Metallosis after contemporary metal-on-metal total hip arthroplasty. Five to nine-year follow-up

BACKGROUND: Authors of recent studies have reported early periprosthetic osteolysis in patients who have been treated with a contemporary metal-on-metal total hip arthroplasty and have suggested that metal hypersensitivity associated with an immunologic response to metal may be of etiologic importance. We evaluated the results and histologic findings in patients who had undergone revision of a failed contemporary metal-on-metal total hip arthroplasty. METHODS: Two hundred and seventeen total hip arthroplasties (SL-Plus stem and Bicon-Plus cup) with a Sikomet metal-on-metal articulation were implanted in 194 consecutive patients, and the results were retrospectively reviewed at a mean of seventy-seven months postoperatively. Clinical follow-up with the Harris hip score and plain radiographic evaluation were performed. Periprosthetic tissues from fourteen hips that had undergone revision arthroplasty were subjected to histologic analysis. RESULTS: The mean Harris hip score improved from 45 points preoperatively to 88 points at the final evaluation. Fourteen hips (6.5%) were revised: nine because of aseptic loosening, two because of technical failure, and three because of septic failure. Histologic examination of the retrieved periprosthetic tissues from the eleven patients who had undergone revision because of aseptic loosening or technical failure 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 93% for the stem and 98% for the cup. CONCLUSIONS: Our findings are in agreement with those in recent publications and support the possibility that periprosthetic osteolysis and aseptic loosening in hips with a metal-on-metal articulation are possibly associated with hypersensitivity to metal debris. Prospective, comparative, randomized long-term studies are necessary to determine the cause(s) of loosening of prostheses with this particular articulation.     

Total hip arthroplasty with use of the Metasul metal-on-metal articulation. Four to seven-year results

BACKGROUND: Total hip replacements with a metal-on-metal articulation were commonly used until the mid-1970s; most were then abandoned in favor of hip replacement with a metal-on-polyethylene articulation. The reason for this change was primarily early cup loosening, which was more prevalent with these metal-on-metal designs than it was with metal-on-polyethylene designs. In the late 1980s, a metal-on-metal design with improved clearance (adequate space between the femoral head and the acetabular articulation surface to allow fluid film lubrication and clearance of any debris from within this joint), metal hardness, and reproducible surfaces was introduced by Sulzer Orthopedics in Switzerland. Orthopaedic surgeons were interested in this Metasul articulation because the contribution of polyethylene wear particles to the failure of total hip replacements had become evident. This study was undertaken to review the clinical performance of this implant and to determine if early acetabular loosening or revision and wear and osteolysis were prevalent. METHODS: Between 1991 and 1994, seventy patients (seventy hips) had a total hip replacement with the Metasul metal-on-metal articulation and a cemented Weber cup. Nine patients died less than four years after the replacement; none of these deaths were related to the operation. Five patients were not available for radiographic evaluation, but they were contacted and it was known that the hip was not painful and had not been revised. Fifty-six patients (fifty-six hips) had complete clinical and radiographic data four to 6.8 years after the operation, and they made up the study group. The patients were evaluated with use of the Harris hip score, a patient-self-assessment form, and radiographs. RESULTS: At an average of 5.2 years (range, four to 6.8 years) after the operation, the average total Harris hip score for the fifty-three patients who did not have a revision was 89.6 points (range, 62 to 100 points). The average Harris pain score was 41.0 points (range, 30 to 44 points), and the average Harris limp score was 9.4 points (range, 5 to 11 points). One patient had revision of a loose cup, but there were no other loose acetabular components in the series. Two patients had revision of the acetabular component because of dislocation. No patient had a loose or revised femoral component. Therefore, the mechanical failure rate was one (2 percent) of fifty-six patients. Thirty-six of forty-seven patients who completed the patient-self-assessment form rated their result as excellent; seven, as very good; two, as good; one, as fair; and one, as poor. Wear could not be measured on radiographs because of the metal-on-metal articulation. No hip had radiographic evidence of acetabular osteolysis and two hips had calcar resorption, but there was no other radiographic evidence of focal osteolysis. CONCLUSIONS: Our four to seven-year experience with this articulation surface indicates that the clinical results are similar to those of total hip replacements with a metal-on-polyethylene articulation. We believe that the Metasul articulation may have a role in reducing the wear that occurs with total hip replacement. The Metasul articulation appears to be particularly indicated for more active patients. A historical comparison with the reports in the literature of which we are aware indicated that the hips in our study had a lower rate of acetabular revision and loosening than did those with previous metal-on-metal designs and that they had no more acetabular loosening or osteolysis than did those with metal-on-polyethylene articulations followed for an average of five years.     

