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

Long-term Follow-up on Revisions of a Recalled Large Head Metal-on-metal Hip Prosthesis: A Single Surgeon Series

Background

In 2010, a recall was issued for a specific monoblock large head metal-on-metal (MoM) hip prosthesis due to short-term revision rates of 12%-13% (articular surface replacement, DePuy Orthopaedics, Inc., Warsaw, IN). High complication, infection, and rerevision rates for revised MoM implants have been reported. The purpose of the study is to report long-term outcomes and trend metal ion levels of this recalled MoM prosthesis from a single surgeon series.

Methods

Retrospective chart review was performed on all patients that underwent revision of large MoM hip replacements between 2010 and 2015. Pre- and post-revision Harris Hip Score (HHS), cup abduction angles, anteversion angles, and cup sizes were compared. Survivorship and HHS were the primary outcomes measured; serum cobalt and chromium levels were secondary outcomes. Multivariate linear regression was used to examine the correlation between prerevision serum metal ion levels and HHS.

Results

A total of 24 hips (21 patients) met inclusion criteria. Mean time to revision was 4.12 years ± 1.1. Mean follow-up was 10.0 years (7-11.9 years). Mean HHS increased significantly after revision from 48.5 to 89.5 (P < .001). Higher prerevision cobalt levels were correlated with lower prerevision HHS (cobalt R = 0.25; chromium R = 0.3160). There was no correlation with prerevision cobalt (P = .2671) or chromium (P = .3160) with postrevision HHS. Most recent metal ion testing revealed a significant decrease in both cobalt (P = .0084) and chromium (P = .0115). Survival rate is 100%.

Conclusions

Our study showed excellent survivorship and outcomes at 10 years. There were no failures for any reason including infection. This differs from previous studies and confirms excellent long-term results are possible with revision of this recalled MoM implant.

Midterm Results of Contemporary Uncemented Total Hip Arthroplasty in Patients 45 Years or Younger

Total hip arthroplasty (THA) in young patients has varying results, and some reports show inferior results when compared with those of older patients. This study evaluated the outcomes of contemporary uncemented THA in patients 45 years or younger. This was a retrospective review from 2003 to 2015 at an academic institution. Three hundred one uncemented THAs in 232 patients 45 years or younger were evaluated. All patients had a minimum follow-up of 5 years. Ninety-day complications, survivorship free of revision, and dislocations were evaluated. Mean age was 35.7 years, 43.1% of patients were women, and mean follow-up was 9.3 years. Ninety-day complications included 26 emergency department visits, 11 readmissions, 3 revisions, and 3 dislocations. The rate of 10-year survivorship free of revision was 85.5%, and the rate of 10-year survivorship free of aseptic revision was 87.7%. Excluding metal-on-metal (MOM) THAs, 10-year aseptic survivorship was 93.3%. The most common reasons for revision were adverse local tissue reaction after MOM THA (16 hips) and periprosthetic joint infection (6 hips). In a multivariable logistic regression model, sickle cell disease (SCD) and conversion THA were associated with 90-day readmissions. Both MOM THA and SCD were associated with revision (P<.05). Patients who are 45 years or younger undergoing THA (excluding MOM articulation) had a rate of 10-year survival free of aseptic revision of 93.3%. At 9.3 years' mean follow-up, THA in young patients was associated with low revision rates with acceptable risk of prosthetic joint infection and dislocation. Patients with SCD are at increased risk for early readmission and revision at latest follow-up. [Orthopedics. 2023;46(1):e45-e51.].

Long-Term Outcome of Small Head Metal-On-Metal Total Hip Arthroplasty: A 15-to-22 Year Follow-Up

BACKGROUND

The Metasul articular interface was a second-generation metal-on-metal (MoM) total hip arthroplasty (THA) that was introduced as a promising interface with improved manufacturing technology, better clearances, and enhanced metal hardness. In December 2001, the manufacturer recalled these implants due to the failure of cup osseointegration.

METHODS

Between 1997 and 2004, 168 consecutive primary Metasul THAs were performed in 144 patients. Most patients received a cementless femoral and porous-coated acetabular component with 28 mm head. A competing risk analysis was performed for determination separately for bearing surface-related, recalled bearing failure, and end point revision for any reason. For clinical patient evaluation, we used Harris hip score and University of California at Los Angeles scores. Cobalt and chromium ion level measurement and standard radiographic assessment was performed.

RESULTS

Of the 168 THAs, 19 hips were revised at a mean period of 15 years as follows: 12 of them were due to recalled acetabular component, five hips had noninterface-related complication, and two true interface surface failure. The survival distribution function of all hips with revision for any reason was 88.4%, for bearing interface relation 98.8%, and 92.6% for recalled cups. The mean Harris hip score and University of California at Los Angeles scores were 85 and 6, respectively, and the median Co and Cr blood levels were 1.0 and 0.91 μg/L.

CONCLUSION

Excluding the recalled components, Metasul articular interface has performed extremely well at a minimum follow-up of 15 years in this relatively young population. There were two interface-related revisions in the entire cohort.

Highly Cross-Linked Polyethylene in Cementless Total Hip Arthroplasty in Patients with Previous Acetabular Fractures: A Minimum 5-Year Follow-Up Study

BACKGROUND

Outcomes of THA after acetabular fracture are generally less favorable than those of the nontraumatic arthritis due to a higher rate of cup loosening and osteolysis. We, therefore, investigated whether highly cross-linked polyethylene liners positively impact outcomes of THA in patients with posttraumatic osteoarthritis after acetabular fracture.

METHODS

We retrospectively evaluated 39 patients with previous acetabular fracture who underwent THA using highly cross-linked polyethylene liner after a mean 8.5 year follow-up. All procedures were performed at a single institution by a single surgeon using the same type of THA implants. Wear measurements were performed using a computer-assisted PolyWare software. Osteolysis was evaluated with use of radiography and computed tomography.

RESULTS

The mean preoperative Harris hip score was 44.4 points, which improved to 93.1 points at final follow-up. Neither femoral nor acetabular components displayed mechanical loosening and no components had been revised. Radiographs and CT scans did not demonstrate osteolysis. The mean linear wear was 0.043 mm/y (range 0-0.098 mm/y). With the data available, univariate regression analysis suggests that age, gender, weight, initial fracture type, the duration of follow-up, activity level, liner thickness, acetabular cup inclination, and the necessity of bone graft had no influence on liner penetration.

CONCLUSION

While the long-term effects of the polyethylene particles from highly cross-linked polyethylene remain unknown, implant survivorship and wear data in this study are promising for this high-risk population. Our encouraging results support the continued use of this type of polyethylene in patients after acetabular fractures.

LEVEL OF EVIDENCE

Level IV Therapeutic study.

Highly Cross-Linked Polyethylene in Total Hip Arthroplasty in Patients Younger Than 50 Years With Osteonecrosis of the Femoral Head: A Minimum of 10 Years of Follow-Up

BACKGROUND

Polyethylene wear and subsequent periprosthetic osteolysis remain a major concern of total hip arthroplasty (THA) failure in young, active patients with osteonecrosis of the femoral head (ONFH). The literature is lacking regarding the long-term performance of highly cross-linked polyethylene (HXLPE) in these patients. The purpose of this study is to evaluate long-term results for cementless THA using metal-on-HXLPE bearing couplings in patients younger than 50 years with ONFH.

