Hip arthroplasty with the articular surface replacement (ASR) system: survivorship analysis and functional outcomes

Background

The articular surface replacement (ASR) hip resurfacing system, now withdrawn, has the highest all-cause revision rate (24.2 % at 7 years) compared with other resurfacing brands. We present our experience with the ASR articulation and the implant recall process.

Methods

We reviewed the medical records and examined all 55 patients (57 hips) who had THA by the senior author between March 2005 and November 2008. We recorded the Oxford Hip scores, metal ion levels, need for revision, the indication for revision, and the intra-operative findings. Radiographs were performed at the time of recall to detect component failure.

Results

Survival at 5 years with revision for any reason as the endpoint was 85.1 % for all patients. At the time of recall, 10 (17.5 %) of fifty-seven THAs were already revised. Four (40 %) of the ten revisions were performed within 1 month of the operation due to a periprosthetic fracture. Three other revisions were due to avascular necrosis at a mean time of 3.6 years. One patient was revised due to infection. The two remaining revisions were due to ongoing groin pain, in one of whom the cup was found to be loose.

Conclusions

Our data indicate an overall high revision rate, comparable with recently published studies. Even though most of our revisions were attributed to causes that are not specific to the metal-on-metal articulation, we do expect to find more cases of failures in the future. Therefore, continued close clinical surveillance and laboratory monitoring of these patients is warranted.     

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

Background

Failure of metal-on-metal (MOM) total hip arthroplasty (THA) bearings is often accompanied by an aggressive local reaction associated with destruction of bone, muscle, and other soft tissues around the hip. Little is known about whether patient-reported physical and mental function following revision THA in MOM patients is compromised by this soft tissue damage, and whether revision of MOM THA is comparable with revision of hard-on-soft bearings such as metal-on-polyethylene (MOP).

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

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.Metal-on-metal (MoM) total hip replacements have been used since the 1960s. Failure in early designs was attributed to mechanical loosening caused by poor bearing tolerances producing high friction (Amstutz and Grigoris 1996, Kothari et al. 1996). Improved manufacturing and engineering techniques enabled the development of a new generation of MoM hip replacements. In the 1990s, the Birmingham Hip Resurfacing (BHR) was developed, and good early to medium-term results have been published (Daniel et al. 2004, Treacy et al. 2005, Heilpern et al. 2008). Similar implants, both resurfacings and large MoM bearings, coupled with standard femoral stems were subsequently developed and marketed by other manufacturers.The development of magnetic resonance imaging (MRI) metal artifact reduction (MAR) sequences has enabled good visualization of the periprosthetic tissues (Toms et al. 2008), and been reported to be a clinically useful part of the assessment of painful MoM hip replacements (Hart et al. 2009). A number of authors have described the appearance of collections of fluid and inflammatory masses around painful MoM hip arthroplasties (Boardman et al. 2006, Pandit et al. 2008, Toms et al. 2008). These have been grouped under a variety of headings such as “aseptic lymphocyte-dominated vasculitis-associated lesions” (Willert et al. 2005), “pseudotumors” (Pandit et al. 2008), or “adverse reactions to metal debris (ARMD)” (Langton et al. 2010). Although these lesions have been previously described in patients investigated for pain, there have been no studies on the overall incidence of these lesions in an unselected series of patients, including those with no, or few, symptoms. It is not known whether these lesions may occur in the absence of symptoms.At our institution, we have a policy of offering routine MAR MRI imaging to patients who have undergone MoM total hip replacement or resurfacing. We determined the early clinical outcome, revision rate, and incidence of ARMD using MAR MRI screening in a consecutive series of patients with an ASR THR or resurfacing (ASR; DePuy, Leeds, UK).     

Hip resurfacing and osteonecrosis: results from an independent hip resurfacing register

Introduction

Single surgeon studies from specialized centers have suggested that metal-on-metal hip resurfacing in patients with osteonecrosis of hip joint provides good implant survival and function.

Method

We tested the hypothesis that multicenter results of hip resurfacing, in terms of function and survival, are similar between patients with osteoarthritis and osteonecrosis.

Patients

192 patients (202 hips) underwent metal-on-metal hip resurfacing at different centers around the world. We compared the revision risks in 95 patients (101 hips) with osteonecrosis and 97 patients (101 hips) with osteoarthritis.

Results

The mean age at operation was 42 and 43 years and the preoperative and postoperative Harris hip scores were 62 and 96 and 58 and 95 for osteonecrosis and osteoarthritis groups. Survival with revision for any reason as the end point at last follow-up was 97.7% for osteonecrosis and 95.0% for osteoarthritis.