Serum chromium levels before and after revision surgery for loosened metal-on-metal total hip arthroplasty

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 residual metal articulation, the mean serum chromium levels before and after revision surgery were 2.53 microg/L and 0.46 microg/L, respectively. In the 2 patients who still had a metal articulation on the contralateral side, the mean serum chromium levels before and after revision surgery were 2.85 microg/L and 1.90 microg/L, respectively. Moderate serum chromium levels in patients with metal-on-metal total hip arthroplasty show a decrease after removal of the metal-on-metal articulation.     

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

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 in a painful total hip arthroplasty. We present the history, clinical findings and hip scores, radiology, serology, hip arthroscopy and aspirate results, labeled white cell scan, revision-hip findings, histology and clinical results of a typical patient with a hypersensitivity response to a metal-on-metal hip articulation, and how results differ from patients with an infected implant. A practical scheme to investigate patients with a possible hypersensitivity response to an implant is presented.     

Curved-stem Hip Resurfacing

Hip resurfacing is an attractive concept because it preserves rather than removes the femoral head and neck. Most early designs had high failure rates, but one unique design had a femoral stem. Because that particular device appeared to have better implant survival, this study assessed the clinical outcome and long-term survivorship of a hip resurfacing prosthesis. Four hundred forty-five patients (561 hips) were retrospectively reviewed after a minimum of 20 years' followup or until death; 23 additional patients were lost to followup. Patients received a metal femoral prosthesis with a small curved stem. Three types of acetabular reconstructions were used: (1) cemented polyurethane; (2) metal-on-metal; and (3) polyethylene secured with cement or used as the liner of a two-piece porous-coated implant. Long-term results were favorable with the metal-on-metal combination only. The mean overall Harris hip score was 92 at 2 years of followup. None of the 121 patients (133 hips) who received metal-on-metal articulation experienced failure. The failure rate with polyurethane was 100%, and the failure rate with cemented polyethylene was 41%. Hip resurfacing with a curved-stem femoral component had a durable clinical outcome when a metal-on-metal articulation was used.     

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

BACKGROUND: This is a prospective study. METHOD:. 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 55+/-9 years, (range 25-70 years). Seven ( 3%) patients did not return for their last follow-up evaluation for reasons unrelated to their hip operation. RESULTS: The mean follow-up was 52 months (range 37-92 months). The preoperative Harris hip score was 45+/-19 and increased to 96+/-4 postoperatively. The invalidity of the patients was significantly improved postoperatively ( p<0.001). In all, 97% of the patients were satisfied or very satisfied with the result of the operation. There was no aseptic loosening noted in this series. Revision was done in 6 (1.8%) hips because of septic loosening ( n=5, 1.5%) or technical error ( n=1, 0.3%) during implantation. Dislocation of the prosthesis occurred in the early postoperative period in 2 (0.6%) hips. Periarticular ossification was observed in 30% of the hips (5% Brooker grades III and IV), but without associated disability. During revision surgery, no macroscopic metalosis could be identified in the newly formed hip joint membrane; however microscopic evidence for metalosis (Mirra grades 1 and 2) was seen in all revised hips. The survival for Zweymueller screw socket and stem 7.6 years after implantation was 99.4% and 96.8%, respectively. CONCLUSIONS: This study showed that the short-term results of Zweymueller total hip arthroplasty with metal-on-metal articulation were just as satisfactory as those of a conventional polyethylene on ceramic articulation, while the metal-on-metal articulation does not seem to give rise to new problems or complications.     

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

Background  

Osteoarthritis of the hip is successfully treated by total hip arthroplasty with metal-on-polyethylene articulation. Polyethylene wear debris can however lead to osteolysis, aseptic loosening and failure of the implant. Large head metal-on-metal total hip arthroplasty may overcome polyethylene wear induced prosthetic failure, but can increase systemic cobalt and chromium ion concentrations. The objective of this study is to compare two cementless total hip arthroplasties: a conventional 28 mm metal-on-polyethylene articulation and a large head metal-on-metal articulation. We hypothesize that the latter arthroplasties show less bone density loss and higher serum metal ion concentrations. We expect equal functional scores, greater range of motion, fewer dislocations, fewer periprosthetic radiolucencies and increased prosthetic survival with the metal-on-metal articulation.     

