SL-Plus Stem Research Articles

The Migration Pattern of a Cementless Hydroxyapatite-Coated Titanium Stem under Immediate Full Weight-Bearing-A Randomized Controlled Trial Using Model-Based RSA.

(1) Background: High primary stability is important for the long-term survival of cementless femoral stems in total hip arthroplasty (THA). The objective of this study was to investigate the migration pattern of a hydroxyapatite-coated cementless hip stem developed for minimally invasive surgery using model-based radiostereometric analysis (RSA). (2) Methods: In this randomized controlled trial, 44 patients with an indication for cementless primary THA were randomly allocated to receive either the SL-PLUS MIA stem, developed for minimally invasive surgery, or the SL-PLUS stem (Smith & Nephew Orthopaedics, Baar, Switzerland) which served as a control group. Unlimited weight-bearing was permitted postoperatively in both groups. Model-based RSA was performed after six weeks and after 3, 6, 12 and 24 months postoperatively. (3) Results: Mean total stem subsidence at two-year follow-up was 0.40 mm (SD 0.66 mm) in the SL-PLUS group and 1.08 mm (SD 0.93 mm) in the SL-PLUS MIA group (p = 0.030). Stem subsidence occurred during the first six weeks after surgery, indicating initial settling of the stem under full weight-bearing. Both stem designs showed good osseointegration and high secondary stability with no further migration after initial settling. (4) Conclusions: Settling of a cementless straight femoral stem occurs during the first six weeks after surgery under full weight-bearing. Although initial stem migration was higher in the SL-PLUS MIA group, it had no influence on secondary stability. All implants showed good osseointegration and high secondary stability with no signs of implant loosening during this two-year follow-up period.

Does hydroxyapatite coating enhance ingrowth and improve longevity of a Zweymuller type stem? A double-blinded randomised RSA trial.

An ongoing discussion is whether using a hydroxyapatite coating enhances the ingrowth and longevity of a femoral stem in total hip arthroplasty. The best way to predict speed of ingrowth and long-term outcome is by evaluating micromotion by radiostereometric analysis. To study the effect of hydroxyapatite (HA) coating on the migration of the SL-PLUS hip stem, we performed a prospective double blind randomised controlled trial comparing the early migration of the hydroxyapatite (HA)-coated SL-PLUS stem compared to the Standard (non-coated) SL-PLUS stem. 51 patients were randomly assigned to receive either an uncoated or a HA-coated femoral component during total hip replacement. RSA images were obtained direct postoperatively and at 6 weeks, 12 weeks, 6 months, 12 months and 24 months. HOOS scores were obtained preoperative and at final follow-up. RSA evaluation demonstrated significant migration up to 3 months postoperatively in both groups. After initial setting no significant migration was observed. There was no significant difference in migration between the HA-coated group and the uncoated group. Both Harris Hip Score (HHS) and HOOS domain scores (pain and ADL) significantly improved compared to baseline at 24 months after surgery in both treatment groups (p<0.001 for all comparisons). Improvement did not differ significantly between the 2 groups. At 2 years follow-up, the HA-coated and uncoated Zweymuller type, distal fitting stem do not show different migration patterns.

Outcome of the Cementless Zweymüller BICON-PLUS Cup and SL-PLUS Stem in the Very Elderly Individuals.

