study is dedicated to the problems met with metal-metal bearing prostheses. We have analysed the results of the reports sent to the AFSSAPS relating incidents described with this interface. Only 11 incidents were reported during the last 4 years by surgeons from different centers in France. At a mean follow-up of 7 years, we collected 2614 total hip arthroplasties with metal-metal bearings and among them only 5 cases of unusual osteolysis and 10 cases of impingement. The bibliographic analysis did not show any severe specific complication due to the release of Cobalt or Chromium ions. The increased levels of Co an Cr in the patients' blood is now a well established notion (with more than 10 years follow up) and no special carcinogenetic effect has been correlated with the metal-metal bearings. Small diameter cemented cups can provide complications with high rates of acetabular loosening and metallosis; the same is true for some cementless cups also with loosening and a high revision rate. Among 143 hip prosthesis with a cemented polyethylene cup, at a mean follow-up of 42 months there were 22% of evolutive radiolucencies around the cups concerning all three De Lee and Charnley zones. Furthermore there was a statistically significant difference between small and large diameter cups (loosening of cups less than 46 mm in diameter). The same problem has been described for some cementless cups with loosening at the metal-bone interface due to a failure of osteointegration at the implant surface. However no failures were observed with an hydroxyapatite coating on the same cup. An other matter of concern is the skirted metal head: this design is responsible for a high rate of impingement and of prosthetic revision (2.3% among 642 THA). In these cases the increase of Cobalt serum levels was well correlated with the failure of the metal-metal interface. Large diameter heads decrease significantly the risks of dislocation. This is correlated with the increase in size. The release of ions in the blood was not affected by the large diameter compared to the regular size. So this overview confirms that if we respect some basic rules for the indications there are no specific complications related to the use of metal-metal bearings. In prospective studies the results of ceramic-ceramic and metal-metal bearings are similar but we must keep on observing prospectively the patients as for the release of Co and Cr. PMID:17534213

Passuti, N; Terver, S

2007-05-01

77

Serum ion levels after ceramic-on-ceramic and metal-on-metal total hip arthroplasty: 8-year minimum follow-up.  

PubMed

Alternative bearing surfaces for total hip arthroplasty, such as metal-on-metal and ceramic-on-ceramic, offer the potential to reduce mechanical wear and osteolysis. In the short and medium term, the second generation of metal-on-metal bearings demonstrated high systemic metal ion levels, whereas ceramic-on-ceramic bearings showed the lowest ones. We aimed to verify whether the long-term ion release in metal-on-metal subjects was still relevant at a median 10-year follow-up, and whether a fretting process at the modular junctions occurred in ceramic-on-ceramic patients and induced an ion dissemination. Serum levels were measured in 32 patients with alumina-on-alumina implants (group A), in 16 subjects with metal-on-metal implants (group B), and in 47 healthy subjects (group C). Group B results were compared with medium-term findings. Cobalt and chromium levels were significantly higher in metal-on-metal implants than in ceramic-on-ceramic ones and controls. Nevertheless, ion levels showed a tendency to decrease in comparison with medium-term content. In ceramic-on-ceramic implants, ion values were not significantly different from controls. Both in groups A and B, aluminum and titanium release were not significantly different from controls. In conclusion, negligible serum metal ion content was revealed in ceramic-on-ceramic patients. On the contrary, due to the higher ion release, metal-on-metal coupling must be prudently considered, especially in young patients, in order to obtain definitive conclusions. PMID:18634038

Savarino, Lucia; Padovani, Giovanni; Ferretti, Massimo; Greco, Michelina; Cenni, Elisabetta; Perrone, Giorgio; Greco, Francesco; Baldini, Nicola; Giunti, Armando

2008-12-01

78

Cystic Lesion of the Groin due to Metallosis: A Rare Long-Term Complication of Metal-on-Metal Total Hip Arthroplasty  

Microsoft Academic Search

We present 2 patients with swelling of the groin after metal-on-metal total hip arthroplasty without radiological signs of component loosening. Magnetic resonance imaging in both patients showed a round intrapelvic lesion ventral to the femoral head. During surgery, we found cystic structures filled with fluid and necrotic masses. After resection of the cyst, the metal head and insert were replaced

Florian W. Gruber; Andreas Böck; Siegfried Trattnig; Felix Lintner; Peter Ritschl

2007-01-01

79

Quantitative analysis of the wear and wear debris from low and high carbon content cobalt chrome alloys used in metal on metal total hip replacements  

Microsoft Academic Search

The biological reactions to polyethylene wear debris have been shown to result in osteolysis and loosening of total hip arthroplasties. This has led to renewed interest in the use of metal on metal bearings in hip prostheses. This study employed uniaxial and biaxial multistation pin on plate reciprocators to assess how the carbon content of the cobalt chrome alloy and

J. L. Tipper; P. J. Firkins; E. Ingham; J. Fisher; M. H. Stone; R. Farrar

1999-01-01

80

Similar range of motion and function after resurfacing large-head or standard total hip arthroplasty  

PubMed Central

Background and purpose Large–size hip articulations may improve range of motion (ROM) and function compared to a 28–mm THA, and the low risk of dislocation allows the patients more activity postoperatively. On the other hand, the greater extent of surgery for resurfacing hip arthroplasty (RHA) could impair rehabilitation. We investigated the effect of head size and surgical procedure on postoperative rehabilitation in a randomized clinical trial (RCT). Methods We followed randomized groups of RHAs, large–head THAs and standard THAs at 2 months, 6 months, 1 and 2 years postoperatively, recording clinical rehabilitation parameters. Results Large articulations increased the mean total range of motion by 13° during the first 6 postoperative months. The increase was not statistically significant and was transient. The 2–year total ROM (SD) for RHA, standard THA, and large–head THA was 221° (35), 232° (36), and 225° (30) respectively, but the differences were not statistically significant. The 3 groups were similar regarding Harris hip score, UCLA activity score, step rate, and sick leave. Interpretation Head size had no influence on range of motion. The lack of restriction allowed for large articulations did not improve the clinical and patient–perceived outcomes. The more extensive surgical procedure of RHA did not impair the rehabilitation. This project is registered at ClinicalTrials.gov under # NCT01113762.

2013-01-01

81

Immunologic Adverse Reaction Associated with Low-carbide Metal-on-metal Bearings in Total Hip Arthroplasty  

Microsoft Academic Search

Background  An increased incidence of periprosthetic osteolysis, resulting in loss of biologic fixation, has been reported in contemporary\\u000a THAs with low-carbide metal-on-metal compared with metal-on-polyethylene couple bearings. Although a hypersensitivity reaction\\u000a attributable to Co and Cr debris is reportedly a potential cause for failure of THAs with high-carbide bearings, there are\\u000a no evidence-based data for this reaction in low-carbide metal-on-metal bearings,

Panagiotis Aroukatos; Maria Repanti; Thomas Repantis; Vassiliki Bravou; Panagiotis Korovessis

2010-01-01

82

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

PubMed

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 detrimental effects on bone. It is unknown whether serum metal ion levels affect bone density clinically. We compared cementless large femoral head (mean 48 mm) metal-on-metal total hip arthroplasties (M2a-Magnum, Biomet) to cementless 28 mm metal-on-polyethylene total hip arthroplasties (Mallory-Head, Biomet) in a randomised clinical trial. We evaluated periprosthetic acetabular bone density and serum metal ion levels at 1 year postoperatively. Acetabular bone density was analyzed with dual energy x-ray absorptiometry in four horizontal regions of interest in 70 patients. After one year, acetabular bone density decreased (-3.5% to -7.8%) in three of four regions of interest in metal-on-polyethylene patients, but was retained in metal-on-metal patients. Bone density preservation was most pronounced superior to the metal-on-metal cup (+1% versus -3.7%). Serum cobalt, chromium and titanium ion levels were not related to bone density, nor to acetabular inclination or femoral head size. Oxford and Harris hip scores were similar in both groups. Contrary to our hypothesis, acetabular bone density was retained with metal-on-metal total hip arthroplasty, compared to metal-on-polyethylene arthroplasty. Bone preservation was most pronounced in the area superior to the cup. This could be a benefit during future revision surgery. PMID:24186673

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

2014-01-01

83

Metal-on-metal CoCrMo McKee-Farrar total hip arthroplasty: characteristics from a long-term follow-up study  

Microsoft Academic Search

A total of 38 cemented metal-on-metal CoCrMo McKee-Farrar total hip arthroplasties (THAs) were clinically and radiographically evaluated over a long-term follow-up. No osteolysis and no granuloma were found more than 20 years after the operation. The main radiological findings were bone erosion and migration of the acetabular component, seen in 17 hips (44.7%). The direction of the migration correlated with

F. Higuchi; A. Inoue; M. Semlitsch

1997-01-01

84

Total hip arthroplasty using large-diameter metal-on-metal articulation in patients with neuromuscular weakness.  

PubMed

The purpose of this prospective study was to evaluate the clinical and functional outcomes of THA using large-diameter metal-on-metal articulation in patients with neuromuscular weakness. Nineteen consecutive patients (19 hips) with neuromuscular weakness and displaced femoral neck fractures were enrolled. Functional improvement and recovery, radiological evaluation of THA and surgical morbidity were assessed. Mean Harris hip and WOMAC scores at final follow-up were 81.0 and 42.9, respectively. At final follow-up, no dislocation, metal hypersensitivity, or osteolysis was observed and no patient required revision of THA. The findings of this study indicate that the functional results of THA using large-diameter metal-on-metal articulation in patients with neuromuscular weakness can produce satisfactory outcomes with early functional recovery and a low dislocation rate. PMID:24051238

Park, Kyung-Soon; Seon, Jong-Keun; Lee, Keun-Bae; Yoon, Taek-Rim

2014-04-01

85

Foreign body response around total prosthetic metal-on-metal replacements of the temporomandibular joint in the UK.  

PubMed

Replacements for the temporomandibular joint were developed in the early 1960s. Problems with various prostheses, notably the Kent VK1, led to detailed analysis of their risks and complications. In 1999 one type of prosthesis (the Christensen) was converted from an acrylic condyle on cobalt-chromium fossa to metal-on-metal cobalt-chrome condyle and fossa. This has been popular for the last 15 years in the UK, but since it was converted to the metal-on-metal variant there have been several cases of foreign body giant-cell reactions to the prosthesis. Of the 9 cases seen (out of 106 placed), 4 were found retrospectively to be sensitive to one of the metal components of the prosthesis; the others have not been tested to date. Other potential causes of this reaction are point contact, micromovement, or a lymphocyte-mediated response to the prosthesis. PMID:18242801

Sidebottom, A J; Speculand, B; Hensher, R

2008-06-01

86

Second generation of metal-on-metal cemented total hip replacements: 12 years of clinical and biological follow-up  

Microsoft Academic Search

The second generation of metal-on-metal prostheses appeared at the end of the 1980’s as a serious alternative to metal on\\u000a polyethylene bearing couples. Short-term clinical results were promising; however certain questions remain concerning clinical,\\u000a radiological and biological aspects. Release of chromium and cobalt from the bearing couple is one of these aspects. The aim\\u000a of this study is to analyse

J.-Y. Lazennec; P. Boyer; J. Poupon; M.-A. Rousseau; F. Laude; S. El Balkhi; Y. Catonne; G. Saillant

2007-01-01

87

Foreign body response around total prosthetic metal-on-metal replacements of the temporomandibular joint in the UK  

Microsoft Academic Search

Replacements for the temporomandibular joint were developed in the early 1960s. Problems with various prostheses, notably the Kent VK1, led to detailed analysis of their risks and complications. In 1999 one type of prosthesis (the Christensen) was converted from an acrylic condyle on cobalt-chromium fossa to metal-on-metal cobalt-chrome condyle and fossa. This has been popular for the last 15 years

A. J. Sidebottom; B. Speculand; R. Hensher

2008-01-01

88

Leg edema due to a mass in the pelvis after a large-diameter metal-on-metal total hip arthroplasty.  

PubMed

We report the case of a patient with leg edema after large-diameter metal-on-metal total hip arthroplasty. At 1 year and 2 months after primary left large-diameter metal-on-metal total hip arthroplasty, the patient complained of left leg edema. At first, we suspected deep venous thrombosis. However, deep venous thrombosis was not detected by venous ultrasonographic examination. Computed tomography imaging revealed a mass in front of the iliac fossa. The mass compressed the left iliac artery and vein. We therefore believed that this lesion was the cause of the leg edema and performed resection of the mass. The resected mass consisted of necrotic tissue infiltrating inflammation cells, so it was diagnosed as pseudotumor. Unilateral leg edema disappeared gradually after the resection. PMID:22704029

Kawakita, Kohei; Shibanuma, Nao; Tei, Katsumasa; Nishiyama, Takayuki; Kuroda, Ryosuke; Kurosaka, Masahiro

2013-01-01

89

Effect of 3D physiological loading and motion on elastohydrodynamic lubrication of metal-on-metal total hip replacements.  

PubMed

An elastohydrodynamic lubrication (EHL) simulation of a metal-on-metal (MOM) total hip implant was presented, considering both steady state and transient physiological loading and motion gait cycle in all three directions. The governing equations were solved numerically by the multi-grid method and fast Fourier transform in spherical coordinates, and full numerical solutions were presented included the pressure and film thickness distribution. Despite small variations in the magnitude of 3D resultant load, the horizontal anterior-posterior (AP) and medial-lateral (ML) load components were found to translate the contact area substantially in the corresponding direction and consequently to result in significant squeeze-film actions. For a cup positioned anatomically at 45 degrees , the variation of the resultant load was shown unlikely to cause the edge contact. The contact area was found within the cup dimensions of 70-130 degrees and 90-150 degrees in the AP and ML direction respectively even under the largest translations. Under walking conditions, the horizontal load components had a significant impact on the lubrication film due to the squeeze-film effect. The time-dependent film thickness was increased by the horizontal translation and decreased during the reverse of this translation caused by the multi-direction of the AP load during walking. The minimum film thickness of 12-20 nm was found at 0.4s and around the location at (95, 125) degrees. During the whole walking cycle both the average and centre film thickness were found obviously increased to a range of 40-65 nm, compared with the range of 25-55 nm under one load (vertical) and one motion (flexion-extension) condition, which suggested the lubrication in the current MOM hip implant was improved under 3D physiological loading and motion. This study suggested the lubrication performance especially the film thickness distribution should vary greatly under different operating conditions and the time and location that potential wear may occur was very sensitive to specific loading and motion conditions. This may provide some explanation to the large variations in wear from hip simulators and clinical studies, and also stress the importance of using more realistic loading and motion conditions in the tribological study of MOM hip prostheses. PMID:19269879

Gao, Leiming; Wang, Fengcai; Yang, Peiran; Jin, Zhongmin

2009-07-01

90

Long-term results of a contemporary metal-on-metal total hip arthroplasty: a 10-year follow-up study.  

PubMed

The goal of the study was to evaluate the long-term results of a metal-on-metal articulation. We evaluated the results and histologic findings in patients who had undergone revision. One hundred total hip arthroplasties with a Lubrimet metal-on-metal articulation (Smith and Nephew, Rotkreuz, Switzerland) were implanted in 99 consecutive unselected patients in 1995 and 1996, and the results were prospectively analyzed up to a mean of 126 months postoperatively. Periprosthetic tissues of all 6 hips that had undergone revision because of aseptic loosening, mechanical failure, or periprosthetic fracture showed metallosis and extensive lymphocytic and plasma cell infiltration around the metal debris. With removal of the component because of aseptic loosening as the end point, survivorship was 98% for the stem and 96% for the cup. PMID:19596544

Neumann, Daniel R P; Thaler, Christoph; Hitzl, Wolfgang; Huber, Monika; Hofstädter, Thomas; Dorn, Ulrich

2010-08-01

91

Metal-on-metal or metal-on-polyethylene for total hip arthroplasty: a meta-analysis of prospective randomized studies  

Microsoft Academic Search

Background  There has been recent concern regarding the increased use of metal-on-metal total hip arthroplasty (MOM-THA) as an alternative\\u000a to contemporary metal-on-polyethylene total hip arthroplasty (MOP-THA), and the choice remains controversial. We performed\\u000a a meta-analysis to evaluate and compare metal ion concentrations, complications, reoperation rates, clinical outcomes and\\u000a radiographic outcomes of MOM-THA and MOP-THA.\\u000a \\u000a \\u000a \\u000a \\u000a Methods  We performed a systematic review of English

Xinhua Qu; Xiaolu Huang; Kerong Dai

92

Cushion bearings versus large diameter head metal-on-metal bearings in total hip arthroplasty: a short-term metal ion study  

Microsoft Academic Search

Introduction  Metal-on-metal total hip arthroplasty (MOM THA) has the advantage of replicating the femoral head size, but the postoperative\\u000a elevation of serum metal ion levels is a cause for concern. Metal-on-polycarbonate-urethane is a new cushion bearing featuring\\u000a a large diameter metal head coupled with a polycarbonate-urethane liner.\\u000a \\u000a \\u000a \\u000a \\u000a Aim  The aim of this study was to assess and compare serum cobalt (Co) and

Antonio Moroni; Emanuele Nocco; Martha Hoque; Elena Diremigio; Dario Buffoli; Francesco Cantù; Simona Catalani; Pietro Apostoli

93

Evaluation of the wear properties of a metal-on-metal total joint replacement system and in vitro macrophage response to resultant wear particles  

NASA Astrophysics Data System (ADS)

The wear of the polyethylene in total joint prostheses has been a source of morbidity and early device failure which has been extensively reported in the last ten to twelve years. While research continues to attempt to reduce the wear of polyethylene joint bearing surfaces by modifications in polymer processing, there is a renewed interest in the use of metal-on-metal bearing couples for hip replacement devices. This study investigated the in vitro wear resistance of two cobalt/chromium/molybdenum alloys, which differed primarily in the carbon content, as potential alloys for use in such a metal-on-metal hip bearing couple. The results showed that the alloy with the higher (0.25%) carbon content was more wear resistant and this alloy was chosen for testing in a hip simulator system which modeled the loads and motions which might be exerted on a clinically implanted hip replacement. Comparison of the results of metal-on-polyethylene specimens to metal-on-metal specimens showed that the volumetric wear of the metal-on-polyethylene bearing couple over 5,000,000 cycles was 110--180 times as great as that for the metal bearing couple. Polyethylene and metal particles retrieved from either pin-on-disk testing lubricant or hip simulator testing lubricant were cleaned and examined for consistency with the particles reported by other laboratories for particles from periprosthetic tissues and found to be similar. The particles were then added to macrophage (J774a) cell cultures and the release of Prostaglandin E2, Interleukin-6, and Tumor Necrosis Factor alpha measured for each experiment in response to the particles. The cell mediators released by the cells was found to correlate with the dosage of particles and the chemical identity of the particles. Most of the cellular response to the polyethylene particles seemed to be as a result of phagocytosis of the particles while most of the response to metal particles seemed to be related to cytotoxicity of the particles. Based upon the results of this study, metal-on-metal hip prostheses prepared from the high carbon cobalt/chromium alloy (CCM+) that was investigated seem to hold sufficient promise to justify human clinical trials.

St. John, Kenneth Raymond

94

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  

PubMed Central

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 short, no high frequency of adverse reactions to this prosthesis is expected.

Sturup, Jens; Dahl, Line B; Jensen, Karl-Erik; Larsen, Anne-Birgitte; Gebuhr, Peter

2012-01-01

95

Failure of Larger-Diameter Metal-on-Metal Total Hip Arthroplasty Resulting from Anterior Iliopsoas Impingement  

Microsoft Academic Search

Anterior iliopsoas impingement is a recognized cause of persistent groin pain after total hip arthroplasty. We report 3 patients with failed total hip arthroplasties resulting from anterior iliopsoas and capsular impingement secondary to a metal femoral ball with a diameter larger than the native femoral head. All patients had the same implant design. Resolution of symptoms occurred in all patients

James A. Browne; David J. Polga; Rafael J. Sierra; Robert T. Trousdale; Miguel E. Cabanela

2011-01-01

96

Metal ion levels decrease after revision for metallosis arising from large-diameter metal-on-metal hip arthroplasty.  

PubMed

Concerns have been renewed regarding the possible long-term effects of elevated circulating levels of cobalt and chromium as a direct result of implantation of large femoral head diameter metal-on-metal bearings. In order to establish whether metal ion levels remain persistently elevated, we compared metal ion levels before and after revision surgery in patients with large head diameter (greater than 38 mm) metal-on-metal total hip arthroplasty or hip resurfacing arthroplasty. At greater than one year post removal of a large-diameter metal-on-metal hip implant for the indication of symptomatic metallosis, metal ion levels were found to fall to almost normal levels. PMID:22308623

Ebreo, Darren; Khan, Abdul; El-Meligy, Mohammed; Armstrong, Catherine; Peter, Viju

2011-12-01

97

Lessons learned from loosening of the McKee-Farrar metal-on-metal total hip replacement  

Microsoft Academic Search

Clinical and radiographic data for 15 McKee-Farrar hip replacements that had failed because of aseptic loosening (4 stem loosening, 9 cup loosening, and 2 loosening of both components) between 0.6 and 21 years (average, 8.3 years) were compared with 15 hips in which the McKee-Farrar total hip replacement has survived between 21 and 26 years. Hips that loosened were biomechanically

Christopher A. Zahiri; Thomas P. Schmalzried; Edward Ebramzadeh; Edward S. Szuszczewicz; David Salib; Carrie Kim; Harlan C. Amstutz

1999-01-01

98

The Long-Term Wear of Retrieved McKee-Farrar Metal-on-Metal Total Hip Prostheses  

Microsoft Academic Search

Twenty-four cobalt-chrome alloy McKee-Farrar matching acetabular and femoral components were retrieved at revision total hip arthroplasty. The average time in situ was 16 years. Wear and loss of sphericity was very low. Polishing wear (type 1), fine abrasive (type 2), multidirectional dull abrasive (type 3), and unidirectional dull abrasive wear (type 4) of the articulating surfaces were identified. The mean

Donald W. Howie; Richard W. McCalden; Namal S. Nawana; Kerry Costi; Mark J. Pearcy; Chinnia Subramanian

2005-01-01

99

Three to six-year results with the ultima metal-on-metal hip articulation for primary total hip arthroplasty  

Microsoft Academic Search

One hundred seventy-one primary total hip arthroplasties were evaluated in a prospective, randomized study. Ninety-five involved a metal-backed cup with an all-metal liner and 76 involved a metal-backed polyethylene cup that was used as the control. All were implanted with an S-ROM cementless femoral component with a 28 mm head. The mean follow-up period was 3.7 years (range, 3.0–5.7). The

Michael Jacobs; Robert Gorab; David Mattingly; Lorence Trick; Carleton Southworth

2004-01-01

100

Necrotic pseudotumor caused by a metal-on-metal total hip prosthesis: imaging characteristics on 18 F-FDG PET\\/CT and correlative imaging  

Microsoft Academic Search

Necrotic pseudotumor is a complication of metal-on-metal arthroplasty that has been reported with increasing frequency in\\u000a the last 5 years. It is believed to be the result of a hypersensitivity reaction to metal ions such as nickel, cobalt, or\\u000a chromium that are released in large quantities from these prostheses. The imaging appearance of a necrotic pseudotumor caused\\u000a by a metal-on-metal prosthesis,

William Makis; Christopher Rush; Gad Abikhzer

2011-01-01

101

Serial magnetic resonance imaging of metal-on-metal total hip replacements. Follow-up of a cohort of 28 mm Ultima TPS THRs.  

PubMed

Metal artefact reduction (MAR) MRI is now widely considered to be the standard for imaging metal-on-metal (MoM) hip implants. The Medicines and Healthcare Products Regulatory Agency (MHRA) has recommended cross-sectional imaging for all patients with symptomatic MoM bearings. This paper describes the natural history of MoM disease in a 28 mm MoM total hip replacement (THR) using MAR MRI. Inclusion criteria were patients with MoM THRs who had not been revised and had at least two serial MAR MRI scans. All examinations were reported by an experienced observer and classified as A (normal), B (infection) or C1-C3 (mild, moderate, severe MoM-related abnormalities). Between 2002 and 2011 a total of 239 MRIs were performed on 80 patients (two to four scans per THR); 63 initial MRIs (61%) were normal. On subsequent MRIs, six initially normal scans (9.5%) showed progression to a disease state; 15 (15%) of 103 THRs with sequential scans demonstrated worsening disease on subsequent imaging. Most patients with a MoM THR who do not undergo early revision have normal MRI scans. Late progression (from normal to abnormal, or from mild to more severe MoM disease) is not common and takes place over several years. PMID:23908416

Ebreo, D; Bell, P J; Arshad, H; Donell, S T; Toms, A; Nolan, J F

2013-08-01

102

Does Choice of Head Size and Neck Geometry Affect Stem Migration in Modular Large-Diameter Metal-on-Metal Total Hip Arthroplasty? A Preliminary Analysis  

PubMed Central

Due to their theoretical advantages, hip systems combining modular necks and large diameter femoral heads have gradually gained popularity. However, among others, concerns regarding changes in the load transfer patterns were raised. Recent stress analyses have indeed shown that the use of modular necks and big femoral heads causes significant changes in the strain distribution along the femur. Our original hypothesis was that these changes may affect early distal migration of a modular stem. We examined the effect of head diameter and neck geometry on migration at two years of follow-up in a case series of 116 patients (125 hips), who have undergone primary Metal-on-Metal total hip arthroplasty with the modular grit-blasted Profemur®E stem combined with large-diameter heads (>36 mm). We found that choice of neck geometry and head diameter has no effect on stem migration. A multivariate regression analysis including the potential confounding variables of the body mass index, bone quality, canal fill and stem positioning revealed only a negative correlation between subsidence and canal fill in midstem area. Statistical analysis, despite its limitations, did not confirm our hypothesis that choice of neck geometry and/or head diameter affects early distal migration of a modular stem. However, the importance of correct stem sizing was revealed.

Georgiou, CS; Evangelou, KG; Theodorou, EG; Provatidis, CG; Megas, PD

2012-01-01

103

Local tissue reaction and necrosis-induced femoral nerve palsy in a patient with a metal-on-metal total hip arthroplasty: a case report.  

PubMed

This case report describes a 54-year-old Hispanic male who developed femoral nerve palsy approximately 1 year after metal-on-metal total hip arthroplasty (MOM THA). Cobalt and chromium levels were 4.8 ppb and undetectable, respectively. MRI demonstrated a well-encapsulated pseudotumor that communicated with the anterior portion of the right hip, and EMG showed neuropraxic femoral nerve injury. As a result, the patient experienced motor and sensory loss in the femoral and proximal saphenous nerve distributions. Surgical revision to ceramic-on-poly THA with debridement and decompression of the pseudotumor improved the patient's neurological status. Similar acute local tissue reactions have been described but the serum levels of cobalt and chrome associated with these reactions have been variable. Wear particles and products produced from corrosion at the head taper junction from MOM THA can potentially lead to cellular dysfunction with subsequent pseudotumer formation, but these reactions and fluid collections have also been found. In this patient, serum cobalt levels were elevated, while serum chromium levels remained undetectable. The purpose of this case report is to describe one patient's response and to review the recent literature regarding potential complications of MOM THA. PMID:24941401

Wodowski, Andrew J; Rider, Carson M; Mihalko, William M

2014-01-01

104

The Latest Lessons Learned from Retrieval Analyses of Ultra-High Molecular Weight Polyethylene, Metal-on-Metal, and Alternative Bearing Total Disc Replacements  

PubMed Central

Knowledge regarding the in vivo performance and periposthetic tissue response of cervical and lumbar total disc replacements (TDRs) continues to expand. This review addresses the following four main questions: 1) What are the latest lessons learned from polyethylene in large joints and how are they relevant to current TDRs? 2) What are the latest lessons learned regarding adverse local tissue reactions from metal-on-metal, CoCr bearings in large joints and how are they relevant to current TDRs? 3) What advancements have been made in understanding the in vivo performance of alternative biomaterials, such as stainless steel and polycarbonate urethane, for TDRs in the past five years? 4) How has retrieval analysis of all these various artificial disc bearing technologies advanced the state of the art in preclinical testing of TDRs? The study of explanted artificial discs and their associated tissues can help inform bearing selection as well as the design of future generations of disc arthroplasty. Analyzing retrieved artificial discs is also essential for validating preclinical test methods.

Kurtz, Steven M.; Toth, Jeffrey M.; Siskey, Ryan; Ciccarelli, Lauren; MacDonald, Dan; Isaza, Jorge; Lanman, Todd; Punt, Ilona; Steinbeck, Marla; Goffin, Jan; van Ooij, Andre

2012-01-01

105

In vitro analysis of the wear, wear debris and biological activity of surface-engineered coatings for use in metal-on-metal total hip replacements.  

PubMed

Extremely low wear rates have been reported for metal-on-metal total hip replacements, but concerns remain about the effects of metal ion release, dissolution rates and toxicity. Surface-engineered coatings have the potential to improve wear resistance and reduce the biological activity of the wear debris produced. The aim of this study was to examine the wear and wear debris generation from surface-engineered coatings: titanium nitride (TiN), chromium nitride (CrN) and chromium carbon nitride (CrCN) applied to a cobalt-chrome alloy (CoCr) substrate. The coatings were articulated against themselves in a simple geometry model. The wear particles generated were characterized and the cytotoxic effect on U937 macrophages and L929 fibroblasts assessed. The CrN and CrCN coatings showed a decrease in wear compared to the CoCr bearings and produced small (less than 40 nm in length) wear particles. The wear particles released from the surface engineered bearings also showed a decreased cytotoxic effect on cells compared to the CoCr alloy debris. The reduced wear volumes coupled with the reduced cytotoxicity per unit volume of wear indicate the potential for the clinical application of this technology. PMID:12807156

Williams, S; Tipper, J L; Ingham, E; Stone, M H; Fisher, J

2003-01-01

106

Fracture of a dual-modular femoral component at the stem-sleeve junction in a metal-on-metal total hip arthroplasty.  

PubMed

Innovations in the design of dual-modular femoral components have afforded surgeons several intraoperative advantages during both primary and revision total hip arthroplasty (THA). Although use of these implants has become more popular, the long-term outcomes and potential complications of introducing a second modular junction are still to be determined. In addition, concerns about corrosion potentiation at modular junctions in metal-on-metal (MOM) THA have arisen in recent studies. In this article, we present a unique case of fracture at the modular junction of the stem and modular sleeve of a dual-modular femoral component implanted with a MOM articulation. The proposed mechanisms of failure, including crevice and fretting corrosion as well as the potential effect of metal debris generated by MOM articulations, are reviewed. This case report is the first to describe component fracture at the stem-sleeve junction of this modern-generation dual-modular femoral component. Surgeons who encounter a painful dual-modular femoral stem must entertain this mode of failure and consider junctional failure as a potential diagnosis for such a patient, particularly in the setting of a MOM articulation. PMID:24660185

Frank, Rachel M; Biswas, Debdut; Levine, Brett R

2014-03-01

107

Metal-on-metal hip arthroplasty: going, going, gone... - affirms.  

PubMed

Metal-on-metal hip arthroplasty gained significant favor in the first decade of the millennium. However, the past several years have seen increasing reports of failure, pseudotumor and other adverse reactions. This study presents the results of a single center's 15-year experience with metal-on-metal total hip arthroplasty as strong evidence that metal-on-metal is going, going, gone. PMID:23118387

Berend, K R; Morris, M J; Adams, J B; Lombardi, A V

2012-11-01

108

A retrospective comparative study of mortality and causes of death among patients with metal-on-metal and metal-on-polyethylene total hip prostheses in primary osteoarthritis after a long-term follow-up  

Microsoft Academic Search

BACKGROUND: All patients with total hip arthroplasty (THA), especially those with metal-on-metal (MM) THA, are exposed to metallic particles and ions, which may cause total or site-specific mortality. We analyzed the causes of total and site-specific mortality among a cohort of patients with MM and with metal-on-polyethylene (MP) THA after a long follow-up time. METHODS: Standardized mortality ratios (SMR) of

Tuomo Visuri; Håkan Borg; Pekka Pulkkinen; Pekka Paavolainen; Eero Pukkala

2010-01-01

109

Massive wear of an incompatible metal-on-metal articulation in total hip arthroplasty 1 1 No benefits or funds were received in support of this study  

Microsoft Academic Search

We report on a case of massive wear because of an incompatible metal-on-metal combination. In a 62-year-old man, a cobalt-chromium (CoCr) inlay and a stainless steel head were paired by accident. Because of persistent pain, revision surgery was performed 7 months later. Histologic analysis of the surrounding tissue revealed massive metallosis. The wear volume was increased by a factor of

Johannes B Keel; Markus S Kuster

2004-01-01

110

Metal-on-Metal Hip Resurfacing  

Microsoft Academic Search

Modern metal-on-metal resurfacing has recently gained popularity as an alternative to standard stemmed total hip arthroplasty. This study analyzed, from a literature review, the purported advantages and disadvantages of resurfacing with a comparison to standard hip arthroplasty. Advantages may include bone conservation on the femoral side with possible lower dislocation rates, more range-of-motion, more normal gait pattern, increased activity levels,

Mario J. Quesada; David R. Marker; Michael A. Mont

2008-01-01

111

Necrotic pseudotumor caused by a metal-on-metal total hip prosthesis: imaging characteristics on (18)F-FDG PET/CT and correlative imaging.  

PubMed

Necrotic pseudotumor is a complication of metal-on-metal arthroplasty that has been reported with increasing frequency in the last 5 years. It is believed to be the result of a hypersensitivity reaction to metal ions such as nickel, cobalt, or chromium that are released in large quantities from these prostheses. The imaging appearance of a necrotic pseudotumor caused by a metal-on-metal prosthesis, on (18)F-FDG PET/CT or (99m)Tc-MDP bone scan has not been previously described in the literature. Our case demonstrates that a necrotic pseudotumor can be detected incidentally in oncologic patients referred for an (18)F-FDG PET/CT or a (99m)Tc-MDP bone scan, and recognizing this process is vital in preventing further tissue necrosis and patient morbidity, as the offending prosthesis must be promptly removed. The imaging characteristics of a necrotic pseudotumor on PET/CT and bone scan may also mimic a malignant process such as a necrotic sarcoma, and can represent a potential pitfall leading to a false positive diagnosis in an oncologic patient. PMID:21318272

Makis, William; Rush, Christopher; Abikhzer, Gad

2011-06-01

112

Metal Ion Hypersensitivity in Metal-on-Metal Hip Arthroplasty  

Microsoft Academic Search

Total hip arthroplasty with use of metal-on-metal bearings has been reintroduced as an alternative to metal-on-polyethylene\\u000a bearings because of theoretical advantages such as reduced wear and a lower prevalence of osteolysis. However, we have observed\\u000a early osteolysis in nine patients (ten hips) out of 165 patients (169 hips) who had been managed with total hip replacements\\u000a using a contemporary metal-on-metal

Y.-S. Park; Y.-W. Moon; S.-J. Lim

113

Metal-on-metal bearing surfaces.  

PubMed

Metal-on-metal bearing couples remain a popular option in total hip arthroplasty and are the only currently available option for surface replacement arthroplasty. In general, the intermediate-term clinical performance of metal-on-metal bearings has been favorable. There are, however, lingering concerns about the biologic consequences of metal release from these bearings in terms of both local tissue effects, including delayed-type hypersensitivity reactions in a subset of patients, and potential systemic effects as a consequence of chronic elevations in serum cobalt and chromium content. Advances in the understanding of the operant wear mechanisms in these bearings provide strategies for reducing the burden of metal released into the periprosthetic milieu, which in turn will mitigate the concerns about the biologic response to the metal debris. Continued surveillance of patients with these bearings is warranted to determine whether metal-on-metal bearing couples provide a long-term survivorship advantage over other bearing couple options and to evaluate whether chronic elevations in the body burden of cobalt and chromium is well tolerated over the long term. PMID:19202120

Jacobs, Joshua J; Urban, Robert M; Hallab, Nadim J; Skipor, Anastasia K; Fischer, Alfons; Wimmer, Markus A

2009-02-01

114

Dislocation of Large Diameter Metal-On-Metal Bearings  

Microsoft Academic Search

We report 3 patients who underwent total hip arthroplasty (THA) using large diameter metal-on-metal bearing. These patients initially presented with pain but went on to develop dislocation of the THA while awaiting investigations. Any pain following metal-on-metal bearing THA should be taken seriously and should trigger investigations to identify a metal reaction. If left untreated, these reactions can cause progressive

Bipin Theruvil; Nijil Vasukutty; Nick Hancock; David Higgs; Douglas G. Dunlop; Jeremy M. Latham

2011-01-01

115

Elevated Serum Cobalt With Metal-on-metal Articulating Surfaces  

Microsoft Academic Search

We determined serum cobalt levels in 55 patients by atomic absorption spectrophotometry before and after implantation of uncemented total hip arthroplasties. In a randomised, prospective trial 27 wrought Co-28Cr-6Mo-0.2C metal-on-metal articulations were compared with 28 ceramic-on-polyethylene hips which did not contain cobalt. Other sources of iatrogenic cobalt loading were excluded. The metal-on-metal group produced detectable serum cobalt levels (median 1.1

Wolfram Brodner; Peter Bitzan; Vanee Meisinger; Alexandra Kaider; Florian Gottsauner-Wolf; R. Kotz

1997-01-01

116

Strong association between smoking and the risk of revision in a cohort study of patients with metal-on-metal total hip arthroplasty.  

PubMed

Thus far the ability to predict who will develop early failure following the insertion of a metal-on-metal (MoM) bearing has been very limited. Our objective was to assess the effect of smoking on failure rates in patients with MoM bearing, compared with patients with ceramic-on-polyethylene (CoP) bearing. From a prospective hospital-based registry we included all primary THAs operated upon between 1/2001 and 12/2011 with MoM or CoP bearings of the same cup design and head size (28?mm). We compared revision rates through 10/2013 classified by smoking status and type of bearing. We included 1,964 patients (median age 71, 57% women), 663 with MoM and 1,301 with CoP bearing. Mean follow-up was 6.9 years (range 1.8-12.8). Revisions were required for 56 THAs. In patients with MoM bearing the adjusted incidence rate of revision among ever-smokers was four times greater than among never-smokers (95% CI 1.4-10.9). Among those with CoP bearing, the rate ratio was only 1.3 (95% CI 0.6-2.5). We found a strong association between smoking and increased failure of MoM THAs. In contrast, the association was weak for patients with CoP bearing. Smoking might be a trigger or an effect amplifier for adverse reactions to metal debris from MoM bearings. PMID:24615914

Lübbeke, Anne; Rothman, Kenneth J; Garavaglia, Guido; Barea, Christophe; Christofilopoulos, Panayiotis; Stern, Richard; Hoffmeyer, Pierre

2014-06-01

117

Effect of femoral head size on the wear of metal on metal bearings in total hip replacements under adverse edge-loading conditions  

PubMed Central

Abstract Metal-on-metal (MoM) bearings have shown low-wear rates under standard hip simulator conditions; however, retrieval studies have shown large variations in wear rates and mechanisms. High-wear in vivo has caused catastrophic complications and has been associated with steep cup-inclination angle (rotational malpositioning). However, increasing the cup-inclination angle in vitro has not replicated the increases in wear to the same extent as those observed in retrievals. Clinically relevant wear rates, patterns, and particles were observed in vitro for ceramic-on-ceramic bearings when microseparation (translational malpositioning) conditions were introduced into the gait cycle. In the present study, 28 and 36-mm MoM bearings were investigated under adverse conditions. Increasing the cup angle from 45° to 65° resulted in a significant increase in the wear rate of the 28 mm bearings. However, for the 36 mm bearings, head-rim contact did not occur under the steep cup-angle condition, and the wear rate did not increase. The introduction of microseparation to the gait cycle significantly increased the wear rate of the MoM bearings. Cup angle and head size did not influence the wear rate under microseparation conditions. This study indicated that high-in vivo wear rates were associated with edge loading due to rotational malpositioning such as high-cup-inclination angle and translational malpositioning that could occur due to several surgical factors. Translational malpositioning had a more dominant effect on the wear rate. Preclinical simulation testing should be undertaken with translational and rotational malpositioning conditions as well as standard walking cycle conditions defined by the ISO standard. © 2012 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2013.

Al-Hajjar, Mazen; Fisher, John; Williams, Sophie; Tipper, Joanne L; Jennings, Louise M

2013-01-01

118

[Update on metal-on-metal hip joints].  

PubMed

Increasing data are available describing risk factors for the development of local and systemic adverse events following operations using metal-on-metal (MoM) hip implants. The prevalence and clinical relevance of metal-associated problems are, however, still under debate. They can be influenced by type and position of implant as well as patient-specific factors. Patients with small MoM heads (maximum diameter 32 mm) and subgroups of resurfacing arthroplasty can achieve good long-term survival. The use of large head MoM implants (diameters greater than 36 mm), however, is currently not advised due to the unsatisfactory results. PMID:23632650

Günther, K-P; Lützner, J; Hannemann, F; Schmitt, J; Kirschner, S; Goronzy, J; Stiehler, M; Lohmann, C; Hartmann, A

2013-05-01

119

Squeaking in Metal-on-Metal Hip Resurfacing Arthroplasties  

Microsoft Academic Search

Background  While most reports of audible squeaking in total hip arthroplasty (THA) have focused on ceramic bearings, squeaking can occur\\u000a in metal-on-metal bearings and may be an important clinical complication to consider during patient followup.\\u000a \\u000a \\u000a \\u000a \\u000a Questions\\/purposes  We retrospectively identified 10 patients with squeaking metal-on-metal hip resurfacings.\\u000a \\u000a \\u000a \\u000a Methods  This study reports acetabular inclination angles and patient satisfaction, and describes two patients with squeaking resurfacings:

Christina Esposito; William L. Walter; Pat Campbell; Anne Roques

2010-01-01

120

A retrospective comparative study of mortality and causes of death among patients with metal-on-metal and metal-on-polyethylene total hip prostheses in primary osteoarthritis after a long-term follow-up  

PubMed Central

Background All patients with total hip arthroplasty (THA), especially those with metal-on-metal (MM) THA, are exposed to metallic particles and ions, which may cause total or site-specific mortality. We analyzed the causes of total and site-specific mortality among a cohort of patients with MM and with metal-on-polyethylene (MP) THA after a long follow-up time. Methods Standardized mortality ratios (SMR) of total and site-specific causes of death were calculated for 579 patients with MM (McKee-Farrar) and 1585 patients with MP (Brunswik, Lubinus) THA for primary osteoarthritis. Results Mean follow-up time was 17.9 years for patients with MM and 16.7 years for patients with MP. Overall SMR was 0.95 for the MM cohort and 0.90 for the MP cohort, as compared to the normal population. Both cohorts showed significantly decreased mortality for the first decade postoperatively, equal mortality over the next 10 years, and significantly increased mortality after 20 years. Patients with MM THA had higher cancer mortality (SMR 1.01) than those with MP THA (SMR 0.66) during the first 20 years postoperatively, but not thereafter. Conclusion Both MM and MP prostheses are safe based on total and site-specific mortality of recipients during the first 20 postoperative years in comparison with the general population.