Conclusion

We conclude that hip resurfacing can be offered to patients with osteonecrosis.     

Imaging Metal-on-Metal Hip Replacements: the Norwich Experience

Background

Adverse reaction to metal debris is a relatively recently described and often a silent complication of metal-on-metal (MOM) total hip replacements (THR). The Norfolk & Norwich University Hospital has been performing metal artefact reduction (MARS) MRI for 8 years in a variety of different types of MOM THR.

Questions/purposes

The aims of this review are to describe the experience of using MARS MRI in Norwich and to compare our experience with that published by other groups.

Methods

A MEDLINE keyword search was performed for studies including MRI in MOM THR. Relevant publications were reviewed and compared with published data from the Norfolk & Norwich University Hospital. The similarities and differences between these data were compared and possible explanations for these discussed.

Results

MARS MRI appears to be the most useful tool for diagnosing, staging and monitoring adverse reactions to metal debris (ARMD). There appears to be no clinically useful association between clinical and serological markers of disease and the severity of MR findings. Although severe early ARMD is associated with significant morbidity, mild disease is often stable for years. If patients with normal initial MR examinations develop ARMD, this usually occurs 7 years. A 1-year interval between MRI examinations is reasonable in asymptomatic patients.

Conclusions

There is a general international consensus that ARMD is prevalent in symptomatic and asymptomatic patients with MOM THR and that while appearances vary with the type of prosthesis, there are characteristic features that make MARS MRI essential for diagnosis, staging and surveillance of the disease.     

Blood metal ion concentrations in metal-on-metal total hip arthroplasty

Introduction

The hip placement with a metal-on-metal (MOM) bearing has been used for both surface replacement and total hip arthroplasty (THA). Use of MOM bearing for hip replacement reduces the wear compared to conventional bearings.

Methods

We prospectively assessed 30 patients who underwent unilateral MOM THA. A control group of 30 patients who underwent metal-on-polyethylene THA using the implants as the other group, except for bearing, were accessed. Blood samples were collected preoperatively and at 3- , 6- , 9- , 12- , 15- , 18- , and 24-month intervals. Changes in mean blood metal ion concentration were compared between the MOM and metal-on-polyethylene groups.

Results

A statistically significant positive correlation was observed between blood cobalt and chromium concentrations in all of the patients. The mean blood ion concentrations of the MOM were significantly higher than those of the metal-on-polyethylene. A statistically significant negative correlation was found between maximum blood cobalt concentration and cup version angle. The maximum blood chromium concentrations in the patients who had larger cup version angles were more likely to decrease.

Conclusions

We considered that cup version angle is one of the factors that have the greatest effect on blood metal ion concentration, and the target cup version angle that did not induce an increase in blood metal ion concentrations was approximately 20°.

     

Acetabular Cup Design Influences Deformational Response in Total Hip Arthroplasty

Background

Press-fit acetabular components are susceptible to deformation in an underreamed socket, with excessive deformation of metal-on-metal (MOM) components potentially leading to increased torsional friction and micromotion. Specifically, however, it remains unclear how cup diameter, design, and time from implantation affect shell deformation.

Questions/purposes

We asked whether (1) changes in component geometry and material altered maximum shell deformation and (2) time-dependent deformational relaxation processes occurred.

Methods

Diametral deformation was quantified after press-fit implantation of metal shells into a previously validated polyurethane model. Experimental groups (n = 6–8) consisted of 48-, 54-, 60-, and 66-mm MOM cups of 6-mm wall thickness, 58-mm cups of 10-mm wall thickness, and CoCrMo and Ti6Al4V 58-mm modular cups.

Results

Greater cup diameter, thinner wall construction, and Ti6Al4V modular designs generated conditions for maximum shell deformation ranging from 0.047 to 0.267 mm. Relaxation (18%–32%) was observed 120 hours postimplantation in thin-walled and modular designs.

Conclusions

Our findings demonstrate a reduction of shell deformation over time and suggest, under physiologic loading, early component deformation varies with design.

Clinical Relevance

Component deformation should be a design consideration regardless of bearing surface. Designs neglecting to adequately address deformational changes in vivo could be susceptible to diminished cup survival, increased wear, and premature revision.     

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

Introduction

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

Methods

Between 1997 and 1999, 121 total hip replacements in 114 patients were performed at a single centre by two senior surgeons, using the same prosthesis with a MOM hard-bearing surface of 28 mm diameter. At the mean follow-up of 5 years and 6 months (range 5–7 years), nine patients had died and three were lost to follow-up. We reviewed 107 hips (101 patients). The radiographs and case notes of deceased patients were examined. Follow-up was thus 117 out of 121 hips (96%). Results were evaluated clinically with the Merle d’Aubigne classification, and radiographically with analysis of implant migration and radiolucent lines in the Delee and Charnley areas. The survival rate was calculated.