Introduction:There is current debate about which type of total hip prosthesis implants are best for the elderly patient. Implanting uncemented total hip arthroplasty (THA) in elderly people remains contested. The aim of present study was to evaluate the outcome of the uncemented Zweymüller BICON-PLUS THA in those with a minimum of 80 years of age.Materials and Methods:A retrospective data collection was performed in a regional teaching hospital in the Netherlands. The primary outcome of interest was the operation-free period. Secondary outcomes included the revision rates of the femoral and acetabular components and postoperative complications of the procedure. After a follow-up of at least 7 years, the surviving patients were reviewed on functionality using validated scores (Hip Disability and Osteoarthritis Outcome Score, Timed Up and Go, and Harris Hip Score) and radiographic analysis.Results:Between January 1999 and September 2004, 124 patients (128 THAs), aged 80 years and older, received an uncemented THA with a BICON-PLUS cup and SL-PLUS stem. The overall operation-free period was 6.5 years. One case of loosening of the cup was found among participants, with a survival rate of 99.2% of the BICON-PLUS cup in the analyzed group. In all, 28.8% of this group could be followed for a postoperative period of at least 7 years. The remainder of the patients died prior to the end of the 7-year period. Of these, 16.0% were eligible for clinical review. This group showed good function without evident signs of prosthetic loosening.Conclusion:The uncemented Zweymüller THA system, with threaded BICON-PLUS cup and SL-PLUS stem, showed good results, compared to outcome of other THA systems in elderly individuals. Therefore, it is a reliable option in older patients requiring THA.

Survival, clinical and radiological outcome of the Zweymüller SL/Bicon-Plus total hip arthroplasty: a 15-year follow-up study.

The primary aim of this study is to analyse the long-term results of the third generation of the "Zweymüller" total hip arthroplasty (THA) comprising the SL-Plus Stem and the Bicon-Plus cup. We evaluated 208 patients with a SL/Bicon-Plus primary THA (218 hips). Survival analysis was performed with a follow-up of 13 to 15 years. Complementary clinical and radiological analysis was performed using the "Hip Injury and Osteoarthritis Outcome Score" (HOOS) and x-rays of the hips. The probability of survival of the stem and cup with revision for any reason was respectively 0.96/0.97 at 10 years and 0.92/0.94 at 15 years. The probability of survival of the stem and cup with revision for aseptic loosening was respectively 0.99/0.97 at 10 years and 0.95/0.94 at 15 years. Clinical assessment of the patients, reported by the HOOS, were scored with a median for the subdivisions: symptoms 90%, pain 93%, function in daily activity 87%, function in leisure or sport 75%, and quality of life with 75%. Periprosthetic radiolucent lines were observed in half of all hips in Gruen zones 1 and 7. Mean linear wear of the polyethylene was 1.8 mm which corresponds to 0.12 mm/year. 2/3 of the hips show heterotopic ossifications, mostly Brooker type 1 and 2. The "third generation" Zweymüller total hip arthroplasty consisting of the SL stem and the Bicon cup has good long term results in terms of survival, clinical and radiological outcome.

Comparison of minimally invasive approach versus conventional anterolateral approach for total hip arthroplasty: a randomized controlled trial

It is a general belief among hip surgeons that minimally invasive surgical (MIS) approach for implantation of a total hip arthroplasty (THA) allows an improved and faster postoperative rehabilitation because of reduced muscle and soft-tissue damage, less postoperative pain and blood loss, and shorter hospital stay compared with conventional approaches. In the published relative literature though, there are controversial reports and debates on this matter. To our knowledge, there is no study on the medium-term functional results comparing MIS and traditional approaches for total hip replacement. The purpose of this prospective comparative controlled study was to compare MIS with conventional approach, on terms of pain, blood loss, and functional recovery over a follow-up period of 4 years. In a total of 90 consecutive randomly selected adult patients, who suffered from unilateral primary hip osteoarthritis, a cementless Zweymüller-Plus THA (SL-Plus stem, Bicon screw socket) was implanted by a single senior orthopedic hip surgeon in one institution in the same period. Forty-five patients (group A) were operated using an MIS anterolateral, short incision, muscle-sparing approach and 45 (group B) with a conventional (anterolateral modified Watson-Jones) approach under partial detachment of gluteus medius and minimus. Anthropometric data, blood loss, short-form 36 questionnaire, visual analog scale pain score, and walking endurance were included in the analysis. Approach-related surgical complications (trochanter major fracture, Bicon malposition) were recorded. Data were collected postoperatively and at 4-year follow-up. Two patients of group A and eight patients of group B were excluded from the final analysis. Thus, 80 patients were eligible for the final evaluation 4 years postoperatively. Postoperative pain score was less in the MIS group. However, no differences in perioperative blood loss, functional outcome, and walking endurance were shown between groups. No difference in Bicon cup implantation angle was measured in postoperative roentgenograms between group A and B patients, no intraoperative trochanter fracture occurred in any patient of both groups. The present prospective randomized study revealed no significant mid-term clinical and functional benefit for patients who underwent a THA through an MIS in comparison with those who were managed with a conventional open approach.