Medium-term results of a modern metal-on-metal system in total hip replacement

Since 1988, metal-on-metal articulation from cobalt-chromium-molybdenum alloy was reintroduced into hip arthroplasty as an alternative to metal-on-polyethylene or ceramic-on-polyethylene components. Modular joint surfaces were developed for the second generation metal-on-metal articulation using newly introduced and proven prosthetic implants. Since 1990, 78 patients with 78 uncemented total hip replacements were followed up in a prospective study. The mean followup was 60 months. Three patients were lost to followup. The average age of the patients at the time of surgery was 48.8 years. Thirty-three patients had been operated on previously. No early infections occurred; one late infection occurred after 3 years. Dislocation of the prosthesis occurred in one patient who was lost to followup. In two patients ectopic ossifications were removed 17 and 27 months postoperatively. At revision surgery no metallosis could be identified. At the last followup examination, the Harris hip score was 96.8 points on average. There was no evidence that the metal-on-metal articulation gave rise to new problems or complications. Metal-on-metal articulation reduced wear considerably in the authors' previous experience. It is hoped that foreign body reactions are reduced significantly so that an alternative for total hip replacement in younger and active patients will be available.     

Long-Term Results of a Contemporary Metal-on-Metal Total Hip Arthroplasty : A 10-Year Follow-Up Study

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.     

Metal-on-metal bearing in hip prosthesis generates 100-fold less wear debris than metal-on-polyethylene

Aseptic loosening due to osteolysis in total hip replacement has been related to wear debris released from prosthetic components. Retrospective long-term observations of patients with the metal-on-metal prosthesis has shown long-term survivorship and good mechanical performance. Thus, the new and modified metal-on-metal prosthesis has been introduced on the market. Historical clinical data from the 1 st generation metal-on-metal hip prosthesis may not be relevant for the 2nd generation of metal-on-metal hip prosthesis. Therefore, preclinical testing of the prosthesis must be conducted before clinical evaluation.

We assessed the tribological performance of the metal-on-metal prosthesis versus the metal-on-polyethylene prosthesis introduced on the market as Metasul™ and Protasul™, respectively. In a 12-channel joint simulator, 6 metal-on-metal bearing and 3 metal on polyethylene prostheses were tested, with the same number of corresponding soak controls. The wear was assessed gravimetrically. The “steady-state” wear-rates from the metal-on-metal prosthesis were almost 100 times less than that from the metal-on-polyethylene prosthesis. The tribological wear performance of the metal-on-metal hip prosthetic system is promising.     

Metal-on-metal bearing in hip prosthesis generates 100-fold less wear debris than metal-on-polyethylene

Aseptic loosening due to osteolysis in total hip replacement has been related to wear debris released from prosthetic components. Retrospective longterm observations of patients with the metal-on-metal prosthesis has shown long-term survivorship and good mechanical performance. Thus, the new and modified metal-on-metal prosthesis has been introduced on the market. Historical clinical data from the 1st generation metal-on-metal hip prosthesis may not be relevant for the 2nd generation of metal-on-metal hip prosthesis. Therefore, preclinical testing of the prosthesis must be conducted before clinical evaluation. We assessed the tribological performance of the metal-on-metal prosthesis versus the metal-on-polyethylene prosthesis introduced on the market as Metasul and Protasul, respectively. In a 12-channel joint simulator, 6 metal-on-metal bearing and 3 metal on polyethylene prostheses were tested, with the same number of corresponding soak controls. The wear was assessed gravimetrically. The "steady-state" wear-rates from the metal-on-metal prosthesis were almost 100 times less than that from the metal-on-polyethylene prosthesis. The tribological wear performance of the metal-on-metal hip prosthetic system is promising.     

Cementless Metasul metal-on-metal total hip arthroplasties at 13 years

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 111 consecutive patients. The results were retrospectively reviewed at 13 years postoperatively. Clinical and radiographic evaluations and implant survivorship were performed. Seven hips (4.7%) were revised. The overall survivorship with revision for any reason as the end point was 0.94. The average Harris hip score was 91.4. Expansive osteolysis was found adjacent to the stem in 4 hips. Metal wear-related aseptic loosening was not the major reason for failure in our Metasul metal-on-metal THAs. Recurrent dislocation was the main reason for revision in our series.     