METHODS

We retrospectively evaluated the clinical and radiographic results of a consecutive series of 85 THAs (in 67 patients) performed with HXLPE liners (Durasul) in patients younger than 50 years who had ONFH. All procedures were performed at a single institution by a single surgeon using the same type of implants. The minimum duration of follow-up was 10 years (mean, 13.5 years; range, 10-17.3 years). Wear was measured using computer software. Osteolysis was evaluated with the use of radiography and computed tomography.

RESULTS

The mean Harris hip score was 49.3 points (range, 26-68 points) before surgery, which improved to 93.6 points (range, 87-98 points) after surgery. Neither femoral nor acetabular components displayed mechanical loosening, and no components had been revised by the final follow-up evaluation. Radiographs and computed tomography scans did not demonstrate osteolysis. The mean liner wear was 0.037 mm/y (range, 0-0.099 mm/y). With the data available, univariate regression analysis did not demonstrate that age, sex, weight, activity level, underlying cause of osteonecrosis, liner thickness, or cup inclination had any influence on liner penetration.

CONCLUSION

Although the long-term effects of HXLPE particles remain unknown, the implant survivorship rate and wear rate in our study are promising and support the continued use of metal-on-HXLPE bearing couplings in these high-risk patients because they do not produce any of the issues associated with hard-on-hard couplings.

LEVEL OF EVIDENCE

Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

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

Background and purpose - Large metal-on-metal (MoM) articulations are associated with metal wear and corrosion, leading to increased metal ion concentrations and unacceptable revision rates. There are few comparative studies of 28-mm MoM articulations with conventional metal-on-polyethylene (MoP) couplings. We present a long-term follow-up of a randomized controlled trial comparing MoM versus MoP 28-mm articulations, focused on metal ions and implant survival. Patients and methods - 85 patients with a mean age of 65 years at surgery were randomized to a MoM (Metasul) or a MoP (Protasul) bearing. After 16 years, 38 patients had died and 4 had undergone revision surgery. 13 patients were unavailable for clinical follow-up, leaving 30 patients (n = 14 MoM and n = 16 MoP) for analysis of metal ion concentrations and clinical outcome. Results - 15-year implant survival was similar in both groups (MoM 96% [95% CI 88-100] versus MoP 97% [95% CI 91-100]). The mean serum cobalt concentration was 4-fold higher in the MoM (1.5 μg/L) compared with the MoP cohort (0.4 μg/L, p < 0.001) and the mean chromium concentration was double in the MoM (2.2 μg/L) compared with the MoP cohort (1.0 μg/L, p = 0.05). Mean creatinine levels were similar in both groups (MoM 93 μmol/L versus MoP 92 μmol/L). Harris hip scores differed only marginally between the MoM and MoP cohorts. Interpretation - This is the longest follow-up of a randomized trial on 28-mm MoM articulations, and although implant survival in the 2 groups was similar, metal ion concentrations remained elevated in the MoM cohort even in the long term.

Incidence of Adverse Reactions to Metal Debris From 28-mm Metal-on-Metal Total Hip Arthroplasties With Minimum 10 Years of Follow-Up: Clinical, Laboratory, and Ultrasound Assessment of 44 Cases

BACKGROUND

Total hip arthroplasty with metal-on-metal (MoM) bearings has been suspected to cause adverse reactions to metal debris (ARMD), with the incidence varying greatly by implant type and patient gender. The prevalence of ARMD from small-diameter MoM bearings in women is unknown, especially after 10 years of follow-up (FU).

METHODS

Cementless 28-mm MoM total hip arthroplasty bearings (Metasul) were implanted consecutively in 42 active women between 1996 and 2002. They were reviewed after a minimum of 10 years' FU with clinical, laboratory, radiological, and ultrasound assessments.

RESULTS

Mean FU was 15.9 years (range, 13-18). The mean Postel-Merle d'Aubigné and Oxford scores were 16.9 (range, 13-18) and 15.1 (range, 12-24), respectively, at FU. Mean cup inclination angle was 46.3° (range, 35°-57°). No femoral osteolysis was detected, but limited acetabular osteolysis (11%) over the screw holes occurred in 5 cases. No liquid or solid synovial reactions or ARMD were apparent on ultrasound, even in the 5 cases of pelvic osteolysis. Mean chromium levels were 1.32 μg/L (range, 0.1-7.9) and cobalt levels were 1.85 μg/L (range, 0.35-13.6). Cobalt was >3 μg/L in only 3 cases. The 15.9-year survivorship was 95% (range, 94.1%-98.9%).

CONCLUSION

Reliable results were obtained with 28-mm MoM bearings, notably in young, active patients. This implant configuration requires very accurate positioning. No ARMD was seen in this group at 16 years' FU.

Bousquet dual mobility socket for patient under fifty years old. More than twenty year follow-up of one hundred and thirty one hips

PURPOSE

The aim of this study was to analyze dual mobility cup survival rate on young patients under 50 years old at more than 20 years of follow up.

METHODS

One hundred thirty seven hips with a first generation of dual mobility Bousquet cup (Serf) were included. The mean age at the time of the surgery was 41 years and the mean follow-up was 21.9 years.

RESULTS

Twenty year follow-up cup survival rate was 77%. No dislocation occurred, 44 hips were revised (including 21 cup aseptic loosenings isolated, 15 Intra Prosthetic Dislocations), seven hips were lost to follow-up, 11 patients died, and 75 hips were still in situ.

CONCLUSION

First generation dual mobility cup survival on young patient was comparable with literature results. The main complications, cup aseptic loosening and intra prosthetic dislocation, were wear-related. With improvements of the defects of first generation dual mobility, we might expect an even better survival rate with contemporary DM cups.

Metal on Metal or Ceramic on Ceramic for Cementless Total Hip Arthroplasty: A Meta-Analysis

BACKGROUND

Hard bearings, metal on metal (MOM) and ceramic on ceramic (COC), have been developed to overcome polyethylene wear-related osteolysis, but comparisons between these 2 hard bearings are limited. We performed a meta-analysis to determine revision rates for (1) any reason, (2) aseptic loosening, (3) periprosthetic joint infection (PJI), and (4) recurrent dislocation between MOM and COC bearings in cementless total hip arthroplasty.

METHODS

This analysis included 3 studies comparing COC and MOM bearings and 56 studies reporting outcomes of MOM or COC bearings. We conducted a comparison meta-analysis (with a fixed-effects model) on the 3 comparative studies and a proportional meta-analysis on the data from the 59 articles to determine a consensus.

RESULTS

In the comparison meta-analysis, MOM showed higher revision rate than COC for any reason (odds ratio = 2.39, P = .046) and PJI (odds ratio = 6.21, P = .015). In the proportion meta-analysis, the MOM group showed significantly higher revision rate than COC group for any reason, aseptic loosening, and PJI.

CONCLUSION

MOM bearings were associated with a higher risk of revision for any reason and PJI than COC bearings after cementless total hip arthroplasty.