Results

Six patients (5.6%) had revision surgery for aseptic loosening of the cup: one 2 years after the primary operation, two after 4 years, two after 5 years and one after 6 years. The clinical results according to Postel-Merle d’Aubigne gave 85 excellent results (80%), 10 good results (9.4%) and 6 bad results (5.6%). At the latest follow-up, there were no signs of migration, osteolysis or radiolucent lines involving the femoral component. In the acetabular component, there were five cases of radiolucent lines smaller than 1 mm, which were not progressive. In 24 cases, the radiolucent lines progressed over time and there was a probable failure in 18 cases. The survival rate at 5 years is 94.8% taking revision for any cause as the endpoint and 86.9% taking revision or impending failure (as ascertained by radiographic review) of the cup as the endpoint. Numbers of revisions and radiographic failures were significantly higher with the smaller cups (<48 mm diameter) than the larger (p < 0.05).

Conclusions

This series reports a higher rate of failure with a cemented polyethylene cup with a MOM insert than that reported in the scientific literature for metal-on-polyethylene-bearing surface or MOM uncemented cups. Other similar studies found in the literature are discussed. The authors do not recommend use of this cemented polyethylene-Metasul^® acetabular component.     

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

Background

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

Questions/purposes

We investigated whether there were differences in immunologic hypersensitivity reactions in retrievals from revised THAs with ceramic-on-polyethylene versus metal-on-metal bearing couples.

Patients and Methods

We compared newly formed capsule and periprosthetic interface membranes from revision surgery for aseptic failure from 20 patients with low-carbide bearings and 13 patients with ceramic-on-polyethylene bearings. For control tissue, we obtained samples from the hip capsule during the primary THA implantation in 13 patients with low-carbide bearings and seven with ceramic-on-polyethylene bearings. We examined the tissues with conventional histologic and immunohistochemical methods.

Results

Compared with tissue from the control subjects and patients with ceramic-on-polyethylene bearings, the tissues from patients with low-carbide metal-on-metal bearings were associated with (1) extensive necrosis and fibrin exudation in the newly formed hip capsule and (2) diffuse and perivascular lymphocytic infiltration of a higher degree than in the hips with ceramic-on-polyethylene bearings in conventional histologic examination, and (3) more T than B cells.

Conclusions

The conventional histologic and immunohistochemical findings in tissues retrieved from failed THAs with low-carbide metal-on-metal bearings are consistent with a link between hypersensitivity and osteolysis with low-carbide bearing couples.     

Hip Resurfacing versus Total Hip Arthroplasty: A Systematic Review Comparing Standardized Outcomes

Background

Metal-on-metal hip resurfacing was developed for younger, active patients as an alternative to THA, but it remains controversial. Study heterogeneity, inconsistent outcome definitions, and unstandardized outcome measures challenge our ability to compare arthroplasty outcomes studies.

Questions/purposes

We asked how early revisions or reoperations (within 5 years of surgery) and overall revisions, adverse events, and postoperative component malalignment compare among studies of metal-on-metal hip resurfacing with THA among patients with hip osteoarthritis. Secondarily, we compared the revision frequency identified in the systematic review with revisions reported in four major joint replacement registries.

Methods

We conducted a systematic review of English language studies published after 1996. Adverse events of interest included rates of early failure, time to revision, revision, reoperation, dislocation, infection/sepsis, femoral neck fracture, mortality, and postoperative component alignment. Revision rates were compared with those from four national joint replacement registries. Results were reported as adverse event rates per 1000 person-years stratified by device market status (in use and discontinued). Comparisons between event rates of metal-on-metal hip resurfacing and THA are made using a quasilikelihood generalized linear model. We identified 7421 abstracts, screened and reviewed 384 full-text articles, and included 236. The most common study designs were prospective cohort studies (46.6%; n = 110) and retrospective studies (36%; n = 85). Few randomized controlled trials were included (7.2%; n = 17).