Serum cobalt levels after metal-on-metal total hip arthroplasty

BACKGROUND: Systemic cobalt dissemination from the Metasul Co-28Cr-6Mo-0.2C metal-on-metal total hip prosthesis has been demonstrated in the first year after implantation. The aim of this prospective study was to monitor the serum cobalt concentrations in patients during the first five years after total hip arthroplasty with a metal-on-metal articulation. METHODS: A total hip arthroplasty was performed without cement in 100 consecutive patients who had either unilateral osteoarthritis or unilateral osteonecrosis. Fifty patients were randomized to be treated with a metal-on-metal articulation, and fifty patients, with a ceramic-on-polyethylene bearing. The femoral stem was made of a Ti-6Al-7Nb alloy, and the threaded acetabular cup was made of commercially pure titanium. Blood samples were taken before the operation and at multiple time-points for five years after the operation. Serum cobalt concentrations were measured with use of atomic absorption spectrometry. RESULTS: In the metal-on-metal group, the median serum cobalt concentration was 1 micro g/L at one year after surgery and 0.7 micro g/L at five years. The median of the serum cobalt concentrations measured from three to twelve months did not differ from the median of subsequent measurements, with the numbers available. The median serum cobalt level in the control group of patients treated with the ceramic-on-polyethylene articulation was below the detection limit at all time-points. CONCLUSIONS: Systemic cobalt release from Metasul metal-on-metal articulations was demonstrated throughout the five-year study period. The median serum cobalt concentrations were found to be slightly above the detection limit and remained in a constant range. The serum cobalt concentrations did not reflect a so-called run-in wear period of the metal-on-metal articulations.     

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

Background Aseptic loosening is the major cause of implant failure. In cemented hip arthroplasty, failure of the acetabular side is mainly due to lysis caused by wear particles. By using an implant with low wear characteristics and by enhancing acetabular fixation using an uncemented implant, we aimed to reduce acetabular lysis and thereby loosening.

Patients and methods This was a retrospective cohort study of 119 hips (101 patients) that had the Uncemented Fitmore cup (Sulzer Orthopedics). In 66 patients, the femoral component was CF-30 (Sulzer) used with cement. In the remaining 35 patients, thrust plate prosthesis (TPP) (Sulzer) was used. Of the 101 patients, 94 (112 hips) were available for study. Mean follow-up of the 94 patients was 7 (5-13) years.

Results The mean preoperative Harris hip score was 38 and the mean postoperative Harris hip score was 89 at the last follow-up. Taking aseptic loosening as the endpoint, the survival rate of the Fitmore cup was 100% at 11 years.

Interpretation The uncemented Fitmore acetabular cup with second generation metal-on-metal articulation showed good results with regard to aseptic loosening in the medium term.     

The influence of resting periods on friction in the artificial hip

Insufficient tribologic performance of total joint components is a major cause of prostheses failure. Wear has been studied intensively using testing machines that apply continuous motions. Human locomotion, however, is not well represented by continuous motions alone. Singular events and resting periods are a substantial part of daily activities. Resting does influence adhesion in the artificial joint with possible effects on friction, wear, and loosening. The current study evaluated the effects of resting on the frictional properties of hip prosthesis components. The activity measurements of 32 patients with artificial hip replacements were analyzed for resting durations of the hip. A pin-on-ball screening device was used to determine friction after characteristic resting periods and during continuous oscillating motion. All common articulation pairings were investigated. Prolonged and frequent resting periods of the hip were found for the patients. Initial friction increased with increasing resting duration for all tested materials (between 41% and 191%). The metal-on-metal articulations showed the highest friction level (0.098 for sliding) and the highest increase (191%) in friction with resting duration (0.285 after resting periods of 60 seconds). A high static frictional moment after resting periods might present a risk for aseptic implant loosening. Therefore, large head diameters of metal-on-metal joints should be used with caution, especially when additional unfavorable risk factors such as obesity, weak bone-implant interface, or high activity level are present.     

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

Many previous reports suggest total hip arthroplasty performs suboptimally in young patients with osteonecrosis. We retrospectively compared the performance of metal-on-metal articulation in a select group of 107 patients with 112 hips (98 uncemented and 14 cemented stems) 60 years of age or younger with either osteonecrosis (27 patients, 30 hips) or primary osteoarthritis (80 patients, 82 hips). We evaluated all patients with patient-generated Harris hip score forms and serial radiographs. Five mechanical complications were caused by impingement, two with pain, two dislocations, and one liner dissociation. At a minimum followup of 2.2 years (mean, 5.5 years; range, 2.2-11.7 years), we observed no osteolysis or aseptic loosening in the osteonecrosis group, whereas one osteoarthritic hip had cup revision for loosening (none showed evidence of osteolysis). None of the stems were loose. Patients with osteonecrosis or primary osteoarthritis were similar in clinical and radiographic performance. The patients with metal-on-metal hip arthroplasty for osteonecrosis had no revisions for aseptic loosening, but did have one liner change in a cup for painful impingement.     