The Diagnosis of Infection in Metal-on-Metal Hip Arthroplasties

BACKGROUND

Distinction of aseptic from septic hip arthroplasty failure can be challenging. Some studies report an increased incidence of septic failure with metal-on-metal (MoM) hip arthroplasties. The Musculoskeletal Infection Society (MSIS) have formulated criteria to facilitate the diagnosis of periprosthetic joint infection (PJI). In this study, we determined the prevalence and histologic features of septic MoM hip failure.

METHODS

Overall, 104 cases of failed MoM hip arthroplasty, classified as septic or aseptic by MSIS microbiological criteria, were analyzed. The overall prevalence of septic failure was determined and the nature of the causative organisms noted. The extent of the neutrophil polymorph (NP) infiltrate in periprosthetic tissue in all cases was analyzed by hematoxylin-eosin and chloroacetate esterase staining.

RESULTS

The prevalence of septic MoM hip arthroplasty failure was 6.7%. Infective organisms were coagulase-negative Staphylococcus in 4 cases; Staphylococcus aureus, Streptococcus, and Propionibacterium species were isolated in the remaining cases. Chloroacetate esterase staining facilitated identification of NPs. All cases of PJI contained more than 5 NPs per high-power field (HPF) on average. Four cases of aseptic MoM implant failure contained scanty or scattered NPs (less than 5 per HPF on average).

CONCLUSION

The prevalence of PJI as a cause of MoM hip arthroplasty failure was relatively high compared to other hip bearing combinations; however, the organisms responsible were similar. Histologically, a minority of aseptic MoM implant failures contained some NPs, but the MSIS criteria for the histologic diagnosis of PJI (>5 NPs/HPF) correctly identified all microbiologically confirmed cases of septic failure.

Hip arthroplasty for treatment of advanced osteonecrosis: comprehensive review of implant options, outcomes and complications

Surgical treatment for late stage (post-collapse) osteonecrosis of the femoral head is controversial. In these situations, the outcome of joint preservation procedures is poor. There are several arthroplasty options for late-stage disease. The clinical outcomes of hemiarthroplasty and hemiresurfacing are unpredictable because of progressive acetabular cartilage degeneration. Total hip resurfacing may be associated with further vascular insult to the femoral head and early failure of the implant. Total hip replacement with metal-on-conventional polyethylene bearing surfaces has been the gold standard, but implant survivorship is limited in young active patients due to wear and osteolysis. Newer alternative bearing surfaces may have improved wear characteristics, but their durability must be confirmed in longer-term studies.

Mid-term clinical results of total hip arthroplasty using a Wagner standard cup for dysplastic hip

BACKGROUND

The outcome of cementless total hip arthroplasty depends on many factors. We must not forget fundamental things those are design of outer surface of the component, that leads bone ingrowth into the prosthesis, better initial stability, and better insertional techniques. The purpose of this study was to review our experience with metal-on-metal total hip arthroplasty with a Wagner standard cup for patients who had acetabular dysplasia.

PATIENTS AND METHODS

Fifty-four patients with 55 hips underwent primary metal-on-metal total hip arthroplasty (Metasul prosthesis) with a Wagner standard cup (44-48 mm in outer diameter) and were followed for a minimum of 10 years. All patients received the same type of cementless femoral component (Natural hip stem) and femoral head (28 mm in diameter).

RESULTS

Seventeen of the 55 Wagner standard cups (30.9%) showed aseptic loosening over a mean period of 3.6 years after surgery, and there were no bone anchors on the outer surface of the 16 retrieved cups.

CONCLUSION

From our experience, the small Wagner standard cup does not achieve sufficient osteointegration and we do not recommend the use of this cup, especially for patients with acetabular dysplasia and/or those with a small stature.

Study of the polycarbonate-urethane/metal contact in different positions during gait cycle

Nowadays, a growing number of young and more active patients receive hip replacement. More strenuous activities in such patients involve higher friction and wear rates, with friction on the bearing surface being crucial to ensure arthroplasty survival in the long term. Over the last years, the polycarbonate-urethane has offered a feasible alternative to conventional bearings. A finite element model of a healthy hip joint was developed and adjusted to three gait phases (heel strike, mid-stance, and toe-off), serving as a benchmark for the assessment of the results of joint replacement model. Three equivalent models were made with the polycarbonate-urethane Tribofit system implanted, one for each of the three gait phases, after reproducing a virtual surgery over the respective healthy models. Standard body-weight loads were considered: 230% body-weight toe-off, 275% body-weight mid-stance, and 350% body-weight heel strike. Contact pressures were obtained for the different models. When comparing the results corresponding to the healthy model to polycarbonate-urethane joint, contact areas are similar and so contact pressures are within a narrower value range. In conclusion, polycarbonate-urethane characteristics are similar to those of the joint cartilage. So, it is a favorable alternative to traditional bearing surfaces in total hip arthroplasty, especially in young patients.

A comparative study of four bearing couples of the same acetabular and femoral component: a mean follow-up of 11.5 years

We present a retrospective evaluation of 1369 hip arthroplasties performed using the Bicon-Plus cups and SL-Plus stems, differing only in the bearing combination. Four bearing combination groups were used: metal-on-polyethylene (MoP) group with 587 hips, ceramic-on-polyethylene (CoP) group with 161 hips, metal-on-metal (MoM) group with 322 hips and ceramic-on-ceramic (CoC) group with 299 hips. The mean follow-up was 11.5 years (4.1 to 15.0). Radiological evaluation was performed on implants failed due to aseptic loosening. The survival for prosthesis with revision for any reason at ten years was 96.1% (95% confidence interval (CI) 94.3 to 97.9) for MoP, 98.1% (CI 95.9 to 100) for CoP, 90.2% (CI 86.8 to 93.6) for MoM, and 95.6% (CI 93.0 to 98.2) for CoC. Survival for aseptic loosening was also determined.

High rate of revision and a high incidence of radiolucent lines around Metasul metal-on-metal total hip replacements: results from a randomised controlled trial of three bearings after seven years

A total of 397 hips were randomised to receive Metasul metal-on-metal (MoM), metal-on-conventional polyethylene (MoP) or ceramic-on-polyethylene (CoP) bearings using a cemented triple-tapered polished femoral component (MS-30). There were 129 MoM hips in 123 patients (39 male and 84 female, mean age 63.3 years (40.7 to 72.9)), 137 MoP hips in 127 patients (39 male and 88 female, mean age 62.8 years (24.5 to 72.7)) and 131 CoP hips in 124 patients (51 male and 73 female, mean age 63.9 years (30.6 to 73.8)). All acetabular components were cemented Weber polyethylene components with the appropriate inlay for the MoM articulation. Clinical evaluation was undertaken using the Harris hip score (HHS) and radiological assessments were made at two, five and seven years. The HHS and radiological analysis were available for 341 hips after seven years. The MoM group had the lowest mean HHS (p = 0.124), a higher rate of revision (p < 0.001) and a higher incidence of radiolucent lines in unrevised hips (p < 0.001). In all, 12 revisions had been performed in 12 patients: eight in the MoM group (four for infection, four for aseptic loosening, three in the MoP group (one each of infection, dislocation and pain) and one in the CoP group (infection). Our findings reveal no advantage to the MoM bearing and identified a higher revision rate and a greater incidence of radiolucent lines than with the other articulations. We recommend that patients with a 28 mm Metasul MoM bearing be followed carefully.