2010-01-01

121

The minimal invasive direct anterior approach in combination with large heads in total hip arthroplasty - is dislocation still a major issue? a case control study  

PubMed Central

Background There have been increasing numbers of publications in recent years on minimally invasive surgery (MIS) for total hip arthroplasty (THA), reporting results with the use of different head sizes, tribologic and functional outcomes. This study presents the results and early complication rates after THA using the direct anterior approach (DAA) in combination with head sizes???36 mm. Methods A total of 113 patients with THA were included in the study. The Harris Hip Score (HHS) was determined, a radiographic evaluation was carried out, and complications were recorded. The minimum follow-up period was 2 years (means 35?±?7 months). Results The HHS improved from 43.6 (± 12) to 88.2 (± 14; P?large heads is associated with good to very good functional results in the majority of cases. The complication rates are not increased. The rate of dislocation mainly as an complication of the first two years can be markedly reduced in particular.

2014-01-01

122

Metal-on-metal hip resurfacing: a critical review  

Microsoft Academic Search

In this article, a concise review of the current literature on metal-on-metal hip resurfacing (MoMHR) is given. In contrast\\u000a to conventional total hip arthroplasty, older age, female sex and small femoral head sizes predispose to failure. Neck fracture\\u000a and metal wear-related complications account for the most frequent reasons for re-operations. Although the long-term consequences\\u000a of metal ion release remain unknown,

Gavin J. Macpherson; Steffen J. Breusch

2011-01-01

123

Silent soft tissue pathology is common with a modern metal-on-metal hip arthroplasty  

PubMed Central

Background and purpose Adverse reactions to metal debris have been reported to be a cause of pain in metal-on-metal hip arthroplasty. We assessed the incidence of both symptomatic and asymptomatic adverse reactions in a consecutive series of patients with a modern large-head metal-on-metal hip arthroplasty. Methods We studied the early clinical results and results of routine metal artifact-reduction MRI screening in a series of 79 large-head metal-on-metal hip arthroplasties (ASR; DePuy, Leeds, UK) in 68 patients. 75 hips were MRI scanned at mean 31 (12–52) months after surgery. Results 27 of 75 hips had MRI-detected metal debris-related abnormalities, of which 5 were mild, 18 moderate, and 4 severe. 8 of these hips have been revised, 6 of which were revised for an adverse reaction to metal debris, diagnosed preoperatively with MRI and confirmed histologically. The mean Oxford hip score (OHS) for the whole cohort was 21. It was mean 23 for patients with no MRI-based evidence of adverse reactions and 19 for those with adverse reactions detected by MRI. 6 of 12 patients with a best possible OHS of 12 had MRI-based evidence of an adverse reaction. Interpretation We have found a high early revision rate with a modern, large-head metal-on-metal hip arthroplasty. MRI-detected adverse rections to metal debris was common and often clinically “silent”. We recommend that patients with this implant should be closely followed up and undergo routine metal artifact-reduction MRI screening.

2011-01-01

124

Wound Drainage After Metal-On-Metal Hip Arthroplasty Secondary to Presumed Delayed Hypersensitivity Reaction  

Microsoft Academic Search

An emerging concern with metal-on-metal total hip arthroplasty is metal-induced hypersensitivity. Currently, this is a diagnosis of exclusion in patients with groin pain after metal-on-metal total hip arthroplasty. We describe a patient presenting nearly a year after arthroplasty with incisional drainage. Infection was presumed; but preoperative studies were nondefinitive, and the wound was explored. The operative cultures were negative; the

Mark D. Earll; Patrick G. Earll; Russell S. Rougeux

2011-01-01

125

Metal-on-Metal Hip Resurfacing Arthroplasty  

PubMed Central

Background Metal-on-metal (MOM) hip resurfacing arthroplasty (HRA) is in clinical use as an appropriate alternative to total hip arthroplasty in young patients. In this technique, a metal cap is placed on the femoral head to cover the damaged surface of the bone and a metal cup is placed in the acetabulum. Objectives The primary objective of this analysis was to compare the revision rates of MOM HRA using different implants with the benchmark set by the National Institute of Clinical Excellence (NICE). The secondary objective of this analysis was to review the literature regarding adverse biological effects associated with implant material. Review Methods A literature search was performed on February 13, 2012, to identify studies published from January 1, 2009, to February 13, 2012. Results The revision rates for MOM HRA using 6 different implants were reviewed. The revision rates for MOM HRA with 3 implants met the NICE criteria, i.e., a revision rate of 10% or less at 10 years. Two implants had short-term follow-ups and MOM HRA with one of the implants failed to meet the NICE criteria. Adverse tissue reactions resulting in failure of the implants have been reported by several studies. With a better understanding of the factors that influence the wear rate of the implants, adverse tissue reactions and subsequent implant failure can be minimized. Many authors have suggested that patient selection and surgical technique affect the wear rate and the risk of tissue reactions. The biological effects of high metal ion levels in the blood and urine of patients with MOM HRA implants are not known. Studies have shown an increase in chromosomal aberrations in patients with MOM articulations, but the clinical implications and long-term consequences of this increase are still unknown. Epidemiological studies have shown that patients with MOM HRA implants did not have an overall increase in mortality or risk of cancer. There is insufficient clinical data to confirm the teratogenicity of MOM implants in humans. Conclusions Metal-on-metal HRA can be beneficial for appropriately selected patients, provided the surgeon has the surgical skills required for performing this procedure. Plain Language Summary There are many young patients with hip diseases who need to have hip replacement surgery. Although a traditional hip replacement is an acceptable procedure for these patients, some surgeons prefer using a newer technique in young patients called hip resurfacing. In this technique, instead of removing the head of the femoral bone, a metal cap is placed on the femoral head to cover the damaged surface of the bone and a metal cup is placed in the hip socket, similar to the cups used in traditional hip replacement. The analysis of the revision rates (i.e., how soon and in how many patients the surgery needs to be redone) and safety of resurfacing implants showed that generally these implants can last 10 years or more for the majority of young people. Good outcomes can be expected when skilled surgeons perform the surgery in properly selected patients. However, since these implants are made of metal (cobalt and chromium alloy), there is concern about excess metal debris production due to friction between the 2 metal components leading to high levels of metal ions in the blood and urine of patients. The production of metal debris may result in inflammation in the joint or development of a benign soft tissue mass leading to implant failure. However, it has been shown that this risk can be reduced by proper positioning of the implant and the careful selection of patients for this procedure. Little is known about the long-term biological effects of high levels of metal ions in the blood and urine of patients who have received metal implants. There is concern about potential increases in the risk of cancer and the risk of fetal abnormalities, but these effects have not been established yet. However, since cobalt and chromium can pass the placental barrier, implants that are not metal-on-metal are recommended for women at childbearing ages if they

Sehatzadeh, S; Kaulback, K; Levin, L

2012-01-01

126

Edge loading in metal-on-metal hips: low clearance is a new risk factor  

PubMed Central

The revision rate of large head metal-on-metal and resurfacing hips are significantly higher than conventional total hip replacements. The revision of these components has been linked to high wear caused by edge loading; which occurs when the head–cup contact patch extends over the cup rim. There are two current explanations for this; first, there is loss of entrainment of synovial fluid resulting in breakdown of the lubricating film and second, edge loading results in a large local increase in contact pressure and consequent film thickness reduction at the cup rim, which causes an increase in wear. This paper develops a method to calculate the distance between the joint reaction force vector and the cup rim – the contact patch centre to rim (CPCR) distance. However, the critical distance for the risk of edge loading is the distance from the contact patch edge to rim (CPER) distance. An analysis of explanted hip components, divided into edge worn and non-edge-worn components showed that there was no statistical difference in CPCR values, but the CPER value was significantly lower for edge worn hips. Low clearance hips, which have a more conformal contact, have a larger diameter contact patch and thus are more at risk of edge loading for similarly positioned hips.

Zografos, Angelos; Sayles, Ritchie S; Hart, Alister; Cann, Philippa

2012-01-01

127

Risk of cancer with metal-on-metal hip replacements: population based study  

PubMed Central

Objective To assess the risk of cancer associated with modern primary metal-on-metal hip replacements. Design Population based study. Setting Nationwide retrospective comparative register. Participants 10?728 patients who underwent metal-on-metal total hip arthroplasty and 18?235 patients who underwent conventional metal-on-polyethylene, ceramic-on-polyethylene, and ceramic-on-ceramic total hip arthroplasty (the non-metal-on-metal cohort) in the Finnish Arthroplasty Register 2001-10. Data on cancer cases up to 2010 for these cohorts were extracted from the Finnish Cancer Registry. Main outcome measures The relative risk of cancer was expressed as the ratio of observed to expected number of cases from the Finnish population—that is, the standardised incidence ratio. The relative risk of cancer in the metal-on-metal cohort compared with the non-metal-on-metal cohort was estimated with analyses of these ratios and Poisson regression. Results The overall risk of cancer in patients with metal-on-metal hip implants was similar to that in the Finnish population (378 observed v 400 expected, standardised incidence ratio 0.95, 95% confidence interval 0.85 to 1.04). The overall risk of cancer in patients with metal-on-metal hip implants was also no higher than in patients who had received non-metal-on-metal hip implants (relative risk 0.92, 0.81 to 1.05). Conclusions Metal-on-metal hip replacements are not associated with an increased overall risk of cancer during a mean follow-up of four years.

2012-01-01

128

Metal-on-Metal Hip Resurfacing  

Microsoft Academic Search

Hip resurfacing devices require a new radiographic evaluation technique owing to femoral components with short or no stems. Fourteen US surgeons implanted 1148 metal-on-metal hip resurfacing (HR) devices in a US-FDA-IDE clinical trial, which began in 2001. In this multi-center, prospective study, 337 patients (mean age, 50.1 years) were enrolled as a study group of unilateral HR arthroplasties. Radiographs of

Rama Ramakrishnan; William L. Jaffe; William R. Kennedy

2008-01-01

129

Analysis of 118 second-generation metal-on-metal retrieved hip implants  

Microsoft Academic Search

steolysis is due to particulate wear debris and is responsible for the long-term failure of total hip replacements. It has stimulated the development of alternative joint surfaces such as metal-on-metal or ceramic-on-ceramic implants. Since 1988 the second-generation metal-on-metal implant Metasul has been used in over 60 000 hips. Analysis of 118 retrieved specimens of the head or cup showed rates

H.-P. Sieber; C. B. Rieker; P. Köttig

1999-01-01

130

- and Heteroepitaxy of Metal on Metal Growth  

NASA Astrophysics Data System (ADS)

The atomistics of metal on metal growth is studied using time resolved STM, SPALEED and kinetic Monte-Carlo simulations (KMC). A comparison of the growth behavior seen with STM and KMC is used to show the influence of the fundamental diffusion steps on the morphology of the growing surface in the homoepitaxial system Fe on Fe(110). Especially the influence of a Schwoebel-Ehrlich barrier and an anisotropy in edge diffusion are shown. Details of the transition from a pseudomorphic layer to the relaxed bulk like structure is shown in the examples Fe on W(110). The transition proceeds stepwise and extends over several layers. It involves different metastable arrangements of the layer depending on the deposition temperature.

Köhler, U.; Jensen, C.; Reshöft, K.; Schindler, A. C.; Wolf, D. E.

2000-04-01

131

Clinical manifestations in ten patients with asymptomatic metal-on-metal hip arthroplasty with very high cobalt levels.  

PubMed

Reports of adverse reactions to metal particle debris with metal-on-metal (MoM) hip arthroplasty have increased recently. Apart from the formation of pseudotumours and higher revision rates, another major cause for concern are the systemic effects of metal ions. Several effects of elevated systemic cobalt ions have been reported (e.g. myocardial and neurological effects, hypothyroidism). All 643 patients who underwent a stemmed large head MoM total hip replacement in our clinic were screened with repeated whole blood samples of metal ions (cobalt, chromium). We included ten asymptomatic unrevised patients with the highest cobalt concentrations, determined at a minimum of three years after implantation. These patients were subjected to an extensive neurological and cardiological screening protocol. In addition, blood samples were taken to assess renal and thyroid function. Ten patients with a cobalt level of 18-153 µg/L (mean 46.8 µg/L) were included. Nine patients were female, mean age was 65 years (range 56-75). The mean follow-up period was 4.2 years (range 3.0-6.1). Seven patients had bilateral stemmed MoM hip arthroplasty. No signs or symptoms of neurological dysfunction, cardiomyopathy, or renal or thyroid dysfunction could be identified or attributed to elevated cobalt levels. The clinical relevance of this study is that after short-term follow-up highly elevated blood cobalt levels do not cause systemic effects in our population. Hence in asymptomatic patients metal ions appear not to be a significant factor in the decision of when to revise a MoM large head total hip replacement. PMID:23813157

van Lingen, Christiaan P; Ettema, Harmen B; Timmer, Jorik R; de Jong, Gosse; Verheyen, Cees C P M

2013-10-28

132

Metal-on-metal hip resurfacing: a critical review.  

PubMed

In this article, a concise review of the current literature on metal-on-metal hip resurfacing (MoMHR) is given. In contrast to conventional total hip arthroplasty, older age, female sex and small femoral head sizes predispose to failure. Neck fracture and metal wear-related complications account for the most frequent reasons for re-operations. Although the long-term consequences of metal ion release remain unknown, the increasing prevalence of soft tissue related problems with potentially devastating functional consequences in this younger patient group are of concern. Outcome after revision for metal wear related failure of MoMHR is poor. In our opinion, patients with this device should be managed in dedicated centers with facilities for data collection and monitoring. The majority of proposed advantages of MoMHR cannot be supported by the published evidence. PMID:20665040

Macpherson, Gavin J; Breusch, Steffen J

2011-01-01

133

Common femoral vein thrombosis caused by a metal-on-metal hip arthroplasty-related pseudotumor.  

PubMed

We present a case of a pseudotumor causing a deep femoral vein thrombosis 16 months after undergoing a metal-on-metal total hip arthroplasty. There is increasing concern over the effect of metal ions that are produced by wear in metal-on-metal hip arthroplasty systems. Recently, a number of articles have reported the development of an inflammatory pseudotumor causing a number of different problems early on in the lifespan of the implant necessitating revision surgery. This case reports the first presentation of a pseudotumor causing a serious venous thrombosis due to pressure effect and indicates further possible evidence for caution when considering metal-on-metal bearing hip arthroplasty. PMID:22425294

Parfitt, Daniel J; Wood, Simon N; Chick, Christopher M; Lewis, Peter; Rashid, Majid H; Evans, Aled Rhys

2012-09-01

134

Do Ion Levels In Hip Resurfacing Differ From Metal-on-metal THA at Midterm?  

Microsoft Academic Search

Background  Metal-on-metal Birmingham hip resurfacing (MOM-BHR) is an alternative to metal-on-metal total hip arthroplasty (MOM-THA),\\u000a especially for young and\\/or active patients. However, wear resulting in increased serum ion levels is a concern.\\u000a \\u000a \\u000a \\u000a \\u000a Questions\\/purposes  We asked whether (1) serum chromium (Cr), cobalt (Co), and molybdenum (Mo) concentrations would differ between patients with\\u000a either MOM-BHR or MOM-THA at 5 years, (2) confounding factors such as

A. Moroni; L. Savarino; M. Hoque; M. Cadossi; N. Baldini

2011-01-01

135

Failed Metal-on-Metal Hip Arthroplasties: A Spectrum of Clinical Presentations and Operative Findings  

Microsoft Academic Search

Background  A number of recent reports have described novel failure mechanisms of metal-on-metal bearings in total and resurfacing hip\\u000a arthroplasty. Hip arthroplasties with metal-on-metal articulations are also subject to the traditional methods of failure\\u000a seen with different bearing couples. There is currently little information in the literature to help guide timely clinical\\u000a evaluation and management of these patients.\\u000a \\u000a \\u000a \\u000a \\u000a Questions\\/purposes  We therefore describe

James A. Browne; C. Dustin Bechtold; Daniel J. Berry; Arlen D. Hanssen; David G. Lewallen

2010-01-01

136

Cancer incidence and cause-specific mortality in patients with metal-on-metal hip replacements in Finland  

PubMed Central

Background and purpose Metal-on-metal hip implants have been widely used, especially in the USA, Australia, England and Wales, and Finland. We assessed risk of death and updated data on the risk of cancer related to metal-on-metal hip replacements. Patients and methods A cohort of 10,728 metal-on-metal hip replacement patients and a reference cohort of 18,235 conventional total hip replacement patients were extracted from the Finnish Arthroplasty Register for the years 2001–2010. Data on incident cancer cases and causes of death until 2011 were obtained from the Finnish Cancer Registry and Statistics Finland. The relative risk of cancer and death were expressed as standardized incidence ratio (SIR) and standardized mortality ratio (SMR). SIR/SIR ratios and SMR/SMR ratios, and Poisson regression were used to compare the cancer risk and the risk of death between cohorts. Results The overall risk of cancer in the metal-on-metal cohort was not higher than that in the non-metal-on-metal cohort (RR = 0.91, 95% CI: 0.82–1.02). The risk of soft-tissue sarcoma and basalioma in the metal-on-metal cohort was higher than in the non-metal-on-metal cohort (SIR/SIR ratio = 2.6, CI: 1.02–6.4 for soft-tissue sarcoma; SIR/SIR ratio = 1.3, CI: 1.1–1.5 for basalioma). The overall risk of death in the metal-on-metal cohort was less than that in the non-metal-on-metal cohort (RR = 0.78, CI: 0.69–0.88). Interpretation The overall risk of cancer or risk of death because of cancer is not increased after metal-on-metal hip replacement. The well-patient effect and selection bias contribute substantially to the findings concerning mortality. Arthrocobaltism does not increase mortality in patients with metal-on-metal hip implants in the short term. However, metal-on-metal hip implants should not be considered safe until data with longer follow-up time are available.

2014-01-01

137

Metal-on-Metal Hip Arthroplasty: Does Early Clinical Outcome Justify the Chance of an Adverse Local Tissue Reaction?  

Microsoft Academic Search

Larger diameter metal-on-metal (MOM) bearing hips offer the possibility of low wear and reduced risk of dislocation. We reviewed\\u000a the first 126 patients (131 hips) who had a large-head (36-mm) MOM bearing surface to report the early clinical outcome and\\u000a especially to determine the occurrence of dislocation and wear-related concerns. The minimum followup was 5 years (mean, 5.6 years;\\u000a range, 5–7 years). We

Charles A. Engh Jr; Henry Ho

2010-01-01

138

THA Using Metal-on-Metal Articulation in Active Patients Younger Than 50 Years  

Microsoft Academic Search

The main concern of patients with longer life expectancies and of patients who are younger and more active is the longevity\\u000a of their total hip arthroplasty. We retrospectively reviewed 83 cementless total hip arthroplasties in 73 patients implanted\\u000a with metal-on-metal articulation. All patients were younger than 50 years old (average age, 41 years) at the time of the index\\u000a procedure, and 80%

Christian P. Delaunay; François Bonnomet; Philippe Clavert; Philippe Laffargue; Henri Migaud

2008-01-01

139

Metal on metal hip resurfacing arthroplasty  

Microsoft Academic Search

This paper explores the cost utility of metalon-metal hip resurfacing arthroplasty (MOM) as an alternative intervention to\\u000a total hip replacement or ‘watchful waiting’ for patients with advanced hip disease. Early implant failure among younger and\\u000a more active elderly patients can mean that the use of total hip replacement (THR) is delayed, with patients managed through\\u000a ‘watchful waiting’, a combination of

L. McKenzie; L. Vale; S. Stearns; K. McCormack

2003-01-01

140

Metal-on-metal: history, state of the art (2010).  

PubMed

The history of metal-on-metal bearing began with K. Mc Kee. Several "episodes" have marked the history of metal-on-metal articulations, and each has contributed to a better understanding of this type of tribology. But to date the indications for this bearing are debated and are subject to reservations because of the existence of permanently elevated levels of circulating metal ions. It therefore appears that the monitoring of our patients, the documentation of our revisions and the collaboration with our industry partners as well as communicating with our biology and pathology colleagues is necessary to help us solve these problems. PMID:21234564

Triclot, Philippe

2011-02-01

141

Metal-on-Metal Hip Arthroplasty Does Equally Well in Osteonecrosis and Osteoarthritis  

Microsoft Academic Search

Many previous reports suggest total hip arthroplasty performs suboptimally in young patients with osteonecrosis. We retrospectively\\u000a compared the performance of metal-on-metal articulation in a select group of 107 patients with 112 hips (98 uncemented and\\u000a 14 cemented stems) 60 years of age or younger with either osteonecrosis (27 patients, 30 hips) or primary osteoarthritis (80\\u000a patients, 82 hips). We evaluated all

Manish R. Dastane; William T. Long; Zhinian Wan; Lisa Chao; Lawrence D. Dorr

2008-01-01

142

Short-term results of the M 2a-taper metal-on-metal articulation  

Microsoft Academic Search

A polyethylene-free, metal-on-metal acetabular system (M2a-taper [Biomet, Inc., Warsaw, IN]) was designed in an effort to improve total hip arthroplasty (THA) longevity. Minimum 2-year follow-up results involving 72 polyethylene liner THAs and 78 metal liner THAs from a multicenter, randomized, controlled, investigational device exemption study are reported. Mean Harris hip scores of 95.54 (polyethylene liner group) and 95.23 (metal liner

Adolph V. Lombardi; Thomas H. Mallory; Michael M. Alexiades; John M. Cuckler; Philip M. Faris; Kenneth A. Jaffe; E. Michael Keating; Carl L. Nelson; Chitranjan S. Ranawat; Joseph Williams; Richard Wixson; Jodi F. Hartman; Susan G. Capps; Cheryl A. Kefauver

2001-01-01

143

Hip resurfacing: mid-term results of the last-generation metal-on-metal devices  

Microsoft Academic Search

Total hip resurfacing has long been conceptually attractive to both surgeons and patients. However, historically it has been\\u000a plagued by limited durability and marked acetabular bone loss. The recent development of wear-resistant bearings such as metal-on-metal\\u000a has led to renewed interest in hip resurfacing in the orthopaedic community. We report the clinical and radiological results\\u000a of 350 consecutive surface arthroplasties

S. Giannini; A. Moroni; M. Romagnoli; M. Cadossi

2007-01-01

144

Femoral Revision in Hip Resurfacing Compared With Large-Bearing Metal-on-Metal Hip Arthroplasty  

Microsoft Academic Search

It has been suggested that revision of the femoral component of hip resurfacing after femoral failure would be straightforward and have an outcome comparable to primary total hip arthroplasty (THA). We have compared the outcome of femoral side–only revision resurfacings to the results of primary modular large-bearing metal-on-metal THA. Fourteen consecutive patients underwent revision surgery of the failed femoral component,

Simon J. W. Garrett; Ben J. R. F. Bolland; Piers J. Yates; Edward M. H. Gardner; Jeremy M. Latham

2011-01-01

145

Ultrasound Screening of Periarticular Soft Tissue Abnormality Around Metal-on-Metal Bearings  

Microsoft Academic Search

Although metal hypersensitivity or pseudotumors are concerns for metal-on-metal (MoM) bearings, detailed pathologies of patterns, severity, and incidence of periprosthetic soft tissue lesions are incompletely understood. We examined the potential of ultrasound for screening of periarticular soft tissue lesions around MoM bearings. Ultrasound examinations were conducted in 88 hips (79 patients) with MoM hip resurfacings or MoM total hip arthroplasties

Takashi Nishii; Takashi Sakai; Masaki Takao; Hideki Yoshikawa; Nobuhiko Sugano

146

Metal Ion Release With Large-Diameter Metal-on-Metal Hip Arthroplasty  

Microsoft Academic Search

Preoperative and postoperative ion concentrations were measured in 29 metal-on-metal, large-diameter head total hip arthroplasty (LDH-THA) patients. Mean chromium, cobalt (Co), and titanium levels from LDH-THA were 1.3, 2.2, and 2.7 ?g\\/L at 12 months. The open femoral head design showed significantly higher Co concentrations than the closed design (3.0 vs 1.8 ?g\\/L, P = .037). Compared with previously published

Pascal-André Vendittoli; Traian Amzica; Alain G. Roy; Daniel Lusignan; Julien Girard; Martin Lavigne

2011-01-01

147

The results of metal-on-metal hip resurfacing in patients under 30 years of age.  

PubMed

Degenerative hip conditions most commonly affect older patients. However, many cases occur in younger patients. Total hip arthroplasty is the conventional approach; however, hip resurfacing is a viable option. Fifty-three metal-on-metal resurfacings in 46 patients under age 30 were performed. Patients had a variety of etiologies, and were followed clinically and radiographically with mean follow-up of 98.2 months. Clinical scores and x-rays were compared pre-operatively and post-operatively. The last follow-up SF-12 and UCLA scores significantly improved post-operatively (P<0.0001). Range of motion scores also improved (P<0.001), and the mean Harris Hip Score was 88. There were 6 revisions. The Kaplan-Meier survivorship estimate at 8 years was 95%. Metal-on-metal hip resurfacing appears to be an effective procedure for younger patients. Longer-term data are needed for confirmation. PMID:23433997

Woon, Regina P; Johnson, Alicia J; Amstutz, Harlan C

2013-06-01

148

Time-dependent release of cobalt and chromium ions into the serum following implantation of the metal-on-metal Maverick™ type artificial lumbar disc (Medtronic Sofamor Danek)  

Microsoft Academic Search

Introduction  In total hip endoprosthetics and consequently for TDA, metal-on-metal combinations are used with the aim of reducing wear\\u000a debris. In metal-on-metal TDA the release of metal ions has until now been secondary to the main discussion.\\u000a \\u000a \\u000a \\u000a Materials and methods  In order to investigate the ion release following the implantation of the metal-on-metal Maverick™ type artificial lumbar\\u000a disc we measured the serum

Alexander Zeh; Claudia Becker; Michael Planert; Peter Lattke; David Wohlrab

2009-01-01

149

Metal-on-metal surface replacement: a triumph of hope over reason: opposes.  

PubMed

Hip resurfacing has been performed for over a decade but still raises controversy as an alternative to traditional total hip arthroplasty (THA). Concerns exist about the potential complications of hip resurfacing, including femoral neck fracture and osteonecrosis of the femoral head. Recently, attention has been given to the metal-on-metal bearing of hip resurfacing with regard to production of metal ions, possible tissue necrosis, and rare instances of metal hypersensitivity. Given the success of the gold-standard THA, it is understandable why some surgeons believe metal-on-metal surface replacement to be "a triumph of hope over reason." However, this article opposes that viewpoint, demonstrating that data exist to justify the practice of preserving bone in younger patients. Hip resurfacing can maintain femoral bone without the expense of removing additional acetabular bone by using modern implants with incremental sizing. Furthermore, many of the problems cited with the bearing couple (such as excess metal production) have been due to poor implant designs, which have now been removed from the market. Finally, we now realize that the metal-on-metal articulation is more sensitive to malposition; thus, good surgical technique and experience can solve many of the problems that have been cited in the past. National registry results confirm that in a select population, hip resurfacing performs comparably to THA, while fulfilling the goal of bone preservation. PMID:21902125

Su, Edwin P; Su, Sherwin L

2011-09-01

150

Metal-on-metal hip resurfacings—a radiological perspective  

Microsoft Academic Search

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

Zhongbo Chen; Hemant Pandit; Adrian Taylor; Harinderjit Gill; Simon Ostlere

2011-01-01

151

CoCrMo Metal-on-Metal Hip Replacements  

PubMed Central

After the rapid growth in the use of CoCrMo metal-on-metal hip replacements since the second generation was introduced circa 1990, metal-on-metal hip replacements have experienced a sharp decline in the last two years due to biocompatibility issues related to wear and corrosion products. Despite some excellent clinical results, the release of wear and corrosion debris and the adverse response of local tissues have been of great concern. There are many unknowns regarding how CoCrMo metal bearings interact with the human body. This perspective article is intended to outline some recent progresses in understanding wear and corrosion of metal-on-metal hip replacement both in-vivo and in-vitro. The materials, mechanical deformation, corrosion, wear-assisted corrosion, and wear products will be discussed. Possible adverse health effects caused by wear products will be briefly addressed, as well as some of the many open questions such as the detailed chemistry of corrosion, tribochemical reactions and the formation of graphitic layers. Nowadays we design almost routinely for high performance materials and lubricants for automobiles; humans are at least as important. It is worth remembering that a hip implant is often the difference between walking and leading a relatively normal life, and a wheelchair.

Liao, Yifeng; Hoffman, Emily; Wimmer, Markus; Fischer, Alfons; Jacobs, Joshua; Marks, Laurence

2012-01-01

152

The effectiveness of metal on metal hip resurfacing: a systematic review of the available evidence published before 2002  

Microsoft Academic Search

BACKGROUND: Conventional total hip replacement (THR) may be felt to carry too high a risk of failure over a patient's lifetime, especially in young people. There is increasing interest in metal on metal hip resurfacing arthroplasty (MoM) as this offers a bone-conserving option for treating those patients who are not considered eligible for THR. We aim to evaluate the effectiveness

Laura Wyness; Luke Vale; Kirsty McCormack; Adrian Grant; Miriam Brazzelli

2004-01-01

153

Perivascular and Diffuse Lymphocytic Inflammation are not Specific for Failed Metal-on-metal Hip Implants  

Microsoft Academic Search

Background  Several studies suggest that histologic findings from tissues obtained at revision arthroplasty for failed metal-on-metal\\u000a (MOM) total hip implants may reflect an immune reaction to particles or ions in some patients. However, only a limited number\\u000a of cases without MOM implants were reported as controls in those studies.\\u000a \\u000a \\u000a \\u000a \\u000a Questions\\/purposes  The purpose of this study is to better define the extent and

Takaaki Fujishiro; Dirk Jan F. Moojen; Naomi Kobayashi; Wouter J. A. Dhert; Thomas W. Bauer

2011-01-01

154

Metal-on-metal joint bearings and hematopoetic malignancy.  

PubMed

This is a review of the hip arthroplasty era. We concentrate on new metal bearings, surface replacements, and the lessons not learned, and we highlight recent reports on malignancies and joint implants. A low incidence of blood malignancies has been found in bone marrow taken at prosthetic surgery. The incidence is increased after replacement with knee implants that release very low systemic levels of metal ions. A carcinogenic effect of the high levels of metal ions released by large metal-on-metal implants cannot be excluded. Ongoing Swedish implant registry studies going back to 1975 can serve as a basis for evaluation of this risk. PMID:23140092

Wagner, Philippe; Olsson, Håkan; Ranstam, Jonas; Robertsson, Otto; Zheng, Ming Hao; Lidgren, Lars

2012-12-01

155

Metal-on-metal joint bearings and hematopoetic malignancy  

PubMed Central

Abstract This is a review of the hip arthroplasty era. We concentrate on new metal bearings, surface replacements, and the lessons not learned, and we highlight recent reports on malignancies and joint implants. A low incidence of blood malignancies has been found in bone marrow taken at prosthetic surgery. The incidence is increased after replacement with knee implants that release very low systemic levels of metal ions. A carcinogenic effect of the high levels of metal ions released by large metal-on-metal implants cannot be excluded. Ongoing Swedish implant registry studies going back to 1975 can serve as a basis for evaluation of this risk.

2012-01-01

156

Pseudotumours associated with metal-on-metal hip resurfacings.  

PubMed

We report 17 patients (20 hips) in whom metal-on-metal resurfacing had been performed and who presented with various symptoms and a soft-tissue mass which we termed a pseudotumour. Each patient underwent plain radiography and in some, CT, MRI and ultrasonography were also performed. In addition, histological examination of available samples was undertaken. All the patients were women and their presentation was variable. The most common symptom was discomfort in the region of the hip. Other symptoms included spontaneous dislocation, nerve palsy, a noticeable mass or a rash. The common histological features were extensive necrosis and lymphocytic infiltration. To date, 13 of the 20 hips have required revision to a conventional hip replacement. Two are awaiting revision. We estimate that approximately 1% of patients who have a metal-on-metal resurfacing develop a pseudotumour within five years. The cause is unknown and is probably multifactorial. There may be a toxic reaction to an excess of particulate metal wear debris or a hypersensitivity reaction to a normal amount of metal debris. We are concerned that with time the incidence of these pseudotumours may increase. Further investigation is required to define their cause. PMID:18591590

Pandit, H; Glyn-Jones, S; McLardy-Smith, P; Gundle, R; Whitwell, D; Gibbons, C L M; Ostlere, S; Athanasou, N; Gill, H S; Murray, D W

2008-07-01

157

Noninflammatory pseudotumor simulating venous thrombosis after metal-on-metal hip resurfacing.  

PubMed

Metal-on-metal hip resurfacing has become a widespread procedure, especially in young, physically active patients. Pseudotumor is a new complication that can occur after hip resurfacing and metal-on-metal total hip arthroplasty (THA). This article presents a case of a 37-year-old woman who underwent metal-on-metal resurfacing of the left hip for symptomatic osteoarthritis. Twelve months following implantation, the patient reported painless swelling of the left lower leg. There was no clinical evidence of a deep venous thrombosis. Ultrasound and computed tomography showed a solid cystic lesion in the iliopsoas muscle, which communicated with the hip joint and compressed the external iliac vein. As a consequence, the cystic lesion was resected marginally. A few months later, the patient reported some discomfort in the groin and symptoms of instability, metallic clicking, and a restricted range of motion. Clinical and radiological examination revealed normal findings. Determining the serum concentration of cobalt and chromium revealed high increased levels of these metal ions. Ten months following excision of the pseudotumor, the patient reported recurrent swelling of the left lower leg. Computed tomography of the affected area showed a lobulated cystic formation; therefore, a relapse was suspected. At the second revision, the mass was excised and the implant was revised to a conventional ceramic-on-ceramic THA. At 30-month follow-up, the patient was doing well and there were no signs of local recurrence. Additionally, the metal ion levels of cobalt and chromium in the blood had significantly decreased. PMID:21956066

Maurer-Ertl, Werner; Friesenbichler, Joerg; Liegl-Atzwanger, Bernadette; Kuerzl, Gerda; Windhager, Reinhard; Leithner, Andreas

2011-10-01

158

Zweymueller with metal-on-metal articulation: clinical, radiological and histological analysis of short-term results  

Microsoft Academic Search

Background. This is a prospective study. Methods. A total of 266 consecutive patients, who received 350 third-generation Zweymueller-SL total hip arthroplasties with metal-on-metal articulation for primary or secondary osteoarthritis, was followed and evaluated clinically, radiologically and histologically. The age of the patients at the time of surgery was 55Nj years, (range 25-70 years). Seven ( 3%) patients did not return

Panagiotis Korovessis; Georgios Petsinis; Maria Repanti

2003-01-01

159

Metal Ion Concentrations in Body Fluids after Implantation of Hip Replacements with Metal-on-Metal Bearing - Systematic Review of Clinical and Epidemiological Studies  

PubMed Central

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 indication for hip resurfacing arthroplasty. Patients with implanted MoM-bearing should receive regular and standardized monitoring of metal ion concentrations. Further research is indicated especially with regard to potential systemic reactions due to accumulation of metal products.

Hartmann, Albrecht; Hannemann, Franziska; Lutzner, Jorg; Seidler, Andreas; Drexler, Hans; Gunther, Klaus-Peter; Schmitt, Jochen

2013-01-01

160

Investigation on stick phenomena in metal-on-metal hip joints after resting periods.  

PubMed

Insufficient understanding of tribological behaviour in total joint arthroplasty is considered as one of the reasons for prosthesis failure. Contrary to the continuous motion input profiles of hip simulators, human locomotion contains motion interruptions. These occurring resting periods can cause stick phenomena in metal-on-metal hip joints. The aim of the present study was to investigate the tribological sensitivity of all-metal bearings to motion interruptions on in vitro test specimens and retrieved implants. Friction and wear with and without resting periods were quantified. Unlike the metal-on-polyethylene joints, the static friction of metal-on-metal joints increased up to micros = 0.3 with rest, while wear appeared to be unaffected. This effect is caused by the interlocking of firmly adhered carbon layers, which were generated from the protein-containing lubricant through tribochemical reactions. Since more than 80 per cent of the retrieved implants exhibited macroscopically visible carbon layers, the increase in friction presumably also occurs under physiological conditions, which is then transferred to the bone-implant interface. These recurrent tangential stress peaks should be considered for the design features of the cup-bone interface, in particular when larger-sized implant heads are used. PMID:16669389

Wimmer, M A; Nassutt, R; Sprecher, C; Loos, J; Täger, G; Fischer, A

2006-02-01

161

Island and Multilayer Growth of Metals on Metals:. Experiments and Computer Simulations  

NASA Astrophysics Data System (ADS)

We review the current understanding of growth of metals on metal films prepared in far-from-equilibrium conditions. Recent experimental and computational studies of metal-on-metal growth are presented and physical/chemical factors controlling this type of growth are identified and discussed. The technique of atom beam scattering to probe thin film growth in situ and in real time is illustrated in detail with selected results of a study of metal-on-metal heteroepitaxial growth.

Vidali, Gianfranco

162

Metal-on-Metal Bearings and Hypersensitivity in Patients with Artificial Hip Joints A CLINICAL AND H ISTOMORPHOLOGICAL S TUDY  

Microsoft Academic Search

Background: Some patients who have a total hip replacement with a second-generation metal-on-metal articulation have persistent or early recurrence of preoperative symptoms. Characteristic histological changes in the peripros- thetic tissues suggested the development of an immunological response. Therefore, in order to determine the rele- vance of these symptoms, we performed a study of the clinical data and periprosthetic tissues associated

HANS-GEORG WILLERT; GOTTFRIED H. BUCHHORN; AFSHIN FAYYAZI; RENATA FLURY; MARKUS WINDLER; GEORG KÖSTER; CHRISTOPH H. LOHMANN

163

Characterisation of wear particles produced by metal on metal and ceramic on metal hip prostheses under standard and microseparation simulation  

Microsoft Academic Search

The failure of metal on polyethylene total hip replacements due to wear particle induced osteolysis and late aseptic loosening\\u000a has focused interest upon alternative bearings, such as metal on metal implants. A recent advance in this field has been the\\u000a development of a novel ceramic on metal implant. The characteristics of the wear particles generated in this low-wearing bearing\\u000a have

Christopher Brown; Sophie Williams; Joanne L Tipper; John Fisher; Eileen Ingham

2007-01-01

164

Adsorbate interactions in metal-on-metal growth  

NASA Astrophysics Data System (ADS)

Highly anomalous values for the preexponential factor in atomic surface diffusion rates---deviating many orders of magnitude from theoretical results---have recently been inferred from scanning tunneling microscopy growth experiments. Performing a full kinetic Monte Carlo (KMC) analysis of the growth of Al/Al(111) based on exclusively first-principles density-functional data, we show how long-ranged adsorbate interactions invalidate the standard nucleation theory approach to analyzing experimental island-density data. When adatom-adatom interactions are properly accounted for in the analysis of experimental data, the prefactor anomaly is lifted, and deduced prefactors are in good agreement with theoretical values. The interactions are quantified for three metal-on-metal systems: Al/Al(111), Cu/Cu(111) and Al/Al(100). In all cases, adatoms are seen to repel each other when a few lattice distances apart. In a growth process, this results in the postponing of nucleation and thereby an increase of the island density, as confirmed in KMC simulations.

Ovesson, Staffan; Bogicevic, Alexander; Lundqvist, Bengt I.

2001-03-01

165

[Release of metals from metal-on-metal hip prostheses].  

PubMed

The present study examined blood and urinary concentrations of Cr and Co in 30 patients with metal-on-metal hip prostheses without signs of wear and 6 patients with prosthetic bearing and clear signs of wear and metallosis. The determination in biological fluids showed in patients with not signs of wear the geometric mean concentration of metals only modestly increased (CoS 0.5 microg/l, CoU 5.7 microg/l, CrS 0.8 microg/l, CrU 3.4 microg/l) compared to the reference values, while the wear caused a significant increase in the concentration of both Co (CoS 94.6 microg/l, CoU 334.5 microg/l) and Cr (CrS 57.7 microg/l, CrU 89.4 microg/I). As the results, the not functioning implants are a risks to the patients and are associated with high levels of metals in biological fluids. Currently, the patients with metallosis had not signs and symptoms associated with metal toxicity, but high concentrations could to cause kidney, peripheral nervous system, heart, and thyroid damage. PMID:23393850

Nicolli, A; Chiara, F; Bortoletti, I; Pasqualato, F; Mongillo, M; Gambalunga, A; Biggi, F; Trevisan, A

2011-01-01

166

Understanding the role of corrosion in the degradation of metal-on-metal implants.  

PubMed

In metal-on-metal joints the primary concerns in terms of long-term durability relate to corrosion, wear, and their joint (tribocorrosion) effects. The release of ions through corrosion processes and nanoscale debris from wear processes can seriously affect joint integrity and can lead to an adverse biological reaction by the host. In this paper an integrated study of corrosion-wear interactions in serum, Dulbecco's Modified Eagle's Medium and 0.3 per cent NaCl has demonstrated that the biological nature of the fluid affects the total degradation rate and also the level of wear-corrosion interactions. The specific action of proteins in corrosion and tribocorrosion for high-carbon Co-Cr-Mo and low-carbon Co-Cr-Mo alloys is discussed. PMID:16669385

Yan, Y; Neville, A; Dowson, D

2006-02-01

167

Histology of failed metal-on-metal hip arthroplasty; three distinct sub-types.  