Low aseptic loosening and revision rate in Zweymüller-Plus total hip arthroplasty with ceramic-on-ceramic bearings

A recent comparative study reported lower revision rate and higher survival in ceramic-on-ceramic (CoC) than in metal-on-metal (MoM) coupling in Zweymüller-Plus THA. We retrospectively studied 87 consecutive patients (94 hips), who primarily received Zweymüller-Plus THA (SL-Plus stem, ceramic 28-mm ball head, Bicon cup) with third-generation CoC bearing surfaces for osteoarthritis. Survival, revision and osteolysis rate were studied and compared to those observed in historical series from this institution with the same THA and MoM articulation. The mean ± SD follow-up was 7.4 ± 1.7 years (range 6-10 years). Four hips (4%) in four patients were revised 1-6 years following primary implantation: one (1%) for aseptic loosening of SL-Plus stem and Bicon 5 years after index surgery; one (1%) for malpositioning of the Bicon and recurrent dislocations 1 year following implantation; and two (2%) for septic loosening 1 and 6 years postoperatively. Intraoperatively on inspection, there were neither findings for impingement in the revised hips, nor fracture of the Bicon ceramic inlay and ball head. Expansile osteolysis was shown around SL-Plus stem and Bicon in the revised for aseptic loosening hip. With revision of any component for aseptic loosening as the endpoint, the survival was 99% (95% CI 91-100%), while for revision for any reason, it was 95% (95% CI 87-98%) at 10 years. Zweymüller-Plus THA with CoC bearings showed, at mid-term follow-up, high survival and low revision rate for aseptic loosening. These rates were better than the historical series of the same THA with MoM articulation performed by the same surgeon. Level IV.

Poor Mid-Term Survival of the Low-Carbide Metal-on-Metal Zweymüller-Plus Total Hip Arthroplasty System

Between 1994 and 1999, 217 metal-on-metal total hip arthroplasties with a low-carbide bearing surface were performed with use of the cementless Zweymüller SL-Plus stem and the Bicon-Plus threaded cup in 194 consecutive patients. After a minimum follow-up of ten years, 181 living patients (203 hips) were available for evaluation. The revision rate after an average of twelve years was 18% (thirty-six hips in thirty-six patients were revised). The main reason for revision was aseptic loosening of one or both components. The probability of survival of the stem at fifteen years was 77% (95% confidence interval [CI], 65% to 86%). The probability of survival of the cup was 80% (95% CI, 62% to 90%). These high failure rates at mid-term follow-up led us to abandon the use of low-carbide metal-on-metal total hip arthroplasty components.

Analysis of bone mineralization on uncemented femoral stems by [18F]-fluoride-PET