Pooled outcome of total hip arthroplasty with the CementLess Spotorno (CLS) system: a comparative analysis of clinical studies and worldwide arthroplasty register data

PURPOSE

Our aim was to elucidate the pooled outcome of the CementLess Spotorno (CLS) system in total hip arthroplasty (THA).

METHODS

We compared the outcome of clinical inventor studies, independent clinical studies, and worldwide register data. The main endpoints for analysis were revision rates.

RESULTS

Twenty clinical studies were evaluated and, with one exception, overall found revision rates largely in line with register data. Revision rates (revisions per 100 observed component years) range from 0.15 (inventor study) to 0.28 (independent studies) and 0.43 (register datasets).

CONCLUSION

Data of journal publications and register datasets using the CLS system do not differ significantly with respect to revision rates. Only the initial inventor study reports a revision rate three times lower than in pooled worldwide register datasets.

Metasul vs Cerasul bearings: a prospective, randomized study at 9 years

The aims of our study were to compare metal-on-metal (Metasul) and ceramic-on-ceramic (Cerasul) bearings and to evaluate the clinical and radiographic results of these 2 different hard-on-hard bearings. We conducted a prospective, randomized study on a series of 250 cementless primary total hip arthroplasties. The prostheses were similar in all aspects except for the bearing surfaces: 50% of Metasul bearing and 50% of Cerasul bearing. All the patients were evaluated both clinically and radiographically. No patient was lost to follow-up. Clinical outcomes in both groups were similar. Considering aseptic loosening as the end point for failure, the 9-year survival rate was 100% for Cerasul and 98.4% for Metasul. Neither bearing outperformed the other both radiographically and clinically. The overall 9-year survival rate was 99.2% and 97.6% in the Cerasul and Metasul groups, respectively.

Recurrence of dislocation following total hip arthroplasty revision using dual mobility cups was rare in 180 hips followed over 7 years

BACKGROUND

Dual mobility (DM) cups of mobile polyethylene were introduced to prevent total hip arthroplasty (THA) dislocation, but no large series with this design to treat recurrent instability have been reported.

PURPOSE

Our retrospective investigation ascertained the efficiency of DM cups in correction of recurrent dislocation and assessed any adverse effects.

METHODS

One hundred eighty THAs with recurrent instability were revised to DM cups in 180 patients (mean age, 67.4 ± 11.7 years; range, 19 to 92 years). Thirty-one patients (17.2%) underwent at least one earlier THA revision, and 15 (10.3%) incurred non-union of the greater trochanter. Of the initial group in 2009, 145 patients had completed evaluations which included assessment of the Harris Hip Score and a radiographic assessment at a mean follow-up of 7.7 ± 2.2 years (range, 4 to 14 years). The rate of survival was calculated considering any reason for revision as failure.

RESULTS

At follow-up, Harris hip score was 83.9 ± 16.1 (range, 21 to 100). Dislocation of the large articulation occurred in seven hips (4.8%), and only two recurred (1.4%) (one requiring additional revision). In addition, two intra-prosthetic dislocations of the small articulation (1.4%) were observed and needed revision surgery. The large number of earlier surgeries and non-union of the greater trochanter were related to recurrent instability. Two cups (1.4%) showed signs of definite loosening; six (4.1%) presented signs of possible loosening. Twenty-nine hips manifested femoral or acetabular osteolysis (20%), but only three were severe. Eight-year survival rate considering revision for any reason was 92.6% (95% CI, 85.5-96.4%).

CONCLUSIONS

This series indicates that DM cups are a viable option to treat recurrent THA instability. Their design provides a low risk of recurrent instability without increasing mechanical complications.

Bearing surface considerations for total hip arthroplasty in young patients

Bearing selection for total hip arthroplasty in young patients is important because of the likely long service life of the implant. Careful consideration of the next operation is recommended when choosing components. No prospective, randomized studies exist that document the clear superiority of any bearing couple in young, active patients. Modern metals, ceramics, and polyethylenes all hold promise. Further long-term data on modern bearings are needed to determine the clinical performance of these bearings. This article summarizes the available data on various bearing couples in patients aged younger than 50 years.

Survivorship of second-generation metal-on-metal primary total hip replacement

BACKGROUND

Second generation metal-on-metal total hip replacements (THR) were introduced in the late 1980s and various studies reported conflicting data on their outcome.

METHODS

Implant survival of 1,270 second-generation 28 mm metal-on-metal primary THR in 1,121 patients followed prospectively at a mean of 6.8 years postoperatively was evaluated retrospectively. The probability of survival at 10 years was estimated using the method of Kaplan and Meier, and relative risk factors including age, gender, BMI, type of implant fixation and component size were calculated using the Cox proportional-hazards model.

RESULTS

Sixty-three (5%) THRs were revised, these being 28 hips for aseptic loosening and 35 for reasons other than aseptic loosening. The probability of survival at 10 years, with revision for any reason as the endpoint, was 0.90 (95% confidence interval (CI) 0.86-0.94) for the THR as a whole, 0.91 (95% CI 0.87-0.95) for the cup, and 0.96 (95% CI 0.94-0.98) for the stem. No demographic factors or covariates were found to significantly affect the implant survivorship.

DISCUSSION

As there was no superior probability of survival, and there have been concerns on putative local and systemic toxicity of metal debris, the use of second-generation metal-on-metal articulations for primary THR remains moot.

Minimum 5-year results of modular metal-on-metal total hip arthroplasty

This study reports minimum 5-year results of 95 hips implanted with a Pinnacle (DePuy, Warsaw, Ind) modular metal-on-metal acetabular prosthesis. Clinical scores such as the Harris Hip and Western Ontario and McMaster Universities Arthritis Index revealed excellent clinical outcomes at mean 6-year follow-up. With the use of large-diameter femoral heads, dislocation was rare, occurring in only 1 hip. Moreover, no acetabular and only 3 femoral osteolytic lesions were detected. Kaplan-Meier survivorship at 7 years after arthroplasty was 97.8% for the total hip arthroplasty construct and 100% for the acetabular shell. No unexplained pain or other complication attributable to wear debris or the metal-on-metal articulation was observed. These findings indicate that total hip arthroplasty with this specific modular metal-on-metal bearing performed well in a high-demand population at midterm follow-up.

Total hip arthroplasties in young patients under 50 years: limited evidence for current trends. A descriptive literature review

We examined all reported outcomes of uncemented and cemented total hip arthroplasty in patients younger than 50 years of age listed in Medline (1966- 1 January 2009) and PubMed, and scrutinised reference lists of relevant papers. In addition, we evaluated relevant data in the Swedish hip arthroplasty register. 109 relevant articles were identified, 37 of which had a mean follow-up longer than 10 years. Although uncemented implants are widely used in patients under 50 years of age, there are only 2 reports that fulfil the criteria published by the National Institute for Clinical Excellence (NICE) in the United Kingdom (follow-up of >10 yrs and survival of =90%). Current trends relating to implant selection remain unsupported by survival data, and additional information about the long-term results of newer implants is essential. As matters stand, the most reliable results relate to cemented implants.