PubMed

The histological specimens from 29 failed metal-on-metal (MoM) hip arthroplasties treated at our institution were reviewed. Five patients had a failed MoM total hip arthroplasty (THA), and 24 patients a failed hip resurfacing. Clinical and radiographic features of each hip were correlated with the histological findings.We report three major histological subtypes. Patients either have a macrophage response to metal debris, a lymphocytic response (ALVAL) or a mixed picture of both. In addition we observe that the ALVAL response is located deep within tissue specimens, and can occur in environments of low wear debris. The macrophage response is limited to the surface of tissue specimens, with normal underlying tissue. Patients with subsequently confirmed ALVAL underwent revision surgery sooner than patients whose histology confirms a macrophage response (3.8 vs. 6.9 years p<0.05). Both histological subtypes (ALVAL and macrophage dominant) are responsible for abnormal soft tissue swellings. PMID:24500829

Berstock, James R; Baker, Richard P; Bannister, Gordon C; Case, C Patrick

2014-05-22

168

The composition of tribofilms produced on metal-on-metal hip bearings.  

PubMed

Following wear testing in a hip simulator, the bearing surfaces of 36 mm metal on metal total hip replacements showed the formation of tribochemical layers. These layers were investigated in a transmission electron microscope, and analysis was performed using electron energy loss spectroscopy, energy dispersive x-rays and selected area electron diffraction. The tribofilm formed at the edge of the wear scar was 100 s of nanometres thick and contained cobalt sulphide particles embedded within. The film itself was rich in carbon, and appeared to contain no long range graphitic ordering when analysed with electron energy loss spectroscopy, and the spectra gathered from the tribofilm closely resembled those collected from amorphous carbon. The location at which the most substantial tribological layers formed may be explained by the formation of a blunt wedge at the edge of the wear scar following conformal changes to the bearing surfaces. PMID:24333026

Hesketh, James; Ward, Michael; Dowson, Duncan; Neville, Anne

2014-02-01

169

On the inflammatory response in metal-on-metal implants  

PubMed Central

Background Metal-on-metal implants are a special form of hip endoprostheses that despite many advantages can entail serious complications due to release of wear particles from the implanted material. Metal wear particles presumably activate local host defence mechanisms, which causes a persistent inflammatory response with destruction of bone followed by a loosening of the implant. To better characterize this inflammatory response and to link inflammation to bone degradation, the local generation of proinflammatory and osteoclast-inducing cytokines was analysed, as was systemic T cell activation. Methods By quantitative RT-PCR, gene expression of cytokines and markers for T lymphocytes, monocytes/macrophages and osteoclasts, respectively, was analysed in tissue samples obtained intraoperatively during exchange surgery of the loosened implant. Peripheral T cells were characterized by cytofluorometry before surgery and 7 to 10 days thereafter. Results At sites of osteolysis, gene expression of cathepsin K, CD14 and CD3 was seen, indicating the generation of osteoclasts, and the presence of monocytes and of T cells, respectively. Also cytokines were highly expressed, including CXCL8, IL-1ß, CXCL2, MRP-14 and CXCL-10. The latter suggest T cell activation, a notion that could be confirmed by detecting a small, though conspicuous population of activated CD4+ cells in the peripheral blood T cells prior to surgery. Conclusion Our data support the concept that metallosis is the result of a local inflammatory response, which according to histomorphology and the composition of the cellular infiltrate classifies as an acute phase of a chronic inflammatory disease. The proinflammatory environment, particularly the generation of the osteoclast-inducing cytokines CXCL8 and IL1-ß, promotes bone resorption. Loss of bone results in implant loosening, which then causes the major symptoms of metallosis, pain and reduced range of motion.

2014-01-01

170

Metal-on-metal surface replacement: a triumph of hope over reason: affirms.  

PubMed

Metal-on-metal hip resurfacing offers some potential for total hip arthroplasty (THA) in the young patient. However, short- and intermediate-term results of the currently available implants have failed to demonstrate advantage over conventional THA. The risks of femoral neck fracture or avascular necrosis have been disappointing early limitations of the procedure. The Australian Joint Registry reports a 5-year revision rate of all hip resurfacings of 3.8%, compared with conventional THAs at 2.8%, and a 9-year cumulative revision rate of 7.2% for hip resurfacings. Recent reports of femoral neck erosion and pseudotumors associated with resurfacing have raised concern about the survivorship of the procedure in some patients. Recently, the British Medicines and Healthcare Product Regulatory Agency issued an alert over adverse reactions associated with metal-on-metal THAs, with particular concern expressed about hip resurfacings. Acetabular bone stock may not be conserved when large-diameter femoral head components are used, depending on the surgical technique and implant design. In hip resurfacing, the minimum diameter femoral component avoids notching of the femoral neck; thus, larger diameter acetabular components may be necessary to accommodate the femoral component. Hip resurfacing is contraindicated in cases of avascular necrosis of the femoral head, especially with cysts >1 cm in diameter, with severe slipped capital femoral epiphysis, and in some posttraumatic arthroses; furthermore, the biomechanics of the resurfaced hip appear to be less reliably restored than with conventional THA. The hypothesis that resurfacing is a more conservative procedure than conventional THA remains unproven at this time. Given the documented intermediate failure rates of resurfacing, metal-on-polyethylene is the more successful implant choice. PMID:21902124

Cuckler, John M

2011-09-01

171

Cementless metal-on-metal hip arthroplasty in patients less than 50 years of age  

Microsoft Academic Search

Thirty-nine cementless hip arthroplasties using metal-on-metal articulation were consecutively implanted in 30 patients less than 50 years of age and compared with a matched control group (by age, diagnosis, Devane activity, and Harris hip scores) of cementless arthroplasties using ceramic-on-polyethylene articulation. The Harris hip score at follow-up (minimum 5 years) for the metal-on-metal was 94.9 (range, 74–100). After the same

Henri Migaud; Alexandre Jobin; Christophe Chantelot; François Giraud; Philippe Laffargue; Antoine Duquennoy

2004-01-01

172

Incidence of Groin Pain After Metal-on-Metal Hip Resurfacing  

Microsoft Academic Search

Metal-on-metal hip resurfacing is offered as an alternative to traditional THA for the young and active adult with advanced\\u000a osteoarthritis. However, patients undergoing hip resurfacing may be predisposed to persistent groin pain due to insufficient\\u000a head\\/neck offset, an uncovered acetabular component, or both. We therefore determined the incidence of groin pain after metal-on-metal\\u000a hip resurfacing, its impact on patient function,

Ahmad Bin Nasser; Paul E. BeauleMD; Michelle O’Neill; Paul R. Kim; Anna Fazekas

2010-01-01

173

Does Ion Release Differ Between Hip Resurfacing and Metal-on-metal THA?  

Microsoft Academic Search

Modern metal-on-metal hip resurfacing was introduced as a bone-preserving method of joint reconstruction for young and active\\u000a patients; however, the large diameter of the bearing surfaces is of concern for potential increased metal ion release. We\\u000a hypothesized there were no differences in serum concentrations of chromium, cobalt, and molybdenum between patients who had\\u000a metal-on-metal hip resurfacing (Group A; average head

Antonio Moroni; Lucia Savarino; Matteo Cadossi; Nicola Baldini; Sandro Giannini

2008-01-01

174

Immune responses correlate with serum-metal in metal-on-metal hip arthroplasty  

Microsoft Academic Search

Cell-mediated hypersensitivity associated with metal components may be related to levels of implant debris. We tested this hypothesis by comparing lymphocyte reactivity to soluble Co, Cr, Ni, and Ti of patients with metal-on-polyethylene and metal-on-metal arthroplasties with healthy controls, and patients with osteoarthritis. The metal-on-metal group (n=9) demonstrated significantly elevated serum Co and Cr concentrations (13- and 58-fold, P5, P2.5,

Nadim James Hallab; Shelley Anderson; Marco Caicedo; Anastasia Skipor; Pat Campbell; Joshua J. Jacobs

2004-01-01

175

Bearing surfaces for hip arthroplasty - is metal-on-metal a passing fancy?  

PubMed

Metal-on-metal bearings have had popularity that has waxed and waned over the years. The advantages realized relative to wear resistance and strength had been offset by early failures, manufacturing difficulty, and most recently by adverse soft tissue responses to the metallic debris. The bearing's history, evolution, advantages and disadvantages will be discussed in attempt to answer the question: is metal-on-metal a passing fancy? PMID:23065801

Lee, Reginald K; Nevelos, Jim; Vigdorchik, Jonathan; Markel, David C

2012-12-01

176

Tribology of Metal-on-Metal Bearings at High Inclination Angles  

Microsoft Academic Search

\\u000a Although metal-on-metal hip bearings generally experience low wear in vivo and in simulator testing, high cup inclination\\u000a angle has been shown to dramatically increase wear. A recent study has shown that metal-on-metal (MoM) bearings converge to\\u000a a specific contact area regardless of bearing size, clearance, or even contact mode. This evidence points to a relationship\\u000a between contact pressure and wear

Reginald Lee; Aiguo Wang; Aaron Essner; Shirong Ge

177

Serum and urine metal levels in patients with metal-on-metal surface arthroplasty  

Microsoft Academic Search

The resurgence of metal-on-metal articulating surfaces for hip arthroplasty has also heightened concerns about the degree and magnitude of metal particle generation and the accompanying increase in circulating metal ion concentrations. In this study, we measured the concentration of chromium in serum and urine and the concentration of cobalt in serum in twenty-five patients with modern metal-on-metal surface arthroplasty of

Anastasia K. Skipor; Patricia A. Campbell; Leslie M. Patterson; Harlan C. Anstutz; Thomas P. Schmalzried; Joshua J. Jacobs

2002-01-01

178

Mechanisms of hole formation in metal-on-metal epitaxial systems: Rh/Ag(0 0 1)  

NASA Astrophysics Data System (ADS)

We present a study of mechanisms for surface hole formation during heterogeneous, metal-on-metal epitaxial growth with application to the system Rh/Ag(0 0 1). Three mechanisms are proposed and investigated via a Monte Carlo kinetics simulation based on a simple model for the atomic-level kinetics. It is found that the dominant mechanism of hole formation in this system involves the growth of vacancy islands via an upward exchange diffusion move. First principles total energy computations confirm the plausibility of the explanation.

Roelofs, L. D.; Chipkin, D. A.; Rockwell, C. J.; Behm, R. J.

2003-02-01

179

Metal Ion release with large-diameter metal-on-metal hip arthroplasty.  

PubMed

Preoperative and postoperative ion concentrations were measured in 29 metal-on-metal, large-diameter head total hip arthroplasty (LDH-THA) patients. Mean chromium, cobalt (Co), and titanium levels from LDH-THA were 1.3, 2.2, and 2.7 ?g/L at 12 months. The open femoral head design showed significantly higher Co concentrations than the closed design (3.0 vs 1.8 ?g/L, P = .037). Compared with previously published ion levels from a hip resurfacing system presenting the same bearing characteristics, Co levels were significantly higher in LDH-THA (2.2 vs 0.7 ?g/L, P < .001). This study has demonstrated that the addition of a sleeve with modular junctions and an open femoral head design of LDH-THA causes more Co release than bearing surface wear (157% and 67%, respectively). Even if no pathologic metal ion threshold level has been determined, efforts should be made to minimize its release. We recommend modification or abandonment of the modular junction and femoral head open design for this specific LDH-THA system. PMID:20206466

Vendittoli, Pascal-André; Amzica, Traian; Roy, Alain G; Lusignan, Daniel; Girard, Julien; Lavigne, Martin

2011-02-01

180

Tribolayer formation in a metal-on-metal (MoM) hip joint: an electrochemical investigation.  

PubMed

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?A/cm(2)). Further, polarization resistance (Rp:2.39±0.60M?/cm(2)) and capacitance (Cdl:15.20±0.75?F/cm(2)) indicated variation in corrosion kinetics for the tribolayer surface, that attributed to its structure and stability in a simulated body environment. PMID:24099949

Mathew, M T; Nagelli, C; Pourzal, R; Fischer, A; Laurent, M P; Jacobs, J J; Wimmer, M A

2014-01-01

181

Perivascular Lymphocytic Infiltration Is Not Limited to Metal-on-Metal Bearings  

Microsoft Academic Search

Background  Perivascular lymphocytic infiltration (PVLI) suggests an adaptive immune response. Metal hypersensitivity after THA is presumed\\u000a associated with idiopathic pain and aseptic loosening, but its incidence and relationship to metallic wear leading to revision\\u000a are unclear as are its presence and relevance in non-metal-on-metal arthroplasty.\\u000a \\u000a \\u000a \\u000a \\u000a Questions\\/purposes  We compared (1) incidence and severity of PVLI in failed hip metal-on-metal (MoM) to non-MoM implants

Vincent Y. Ng; Adolph V. Lombardi Jr; Keith R. Berend; Michael D. Skeels; Joanne B. Adams

2011-01-01

182

Does ion release differ between hip resurfacing and metal-on-metal THA?  

PubMed

Modern metal-on-metal hip resurfacing was introduced as a bone-preserving method of joint reconstruction for young and active patients; however, the large diameter of the bearing surfaces is of concern for potential increased metal ion release. We hypothesized there were no differences in serum concentrations of chromium, cobalt, and molybdenum between patients who had metal-on-metal hip resurfacing (Group A; average head diameter, 48 mm; median followup, 24 months) and patients who had 28-mm metal-on-metal THA (Group B; median followup, 25 months). Serum concentrations also were compared with concentrations in healthy subjects. We identified no differences in ion levels between Groups A and B. A distinction was made according to gender. Women showed a higher chromium release in Group A whereas men had a higher cobalt release in Group B. Values obtained from Group A were higher than those of the control subjects. Our data suggest metal-on-metal bearings for THA should not be rejected because of concern regarding potential increased metal ion release; however, patients with elevated ion levels, even without loosening or toxicity, could be at higher risk and should be followed up periodically. Level of Evidence: Level III, therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence. PMID:18196364

Moroni, Antonio; Savarino, Lucia; Cadossi, Matteo; Baldini, Nicola; Giannini, Sandro

2008-03-01

183

Metal Sensitivity as a Cause of Groin Pain in Metal-on-Metal Hip Resurfacing  

Microsoft Academic Search

We describe 4 patients pooled from our patient populations who presented with groin pain at different periods postoperatively after implantation of a metal-on-metal hip resurfacing. Each patient underwent exploratory surgery after radiographic imaging, hematologic testing, and microbiological assessment of joint aspirations failed to explain their symptoms. Samples of periprosthetic tissues revealed extensive amounts of lymphocytic infiltrates that were suggestive of

Pat Campbell; Andrew Shimmin; Len Walter; Michael Solomon

2008-01-01

184

Does Ion Release Differ Between Hip Resurfacing and Metal-on-metal THA?  

PubMed Central

Modern metal-on-metal hip resurfacing was introduced as a bone-preserving method of joint reconstruction for young and active patients; however, the large diameter of the bearing surfaces is of concern for potential increased metal ion release. We hypothesized there were no differences in serum concentrations of chromium, cobalt, and molybdenum between patients who had metal-on-metal hip resurfacing (Group A; average head diameter, 48 mm; median followup, 24 months) and patients who had 28-mm metal-on-metal THA (Group B; median followup, 25 months). Serum concentrations also were compared with concentrations in healthy subjects. We identified no differences in ion levels between Groups A and B. A distinction was made according to gender. Women showed a higher chromium release in Group A whereas men had a higher cobalt release in Group B. Values obtained from Group A were higher than those of the control subjects. Our data suggest metal-on-metal bearings for THA should not be rejected because of concern regarding potential increased metal ion release; however, patients with elevated ion levels, even without loosening or toxicity, could be at higher risk and should be followed up periodically. Level of Evidence: Level III, therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence.

Moroni, Antonio; Cadossi, Matteo; Baldini, Nicola; Giannini, Sandro

2008-01-01

185

Influence of the clearance on in-vitro tribology of large diameter metal-on-metal articulations pertaining to resurfacing hip implants.  

PubMed

Large-diameter metal-on-metal articulations may provide an opportunity for wear reduction in total hip implants because earlier studies have shown that the formation of a fluid film that completely separates the bearing surfaces is theoretically possible. In such a lubrication mode and under ideal conditions, there is theoretically no amount of wear. Studies have suggested that the two primary parameters controlling the lubrication mode are the diameter and the clearance of the articulation. The goal of the present study was to experimentally investigate the influence of these two parameters on the wear behavior of large-diameter metal-on-metal articulations pertaining to resurfacing hip implants. The results of this in vitro investigation showed that longer running-in periods and higher amounts of running-in wear were associated with larger clearances. PMID:15833451

Rieker, Claude B; Schön, Rolf; Konrad, Reto; Liebentritt, Gernot; Gnepf, Patric; Shen, Ming; Roberts, Paul; Grigoris, Peter

2005-04-01

186

Comparison of ceramic-on-metal and metal-on-metal hip prostheses under adverse conditions.  

PubMed

Ceramic-on-metal (COM) hip replacements, where the head is BIOLOX® Delta ceramic and the liner is CoCrMo alloy, have demonstrated reduced wear under standard simulator conditions compared to metal-on-metal (MOM) bearings. COM hips are now being used clinically around the world. MOM hip resurfacings have raised concerns regarding poor clinical performance and increased in vivo wear was associated with steeply inclined acetabular components and translationally malpositioned components. The aim of this study was to compare the wear rates of MOM and COM total hip prostheses under adverse edge-loading conditions in a hip simulator test. COM and MOM 36 mm hip prostheses were tested in a hip simulator, with liners mounted to provide a clinical inclination angle of 55°. A simplified gait cycle and microseparation conditions were applied for two million cycles in 25% new born calf serum. The overall mean volumetric wear rate of COM bearings under adverse conditions was 0.36 ± 0.55 mm³/million cycles; this was significantly less than MOM wear (1.32 ± 0.91 mm³/million cycles). Under these adverse conditions; the contact zone on the head intersects the rim of the cup causing substantially elevated contact stresses, disrupting the protective boundary and mixed lubrication regime causing changes in types and severity of wear mechanisms. In COM bearings, the harder head does not become damaged when there is lubricant starvation and wear does not accelerate. In conclusion, COM bearings showed reduced wear compared to MOM bearings under standard and adverse clinically relevant simulator conditions and COM bearings may provide an advantage over MOM bearings under edge-loading conditions clinically. PMID:23359608

Williams, Sophie; Al-Hajjar, Mazen; Isaac, Graham H; Fisher, John

2013-07-01

187

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

PubMed

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 analysis and clinical examination to study 14 unrevised hips (mean patient age 52.7 years, 46 to 68, 5 female, 7 male) with a pseudotumour and 23 hips (mean patient age 52.8 years, 38 to 69, 7 female, 16 male) without a pseudotumour. The mean post-operative time to the first MARS-MRI scan was 4.3 years (2.2 to 8.3), and mean time between the first and second MARS-MRI scan was eight months (6 to 12). At the second MRI scan, the grade of severity of the pseudotumour had not changed in 35 hips. One new pseudotumour (Anderson C2 score, moderate) was observed, and one pseudotumour was downgraded from C2 (moderate) to C1 (mild). In general, the characteristics of the pseudotumours hardly changed. Repeated MARS-MRI scans within one year in patients with asymptomatic pseudotumours after MoM hip resurfacing showed little or no variation. In 23 patients without pseudotumour, one new asymptomatic pseudotumour was detected. This is the first longitudinal study on the natural history of pseudotumours using MARS-MRI scans in hip resurfacing, and mirrors recent results for 28 mm diameter MoM total hip replacement. PMID:24293591

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

2013-12-01

188

New Insights into Wear and Biological Effects of Metal-on-Metal Bearings  

PubMed Central

Background: Despite the renewed interest in metal-on-metal implants in the past two decades, the underlying wear mechanisms and biological effects are still not fully understood. Methods: This paper first reviews the tribology of metal-on-metal bearings, bringing new insights into the interaction of wear and corrosion, and putting the characteristics and the potential origin of wear particles in perspective with the proposed wear mechanisms. It then summarizes the current knowledge on the biological effects of particles and metal ions in relation to these wear mechanisms. Results: Tribochemical reactions play an important role in the wear of metal-on-metal joints. The generated tribomaterial, which progressively forms by mechanical mixing of the uppermost nanocrystalline zone of the metal surface with proteins from the synovial fluid, governs the wear rate and influences the corrosive behavior of the bearing. Nanometer-sized wear particles may initially originate from the passivation layer covering the implant surface and then detach from this tribolayer. The inflammatory response observed surrounding metal-on-metal implants appears to be lower than that around metal-on-polyethylene implants. However, metallic byproducts, which can complex with proteins, may lead to a T lymphocyte-mediated hypersensitivity response. Conclusions: The tribolayer appears to have beneficial effects on the wear rate. Much information has been gained on wear particle characteristics, but the exact mechanisms of particle detachment remain to be further elucidated. Excessive wear along with a hypersensitivity response may be at the origin of the early adverse tissue reactions that have been recently reported in some patients with metal-on-metal implants. Clinical Relevance: Future development of new methods to improve the tribolayer retention and optimize the tribocorrosive properties of the implant may minimize the clinical impact of implant wear and immune responses.

Catelas, Isabelle; Wimmer, Markus A.

2011-01-01

189

Metal-on-metal bearings: the problem is edge-loading wear.  

PubMed

Metal-on-metal bearings are promoted as a low wear bearing alternative to traditional hip replacement bearings. While most in vitro studies support this, recent clinical reviews have found a significant number of early revisions in some designs of metal-on-metal bearings related to wear. Metal-on-metal bearings exhibit a bi-phasic wear pattern with high initial wear that generally settles down to low steady state wear. Previous publications from the authors have found that steady state wear occurs due to the formation of a critical conforming contact area. This contact area was found to be surprisingly constant regardless of bearing size, clearance, or even contact mode. The authors hypothesized that steady state wear may never be reached if formation of this critical conforming contact area is disrupted. Several hip simulator tests were performed to assess the wear performance of generic metal-on-metal samples at various angles of inclination. Three-dimensional modeling was performed on the generic bearing design as well as typical resurfacing and hemispherical bearing designs including various sizes and clearance ranges. Simulator results support the hypotheses, and wear rates were linear or accelerating when the critical contact area size could not be achieved due to its proximity to the rim of the bearing. Modeling studies show a correlation between bearing size and design and the maximum inclination angle allowed to reach steady state conditions. Smaller bearing size and shallower cup designs were found to reduce the maximum safe inclination angle and this corresponds to clinical observation of increased failure rates in these bearings. This simple method for assessing runaway wear risk can be utilized in the design of more robust and forgiving metal-on-metal bearings. PMID:21082578

Lee, Reginald K; Longaray, Jason; Essner, Aaron; Wang, Aiguo

2010-10-01

190

Patterns of Risk of Cancer in Patients with Metal-on-Metal Hip Replacements versus Other Bearing Surface Types: A Record Linkage Study between a Prospective Joint Registry and General Practice Electronic Health Records in England  

PubMed Central

Background There are concerns that metal-on-metal hip implants may cause cancer. The objective of this study was to evaluate patterns and timing of risk of cancer in patients with metal-on-metal total hip replacements (THR). Methods In a linkage study between the English National Joint Registry (NJR) and the Clinical Practice Research Datalink (CPRD), we selected all THR surgeries (NJR) between 2003 and 2010 (n?=?11,540). THR patients were stratified by type of bearing surface. Patients were followed up for cancer and Poisson regression was used to derive adjusted relative rates (RR). Results The risk of cancer was similar in patients with hip resurfacing (RR 0.69; 95% Confidence Interval [CI] 0.39–1.22) or other types of bearing surfaces (RR 0.96; 95% CI 0.64–1.43) compared to individuals with stemmed metal-on-metal THR. The pattern of cancer risk over time did not support a detrimental effect of metal hip implants. There was substantial confounding: patients with metal-on-metal THRs used fewer drugs and had less comorbidity. Conclusions Metal-on-metal THRs were not associated with an increased risk of cancer. There were substantial baseline differences between the different hip implants, indicating possibility of confounding in the comparisons between different types of THR implants.

Lalmohamed, Arief; MacGregor, Alexander J.; de Vries, Frank; Leufkens, Hubertus G. M.; van Staa, Tjeerd P.

2013-01-01

191

Metallosis-induced iliopsoas bursal cyst causing venous obstruction and lower-limb swelling after metal-on-metal THA.  

PubMed

The formation of iliopsoas bursal cystic lesions after total hip arthroplasty is an infrequently reported condition. This article describes an unusual complication of a current-generation metal-on-metal total hip arthroplasty.A woman presented with unilateral spontaneous lower-limb swelling that developed 5 years postoperatively. It occurred secondary to venous obstruction by a metallosis-induced iliopsoas bursal cyst associated with markedly elevated intralesional cobalt and chromium levels. Metal artifact reduction sequence magnetic resonance imaging showed that the bursal cyst was communicating with the hip joint and that it severely compressed the common femoral vein. Based on the findings of high local tissue metal ions and vertical cup positioning causing edge loading, the authors proposed an inflammatory reaction to metal debris that tracked into the iliopsoas bursa and formed a cyst. The patient underwent revision of the excessively vertical acetabular component and conversion to a ceramic-on-ceramic bearing interface, drainage of the bursal cyst, and synovectomy. No signs existed of local recurrence at 1-year follow-up.To the authors' knowledge, the occurrence of metallosis-induced iliopsoas bursitis with secondary pressure effects after contemporary metal-on-metal total hip arthroplasty has not been reported. When treating hip dysplasia, one must avoid maximizing cup-host bone contact at the risk of oververticalization. Iliopsoas bursal cystic lesions can lead to severe vascular compressive symptoms with no ominous radiographic findings. Physicians and orthopedic surgeons should be aware of the possibility of this complication in patients with unexplained unilateral lower-limb swelling. PMID:23218642

Algarni, Abdulrahman D; Huk, Olga L; Pelmus, Manuela

2012-12-01

192

Do the Potential Benefits of Metal-on-Metal Hip Resurfacing Justify the Increased Cost and Risk of Complications?  

Microsoft Academic Search

Background  Metal-on-metal hip resurfacing arthroplasty (MoM HRA) may offer potential advantages over total hip arthroplasty (THA) for\\u000a certain patients with advanced osteoarthritis of the hip. However, the cost effectiveness of MoM HRA compared with THA is\\u000a unclear.\\u000a \\u000a \\u000a \\u000a \\u000a Questions\\/purposes  The purpose of this study was to compare the clinical effectiveness and cost-effectiveness of MoM HRA to THA.\\u000a \\u000a \\u000a \\u000a Methods  A Markov decision model was constructed

Kevin J. Bozic; Christine M. Pui; Matthew J. Ludeman; Thomas P. Vail; Marc D. Silverstein

2010-01-01

193

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

PubMed

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. PMID:24655612

Lombardi, Adolph V

2014-04-01

194

Effects of metal-on-metal wear on the host immune system and infection in hip arthroplasty  

PubMed Central

Background and purpose Joint replacement with metal-on-metal (MOM) bearings have gained popularity in the last decades in young and active patients. However, the possible effects of MOM wear debris and its corrosion products are still the subject of debate. Alongside the potential disadvantages such as toxicity, the influences of metal particles and metal ions on infection risk are unclear. 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 by a possible antibiotic resistance and heavy metal co-selection mechanism. Interpretation Whether or not the combined effects of MOM wear products make MOM bearings less or more prone to infection requires investigation in the near future.

2010-01-01

195

Breast milk metal ion levels in a young and active patient with a metal-on-metal hip prosthesis.  

PubMed

Metal-on-metal resurfacing arthroplasty of the hip has been used increasingly over the last 10 years in younger active patients. The dissolution of the metal wear particles results in measurable increases in cobalt and chromium ions in the serum and urine of patients with a metal-on-metal bearing. We measured the cobalt, chromium, and molybdenum ion levels in urine; serum; and breast milk in a young and active patient with a metal-on-metal hip prosthesis after a pathologic fracture of the femoral neck. Metal-on-metal hip prosthesis leads to increasing levels of molybdenum in breast milk in the short-term follow-up. There are no increasing levels of chromium and cobalt ions in breast milk. Besides the already known elevated concentrations in serum of chromium and cobalt after implantation of a metal-on-metal hip prosthesis, we found no increasing levels of chromium and cobalt in urine. PMID:22868068

Nelis, Raymond; de Waal Malefijt, Jan; Gosens, Taco

2013-01-01

196

Formation of molten metal films during metal-on-metal slip under extreme interfacial conditions  

Microsoft Academic Search

The present paper describes results of plate-impact pressure-shear friction experiments conducted to study time-resolved growth of molten metal films during dry metal-on-metal slip under extreme interfacial conditions. By employing tribo-pairs comprising hard tool-steel against relatively low melt-point metals such as 7075-T6 aluminum alloys, interfacial friction stress ranging from 100 to 400MPa and slip speeds of approximately 100m\\/s have been generated.

Nai-Shang Liou; Makoto Okada; Vikas Prakash

2004-01-01

197

High-speed frictional slip at metal-on-metal interfaces  

Microsoft Academic Search

In this study plate-impact pressure-shear friction experiments are employed to investigate dynamic slip resistance and time-resolved growth of molten metal films during dry metal-on-metal slip under extreme interfacial conditions. By employing a tribo-pair comprising of a hard tool-steel against a relatively low melt-point metal (7075-T6 Al alloy), interfacial normal stress of up to 5GPa and slip speeds of approximately 250m\\/s

Fuping Yuan; Nai-Shang Liou; Vikas Prakash

2009-01-01

198

Retrieval Wear Analysis of Metal-on-Metal Hip Resurfacing Implants Revised Due to Pseudotumours  

Microsoft Academic Search

\\u000a Pseudotumours (soft-tissue masses relating to the hip joint) following metal-on-metal hip resurfacing arthroplasty (MoMHRA)\\u000a have been associated with elevated serum and hip aspirate metal ion levels, suggesting that pseudotumours occur when there\\u000a is increased wear. We aimed to quantify in vivo wear of implants revised for pseudotumours (8) and a control group of implants\\u000a (22) revised for other reasons of

Young-Min Kwon; Harinderjit S. Gill; David W. Murray; Amir Kamali

199

Cementless Acetabular Socket Revisions Using Metasul Metal-on-Metal Bearings  

Microsoft Academic Search

Thirty-four hips were treated with cementless acetabular socket revisions using a metal-on-metal bearing. The causes of revision were aseptic loosening in 33 hips and septic loosening in 1 hip. Revisions were performed for acetabular sockets in 28 hips and for acetabular sockets and femoral stems in 6 hips. Mean follow-up duration was 6.2 years (range, 4.0-9.1 years), and mean Harris

Kyung Soon Park; Taek Rim Yoon; Eun Kyoo Song; Keun Bae Lee

2010-01-01

200

Clinical Outcome of the Metal-on-Metal Hybrid Corin Cormet 2000 Hip Resurfacing System  

Microsoft Academic Search

This report extends the follow-up for the largest center of the first multicenter US Food and Drug Administration investigational device exemption study on metal-on-metal hip resurfacing arthroplasty up to 11 years. A single surgeon performed 373 hip resurfacing arthroplasties using the hybrid Corin Cormet 2000 system. The Kaplan-Meier survivorship at 11 years was 93% when revision for any reason was

Thomas P. Gross; Fei Liu; Lee A. Webb

201

Five-Year Results of Metal-on-Metal Resurfacing Arthroplasty in Asian Patients  

Microsoft Academic Search

Clinical results of 50 metal-on-metal resurfacing arthroplasties in 45 Japanese patients were evaluated to a minimum follow-up of 5 years. The predominant diagnosis was developmental dysplasia or dislocation of the hip (70%). One patient died of an unrelated cause and another was lost to follow-up. Two hips received revision surgery, including 1 femoral neck fracture and 1 septic loosening. In

Takashi Nishii; Nobuhiko Sugano; Hidenobu Miki; Masaki Takao; Tsuyoshi Koyama; Hideki Yoshikawa

2007-01-01

202

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

Microsoft Academic Search

Introduction  Resurfacing metal-on-metal hip arthroplasty is increasing in popularity, especially in younger patients. To date, studies\\u000a indicate that the procedure is associated with a good outcome in the medium-term. Formation of a peri-articuar mass is a rarely\\u000a reported complication. In this study we analyse the imaging findings in patients with resurfacing implants presenting to our\\u000a institution with peri-articular masses identified on

Christopher. S. J. Fang; Paul Harvie; Christopher L. M. H. Gibbons; Duncan Whitwell; Nicholas A. Athanasou; Simon Ostlere

2008-01-01

203

Transient elastohydrodynamic lubrication analysis of metal-on-metal hip implant under simulated walking conditions  

Microsoft Academic Search

The transient elastohydrodynamic lubrication (EHL) analysis was performed in this study for a typical metal-on-metal bearing employing a polyethylene backing underneath a metallic cup inlay under dynamic operating conditions of load and speed representative of normal walking. A ball-in-socket configuration was adopted to represent the articulation between the femoral head and the acetabular cup. The governing Reynolds and elasticity equations

F. Liu; Z. M. Jin; F. Hirt; C. Rieker; P. Roberts; P. Grigoris

2006-01-01

204

Immune Responses in Patients With Metal-on-Metal Hip Articulations  

Microsoft Academic Search

Metal-on-metal (MoM) hip bearings are being inserted into ever-younger patients. The effects on the immune system of chronic exposure are unknown. We investigated the immune response of patients with MoM hip bearings. In patients with MoM implants, the expression of antigen-presenting cell (APC) surface molecules (CD86 and HLA-DR) was seen to be significantly higher (P < .05) than control group.

Paul M. Whittingham-Jones; Edward Dunstan; Huwaidha Altaf; Stephen R. Cannon; Peter A. Revell; Timothy W. R. Briggs

2008-01-01

205

Effect of wear of bearing surfaces on elastohydrodynamic lubrication of metal-on-metal hip implants.  

PubMed

The effect of geometry change of the bearing surfaces owing to wear on the elastohydrodynamic lubrication (EHL) of metal-on-metal (MOM) hip bearings has been investigated theoretically in the present study. A particular MOM Metasul bearing (Zimmer GmbH) was considered, and was tested in a hip simulator using diluted bovine serum. The geometry of the worn bearing surface was measured using a coordinate measuring machine (CMM) and was modelled theoretically on the assumption of spherical geometries determined from the maximum linear wear depth and the angle of the worn region. Both the CMM measurement and the theoretical calculation were directly incorporated into the elastohydrodynamic lubrication analysis. It was found that the geometry of the original machined bearing surfaces, particularly of the femoral head with its out-of-roundness, could lead to a large reduction in the predicted lubricant film thickness and an increase in pressure. However, these non-spherical deviations can be expected to be smoothed out quickly during the initial running-in period. For a given worn bearing surface, the predicted lubricant film thickness and pressure distribution, based on CMM measurement, were found to be in good overall agreement with those obtained with the theoretical model based on the maximum linear wear depth and the angle of the worn region. The gradual increase in linear wear during the running-in period resulted in an improvement in the conformity and consequently an increase in the predicted lubricant film thickness and a decrease in the pressure. For the Metasul bearing tested in an AMTI hip simulator, a maximum total linear wear depth of approximately 13 microm was measured after 1 million cycles and remained unchanged up to 5 million cycles. This resulted in a threefold increase in the predicted average lubricant film thickness. Consequently, it was possible for the Metasul bearing to achieve a fluid film lubrication regime during this period, and this was consistent with the minimal wear observed between 1 and 5 million cycles. However, under adverse in vivo conditions associated with start-up and stopping and depleted lubrication, wear of the bearing surfaces can still occur. An increase in the wear depth beyond a certain limit was shown to lead to the constriction of the lubricant film around the edge of the contact conjunction and consequently to a decrease in the lubricant film thickness. Continuous cycles of a running-in wear period followed by a steady state wear period may be inevitable in MOM hip implants. This highlights the importance of minimizing the wear in these devices during the initial running-in period, particularly from design and manufacturing points of view. PMID:16225148

Liu, F; Jin, Z M; Hirt, F; Rieker, C; Roberts, P; Grigoris, P

2005-09-01

206

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

Microsoft Academic Search

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

Alister J. Hart; Ann Sandison; Paul Quinn; Barry Sampson; Kirk D. Atkinson; John A. Skinner; Angela Goode; Jonathan J. Powell; J. Frederick W. Mosselmans

2009-01-01

207

Recent advances in island and multilayer growth of metals on metals far from equilibrium  

NASA Astrophysics Data System (ADS)

In recent years, the study of growth of metal-on-metal homoepitaxial and heteroepitaxial films under far-from-equilibrium conditions (low substrate temperature and/or high deposition rate) has yielded quite surprising results. Under these conditions local thermodynamic equilibrium is not achieved, and kinetic influenced growth modes and film properties are often obtained. Here we present a review of a comprehensive study that we just completed on island nucleation and growth, manipulation of growth modes, and kinetic roughening of the heteroepitaxial growth of Pb on Cu(001) at low substrate temperature.

Vidali, Gianfranco; Zeng, Hong

1996-02-01

208

Dendritic islands in metal-on-metal epitaxy I. Shape transitions and diffusion at island edges  

NASA Astrophysics Data System (ADS)

The development of dendritic island shape instabilities observed during metal-on-metal epitaxy is investigated via a lattice-gas model for the low coverage regime. The key assumption is that island structure is controlled by the competition between shape equilibration due to adatom edge diffusion, and Mullins-Sekerka-type shape instability due to diffusion-limited aggregation of adatoms with islands. From comparison with scanning tunneling microscopy data (for the island density and average width of dendritic arms), we advance estimates of the energy barrier for edge diffusion in several systems.

Bartelt, M. C.; Evans, J. W.

1994-07-01

209

Histological Features of Pseudotumor-like Tissues From Metal-on-Metal Hips  

Microsoft Academic Search

Background  Pseudotumor-like periprosthetic tissue reactions around metal-on-metal (M-M) hip replacements can cause pain and lead to revision\\u000a surgery. The cause of these reactions is not well understood but could be due to excessive wear, or metal hypersensitivity\\u000a or an as-yet unknown cause. The tissue features may help distinguish reactions to high wear from those with suspected metal\\u000a hypersensitivity.\\u000a \\u000a \\u000a \\u000a \\u000a Questions\\/purposes  We therefore examined

Pat Campbell; Edward Ebramzadeh; Scott Nelson; Karren Takamura; Koen De Smet; Harlan C. Amstutz

2010-01-01

210

Metal-on-metal local tissue reaction is associated with corrosion of the head taper junction.  

PubMed

We evaluated taper corrosion in 36-mm diameter metal-on-metal (MOM) and metal-on-polyethylene (MOP) femoral heads from a single manufacturer retrieved for various reasons. Three reviewers visually graded taper corrosion with a 5-point scale on 19 MOM heads and 14 MOP heads. The MOM group had a higher corrosion score than the MOP group (mean, 3.5 vs 1.9; P < .001). There were 8 MOM heads (42%) and only 1 MOP head (7%) that demonstrated corrosion outside of the taper zone. Metal-on-metal patients revised secondary to adverse local tissue reactions (ALTRs) had greater scores than patients without ALTRs (mean, 4.36 vs 2.38; P < .01). Adverse local tissue reactions MOM patients were also likely to have corrosion outside of the taper junction. The corrosion score increased with implantation time, and at all time intervals, the corrosion score for the MOM group was greater. Because corrosion worsens with time, we are concerned that MOM ALTR failures will increase with longer follow-up. PMID:22554728

Fricka, Kevin B; Ho, Henry; Peace, William J; Engh, Charles A

2012-09-01

211

Surface engineering: a low wearing solution for metal-on-metal hip surface replacements.  

PubMed

Increased patient blood and serum levels of Co and Cr and dissemination of metal wear particles throughout organs and tissues are the primary concerns with metal-on-metal surface replacements. Surface engineering, providing a ceramic bearing surface on a metal substrate, could provide a solution. This study investigated thick (>10 microm) arc evaporation plasma vapor deposition chromium nitride (CrN) coated surface replacements in terms of wear, ion levels, and wear particles in a 10 million cycle hip simulator study, compared to a contemporary metal-on-metal surface replacement. The ion levels were measured by inductively coupled plasma mass spectroscopy. The wear particles were imaged by field emission gun scanning electron microscopy. The CrN-coated bearings had 80% lower wear than the MoM controls. The Cr and Co ion levels in the lubricant of the CrN bearings were 73 and 98% lower than in the MoM controls. The wear particles produced were in the nanometer size range and round to oval in morphology. The CrN coating could provide a reduction in the wear and ion release of MoM surface replacements, thereby reducing the perceived risks to the patient associated with these prostheses. PMID:19195030

Leslie, Ian J; Williams, Sophie; Brown, Chris; Anderson, James; Isaac, Graham; Hatto, Peter; Ingham, Eileen; Fisher, John

2009-08-01

212

Necrotic granulomatous pseudotumor following metal-on-metal hip arthroplasty: a potential mimic of sarcoma on fine needle aspiration cytology.  

PubMed

A 69-year-old female presented with left leg pain 4 months after total hip replacement for left hip joint protrusio acetabuli. A "cystic" mass lesion was identified radiologically in relation to the arthroplasty and an initial CT-guided core needle biopsy showed a spindle cell proliferation with associated necrosis, interpreted as suspicious for malignancy. A repeat CT-guided fine needle aspiration showed necrosis, "ghost" spindle cells, aggregates of histiocytes, giant cells, and inflammatory cells as well as scattered large atypical spindle cells. The simultaneously obtained core biopsy showed extensive necrosis with ghost spindle cells that was surrounded by CD68+ histiocytes, which in turn were surrounded by a predominantly CD3+, CD4+ lymphocytic infiltrate. A diagnosis of necrotic granulomatous pseudotumor was made after a diagnosis of sarcoma was initially entertained. This unusual tissue response is rarely seen after metal-on-metal arthroplasty, occurs more often in females and may represent a type-IV hypersensitivity reaction incited by very small-sized particulate metallic debris that forms haptens in association with serum proteins. PMID:22927292

Singh, Charanjeet; Kaplan, Alesia; Pambuccian, Stefan E

2012-08-01

213

Laboratory studies on the tribology of hard bearing hip prostheses: ceramic on ceramic and metal on metal.  