Results

The average time to revision was 3.0 years for metal-on-metal hip resurfacing (95% CI, 2.95–3.1) versus 7.8 for THA (95% CI, 7.2–8.3). For all devices, revisions and reoperations were more frequent with metal-on-metal hip resurfacing than THA based on point estimates and CIs: 10.7 (95% CI, 10.1–11.3) versus 7.1 (95% CI, 6.7–7.6; p = 0.068), and 7.9 (95% CI, 5.4–11.3) versus 1.8 (95% CI, 1.3–2.2; p = 0.084) per 1000 person-years, respectively. This difference was consistent with three of four national joint replacement registries, but overall national joint replacement registries revision rates were lower than those reported in the literature. Dislocations were more frequent with THA than metal-on-metal hip resurfacing: 4.4 (95% CI, 4.2–4.6) versus 0.9 (95% CI, 0.6–1.2; p = 0.008) per 1000 person-years, respectively. Adverse event rates change when discontinued devices were included.

Conclusions

Revisions and reoperations are more frequent and occur earlier with metal-on-metal hip resurfacing, except when discontinued devices are removed from the analyses. Results from the literature may be misleading without consistent definitions, standardized outcome metrics, and accounting for device market status. This is important when clinicians are assessing and communicating patient risk and when selecting which device is most appropriate for individual patients.     

Impact of Raised Serum Cobalt Levels From Recalled Articular Surface Replacement Hip Prostheses on the Visual Pathway

Background

The articular surface replacement (ASR) was recalled in 2010 because of higher than expected revision rates. Patients reported symptoms of neurologic dysfunction including poor vision. This cohort study, using objective measurements, aimed to establish whether a higher incidence of visual function defects exists in ASR patients.

Outcomes of the Recalled Articular Surface Replacement Metal-on-Metal Hip Implant System: A Systematic Review

Background

The aim of this review was to synthesize the main findings of clinical studies that have evaluated outcomes of the articular surface replacement (ASR) Hip System.

Survival and functional outcome of the Birmingham Hip Resurfacing system in patients aged 65 and older at up to ten years of follow-up

Purpose

Limited evidence exists regarding the outcomes of hip resurfacing in elderly patients. The primary study aims were to determine the survival and functional outcome following Birmingham Hip Resurfacing (BHR) in patients ≥65 years at up to ten years of follow-up. Secondary aims were to explore factors affecting survival and functional outcome.

Methods

Between 1997 and 2012, data were prospectively collected on 180 BHR (162 patients; mean age 69.2 years; 62 % male) implanted by one designing surgeon. Mean follow-up was six (range one to 14.4) years with no loss to follow-up. Outcomes of interest were implant survival, functional outcome [Oxford Hip Score (OHS)] and radiological evidence of implant failure.

Results

Three hips were revised, giving an overall cumulative survival of 96.4 % [95 % confidence interval (CI) 90.3–100] at ten years. Survival of 111 male BHR was 98.9 % (95 % CI 94.8–100) at ten years (one revision) compared with 91.9 % (95 % CI 77.0–100) in 69 female BHR (two revisions). Survival was affected by age (p?=?0.014) and femoral head size (p?=?0.024) but not by gender (p?=?0.079). Median pre-operative OHS was 50.0 % [interquartile range (IQR) 37.5–68.8], improving to 4.4 % (IQR 0–10.4) postoperatively. Men had significantly better postoperative OHSs compared with women (median male OHS 2.1 % versus 6.3 % female OHS; p?=?0.021).

Conclusions

Good survival and functional outcomes were achieved with the BHR at ten years in men and women ≥65 years. Despite registry findings to the contrary, age alone should not be a contraindication for hip resurfacing in centres with expertise in this procedure.     

Prospective study on serum metal levels in patients with metal-on-metal lumbar disc arthroplasty

Purpose

Metal-on-metal total disc replacement is a recent alternative treatment for degenerative disc disease. Wear and corrosion of these implants can lead to local and systemic transport of metal debris. This prospective longitudinal study examined the serum chromium and cobalt levels in 24 patients with cobalt–chromium alloy metal-on-metal lumbar disc replacements.

Methods

Serum was assayed for chromium (Cr) and cobalt (Co) using high-resolution inductively-coupled plasma-mass spectrometry. Detection limits were 0.015 ng/mL for Cr and 0.04 ng/mL for Co.

Results

Median serum Co levels at pre-op, 3, 6, 12, 24, and 36-months post-op were 0.10, 1.03, 0.96, 0.98, 0.67, and 0.52 ng/mL, respectively. Median serum Cr levels were 0.06, 0.49, 0.65, 0.43, 0.52, and 0.50 ng/mL, respectively.

Conclusion

In general, these results indicated that serum Co and Cr levels are elevated at all postoperative time points and are of the same order of magnitude as those observed in well-functioning metal-on-metal surface replacements of the hip and in metal-on-metal total hip replacements at similar postoperative time points.