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.

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

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, 23-59 years) at the time of surgery. Osteonecrosis of the femoral head accounted for most diagnoses. Harris Hip Scores and hip range of motion both significantly improved (p<0.001) at an average follow-up of 32.6 months (range, 24-48 months). Only one intraoperative calcar fissure was encountered, and it was fixated by cerclage wiring; there was no infection, dislocation, or osteolysis around either the cup or the stem at the latest follow-up. A postoperative gap in the acetabular component was noted in 24 hips, with a mean depth of 1.11 mm, but this was not correlated with the functional score (p=0.291). Transient thigh pain, which resolved after 6 months, was observed in six patients but was not related to either the postoperative gap or cup inclination (p=1.000 and p=0.664, respectively). All patients resumed their original jobs and recreational activities with little discomfort. Thus far, large-head metal-on-metal total hip arthroplasty has shown excellent early results. The long-term results and the effects of metal debris and potentially elevated serum metal ion levels require further observation.

Cementless total hip arthroplasty with a metal-on-metal bearing in patients younger than 50 years

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 reviewed cementless metal-on-metal THAs in 70 patients (78 hips) with a mean follow-up of 12.4 years. Metasul articulation was used with the Wagner acetabular component in all. Survivorship with revision for any cause was 98.7% (95% confidence interval, 98%-100%), and survivorship due to the development of osteolysis for any lesion was 97.5% (95% confidence interval, 95%-99%). Mean Harris hip score improved from 51 to 95 points at final follow-up. The findings of this study indicate that outcomes of cementless THA with a metal-on-metal bearing in young patients are satisfactory. However, longer-term studies in larger cohorts are required to determine whether metal-on-metal articulations are really a favorable option in young patients.

Primary hip arthroplasty with 28-mm Metasul articulation

This follow-up study reports on 69 patients at mean 13 years with total hip arthroplasty using 28-mm Metasul (Zimmer, Winterthur, Switzerland) metal-on-metal articulation. These results are not transferable to large-diameter head metal-on-metal articulations. Four new revisions, 3 for disassociation of the liner and 1 for mechanical loosening of the acetabulum, occurred since the previous report of mean 7.3 years. The prevalent cause of late revision is disassociation, which suggests a high frictional torque or impingement in these articulation surfaces. No revision was done for osteolysis. Overall, of the original 127 hips, 116 (91%) were known to have maintained their original components.

Cementless metal-on-metal versus ceramic-on-polyethylene hip arthroplasty in patients less than fifty years of age: a comparative study with twelve to fourteen-year follow-up

BACKGROUND

We previously reported the outcomes of a case-control study, at a minimum of five years of follow-up, comparing metal-on-metal and ceramic-on-polyethylene bearings for cementless primary hip arthroplasty in active patients below the age of fifty years. This report is an update on these groups after a minimum duration of follow-up of twelve years.

METHODS

Thirty-nine metal-on-metal cementless hip replacements with a 28-mm-diameter Metasul articulation were compared with a control group that included thirty-nine cementless ceramic-on-polyethylene hip replacements performed with a 28-mm-diameter head. The Metasul group included thirty patients with a mean age of forty years (range, twenty-three to forty-nine years), and the control group included thirty-two patients with a mean age of forty-one years (range, fifteen to forty-nine years). The groups were matched for age, activity level, preoperative Harris hip score, acetabular cup diameter, and indication for hip arthroplasty. All patients had a high level of activity, with 82% rated as grade IV or V according to the Devane scale.

RESULTS

After a mean duration of follow-up of thirteen years (twelve to fourteen years), only one hip (3%) had asymptomatic acetabular osteolysis and no hip (0%) had been revised in the metal-on-metal group, whereas eighteen hips (46%) had osteolysis and eleven hips (28%) had been revised because of wear or osteolysis in the ceramic-on-polyethylene group (p < 0.003). In the metal-on-metal group, the median Co concentration in the whole blood was 0.95 μg/L (0.4 to 4.8 μg/L) and the median Cr concentration was 1.2 μg/L (0.1 to 5.6 μg/L). The twelve-year survival rate (with reoperation for any reason as the end point) was 100% in the metal-on-metal group and 70% (95% confidence interval, 63% to 77%) in the ceramic-on-polyethylene group (p = 0.003).

CONCLUSIONS

After twelve to fourteen years of follow-up, metal-on-metal implants demonstrated better radiographic and survival results than ceramic-on-polyethylene implants in young, very active patients. Current wrought metal-on-metal implants with a 28-mm-diameter head and high carbide concentration did not produce the high rates of osteolysis and allergic reactions that may be observed with cast low-carbide metal-on-metal bearings after a shorter duration of follow-up.

Metal-on-metal cups cemented into reinforcement rings: a possible new acetabular reconstruction procedure for young and active patients

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 = .01): no revision was undertaken for aseptic loosening or fixation failure. Considering reoperation and bearing revision as end points, survival rates were 95.8% and 100%, respectively. The mean blood concentrations of chromium, cobalt, and titanium were 1.85 μg/L, 1.24 μg/L, and 9.62 μg/L, respectively. A longer follow-up is mandatory, but it seems possible to use hard-on-hard bearings with metallic rings in young patients during hip revisions or in dysplastic cases with encouraging intermediate follow-up results.

Squeaking sound in total hip arthroplasty using ceramic-on-ceramic bearing surfaces

PURPOSE

To evaluate the causes and frequency of the squeaking sound in ceramic-on-ceramic THA.

MATERIALS AND METHODS

This study included 61 hips of 50 patients who underwent ceramic-on-ceramic THA in our hospital from March 1999 to April 2005. The average age at the time of operation was 57.6 years. The average duration of follow-up was 69.5 months. Three different acetabular components were used: Osteonics (Stryker, USA: 24 cases), Bicontact (Aesculap, Germany: 27 cases) and ABG (Howmedica, UK: 10 cases).

RESULTS

Fourteen (22.9%) of the 61 cases had a squeaking sound, and this sound started a mean of 47.57 months after the operation. Except in one case, the squeaking sound remained until the last follow-up. There was no difference in acetabular component position between the squeaking and nonsqueaking groups. The squeaking sound was found to be related to the BMI (body mass index) and cup design. It occurred frequently in patients with high BMI who had received a total hip arthroplasty using an Osteonics cup. Among 11 of the patients, squeaking occurred while squatting, and in 3 patients while walking. Six patients suffered from mild restrictions on their activities of daily living, and 8 had more than moderate restrictions with squeaking sounds.

CONCLUSION

A squeaking sound in THA using ceramic-on-ceramic surfaces is not a rare complication, and often affects the patient's behavior.