PubMed

Total hip replacements offer relief to a great many patients every year around the world. With an expected service life of around 25 years on most devices, and with younger and younger patients undergoing this surgery, it is of great importance to understand the mechanisms of their function. Tribological testing of both conventional and hard bearing joint combinations have been conducted in many centres throughout the world, and, after being initially abandoned owing to premature failures, hard bearing combinations have been revisited as viable options for joint replacements. Improved design, manufacturing procedures, and material compositions have led to improved performance over first-generation designs in both metal-on-metal and ceramic-on-ceramic hip prostheses. This paper offers a review of the work conducted in an attempt to highlight the most important factors affecting joint performance and tribology of hard bearing combinations. The tribological performance of these joints is superior to that of conventional metal- or ceramic-on-polymer designs. PMID:17315764

Vassiliou, K; Scholes, S C; Unsworth, A

2007-01-01

214

Formation of molten metal films during metal-on-metal slip under extreme interfacial conditions  

NASA Astrophysics Data System (ADS)

The present paper describes results of plate-impact pressure-shear friction experiments conducted to study time-resolved growth of molten metal films during dry metal-on-metal slip under extreme interfacial conditions. By employing tribo-pairs comprising hard tool-steel against relatively low melt-point metals such as 7075-T6 aluminum alloys, interfacial friction stress ranging from 100 to 400 MPa and slip speeds of approximately 100 m/ s have been generated. These relatively high levels of friction stress combined with high slip-speeds generate conditions conducive for interfacial temperatures to approach the melting point of the lower melt point metal (Al alloy) comprising the tribo-pair. A Lagrangian finite element code is developed to understand the evolution of the thermo-mechanical fields and their relationship to the observed slip response. The code accounts for dynamic effects, heat conduction, contact with friction, and full thermo-mechanical coupling. At temperatures below the melting point the material is described as an isotropic thermally softening elastic-viscoplastic solid. For material elements with temperatures in excess of the melt point a purely Newtonian fluid constitutive model is employed. The results of the hybrid experimental-computational study provides new insights into the thermoelastic-plastic interactions during high speed metal-on-metal slip under extreme interfacial conditions. During the early part of frictional slip the coefficient of kinetic friction is observed to decrease with increasing slip velocity. During the later part transition in interfacial slip occurs from dry metal-on-metal sliding to the formation of molten Al films at the tribo-pair interface. Under these conditions the interfacial resistance approaches the shear strength of the molten aluminum alloy under normal pressures of approximately 1- 3 GPa and shear strain rates of ˜10 7 s-1. The results of the study indicate that under these extreme conditions molten aluminum films maintain a shearing resistance as high as 100 MPa. Scanning electron microscopy of the slip surfaces reveal molten aluminum to be smeared on the tribo-pair interface. Knoop hardness measurements in 7075-T6 Al alloy at various depths from the slip interface indicate that the hardness increases approximately linearly with depth and reaches a plateau at approximately 40 ?m from the surface.

Liou, Nai-Shang; Okada, Makoto; Prakash, Vikas

2004-09-01

215

[Particle release in metal-on-metal bearings. A risk analysis].  

PubMed

Modern metal-on-metal bearings show very low wear rates but release particles and ions from the articulating surfaces into the joint and the whole organism. Especially during the run-in period an increased number of particles is produced. The released metal ions potentially trigger cytotoxic, cancerogenic and allergic reactions, which can impair the patient's health locally or systemically. Many surgeons fear a hypersensitivity reaction to the metal ions of the CoCr alloy in their patients. Today it is assumed that the incidence of these implant-related complications is very low but in some cases it will lead to early failure of the implant. Because the available alternative bearing combinations (ceramic-on-polyethylene and ceramic-on-ceramic) also bear the risk of severe complications, a final statement on the best and safest bearing choice for the patient cannot be made based on the currently existing data. PMID:18551273

Heisel, C; Thomsen, M; Jakubowitz, E; Kretzer, J P

2008-07-01

216

Wear analysis of 39 conserve plus metal-on-metal hip resurfacing retrievals.  

PubMed

There have been increasing concerns regarding adverse local tissue reactions (ALTR) following metal-on-metal (MOM) hip arthroplasties. This study examined wear rates in retrievals of one design of MOM resurfacing arthroplasty, and assessed the differences in wear between those with and without ALTR. Wear measurements were made on 39 MOM resurfacing components (30 femoral, 9 acetabular) which were at least 2years in vivo. Seven hips (6 patients; 4 acetabular components, 7 femoral components) were identified to have ALTR. Acetabular component abduction and anteversion angles were determined using EBRA, and the contact-patch-to-rim (CPR) distance was calculated. The ALTR group had higher linear femoral and acetabular wear rates, acetabular anteversion and abduction angles, lower CPR, and longer time to revision. Given the increased risk for ALTR associated with acetabular component malpositioning, patients with malpositioned acetabular components may require closer clinical follow-up and monitoring. PMID:23845764

Takamura, Karren M; Amstutz, Harlan C; Lu, Zhen; Campbell, Pat A; Ebramzadeh, Edward

2014-02-01

217

Effect of ion implantation on the tribology of metal-on-metal hip prostheses.  

PubMed

Nitrogen ion implantation (which considerably hardens the surface of the bearing) may represent one possible method of reducing the wear of metal-on-metal (MOM) hip bearings. Currently there are no ion-implanted MOM bearings used clinically. Therefore a physiological hip simulator test was undertaken using standard test conditions, and the results compared to previous studies using the same methods. N2-ion implantation of high carbon cast Co-Cr-Mo-on-Co-Cr-Mo hip prostheses increased wear by 2-fold during the aggressive running-in phase compared to untreated bearing surfaces, plus showing no wear reductions during steady-state conditions. Although 2 specimens were considered in the current study, it would appear that ion implantation has no clinical benefit for MOM. PMID:15578563

Bowsher, John G; Hussain, Azad; Williams, Paul; Nevelos, Jim; Shelton, Julia C

2004-12-01

218

Perivascular Lymphocytic Infiltration Is Not Limited to Metal-on-Metal Bearings  

PubMed Central

Background Perivascular lymphocytic infiltration (PVLI) suggests an adaptive immune response. Metal hypersensitivity after THA is presumed associated with idiopathic pain and aseptic loosening, but its incidence and relationship to metallic wear leading to revision are unclear as are its presence and relevance in non-metal-on-metal arthroplasty. Questions/purposes We compared (1) incidence and severity of PVLI in failed hip metal-on-metal (MoM) to non-MoM implants and TKA; (2) PVLI in MoM and non-MoM hip arthroplasty based on reason for revision; and (3) PVLI grade to diffuse lymphocytic infiltration (DLI) and tissue reaction to metal particles. Patients and Methods We retrospectively examined incidence and severity of PVLI, DLI, and tissue reaction in periprosthetic tissue from 215 THA and 242 TKA revisions including 32 MoM hips. Results Perivascular lymphocytic infiltration was present in more TKAs (40%) than overall hip arthroplasties (24%) without difference in severity. Compared to non-MoM hips, MoM bearings were more commonly associated with PVLI (59% versus 18%) and demonstrated increased severity (41% versus 3% greater than mild). Histologically, PVLI correlated (r = 0.51) with DLI, but not tissue reaction. In THA, PVLI was most commonly associated with idiopathic pain (70%) and aseptic loosening (54%) in MoM, and infection in all hip revisions (53%). Conclusions Perivascular lymphocytic infiltration is more extensive in revisions of MoM and in aseptic loosening, idiopathic pain, or infection but is also present in TKA, non-MoM, and different reasons for revision. It correlates with other signs of metal hypersensitivity, but not with histologic measures of metal particulate load. Level of Evidence Level III, diagnostic study. See the Guidelines for Authors for a complete description of levels of evidence.

Ng, Vincent Y.; Berend, Keith R.; Skeels, Michael D.; Adams, Joanne B.

2010-01-01

219

Incidence of pseudotumor and acute lymphocytic vasculitis associated lesion (ALVAL) reactions in metal-on-metal hip articulations: a meta-analysis.  

PubMed

We systematically reviewed the peer-reviewed literature to determine a pooled estimate of the incidence of pseudotumor and acute lymphocytic vasculitis associated lesions (ALVAL) in adult patients with primary metal-on-metal (MoM) total hip arthroplasty or resurfacing. Fourteen eligible articles were identified, with a total of 13,898 MoM hips. The incidence of pseudotumor/ALVAL ranged from 0% to 6.5% of hips with a mean follow-up ranging from 1.7 to 12.3 years across the studies. The pooled estimated incidence of pseudotumor/ALVAL is 0.6% (95% CI: 0.3% to 1.2%). The rate of revision for any reason ranged from 0% to 14.3% of hips, with a pooled estimate of 3.9% (95% CI: 2.7% to 5.3%). PMID:23660012

Wiley, Kevin F; Ding, Kai; Stoner, Julie A; Teague, David C; Yousuf, Khalid M

2013-08-01

220

Transient thermo-mechanical interactions during high-speed slip at metal-on-metal interfaces  

NASA Astrophysics Data System (ADS)

The paper describes results obtained from plate-impact pressure-shear friction experiments to investigate the phenomena of high-speed slip at metal-on-metal interfaces. Using a CH tool-steel/Ti-6Al-4V tribo-pair the authors have studied the effects of normal pressure, slip-speed, temperature and surface roughness on the evolution of the dynamic slip-resistance. Moreover, a finite-element procedure is developed to simulate the evolution of thermo-mechanical fields and understand their relationship to the observed slip response. Next, the pressure-shear friction experiments are extended to investigate the behavior of CH tool-steel/7075-T6 Al alloy tribo-pair. This material combination allows dynamic friction characteristics to be studied in the near-melt and the fully melt temperature regime of the lower-melting-point metal (7075-T6 Al alloy) comprising the tribo-pair. Besides providing information on the slip-velocity versus friction-stress relationship under extreme interfacial conditions, the experiments provides critical information on the shearing resistance of confined molten metal films under high pressures and extremely high shearing rates.

Liou, N. S.; Okada, M.; Irfan, M. A.; Prakash, V.

2003-10-01

221

Wear mechanisms in metal-on-metal bearings: the importance of tribochemical reaction layers.  

PubMed

Metal-on-metal (MoM) bearings are at the forefront in hip resurfacing arthroplasty. Because of their good wear characteristics and design flexibility, MoM bearings are gaining wider acceptance with market share reaching nearly 10% worldwide. However, concerns remain regarding potential detrimental effects of metal particulates and ion release. Growing evidence is emerging that the local cell response is related to the amount of debris generated by these bearing couples. Thus, an urgent clinical need exists to delineate the mechanisms of debris generation to further reduce wear and its adverse effects. In this study, we investigated the microstructural and chemical composition of the tribochemical reaction layers forming at the contacting surfaces of metallic bearings during sliding motion. Using X-ray photoelectron spectroscopy and transmission electron microscopy with coupled energy dispersive X-ray and electron energy loss spectroscopy, we found that the tribolayers are nanocrystalline in structure, and that they incorporate organic material stemming from the synovial fluid. This process, which has been termed "mechanical mixing," changes the bearing surface of the uppermost 50 to 200 nm from pure metallic to an organic composite material. It hinders direct metal contact (thus preventing adhesion) and limits wear. This novel finding of a mechanically mixed zone of nanocrystalline metal and organic constituents provides the basis for understanding particle release and may help in identifying new strategies to reduce MoM wear. PMID:19877285

Wimmer, Markus A; Fischer, Alfons; Büscher, Robin; Pourzal, Robin; Sprecher, Christoph; Hauert, Roland; Jacobs, Joshua J

2010-04-01

222

Wear of metal-on-metal hip bearings: metallurgical considerations after hip simulator studies.  

PubMed

Metal-on-metal hip-bearing components with different percentages of carbon content (low and high carbon) were tested in 6 different configurations using a hip joint simulator. The aim of this study was to characterize metallurgical and tribological events occurring at the articulating surfaces of these articulations. Also, ion release was evaluated and correlated with wear. After the test, for the high-carbon components, carbides were observed below the matrix surface. In the low-carbon content components, most carbides were "carbide-free", while a minority were worn below the matrix surface with increased test cycles. In the cast alloy components, some carbides were pulled out resulting in micropits. Scanning microscope electron characterization of the tested specimens showed scratches and holes. The surface showed a dominant severe wear mechanism due to third-body particles. A greater amount of ions was released in the lubricant used during the wear test for the smaller diameter compared with the bigger one. This study showed that the metallurgical and tribological events taking place at the articulating surfaces of metal-metal hip implants are numerous and complex. The surface morphology after the test showed the effect of more critical working conditions with smaller diameters. PMID:22198601

Affatato, Saverio; Traina, Francesco; Ruggeri, Oddone; Toni, Aldo

2011-12-01

223

Fast growing pseudotumour in a hairdresser after metal-on-metal hip resurfacing: a case report.  

PubMed

A 44-year-old female hairdresser who underwent metal-on-metal hip resurfacing (MOMHR) for hip osteoarthritis developed a benign pelvic pseudotumour. Elevated levels of chromium and cobalt ions were detected in the blood. Patch testing after pseudotumor formation, showed positive skin reactions to cobalt and nickel. Marked hypereosinophilia was noted, as well as the presence of eosinophils in the pseudotumor mass. A revision to a ceramic-on-ceramic implant was performed. Radiographs showed no implant loosening or bone resorption. We hypothesized that a steep cup positioning as well as hypersensitivity response to the metal nanoparticles and ion release may have induced pseudotumour development. Currently there is no evidence that negative patch testing reduces the probability to develop an adverse reaction to metal debris therefore we suggest to carefully investigate patient medical history regarding occupation exposure and daily contact with jewellery, beauty and cleaning products before implanting MOMHR. The main challenge is to identify a sensitive patient candidate to MOMHR never suspected to be. PMID:24825038

Cadossi, M; Chiarello, E; Savarino, L; Mazzotti, A; Tedesco, G; Greco, M; Giannini, S

2014-01-01

224

[MRI investigations in patients with problems due to metal-on-metal implants].  

PubMed

Until recently, metal-on-metal (MoM) hip implants were commonly used for joint replacement and resurfacings. Their use has rapidly declined following reports of Frühversagen and soft tissue disease caused by the release of metal debris from the prosthesis. Detection of these soft tissue lesions has proven difficult using conventional imaging techniques and blood metal ion tests. Current guidelines recommend the use of imaging modalities including metal artefact reduction sequence (MARS) magnetic resonance imaging (MRI), computed tomography and ultrasound but provide little indication which is best. MARS significantly reduces the susceptibility artefact induced by the presence of metal objects, thereby producing diagnostic quality images that can be shared with other physicians and compared over time. The clinical interpretation of MRI findings of solid pseudotumours and severe muscle atrophy is straightforward: revision is usually recommended. However, the most common MRI findings are of a cystic pseudotumour and minor muscle wasting. In these cases decision-making is difficult and we currently use multi-disciplinary and multi-colleague based meetings to make decisions regarding patient management. This article presents a comparison of imaging modalities and an update on the interpretation of MARS MRI for the investigation of patients with MoM hip implants.The English full-text version of this article is available at Springer Link (under "Supplemental"). PMID:23912305

Hart, A

2013-08-01

225

What is a "normal" wear pattern for metal-on-metal hip bearings?  

PubMed

In addition to classical run-in and steady-state wear phases, metal-on-metal (MOM) hip bearings have encountered "runaway wear" (RAW) trends in simulator studies. This puzzling behavior has resulted in 2- to 19-fold wear increases compared with other apparently "identical" bearings. MOM bearings have shown five identifiable RAW wear patterns in joint simulators; therefore, additional descriptive terms were used here to indicate various observed patterns, for example, "breakaway wear" (BAW), which was defined as a higher wear trend that recovers to steady-state wear. As these trends commonly occur for MOM, this raises the question of what can be considered "normal" behavior or "abnormal"? In an effort to identify possible causes for this behavior, the current study investigated six Co-Cr bearings, which closely matched with respect to geometrical tolerances. Despite close control of design and test variables, BAW occurred in 30% of the MOM bearings, producing a threefold wear increase above otherwise identical MOM bearings within the same group. The majority of the BAW (85%) occurred on the cup side and was validated by growth of wear scars and concentrations of metal ions. One bearing that showed continuing BAW at 5 Mc revealed a cup that was 50% smoother than other cups whereas its mating head was 50% rougher, thus signifying that highly polished areas were sites of the highest MOM wear. The two BAW bearings with high wear showed the greatest conformity at 5 Mc, in apparent contradistinction to classical lubrication theory. PMID:19582850

Bowsher, J G; Clarke, I C; Williams, P A; Donaldson, T K

2009-10-01

226

A lexicon for wear of metal-on-metal hip prostheses.  

PubMed

Research on metal-on-metal (MoM) hip bearings has generated an extensive vocabulary to describe the wear processes and resultant surface damage. However, a lack of consistency and some redundancy exist in the current terminology. To facilitate the understanding of MoM tribology and to enhance communication of results among researchers and clinicians, we propose four categories of wear terminology: wear modes refer to the in vivo conditions under which the wear occurred; wear mechanisms refer to fundamental wear processes (adhesion, abrasion, fatigue, and tribochemical reactions); wear damage refers to the resultant changes in the morphology and/or composition of the surfaces; and wear features refer to the specific wear phenomena that are described in terms of the relevant modes, mechanisms, and damage. Clarifying examples are presented, but it is expected that terms will be added to the lexicon as new mechanisms and types of damage are identified. Corrosion refers to electrochemical processes that can remove or add material and thus also generate damage. Corrosion can act alone or may interact with mechanical wear. Examples of corrosion damage are also presented. However, an in-depth discussion of the many types of corrosion and their effects is beyond the scope of the present wear lexicon. © 2014 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 32:1221-1233, 2014. PMID:24844814

McKellop, Harry A; Hart, Alister; Park, Sang-Hyun; Hothi, Harry; Campbell, Pat; Skinner, John A

2014-09-01

227

Wear patterns of taper connections in retrieved large diameter metal-on-metal bearings.  

PubMed

Wear of the modular taper between head and shaft has been related to clinical failure resulting from adverse reactions to metallic debris. The problem has become pronounced in large metal-on-metal bearings, but the mechanism has not yet been fully understood. We analyzed retrieved components from five patients revised with various diagnoses. Two distinct wear patterns were observed for the head tapers. Three samples demonstrated "asymmetric" wear towards the inner end of the head taper. The other two showed "axisymmetric" radial wear (up to 65?µm) presenting the largest wear volumes (up to 20?mm(3)). Stem tapers demonstrated relatively little wear, and the fine thread on the stem taper surface was observed to be imprinted on the taper inside of the head. Our findings demonstrate that the cobalt-chrome head wears preferentially to the titanium stem taper. "asymmetric" wear suggests toggling due to the offset of the joint force vector from the taper. In contrast, samples with "axisymmetric" radial wear and a threaded imprint suggested that corrosion led to head subsidence onto the stem taper with gradual rotation. PMID:23440943

Bishop, Nicholas; Witt, Florian; Pourzal, Robin; Fischer, Alfons; Rütschi, Marcel; Michel, Markus; Morlock, Michael

2013-07-01

228

Revising the well-fixed, painful resurfacing using a double-mobility head: a new strategy to address metal-on-metal complications.  

PubMed

Isolated revision of the femoral component of hip resurfacings to metal-on-metal (MoM) total hip arthroplasties has shown inferior results. We present a case series of well-fixed, painful MoM hips with elevated chromium and cobalt levels. An isolated femoral revision using a noncemented femoral component and a double-mobility head was performed. Patients were followed up for 6 months and showed excellent improvements in visual analog score and Hip dysfunction and Osteoarthritis Outcome Score (HOOS). Cobalt and chromium levels dropped at 6 weeks and were normal at 6 months. Although our follow-up is short, we feel that it is important to highlight this as a potential treatment strategy. This revision is less aggressive than traditional methods, eliminates the concerns from MoM bearings, and results in a stable construct. PMID:22770851

Verhelst, Luk A; Van der Bracht, Hans; Vanhegan, Ivor S; Van Backlé, Bart; De Schepper, Jo

2012-12-01

229

Simple isolation method for the bulk isolation of wear particles from metal on metal bearing surfaces generated in a hip simulator test.  

PubMed

Isolation and characterization of metal-on-metal (MoM) wear particles from simulator lubricants is essential to understand wear behaviour, ion release and associated corrosive activity related to the wear particles. Substantial challenges remain to establish a simple, precise and repeatable protocol for the isolation and analysis of wear particles due to their extremely small size, their tendency to agglomerate and degrade. In this paper, we describe a simple and efficient method for the bulk isolation and characterisation of wear particles from MoM bearings. Freeze drying was used to remove the large volume of water from the serum lubricant, enzymes used to digest the proteins and ultracentrifugation to finally isolate and purify the particles. The present study involved a total of eight steps for the isolation process and a wear particle extraction efficiency of 45% was achieved. PMID:22391991

Lu, Fang; Royle, Matt; Lali, Ferdinand V; Hart, Alister J; Collins, Simon; Housden, Jonathan; Shelton, Julia C

2012-04-01

230

Wear behaviour of cobalt-chromium-molybdenum alloys used in metal-on-metal hip implants  

NASA Astrophysics Data System (ADS)

The influence of carbon (C) content, microstructure, crystallography and mechanical properties on the wear behaviour of metal-on-metal (MM) hip implants made from commercially available cobalt-chromium-molybdenum (CoCrMo) alloys designated as American Society of Testing and Materials (ASTM) grade F1537, F75 and as-cast were studied in this work. The as-received bars of wrought CoCrMo alloys (ASTM F1537 of either about 0.05% or 0.26% C) were each subjected to various heat treatments to develop different microstructures. Pin and plate specimens were fabricated from each bar and were tested against each other using a linear reciprocating pin-on-plate apparatus in 25% by volume bovine serum solution. The applied normal load was 9.81 N and the reciprocating plate had a sinusoidal velocity with an average speed of 26 mm/s. The wear was measured gravimetrically and it was found to be most strongly affected by alloy C content, irrespective of grain size or carbide morphology. More precisely, the wear behaviour was directly correlated to the dissolved C content of the alloys. Increased C in solid-solution coincided with lower volumetric wear since C helps to stabilize the face-centred cubic (FCC) crystal structure thus limiting the amount of strain induced transformation (SIT) to the hexagonal close-packed crystal structure (HCP). Based on the observed surface twinning in and around the contact zone and the potentially detrimental effect of the HCP phase, it was postulated that the MM wear behaviour of CoCrMo alloys in the present study was controlled by a deformation mechanism, rather than corrosion or tribochemical reactions.

Varano, Rocco

231

Necrotic and inflammatory changes in metal-on-metal resurfacing hip arthroplasties  

PubMed Central

Background Necrosis and inflammation in peri-implant soft tissues have been described in failed second-generation metal-on-metal (MoM) resurfacing hip arthroplasties and in the pseudotumors associated with these implants. The precise frequency and significance of these tissue changes is unknown. Method We analyzed morphological and immunophenotypic changes in the periprosthetic soft tissues and femoral heads of 52 revised MoM arthroplasties (fracture in 21, pseudotumor in 13, component loosening in 9, and other causes in 9 cases). Results Substantial necrosis was observed in the periprosthetic connective tissue in 28 of the cases, including all pseudotumors, and 5 cases of component loosening. A heavy, diffuse inflammatory cell infiltrate composed mainly of HLA-DR+/CD14+/CD68+ macrophages and CD3+ T cells was seen in 45 of the cases. Perivascular lymphoid aggregates composed of CD3+ cells and CD20+ B cells were noted in 27 of the cases, but they were not seen in all cases of component loosening or pseudotumors. Plasma cells were noted in 30 cases. Macrophage granulomas were noted in 6 cases of component loosening. In the bone marrow of the femoral head, a macrophage and T cell response was seen in 31 of the cases; lymphoid aggregates were noted in 19 of the cases and discrete granulomas in 1 case. Interpretation Our findings indicate that there is a spectrum of necrotic and inflammatory changes in response to the deposition of cobalt-chrome (Co-Cr) wear particles in periprosthetic tissues. Areas of extensive coagulative necrosis and a macrophage and T lymphocyte response occur in implant failure and pseudotumors, in which there is also granuloma formation. The pathogenesis of these changes is uncertain but it may involve both a cytotoxic response and a delayed hypersensitivity (type IV) response to Co-Cr particles.

2009-01-01

232

Changes in blood ion levels after removal of metal-on-metal hip replacements.  

PubMed

Background and purpose - In patients with metal-on-metal (MoM) hip prostheses, pain and joint effusions may be associated with elevated blood levels of cobalt and chromium ions. Since little is known about the kinetics of metal ion clearance from the body and the rate of resolution of elevated blood ion levels, we examined the time course of cobalt and chromium ion levels after revision of MoM hip replacements. Patients and methods - We included 16 patients (13 female) who underwent revision of a painful MoM hip (large diameter, modern bearing) without fracture or infection, and who had a minimum of 4 blood metal ion measurements over an average period of 6.1 (0-12) months after revision. Results - Average blood ion concentrations at the time of revision were 22 ppb for chromium and 43 ppb for cobalt. The change in ion levels after revision surgery varied extensively between patients. In many cases, over the second and third months after revision surgery ion levels decreased to 50% of the values measured at revision. Decay of chromium levels occurred more slowly than decay of cobalt levels, with a 9% lag in return to normal levels. The rate of decay of both metals followed second-order (exponential) kinetics more closely than first-order (linear) kinetics. Interpretation - The elimination of cobalt and chromium from the blood of patients who have undergone revision of painful MoM hip arthroplasties follows an exponential decay curve with a half-life of approximately 50 days. Elevated blood levels of cobalt and chromium ions can persist for at least 1 year after revision, especially in patients with high levels of exposure. PMID:24758321

Durrani, Salim K; Noble, Philip C; Sampson, Barry; Panetta, Therese; Liddle, Alexander D; Sabah, Shiraz A; Chan, Newton K; Skinner, John A; Hart, Alister J

2014-06-01

233

Changes in blood ion levels after removal of metal-on-metal hip replacements  

PubMed Central

Background and purpose In patients with metal-on-metal (MoM) hip prostheses, pain and joint effusions may be associated with elevated blood levels of cobalt and chromium ions. Since little is known about the kinetics of metal ion clearance from the body and the rate of resolution of elevated blood ion levels, we examined the time course of cobalt and chromium ion levels after revision of MoM hip replacements. Patients and methods We included 16 patients (13 female) who underwent revision of a painful MoM hip (large diameter, modern bearing) without fracture or infection, and who had a minimum of 4 blood metal ion measurements over an average period of 6.1 (0–12) months after revision. Results Average blood ion concentrations at the time of revision were 22 ppb for chromium and 43 ppb for cobalt. The change in ion levels after revision surgery varied extensively between patients. In many cases, over the second and third months after revision surgery ion levels decreased to 50% of the values measured at revision. Decay of chromium levels occurred more slowly than decay of cobalt levels, with a 9% lag in return to normal levels. The rate of decay of both metals followed second-order (exponential) kinetics more closely than first-order (linear) kinetics. Interpretation The elimination of cobalt and chromium from the blood of patients who have undergone revision of painful MoM hip arthroplasties follows an exponential decay curve with a half-life of approximately 50 days. Elevated blood levels of cobalt and chromium ions can persist for at least 1 year after revision, especially in patients with high levels of exposure.

Durrani, Salim K; Sampson, Barry; Panetta, Therese; Liddle, Alexander D; Sabah, Shiraz A; Chan, Newton K; Skinner, John A; Hart, Alister J

2014-01-01

234

Metal presence in hair after metal-on-metal resurfacing arthroplasty.  

PubMed

The elevation of metal levels in serum and urine during post-operative follow-up is a frequent find following the implantation of certain models of metal-on-metal hip prostheses. Among 45 patients with the same resurfacing prostheses, chromium (Cr) and cobalt (Co) levels in serum and urine were determined at 3, 4, 5, and 6 years after surgery. In the same period, levels of Cr, Co and molibdene (Mo) in scalp hair were also measured. Mean Cr and Co levels in serum were 8.29 µg/L (SD 17.97) and 8.38 µg/L (SD 21.97), respectively, whereas in urine levels were 16.20 µg/L (SD SD 32.55) and 75.40 µg/L (SD 190.86), respectively. In hair, mean Cr level were 163.27 µg/g (SD 300.62), mean Co level 61.98 µg/g (SD 126.48), and Mo 31.36 µg/g (SD 37.86). A high concordance was observed between chromium-urine and chromium-serum and between cobalt-urine and cobalt-hair. A moderate concordance was present between cobalt-urine and cobalt-serum, and between cobalt-hair and cobalt-serum. Eleven patients required revision surgery, five of them due to metallosis and periarticular cyst. At 1 year after reintervention, analytics were performed again and the following decrease rates were found: 42.8% in Cr levels, 51.1% in Mo levels, and 90.3% in Co levels. PMID:23893786

Rodríguez de la Flor, María; Hernández-Vaquero, Daniel; Fernández-Carreira, José Manuel

2013-12-01

235

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

NASA Astrophysics Data System (ADS)

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.

Hart, Alister J.; Sandison, Ann; Quinn, Paul; Sampson, Barry; Atkinson, Kirk D.; Skinner, John A.; Goode, Angela; Powell, Jonathan J.; Mosselmans, J. Frederick W.

2009-11-01

236

The relationship between the presence of metallosis and massive infection in metal-on-metal hip replacements.  

PubMed

With the increased use of metal-on-metal as a bearing surface, complications and side effects are being recognised more frequently. We present a small series of a previously unreported complication, which appears specific to metal-on-metal bearing surface arthroplasties: three cases of infection in the presence of local metal debris and histological features of aseptic lymphocytic vasculitis associated lesions (ALVAL). Each case is associated with significant soft tissue loss and bone destruction to such an extent that pelvic discontinuity has occurred. We postulate that the combination of metal debris, ALVAL and tissue necrosis provides a unique environment for peri-prosthetic bacterial growth and rapid spread of infection. PMID:20544666

Donaldson, James R; Miles, Jonathan; Sri-Ram, Kesavan; Poullis, Christopher; Muirhead-Allwood, Sarah; Skinner, John

2010-01-01

237

The chemical form of metallic debris in tissues surrounding metal-on-metal hips with unexplained failure  

Microsoft Academic Search

Implant-derived material from metal-on-metal (MOM) hip arthroplasties may be responsible for an unexplained tissue inflammatory response. The chemical form of the metal species in the tissues is predominantly chromium (Cr), but the currently used techniques have not been able to determine whether this is Cr(III) phosphate or Cr(III) oxide. The analytical challenge must overcome the fact that the metal in

Alister J. Hart; Paul D. Quinn; Barry Sampson; Ann Sandison; Kirk D. Atkinson; John A. Skinner; Jonathan J. Powell; J. Fred W. Mosselmans

2010-01-01

238

Effect of bearing geometry and structure support on transient elastohydrodynamic lubrication of metal-on-metal hip implants  

Microsoft Academic Search

An effective lubrication can significantly reduce wear of metal-on-metal artificial hip joints. The improvement of the lubrication can be achieved through the optimisation of the bearing geometry in terms of a small clearance and\\/or the structural support such as a polyethylene backing underneath a metallic bearing in a sandwich acetabular cup form. The separate effects of these two factors on

Feng Liu; Zhongming Jin; Paul Roberts; Peter Grigoris

2007-01-01

239

Metal ion release from bearing wear and corrosion with 28 mm and large-diameter metal-on-metal bearing articulations: a follow-up study.  

PubMed

We have updated our previous randomised controlled trial comparing release of chromium (Cr) and cobalt (Co) ions and included levels of titanium (Ti) ions. We have compared the findings from 28 mm metal-on-metal total hip replacement, performed using titanium CLS/Spotorno femoral components and titanium AlloFit acetabular components with Metasul bearings, with Durom hip resurfacing using a Metasul articulation or bearing and a titanium plasma-sprayed coating for fixation of the acetabular component. Although significantly higher blood ion levels of Cr and Co were observed at three months in the resurfaced group than in total hip replacement, no significant difference was found at two years post-operatively for Cr, 1.58 microg/L and 1.62 microg/L respectively (p = 0.819) and for Co, 0.67 microg/L and 0.94 microg/L respectively (p = 0.207). A steady state was reached at one year in the resurfaced group and after three months in the total hip replacement group. Interestingly, Ti, which is not part of the bearing surfaces with its release resulting from metal corrosion, had significantly elevated ion levels after implantation in both groups. The hip resurfacing group had significantly higher Ti levels than the total hip replacement group for all periods of follow-up. At two years the mean blood levels of Ti ions were 1.87 microg/L in hip resurfacing and and 1.30 microg/L in total hip replacement (p = 0.001). The study confirms even with different bearing diameters and clearances, hip replacement and 28 mm metal-on-metal total hip replacement produced similar Cr and Co metal ion levels in this randomised controlled trial study design, but apart from wear on bearing surfaces, passive corrosion of exposed metallic surfaces is a factor which influences ion concentrations. Ti plasma spray coating the acetabular components for hip resurfacing produces significantly higher release of Ti than Ti grit-blasted surfaces in total hip replacement. PMID:20044673

Vendittoli, P-A; Roy, A; Mottard, S; Girard, J; Lusignan, D; Lavigne, M

2010-01-01

240

Blood metal ion testing is an effective screening tool to identify poorly performing metal-on-metal bearing surfaces  

PubMed Central

Objectives The aims of this piece of work were to: 1) record the background concentrations of blood chromium (Cr) and cobalt (Co) concentrations in a large group of subjects; 2) to compare blood/serum Cr and Co concentrations with retrieved metal-on-metal (MoM) hip resurfacings; 3) to examine the distribution of Co and Cr in the serum and whole blood of patients with MoM hip arthroplasties; and 4) to further understand the partitioning of metal ions between the serum and whole blood fractions. Methods A total of 3042 blood samples donated to the local transfusion centre were analysed to record Co and Cr concentrations. Also, 91 hip resurfacing devices from patients who had given pre-revision blood/serum samples for metal ion analysis underwent volumetric wear assessment using a coordinate measuring machine. Linear regression analysis was carried out and receiver operating characteristic curves were constructed to assess the reliability of metal ions to identify abnormally wearing implants. The relationship between serum and whole blood concentrations of Cr and Co in 1048 patients was analysed using Bland-Altman charts. This relationship was further investigated in an in vitro study during which human blood was spiked with trivalent and hexavalent Cr, the serum then separated and the fractions analysed. Results Only one patient in the transfusion group was found to have a blood Co > 2 µg/l. Blood/Serum Cr and Co concentrations were reliable indicators of abnormal wear. Blood Co appeared to be the most useful clinical test, with a concentration of 4.5 µg/l showing sensitivity and specificity for the detection of abnormal wear of 94% and 95%, respectively. Generated metal ions tended to fill the serum compartment preferentially in vivo and this was replicated in the in vitro study when blood was spiked with trivalent Cr and bivalent Co. Conclusions Blood/serum metal ion concentrations are reliable indicators of abnormal wear processes. Important differences exist however between elements and the blood fraction under study. Future guidelines must take these differences into account.

Sidaginamale, R. P.; Joyce, T. J.; Lord, J. K.; Jefferson, R.; Blain, P. G.; Nargol, A. V. F.; Langton, D. J.

2013-01-01

241

Survivorship of standard versus modified posterior surgical approaches in metal-on-metal hip resurfacing  

PubMed Central

Objectives Metal-on-metal hip resurfacing (MOMHR) is available as an alternative option for younger, more active patients. There are failure modes that are unique to MOMHR, which include loosening of the femoral head and fractures of the femoral neck. Previous studies have speculated that changes in the vascularity of the femoral head may contribute to these failure modes. This study compares the survivorship between the standard posterior approach (SPA) and modified posterior approach (MPA) in MOMHR. Methods A retrospective clinical outcomes study was performed examining 351 hips (279 male, 72 female) replaced with Birmingham Hip Resurfacing (BHR, Smith and Nephew, Memphis, Tennessee) in 313 patients with a pre-operative diagnosis of osteoarthritis. The mean follow-up period for the SPA group was 2.8 years (0.1 to 6.1) and for the MPA, 2.2 years (0.03 to 5.2); this difference in follow-up period was statistically significant (p < 0.01). Survival analysis was completed using the Kaplan–Meier method. Results At four years, the Kaplan–Meier survival curve for the SPA was 97.2% and 99.4% for the MPA; this was statistically significant (log-rank; p = 0.036). There were eight failures in the SPA and two in the MPA. There was a 3.5% incidence of femoral head collapse or loosening in the SPA and 0.4% in the MPA, which represented a significant difference (p = 0.041). There was a 1.7% incidence of fractures of the femoral neck in the SPA and none in the MPA (p = 0.108). Conclusion This study found a significant difference in survivorship at four years between the SPA and the MPA (p = 0.036). The clinical outcomes of this study suggest that preserving the vascularity of the femoral neck by using the MPA results in fewer vascular-related failures in MOMHRs. Cite this article: Bone Joint Res 2014;3:150–4

M. Takamura, K.; Maher, P.; Nath, T.; Su, E. P.

2014-01-01

242

Longitudinal evaluation of time related femoral neck narrowing after metal-on-metal hip resurfacing  

PubMed Central

AIM: To track the short-term neck narrowing changes in Birmingham metal-on-metal hip resurfacing (MOMHR) patients. METHODS: Since 2001, the Center for Hip and Knee Replacement started a registry to prospectively collect data on hip and knee replacement patients. From June 2006 to October 2008, 139 MOMHR were performed at our center by two participate surgeons using Birmingham MOMHR prosthesis (Smith Nephew, United States). It is standard of care for patients to obtain low, anteriorposterior (LAP) pelvis radiographs immediately after MOMHR procedure and then at 3 mo, 1 year and 2 year follow up office visits. Inclusion criteria for the present study included patients who came back for follow up office visit at above mentioned time points and got LAP radiographs. Exclusion criteria include patients who missed more than two follow up time points and those with poor-quality X-rays. Two orthopaedic residency trained research fellows reviewed the X-rays independently at 4 time points, i.e., immediate after surgery, 3 mo, 1 year and 2 year. Neck-to-prosthesis ratio (NPR) was used as main outcome measure. Twenty cases were used as subjects to identify the reliability between two observers. An intraclass correlation coefficient at 0.8 was considered as satisfied. A paired t-test was used to evaluate the significant difference between different time points with P < 0.05 considered to be statistically significant. RESULTS: The mean NPRs were 0.852 ± 0.056, 0.839 ± 0.052, 0.835 ± 0.051, 0.83 ± 0.04 immediately, 3 mo, 1 year and 2 years post-operatively respectively. At 3 mo, NPR was significantly different from immediate postoperative X-ray (P < 0.001). There was no difference between 3 mo and 1 year (P = 0.14) and 2 years (P = 0.53). Femoral neck narrowing (FNN) exceeding 10% of the diameter of the neck was observed in only 4 patients (5.6%) at two years follow up. None of these patients developed a femoral neck fracture (FNF). CONCLUSION: Femoral neck narrowing after MOMHR occurred as early as 3 mo postoperatively, and stabilized thereafter. Excessive FNN was not common in patients within the first two years of surgery and was not correlated with risk of FNF.

Wang, Wenbao; Geller, Jeffrey A; Hasija, Rohit; Choi, Jung Keun; Patrick, David A Jr.; Macaulay, William

2013-01-01

243

Grading the severity of soft tissue changes associated with metal-on-metal hip replacements: reliability of an MR grading system  

Microsoft Academic Search

Introduction  Metal-on-metal (MoM) soft tissue reactions or aseptic lymphocytic vasculitis-associated lesions (ALVAL) are being recognised\\u000a using metal artefact reduction (MAR) MR with increasing frequency following the advent of second generation metal-on-metal\\u000a bearings, but there is no standardised technique for reporting of MR appearances in this disease. The aim of this study was\\u000a to measure the reliability of a grading system designed

Helen Anderson; Andoni Paul Toms; John G. Cahir; Richard W. Goodwin; James Wimhurst; John F. Nolan

2011-01-01

244

Effect of simplifications of bone and components inclination on the elastohydrodynamic lubrication modeling of metal-on-metal hip resurfacing prosthesis.  

PubMed

It is important to study the lubrication mechanism of metal-on-metal hip resurfacing prosthesis in order to understand its overall tribological performance, thereby minimize the wear particles. Previous elastohydrodynamic lubrication studies of metal-on-metal hip resurfacing prosthesis neglected the effects of the orientations of the cup and head. Simplified pelvic and femoral bone models were also adopted for the previous studies. These simplifications may lead to unrealistic predictions. For the first time, an elastohydrodynamic lubrication model was developed and solved for a full metal-on-metal hip resurfacing arthroplasty. The effects of the orientations of components and the realistic bones on the lubrication performance of metal-on-metal hip resurfacing prosthesis were investigated by comparing the full model with simplified models. It was found that the orientation of the head played a very important role in the prediction of pressure distributions and film profiles of the metal-on-metal hip resurfacing prosthesis. The inclination of the hemispherical cup up to 45° had no appreciable effect on the lubrication performance of the metal-on-metal hip resurfacing prosthesis. Moreover, the combined effect of material properties and structures of bones was negligible. Future studies should focus on higher inclination angles, smaller coverage angle and microseparation related to the occurrences of edge loading. PMID:23637262

Meng, Qingen; Liu, Feng; Fisher, John; Jin, Zhongmin

2013-05-01

245

Effect of Corrosion and Biofilm on Friction Behavior in Biotribocorrosion System for Metal-on-Metal Hip Prosthesis  

Microsoft Academic Search

\\u000a The second generation Metal-on-Metal (MoM) hip replacements have been considered as an alternative to commonly used Polyethylene-on-Metal\\u000a (PoM) joint prosthesis due to polyethylene wear debris induced osteolysis. However, the role of corrosion and the biofilm\\u000a formed under tribological contact are still not fully understood. Bench tests have been carried out to characterize the relationship\\u000a and interactions between electrochemical reactions (corrosion),

Yu Yan; Duncan Dowson; Sophie Williams; Anne Neville; John Fisher

246

Contact mechanics of metal-on-metal hip implants employing a metallic cup with a UHMWPE backing.  