Purpose We present the first study using fluoride-positron emission CT (F-PET/CT) to analyze mineralization of bone in the femur adjacent to uncemented stems following total hip arthroplasty (THA). We studied patients who were operated bilaterally for osteoarthritis with 2 different stems during the same surgical session.Patients and methods THA was performed bilaterally during the same surgical session in 8 patients with bilateral osteoarthritis of the hip. An SL-PLUS stem was inserted in one hip and a BetaCone stem was inserted in the contralateral hip, with randomization of side and sequence. A second group of 12 individuals with a normal healthy hip was used as reference for normal bone metabolism. Clinical and radiographic evaluation was performed preoperatively, postoperatively, and at 2 years. We used [18F]-fluoride-PET/CT to analyze bone mineralization adjacent to the stems 1 week, 4 months, and 12 months after surgery. We modified the Polar Map system to fit the upper femur for analysis and presentation of the PET results from 12 regions of interest adjacent to the whole stem.Results The clinical results were good at 2 years. By radiography, all stems were stable. At PET analyses 1 week after surgery, the activity was higher for the SL-PLUS group than for the BetaCone group. The activity was statistically significantly higher for both stems than the reference values at 4 months, and was most pronounced in the upper femur. At one year, the activity had declined more for the BC group than for the SL group.Interpretation The bone mineralization activity varied between different regions for the same stem and between different time periods for each group. F-PET/CT is a novel and valuable tool for analysis of bone mineralization patterns around uncemented femoral stems in detail. The combination of PET/CT analysis and the modified Polar Map system may provide a useful tool for future studies of metabolic bone responses to prosthetic implants.

Comparing Alumina-Reduced and Conventional Surface Grit-Blasted Acetabular Cups in Primary Tha: Early Results from a Randomised Clinical Trial

Alumina grit-blasted implants have been widely used in cementless total hip arthroplasty (THA). However, alumina particles can become embedded in the implant surface, leading to deposition in periprosthetic tissues and implant wear. We hypothesised that the alumina-reduced surface BICON-PLUS NT acetabular cup would improve implant fixation and clinical outcomes over the conventional surface BICON-PLUS cup. In a randomised controlled, double-blind study, patients with primary or secondary osteoarthritis requiring primary arthroplasty were randomly assigned to THA with either the BICON-PLUS or BICON-PLUS NT cup. All cups were combined with the SL-PLUS stem. In addition to clinical and radiographic assessments, dual-energy X-absorptiometry (DEXA) was performed preoperatively and at regular intervals during a planned 2-year follow-up period to measure bone mineral density as a marker of implant fixation. At 1 year, there were no differences in bone mineral density, or in clinical or radiographic outcomes between the BICON-PLUS and BICON-PLUS NT groups were identified, leading to early termination of the study. Both groups showed excellent clinical improvement and there were few complications. Both the alumina-reduced and conventional surface acetabular cups can be used with confidence in primary THA for osteoarthritis, although longer-term studies are required to confirm these findings.

The outcome of the cementless tapered SL-Plus stem: an analysis of arthroplasty register data

The aim of this study is to evaluate the outcome of the cementless SL-Plus stem in worldwide arthroplasty register datasets. A structured analysis was conducted the registered data about the SL-Plus stem manufactured by Smith&Nephew including published data from Australia as well as previously unpublished datasets from the Registers of Lombardia, Italy and Valdoltra, Slovenia. A total of 75% of the data analysed had not been published so far. The primary outcome measure was the revision rate, calculated in revisions per 100 observed component years. We evaluated a total of 10,684 primary and 122 revision surgeries with an average follow-up period of four years. All datasets showed good and reproducible results for treatment with the SL-Plus stem. An average of 0.31 revisions per 100 observed component years had been reported, which is considerably below the worldwide average (1.29) found for total hip arthroplasty independent of the product. The results of a large centre did not essentially deviate from the revision rates in Lombardia, where the numbers of cases per department are relatively low on average. There were no indications for product defects or relevant errors in application. The SL-Plus stem can be considered a high-quality product that ensures good results also in the hands of less experienced surgeons. Data from even young registers can substantially contribute to the assessment of implants, even with the short follow-up periods. These datasets particularly allow for valid assessment of safety issues and can therefore make an essential contribution to the solution of problems of current relevance.