Optimal bearing surfaces for total hip replacement in the young patient: a meta-analysis

Although there is general consensus about the efficacy of total hip replacement (THR) in young patients, the most appropriate bearings in young patients remain highly debated. The three most popular bearings in use include metal-on-polyethylene (MOP), metal-on-metal (MOM) and ceramic-on-ceramic (COC). We conducted a systematic review and meta-analysis of literature to summarise the best available evidence on relative success of the three most popular bearings used in THR in young active patients. Our findings support the use of MOM bearings in the management of the young arthritic hip. These findings, largely based upon observational studies, should be taken in the context of the limitations of such non-randomised study designs.

Metal-on-metal total hip arthroplasty

The effects of elevated levels of metal ions in patients who have undergone metal-on-metal total hip arthroplasty are not fully understood. The effects of femoral head size on serum metal-ion levels have been the subject of conflicting reports, and further investigation is needed to evaluate the impact of acetabular and femoral component alignment. The conduct of clinical trials of metal-on-metal total hip arthroplasties has been inadequate as few investigators have used a randomized controlled design to compare metal-on-metal bearings with other bearing surfaces. Additional clinical research needs to include appropriate validated patient-reported outcome measures, activity monitoring, and health economics.

Cementless acetabular socket revisions using Metasul metal-on-metal bearings

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 Hip Scores improved from 56 to 92 points. No hip required further revision for aseptic loosening. Focal femoral osteolysis newly developed in zone I in 1 hip, which was treated by curettage and bone grafting. The authors suggest that second-generation metal-on-metal bearings in cementless acetabular socket revisions can achieve good medium-term clinical and radiographic results.

Custom cementless stem improves hip function in young patients at 15-year followup

THA in young patients is challenging regarding restoration and survival because patients are young, active, and tend to have disturbed anatomy. We asked whether a three-dimensional custom cementless stem could restore hip function, decrease osteolysis and wear, and enhance stem survival in young patients. We retrospectively reviewed 212 patients (233 hips) younger than 50 years (mean, 40 years) at a followup of 5 to 16 years (mean, 10 years). The Merle D'Aubigné-Postel and Harris hip scores improved at last followup. No thigh pain was recorded for any of the patients; 187 of the 212 patients (88%) had full activity recovery, 206 had full range of motion, and 151 had a score greater than 80 points for all five categories of the Hip disability and Osteoarthritis Outcome score. Five patients had femoral osteolysis not associated with pain. With revision for any reason as an end point, the survivorship was 87% (range, 77%-97%) at 15 years, and considering stem revision only, the survivorship was 93% (confidence interval, 90%-97%) at 15 years. Our data compare favorably with those from series using standard cementless stems at the same followup with a high percentage of patients achieving functional restoration and a low rate of complications.

LEVEL OF EVIDENCE

Level IV, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.

Failure of the Durom Metasul acetabular component

Large-diameter metal-on-metal articulations reportedly provide better stability and range of motion than smaller diameter bearings. We therefore asked whether a large-diameter (44- to 50-mm) metal-on-metal articulation (Durom) would eliminate dislocation and provide similar functional scores and clinical and radiographic failure rates as those with 28-mm articulation. We prospectively followed 181 patients (207 hips) who had a large-diameter articulation implanted between May 2006 and November 2007. We compared these patients with a historical control of 54 patients who had a small-diameter (28-mm Metasul) articulation. All patients had a Harris hip score and a self-assessment of outcome and radiographic followup. The minimum followup was 1 year (mean, 1.6 years; range, 1-2 years). During the followup period, we performed revisions on 29 patients (30 hips [15%]) with 21 of 29 (72%) having radiographic criteria of loosening. Thirteen retrieved cups and acetabular tissue were examined histologically. Twenty-eight of 151 unrevised patients had radiographic impending failure; 12 without revision had clinical failure. Eight patients (nine hips) had both clinical failure and impending radiographic failure. Cup inclination was 41.3 degrees +/- 5.4 degrees and anteversion was 20.2 degrees +/- 7 degrees. The revision rate and quality of clinical results were unacceptable as compared with our historical controls. We do not recommend use of the Durom implant.

LEVEL OF EVIDENCE

Level IV, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.

Cementless cups do not increase osteolysis risk in metal-on-metal total hip arthroplasty. Apropos of 106 cases

BACKGROUND

Metal-on-metal bearings in total hip arthroplasty (THA) were introduced to reduce the production of wear debris and debris-induced periprosthetic osteolysis. Analysis of various series according to the type of selected acetabular fixation highlights different evolutions: favourable results with uncemented cups contrasting with loosening and radiolucent lines (RLL) evolution for cemented cups.

HYPOTHESIS

Combining metal-on-metal bearings to uncemented cups does not increase the osteolysis risk at a minimum 5 years' follow-up.

MATERIALS AND METHODS

From January 1999 to December 2002, 106 Metasul THAs were implanted in 95 patients using a Hardinge anterolateral approach (40 women and 55 men with an average age of 59.2 years). The cups were of cementless, hydroxyapatite-coated Cedior type (Zimmer) housing a Metasul insert in a polyethylene sandwich. The femoral stem used was the cemented Acora, then the Exafit (Zimmer) type with Metasul 28-mm head mounted on a 8/10 Morse taper. Patients were evaluated clinically using the Postel-Merle-d'Aubigné (PMA) scoring system and radiologically using various markers: cup inclination angle, eventual RLL presence, appearance of osteolysis images, ectopic ossifications and finally, eventual implant migration. In the eventuality of suspected RLL evolution or osteolysis, advanced imaging was performed; joint aspiration liquid and cobalt serum level were studied.

RESULTS

We reviewed 94 prostheses (85 patients) with an average follow-up of 6.4 years (4.3 to 9.3 years, median of 6.3 years). The rate of patient loss from follow-up and death was 12.1%. The PMA score of non-revised patients increased from 11.4+/-1.5 to 17.6+/-0.2 at follow-up. We numbered ten re-operations not attributable to the type of bearings used. Three revisions were directly related to the metal-on-metal bearing: two metallosis due to impingement and one case of hypersensitivity. Cup inclination angle was 45.7+/-5.49 degrees . No implant migration was noted during the follow-up duration. Only one cup undergoing revision presented a substantial osteolysis. On the femoral side, with non-revised implants, we observed 13 cement/bone RLL images around nine femoral stems and six calcar resorptions. The survival rate at more than 6 years was 95.8% (91.8-99.8) for the cups and 94.8% (90.3-99.2) for the femoral stems (95% confidence interval).

DISCUSSION

The present study confirms our hypothesis: with Metasul bearings equipped cementless cups, the rates of aseptic loosening, RLL or acetabular osteolysis are low and remain stable over time, unlike the results observed for Metasul series with polyethylene directly cemented on bone. Specific complications, such as metallosis due to impingement and hypersensitivity, can rarely be encountered. These results encourage us to continue employing metal-on-metal bearings with non-cemented cups in active patients.

LEVEL OF EVIDENCE

Level IV: Therapeutic study.