PubMed

The contact mechanics in metal-on-metal hip implants employing a cobalt chromium acetabular cup with an ultra-high molecular weight polyethylene (UHMWPE) backing were analysed in the present study using the finite element method. A general modelling methodology was developed to examine the effects of the interfacial boundary conditions between the UHMWPE backing and a titanium shell for cementless fixation, the coefficient of friction and the loading angle on the predicted contact pressure distribution at the articulating surfaces. It was found that the contact mechanics at the bearing surfaces were significantly affected by the UHMWPE backing. Consequently, a relatively constant pressure distribution was predicted within the contact conjunction, and the maximum contact pressure occurred towards the edge of the contact. On the other hand, the interfacial boundary condition between the UHMWPE backing and the titanium shell, the coefficient of friction and the loading angle were found to have a negligible effect on the contact mechanics at the bearing surfaces. Overall, the magnitude of the contact pressure was significantly reduced, compared with a similar cup without the UHMWPE backing. The importance of the UHMWPE backing on the tribological performance of metal-on-metal hip implants is discussed. PMID:12807161

Liu, F; Jin, Z M; Grigoris, P; Hirt, F; Rieker, C

2003-01-01

247

Contact mechanics and elastohydrodynamic lubrication in a novel metal-on-metal hip implant with an aspherical bearing surface.  

PubMed

Diameter and diametral clearance of the bearing surfaces of metal-on-metal hip implants and structural supports have been recognised as key factors to reduce the dry contact and hydrodynamic pressures and improve lubrication performance. On the other hand, application of aspherical bearing surfaces can also significantly affect the contact mechanics and lubrication performance by changing the radius of the curvature of a bearing surface and consequently improving the conformity between the head and the cup. In this study, a novel metal-on-metal hip implant employing a specific aspherical bearing surface, Alpharabola, as the acetabular surface was investigated for both contact mechanics and elastohydrodynamic lubrication under steady-state conditions. When compared with conventional spherical bearing surfaces, a more uniform pressure distribution and a thicker lubricant film thickness within the loaded conjunction were predicted for this novel Alpharabola hip implant. The effects of the geometric parameters of this novel acetabular surface on the pressure distribution and lubricant thickness were investigated. A significant increase in the predicted lubricant film thickness and a significant decrease in the dry contact and hydrodynamic pressures were found with appropriate combinations of these geometric parameters, compared with the spherical bearing surface. PMID:20003978

Meng, Qingen; Gao, Leiming; Liu, Feng; Yang, Peiran; Fisher, John; Jin, Zhongmin

2010-03-22

248

Effect of head size on wear properties of metal-on-metal bearings of hip prostheses, and comparison with wear properties of metal-on-polyethylene bearings using hip simulator.  

PubMed

The effects of articular head size on the wear losses of the metal insert and articular head for a metal-on-metal bearing were examined using a hip simulator manufactured to satisfy ISO 14242-1. The wear properties of metal-on-metal and metal-on-polyethylene bearings were also compared under the same conditions. The total wear losses of the metal insert and articular head decreased with increasing diameter of the metal insert in the range from 28 to 44mm. The total wear loss was greater for a diameter of 48mm than for a diameter of 44mm. When the articular metal insert diameter was smaller than 44mm, the wear loss was reduced because the contact surface pressure increased with increasing metal insert diameter. However, the increase in wear loss observed for the 48-mm-diameter insert might have been due to the considerable increase in the rotation moment with increasing insert diameter. The tendency of decreasing contact pressure calculated using the Hertzian contact stress equation nearly conformed to the change in wear loss. On the other hand, the wear loss of an artificial hip joint consisting of a cross-linked ultrahigh-molecular-weight polyethylene insert (UHMWPE) and a Co-Cr-Mo articular head was small. PMID:24290355

Okazaki, Yoshimitsu

2014-03-01

249

Electrochemical instrumentation of a hip simulator: a new tool for assessing the role of corrosion in metal-on-metal hip joints.  

PubMed

Polyethylene wear debris induced osteolysis has triggered investigations to find alternative material combinations to the well-established metal-on-polyethylene hip implants. Owing to some early successful clinical cases, metal-on-metal (MoM) hip replacements have been attracting more and more interest. There is, however, considerable concern about the propensity of MoM hip replacements to release metal ions and fine, nanometre-scale metallic wear debris. The long-term effect from released metal ions and wear particles is still not clear. To date, all the work on hip simulators focused on assessing mass losses damage has been referred to as 'wear'. However, it is known in the field of tribocorrosion that mechanical removal of the passive layer on Co-Cr alloys can significantly enhance corrosion activity. In total joint replacements, it is possible that corrosion plays a significant role. However, no one has ever tried to extract, on a hip simulator, what proportion of the damage is due to mechanical processes and the corrosion processes. This paper describes the first instrumentation of an integrated hip joint simulator to provide in-situ electrochemical measurements in real time. The open circuit potential results are reported to assess the corrosion regime in the absence and presence of movement at the bearing surfaces. The importance of these measurements is that the real damage mechanisms can be assessed as a function of the operating cycle. PMID:21218689

Yan, Y; Neville, A; Dowson, D; Williams, S; Fisher, J

2010-11-01

250

A safe zone for acetabular component position in metal-on-metal hip resurfacing arthroplasty: winner of the 2012 HAP PAUL award.  

PubMed

A safe zone for acetabular component positioning in hip resurfacing (RAIL: Relative Acetabular Inclination Limit) was calculated based on implant size and acetabular inclination angle (AIA). For AIA below the RAIL, there were no adverse wear failures or dislocations, and only 1% of cases with ion levels above 10 ?g/L. Other than high inclination angle and small bearing size, female gender was the only other factor that correlated with high ion levels in the multivariate analysis. Seven hundred sixty-one hip resurfacing cases are included in this study. The UCLA activity score, femoral shaft angle, body mass index, weight, American Society of Anesthesiologists score, combined range of motion, diagnosis, age, gender, implant brand, AIA, bearing size, and duration of implantation were analyzed to determine the potential risk factors for elevated metal ion levels. These findings apply to sub hemispheric metal-on-metal bearings with similar coverage arcs as the Biomet and Corin hip resurfacing brands. Additional problems may occur when these bearings are connected with trunions on stems for total hip arthroplasty. PMID:23540536

Liu, Fei; Gross, Thomas P

2013-08-01

251

Metal ion levels and functional results after either resurfacing hip arthroplasty or conventional metal-on-metal hip arthroplasty  

PubMed Central

Background Modern metal-on-metal hip resurfacing was introduced as a bone-preserving method of joint reconstruction for young and active patients; however, the large diameter of the bearing surfaces is of concern for potentially increased metal ion release. Patients and methods 71 patients (< 65 years old) were randomly assigned to receive either a resurfacing (R) hip arthroplasty (n = 38) or a conventional metal-on-metal (C) hip arthroplasty (n = 33). Functional outcomes were assessed preoperatively and at 6, 12, and 24 months. Cobalt and chromium blood levels were analyzed preoperatively and at 3, 6, 12, and 24 months. Results All functional outcome scores improved for both groups. At 12 and 24 months, the median UCLA activity score was 8 in the R patients and 7 in the C patients (p < 0.05). At 24 months, OHS was median 16 in C patients and 13 in R patients (p < 0.05). However, in spite of randomization, UCLA scores also appeared to be higher in R patients at baseline. Satisfaction was similar in both groups at 24 months. Cobalt concentrations were statistically significantly higher for R patients only at 3 and 6 months. Chromium levels remained significantly higher for R patients until 24 months. No pseudotumors were encountered in either group. One R patient was revised for early aseptic loosening and in 2 C patients a cup insert was exchanged for recurrent dislocation. Interpretation R patients scored higher on UCLA, OHS, and satisfaction at some time points; however, as for the UCLA, preoperative levels were already in favor of R. The differences, although statistically significant, were of minor clinical importance. Chromium blood levels were statistically significantly higher for R patients at all follow-up measurements, whereas for cobalt this was only observed up to 6 months. The true value of resurfacing hip arthroplasty over conventional metal-on-metal hip arthroplasty will be determined by longer follow-up and a possible shift of balance between their respective (dis)advantages.

2011-01-01

252

Treatment of pseudotumors after metal-on-metal hip resurfacing based on magnetic resonance imaging, metal ion levels and symptoms.  

PubMed

Peri-prosthetic pseudotumor formation can be a severe complication following Metal-on-Metal hip resurfacing arthroplasty (MoMHRA), with limited data on the optimal management of this complication. The aims of this study were (1) to evaluate the prevalence and severity of pseudotumors in a consecutive cohort of 248 MoMHRA (214 patients, mean follow-up 4.6 years, range: 1 - 8.2), and (2) to present a clinical guideline for their treatment based on severity grading with Metal Artefact Reduction Sequence Magnetic Resonance Imaging, metal ion levels and symptoms. Pseudotumor prevalence was 36.3%: 61 mild, 25 moderate and four were graded severe. Five revisions followed, all in symptomatic patients with elevated metal ion levels. Pseudotumor severity grading allowed us to be conservative with revision surgery for mild and moderate MoM disease. PMID:23871706

van der Weegen, Walter; Sijbesma, Thea; Hoekstra, Henk J; Brakel, Koen; Pilot, Peter; Nelissen, Rob G H H

2014-02-01

253

A HIERARCHY OF COMPUTATIONALLY DERIVED SURGICAL AND PATIENT INFLUENCES ON METAL ON METAL PRESS-FIT ACETABULAR CUP FAILURE  

PubMed Central

The impact of anatomical variation and surgical error on excessive wear and loosening of the acetabular component of large diameter metal on metal hip arthroplasties was measured using a multi-factorial analysis through 112 different simulations. Each surgical scenario was subject to eight different daily loading activities using finite element analysis. Excessive wear appears to be predominantly dependent on cup orientation, with inclination error having a higher influence than version error, according to the study findings. Acetabular cup loosening, as inferred from initial implant stability, appears to depend predominantly on factors concerning the area of cup-bone contact, specifically the level of cup seating achieved and the individual patient’s anatomy. The extent of press fit obtained at time of surgery did not appear to influence either mechanism of failure in this study.

Clarke, S G; Phillips, A T M; Bull, A M J; Cobb, J P

2014-01-01

254

Revision of metal-on-metal resurfacing arthroplasty of the hip: the influence of malpositioning of the components.  

PubMed

We have reviewed 42 patients who had revision of metal-on-metal resurfacing procedures, mostly because of problems with the acetabular component. The revisions were carried out a mean of 26.2 months (1 to 76) after the initial operation and most of the patients (30) were female. Malpositioning of the acetabular component resulted in 27 revisions, mostly because of excessive abduction (mean 69.9 degrees ; 56 degrees to 98 degrees ) or insufficient or excessive anteversion. Seven patients had more than one reason for revision. The mean increase in the diameter of the component was 1.8 mm (0 to 4) when exchange was needed. Malpositioning of the components was associated with metallosis and a high level of serum ions. The results of revision of the femoral component to a component with a modular head were excellent, but four patients had dislocation after revision and four required a further revision. PMID:18757954

De Haan, R; Campbell, P A; Su, E P; De Smet, K A

2008-09-01

255

Metal ion levels not sufficient as a screening measure for adverse reactions in metal-on-metal hip arthroplasties.  

PubMed

This study aims to assess the accuracy of metal ion analysis in the diagnosis of adverse reaction to metal debris (ARMD) in patients with metal-on-metal hip arthroplasties by comparing the cobalt and chromium levels in 57 patients (62 hips) to findings on metal artifact reduction magnetic resonance imaging (MRI). An ARMD was detected using MRI in 18 (29%) of the hips. Forty patients had cobalt levels less than 7 ?g/L, and 33 had chromium levels less than 7 ?g/L, but 8 of these had an ARMD on MRI and only minimal symptoms (Oxford Hip Score ? 44/48). The incidence of ARMD was significantly higher when chromium concentration was above 7 ?g/L (P = .02), but normal metal ion levels can be misleading and metal artifact reduction MRI imaging is advised in all patients. PMID:22771092

Macnair, Rory D; Wynn-Jones, Henry; Wimhurst, James A; Toms, Andoni; Cahir, John

2013-01-01

256

A comparative study on medium-term results of cementless acetabular components with metal-on-metal and metal-on-polyethylene articulations  

Microsoft Academic Search

The purpose of this study was to evaluate the medium-term clinical and radiological outcomes of two metal-backed acetabular\\u000a cups with metal-on-metal and metal-on-polyethylene joint couples, in patients unselected for age. Seventy-five metal-on-polyethylene\\u000a CLS expansion cups were implanted in 70 patients and 66 metal-on-metal Fitek cups were implanted in 65 patients. The average\\u000a age at surgery in the two groups was

F. Cozzolino; M. Mariconda; L. Costa; D. Scognamiglio; A. Cozzolino; D. Marinò; C. Milano

2002-01-01

257

Metal-on-metal hip implants: do they impair renal function in the long-term? A 10-year follow-up study  

Microsoft Academic Search

Introduction  The aim of our study was to investigate a potential influence of elevated serumcobalt and serumchromiumlevels on renal function\\u000a at minimum 10 years after implantation of a metal-on-metal hip.\\u000a \\u000a \\u000a \\u000a Materials and methods  Between November 1992 and June 1994 98 patients (44 m, 54 f) with an average age of 56 (22–79) years received a metal-on-metal\\u000a bearing Metasul™. At the time of the 10-year follow-up,

Martina Marker; Alexander Grübl; Otto Riedl; Georg Heinze; Erich Pohanka; Rainer Kotz

2008-01-01

258

Radiographic Evaluation of Midterm Failure Rates Following Metal-on-Metal Hip Resurfacing  

Microsoft Academic Search

This prospective study examined patient characteristics and radiographic findings for 89 subjects undergoing total hip resurfacing. Thirteen (14.6%) of 89 hips have required revision. Female sex, smaller implant size, and diagnosis of osteonecrosis were associated with lower device survival. No significant differences in acetabular cup angle and stem angle were observed between revised and nonrevised hips. Revision rates for the

Lucas S. Rylander; Joseph C. Milbrandt; Adam B. Wallace; D. Gordon Allan

2011-01-01

259

Island growth in ion beam assisted metal-on-metal deposition modelled by rate equations  

NASA Astrophysics Data System (ADS)

Island growth in ion beam assisted deposition (IBAD) is modelled by rate equations, where deposition, diffusion driven aggregation, defect and target adatom production and island fragmentation are taken into account. It is shown that compared with results obtained for a thermal deposition, deposition with ion bombardment induced island fragmentation causes the total island density to increase and average island size to decrease. The observed behaviour is in qualitative agreement with experimental findings. It is demonstrated how the appropriately scaled island size distributions depend crucially on the fragmentation process, but remain relatively unaffected by diffusion. Possibilities to use scaled distributions in recognizing experimentally the relative importance of different processes in IBAD are pointed out.

Sillanpää, Jussi; Koponen, Ismo

1998-06-01

260

Early failure of the Durom prosthesis in metal-on-metal hip resurfacing in Chinese patients.  

PubMed

Hip resurfacing (HR) is being used increasingly as an alterative to total hip arthroplasty in osteonecrosis (ON) and ankylosing spondylitis (AS) of the hip. We performed 141 consecutive HR arthroplasties in 111 patients comprising 3 etiology groups: ON, AS, and osteoarthritis (OA). After retrospective study of retrieved components, we hypothesized that the main reason for revision was femoral loosening in the ON group (4 of 46 hips; 8.7%) and femoral-neck fracture in the AS group (3 of 58 hips; 5.2%). Necrotic areas were seen on femoral heads retrieved from patients with femoral loosening, whereas femoral heads were fixed tightly to components in patients with femoral-neck fractures. Etiology may be an important risk factor for postoperative complications. PMID:23831082

Li, Jia; He, Chongru; Li, Dahe; Zheng, Wei; Liu, Denghui; Xu, Weidong

2013-12-01

261

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

Microsoft Academic Search

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

Bernhard Tins

2010-01-01

262

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

Microsoft Academic Search

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

Bernhard Tins

2011-01-01

263

Bone mineral density of the proximal femur recovers after metal-on-metal hip resurfacing  

PubMed Central

Bone resorption of the proximal femur is a frequent complication of total hip replacement. As hip resurfacing (HR) may load the bone more physiologically, we measured proximal femur bone mineral density (BMD) in 21 patients with HR. DEXA analysis was performed in the 7 Gruen zones and in the femoral neck pre-operatively and at 3, 9, and 24-months post-operatively. In Gruen zone-2 the BMD ratio decreased to 90±18.8% (p=0.0009) at 3-months and completely restored at 24-months to 100±17.7% (p=0.01). In Gruen zone-7 the BMD ratio decreased to 93±15.3% (p=0.05) by 3 months and surpassed the baseline to 105±14.8% (p=0.01) at 24-months. A positive correlation was observed between valgus positioning of the femoral component and BMD in Gruen zone-2 and 7 respectively. HR preserves the bone-stock of the proximal femur. When the femoral component is implanted in a valgus position BMD is further enhanced, thus potentially reducing the risk of femoral neck fractures.

Cadossi, Matteo; Moroni, Antonio; Romagnoli, Matteo; Chiarello, Eugenio; Faldini, Cesare; Giannini, Sandro

2010-01-01

264

Auditory and visual health after ten years of exposure to metal-on-metal hip prostheses: a cross-sectional study follow up.  

PubMed

Case reports of patients with mal-functioning metal-on-metal hip replacement (MoMHR) prostheses suggest an association of elevated circulating metal levels with visual and auditory dysfunction. However, it is unknown if this is a cumulative exposure effect and the impact of prolonged low level exposure, relevant to the majority of patients with a well-functioning prosthesis, has not been studied. Twenty four male patients with a well-functioning MoMHR and an age and time since surgery matched group of 24 male patients with conventional total hip arthroplasty (THA) underwent clinical and electrophysiological assessment of their visual and auditory health at a mean of ten years after surgery. Median circulating cobalt and chromium concentrations were higher in patients after MoMHR versus those with THA (P<0.0001), but were within the Medicines and Healthcare Products Regulatory Agency (UK) investigation threshold. Subjective auditory tests including pure tone audiometric and speech discrimination findings were similar between groups (P>0.05). Objective assessments, including amplitude and signal-to-noise ratio of transient evoked and distortion product oto-acoustic emissions (TEOAE and DPOAE, respectively), were similar for all the frequencies tested (P>0.05). Auditory brainstem responses (ABR) and cortical evoked response audiometry (ACR) were also similar between groups (P>0.05). Ophthalmological evaluations, including self-reported visual function by visual functioning questionnaire, as well as binocular low contrast visual acuity and colour vision were similar between groups (P>0.05). Retinal nerve fibre layer thickness and macular volume measured by optical coherence tomography were also similar between groups (P>0.05). In the presence of moderately elevated metal levels associated with well-functioning implants, MoMHR exposure does not associate with clinically demonstrable visual or auditory dysfunction. PMID:24621561

Prentice, Jennifer R; Blackwell, Christopher S; Raoof, Naz; Bacon, Paul; Ray, Jaydip; Hickman, Simon J; Wilkinson, J Mark

2014-01-01

265

Admetal-induced substrate surface restructuring during metal-on-metal electrochemical deposition studied by in situ scanning tunneling microscopy  

NASA Astrophysics Data System (ADS)

Based on time-dependent in situ scanning tunneling microscopy (STM) studies, we demonstrate that for Ni on Ag(111) and Ru on Au(111), electrochemical metal-on-metal deposition can result in pronounced substrate surface restructuring. For Ni/Ag(111), we observe that at low deposition flux and low coverage, Ni submonolayer islands at steps are partly embedded in the Ag terraces, whereas at higher deposition flux and higher coverage, substrate restructuring results in the formation of monolayer bays in the Ag terraces. We suggest that this restructuring process proceeds predominantly via step edge diffusion of Ag atoms. For Ru/Au(111), the formation of fjords and monolayer holes in the Au terraces is observed at low and high Ru coverage, respectively. The importance of the Au surface mobility for the restructuring process is demonstrated by comparing experiments in H 2SO 4 and HCl solutions, in which Au exhibits strongly different surface mobilities. For this system, restructuring involves Au diffusion along Au steps, Au atom detachment from the Au steps, and upward exchange diffusion. According to these observations and their comparison with similar findings for vacuum deposition, we conclude that this restructuring requires (i) a high substrate surface mobility and (ii) a stronger bonding of substrate atoms to deposit islands than to the substrate.

Maroun, F.; Morin, S.; Lachenwitzer, A.; Magnussen, O. M.; Behm, R. J.

2000-07-01

266

The relationship between head-neck ratio and pseudotumour formation in metal-on-metal resurfacing arthroplasty of the hip.  

PubMed

Pseudotumour is a rare but important complication of metal-on-metal hip resurfacing that occurs much more commonly in women than in men. We examined the relationship between head-neck ratio (HNR) and pseudotumour formation in 18 resurfaced hips (18 patients) revised for pseudotumour and 42 asymptomatic control resurfaced hips (42 patients). Patients in whom pseudotumour formation had occurred had higher pre-operative HNR than the control patients (mean 1.37 (sd 0.10) vs mean 1.30 (sd 0.08) p = 0.001). At operation the patients with pseudotumours had a greater reduction in the size of their femoral heads (p = 0.035) and subsequently had greater neck narrowing (mean 10.1% (sd 7.2) vs mean 3.8% (sd 3.2) p < 0.001). No female patient with a pre-operative HNR ? 1.3 developed a pseudotumour. We suggest that reducing the size of the femoral head, made possible by a high pre-operative HNR, increases the risk of impingement and edge loading, and may contribute to high wear and pseudotumour formation. As the incidence of pseudotumour is low in men, it appears safe to perform resurfacing in men. However, this study suggests that it is also reasonable to resurface in women with a pre-operative HNR ? 1.3. PMID:21037347

Grammatopoulos, G; Pandit, H; Murray, D W; Gill, H S

2010-11-01

267

Metal ion levels and revision rates in metal-on-metal hip resurfacing arthroplasty: a comparative study.  

PubMed

Metal-on-metal (MoM) bearings in hip surgery are related to increased blood levels of metal ions. The nature of the relationship between ion levels and failure is still not fully understood. This study compares three cohorts of patients, 120 patients in each cohort, treated with a hip resurfacing arthroplasty, grouped by brand and diameter of femoral component on average four years postoperatively: Birmingham Hip Resurfacing ?50 mm, Durom resurfacing ?50 mm and Durom resurfacing <50 mm. The median blood ion levels of cobalt and chromium were significantly lower in the cohort with the large Durom resurfacing than the other two cohorts (P<0.05). The large BHR and large Durom HRA had revision rates of 3.3%. The small Durom HRA had a revision rate of 8.3%. Elevated blood ion levels can indicate a failing MoM bearing. The large BHR and large Durom HRA have similar revision rates yet the large Durom HRA had significantly lower metal ion levels. When similar ion levels were reported for BHR and small Durom the latter had significantly higher revision rates. This suggests ion levels do not absolutely predict the rate of HRA failure. Since MoM generation of metal ions is not the sole reason of failure, regular clinical and radiographic follow-up should also be in place for patients with these joints. PMID:24500833

Robinson, Patrick G; Wilkinson, Andrew J; Meek, Robert M D

2014-01-01

268

A comparison of the diagnostic accuracy of MARS MRI and ultrasound of the painful metal-on-metal hip arthroplasty.  

PubMed

Background and purpose - Metal artifact reduction sequence (MARS) MRI and ultrasound scanning (USS) can both be used to detect pseudotumors, abductor muscle atrophy, and tendinous pathology in patients with painful metal-on-metal (MOM) hip arthroplasty. We wanted to determine the diagnostic test characteristics of USS using MARS MRI as a reference for detection of pseudotumors and muscle atrophy. Patients and methods - We performed a prospective cohort study to compare MARS MRI and USS findings in 19 consecutive patients with unilateral MOM hips. Protocolized USS was performed by consultant musculoskeletal radiologists who were blinded regarding clinical details. Reports were independently compared with MARS MRI, the imaging gold standard, to calculate predictive values. Results - The prevalence of pseudotumors on MARS MRI was 68% (95% CI: 43-87) and on USS it was 53% (CI: 29-76). The sensitivity of USS in detecting pseudotumors was 69% (CI 39-91) and the specificity was 83% (CI: 36-97). The sensitivity of detection of abductor muscle atrophy was 47% (CI: 24-71). In addition, joint effusion was detected in 10 cases by USS and none were seen by MARS MRI. Interpretation - We found a poor agreement between USS and MARS MRI. USS was inferior to MARS MRI for detection of pseudotumors and muscle atrophy, but it was superior for detection of joint effusion and tendinous pathologies. MARS MRI is more advantageous than USS for practical reasons, including preoperative planning and longitudinal comparison. PMID:24694273

Siddiqui, Imran A; Sabah, Shiraz A; Satchithananda, Keshthra; Lim, Adrian K; Cro, Suzie; Henckel, Johann; Skinner, John A; Hart, Alister J

2014-08-01

269

Lymphoid aggregates that resemble tertiary lymphoid organs define a specific pathological subset in metal-on-metal hip replacements.  

PubMed

Aseptic lymphocyte-dominated vasculitis-associated lesion (ALVAL) has been used to describe the histological lesion associated with metal-on-metal (M-M) bearings. We tested the hypothesis that the lymphoid aggregates, associated with ALVAL lesions resemble tertiary lymphoid organs (TLOs). Histopathological changes were examined in the periprosthetic tissue of 62 M-M hip replacements requiring revision surgery, with particular emphasis on the characteristics and pattern of the lymphocytic infiltrate. Immunofluorescence and immunohistochemistry were used to study the classical features of TLOs in cases where large organized lymphoid follicles were present. Synchrotron X-ray fluorescence (XRF) measurements were undertaken to detect localisation of implant derived ions/particles within the samples. Based on type of lymphocytic infiltrates, three different categories were recognised; diffuse aggregates (51%), T cell aggregates (20%), and organised lymphoid aggregates (29%). Further investigation of tissues with organised lymphoid aggregates showed that these tissues recapitulate many of the features of TLOs with T cells and B cells organised into discrete areas, the presence of follicular dendritic cells, acquisition of high endothelial venule like phenotype by blood vessels, expression of lymphoid chemokines and the presence of plasma cells. Co-localisation of implant-derived metals with lymphoid aggregates was observed. These findings suggest that in addition to the well described general foreign body reaction mediated by macrophages and a T cell mediated type IV hypersensitivity response, an under-recognized immunological reaction to metal wear debris involving B cells and the formation of tertiary lymphoid organs occurs in a distinct subset of patients with M-M implants. PMID:23723985

Mittal, Saloni; Revell, Matthew; Barone, Francesca; Hardie, Debbie L; Matharu, Gulraj S; Davenport, Alison J; Martin, Richard A; Grant, Melissa; Mosselmans, Frederick; Pynsent, Paul; Sumathi, Vaiyapuri P; Addison, Owen; Revell, Peter A; Buckley, Christopher D

2013-01-01

270

Transient elastohydrodynamic lubrication analysis of a novel metal-on-metal hip prosthesis with a non-spherical femoral bearing surface.  

PubMed

Effective lubrication performance of metal-on-metal hip implants only requires optimum conformity within the main loaded area, while it is advantageous to increase the clearance in the equatorial region. Such a varying clearance can be achieved by using non-spherical bearing surfaces for either acetabular or femoral components. An elastohydrodynamic lubrication model of a novel metal-on-metal hip prosthesis using a non-spherical femoral bearing surface against a spherical cup was solved under loading and motion conditions specified by ISO standard. A full numerical methodology of considering the geometric variation in the rotating non-spherical head in elastohydrodynamic lubrication solution was presented, which is applicable to all non-spherical head designs. The lubrication performance of a hip prosthesis using a specific non-spherical femoral head, Alpharabola, was analysed and compared with those of spherical bearing surfaces and a non-spherical Alpharabola cup investigated in previous studies. The sensitivity of the lubrication performance to the anteversion angle of the Alpharabola head was also investigated. Results showed that the non-spherical head introduced a large squeeze-film action and also led to a large variation in clearance within the loaded area. With the same equatorial clearance, the lubrication performance of the metal-on-metal hip prosthesis using an Alpharabola head was better than that of the conventional spherical bearings but worse than that of the metal-on-metal hip prosthesis using an Alpharabola cup. The reduction in the lubrication performance caused by the initial anteversion angle of the non-spherical head was small, compared with the improvement resulted from the non-spherical geometry. PMID:21381485

Meng, Q E; Liu, F; Fisher, J; Jin, Z M

2011-01-01

271

(v) Simulation and measurement of wear in metal-on-metal bearings in vitro- understanding the reasons for increased wear  

PubMed Central

A new Stratified Approach For Enhanced Reliability (SAFER) pre-clinical simulation testing of joint prostheses has been described in a preceding paper in this volume. The application of SAFER in vitro simulation and testing to metal-on-metal bearings is described in this review paper. The review aims to provide further understanding of the reasons for, and causes of, increased wear in metal-on-metal hips in a proportion of patients. Variation in positioning (mal-positioning) of the head and cup in hip prostheses results in the head contacting the rim of the cup and producing increased wear. Variation in both translational and rotational positioning has been investigated. Variation in translational positioning of the centres of the head and cup, which is not detected on radiographs, is a frequent occurrence clinically and can result in a substantial increase in wear rate. The variation in translational positioning acts synergistically with variation in rotational positioning to produce substantial increases in wear. These recent findings are consistent with the wear mechanisms and formation of stripe wear reported for ceramic-on-ceramic bearings over a decade ago, and provide insight into the reasons for the variation and increases in the wear rate found clinically in metal-on-metal hips in specific patients, which may cause premature failure.

Fisher, John; Al Hajjar, Mazen; Williams, Sophie; Tipper, Joanne; Ingham, Eileen; Jennings, Louise

2012-01-01

272

Activation of Noble Metals on Metal-Carbide Surfaces: Novel Catalysts for CO Oxidation, Desulfurization and Hydrogenation Reactions  

SciTech Connect

This perspective article focuses on the physical and chemical properties of highly active catalysts for CO oxidation, desulfurization and hydrogenation reactions generated by depositing noble metals on metal-carbide surfaces. To rationalize structure-reactivity relationships for these novel catalysts, well-defined systems are required. High-resolution photoemission, scanning tunneling microscopy (STM) and first-principles periodic density-functional (DF) calculations have been used to study the interaction of metals of Groups 9, 10 and 11 with MC(001) (M = Ti, Zr, V, Mo) surfaces. DF calculations give adsorption energies that range from 2 eV (Cu, Ag, Au) to 6 eV (Co, Rh, Ir). STM images show that Au, Cu, Ni and Pt grow on the carbide substrates forming two-dimensional islands at very low coverage, and three-dimensional islands at medium and large coverages. In many systems, the results of DF calculations point to the preferential formation of admetal-C bonds with significant electronic perturbations in the admetal. TiC(001) and ZrC(001) transfer some electron density to the admetals facilitating bonding of the adatom with electron-acceptor molecules (CO, O{sub 2}, C{sub 2}H{sub 4}, SO{sub 2}, thiophene, etc.). For example, the Cu/TiC(001) and Au/TiC(001) systems are able to cleave both S-O bonds of SO{sub 2} at a temperature as low as 150 K, displaying a reactivity much larger than that of TiC(001) or extended surfaces of bulk copper and gold. At temperatures below 200 K, Au/TiC is able to dissociate O{sub 2} and perform the 2CO + O{sub 2} {yields} 2CO{sub 2} reaction. Furthermore, in spite of the very poor hydrodesulfurization performance of TiC(001) or Au(111), a Au/TiC(001) surface displays an activity for the hydrodesulfurization of thiophene higher than that of conventional Ni/MoS{sub x} catalysts. In general, the Au/TiC system is more chemically active than systems generated by depositing Au nanoparticles on oxide surfaces. Thus, metal carbides are excellent supports for enhancing the chemical reactivity of noble metals.

Rodriguez J. A.; Illas, F.

2012-01-01

273

High incidence of loosening at 5-year follow-up of a cemented metal-on-metal acetabular component in THR  

Microsoft Academic Search

Introduction  High rates of polyethylene wear in metal-on-polyethylene-bearing surfaces correlate with peri-prosthetic osteolysis and early\\u000a loosening. Hard-bearing surfaces have been used as they may decrease the production of debris and improve survival of the\\u000a prosthesis. The aim of this study is to ascertain the rate of early loosening of a polyethylene cemented acetabular component\\u000a with a metal-on-metal (MOM) insert.\\u000a \\u000a \\u000a \\u000a Methods  Between 1997

S. Descamps; B. Bouillet; S. Boisgard; J. P. Levai

2009-01-01

274

Is second generation metal-on-metal primary total hip arthroplasty with a 28 mm head a worthy option?: a 12- to 18-year follow-up study.  

PubMed

To determine whether MoM THA with a small head is still worthy of use, we investigated survivorship, complications, and factors influencing failure. Of 149 consecutive patients (195 hips), 141 (180 hips) of mean age 43 (19-55) years were available for review at a mean of 14.4 years postoperatively. Survivorship for cup revision for any cause was 97.8% at 18.4 years postoperatively. Nine hips generated complaints of groin pain; six showed periacetabular osteolysis, one had pain without radiological change, and two were diagnosed as symptomatic pseudotumors. Four of six hips with periacetabular osteolysis or aseptic loosening were revised. Surgery- and patient-related factors had no effect in results. Our results are encouraging, however, further study will be necessary to determine the incidence and fates of pseudotumors after MoM THA with a small head. PMID:23890829

Hwang, Kyu-Tae; Kim, Young-Ho; Kim, Yee-Suk; Choi, Il-Yong

2013-12-01

275

Metal-on-Metal Cups Cemented Into Reinforcement Rings: A Possible New Acetabular Reconstruction Procedure for Young and Active Patients  

Microsoft Academic Search

The purpose of this study was to evaluate the clinical and radiological results of Metasul cups cemented into reinforcement rings for young and active patients. Twenty-three total hip arthroplasties with Metasul cups were cemented into Muller reinforcement rings. Mean follow-up was 6.1 years (5-10). At final follow-up, the Harris hip score increased from 62.2 (39-85) to 95.2 (84-100, P =

Julien Girard; Antoine Combes; Stephane Herent; Henri Migaud

2011-01-01

276

Survivorship of Conserve® Plus monoblock metal-on-metal hip resurfacing sockets: radiographic midterm results of 580 patients.  

PubMed

Resurfacing systems use press-fit, monoblock, cobalt chrome alloy acetabular sockets because of the material's ability to withstand stresses while accommodating a large femoral head. Despite the widespread use of these types of sockets for both hip resurfacing and total hip replacement, there is a paucity of literature assessing the outcomes of these cups in particular. The 10 year survivorship of the Conserve® Plus monoblock acetabular component used in this study was 98.3% with small pelvic osteolytic lesions suspected in only 2.3%. This study highlights the excellent radiographic survivorship profile of the Conserve® Plus socket. PMID:21435491

Hulst, J B; Ball, S T; Wu, G; Le Duff, Michel J; Woon, R P; Amstutz, Harlan C

2011-04-01

277

'Severe' wear challenge to 'as-cast' and 'double heat-treated' large-diameter metal-on-metal hip bearings.  

PubMed

The wear generation of double-heat-treated and as-cast large-diameter metal-on-metal (MOM) hip bearings was investigated using standard- and 'severe'-gait simulations. The test hypothesis was that double heat treatment would change MOM hip wear compared with the as-cast condition. Two groups of high-carbon MOM bearings of 40 mm diameter were manufactured and subjected to either hot isostatic pressing (HIP) and solution annealing (SA) or no heat treatment (as cast). The results showed no statistical difference between the two groups under both running-in and steady state conditions. Even under the most 'severe'-gait simulation published to date, the mean volumetric wear rates were 2.9 and 3.9 mm3 per 10(6) cycles for the HIP-SA and as-cast bearings respectively, showing a ten-fold increase in wear compared with walking. These differences were not statistically different; therefore our hypothesis was negated. Changes in alloy microstructure do not appear to influence the wear behaviour of high-carbon cast MOM articulations with similar chemical compositions. This is in sharp contrast with the published significance of bearing diameter and radial clearance on the wear of MOM hip bearings. PMID:16669382

Bowsher, J G; Nevelos, J; Williams, P A; Shelton, J C

2006-02-01

278

Accuracy of methods for calculating volumetric wear from coordinate measuring machine data of retrieved metal-on-metal hip joint implants.  

PubMed

This study compared the accuracy and sensitivity of several numerical methods employing spherical or plane triangles for calculating the volumetric wear of retrieved metal-on-metal hip joint implants from coordinate measuring machine measurements. Five methods, one using spherical triangles and four using plane triangles to represent the bearing and the best-fit surfaces, were assessed and compared on a perfect hemisphere model and a hemi-ellipsoid model (i.e. unworn models), computer-generated wear models and wear-tested femoral balls, with point spacings of 0.5, 1, 2 and 3?mm. The results showed that the algorithm (Method 1) employing spherical triangles to represent the bearing surface and to scale the mesh to the best-fit surfaces produced adequate accuracy for the wear volume with point spacings of 0.5, 1, 2 and 3?mm. The algorithms (Methods 2-4) using plane triangles to represent the bearing surface and to scale the mesh to the best-fit surface also produced accuracies that were comparable to that with spherical triangles. In contrast, if the bearing surface was represented with a mesh of plane triangles and the best-fit surface was taken as a smooth surface without discretization (Method 5), the algorithm produced much lower accuracy with a point spacing of 0.5?mm than Methods 1-4 with a point spacing of 3?mm. PMID:24531891

Lu, Zhen; McKellop, Harry A

2014-03-01

279

The relationship between the angle of version and rate of wear of retrieved metal-on-metal resurfacings: a prospective, CT-based study.  

PubMed

We measured the orientation of the acetabular and femoral components in 45 patients (33 men, 12 women) with a mean age of 53.4 years (30 to 74) who had undergone revision of metal-on-metal hip resurfacings. Three-dimensional CT was used to measure the inclination and version of the acetabular component, femoral version and the horizontal femoral offset, and the linear wear of the removed acetabular components was measured using a roundness machine. We found that acetabular version and combined version of the acetabular and femoral components were weakly positively correlated with the rate of wear. The acetabular inclination angle was strongly positively correlated with the rate of wear. Femoral version was weakly negatively correlated with the rate of wear. Application of a threshold of > 5 ?m/year for the rate of wear in order to separate the revisions into low or high wearing groups showed that more high wearing components were implanted outside Lewinnek's safe zone, but that this was mainly due to the inclination of the acetabular component, which was the only parameter that significantly differed between the groups. We were unable to show that excess version of the acetabular component alone or combined with femoral version was associated with an increase in the rate of wear based on our assessment of version using CT. PMID:21357951

Hart, A J; Ilo, K; Underwood, R; Cann, P; Henckel, J; Lewis, A; Cobb, J; Skinner, J

2011-03-01

280

Evaluation of the accuracy of three popular regression equations for hip joint centre estimation using computerised tomography measurements for metal-on-metal hip resurfacing arthroplasty patients.  

PubMed

We investigated the accuracy of the regression equations by Bell et al., Davis III et al. and Harrington et al. for hip joint centre (HJC) estimation against the gold standard of computerised tomography (CT) measurements of HJC for 18 patients with metal-on-metal hip resurfacing arthroplasty (MoMHRA). The HJCs were estimated based on the position of the left and right Anterior Superior Iliac Spine (ASIS) and the left and right Posterior Superior Iliac Spine (PSIS) identified from a CT scan. Of the three tested regression equations, only those of Harrington et al. produced results that were not significantly different from the patient's 'true' HJCs as measured from the CT scan in all three directions when analysing left and right hips together for both resurfaced and native hips. When native and resurfaced hips were pooled and analysed for left and right, separately, the Harrington et al. regression equations showed significantly different results in the ML direction. Similar estimation errors were observed for native and resurfaced hips. Since none of the methods tested performed particularly well, we suggest using medical imaging if accurate estimates of HJCs are required. PMID:23454045

Andersen, Michael S; Mellon, Stephen; Grammatopoulos, George; Gill, Harinderjit S

2013-09-01

281

Prediction of Impact Shock Vibrations at Tennis Player's Wrist Joint: Comparison between Conventional Weight Racket and Light Weight Racket with Super Large Head Size  

Microsoft Academic Search

The lightweight racket with handle-light configuration and large head size is recent tendency of high-tech tennis rackets, increasing power or post-impact ball velocity with an increasing racket swing speed. This paper investigated the performance of lightweight tennis racket with super-large head size in terms of feel or comfort. It predicted the effect of the mass and mass distribution of super-large

Yoshihiko Kawazoe; Yukihiro Takeda; Masamichi Nakagawa; Federico Casolo; Ryoso Tomosue; Keiko Yoshinari

2010-01-01

282

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

PubMed

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 three 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 (p < 0.01) amounts of serum Co and Cr compared to controls as early as 3 months post-op (Group 1:1.2 ppb Co, 1.5 ppb Cr; Group 2: 3.4 ppb Co, 5.4 ppb Cr; Group 3: 0.01 ppb Co, 0.1 ppb Cr). However, only after 1-4 years post-op did 56% of Group 1 develop metal-reactivity (vs. 5% pre-op, metal-LTT, SI > 2), 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 versus non-reactive Group-1 participants (p < 0.04). CD4+CD69+ T-helper lymphocytes (but not CD8+) and IL-1?, IL-12, and IL-6 cytokines were all significantly elevated in metal-reactive versus non-reactive Group 1 participants. Our results showed that lymphocyte reactivity to metals can develop within the first 1-4 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

Hallab, Nadim J; Caicedo, Marco; McAllister, Kyron; Skipor, Anastasia; Amstutz, Harlan; Jacobs, Joshua J

2013-02-01

283

Serum Metal Levels and Bearing Surfaces in Total Hip Arthroplasty  

Microsoft Academic Search

This study evaluates steady-state serum metal levels in patients with 4 different combinations of fixation modalities, materials, and bearing couples. Forty patients with a minimum of 5 years of follow-up and with well-functioning primary total hip arthroplasty were recruited to have serum metal levels measured. Serum chromium and cobalt levels in the metal-on-metal cohort were significantly higher (P < .05)

Vijay J. Rasquinha; Chitranjan S. Ranawat; Joanne Weiskopf; Jose A. Rodriguez; Anastasia K. Skipor; Joshua J. Jacobs

2006-01-01

284

Survivorship of total hip replacements.  