High medium-term survivorship and durability of Zweymüller-Plus total hip arthroplasty

The Zweymüller-Plus system (SL-Plus stem, Bicon-Plus threaded cup) for primary total hip arthroplasty (THA) was introduced in 1993, as a successor of the Alloclassic THA with a few modifications in the conical stem shape and a new biconical threaded cup with a spherical shape. The medium-term performance of this system is not well established. To better understand the potential impact these design changes have had on (1) survivorship, (2) implant stability and (3) periprosthetic osteolysis, we studied patients who underwent THA using the SL-Plus stem and Bicon-Plus. We retrospectively reviewed the cases of 148 patients (153 hips) who underwent Zweymüller-Plus primary THA after an average of 11 years. With revision for aseptic failure of biological fixation as the endpoint, survivorship was 98% for the stem and 100% for the cup. Focal osteolysis was observed in 6.6% of cups and 29% of stems. Four hips (2.6%) were revised because of aseptic failure of the biologic fixation and three hips (1.95%) for deep infection. As much as 146 stems and 149 cups were evaluated to be stable. Zweymüller-Plus THA resulted in high survivorship and durability at 11 years, although the rate of osteolysis around the stem indicated polyethylene wear.

Cementless total hip replacement: a prospective clinical study of the early functional and radiological outcomes of three different hip stems

Optimal fixation of cementless total hip stems is essential for long-term survival rates. The purpose of this prospective study was to evaluate the early clinical and radiological outcomes of two new total hip stems with metaphyseal (Symax®) and predominantly diaphyseal (Hipstar®) anchoring principles in comparison to the well-established straight Zweymueller (SL-Plus®) stem. Clinical and radiological evaluations of 74 patients were undertaken preoperatively as well as at 6 and 12 months postoperatively using the Harris Hip Score (HHS) and Western Ontario and McMaster Universities-Score. During follow-up no stem had to be revised. The mean preoperative HHS of the three study groups amounted to 54.6 ± 15.7 points. At the 12 months follow-up the mean HHS in the SL-Plus group (n = 22) was 88.3 ± 10.5 points, in the Hipstar group (n = 25) 83.3 ± 15.0 and the in Symax group (n = 27) 83.6 ± 15.1. Due to stress shielding the straight Hipstar stem revealed radiolucent lines in the proximal Gruen zones of about 60%, whereas the SL-Plus stem showed significantly more radiolucent lines (87%). However, subsequent long-term studies must be carried out in order to clarify if the progression of radiolucent lines may influence the clinical result and implant longevity.

Primary total hip arthroplasty with a flattened press-fit acetabular component in osteoarthritis and inflammatory arthritis: a prospective study on 416 hips with 6–10 years follow-up

A flattened cup was designed to create a more physiological load transfer to the pelvic bone compared to hemispherical cups, and to allow more bone contact compared to low-profile' spherical cups. To investigate these theoretical advantages and the potential influence of the quality of the acetabular bone, a clinical study was performed in patients with osteoarthritis (OA) and inflammatory arthritis (IA). The aims of the study were (1) to evaluate the fixation of the cup, postoperatively and later when osseous integration should have taken place, (2) to assess perioperative complications such as acetabular fractures and (3) to monitor the polar gap, a potential risk factor for osteolysis. A prospective study was performed on all consecutive OA and IA patients with an indication for primary total hip arthroplasty (THA). Three hundred and nine OA patients (340 hips) and 65 IA patients (76 hips) were included. The acetabular component was the flattened press-fit EPF-PLUS cup, the femoral component the tapered cementless Zweymueller SL-PLUS stem. All revisions and complications were recorded. Clinical and radiographical evaluation was performed on regular basis during 6-10 years. The incidence of early loosening of the cup was 0 out of 340 in the OA group and 1 out of 76 in the IA group. The incidence of acetabular fractures was 7 out of 340 in the OA group and 3 out of 76 in the IA group. Failure rate for the acetabular component due to aseptic loosening or osteolysis after 6-10 years was 0% in the OA group and 4.8% in the IA group. In all cases available for follow-up the polar gap had disappeared and full osseous integration had taken place in both the groups. This study shows that the flattened press-fit acetabular component creates adequate initial mechanical stability to allow osseous integration and that the cup can be safely used in both OA and IA patients. However, after 6-10 years, in the IA group failure of the cup due to aseptic loosening occurred once and failure due to osteolysis occurred three times, while these type of failures did not occur in the OA group.