Cementless femoral components in young patients: review and meta-analysis of total hip arthroplasty and hip resurfacing

The study purpose was to analyze current results of modern cementless femoral components in young patients having total hip arthroplasty (THA) or hip resurfacing. Twenty-two studies (n = 5907; hips = 6408) evaluating modern cementless THA in young patients and 15 studies evaluating hip resurfacing (n = 3002; hips = 3269) were included. Meta-analysis techniques were used to pool failure rates. The pooled failure rate for THA using femoral revision for mechanical failure as an end point was 1.3% (95% confidence interval [CI], 1.0%-1.7%) at a mean 8.4 years of follow-up. At a mean of 3.9 years of follow-up, the pooled mechanical failure rate of the femoral component for hip resurfacing was 2.6% (95% CI, 2.0-3.4). In conclusion, the enthusiasm for hip resurfacing should be tempered by these data. Longer follow-up and direct comparison trials are required to confirm these findings.

Increased metal allergy in patients with failed metal-on-metal hip arthroplasty and peri-implant T-lymphocytic inflammation

BACKGROUND

In 16 patients with revised metal-on-metal arthroplasty and peri-implant lymphocytic inflammation, we verified the role of metal hypersensitivity by patch testing (PT) and lymphocyte transformation test (LTT).

METHODS

In the 16 patients with lymphocyte dominated periprosthetic inflammation, allergy history was obtained by a questionnaire, specific serum IgE to aeroallergens was measured to assess atopy, PT to standard and metal series was performed and metal sensitivity was further assessed by LTT using blood mononuclear cells.

RESULTS

Revision surgery was performed because of pain (8/16), osteolysis (4/16), dislocation (3/16) and loosening of the stem (1/16). Histological examination showed perivascular infiltrates of T lymphocytes, high endothelial venules, fibrin exudation and accumulation of macrophages with drop-like inclusions. Five patients had a history of cutaneous metal allergy and atopy was found in 25% of the patients. In 13/16 patients (81%), systemic metal sensitivity was found based on PT and/or LTT. Patch test reactions were seen in 11/16 patients (69%; partly multiple reactions/patient): 7/16 to Cobalt (Co), 7/16 to Chromium (Cr), 4/16 to Nickel (Ni), and one each to Molybdenum (Mo) and Manganese (Mn). Ten of 16 patients (62%) showed enhanced LTT reactivity to metals: 7/16 to Ni, 7/16 to Co, 5/16 to Cr, 5/16 to Mo and 4/16 to Mn.

CONCLUSIONS

The lymphocyte dominated peri-implant inflammation may well reflect an allergic hyper-reactivity in these patients, given the high rate of concomitantly found metal allergy. Despite the overall incidence of metal implant allergy being low, allergic reactions should be included as differential diagnosis in failed metal-on-metal arthroplasty.

Influence of cup orientation on the wear performance of metal-on-metal hip replacements

There are a number of factors that determine the overall outcome of total hip replacement (THR) surgery, some of which appear to be related to the surgical procedure. In particular, the inclination angle at which the acetabular component is placed has been reported to influence the long-term successful performance of THR. The present study assessed the influence of cup orientation on the wear of 40 mm diameter metal-on-metal (MoM) hip bearings tested in a hip simulator. The bearings had a mean radial clearance of 150 microm; the cups oriented at 35 degrees, 50 degrees, and 60 degrees to the horizontal were loaded for up to 6 x 10(6) cycles. In each test the wear rates during the run-in phase were higher than in the steady state phase; the wear rates during the run-in phase were not significantly different for each cup orientation. However, at cup angles of 50 degrees and 60 degrees, the steady state wear rates were 0.69 mm3/ 10(6) cycles and 1.7 mm3/10(6) cycles respectively, significantly higher than at 35 degrees (0.24 mm3/10(6) cycles). The results indicated that larger cup inclination angles not only move the position of the wear scar but also, more significantly in MoM bearings, increase the wear rates and total wear volume generated.

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

This study examined the long-term results of a metal-on-metal total hip replacement with a Metasul-lined cup. Twenty-nine total hip arthroplasties were performed in 27 young patients (mean age 49 years). Twenty-two patients (23 hips) were available for clinical and radiographic analysis after a mean duration of 99 months. Mean preoperative Harris hip score of 60 improved to 93 at most recent follow-up. One patient required revision of his cup for periacetabular osteolysis. Radiographic analysis showed osteolysis in another four hips. The high rate of osteolysis found in this series has not previously been reported with this type of implant. The length of follow-up in this series is greater than other reports in the literature and may explain this difference.

[Metal-on-metal hip replacement using Metasul cups cemented into Muller reinforcement rings after a mean 5-year (3-8) follow-up: improvement of acetabular fixation by comparing with direct cementation to bone]

PURPOSE OF THE STUDY

Early loosening, before a three-year follow-up, has been observed with cemented cups having a metal-on-metal insert in a polyethylene cup. The metal-on-metal bearing has been incriminated as the source of the problem because of its rigidity (particularly for small cups measuring less than 50 mm) and the creation of stress conditions unfavorable for a cemented fixation. The purpose of this retrospective study was to determine whether this phenomenon is observed when the cement is fixed not directly into the bone, but via a Muller reinforcement ring.

MATERIAL AND METHODS

From 1998 to 2004, 23 arthroplasties using a cemented Metasul cup in a reinforcement ring were implanted in 22 patients (16 women and six men) aged on average 44 years (range 24-56 years). The series included six primary total hip arthroplasties (three for dysplasia, two for protrusions, one for rheumatoid arthritis and one for arthritic degradation) and seventeen revisions (two septic). The Metasul cup (Zimmer-Centerpulse) combined a 28 mm modular head anchored in a femoral implant (two cemented, 21 pressfit) and a polyethylene cup with a Metasul insert (13 of 23 measuring<50mm). In all cases, the cup was fixed with low-viscosity cement in a Myller metal reinforcement ring fixed with screws (Zimmer-Centerpulse). All patients were reviewed clinically and radiographically at a mean 5-year follow-up (range 3-8 years). Acetabular and femoral fixation were analysed (search for lucency and implant migration).

RESULTS

Revision was not necessary in any patient for failure of the acetabular fixation. The mean Postel-Merle-d'Aubigné score improved from 12.9 points (range 7-17) to 17.5 points (range 16-18). The radiographic analysis did not reveal any sign of lucency between the cup and ring, nor any migration of the ring. There was no evidence of femoral osteolysis but one femoral revision was needed due to fracture of the lateral cortical identified six weeks after implantation.

DISCUSSION AND CONCLUSION

Cementing the metal-on-metal cup into a reinforcement ring can avoid the risk of loosening observed after direct cementing into bone. In our study, the large number of small cups (13/23) would have been expected to produce a high rate of acetabular lucent lines and/or a high rate of early revision, as reported by others, as early as 24 months. Our series was also different from others by the use of pressfit femoral implants in most patients, which should reduce the risk of cement debris in the bearing. Longer follow-up will be necessary to confirm the good results observed to date which suggest that direct cementing of the cup into the bone should be incriminated rather than the metal-on-metal bearing to explain the reported failure of cemented Metasul cups.

Cementless total hip arthroplasty with alumina bearings in patients younger than fifty with femoral head osteonecrosis

BACKGROUND

There are conflicting reports with respect to the outcomes of total hip arthroplasties with ceramic bearings in young patients with osteonecrosis of the femoral head. We prospectively investigated the outcomes after cementless total hip arthroplasties with contemporary alumina bearings in patients with osteonecrosis of the femoral head in this age group.