PubMed

The survivorship of total hip replacements in patients operated on at the Royal National Orthopaedic Hospital has been analysed using standard actuarial methods. Between 1963 and 1972 173 metal-on-metal prostheses of various developmental designs were inserted. Between 1969 and 1972 248 prostheses of one design using a metal femoral component and plastic cup were used. The patients were surveyed retrospectively and for each the actual follow-up period was determined as well as the eventual outcome. The criterion of "survival" was that the prosthesis was still in situ and all such prostheses were regarded as "survivors", regardless of whether the patients experienced pain or loss of function. The survivorship was then determined by constructing life tables. The results indicate that for metal-on-metal prostheses the overall probability of survival was only 53 per cent after 11 years and the average annual probability of removal, irrespective of cause, was 5.5 per cent. The results were better for metal-on-plastic prostheses with figures of 88 per cent after eight years and 1.5 per cent respectively. For both prostheses the predominant reason for failure was loosening and the annual rate of removal for loosening increased as the follow-up time increased, suggesting that loosening was a wearing out process. The advantages of the survivorship method of analysis as compared with conventional methods are discussed. PMID:7364829

Dobbs, H S

1980-05-01

285

The changing paradigm of revision of total hip replacement in the presence of osteolysis.  

PubMed

Osteolysis tends to remain clinically silent and presents a treatment challenge. In the past, the progression of implant wear was used to determine the timing of interventions. Recent reports of lesions associated with metal-on-metal implants and trunnion corrosion with femoral head sizes larger than 32 mm suggest that other mechanisms of wear debris production may be present; observation alone may not provide adequate monitoring. Advanced imaging modalities, such as MRI, should be used along with routine radiography to assess soft-tissue involvement and the size of osteolytic lesions. Intraoperative mechanical stress applied to the acetabular cup helps determine if revision or retention is selected when osteolysis is present. Options for the management of acetabular osteolysis include porous metal cups, oblong cups, antiprotrusio cages, impaction grafting, structural grafts, and, more recently, versatile porous metal cups. Porous metal cups can be used with or without augments or as cup-cage constructs. Porous metal cups have shown excellent results at short-term follow-ups. Modular, uncemented, titanium stems are now more commonly used for femoral revisions. Impaction grafting and allograft-prosthesis composites are occasionally useful in femoral revision surgery. A high incidence of adverse tissue reactions has been reported with metal-on-metal bearings with large heads. Recent focus also has been directed to debris generation by the modular junctions in these bearings. Removal of all sources of debris generation should be attempted during revision of metal-on-metal hip replacements. A thorough débridement of soft-tissue masses and the use of ceramic heads should be considered. PMID:23395027

Chatrath, Vikram; Beaulé, Paul E

2013-01-01

286

Diamond coated total hip replacements.  

PubMed

Diamond has many superior, desired characteristics of implant materials such as low friction, high wear and corrosion resistance, and well bonding surface to bone. The potential of diamond for total hip replacement implants was studied in the form of amorphous diamond coatings on conventional metal implant materials. Amorphous diamond coatings (sp3 bonding fraction 80%, thickness 0.2 to 10 microns) were deposited on stainless steel AISI316L, Ti6A14V, and CoCrMo alloys using filtered pulsed plasma are discharge method. Superior attachment of coatings to the implant materials was achieved by using high energy plasma beams to deposit amorphous diamond and proper intermediate layers. Previously it was shown that these coatings are biocompatible causing no local tissue reactions. Tribologic studies using a pin on disk apparatus with coated or uncoated implant materials in 1 wt.% NaCl distilled water were performed. A simplified hip joint simulator was used for preliminary testing of metal on polyethylene and metal on metal artificial hip joints modified with amorphous diamond coating. The average coefficients of friction were typically in the range of 0.03 to 0.11 for amorphous diamond coated materials. In the case of metal on metal hip implants, the average friction during initial running in period was improved (coefficient of friction = 0.07) compared with the same metal on metal pair (coefficient of friction = 0.22) and sliding was significantly smoother. In pin on disk wear tests, the average wear factors obtained were 140.10(-6), 5.0.10(-6), and < 0.1.10(-6) mm3/Nm for the pairs of AISI316L, CoCrMo, and the same materials with amorphous diamond coating. The corrosion rates of these implant materials in 10 wt.% HCl solution were decreased by a factor of 10,000 to 15,000 and any damage of the coatings was not observed in 6 months. The results of the tests show that in all the combinations studied, amorphous diamond coating improved definitely the wear and corrosion resistance compared with the uncoated materials. PMID:9678039

Lappalainen, R; Anttila, A; Heinonen, H

1998-07-01

287

The sensitivity, specificity and predictive values of raised plasma metal ion levels in the diagnosis of adverse reaction to metal debris in symptomatic patients with a metal-on-metal arthroplasty of the hip.  

PubMed

Plasma levels of cobalt and chromium ions and Metal Artefact Reduction Sequence (MARS)-MRI scans were performed on patients with 209 consecutive, unilateral, symptomatic metal-on-metal (MoM) hip arthroplasties. There was wide variation in plasma cobalt and chromium levels, and MARS-MRI scans were positive for adverse reaction to metal debris (ARMD) in 84 hips (40%). There was a significant difference in the median plasma cobalt and chromium levels between those with positive and negative MARS-MRI scans (p < 0.001). Compared with MARS-MRI as the potential reference standard for the diagnosis of ARMD, the sensitivity of metal ion analysis for cobalt or chromium with a cut-off of > 7 µg/l was 57%. The specificity was 65%, positive predictive value was 52% and the negative predictive value was 69% in symptomatic patients. A lowered threshold of > 3.5 µg/l for cobalt and chromium ion levels improved the sensitivity and negative predictive value to 86% and 74% but at the expense of specificity (27%) and positive predictive value (44%). Metal ion analysis is not recommended as a sole indirect screening test in the surveillance of symptomatic patients with a MoM arthroplasty. The investigating clinicians should have a low threshold for obtaining cross-sectional imaging in these patients, even in the presence of low plasma metal ion levels. PMID:22844044

Malek, I A; King, A; Sharma, H; Malek, S; Lyons, K; Jones, S; John, A

2012-08-01

288

Raised levels of metal ions in the blood in patients who have undergone uncemented metal-on-polyethylene Trident-Accolade total hip replacement.  

PubMed

The issues surrounding raised levels of metal ions in the blood following large head metal-on-metal total hip replacement (THR), such as cobalt and chromium, have been well documented. Despite the national popularity of uncemented metal-on-polyethylene (MoP) THR using a large-diameter femoral head, few papers have reported the levels of metal ions in the blood following this combination. Following an isolated failure of a 44 mm Trident-Accolade uncemented THR associated with severe wear between the femoral head and the trunnion in the presence of markedly elevated levels of cobalt ions in the blood, we investigated the relationship between modular femoral head diameter and the levels of cobalt and chromium ions in the blood following this THR. A total of 69 patients received an uncemented Trident-Accolade MoP THR in 2009. Of these, 43 patients (23 men and 20 women, mean age 67.0 years) were recruited and had levels of cobalt and chromium ions in the blood measured between May and June 2012. The patients were then divided into three groups according to the diameter of the femoral head used: 12 patients in the 28 mm group (controls), 18 patients in the 36 mm group and 13 patients in the 40 mm group. A total of four patients had identical bilateral prostheses in situ at phlebotomy: one each in the 28 mm and 36 mm groups and two in the 40 mm group. There was a significant increase in the mean levels of cobalt ions in the blood in those with a 36 mm diameter femoral head compared with those with a 28 mm diameter head (p = 0.013). The levels of cobalt ions in the blood were raised in those with a 40 mm diameter head but there was no statistically significant difference between this group and the control group (p = 0.152). The levels of chromium ions in the blood were normal in all patients. The clinical significance of this finding is unclear, but we have stopped using femoral heads with a diameter of ? 36 mm, and await further larger studies to clarify whether, for instance, this issue particularly affects this combination of components. PMID:24395309

Craig, P; Bancroft, G; Burton, A; Collier, S; Shaylor, P; Sinha, A

2014-01-01

289

Prediction of Impact Shock Vibrations at Tennis Player's Wrist Joint: Comparison between Conventional Weight Racket and Light Weight Racket with Super Large Head Size  

NASA Astrophysics Data System (ADS)

The lightweight racket with handle-light configuration and large head size is recent tendency of high-tech tennis rackets, increasing power or post-impact ball velocity with an increasing racket swing speed. This paper investigated the performance of lightweight tennis racket with super-large head size in terms of feel or comfort. It predicted the effect of the mass and mass distribution of super-large sized rackets on the impact shock vibrations of the racket handle and the player's wrist joint when a player hits a flat forehand drive. The prediction is based on the identification of the racket characteristics, the damping of the racket-arm system, equivalent mass of the player's arm system and the approximate nonlinear impact analysis in tennis. A super-light weight balanced racket (mass: 292 g, the center of gravity LG: 363 mm from the butt end) and a conventional weight and weight balanced racket (349 g, LG: 323 mm) are selected as representatives. They are the super-large sized rackets made of carbon graphite with a head size of 120 square inches and the same geometry. The result showed that the shock vibration of the super-light weight balanced racket with super-large sized head is much larger than that of the conventional weight balanced type racket. It also showed that the sweet area of the former in terms of the shock vibration shifts from the center to the topside on the racket face compared to the latter. This is because the location of the grip on the racket handle is further from the location of the node on the handle of the first mode of super-light racket than that of the conventional weight racket.

Kawazoe, Yoshihiko; Takeda, Yukihiro; Nakagawa, Masamichi; Casolo, Federico; Tomosue, Ryoso; Yoshinari, Keiko

290

Effect of femoral head size on risk of revision for dislocation after total hip arthroplasty  

PubMed Central

Background and purpose Previous population-based registry studies have shown that larger femoral head size is associated with reduced risk of revision for dislocation. However, the previous data have not included large numbers of hip resurfacing arthroplasties or large metal-on-metal (> 36-mm) femoral head arthroplasties. We evaluated the association between femoral component head size and the risk of revision for dislocation after THA by using Finnish Arthroplasty Register data. Patients and methods 42,379 patients who were operated during 1996–2010 fulfilled our criteria. 18 different cup/stem combinations were included. The head-size groups studied (numbers of cases) were 28 mm (23,800), 32 mm (4,815), 36 mm (3,320), and > 36 mm (10,444). Other risk factors studied were sex, age group (18–49 years, 50–59 years, 60–69 years, 70–79 years, and > 80 years), and time period of operation (1996–2000, 2001–2005, 2006–2010). Results The adjusted risk ratio in the Cox model for a revision operation due to dislocation was 0.40 (95% CI: 0.26–0.62) for 32-mm head size, 0.41 (0.24–0.70) for 36-mm head size, and 0.09 (0.05–0.17) for > 36-mm head size compared to implants with a head size of 28 mm. Interpretation Larger femoral heads clearly reduce the risk of dislocation. The difference in using heads of > 36 mm as opposed to 28-mm heads for the overall revision rate at 10 years follow-up is about 2%. Thus, although attractive from a mechanical point of view, based on recent less favorable clinical outcome data on these large heads, consisting mainly of metal-on-metal prostheses, one should be cautious using these implants.

Kostensalo, Inari; Junnila, Mika; Virolainen, Petri; Remes, Ville; Matilainen, Markus; Vahlberg, Tero; Pulkkinen, Pekka; Eskelinen, Antti; Makela, Keijo T

2013-01-01

291

A frictional study of total hip joint replacements  

NASA Astrophysics Data System (ADS)

Polymeric wear debris produced by articulation of the femoral head against the ultra-high-molecular-weight polyethylene socket of a total hip replacement has been implicated as the main cause of osteolysis and subsequent failure of these implants. Potential solutions to this problem are to employ hard bearing surface combinations such as metal-on-metal or ceramic-on-ceramic prostheses. The aim of this study was to investigate the difference in lubrication modes and friction of a range of material combinations using synthetic and biological fluids as the lubricants. The experimental results were compared with theoretical predictions of film thicknesses and lubrication modes. A strong correlation was observed between experiment and theory when employing carboxy methyl cellulose (CMC) fluids as the lubricant. Under these conditions the ceramic-on-ceramic joints showed full fluid film lubrication while the metal-on-metal, metal-on-plastic, diamond-like carbon-coated stainless steel (DLC)-on-plastic and ceramic-on-plastic prostheses operated under a mixed lubrication regime. With bovine serum as the lubricant in the all ceramic joints, however, the full fluid film lubrication was inhibited due to adsorbed proteins. In the metal-on-metal joints this adsorbed protein layer acted to reduce the friction while in the ceramic coupling the friction was increased. The use of bovine serum as the lubricant also significantly increased the friction in both the metal-on-plastic and ceramic-on-plastic joints. The friction produced by the DLC-on-plastic joints depended on the quality of the coating. Those joints with a less consistent coating and therefore a higher surface roughness gave significantly higher friction than the smoother, more consistently coated heads.

Scholes, S. C.; Unsworth, A.; Goldsmith, A. A. J.

2000-12-01

292

A frictional study of total hip joint replacements.  

PubMed

Polymeric wear debris produced by articulation of the femoral head against the ultra-high-molecular-weight polyethylene socket of a total hip replacement has been implicated as the main cause of osteolysis and subsequent failure of these implants. Potential solutions to this problem are to employ hard bearing surface combinations such as metal-on-metal or ceramic-on-ceramic prostheses. The aim of this study was to investigate the difference in lubrication modes and friction of a range of material combinations using synthetic and biological fluids as the lubricants. The experimental results were compared with theoretical predictions of film thicknesses and lubrication modes. A strong correlation was observed between experiment and theory when employing carboxy methyl cellulose (CMC) fluids as the lubricant. Under these conditions the ceramic-on-ceramic joints showed full fluid film lubrication while the metal-on-metal, metal-on-plastic, diamond-like carbon-coated stainless steel (DLC)-on-plastic and ceramic-on-plastic prostheses operated under a mixed lubrication regime. With bovine serum as the lubricant in the all ceramic joints, however, the full fluid film lubrication was inhibited due to adsorbed proteins. In the metal-on-metal joints this adsorbed protein layer acted to reduce the friction while in the ceramic coupling the friction was increased. The use of bovine serum as the lubricant also significantly increased the friction in both the metal-on-plastic and ceramic-on-plastic joints. The friction produced by the DLC-on-plastic joints depended on the quality of the coating. Those joints with a less consistent coating and therefore a higher surface roughness gave significantly higher friction than the smoother, more consistently coated heads. PMID:11131195

Scholes, S C; Unsworth, A; Goldsmith, A A

2000-12-01

293

Alternative materials to improve total hip replacement tribology.  

PubMed

An improvement in tribology of bearing surfaces is an effective means of increasing the longevity of total hip replacement (THR). Currently, 3 approaches are available to achieve this aim: first, use of highly cross-linked UHMWPE; second, aluminum oxide ceramic bearings, and third, metal-on-metal bearings. Cross-linking reduces the wear resistance of UHMWPE markedly without impairment of other significant properties of the material. Simulator studies and some clinical long-term (10-22 years) follow-up surveys suggest an almost immeasurable wear of the highly cross-linked UHMWPE-based acetabular components during an expected clinical life span. Bioinert alumina ceramic (aluminum oxide) was introduced 3 decades ago for THR-bearing surfaces to improve performance and longevity. Alumina ceramic is entirely biostable and bioinert and has good mechanical properties. For correctly positioned alumina-on-alumina bearings, the annual linear wear rate has been reported to be 3.9 microm. Alumina heads have been successfully used in combination with polyethylene sockets, but as regards wear, the best results have been obtained with alumina-on-alumina bearings. In ceramic THR bearings, precise manufacture and contact surface geometry, including optimal clearance, are most important. For the currently available products, the component fracture risk is almost nonexistent (less than 1 per 1000). Metal-on-metal bearings were used in the early stage of THR surgery, although not all old designs were successful. More recent analyses of the early series have shown the advantages of metal-on-metal to be better and have led to a renaissance of this articulation. Initially, stainless steel was used because it was easy to manufacture and polish. Current metal-on-metal bearings are based on cobalt-chromium-molybdenum alloys with varying carbon contents. Such bearings are self-polishing. Linear wear rates remain at the level of a few microm a year. An improvement in technology has increased the life span of the above three THR-bearing systems. Although the technical solutions differ considerably, they all seem to improve clearly the tribology and longevity of the THR. Each of these bearing concepts will probably permit the use of larger head sizes, to reduce the risk of impingement and luxations. PMID:14521286

Santavirta, Seppo; Böhler, Max; Harris, William H; Konttinen, Yrjö T; Lappalainen, Reijo; Muratoglu, Orhun; Rieker, Claude; Salzer, Martin

2003-08-01

294

Cushion Form Bearings in Total Hip Arthroplasty: Nature’s Approach to the Synovial Joint Problem  

Microsoft Academic Search

\\u000a Over the past 40 years, metal-on-polyethylene bearings have been the most extensively used in total hip replacement. These\\u000a implants do not permit lubrication, and wear of the articulating surfaces occurs as a consequence. Ceramic-on-ceramic bearings\\u000a are associated with squeaking and the potential risk of breakage. Furthermore, the ceramic head is smaller than the patient’s\\u000a original head size. With metal-on-metal bearings,

Antonio Moroni; Martha Hoque; Giovanni Micera; Riccardo Orsini; Emanuele Nocco; Sandro Giannini

295

Inflammatory pseudotumor complicating metal-on-highly cross-linked polyethylene total hip arthroplasty.  

PubMed

Inflammatory masses or cysts occurring in the pelvis, thigh, and gluteal regions, often mimicking infection, occasionally arise after total hip arthroplasty procedures. Inflammatory pseudotumors comprise a subgroup of these lesions. Pseudotumors have been associated with pain, rashes, instability, neuropathy, and premature loosening of prosthetic components, often leading to early and difficult revision surgery. The association between such pseudotumors and metal-on-metal bearings has led to questions regarding the performance of these bearings in hip arthroplasty. We present a case of pseudotumor requiring revision surgery, which occurred uniquely around a metal-on-highly cross-linked polyethylene bearing. PMID:21498036

Walsh, Alan J; Nikolaou, Vassilios S; Antoniou, John

2012-02-01

296

Metal ion levels in large-diameter total hip and resurfacing hip arthroplasty-Preliminary results of a prospective five year study after two years of follow-up  

PubMed Central

Background Metal-on-metal hip resurfacing is an alternative to metal-on-metal total hip arthroplasty, especially for young and physically active patients. However, wear which might be detected by increased serum ion levels is a matter of concern. Methods The aims of this preliminary study were to determine the raise of metal ion levels at 2-years follow-up in a prospective setting and to evaluate differences between patients with either resurfacing or total hip arthroplasty. Furthermore we investigated if the inclination of the acetabular component and the arc of cover would influence these findings. Therefore, 36 patients were followed prospectively. Results The results showed increments for Co and Cr in both implant groups. Patients treated with large-diameter total hip arthroplasty showed fourfold and threefold, respectively, higher levels for Co and Cr compared to the resurfacing group (Co: p?metal-on-metal hip replacement.

2012-01-01

297

Metal ion levels in total hip arthroplasty versus hip resurfacing.  

PubMed

Recent studies suggest that the tapered interface between stem and femoral head may be a substantial source of cobalt and chromium ion release after metal-on-metal (MOM) total hip arthroplasty (THA). This study compared patient ion levels after MOM hip resurfacing (HR) and MOM THA performed with identical acetabular components. 110 HRs were compared with 22 THAs. All had well-oriented components, unilateral implants, and serum ion studies beyond one year post-operatively. The HR group's median cobalt value was 1.11 ?g/L vs. 2.86 ?g/L for the THA patients. The HR group's median chromium value was 1.49 ?g/L vs. 2.94 ?g/L for THA. Significantly higher THA ion levels suggest a source of ions other than the MOM bearing itself. PMID:23618754

Johnson, Alicia J; Le Duff, Michel J; Yoon, James P; Al-Hamad, Mariam; Amstutz, Harlan C

2013-08-01

298

Early failures in total hip arthroplasty -- a changing paradigm.  

PubMed

Between 2001 and 2011, 1168 revision hip arthroplasties were reviewed for "early" failures within 5 years of the primary total hip arthroplasty (THA). 24.1% underwent revision within 5 years of index THA. Aseptic loosening, infection, instability, metallosis, and fracture were common modes of failure. In our previous report from 1986 to 2000, 33% were "early" revisions, with instability and aseptic loosening accounting for over 70% of these early failures. While the proportion of "early" revisions decreased 9% from our previous report, this rate remains alarming. The emergence of metallosis and aseptic loosening of monoblock metal on metal shells as leading causes of early failures is concerning. This report suggests caution in the early adoption of new innovations before evidence based medicine is available to justify the risk of their use. PMID:24444568

Melvin, J Stuart; Karthikeyan, Tharun; Cope, Robert; Fehring, Thomas K

2014-06-01

299

Serum metal ion exposure after total knee arthroplasty.  

PubMed

All metal implants release metal ions because of corrosion. This has been studied and debated, especially in metal-on-metal total hip arthroplasties. Total knee arthroplasty implants have large metal surface areas and therefore substantial potential for corrosion. We determined changes in serum levels of metal ions in 41 patients after cemented unconstrained total knee arthroplasty without patellar resurfacing, 18 with unilateral total knee arthroplasty (median, 66 months after surgery) and 23 patients with bilateral total knee arthroplasties (75 and 50 months after first and second surgeries, respectively). Serum concentrations of chromium, cobalt, and molybdenum were analyzed and related to the number of total knee arthroplasties and compared with those of 130 control patients without implants. The median chromium, cobalt, and molybdenum concentrations were 0.92, 3.28, and 2.55 microg/L, respectively, in the unilateral total knee arthroplasty sample and 0.98, 4.28, and 2.40 microg/L, respectively, in the bilateral total knee arthroplasty sample. We observed no difference between the serum levels in patients with unilateral and bilateral arthroplasties, but the serum levels of chromium and cobalt of both study groups were greater than those of the control group (less than 0.25 microg/L). The patients who had total knee arthroplasty had molybdenum profiles that were similar to those of the control group (median, 2.11 microg/L). PMID:17438467

Luetzner, Joerg; Krummenauer, Frank; Lengel, Attila Michael; Ziegler, Joerg; Witzleb, Wolf-Christoph

2007-08-01

300

The ceramic-on-metal coupling in total hip replacements for young patients: a review study.  

PubMed

In the last two decades the performance of total hip replacements (THR) has constantly improved, thanks largely to advances in the field of material science and technology. Although contemporary devices are clinically very reliable, some problems still need to be addressed: the wear of ultra high molecular weight polyethylene components, the release of metal ions from metal-on-metal joints, the toughness of the ceramic cups and the possibility of squeaking for ceramic-on-ceramic couplings. All these drawbacks become particularly relevant in case of THR for young and active patients, when the life expectancy of the orthopedic device is very high and the possibility of mechanical shocks is not negligible.In the last few years an innovative ceramic-on-metal tribologic coupling has been introduced in clinical use. This novel configuration represents a very promising solution to all the aforementioned issues. Ceramic-on-metal offers both the strength points of ceramic and metal surfaces, and overcomes the limits of metal-on-metal and ceramic-on-ceramic bearings. For this reason, the ceramic-on-metal coupling has become the object of investigation for several laboratory studies and has been tested in clinical trials. This review study compares the scientific outcomes of the research on ceramic-on-metal bearings, confirming that this innovative articulation has the potential to be a suitable and attractive solution for young and active patients. PMID:21607934

Cigada, Alberto; Cotogno, Giulio; Chiesa, Roberto

2011-01-01

301

Metal-on-Metal Bonding and Rebonding Revisited  

NASA Astrophysics Data System (ADS)

Density-functional calculations for a wide variety of metals show that, contrary to rebonding theory, ad-dimers do not have notably longer surface bonds than adatoms, do not reside farther above the surface, and do not meet the rebonding arguments for augmented mobility. Rebonding contributes to destabilize ad-dimers, but does not explain inherently weak ad-dimer bonds.

Bogicevic, Alexander

1999-06-01

302

Metal-On-Metal Bonding and Rebonding Revisited  

SciTech Connect

Density-functional calculations for a wide variety of metals show that, contrary to the rebonding view of adsorbate bonding, addimers do not have notably longer surface bonds than adatoms, do not reside farther above the surface, and do not meet the rebonding arguments for augmented mobility. Rebonding concepts are found to have some utility in explaining addimer stability.

Bogicevic, A.

1999-02-23

303

Metal on Metal in Resurfacing Arthroplasty: Risks or Benefits?  

Microsoft Academic Search

\\u000a At the beginning of hip endoprosthetics was the substitution of destroyed cartilage by biologigal or artificial materials.\\u000a However, successful results were only achieved after the introduction of abrasion-resistant materials in combination with\\u000a exactly matching differences of diameter (radial clearance) of head and socket. The cobalt-based alloy Vitalliun® which had\\u000a been introduced into medical therapy by dentists in 1932 was used

M. Menge

304

What do we know about taper corrosion in total hip arthroplasty?  

PubMed

Mechanically assisted crevice corrosion (MACC) at metal/metal modular junctions in which at least one of the components is fabricated from cobalt-chromium alloy, has reemerged as a potential clinically significant complication in total hip arthroplasty. The clinical manifestation of MACC may include the development of an adverse local tissue reaction (ALTR), similar to what has been described in association with metal-on-metal bearing total hip and resurfacing arthroplasty. The clinical presentation of MACC-associated ALTRs may include pain and possibly late recurrent dislocations. Abnormal metal artifact reduction sequence magnetic resonance images and elevated serum metal levels (cobalt elevations out of proportion to chromium elevations) can be helpful in the diagnosis of these MACC-associated ALTRs. PMID:24655613

Jacobs, J J; Cooper, H J; Urban, R M; Wixson, R L; Della Valle, C J

2014-04-01

305

Early metallosis-related failure after total knee replacement: a report of 15 cases.  

PubMed

Metallosis is a rare cause of failure after total knee replacement and has only previously been reported when there has been abnormal metal-on-metal contact. We describe 14 patients (15 knees) whose total knee replacement required revision for a new type of early failure caused by extensive metallosis. A modification of a cementless rotating platform implant, which had previously had excellent long-term survival, had been used in each case. The change was in the form of a new porous-beaded surface on the femoral component to induce cementless fixation, which had been used successfully in the fixation of acetabular and tibial components. This modification appeared to have resulted in metallosis due to abrasive two-body wear. The component has subsequently been recalled and is no longer in use. The presentation, investigation, and findings at revision are described and a possible aetiology and its implications are discussed. PMID:21282760

Willis-Owen, C A; Keene, G C; Oakeshott, R D

2011-02-01

306

Total protein  

MedlinePLUS

The total protein test measures the total amount of two classes of proteins found in the fluid portion of your blood. These are albumin and globulin. Proteins are important parts of all cells and tissues. ...

307

Totally James  

ERIC Educational Resources Information Center

This article presents an interview with James Howe, author of "The Misfits" and "Totally Joe". In this interview, Howe discusses tolerance, diversity and the parallels between his own life and his literature. Howe's four books in addition to "The Misfits" and "Totally Joe" and his list of recommended books with lesbian, gay, bisexual, transgender,…

Owens, Tom

2006-01-01

308

Primary musculoskeletal mycobacterium infection with large cystic masses after total hip arthroplasty.  

PubMed

Primary mycobacterial infections in the musculoskeletal system are rare with a limited number of published case reports. This report describes a case involving a primary musculoskeletal tuberculous abscess. A 62-year-old male patient who had a right total hip arthroplasty performed 8 years earlier, using metal-on-metal articulation presented with a 1-year history of non-tender masses on his right thigh. Initially, it was assumed he had metallosis. Intraoperatively, an incision into the mass was conducted which resulted in draining of a whitish-grey pus like fluid. A diagnosis of tuberculosis was confirmed with both microscopic and histological examination. The patient was treated over a course of six months with an anti-tuberculosis medication regimen following the confirmation of a solitary soft tissue tuberculosis infection. At the 24 month follow-up, the patient was asymptomatic with no relapse of the mass. PMID:22749661

Lee, Han-Jun; Kim, Kyoung-Woon; Kim, Ki Seong; Ryu, Sung Hwa; Ha, Yong-Chan

2013-02-01

309

Survivorship, patient reported outcome and satisfaction following resurfacing and total hip arthroplasty.  

PubMed

Resurfacing (RA) and total hip arthroplasty (THA) are options in the treatment of debilitating hip pathology. 381 patients that had undergone arthroplasty with a BHR RA, ASR RA, metal-on-metal (MoM) THA or ceramic-on-ceramic (CoC) THA were reviewed for satisfaction, function, health and survivorship at a median follow up of 50 months. Significantly lower survivorship for revision and reoperation was observed in the ASR group. The BHR and CoC demonstrated better outcome scores than the ASR (OHS and SAPS) and the BHR better scores than the MoM (OHS and SF12 PCS). In the short to medium term, survivorship and outcomes for the best performing RA (BHR) and THA (CoC) were comparable. There was a non-significant trend towards poorer outcome scores in the MoM THA group. PMID:23489727

Whitehouse, Michael R; Aquilina, Alexander L; Patel, Sajal; Eastaugh-Waring, Stephen J; Blom, Ashley W

2013-05-01

310

Fracture of the modular femoral neck component in total hip arthroplasty.  

PubMed

The use of modularity, specifically dual modular femoral stems, in total hip arthroplasty has increased in popularity over the past 2 decades. While offering several distinct advantages intraoperatively, the long-term success of adding a second modular junction has yet to be established. One potential complication of increasing modularity is component fracture. We present a case of modular femoral neck prosthesis fracture necessitating revision surgery to treat this complication. Careful preoperative planning during revision of these failures is essential to avoid morbidity and unnecessary subsequent revision surgeries, as demonstrated in this case. The combined effects of crevice and fretting corrosion, large-diameter femoral head, long modular neck, metal-on-metal articulation, patient size, and activity level may have all played integral roles in creating an environment susceptible to this classic pattern of fatigue fracture. PMID:21798696

Ellman, Michael B; Levine, Brett R

2013-01-01

311

Metal allergy in patients with total hip replacement: a review.  

PubMed

Metal-on-metal prostheses are increasingly and widely used in total hip arthroplasty, and offer particular benefit to patients with osteoarthritis. Adverse effects related to the release of metal ions (such as cytotoxicity, genotoxicity, carcinogenicity and metal allergy) are common, however. The aims of this review article were to explore the relationship between corrosion products and implant-related hypersensitivity, define normal and toxic metal ion concentrations, and differentiate between allergy and infection in painful total hip replacement. The simultaneous presence of corrosion products and hypersensitivity-related tissue reactions indicates a relationship between the development of corrosion and implant-related hypersensitivity. There are no clear boundaries between normal and toxic metal ion concentrations. Several methods exist for the differential diagnosis of metal allergy and infection, including ultrasound-guided aspiration, patch testing and arthroscopic biopsy. More research is required to elucidate fully the relationship between metal articulations and allergy, and to determine the concentrations of metal ions that lead to harmful effects. PMID:23569024

Zeng, Yirong; Feng, Wenjun

2013-04-01

312

Hard-on-Hard Total Hip Impingement Causes Extreme Contact Stress Concentrations  

PubMed Central

Background Impingement events, in addition to their role immediately proximate to frank dislocation, hold the potential to damage new-generation hard-on-hard bearings as a result of the relatively unforgiving nature of the materials and designs. Because of the higher stiffness and tighter design tolerances of metal-on-metal and ceramic implants, surgical positioning plausibly has become even more important. Questions/purposes We asked (1) whether, and under what cup orientation conditions, hard-on-hard impingements might challenge implant material failure strength; and (2) whether particle generation propensity at impingement and egress sites would show similar dependence on cup orientation. Methods Realistic computational simulations were enabled by multistage finite element analyses, addressing both global construct motion and loading, and focal stress concentrations at neck impingement and rim egress sites. The global model, validated by a cadaveric simulation in a servohydraulic hip simulator, included both hardware components and advanced anisotropic capsule characterization. Parametric computational runs explored the effect of cup orientation for both ceramic-on-ceramic and metal-on-metal bearing couples for two distinct motion sequences associated with dislocation. Results Stress concentrations from impingement increased nearly linearly with increased cup tilt and with cup anteversion. In some situations, peak values of stress approached or exceeded 1 GPa, levels challenging the yield strength of cobalt-chromium implants, and potentially the fracture strength of ceramics. The tendency for impingement events to generate debris, indexed in terms of a new scraping severity metric, showed orientation dependences similar to that for bulk material failure. Conclusions Damage propensity arising from impingement events in hard total hip bearings is highly orientation-dependent.

Elkins, Jacob M.; O'Brien, Megan K.; Stroud, Nicholas J.; Pedersen, Douglas R.; Callaghan, John J.

2010-01-01

313

Pseudotumor associated with metal-on-polyethylene total hip arthroplasty.  

PubMed

This case report details the presentation, imaging results, and operative findings of a pseudotumor associated with a press-fit metal-on-polyethylene total hip arthroplasty (THA). An 80-year-old man presented approximately 7 years after undergoing THA with worsening right groin and lateral hip pain with an associated proximal thigh mass. Physical examination demonstrated a tender, large anterolateral thigh mass that was also evident on metal artifact reduction sequence magnetic resonance imaging.An exploratory operative procedure revealed extensive tissue necrosis involving nearly the entire hip capsule, short external rotators, and tendinous portion of the gluteus medius muscle. In addition, marked surface corrosion was discovered about the taper at the head-neck junction of the prosthetic femoral component and the trunnion within the femoral head. The press-fit THA components were solidly fixed. The metallic head was replaced with a ceramic component, and the polyethylene liner was exchanged. The patient had complete resolution of his preoperative symptoms but had persistent problems with dislocations.Although reports of pseudotumor and local soft tissue reactions associated with metal-on-metal THAs have become increasingly ubiquitous in the literature, similar reports involving metal-on-polyethylene THA implants are less common. PMID:23672921

Scully, William F; Teeny, Steven M

2013-05-01

314

A painful soft tissue mass secondary to impingement of a metal on polyethylene bearing total hip arthroplasty.  

PubMed

A 60-year-old woman underwent a metal on polyethylene total hip replacement. The patient experienced pain and sustained multiple dislocations over the following 2?years and was referred for consideration of revision surgery. At the time of revision surgery it was found that there was a significant amount of polyethylene wear likely to have arisen as a result of the neutral cup placement and subsequent anterior impingement. A large cystic mass was excised and on histology was found to contain tissue with a lymphocytic infiltrate with a large amount of intracellular birefringent debris, consistent with polyethylene. The appearance of such masses is well reported as pseudotumours in metal-on-metal hip replacements but as yet their aetiology is unknown. We believe that the formation of the mass in this case could represent a model by which these pseudotumours occur. PMID:24849627

William, Griffiths-Jones; Daniel, Williams

2014-01-01

315

Alumina-on-alumina total hip replacement for femoral neck fracture in healthy patients  

PubMed Central

Background Total hip replacement is considered the best option for treatment of displaced intracapsular fractures of the femoral neck (FFN). The size of the femoral head is an important factor that influences the outcome of a total hip arthroplasty (THA): implants with a 28 mm femoral head are more prone to dislocate than implants with a 32 mm head. Obviously, a large head coupled to a polyethylene inlay can lead to more wear, osteolysis and failure of the implant. Ceramic induces less friction and minimal wear even with larger heads. Methods A total of 35 THAs were performed for displaced intracapsular FFN, using a 32 mm alumina-alumina coupling. Results At a mean follow-up of 80 months, 33 have been clinically and radiologically reviewed. None of the implants needed revision for any reason, none of the cups were considered to have failed, no dislocations nor breakage of the ceramic components were recorded. One anatomic cementless stem was radiologically loose. Conclusions On the basis of our experience, we suggest that ceramic-on-ceramic coupling offers minimal friction and wear even with large heads.

2011-01-01

316

Alternative bearing surface options for revision total hip arthroplasty.  

PubMed

Despite the overall success of total hip arthroplasty (THA), there has been an increase in the rate of revision hip surgeries performed each year in the United States. These revision surgeries result in several billion dollars in health care costs. Bearing surface wear can result in the need for revision surgery through a variety of mechanisms. Many implant failures necessitating the need for revision surgeries occur secondary to dislocations, which are often related to prothesis wear and eventual loosening of the components. Wear also can lead to osteolysis and may play a role in aseptic loosening. Specific concerns regarding the wear rates of metal-on-polyethylene (the most common bearing surface) have encouraged the manufacture of newer polyethylene implants with improved wear properties, as well as alternative bearing surfaces. The goal is to improve the durability of revision implants and/or reduce the incidence of revision THAs. Revision arthroplasty involves using alternative surfaces, such as replacing the metal femoral head with a ceramic component or changing the entire prosthesis to a metal-on-metal or ceramic-on-ceramic articulation. It is important to review the characteristics of these alternative bearing surface options and their contributions to improved THA tribology and prolonged prosthesis longevity. The choice of a bearing surface for a revision THA should consider factors such as the patient's age and activity level, the cost of the implant, and both the surgeons' and patients' preferences. Although laboratory studies and small clinical trials have generated optimistic results for these alternative implants in vitro and in vivo, much still needs to be learned about the long-term performance of these materials in patients after total hip revision surgery. PMID:21553778

Patel, Deepan; Parvizi, Javad; Sharkey, Peter F

2011-01-01

317

Inertial navigator error models for large heading uncertainty  

Microsoft Academic Search

This paper is concerned with the development of a modified ?-angle error model for a strapdown inertial navigator whose platform azimuth is completely unknown, as would be the case during initial coarse heading alignment. The paper is a review of the author's (1994) previous paper, and provides a framework for developing large azimuth uncertainty error models. It then presents the

Bruno M. Scherzinger

1996-01-01

318

TETE: Total Education in the Total Environment.  

ERIC Educational Resources Information Center

The Hudson River Museum's Environmental Arts and Science Division has published this booklet describing their model educational program, "TETE: Total Education in the Total Environment," a multidisciplinary approach to environmental education utilizing existing curricula. For conducting the program model communities strategically located along the…

Eblen, William R.

319

New insights into hard phases of CoCrMo metal-on-metal hip replacements.  

PubMed

The microstructural and mechanical properties of the hard phases in CoCrMo prosthetic alloys in both cast and wrought conditions were examined using transmission electron microscopy and nanoindentation. Besides the known carbides of M(23)C(6)-type (M=Cr, Mo, Co) and M(6)C-type which are formed by either eutectic solidification or precipitation, a new mixed-phase hard constituent has been found in the cast alloys, which is composed of ?100 nm fine grains. The nanosized grains were identified to be mostly of M(23)C(6) type using nano-beam precession electron diffraction, and the chemical composition varied from grain to grain being either Cr- or Co-rich. In contrast, the carbides within the wrought alloy having the same M(23)C(6) structure were homogeneous, which can be attributed to the repeated heating and deformation steps. Nanoindentation measurements showed that the hardness of the hard phase mixture in the cast specimen was ?15.7 GPa, while the M(23)C(6) carbides in the wrought alloy were twice as hard (?30.7 GPa). The origin of the nanostructured hard phase mixture was found to be related to slow cooling during casting. Mixed hard phases were produced at a cooling rate of 0.2 °C/s, whereas single phase carbides were formed at a cooling rate of 50 °C/s. This is consistent with sluggish kinetics and rationalizes different and partly conflicting microstructural results in the literature, and could be a source of variations in the performance of prosthetic devices in-vivo. PMID:22659365

Liao, Y; Pourzal, R; Stemmer, P; Wimmer, M A; Jacobs, J J; Fischer, A; Marks, L D

2012-08-01

320

Information for Patients Who Have Metal-on-Metal Hip Implants  

MedlinePLUS

... physical activity What should I do if I am experiencing adverse events associated with my metal-on- ... their evaluation. What should I do if I am not experiencing adverse events associated with my metal- ...

321

Dendritic islands in metal-on-metal epitaxy II. Coalescence and multilayer growth  

NASA Astrophysics Data System (ADS)

Dendritic or fractal islands occur naturally during epitaxial growth in systems where island edge diffusion is restricted. Here we use a lattice-gas model to characterize the evolution of island structure in such systems, from the low coverage to the coalescence regime, and to consider the ramifications for multilayer growth. Island densification and slowing of radial growth prior to coalescence is observed in the simulations, as in Au/Ru(0001). We also elucidate the relationship of the real-space island structure to the width and shape of the corresponding kinematic diffraction profile. Our multilayer growth studies incorporate disruption of and downward funneling from island edges upon impact of depositing atoms, in the presence of a large Schwoebel barrier. Using the geometry and length scales appropriate for Pt/Pt(111), the calculated kinematic Bragg intensities for a two-layer model show that even limited disruption can produce the observed low-temperature "reentrant" oscillations.

Bartelt, M. C.; Evans, J. W.

1994-07-01

322

Open surface dynamics of atoms and dimers in metal-on-metal growth  

NASA Astrophysics Data System (ADS)

We present a detailed first-principles mapping of ad-dimer diffusion and dissociation by hopping on the open (100) surfaces of Al, Au, and Rh. Diffusion is found to proceed by shearing, because it maximizes adatom coordination at the transition state. As geometrical aspects are found to dominate over details of the electronic structure, our results are likely to be generally valid for fcc metals. Further, over a dozen computed activation energies are rationalized in a pair-wise model based on two fundamental quantities, the adatom diffusion barrier and the dimer binding energy, which should greatly facilitate parametrization in kinetic simulations. In conjunction with these results, the issue of diffusion by exchange with the substrate is discussed.

Ovesson, Staffan; Bogicevic, Alexander; Lundqvist, Bengt I.; Jennison, Dwight R.

2000-03-01

323

Origin of Compact Triangular Islands in Metal-on-Metal Growth  

NASA Astrophysics Data System (ADS)

The microscopic origin of compact triangular islands on close-packed surfaces is identified using kinetic Monte Carlo simulations with energy barriers obtained from density-functional calculations. In contrast to earlier accounts, corner diffusion anisotropy is found to control the shape of compact islands at intermediate temperatures. We rationalize the correlation between the orientation of dendrites grown at low temperatures and triangular islands grown at higher temperatures, and explain why in some systems dendrites grow fat before turning compact.