Good results with an uncoated grit-blasted tapered straight stem at ten years

In the literature, there is no consensus on the value of uncoated cementless femoral stems. We asked whether the results obtained with a grit-blasted titanium surface would prove the usefulness of this implant at an intermediate follow-up time. Three hundred and sixty five patients (376 hips) underwent primary total hip arthroplasty (THA) using the SL-Plus stem in combination with a ceramic-PE articulation. At a minimum follow-up time of 10.0 years (mean 10.2 years; range, 10.0 to 12.6 years), 229 stems (60.9%) were available for analysis. Five revisions were performed, one because of low-grade infection, one because of an aseptic loosening, another one because of a traumatic subsidence and two because of periprosthetic fractures. The 10-year survivorship with revision for any reason as event of interest was 98.3% (95% CI: 96.0%–99.3%). Radiologically two stems were diagnosed to be loosened at follow-up. Osteolytic lesions were detected in 5 patients. The implant survivorship with revision and radiographic sign of loosening as event of interest was 95.7% (95% CI: 89.0%–98.4%) at the time of maximum follow-up (12.6 years). Radiolucent lines (RLs) occurred in 27.9% mostly in positions 1 and 7. In the age group less than 70 years of age, 35% were found to show RLs, in the age group older than 70 years of age only 12.5% showed RLs. The five patients with osteolytic lesions were all from the age group ≤ 70 years. These intermediate results document that primary implants with a grit-blasted titanium surface ensure an excellent intermediate-term outcome clinically and with regards to the survival rate. It also confirms our approach not to accept any age limits for selecting patients for cementless THAs. A prospective study will have to show whether additional hydroxyapatite (HA)-coating can improve the radiologic outcome.

Minimally invasive total hip replacement via the anterolateral approach in the supine position

Total hip arthroplasty through minimally invasive procedures potentially reduces operative trauma, which is expected to result in improved recovery and rehabilitation. We presently perform total hip arthroplasty using minimally invasive techniques via an anterolateral modification of the Watson-Jones approach. This approach is performed in the supine position and requires sterile draping of both legs. It also involves a modified operative technique which preserves the pelvitrochanteric muscles and extends the release of the hip capsule. In order to employ a proven implant system (BICON-PLUS threaded cup, SL-PLUS stem), it was necessary to modify the stem rasps and use manipulation rasps as trial stems. In this report, we compare 50 conventional total hip replacements with 50 procedures performed using the minimally invasive procedure in terms of blood loss and the duration of the operation. The length of the skin incision varied between 7 and 12 cm with the minimally invasive technique, compared to 15 to 22 cm with the conventional procedure. Both groups were virtually identical with respect to average blood loss (haemoglobin on 10th post-operative day: minimally invasive group, 108.0 g/L; conventional group, 112.0 g/L) and the duration of the procedure (minimally invasive group, 60 minutes; conventional group, 58 minutes). The position of the implanted components correlated with the pre-operative planning with regard to medial head offset, centre of rotation of the hip, and leg length, and was as satisfactory as that observed with the conventional procedure. The complication rate was low (2.9%). Shaft fissures occurred in the first months of use of the minimally invasive procedure before adaptation of the shaft rasps. Dislocations were attributable to improper patient behaviour. Minimally invasive surgery via the anterolateral approach in the supine position was equivalent to the conventional procedure, had a low rate of complications, and did not adversely impact the technical success of the procedure.

METALLOSIS AFTER CONTEMPORARY METAL-ON-METAL TOTAL HIP ARTHROPLASTY

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

Metallosis After Contemporary Metal-on-Metal Total Hip Arthroplasty

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. 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. 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. 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.