Cementless Metasul metal-on-metal total hip arthroplasty in patients less than fifty years old

BACKGROUND: Durable results of total hip arthroplasty have been difficult to achieve in young patients. We reviewed the intermediate-term clinical and radiographic results in a series of active, higher-demand patients who were less than fifty years old when they underwent cementless total hip arthroplasty with the use of the Metasul metal-on-metal articulation. METHODS: Seventy total hip arthroplasties were performed in sixty-two patients who were younger than fifty years of age (average age, thirty-seven years). Two patients (two hips) had had a resection arthroplasty because of deep infection less than five years postoperatively and were excluded. Sixty patients (sixty-eight hips) were available for complete clinical and radiographic analysis after a mean duration of follow-up of seven years. RESULTS: The mean preoperative Harris hip score of 49 points improved to 95 points at the time of final follow-up; fifty-six patients (93%) had an excellent result. No component was seen to be loose radiographically at the time of final follow-up. Only one focal area of pelvic osteolysis in one patient and two small focal areas of femoral osteolysis in another patient were identified. The hip with focal pelvic osteolysis underwent revision surgery with a liner change and bone-grafting of the osteolytic lesion around a stable component. CONCLUSIONS: At a mean of seven years after arthroplasties with a Metasul metal-on-metal articulation, there was a low rate of osteolysis and aseptic loosening in this group of young patients. However, additional follow-up is necessary to determine any possible long-term deleterious effects associated with this metal-on-metal articulation.     

Metal-on-metal resurfacing versus total hip replacement-the value of a randomized clinical trial

This article describes a randomized clinical trial in young patients, comparing metal-on-metal cemented resurfacing hip replacement with cemented total hip replacement. The trial was stopped early, mainly because of a high incidence of failure of the cemented resurfacing acetabular component. The results reinforce the importance of clinical trials for evaluating the safety and efficacy of prosthesis designs before being used in a large cohort of patients. Although there may be advantages of resurfacing hip replacement, trials are also required to demonstrate it has a midterm success that reasonably approaches that of total hip replacement.     

Metal-on-metal bearings and hypersensitivity in patients with artificial hip joints. A clinical and histomorphological study

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 periprosthetic tissues suggested the development of an immunological response. Therefore, in order to determine the relevance of these symptoms, we performed a study of the clinical data and periprosthetic tissues associated with endoprostheses with a metal-on metal articulation that had been retrieved at revision. METHODS: Periprosthetic tissues as well as the clinical data on the patients were obtained from the first nineteen consecutive revisions performed at the treating hospitals. At the time of the revision, fourteen patients had the metal-on-metal articulation exchanged for either an alumina-ceramic or a metal-on-polyethylene articulation. Five patients received another second-generation metal-on-metal total joint replacement. Five-micrometer sections were prepared from the tissue samples, were stained with routine and immunohistochemical methods, and were examined histologically. Histological specimens from three groups of patients, two of which were treated with non-metal-on-metal implants, served as controls. RESULTS: The majority of patients had persistence of their preoperative pain or early recurrence of the pain after the original total hip replacement, and often a pronounced hip joint effusion had developed after the original replacement. Radiographic follow-up showed the development of radiolucent lines in five hips and of osteolysis in another seven hips. At the revision surgery, both the cup and the stem were found to be well fixed in nine patients. The characteristic histological features were diffuse and perivascular infiltrates of T and B lymphocytes and plasma cells, high endothelial venules, massive fibrin exudation, accumulation of macrophages with droplike inclusions, and infiltrates of eosinophilic granulocytes and necrosis. Only a few metal particles were detected. Immunohistochemical analysis demonstrated that the cellular reaction was still active. The patients who received another second-generation metal-on-metal articulation at the time of the revision had no decrease in symptoms. In the control group of tissues obtained at revisions of endoprostheses without cobalt, chromium, or nickel articulations, there were no similar signs of immune reactions. CONCLUSIONS: These histological findings support the possibility of a lymphocyte-dominated immunological response. Although the prevalence of this reaction is low, the persistence or early reappearance of symptoms, including a marked joint effusion and the development of osteolysis, after primary implantation may suggest the possibility of such a reaction.