Ovesson, Staffan; Bogicevic, Alexander; Lundqvist, Bengt I.

1999-09-01

324

High-speed, high-load, metal-on-metal friction.  

NASA Astrophysics Data System (ADS)

The physical processes of deformation at the interface between two metals moving relative to one another at high speeds, approaching significant fractions of the material sound speeds, are not well known. Preliminary issues relating to a combined experimental and theoretical/numerical program to characterize the interfacial dynamics of metal-to-metal interfaces at high speeds and loads will be presented. Velocity weakening of the frictional force as a function of increasing relative velocities has been observed in earlier investigations, usually for modest normal loading, although data in this regime is sparse. Recent large-scale atomistic molecular dynamics simulations have shown a similar decrease in the coefficient of friction for smooth copper interfaces at high relative velocities. To gain further insight into the physics of slip at strongly driven interfaces, we have begun an experimental program to characterize dry sliding between metals in the velocity, load regime of 0 -- 1 km/s and 0 -- 100 kbar. Interfacial conditions, force histories and hysteresis effects for each of these geometries will be discussed.

Rightley, Paul; Pelak, Robert; Hammerberg, Jim; Benjamin, Robert

1998-04-01

325

Sex as a Patient Selection Criterion for Metal-on-Metal Hip Resurfacing Arthroplasty  

Microsoft Academic Search

Short-term to midterm results of hip resurfacing arthroplasty suggest various contraindications, in particular the female sex. This study evaluates survivorship and clinical outcomes of a large patient cohort to determine whether sex itself has a detrimental effect on the results of hip resurfacing. We compared the clinical and survivorship results of men and women from a series of 1107 resurfaced

Harlan C. Amstutz; Lauren E. Wisk; Michel J. Le Duff

2011-01-01

326

Cementing the Metaphyseal Stem in Metal-on-Metal Resurfacing: When and Why  

Microsoft Academic Search

Initial fixation of the femoral component in hip resurfacing is key to the enduring survival of the prosthesis. Cementing\\u000a the metaphyseal stem increases the interface area between bone and cement. We compared the clinical and survivorship results\\u000a of two groups in a cohort of 1000 hips (838 patients) implanted with Conserve® Plus hip resurfacing; one group was resurfaced with a

Harlan C. Amstutz; Michel J. Le Duff

2009-01-01

327

Impingement as a Mechanism of Dissociation of a Metasul Metal-on-Metal Liner  

Microsoft Academic Search

This case report is of a patient with disassociation of the acetabular cup liner caused by impingement. The cup inclination (39°) and anteversion (24°) were good as measured by computer navigation. Impingement occurred because the head-neck ratio was 2.0, and the hip length and offset were short by one head length. Successful revision without intraoperative impingement was accomplished with one

Aamer Malik; Lawrence D. Dorr; William T. Long

2009-01-01

328

Early Osteolysis Following Second-Generation Metal-on-Metal Hip Replacement  

Microsoft Academic Search

Results: The patients with early osteolysis had a significantly higher rate of hypersensitivity reaction to cobalt com- pared with controls (p = 0.031). The retrieved periprosthetic tissues showed no evidence of metallic staining, but his- tologic analysis revealed a perivascular accumulation of CD3-positive T-cells and CD68-positive macrophages and an absence of both particle-laden macrophages and polymorphonuclear cells. Immunohistochemical analysis demon-

YOUN-SOO PARK; YOUNG-WAN MOON; SEUNG-JAE LIM; JUN-MO YANG; GEUNGHWAN AHN; YOON-LA CHOI

329

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

PubMed

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. PMID:24462265

Myant, Connor; Cann, Philippa

2014-06-01

330

Friction moments of large metal-on-metal hip joint bearings and other modern designs  

Microsoft Academic Search

Modern hip joint replacements are designed to minimise wear problems. The most popular metal-on-polyethylene components are being updated by harder metal and ceramic combinations. However, this has also been shown to influence the friction moments, which could overload the interface between the implant and the body. In this study custom test apparatus was used to measure the joint moments in

N. E. Bishop; F. Waldow; M. M. Morlock

2008-01-01

331

New Insights into Hard Phases of CoCrMo Metal-on-Metal Hip Replacements  

PubMed Central

The microstructural and mechanical properties of the hard phases in CoCrMo prosthetic alloys in both cast and wrought conditions were examined using transmission electron microscopy and nanoindentation. Besides the known carbides of M23C6-type (M=Cr, Mo, Co) and M6C-type which are formed by either eutectic solidification or precipitation, a new mixed-phase hard constituent has been found in the cast alloys, which is composed of ~100 nm fine grains. The nanosized grains were identified to be mostly of M23C6 type using nano-beam precession electron diffraction, and the chemical composition varied from grain to grain being either Cr- or Co-rich. In contrast, the carbides within the wrought alloy having the same M23C6 structure were homogeneous, which can be attributed to the repeated heating and deformation steps. Nanoindentation measurements showed that the hardness of the hard phase mixture in the cast specimen was ~15.7 GPa, while the M23C6 carbides in the wrought alloy were twice as hard (~30.7 GPa). The origin of the nanostructured hard phase mixture was found to be related to slow cooling during casting. Mixed hard phases were produced at a cooling rate of 0.2 °C/s, whereas single phase carbides were formed at a cooling rate of 50 °C/s. This is consistent with sluggish kinetics and rationalizes different and partly conflicting microstructural results in the literature, and could be a source of variations in the performance of prosthetic devices in-vivo.

Liao, Y.; Pourzal, R.; Stemmer, P.; Wimmer, M.A.; Jacobs, J.J.; Fischer, A.; Marks, L. D.

2012-01-01

332

Current status of modern fully porous coated metal-on-metal hip resurfacing arthroplasty.  

PubMed

Between March 2007 and July 2010, 1000 consecutive fully porous coated hip resurfacing arthroplasties (HRA) were performed by a single surgeon in 871 patients. The average length of follow-up was 3 ± 1 years. Three cases (0.3%) in three patients showed adverse wear related failures. Another 17 (1.7%) failures were identified at the time of this study. Using any failure of any component as the endpoint, the survivorship rate was 98.8% at two years and 97.4% at five years. Excluding the failed cases, all components were radiographically stable; there was only one partial femoral radiolucency seen. The clinical and radiological outcomes of this fully porous coated hip resurfacing were comparable to, if not better than, those reported by others using hybrid fixation methods at five years post-operatively. PMID:23680504

Gross, Thomas P; Liu, Fei

2014-01-01

333

Metal release and metal allergy after total hip replacement with resurfacing versus conventional hybrid prosthesis.  

PubMed

Background - Metal-on-metal (MOM) total hip arthroplasties were reintroduced because of the problems with osteolysis and aseptic loosening related to polyethylene wear of early metal-on-polyethylene (MOP) arthroplasties. The volumetric wear rate has been greatly reduced with MOM arthroplasties; however, because of nano-size wear particles, the absolute number has been greatly increased. Thus, a source of metal ion exposure with the potential to sensitize patients is present. We hypothesized that higher amounts of wear particles result in increased release of metal ions and ultimately lead to an increased incidence of metal allergy. Methods - 52 hips in 52 patients (median age 60 (51-64) years, 30 women) were randomized to either a MOM hip resurfacing system (ReCap) or a standard MOP total hip arthoplasty (Mallory Head/Exeter). Spot urine samples were collected preoperatively, postoperatively, after 3 months, and after 1, 2, and 5 years and tested with inductively coupled plasma-sector field mass spectrometry. After 5 years, hypersensitivity to metals was evaluated by patch testing and lymphocyte transformation assay. In addition, the patients answered a questionnaire about hypersensitivity. Results - A statistically significant 10- to 20-fold increase in urinary levels of cobalt and chromium was observed throughout the entire follow-up in the MOM group. The prevalence of metal allergy was similar between groups. Interpretation - While we observed significantly increased levels of metal ions in the urine during the entire follow-up period, no difference in prevalence of metal allergy was observed in the MOM group. However, the effect of long-term metal exposure remains uncertain. PMID:24930546

Gustafson, Klas; Jakobsen, Stig S; Lorenzen, Nina D; Thyssen, Jacob P; Johansen, Jeanne D; Bonefeld, Charlotte M; Stilling, Maiken; Baad-Hansen, Thomas; Søballe, Kjeld

2014-08-01

334

Total hip arthroplasty in the young: special emphasis on post-SCFE patients.  

PubMed

Slipped capital femoral epiphysis (SCFE) is a hip disorder of adolescence, which has the potential for profound implications into adulthood. SCFE patients are at risk of early joint degeneration and subsequent need for arthroplasty. The rate at which arthroplasty is required is not precisely known, but is estimated to be approximately 45% by 50 years after a slip. The femoral neck and shaft displace anteriorly and rotate externally relative to the femoral epiphysis, which remains fixed in the acetabulum. Stabilization of the physis is the goal of acute management. Despite such efforts, accelerated joint degeneration may occur over time. This progression is due to avascular necrosis, chondrolysis, or following years of femoroacetabular impingement. Total hip arthroplasty (THA) and total hip resurfacing (THR) are options for end-stage hip arthritis due to SCFE. THR is technically more challenging, with very limited ability to address deformity-related issues of impingement, decreased hip offset, and trochanteric malposition. THR, as in any metal on metal arthroplasty, may be associated with local metal sensitivity or systemic metal toxicity. Given the limited utility and potential risks, THR is currently not recommended in the majority of cases. THA, although historically demonstrating poor long-term implant performance in the young patient, has become a more reliable option recently. The potential benefits of THA are considerable, even for the young patient with end-stage hip degeneration. Certain cemented and many cementless stem designs show good long-term survival, as do current cementless cups. Advances in bearing surfaces promise to minimize wear and extend implant longevity. Ceramic on ceramic, metal on highly cross-linked polyethylene, and ceramic on highly cross-linked polyethylene bearing couples offer promise. PMID:23764787

Nelms, Nathaniel J; Lewallen, Laura W; McIntosh, Amy L; Sierra, Rafael J

2013-01-01

335

Compatibility of the totally replaced hip. Reduction of wear by amorphous diamond coating.  

PubMed

Particulate wear debris in totally replaced hips causes adverse local host reactions. The extreme form of such a reaction, aggressive granulomatosis, was found to be a distinct condition and different from simple aseptic loosening. Reactive and adaptive tissues around the totally replaced hip were made of proliferation of local fibroblast like cells and activated macrophages. Methylmethacrylate and high-molecular-weight polyethylene were shown to be essentially immunologically inert implant materials, but in small particulate form functioned as cellular irritants initiating local biological reactions leading to loosening of the implants. Chromium-cobalt-molybdenum is the most popular metallic implant material; it is hard and tough, and the bearings of this metal are partially self-polishing. In total hip implants, prerequisites for longevity of the replaced hip are good biocompatibility of the materials and sufficient tribological properties of the bearings. The third key issue is that the bearing must minimize frictional shear at the prosthetic bone-implant interface to be compatible with long-term survival. Some of the approaches to meet these demands are alumina-on-alumina and metal-on-metal designs, as well as the use of highly crosslinked polyethylene for the acetabular component. In order to avoid the wear-based deleterious properties of the conventional total hip prosthesis materials or coatings, the present work included biological and tribological testing of amorphous diamond. Previous experiments had demonstrated that a high adhesion of tetrahedral amorphous carbon coatings to a substrate can be achieved by using mixing layers or interlayers. Amorphous diamond was found to be biologically inert, and simulator testing indicated excellent wear properties for conventional total hip prostheses, in which either the ball or both bearing surfaces were coated with hydrogen-free tetrahedral amorphous diamond films. Simulator testing with such total hip prostheses showed no measurable wear or detectable delamination after 15,000,000 test cycles corresponding to 15 years of clinical use. The present work clearly shows that wear is one of the basic problems with totally replaced hips. Diamond coating of the bearing surfaces appears to be an attractive solution to improve longevity of the totally replaced hip. PMID:14768485

Santavirta, Seppo

2003-12-01

336

Total Quality Leadership  

NASA Technical Reports Server (NTRS)

More than 750 NASA, government, contractor, and academic representatives attended the Seventh Annual NASA/Contractors Conference on Quality and Productivity. The panel presentations and Keynote speeches revolving around the theme of total quality leadership provided a solid base of understanding of the importance, benefits, and principles of total quality management (TQM). The presentations from the conference are summarized.

1991-01-01

337

Why Total Hip Resurfacing  

Microsoft Academic Search

Improvements in materials and fixation have addressed many of the limitations of resurfacing total hip arthroplasty (THA). The functional demands and the longevity of arthroplasty patients are increasing. Many patients have embraced the functional capacity, bone conservation, and revision options of hip resurfacing. Young men have historically been at increased risk for failure of total THA. In this patient subgroup,

Thomas P. Schmalzried

2007-01-01

338

Total synthesis of (±)-meloscine.  

PubMed

The total synthesis of (±)-meloscine was completed in a highly stereoselective manner starting from the known 4-(2-aminophenyl)-2,3-dihydro-N-methoxycarbonylpyrrole. The crucial step in this total synthesis involves the efficient construction of the tetracyclic framework of the target natural product by the intramolecular Pauson-Khand reaction. PMID:21381682

Hayashi, Yujiro; Inagaki, Fuyuhiko; Mukai, Chisato

2011-04-01

339

Ceramic-on-metal for total hip replacement: mixing and matching can lead to high wear.  

PubMed

Ceramic-on-ceramic and metal-on-metal bearing surfaces are often employed for total hip replacement because of their resistance to wear. However, they have some limits: brittleness is a major concern for ceramic, and ion release is a drawback for metal. To reduce the effect of these limitations, a hybrid coupling of ceramic-on-metal has been proposed. The theoretical advantage of this new coupling might lead orthopedic surgeons to use it indiscriminately. We asked whether the wear rate of this innovative solution was comparable with that of ceramic-on-ceramic, which is considered to be the gold standard for wear resistance. In a hip simulator study, we tested the wear pattern of a hybrid ceramic-on-metal coupling supplied by the same distributor; in particular, three different configurations were tested for 5 million cycles: 36-mm ceramic-on-ceramic, 32-mm and 36-mm ceramic-on-metal. These combinations were gravimetrically and geometrically evaluated. After 5 million cycles, the volumetric loss for the metal acetabular cups (Phi 36-mm) was 20-fold greater than that of the ceramic cups of the same size (Phi 36-mm); a volumetric loss of 4.35 mm(3) and 0.26 mm(3) was observed, respectively, for ceramic-on-metal and ceramic-on-ceramic combinations. Significant statistical differences were observed between all 36-mm different combinations (P < 0.0001). The increased diameter of the 36-mm ceramic-on-metal configuration resulted in a lower volumetric loss compared with that of the 32-mm ceramic-on-metal configuration. Our findings showed an increase in wear for the proposed hybrid specimens with respect to that of the ceramic-on-ceramic ones. This confirms that even in the case of ceramic-on-metal bearings, mixing and matching could not prove effective wear behavior, not even comparable with that of the ceramic-on-ceramic gold standard. PMID:20420614

Affatato, Saverio; Spinelli, Michele; Zavalloni, Mara; Traina, Francesco; Carmignato, Simone; Toni, Aldo

2010-04-01

340

Total hip arthroplasty.  

PubMed Central

Total hip arthroplasty, or surgical replacement of the hip joint with an artificial prosthesis, is a reconstructive procedure that has improved the management of those diseases of the hip joint that have responded poorly to conventional medical therapy. In this review we briefly summarize the evolution of total hip arthroplasty, the design and development of prosthetic hip components, and the current clinical indications for this procedure. The possible complications of total hip arthroplasty, its clinical performance over time, and future directions in hip replacement surgery are also discussed. Images

Siopack, J S; Jergesen, H E

1995-01-01

341

Total synthesis of (+)-angelmarin.  

PubMed

An efficient 8-step enantioselective total synthesis of (+)-angelmarin, starting from commercially available umbelliferone, has been achieved. Key reactions include olefin cross-metathesis and a Shi epoxidation-cyclization sequence. PMID:19459593

Magolan, Jakob; Coster, Mark J

2009-07-17

342

Total Variation Electrocardiogram Filtering.  

National Technical Information Service (NTIS)

We examine the performance of Total Variation (TV) smoothing for processing of noisy Electrocardiogram (ECG) recorded by an ambulatory device. The TV smoothing is compared with traditionally-used bandpass filtering using ECG with artificially added noise ...

A. Gribok M. Buller R. Hoyt W. Rumpler

2011-01-01

343

Total Water Management - slides  

EPA Science Inventory

Total Water Management (TWM) examines urban water systems in an interconnected manner. It encompasses reducing water demands, increasing water recycling and reuse, creating water supply assets from stormwater management, matching water quality to end-use needs, and achieving envi...

344

Total Knee Replacement  

MedlinePLUS

... types: osteoarthritis, rheumatoid arthritis, and post-traumatic arthritis. • Osteoarthritis. This is an age-related “wear and tear” ... a smooth gliding surface. Total Knee Replacement cont. Osteoarthritis o en results in bone rubbing on bone. ...

345

Total Internal Reflection  

NSDL National Science Digital Library

In this activity, learners use a laser pointer, empty soda bottle, rubber plug and water to demonstrate total internal reflection. Use this simple activity as a demonstration or group activity to explore reflection, refraction, fiber optics, and Snell's Law. This resource contains background information about total internal reflection, the equation for Snell's Law, and refractive indexes as well as links to articles about reflection and refraction of light.

America, Optical S.

2008-01-01

346

Total Health Organization.  

PubMed

Total Health Organization is a holistic care an humanitarian relief agency with special emphasis on Africa and Third World countries. It was founded in 1987 with a focus on hunger relief, health assistance, handicap, habitat and human rights of destitutes, socially disadvantaged persons and communities which it has adopted as the socially forgotten people (SFP). Total Health Organization is a non-political, non-profit, and international non-governmental organization, having official relations with several national, regional and world bodies. Some of the project activities include: free mobile clinics to rural destitutes, AIDS and related health education, an information and research library, and an NGO Development Center. For more information, please contact: Dr. Obi Osisiogu, Founder and President, Total Health International Center, 147 Ikot-Ekpene Road, P.O. Box 1726, Aba, Abia State Nigeria, Tel: 082-222279, Telex: 63311 ANYA NG, Fax: 234-82-227512. PMID:12159248

1993-01-01

347

[Total joint arthroplasty].  

PubMed

Control of the disease activity is enabled due to the progress of drug therapy for rheumatoid arthritis. However, surgical treatments are necessary for unresponsive cases to the drug or for achieving higher QOL, and we can attain more tight control or cure by combination of drug therapy and surgical treatments. Total joint arthroplasty provides indolence, mobility, stability and is an useful joint reconstruction method. Shoulder and elbow joint work as a reach function together, and total joint arthroplasty become adaptation when extensive joint destruction or severe pain occurrs. With the usage of biologic agents joint repair is possible in small joints, but if the joint destruction progress in weight-bearing joints, repair is impossible and total joint arthroplasty can be required. PMID:23961679

Mibe, Junya; Yamamoto, Kengo

2013-07-01

348

Total Energy Monitor  

SciTech Connect

The total energy monitor (TE) is a thermal sensor that determines the total energy of each FEL pulse based on the temperature rise induced in a silicon wafer upon absorption of the FEL. The TE provides a destructive measurement of the FEL pulse energy in real-time on a pulse-by-pulse basis. As a thermal detector, the TE is expected to suffer least from ultra-fast non-linear effects and to be easy to calibrate. It will therefore primarily be used to cross-calibrate other detectors such as the Gas Detector or the Direct Imager during LCLS commissioning. This document describes the design of the TE and summarizes the considerations and calculations that have led to it. This document summarizes the physics behind the operation of the Total Energy Monitor at LCLS and derives associated engineering specifications.

Friedrich, S

2008-08-11

349

Head size and dislocation rate in primary total hip arthroplasty  

PubMed Central

Background: Dislocation after total hip arthroplasty (THA) has a multifactorial etiology with variables such as surgical approach, component orientation and position, type of cup, stem and head size. Review of the literature regarding the relationship of head size and dislocation rate in THA is suggestive that large femoral head size is associated with lower dislocation rate after THA. However, limited data is available as a proof of this hypothesis. The purpose of this study was to determine that the use of large head size would lead to a decreased incidence of dislocations following THA. Materials and Methods: 317 primary THAs were performed using the posterolateral approach with posterior soft-tissue repair between January 2006 and December 2009. Cases were divided into two groups (A and B). Femoral head diameter size 36 mm was used in 163 THA in group A and 28 mm in 154 THA in group B. Average period of followup being 2 years (6 month to 4 years). Patients were routinely followed at definite intervals and were specifically assessed for dislocation. Results: One or more dislocations occurred in 11 out of 317 hips with the overall rate of dislocation being 3.47%. Dislocation rate was 0.6% in 36 mm head size and 6.49% with 28 mm head size (P value is 0.0107). Keeping the stem design variable as a constant, the difference in the rate of dislocation between the two groups was again found to be statistically significant for both un-cemented and cemented stem. Conclusion: Dislocation rate decreased significantly as the size of the head increased in primary THA. However, longer followup is necessary as rate of dislocation or in vivo highly cross linked poly failure or fracture may increase in future affecting the rate of dislocations in primary THA.

Singh, Somesh P; Bhalodiya, Haresh P

2013-01-01

350

Total pelvic mesh repair  

Microsoft Academic Search

INTRODUCTION: This report describes our technique and experience in restoring the pelvic floor of females with pelvic organ prolapse. METHODS: Total pelvic mesh repair uses a strip of Marlex Mesh® secured between the perineal body and the sacrum. Two additional strips, attached to the first, are tunneled laterally to the pubis and support the vagina and bladder laterally. Candidates for

Eugene S. Sullivan; Christopher J. Longaker; Patrick Y. H. Lee

2001-01-01

351

A Total Solar Eclipse  

NSDL National Science Digital Library

The representation depicts a total solar eclipse with a static diagram showing the moon positioned between the sun and Earth. The point where the shadow cone reaches the Earth is labeled with an arrow stating it as the "eclipse path." The umbra and penumbra are also labeled.

352

TOTAL DIET STUDY  

EPA Science Inventory

The Total Diet Study (TDS), sometimes called the Market Basket Study, is an ongoing FDA program that determines levels of various pesticide residues, contaminants, and nutrients in foods, for the purpose of estimating intakes of these substances in representative diets of specifi...

353

Total synthesis of (±)-davanone  

Microsoft Academic Search

The total synthesis of the sesquiterpene (±)-davanone is described. A Lewis acid catalyzed [3+4] annulation reaction of 1,4-pentanedione with bis(trimethylsilyl) enol ether 2 is the key synthetic step. The resulting oxabicyclo[3.2.1]heptanone system can be selectively ring-opened and then elaborated further to (±)-davanone.

Gary A. Molander; Julia Haas

1999-01-01

354

Total Synthesis of Brevisamide  

PubMed Central

The second total synthesis of Brevisamide, a marine cyclic ether alkaloid from Karenia brevis is reported. This streamlined synthesis proceeds in 21 steps, 14 steps longest linear sequence, in 5.2% overall yield and features a key SmI2 reductive cyclization step to access the tetrasubstituted pyran core.

Fadeyi, Olugbeminiyi O.; Lindsley, Craig W.

2010-01-01

355

Total Quality Education.  

ERIC Educational Resources Information Center

The impetus and focus of quality improvement efforts in higher education are examined, and a corporate grant program supporting the use of total quality management strategies in optometric education is described. Subsequent articles on grant-supported projects are previewed. (MSE)

Schornack, Julie

1996-01-01

356

CSF total protein  

MedlinePLUS

CSF total protein is a test to determine the amount of protein in your spinal fluid, also called cerebrospinal fluid (CSF). ... The normal protein range varies from lab to lab, but is typically about 15 to 60 mg/dL. Note: mg/dL = ...

357

Total Synthesis of Kopsinine  

PubMed Central

The use of a powerful intramolecular [4 + 2]/[3 + 2] cycloaddition cascade of an 1,3,4-oxadiazole in the divergent total synthesis of kopsinine (1), featuring an additional unique SmI2-promoted transannular cyclization reaction for formation of the bicyclo[2.2.2]octane central to its hexacyclic ring system, is detailed.

Xie, Jian; Wolfe, Amanda L.; Boger, Dale L.

2013-01-01

358

Total Quality Management Seminar.  

ERIC Educational Resources Information Center

This booklet is one of six texts from a workplace literacy curriculum designed to assist learners in facing the increased demands of the workplace. The booklet contains seven sections that cover the following topics: (1) meaning of total quality management (TQM); (2) the customer; (3) the organization's culture; (4) comparison of management…

Massachusetts Career Development Inst., Springfield.

359

Total Water Management - Report  

EPA Science Inventory

There is a growing need for urban water managers to take a more holistic view of their water resource systems as population growth, urbanization, and current operations put different stresses on the environment and urban infrastructure. Total Water Management (TWM) is an approac...

360

Total syntheses of echinopines.  

PubMed

A concise and scalable synthesis of a cis-fused bicyclo[5.3.0]decane ring system has been developed for the total synthesis of echinopines. The core of the natural products was constructed efficiently through an intramolecular 1,3-dipolar cycloaddition and ring contraction strategy. PMID:23540437

Xu, Wenbo; Wu, Shuming; Zhou, Lili; Liang, Guangxin

2013-04-19

361

Total Productive Maintenance  

NSDL National Science Digital Library

Created by Kaye Krueger of Wisconsin Online Resource Center, this presentation allows user to read about how total productive maintenance can prevent breakdowns, defects, and a variety of other losses. This is a nice brief introduction to this important topic in manufacturing engineering.

Krueger, Kaye

2010-09-24

362

Total Energy CMR Production.  

National Technical Information Service (NTIS)

The following outlines the optimized pulsed laser deposition (PLD) procedure used to prepare Nd(sub 0.67)Sr(sub 0.33)MnO(sub 3) (NSMO) temperature sensors at Towson University (Prof. Rajeswari Kolagani) for the LCLS XTOD Total Energy Monitor. The samples ...

R. M. Kolagani S. Friedrich

2008-01-01

363

Total Precipitable Water  

SciTech Connect

The simulation was performed on 64K cores of Intrepid, running at 0.25 simulated-years-per-day and taking 25 million core-hours. This is the first simulation using both the CAM5 physics and the highly scalable spectral element dynamical core. The animation of Total Precipitable Water clearly shows hurricanes developing in the Atlantic and Pacific.

None

2012-01-01

364

Total Synthesis of (+)-Asperazine  

PubMed Central

The first total synthesis of the structurally novel cyclotryptophan alkaloid asperazine is reported. The central step in the synthetic sequence is a diastereoselective intramolecular Heck reaction in which the substituent controlling stereoselection is external to the ring being formed. This synthesis confirmed the structure of (+)-asperazine (1) proposed by Crews and co-workers and provided material for additional biological studies. The in vitro cytotoxicity originally reported for the marine isolate was not confirmed with synthetic (+)-asperazine.

Govek, Steven P.; Overman, Larry E.

2007-01-01

365

Total variation blind deconvolution  

Microsoft Academic Search

We present a blind deconvolution algorithm based on the total variational (TV) minimization method proposed by Acar and Vogel (1994). The motivation for regularizing with the TV norm is that it is extremely effective for recovering edges of images as well as some blurring functions, e.g., motion blur and out-of-focus blur. An alternating minimization (AM) implicit iterative scheme is devised

Tony F. Chan; Chiu-Kwong Wong

1998-01-01

366

Total synthesis of (-)-borrelidin.  

PubMed

The total synthesis of borrelidin has been achieved. The best feature of our synthetic route is SmI(2)-mediated intramolecular Reformatsky-type reaction for macrocyclization after esterification between two segments. The two key segments were synthesized through chelation-controlled carbotitanation, chelation-controlled hydrogenation, stereoselective Reformatsky reaction, and MgBr(2).Et(2)O-mediated chelation-controlled allylation. [reaction: see text] PMID:15151434

Nagamitsu, Tohru; Takano, Daisuke; Fukuda, Takeo; Otoguro, Kazuhiko; Kuwajima, Isao; Harigaya, Yoshihiro; Omura, Satoshi

2004-05-27

367

Total hypopharyngeal reconstruction.  

PubMed

In advanced hypopharyngeal carcinoma, the tumor may involve the entire hypopharyngeal mucosa and the larynx. After total laryngohypopharyngectomy is done, reconstruction of the circumferential defect of the hypopharynx is a challenge. We described our results of using a myomucosal tongue flap with dermal or skin graft (MTF) in 8 patients and using a tubed pectoralis major myocutaneous flap (TPMF) in 10 patients to reconstruct the total hypopharynx. There was no operative mortality. Fistula formation occurred in 3 patients of the MTF group and 4 in the TPMF group but all had spontaneous healing after conservative treatment. One in the MTF group and 4 in the TPMF group had stenosis of the anastomotic sites. Almost all responded well with periodic dilatation. Only one patient in the TPMF group who had been previously irradiated required gastrostomy for feeding. The 5-year actuarial survival rate of our patients was 32 per cent. These results show that total hypopharynx can be reconstructed with the above noted procedures. The survival rate is good, the morbidity rate is acceptable, and the perioperative mortality rate is zero. PMID:11560208

Sittitrai, P; Pattarasakulchai, T

2001-05-01

368

Physician Update: Total Health  

PubMed Central

As an integrated prepaid health care system, Kaiser Permanente (KP) is in a unique position to demonstrate that affordability in health care can be achieved by disease prevention. During the past decade, KP has significantly improved the quality care outcomes of its members with preventable diseases. However, because of an increase in the incidence of preventable disease, and the potential long-term and short-term costs associated with the treatment of preventable disease, KP has developed a new strategy called Total Health to meet the current and future needs of its patients. Total Health means healthy people in healthy communities. KP’s strategic vision is to be a leader in Total Health by making lives better. KP hopes to make lives better by 1) measuring vital signs of health, 2) promoting healthy behaviors, 3) monitoring disease incidence, 4) spreading leading practices, and 5) creating healthy environments with our community partners. Best practices, spread to the communities we serve, will make health care more affordable, prevent preventable diseases, and save lives.

Tuso, Phillip

2014-01-01

369

Chronic total coronary occlusions.  

PubMed

Chronic total coronary occlusions (CTO) occur in up to one-third of patients undergoing coronary angiography. Indications for opening CTOs include relief of angina, improving left ventricular function, decreasing the need for coronary artery bypass surgery, and improved long-term survival. Newer technology, wire-based and non-wired-based, has improved the ability to cross these previously uncrossable lesions, thereby improving the acute success rates of opening these lesions. Also, the advent of drug-eluting stents has markedly increased the long-term patency of these complex lesions. Therefore, the clinical demand for opening these chronically occluded arteries has increased. PMID:16781941

Braden, Gregory A

2006-05-01

370

Total synthesis of lodopyridone.  

PubMed

A convergent total synthesis of the structurally unprecedented alkaloid lodopyridone was achieved using a cross-coupling of an iodopyridone fragment with a quinolinethiazolylstannane. Key features of the syntheses of the pentasubstituted 4-pyridone were a regioselective bromination of a 4-pyridone derived from kojic acid, a subsequent Cu-mediated introduction of the thioether, and a directed lithiation/iodination step. A chemoselective Negishi cross-coupling of a dibromothiazole and a quinolinylzinc reagent was used to assemble the chloroquinolinethiazol moiety. PMID:22909023

Burckhardt, Tobias; Harms, Klaus; Koert, Ulrich

2012-09-01

371

Total synthesis of (+)-crotogoudin.  

PubMed

Fellowship of the ring: The first total synthesis of (+)-crotogoudin, a 3,4-seco-atisane diterpenoid natural product, is reported. Asymmetric access to the bicyclo[2.2.2]octane core is achieved through a desymmetrization of a meso-diketone with baker's yeast (LG=leaving group, PG=protecting group). A SmI2 -induced radical cyclopropane-opening/annulation/elimination cascade affords the suitably decorated tetracyclic structure of (+)-crotogoudin. The synthesis led to revision of the reported optical rotation of the natural product and to assignment of its absolute configuration as an ent-atisane (5R,10R). PMID:24039092

Breitler, Simon; Carreira, Erick M

2013-10-11

372

Total synthesis of borrelidin.  

PubMed

The total synthesis of borrelidin has been achieved. The best feature of our synthetic route is macrocyclization at C11-C12 for the construction of an 18-membered ring after esterification between two segments. A detailed examination of the macrocyclization led us to the samarium(II) iodide-mediated intramolecular Reformatsky-type reaction as the most efficient synthetic approach. The two key segments were synthesized through regioselective methylation, directed hydrogenation, stereoselective Reformatsky-type reaction, and MgBr2.Et2O-mediated chelation-controlled allylation. PMID:17355148

Nagamitsu, Tohru; Takano, Daisuke; Marumoto, Kaori; Fukuda, Takeo; Furuya, Kentaro; Otoguro, Kazuhiko; Takeda, Kazuyoshi; Kuwajima, Isao; Harigaya, Yoshihiro; Omura, Satoshi

2007-04-13

373

Early failure of articular surface replacement XL total hip arthroplasty.  

PubMed

The ASR (articular surface replacement) XL (DePuy, Warsaw, Ind) metal-on-metal hip arthroplasty offers the advantage of stability and increased motion. However, an alarming number of early failures prompted the evaluation of patients treated with this system. A prospective study of patients who underwent arthroplasty with the ASR XL system was performed. Patients with 2-year follow-up or any revision were included. Failure rates, Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) scores, and radiographs were evaluated. Ninety-five patients (105 hips) were included. There were 16 revisions. Thirteen (12%) were aseptic acetabular failures. Eight were revised for aseptic loosening; 4, for metallosis; 1, for malposition; 2, for infection; and 1, for periprosthetic fracture. Mean time to revision was 1.6 years (0.18-3.4 years). The ASR XL with a revision rate of 12% is the second reported 1 piece metal-on-metal system with a significant failure rate at early follow-up. This particular class of implants has inherent design flaws that lead to early failure. PMID:21550764

Steele, Garen D; Fehring, Thomas K; Odum, Susan M; Dennos, Anne C; Nadaud, Matthew C

2011-09-01

374

Anisotropic Total Variation Filtering  

SciTech Connect

Total variation regularization and anisotropic filtering have been established as standard methods for image denoising because of their ability to detect and keep prominent edges in the data. Both methods, however, introduce artifacts: In the case of anisotropic filtering, the preservation of edges comes at the cost of the creation of additional structures out of noise; total variation regularization, on the other hand, suffers from the stair-casing effect, which leads to gradual contrast changes in homogeneous objects, especially near curved edges and corners. In order to circumvent these drawbacks, we propose to combine the two regularization techniques. To that end we replace the isotropic TV semi-norm by an anisotropic term that mirrors the directional structure of either the noisy original data or the smoothed image. We provide a detailed existence theory for our regularization method by using the concept of relaxation. The numerical examples concluding the paper show that the proposed introduction of an anisotropy to TV regularization indeed leads to improved denoising: the stair-casing effect is reduced while at the same time the creation of artifacts is suppressed.

Grasmair, Markus, E-mail: Markus.Grasmair@univie.ac.a [University of Vienna, Computational Science Center (Austria); Lenzen, Frank, E-mail: Frank.Lenzen@iwr.uni-heidelberg.d [University of Heidelberg, Heidelberg Collaboratory for Image Processing (Germany)

2010-12-15

375

Total systems design approach  

SciTech Connect

Dudley Products, Inc., an 85,327 ft{sup 2} facility, consists of 33,305 ft{sup 2} of offices and laboratories. It has 30 ft ceilings in the spacious lobby, and a 52,022 ft{sup 2} manufacturing facility with 22 ft ceilings. These facilities produce a total heated and cooled volumetric space of approximately 1.5 million cubic feet. This article describes a project to produce a guaranteed, performance-based Total System Design; to create a comfortable, energy-efficient green building, to apply ASHRAE Standards 55-1992, 62-1989 and 90.1-1989 for the efficient use of energy and to produce a healthy work environment; to construct a model Energy Efficient Facility for engineering schools and others in the HVAC-related industry; and to produce a project yielding immediate positive cash flow, making this project an excellent return on investment. Prior to construction, detailed computer modeling was used to substantiate the system/component method of compliance.

Boody, H.J.

1997-08-01

376

Total organic carbon analyzer  

NASA Technical Reports Server (NTRS)

The development and testing of a breadboard version of a highly sensitive total-organic-carbon (TOC) analyzer are reported. Attention is given to the system components including the CO2 sensor, oxidation reactor, acidification module, and the sample-inlet system. Research is reported for an experimental reagentless oxidation reactor, and good results are reported for linearity, sensitivity, and selectivity in the CO2 sensor. The TOC analyzer is developed with gravity-independent components and is designed for minimal additions of chemical reagents. The reagentless oxidation reactor is based on electrolysis and UV photolysis and is shown to be potentially useful. The stability of the breadboard instrument is shown to be good on a day-to-day basis, and the analyzer is capable of 5 sample analyses per day for a period of about 80 days. The instrument can provide accurate TOC and TIC measurements over a concentration range of 20 ppb to 50 ppm C.

Godec, Richard G.; Kosenka, Paul P.; Smith, Brian D.; Hutte, Richard S.; Webb, Johanna V.; Sauer, Richard L.

1991-01-01

377

Cervical Total Disc Arthroplasty  

PubMed Central

Symptomatic adjacent segment degeneration of the cervical spine remains problematic for patients and surgeons alike. Despite advances in surgical techniques and instrumentation, the solution remains elusive. Spurred by the success of total joint arthroplasty in hips and knees, surgeons and industry have turned to motion preservation devices in the cervical spine. By preserving motion at the diseased level, the hope is that adjacent segment degeneration can be prevented. Multiple cervical disc arthroplasty devices have come onto the market and completed Food and Drug Administration Investigational Device Exemption trials. Though some of the early results demonstrate equivalency of arthroplasty to fusion, compelling evidence of benefits in terms of symptomatic adjacent segment degeneration are lacking. In addition, non-industry-sponsored studies indicate that these devices are equivalent to fusion in terms of adjacent segment degeneration. Longer-term studies will eventually provide the definitive answer.

Basho, Rahul; Hood, Kenneth A.

2012-01-01

378

Total organic carbon analyzer  

NASA Astrophysics Data System (ADS)

The development and testing of a breadboard version of a highly sensitive total-organic-carbon (TOC) analyzer are reported. Attention is given to the system components including the CO2 sensor, oxidation reactor, acidification module, and the sample-inlet system. Research is reported for an experimental reagentless oxidation reactor, and good results are reported for linearity, sensitivity, and selectivity in the CO2 sensor. The TOC analyzer is developed with gravity-independent components and is designed for minimal additions of chemical reagents. The reagentless oxidation reactor is based on electrolysis and UV photolysis and is shown to be potentially useful. The stability of the breadboard instrument is shown to be good on a day-to-day basis, and the analyzer is capable of 5 sample analyses per day for a period of about 80 days. The instrument can provide accurate TOC and TIC measurements over a concentration range of 20 ppb to 50 ppm C.

Godec, Richard G.; Kosenka, Paul P.; Smith, Brian D.; Hutte, Richard S.; Webb, Johanna V.; Sauer, Richard L.

379

Total synthesis of depsilairdin.  

PubMed

The total synthesis of depsilairdin, a host-selective phytotoxin isolated from Leptosphaeria maculans (the causal agent of blackleg disease of oilseed Brassicas), has been achieved by N-terminal extension of a suitably protected derivative of the hitherto unknown amino acid (2S,3S,4R)-3,4-dihydroxy-3-methyl-proline (Dhmp) followed by esterification with lairdinol A. The latter esterification, complicated by the sterically hindered nature of the carboxyl group, was accomplished by a novel method involving reaction of the 1-hydroxybenzotriazole (HOBt) derived active ester with the bromomagnesium alkoxide of lairdinol A. Three depsilairdin analogues were also prepared by replacing the Dhmp residue with L-proline and cis- and trans-4-hydroxy-L-proline. Phytotoxicity assays showed that the analogues were nontoxic to both blackleg-susceptible (brown mustard) and -resistant (canola) plants, suggesting that the presence of the Dhmp residue in depsilairdin is important for its host-selective toxicity toward brown mustard. PMID:20670027

Ward, Dale E; Pardeshi, Sandip G

2010-08-01

380

Total disc replacement.  

PubMed

Total disc replacement (TDR) (partial disc replacement will not be described) has been used in the lumbar spine since the 1980s, and more recently in the cervical spine. Although the biomechanical concepts are the same and both are inserted through an anterior approach, lumbar TDR is conventionally indicated for chronic low back pain, whereas cervical TDR is used for soft discal hernia resulting in cervicobrachial neuralgia. The insertion technique must be rigorous, with precise centering in the disc space, taking account of vascular anatomy, which is more complex in the lumbar region, particularly proximally to L5-S1. All of the numerous studies, including prospective randomized comparative trials, have demonstrated non-inferiority to fusion, or even short-term superiority regarding speed of improvement. The main implant-related complication is bridging heterotopic ossification with resulting loss of range of motion and increased rates of adjacent segment degeneration, although with an incidence lower than after arthrodesis. A sufficiently long follow-up, which has not yet been reached, will be necessary to establish definitively an advantage for TDR, particularly in the cervical spine. PMID:24412045

Vital, J-M; Boissière, L

2014-02-01

381

Total Energy CMR Production  

SciTech Connect

The following outlines the optimized pulsed laser deposition (PLD) procedure used to prepare Nd{sub 0.67}Sr{sub 0.33}MnO{sub 3} (NSMO) temperature sensors at Towson University (Prof. Rajeswari Kolagani) for the LCLS XTOD Total Energy Monitor. The samples have a sharp metal/insulator transition at T {approx} 200 K and are optimized for operation at T {approx} 180 K, where their sensitivity is the highest. These samples are epitaxial multilayer structures of Si/YSZ/CeO/NSMO, where these abbreviations are defined in table 1. In this heterostructure, YSZ serves as a buffer layer to prevent deleterious chemical reactions, and also serves to de-oxygenate the amorphous SiO{sub 2} surface layer to generate a crystalline template for epitaxy. CeO and BTO serve as template layers to minimize the effects of thermal and lattice mismatch strains, respectively. More details on the buffer and template layer scheme are included in the attached manuscript accepted for publication in Sensor Letters (G. Yong et al., 2008).