METHODS

We prospectively followed sixty patients (seventy-one hips) with a mean age of 39.1 years for an average of 7.1 years. All procedures were performed at the same institution by one surgeon, and the results were evaluated serially. The clinical evaluations included use of the Harris hip score, and activities of daily living were evaluated with use of the criteria of Johnston et al.

RESULTS

The mean Harris hip score was 97.0 points at the time of final follow-up. Thirteen patients (fourteen hips, 20%) reported noise in the hip. Loosening or osteolysis was not observed in any hip, and no prosthesis had been revised. No hip had dislocated, and no ceramic fracture had occurred.

CONCLUSIONS

After a minimum of six years of follow-up, this cementless total hip arthroplasty with contemporary alumina bearings was found to be a promising procedure for young, active patients with osteonecrosis of the femoral head. However, we remain concerned about the long-term implications of the noise that was reported in these hips.

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.

THA using metal-on-metal articulation in active patients younger than 50 years

The main concern of patients with longer life expectancies and of patients who are younger and more active is the longevity of their total hip arthroplasty. We retrospectively reviewed 83 cementless total hip arthroplasties in 73 patients implanted with metal-on-metal articulation. All patients were younger than 50 years old (average age, 41 years) at the time of the index procedure, and 80% of the patients had an activity level graded 4 or 5 when measured with the system of Devane et al. A 28-mm Metasul articulation was used with three different cementless titanium acetabular components. At the most recent followup (average, 7.3 years), the average Merle d'Aubigné-Postel score improved from a preoperative 11.1 points to 17.4 points. We observed no radiographic evidence of component loosening. Ten acetabular components had lucency limited to one zone. The 10-year survivorship with the end point of revision (ie, exchange of at least one prosthetic or bearing component) was 100% (95% confidence interval, 90%-100%). Metasul bearings with cementless acetabular components remain promising in this high-risk younger patient population. However, additional followup strategies are recommended to determine any possible long-term deleterious effects associated with the dissemination of metallic ions.

LEVEL OF EVIDENCE

Level IV, therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence.

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.

[Early aseptic loosening of cemented cup in metal-on-metal total hip arthroplasties]

PURPOSE OF THE STUDY

The aim of this study was to report cases of acetabular failure of metal-on-metal total hip arthroplasties using cemented cups with a metal-metal bearing.

MATERIAL AND METHODS

From 1997 to 1999, 137 patients underwent total hip arthroplasty with a 28-mm head and a metal-metal (Metasul) bearing. At mean follow-up of three years eight months (range 2-6 years), three patients had died and thirteen were lost to follow-up or had less than 2 years follow-up. The analysis thus included 118 patients (122 hips) 67 women and 51 men (mean age 61 years). The same transgluteal approach with two cemented implants (Palacos gentamycine) was used in all patients. The Postel-Merle-d'Aubigné score was used for clinical assessment with search for lucent lines in the Delee and Charnley zones and cup migration on the standard x-rays. Actuarial survival curves were drawn using revision and failure as the end events.

RESULTS

In this series, there were no cases of dislocation or infection but there were five revisions for aseptic cup loosening: one at two years, two at four years, and two at five years. Among the remaining 117 implants, outcome was clinically very good in 101, good in 10 and fair in 6. Radiologically, there were no cases of femoral lucent lines, migration or osteolysis. For the cup, a lucent line measuring less than 1 mm and stable was observed in 81 hips. A progressive lucent line was observed in 18 hips with 11 showing signs of probable loosening. The five-year survival using surgical revision as the endpoint was 94%. Using cup failure (revision and progressive line), it was 80%. Revisions and radiographically probable loosenings were statistically more significant in small cups measuring 44 and 46 mm.

DISCUSSION

In this series, cemented metal-on-metal bearings showed a rate of failure greater than observed in metal-polyethylene implants and metal-on-metal implants using a press fit cup. Other series using a metal-on-metal bearing with a cemented cup have found the same trend.

CONCLUSION

We have discontinued this type of implant and recommend avoiding direct cementing of the polyethylene-metasul cup on the bone for total hip arthroplasty. The metal-on-metal bearing can still be used, but without cementing the cup.

Arthroplastie de hanche à couple métal-métal sur polyéthylène cimenté

PURPOSE OF THE STUDY

Metal-on-metal bearings in total hip arthroplasty may, in theory, provide an effective answer to osteolysis in active patients. The purpose of this retrospective study was to evaluate the results of a consecutive series of Metasul total hip arthroplasties with a cemented socket.

MATERIAL AND METHODS

The series was composed of 28 total hip arthroplasties in 23 patients (13 women and 10 men). The mean age at operation was 44 +/- 8.3 years (range 22-59 years). The initial diagnosis was osteoarthritis (14 hips), osteonecrosis of the femoral head (11 hips) and rheumatoid arthritis (3 hips). Cemented cups with a metal articulation surface molded into the polyethylene were used. The cup was articulated with a 28-mm metallic head. Cemented stems were used in 27 hips, whereas a hydroxyapatite coated stem was implanted in one hip.

RESULTS

One hip required revision for deep infection five months postoperatively. One patient (one hip) was lost to follow-up. Twenty-six hips were evaluated at an average 31-month follow-up (range 12-47 months). All hips were rated excellent or very good. Radiographically, seven hips (27%) had a progressive acetabular radiolucent line, including three complete radiolucent lines. The latter always were located at the bone-cement interface. No implant migration was noted. In these cases, the mean socket diameter was lower than for the rest of the cohort (p < 0.001).

DISCUSSION AND CONCLUSION

Progression of acetabular radiolucent lines remains of concern in this series of Metasul artificial hips. It is hypothesized that the diminution of polyethylene thickness has led to an increased rigidity of the socket, resulting in a higher rate of constraints at the bone-cement interface. Special attention must be given to these hips.

Clinical experience with metal-on-metal total joint replacements: Indications and results

Survivorship of total joint arthroplasty depends on the durability of fixation and durability of articulation. The metal-on-polyethylene articular couple has been the most widely used. Polyethylene wear (and the associated cytochemical events that culminate in osteolysis) has been identified as a major factor adversely influencing the durability of joint replacement. This stimulated the orthopaedic community to explore the possibility of using alternative bearings with lower wear rates.

Hard-on-hard bearings have been shown to be associated with reduced wear. Metal-on-metal bearings have wear rates that are 20-100 times lower than metal on conventional polyethylene. However, patients with metal-on-metal articulations have increased levels of cobalt and chromium in the serum and urine, and this has raised concerns about toxicity, mutagenesis, and hypersensitivity. At this stage there is no epidemiological evidence to suggest that the risk of carcinogenesis is anything more than theoretical.

Successful long-term results have been reported with the cast cobalt-chromium metal-on-metal couples of the mid-1960s. Tissues retrieved at revision of these implants did not show the giant-cell inflammatory response associated with polyethylene particles. Several researchers have reported excellent mid-term results with the current generation of high-precision metal-on-metal bearings.