Friedrich, S; Kolagani, R M

2008-08-11

382

The clinical and radiological outcomes of hip resurfacing versus total hip arthroplasty: a meta-analysis and systematic review  

PubMed Central

Background and purpose Hip resurfacing (HRS) procedures have gained increasing popularity for younger, higher-demand patients with degenerative hip pathologies. However, with concerns regarding revision rates and possible adverse metal hypersensitivity reactions with metal-on-metal articulations, some authors have questioned the hypothesized superiority of hip resurfacing over total hip arthroplasty (THA). In this meta-analysis, we compared the clinical and radiological outcomes and complication rates of these 2 procedures. Methods A systematic review was undertaken of all published (Medline, CINAHL, AMED, EMBASE) and unpublished or gray literature research databases up to January 2010. Clinical and radiological outcomes as well as complications of HRS were compared to those of THA using risk ratio, mean difference, and standardized mean difference statistics. Studies were critically appraised using the CASP appraisal tool. Results 46 studies were identified from 1,124 citations. These included 3,799 HRSs and 3,282 THAs. On meta-analysis, functional outcomes for subjects following HRS were better than or the same as for subjects with a THA, but there were statistically significantly greater incidences of heterotopic ossification, aseptic loosening, and revision surgery with HRS compared to THA. The evidence base showed a number of methodological inadequacies such as the limited use of power calculations and poor or absent blinding of both patients and assessors, possibly giving rise to assessor bias. Interpretation On the basis of the current evidence base, HRS may have better functional outcomes than THA, but the increased risks of heterotopic ossification, aseptic loosening, and revision surgery following HRS indicate that THA is superior in terms of implant survival.

2010-01-01

383

Determination of Total Petroleum Hydrocarbons (TPH) Using Total Carbon Analysis  

SciTech Connect

Several methods have been proposed to replace the Freon(TM)-extraction method to determine total petroleum hydrocarbon (TPH) content. For reasons of cost, sensitivity, precision, or simplicity, none of the replacement methods are feasible for analysis of radioactive samples at our facility. We have developed a method to measure total petroleum hydrocarbon content in aqueous sample matrixes using total organic carbon (total carbon) determination. The total carbon content (TC1) of the sample is measured using a total organic carbon analyzer. The sample is then contacted with a small volume of non-pokar solvent to extract the total petroleum hydrocarbons. The total carbon content of the resultant aqueous phase of the extracted sample (TC2) is measured. Total petroleum hydrocarbon content is calculated (TPH = TC1-TC2). The resultant data are consistent with results obtained using Freon(TM) extraction followed by infrared absorbance.

Ekechukwu, A.A.

2002-05-10

384

Recommended Amounts of Total dairy  

Cancer.gov

Recommended Amounts of Total dairy Table B15. Total dairy: Estimated percentage of persons below, at, or above recommendation1 Age (years) N Mean (SE) % with intake below recommendation (SE) % with intake meeting recommendation (SE) % with intake above

385

Recommended Amounts of Total seafood  

Cancer.gov

Recommended Amounts of Total seafood Table B12. Total seafood: Estimated percentage of persons below, at, or above recommendation1 Age (years) N Mean (SE) % with intake below recommendation (SE) % with intake meeting recommendation (SE) % with intake

386

Recommended Amounts of Total grains  

Cancer.gov

Recommended Amounts of Total grains Table B8. Total grains: Estimated percentage of persons below, at, or above recommendation1 Age (years) N Mean (SE) % with intake below recommendation (SE) % with intake meeting recommendation (SE) % with intake above

387

Recommended Amounts of Total fruits  

Cancer.gov

Recommended Amounts of Total fruits Table B1. Total fruits: Estimated percentage of persons below, at, or above recommendation1 Age (years) N Mean (SE) % with intake below recommendation (SE) % with intake meeting recommendation (SE) % with intake above

388

Risk of cancer following primary total hip replacement or primary resurfacing arthroplasty of the hip: a retrospective cohort study in Scotland  

PubMed Central

Background: Release and dispersion of particles arising from corrosion and wear of total hip arthroplasty (THA) components has raised concerns about a possible increased risk of cancer. Concerns have been heightened by a recent revival in the use of metal-on-metal (MoM) hip prostheses. Methods: From a linked database of hospital discharge, cancer registration, and mortality records, we selected a cohort of patients who underwent primary THA (1990–2009) or primary resurfacing arthroplasty (mainly 2000–2009) in Scotland, with follow-up to the end of 2010. Available operation codes did not enable us to distinguish MoM THAs. Indirectly standardised incidence ratios (SIRs) were calculated for selected cancers with standardisation for age, sex, deprivation, and calendar period. Results: The study cohort included 71?990 patients yielding 547?001 person-years at risk (PYAR) and 13?946 cancers diagnosed during follow-up. For the total period of observation combined, the risks of all cancers (SIR: 1.05; 95% CI: confidence interval 1.04–1.07), prostate cancer (SIR: 1.07; 95% CI: 1.01–1.14), and multiple myeloma (SIR: 1.22; 95% CI: 1.06–1.41) were increased. These modest increases in risk emerged in the context of effectively multiple tests of statistical significance, and may reflect inadequate adjustment for confounding factors. For 1317 patients undergoing primary resurfacing arthroplasty between 2000 and 2009 (PYAR=5698), the SIR for all cancers (n=39) was 1.23 (95% CI: 0.87–1.68). Conclusion: In the context of previous research, these results do not suggest a major cause for concern. However, the duration of follow-up of patients receiving recently introduced, new-generation MoM prostheses is too short to rule out a genuinely increased risk of cancer entirely.

Brewster, D H; Stockton, D L; Reekie, A; Ashcroft, G P; Howie, C R; Porter, D E; Black, R J

2013-01-01

389

Total quality index: a benchmarking tool for total quality management  

Microsoft Academic Search

The total quality index (TQI) proposed in this study is an information technology-supported benchmarking tool that helps managers assess a total quality management program by enabling the cost-effective measurement of key organizational processes. TQI utilizes the analytic hierarchy process and the Delphi technique to measure ideal and actual quality management along eight critical factors synthesized by Saraph et al. and

Madjid Tavana; Barbara Mohebbi; Dennis T. Kennedy

2003-01-01

390

Total Productive Maintenance and Its Link to Total Quality Management  

Microsoft Academic Search

This article addresses the question of why total quality management (TQM) and total productive maintenance (TPM) are valuable strategies for American businesses today. While each process is beneficial on its own, the synergy created by simultaneously doing both is incredibly powerful.

Robert S. Jostes; Marilyn M. Helms

1994-01-01

391

Prospective, Randomized Trial of Metal-on-Metal Artificial Lumbar Disc Replacement Initial Results for Treatment of Discogenic Pain  

Microsoft Academic Search

Study Design. This study presents data on 67 patients from 2 study sites involved in the multicenter, prospec- tive, randomized, controlled investigational device ex- emption study of FlexiCore artificial disc replacement ver- sus fusion with a 2-year follow-up. Objective. To compare the outcomes achieved with the FlexiCore disc replacement versus standard circum- ferential fusion for the treatment of discogenic pain

Rick C. Sasso; David M. Foulk; Michael Hahn

392

Metal-on-metal thin-film growth: Au/Ni(001) and Ni/Au(001)  

NASA Astrophysics Data System (ADS)

Growth modes and dynamics of vapor-deposited thin metal films on metal substrates are studied by means of molecular-dynamics simulations using embedded-atom interactions. Gold films deposited on a room-temperature Ni(001) substrate exhibit Stranski-Krastanov growth of Au(111) films, and growth of nickel films on Au(001) involves interspecies mixing and three-dimensional growth of strained films pseudomorphic to the substrate.

Luedtke, W. D.; Landman, Uzi

1991-09-01

393

Strain relief during metal-on-metal electrodeposition: a scanning tunneling microscopy study of copper growth on Pt(100)  

NASA Astrophysics Data System (ADS)

The galvanic deposition of copper on Pt(100)-(1 × 1) was studied in sulfate electrolyte by means of time-resolved in situ STM and voltammetry. Surprisingly, copper grows layer-by-layer in the absence of strongly adsorbing additives. This behavior persists beyond the deposition of two layers and is thus different from that found in analogous vacuum studies. After deposition of 5 to 10 layers, the deposit relaxes to the copper bulk structure. Due to the Cusbnd Pt misfit and the geometry of the Pt substrate, this results in a square-shaped moirépattern. For thick layers, the growth proceeds in the usual way, i.e. via three-dimensional clusters.

Bittner, A. M.; Wintterlin, J.; Ertl, G.

1997-04-01

394

Reentrant layer-by-layer growth during molecular-beam epitaxy of metal-on-metal substrates  

NASA Astrophysics Data System (ADS)

The discovery of a reentrant layer-by-layer growth during molecular-beam epitaxy of Pt on Pt(111) is reported. Explanations of the reentrant behavior based on previous field-ion-microscopy observations are proposed.

Kunkel, Ralf; Poelsema, Bene; Verheij, Laurens K.; Comsa, George

1990-08-01

395

Whole blood metal ion concentrations in correlation with activity level in three different metal-on-metal bearings.  

PubMed

Seventy consecutive osteoarthritis patients younger than 65 years undergoing a hip arthroplasty were included. Three different metal bearings were used (2 different resurfacing systems and one 28-mm metal bearing) and compared with a ceramic control group. Whole blood cobalt and chromium levels were analyzed preoperatively, at 3 months, 6 months, 1 year, and 2 years. Patients with steep cups (abduction >55°) were excluded. No significant differences in functional scores and activity level were found between either groups. Ion levels were significantly lower with one type of resurfacing. No correlation was found between ion and activity level. In conclusion, although the current second-generation metal bearings may show differences in ion release, more attention should be paid to the correlation between ion release and implant positioning. PMID:20171052

Pattyn, Christophe A; Lauwagie, Sofie N; Verdonk, René C

2011-01-01

396

Femoral neck resorption following hybrid metal-on-metal hip resurfacing arthroplasty: a radiological and biomechanical analysis  

Microsoft Academic Search

Introduction  With the resurgence of resurfacing hip arthroplasty complications such as femoral neck fracture and thinning have been identified.\\u000a We therefore conducted a radiological and biomechanical evaluation of factors affecting femoral neck resorption following\\u000a resurfacing hip arthroplasty (RHA).\\u000a \\u000a \\u000a \\u000a \\u000a Methods  We retrospectively reviewed 61 resurfacing hip arthroplasties in 53 patients with a minimum of a 2-year follow-up. Data regarding\\u000a age, gender, body mass

Jibu Joseph; Michael Mullen; Andrew McAuley; Anand Pillai

2010-01-01

397

A Novel Technique for the Removal of Well-Fixed Cementless, Large-Diameter Metal-on-Metal Acetabular Components  

Microsoft Academic Search

Removing well-fixed cementless acetabular components can be a challenge for every orthopedic surgeon involved in revision hip arthroplasty. Forceful removal of such components often leads to acetabular bone loss and compromises reimplantation of a new socket. Instruments like the Explant Acetabular Cup Removal System (Zimmer, Warsaw, Ind) are developed to avoid such issues. We report a novel technique, cementing a

Christophe Olyslaegers; Tom Wainwright; Robert G. Middleton

2008-01-01

398

Lubrication of metal-on-metal hip joints: the effect of protein content and load on film formation and wear.  

PubMed

Lubricant films were measured for a series of bovine serum and protein containing (albumin, globulin) saline solutions for CoCrMo femoral component sliding against a glass disc. Central film thickness was measured by optical interferometry as a function of time (constant mean speed: 0 and 10 mm/s) and variable mean speed (0-50 mm/s). The effect of load (5-20 N) on film thickness was also studied. The development of the wear scar on the CoCrMo surface was monitored by measuring the width of the contact zone during the film thickness tests. The results showed film thickness increased with time for both the static and sliding tests. Films formed in the static, loaded test were typically in the range of 3-40 nm. The globulin containing solutions formed the thickest films. In the sliding tests a wear scar rapidly formed on the implant component for the bovine serum and albumin fluids, negligible wear was observed for the globulin solutions. Film thickness increased with sliding time for all test solutions and was much greater than predicted by isoviscous EHL models. The film increase was found to correlate with increasing wear scar size and thus decreasing contact pressure. A new lubricating mechanism is proposed whereby during sliding the fluid undergoes bulk phase separation rheology, so that an elevated protein phase forms in the inlet zone. This protein phase is a high-viscosity biphasic matrix, which is periodically entrained into the contact forming a thick protective hydro-gel film. One of the main findings of this study is that film thickness was very sensitive to load; to a much greater extent than predicted by EHL models. Thus film formation in MoM hip joints is very susceptible to high contact pressures which might be due to implant misalignment and edge-loading. PMID:22301171

Myant, C; Underwood, R; Fan, J; Cann, P M

2012-02-01

399

Examination of failed ex vivo metal-on-metal metatarsophalangeal prosthesis and comparison with theoretically determined lubrication regimes  

Microsoft Academic Search

Replacement of the first metatarsophalangeal (MTP) joint is a relatively uncommon procedure compared with hip and knee arthroplasty. A cobalt chrome-on-cobalt chrome MTP prosthesis, which had a diamond-like carbon (DLC) coating applied to its articulating faces, was obtained for ex vivo analysis. By modelling the ball and socket implant as an equivalent ball-on-plane model and employing elastohydrodynamic theory, the predicted

T. J. Joyce

2007-01-01

400

Usual Intake of Total grains  

Cancer.gov

Usual Intake of Total grains Table A17. Total grains: Means, percentiles and standard errors of usual intake, 2007-2010 Age (Years) N1 oz equivalents3 Mean (SE)2 5% (SE) 10% (SE) 25% (SE) 50% (SE) 75% (SE) 90% (SE) 95% (SE) Males 1-3 774 4.1 (0.10) 2.2

401

Waiting for total hip arthroplasty  

Microsoft Academic Search

This study was conducted to determine the effect of waiting times for total hip arthroplasty in terms of loss in quality-adjusted life years and additional burden perceived. A second goal was to study the effect of waiting times and preoperative function scores on postoperative outcome scores. Data were collected prospectively from a cohort of 161 patients waiting for total hip

Marieke Ostendorf; Erik Buskens; Henk van Stel; Augustus Schrijvers; Louis Marting; Wouter Dhert; Abraham Verbout

2004-01-01

402

First total synthesis of (+)-indicanone.  

PubMed

The first total synthesis of the guaiane-type sesquiterpene, (+)-indicanone (1), isolated from the root of Wikstroemia indica, was accomplished based on the rhodium(I)-catalyzed Pauson-Khand-type reaction of the allenyne derivative, which was derived from (+)-limonene. This total synthesis unambiguously confirmed the complete structure of (+)-indicanone involving its absolute stereochemistry. PMID:22588646

Hayashi, Yujiro; Ogawa, Kumiko; Inagaki, Fuyuhiko; Mukai, Chisato

2012-06-28

403

Usual Intake of Total seafood  

Cancer.gov

Usual Intake of Total seafood Table A27. Total seafood: Means, percentiles and standard errors of usual intake, 2007-2010 Age (Years) N1 oz equivalents3 Mean (SE)2 5% (SE) 10% (SE) 25% (SE) 50% (SE) 75% (SE) 90% (SE) 95% (SE) Males 1-3 774 0.1 (0.02) 0.0

404

Usual Intake of Total fruit  

Cancer.gov

Usual Intake of Total fruit Table A1. Total fruit: Means, percentiles and standard errors of usual intake, 2007-2010 Age (Years) N1 cup equivalents3 Mean (SE)2 5% (SE) 10% (SE) 25% (SE) 50% (SE) 75% (SE) 90% (SE) 95% (SE) Males 1-3 774 1.5 (0.07) 0.6

405

Swivel Total-Temperature Probe  

NASA Technical Reports Server (NTRS)

Improved probe designed to be mounted at wingtip of airplane and used for measuring total temperature of air when airplane flies at high angles of attack. Four fins and swivel mount enable probe to align itself aerodynamically with local flow of air. Thus, stagnated-flow condition needed for accurate measurement of total temperature achieved.

Moes, Tim; Nichols, Doug; Vanderloop, Dirk; Rood, Rich

1996-01-01

406

Usual Intake of Total dairy  

Cancer.gov

Usual Intake of Total dairy Table A33. Total dairy: Means, percentiles and standard errors of usual intake, 2007-2010 Age (Years) N1 cup equivalents3 Mean (SE)2 5% (SE) 10% (SE) 25% (SE) 50% (SE) 75% (SE) 90% (SE) 95% (SE) Males 1-3 774 2.5 (0.07) 1.0

407

Total synthesis of batatoside L.  

PubMed

The total synthesis of batatoside L (1), a resin glycoside possessing cytotoxicity against laryngeal carcinoma cells, has been completed in a highly convergent manner. The most crucial step in this total synthesis was the efficient construction of the 18-membered macrolactone framework through the Corey-Nicolaou macrolactonization approach. PMID:20666429

Xie, Lin; Zhu, San-Yong; Shen, Xiao-Qiu; He, Li-Li; Yang, Jin-Song

2010-08-20

408

Labor participation rate, total (% of total population ages 15+)  

NSDL National Science Digital Library

Data set and map pertaining to total labor force participation rates for all countries. The World Bank specifies labor force participation as a World Development Indicator (WDI) -- the statistical benchmark that helps measure the progress of development.

Bank, World

409

Corrosion at the Head-Neck Taper as a Cause for Adverse Local Tissue Reactions After Total Hip Arthroplasty  

PubMed Central

Background: Corrosion at the modular head-neck junction of the femoral component in total hip arthroplasty has been identified as a potential concern, although symptomatic adverse local tissue reactions secondary to corrosion have rarely been described. Methods: We retrospectively reviewed the records of ten patients with a metal-on-polyethylene total hip prosthesis, from three different manufacturers, who underwent revision surgery for corrosion at the modular head-neck junction. Results: All patients presented with pain or swelling around the hip, and two patients presented with recurrent instability. Serum cobalt levels were elevated prior to the revision arthroplasty and were typically more elevated than were serum chromium levels. Surgical findings included large soft-tissue masses and surrounding tissue damage with visible corrosion at the femoral head-neck junction; the two patients who presented with instability had severe damage to the hip abductor musculature. Pathology specimens consistently demonstrated areas of tissue necrosis. The patients were treated with debridement and a femoral head and liner exchange, with use of a ceramic femoral head with a titanium sleeve in eight cases. The mean Harris hip score improved from 58.1 points preoperatively to 89.7 points at a mean of 13.0 months after the revision surgery (p = 0.01). Repeat serum cobalt levels, measured in six patients at a mean of 8.0 months following revision, decreased to a mean of 1.61 ng/mL, and chromium levels were similar to prerevision levels. One patient with moderate hip abductor muscle necrosis developed recurrent instability after revision and required a second revision arthroplasty. Conclusions: Adverse local tissue reactions can occur in patients with a metal-on-polyethylene bearing secondary to corrosion at the modular femoral head-neck taper, and their presentation is similar to the adverse local tissue reactions seen in patients with a metal-on-metal bearing. Elevated serum metal levels, particularly a differential elevation of serum cobalt levels with respect to chromium levels, can be helpful in establishing this diagnosis. Level of Evidence: Diagnostic Level III. See Instructions for Authors for a complete description of levels of evidence.

John Cooper, H.; Della Valle, Craig J.; Berger, Richard A.; Tetreault, Matthew; Paprosky, Wayne G.; Sporer, Scott M.; Jacobs, Joshua J.

2012-01-01

410

Controversies in total ankle replacement.  

PubMed

Although there exist general guidelines regarding which patients are "suitable" candidates for total ankle replacement, these guidelines tend to be very conservative, much like those of knee and hip replacement from decades ago. There are also no direct comparison studies of one total ankle replacement design with another. Because of the paucity of data, surgeons are left to surmise the opinion based on limited studies, as well as industry-sponsored data and advertising material. This article examines several key, controversial issues that apply to total ankle replacement. Recommendations and points for thought are provided. PMID:23164437

Bibbo, Christopher

2013-01-01

411

Total arsenic in rice milk.  

PubMed

Rice milk and its by-products were tested for total arsenic concentration. Total arsenic concentration was determined using graphite-furnace atomic absorption spectrometry. The arsenic concentrations ranged from 2.7 ± 0.3 to 17.9 ± 0.5 µg L(-1). Rice milk and its by-products are not clearly defined as food, water or milk substitute. The US Environmental Protection Agency (EPA), the European Union (EU) and the World Health Organization (WHO) have set a level of 10 µg L(-1) for total arsenic concentrations in drinking water. The EU and the US regulatory agencies do not provide any guidelines on total arsenic concentrations in foods. This study provides us with a starting point to address this issue in the State of Mississippi, USA. PMID:24779982

Shannon, Ron; Rodriguez, Jose M

2014-03-01

412

Economic Evaluation of Total Energy.  

National Technical Information Service (NTIS)

Total energy systems are onsite power generation systems with heat recovery. By generating electricity on the premises, it is possible to recover normally wasted heat and use it to provide space heating, cooling, and domestic water heating. The objective ...

D. Glenn J. Oplinger J. Orlando

1973-01-01

413

Noise from total hip replacements  

PubMed Central

Objectives Our study aimed to examine not only the incidence but also the impact of noise from two types of total hip replacement articulations: ceramic-on-ceramic and ceramic-on-polyethylene. Methods We performed a case-controlled study comparing subjective and objective questionnaire scores of patients receiving a ceramic-on-ceramic or a ceramic-on-polyethylene total hip replacement by a single surgeon. Results There was a threefold higher incidence of noise from patients in the ceramic-on-ceramic group compared with the control group. The impact of this noise was significant for patients both subjectively and objectively. Conclusions This study reports a high patient impact of noise from ceramic-on-ceramic total hip replacements. This has led to a change in practice by the principal author. Cite this article: Bone Joint Res 2014;3:183–6.

Wyatt, M. C.; Jesani, S.; Frampton, C.; Devane, P.; Horne, J. G.

2014-01-01

414

Totally Ossified Metaplastic Spinal Meningioma  

PubMed Central

A 61-year-old woman with a very rare case of totally ossified large thoracic spinal metaplastic meningioma, showing progressing myelopathy is presented. Computed tomographic images showed a large totally ossfied intradural round mass occupying the spinal canal on T9-10 level. Magnetic resonance imaging revealed a large T9-10 intradural extramedullary mass that was hypointense to spinal cord on T1- and T2-weighted sequences, partial enhancement was apparent after Gadolinium administration. The spinal cord was severely compressed and displaced toward the right at the level of T9-10. Surgical removal of the tumor was successfully accomplished via the posterior midline approach and the histological diagnosis verified an ossified metaplastic meningioma. The clinical neurological symptoms of patient were improved postoperatively. In this article we discuss the surgical and pathological aspects of rare case of spinal totally ossified metaplastic meningioma.

Hida, Kazutoshi; Yamauchi, Tomohiro; Houkin, Kiyohiro

2013-01-01

415

Global trends in total ozone  

NASA Technical Reports Server (NTRS)

Satellite ozone data from the Total Ozone Mapping Spectrometer from 1979 through 1986 show that recent decreases of total ozone have not been confined to the Antarctic spring season (the Antarctic ozone hole), but are global in extent. The losses are about twice the estimated uncertainty in the satellite data. The decreases are largest in middle and high latitudes and occur in all seasons of the year. The decreases for this 8-year period are comparable in magnitude to the increases observed during the 1960s. Southern Hemisphere values from 1986 are generally greater than those from 1985.

Bowman, Kenneth P.

1988-01-01

416

Total synthesis of (+)-lysergic acid.  

PubMed

A stereocontrolled total synthesis of (+)-lysergic acid (1) is achieved using three metal-catalyzed methodologies for the construction of three key rings. Highlights of the synthesis include Pd-catalyzed indole synthesis to form the B ring, a RCM reaction to form the D ring, and an intramolecular Heck reaction to form the C ring. PMID:21866948

Liu, Qiang; Jia, Yanxing

2011-09-16

417

Total synthesis of spirobacillene A.  

PubMed

The first total synthesis of spirobacillene A, an indole alkaloid isolated from Lysinibacillus fusiformis, is reported. A Lewis acid mediated spirocyclization of an anisole derivative onto a tethered ynone was used as a key step, drawing inspiration from a potential biosynthesis of the natural product. PMID:23786419

Unsworth, William P; Cuthbertson, James D; Taylor, Richard J K

2013-07-01

418

Energy Planning: A Total Concept.  

ERIC Educational Resources Information Center

Harvard's energy conservation plan is presented in detail with the hope that it will suggest practical, cost-effective energy-saving ideas to other institutions, and to dispel frequently-expressed fears concerning the feasibility and acceptance problems of this type of program. The total energy plan incorporates numerous specific elements that…

Hall, Stephen S. J.

1975-01-01

419

Total synthesis of sporolide B.  

PubMed

An ocean of discovery: The first total synthesis of the highly oxygenated, marine-derived, natural product sporolide B has been achieved through a convergent strategy. The key steps involve a ruthenium-catalyzed [2+2+2] cycloaddition to assemble the indene structural motif and a thermally induced Diels-Alder-type reaction to forge the macrocycle (see scheme). PMID:19241430

Nicolaou, K C; Tang, Yefeng; Wang, Jianhua

2009-01-01

420

Total Antioxidant Capacity of Fruits  

Microsoft Academic Search

The total antioxidant activity of 12 fruits and 5 commercial fruit juices was measured in this study using automated oxygen radical absorbance capacity (ORAC) assay. On the basis of the wet weight of the fruits (edible portion), strawberry had the highest ORAC activity (micromoles of Trolox equivalents per gram) followed by plum, orange, red grape, kiwi fruit, pink grapefruit, white

Hong Wang; Guohua Cao; Ronald L. Prior

1996-01-01

421

Total Synthesis of (+)-Scholarisine A  

PubMed Central

An effective total synthesis and assignment of the absolute configuration of the architecturally challenging (+)-scholarisine A has been achieved via a 20-step sequence. Highlights include a reductive cyclization, involving a nitrile and an epoxide; a modified Fischer indole protocol; a late stage oxidative-lactonization; and an intramolecular cyclization leading to the indolenine ring system of (+)-scholarisine A.

Adams, Gregory L.; Carroll, Patrick J.; Smith, Amos B.

2012-01-01

422

Total Quality Management in Education.  

ERIC Educational Resources Information Center

Ways to apply the concepts and processes of Total Quality Management (TQM) to education are discussed in this document. Following the introduction and the preface, chapter 1 provides a historical overview and describes the four cornerstones of TQM--an understanding of systems, psychology, knowledge, and statistics. Chapter 2 describes some of the…

Johnson, James H.

1993-01-01

423

Total Synthesis of (-)-Nakadomarin A  

PubMed Central

A concise diastereoselective total synthesis of (–)-nakadomarin A has been completed in 21 steps from D-pyroglutamic acid. Key steps include an enecarbamate Michael addition/furan-N-acyliminium ion cascade cyclization to provide the tetracyclic core, and ring-closing alkyne and alkene metatheses to construct the 15- and 8-membered azacycles, respectively.

Nilson, Mark G.; Funk, Raymond L.

2011-01-01

424

Total Synthesis of (+)-Lepadin F  

PubMed Central

An enantioselective total synthesis of (+)-lepadin F is described. The synthetic sequence features an intermolecular aza-[3 + 3] annulation, homologation of a vinylogous amide via Eschenmoser’s episulfide contraction, and a highly stereoselective hydrogenation essential for achieving the 1,3-anti relative stereochemistry at C2 and C8a.

Li, Gang; Hsung, Richard P.; Slafer, Brian W.; Sagamanova, Irina K.

2009-01-01

425

Complications of total parenteral nutrition  

Microsoft Academic Search

Continued technological improvements in the quality of nutritional formulations and techniques for parenteral administration have resulted in a major improvement in patient care. The ability to provide all necessary nutrients by intravenous infusion, so-called total parenteral nutrition (TPN), has sustained life and growth in patients who otherwise would have died. Most adult patients who derive benefit from this procedure are

James P Knochel

1985-01-01

426

The Total Cost of Ownership.  

ERIC Educational Resources Information Center

Examines what Total Cost of Ownership is regarding the purchase of technological resources for schools and the major expenses that are likely to occur after technological hardware and software have been installed. A list of best practices that can reduce costs approximately 15 percent and a checklist for technology budgeting are provided. (GR)

Day, C. William

2000-01-01

427

Total Library Computerization for Windows.  

ERIC Educational Resources Information Center

Presents a general review of features of version 2.1 of Total Library Computerization (TLC) for Windows from On Point, Inc. Includes information about pricing, hardware and operating systems, modules/functions available, user interface, security, on-line catalog functions, circulation, cataloging, and documentation and online help. A table…

Combs, Joseph, Jr.

1999-01-01

428

The total synthesis of neoamphimedine.  

PubMed

Neoamphimedine, a pyridoacridine alkaloid from Xestospongia sp., is a potent antitumor agent both in vitro and in vivo. Neoamphimedine can efficiently induce topoisomerase II mediated catenation of plasmid DNA in vitro and is the only member of more than one hundred pyridoacridines thus far to have this mechanism of action. Herein we report the first total synthesis of neoamphimedine. PMID:17900144

LaBarbera, Daniel V; Bugni, Tim S; Ireland, Chris M

2007-10-26

429

The Total Synthesis of Neoamphimedine  

PubMed Central

Neoamphimedine, a Pyridoacridine alkaloid from Xestospongia sp., is a potent antitumor agent both in vitro and in vivo. Neoamphimedine can efficiently induce topoisomerase II mediated catenation of plasmid DNA in vitro, and is the only member of more than one hundred pyridoacridines thus far to have this mechanism of action. Herein we report the first total synthesis of Neoamphimedine.

LaBarbera, Daniel V.; Bugni, Tim S.; Ireland, Chris M.

2008-01-01

430

Total synthesis of (+)-kopsihainanine A.  

PubMed

Total synthesis of (+)-kopsihainanine A was accomplished on the basis of (i) Stoltz's enantioselective decarboxylative asymmetric allylation and (ii) the proposed biogenetic pathway from the related alkaloid, kopsihainanine B. In addition, HPLC analysis of the synthetic (+)-kopsihainanine A confirmed its ee to be 99% with [?] = 25.35. PMID:24756124

Mizutani, Masaya; Yasuda, Shigeo; Mukai, Chisato

2014-06-01

431

The first Polish total laryngectomies.  

PubMed

The total removal of the larynx (total laryngectomy), performed in 1872 by the well-known Viennese surgeon Christian A. Theodor Billroth (1829-1894), was an epoch-making event in the history of surgery and laryngology. This paper presents the first surgeons who performed this operation. The first Pole who performed a total laryngectomy (1877) was Julian Kosi?ski (1833-1914), head of the Surgical Clinic of Imperial University Warsaw. It was the 14(th) operation of this kind in the world. Several laryngectomies were carried out by Franciszek Ksawery Jawdy?ski (1851-1896), called the father of Polish head and neck surgery, who was the first Pole to excise a malignant neck cancer together with the lymph nodes. The next total laryngectomies were performed by the following Polish surgeons: Jan Mikulicz-Radecki (1850-1905), W?adys?aw H.S. Krajewski (1855-1907), Alfred Obali?ski (1843-1898). According to Jan S?dziak, by 1897 Poland with 16 laryngectomies (per 188 carried out) had occupied the fourth position in the world. The failures of the first laryngectomies were due to such factors as the ignorance of shock pathophysiology, the inability to ensure the patency of the airways during and after the operation, which would result in lung and mediastinum infections, massive haemorrhages and so on. But the primary cause was the lack of constructive collaboration between the laryngologists and the surgeons. PMID:24592132

Kierzek, Andrzej; Paprocka-Borowicz, Ma?gorzata; Pozowski, Andrzej; Kuciel-Lewandowska, Jadwiga

2013-01-01

432

Enantioselective total synthesis of hyperforin.  

PubMed

A modular, 18-step total synthesis of hyperforin is described. The natural product was quickly accessed using latent symmetry elements, whereby a group-selective, Lewis acid-catalyzed epoxide-opening cascade cyclization was used to furnish the bicyclo[3.3.1]nonane core and set two key quaternary stereocenters. PMID:23270309

Sparling, Brian A; Moebius, David C; Shair, Matthew D

2013-01-16

433

Totally Magic Injections of Graphs  

Microsoft Academic Search

For a simple graph G consider an injection µ: V ( E ! N. If for every vertex x 2 V we have µ(x )+ P yx µ(xy )= h, and for every edge xy 2 E we have µ(x )+ µ(xy )+ µ(y )= k, for some constants h and k, then µ is a totally magic injection (TMI)

John P. McSorley

434

Bilateral transaxillary endoscopic total thyroidectomy  

Microsoft Academic Search

Background\\/PurposeMinimal-access thyroid surgery using various techniques is well described. The present study reviews our initial experience with total thyroidectomy using a robotic-assisted bilateral transaxillary endoscopic approach (R-BAEA) and a non–robotic-assisted bilateral transaxillary endoscopic approach (BAEA) to assess it's safety and feasibility.

Go Miyano; Thom E. Lobe; Simon K. Wright

2008-01-01

435

Total Phenolics and Total Flavonoids in Selected Indian Medicinal Plants  

PubMed Central

Plant phenolics and flavonoids have a powerful biological activity, which outlines the necessity of their determination. The phenolics and flavonoids content of 20 medicinal plants were determined in the present investigation. The phenolic content was determined by using Folin-Ciocalteu assay. The total flavonoids were measured spectrophotometrically by using the aluminium chloride colorimetric assay. The results showed that the family Mimosaceae is the richest source of phenolics, (Acacia nilotica: 80.63 mg gallic acid equivalents, Acacia catechu 78.12 mg gallic acid equivalents, Albizia lebbeck 66.23 mg gallic acid equivalents). The highest total flavonoid content was revealed in Senna tora which belongs to the family Caesalpiniaceae. The present study also shows the ratio of flavonoids to the phenolics in each sample for their specificity.

Sulaiman, C. T.; Balachandran, Indira

2012-01-01

436

Solar total energy project Shenandoah  

NASA Astrophysics Data System (ADS)

A description of the final design for the Solar Total Energy System to be installed at the Shenandoah, Georgia, site of utilization by the Bleyle knitwear plant, is presented. The system is a fully cascaded total energy system design featuring high temperature paraboloidal dish solar collectors with a 235 concentration ratio, a steam Rankine cycle power conversion system capable of supplying 100 to 400 kW(e) output with an intermediate process steam take-off point, and a back pressure condenser for heating and cooling. The design also includes an integrated control system employing the supervisory control concept to allow maximum experimental flexibility. The system design criteria and requirements are presented including the performance criteria and operating requirements, environmental conditions of operation; interface requirements with the Bleyle plant and the Georgia Power Company lines; maintenance, reliability, and testing requirements; health and safety requirements; and other applicable ordinances and codes.

1980-01-01

437

Total and subtotal abdominal hysterectomy.  

PubMed

Hysterectomy is one of the most frequently performed operations in the world, accounting for 500,000-600,000 procedures annually in the USA; the abdominal route for hysterectomy is the preferred route in 60-80% of these operations. Although the number of total abdominal hysterectomies performed annually has decreased, the number of subtotal abdominal hysterectomies increased by >400%. The major indications for abdominal hysterectomy include abnormal uterine bleeding, myomata uteri, adenomyosis, endometriosis, neoplasia, and chronic salpingitis. The basis for selection for subtotal versus total hysterectomy has little in the way of factual data to support it and may actually present some significant disadvantages, such as continued menstruation and cervical prolapse. The detailed technique for performing intrafascial abdominal hysterectomy relies heavily on precise knowledge of pelvic anatomy and compulsive detail to tissue handling. The consistent and correct usage of prophylactic antimicrobials, measures to prevent thromboemboli, and procedures to avoid urinary retention are key to the overall success of the surgery. PMID:15985251

Baggish, Michael S

2005-06-01

438

Total Synthesis of Apoptolidin A  

PubMed Central

A highly convergent, enantioselective total synthesis of the potent antitumor agent apoptolidin A, has been completed. The key transformations include highly selective glycosylations to attach the C27 disaccharide and the C9 6?-deoxy-l-glucose, a cross metathesis to incorporate the C1-C10 trienoate unit, and a Yamaguchi macrolactonization to complete the macrocycle. Twelve stereocenters in the polypropionate segments and sugar units were established through diastereoselective chlorotitanium enolate aldol reactions.

Crimmins, Michael T.; Christie, Hamish S.; Long, Alan; Chaudhary, Kleem

2009-01-01

439

Stiffness in total knee arthroplasty  

Microsoft Academic Search

Stiffness is a relatively uncommon complication after total knee arthroplasty. It has been defined as a painful limitation\\u000a in the range of movement (ROM). Its pathogenesis is still unclear even if some risk factors have been identified. Patient-related\\u000a conditions may be difficult to treat. Preoperative ROM is the most important risk factor, but an association with diabetes,\\u000a reflex sympathetic dystrophy,

Alfredo Schiavone Panni; Simone Cerciello; Michele Vasso; Mario Tartarone

2009-01-01

440

Total Synthesis of Theopederin D  

PubMed Central

The total synthesis of the potent cytotoxin theopederin D has been achieved through the use of an oxidative carbon–carbon bond cleavage reaction to form an acyliminium ion in the presence of acid labile acetal groups Other key transformations include an acid mediated functionalization of a tetrahydrofuranyl alcohol in the presence of a tetrahydropyranyl alcohol, a syn-selective glycal epoxide opening, and a catalytic asymmetric aldehyde-acid chloride condensation.

Green, Michael E.; Rech, Jason C.

2012-01-01

441

Enantioselective Total Synthesis of Aplyviolene  

PubMed Central

The enantioselective total synthesis of the rearranged spongian diterpene aplyviolene has been completed in 14 steps from the known hydroazulenone 8. The key junction of the hydrocarbon and oxygenated fragments to form the critical C8 quaternary carbon stereocenter and set the stage for elaborating the delicate bicyclic lactone functionality was accomplished in high yield and exquisite stereoselectivity by Michael addition of an enantioenriched hydroazulenone enolate to an enantiopure ?-bromocyclopentenone.

Overman, Larry E.; Schnermann, Martin J.

2011-01-01

442

Total Synthesis of Aplyronine C  

PubMed Central

A highly stereocontrolled total synthesis of the cytotoxic marine macrolide aplyronine C is described. The route exploits aldol methodology to install the requisite stereochemistry and features a crucial boron-mediated aldol coupling of an N-vinylformamide-bearing methyl ketone with a macrocyclic aldehyde to introduce the full side chain. The synthesis of two novel C21–C34 side chain analogs is also reported.

2013-01-01

443

Total Synthesis of Phomactin A.†  

PubMed Central

A total synthesis of (±)-phomactin A is described to highlight the final completion of a complex natural product target that had commenced with an intramolecular oxa-[3 + 3] annulation strategy in the construction of the ABD-tricycle. These efforts reveal structural intricacies of this ABD-tricycle with an illustrative example being the conformational analysis that was ultimately critical for the C5a-homolgation.

Tang, Yu; Cole, Kevin P.; Buchanan, Grant S.; Li, Gang; Hsung, Richard P.

2009-01-01

444

A totally transparent alignment sensor  

SciTech Connect

We describe the development of a totally transparent CCD based optical beam position sensing device that can measure transverse displacements with an accuracy of a few microns at a distance of many meters. The device includes on sensor DSP processing of the signal spectra with background subtraction and calibration to produce a compressed beam position, sensor address/status readout in token serial strings of sensors. The position monitoring system for the CMS Endcap Muon detector is presented as an intended application.

Jorge Moromisato et al.

1998-11-01

445

Total intravenous feeding of calves.  

PubMed

Total intravenous feeding was accomplished for 5 clinically normal calves and for 1 calf with atresia coli. During the trials, which lasted 8 to 14 days (mean of 12 days), calves were not permitted to ingest any food or water. Body weight and state of hydration remained essentially constant. Plasma protein content decreased, but there were only minor changes in other physiologic measures. Calves were clinically normal at the conclusion of the trials. PMID:407200

Hoffsis, G F; Gingerich, D A; Sherman, D M; Bruner, R R

1977-07-01

446

The essence of total synthesis  

PubMed Central

For the past century, the total synthesis of natural products has served as the flagship of chemical synthesis and the principal driving force for discovering new chemical reactivity, evaluating physical organic theories, testing the power of existing synthetic methods, and enabling biology and medicine. This perspective article seeks to examine this time-honored and highly demanding art, distilling its essence in an effort to ascertain its power and future potential.

Nicolaou, K. C.; Snyder, Scott A.

2004-01-01

447

Enantioselective total synthesis of borrelidin.  

PubMed

The first total synthesis of the natural product borrelidin is described. The propionate fragment of the molecule was concisely synthesized through catalytic enantioselective reductive aldol reactions, a catalytic Negishi coupling, and a catalytic directed hydrogenation. The propionate segment was then fused to the vinyl iodide fragment through a catalytic Sonogashira coupling. Subsequent catalytic hydrostannylation and catalytic cyanation allowed access to the target structure. PMID:12568588

Duffey, Matthew O; LeTiran, Arnaud; Morken, James P

2003-02-12

448

Epithelial phenotype in total sclerocornea  

PubMed Central

Purpose To understand whether the epithelial phenotype in total sclerocornea is corneal or conjunctival in origin. Methods Four cases of total sclerocornea (male:female = 1:3; mean age = 5.4±4.3; 1–11 years old) who received penetrating keratoplasty (PKP) at our hospital between 2008 and 2011 were included. Corneal buttons obtained during PKP were used for transmission electron microscopy (TEM) as well as immunoconfocal microscopy for cytokeratins 3, 12, and 13, goblet cell mucin MUC5AC, connexin 43, stem cell markers p63 and ABCG2, laminin-5, and fibronectin. Results After a mean follow-up period of 38.8±14.0 (12–54) months, the grafts remained clear in half of the patients. TEM examination revealed a markedly attenuated Bowman’s layer in the scleralized corneas, with irregular and variably thinned collagen lamellar layers, and disorganization and random distribution of collagen fibrils, which were much larger in diameter compared with a normal cornea.