Fixation and Wear With Contemporary Acetabular Components and Cross-Linked Polyethylene at 10-Years in Patients Aged 50 and Under

Ten Year Outcomes of Contemporary Total Hip Arthroplasty in Adolescent and Young Adult Patients are Favorable

BACKGROUND

The purpose of this study was to assess 10-year patient-reported outcome measures, complications, polyethylene wear-rates, and implant survivorships in patients ≤30 years of age treated with contemporary total hip arthroplasty (THA).

METHODS

We retrospectively assessed 121 patients (144 hips) who underwent THA at age ≤30 years (mean 23 [range, 11 to 30]) at an average follow-up duration of 10.7 years (range, 8 to 17). Highly-crosslinked polyethylene acetabular liners were used in all cases. Femoral heads were ceramic (74%) or cobalt-chrome (26%). There were 52 hips (36%) that had previous surgery and 31 hips (22%) were in patients who had associated major systemic comorbidities. We analyzed the modified Harris Hip scores, University of California Los Angeles Activity Scores, major complications, polyethylene wear-rates, and implant survivorships.

RESULTS

At final follow-up, the average modified Harris Hip scores improved from 47 (±15.1) to 81 (±19.5) with an average 34-point improvement. The University of California Los Angeles scores improved from 4.0 (±2.3) to 6.0 (±2.4). The major complication rate was 5.6%. There were 6 hips (4.2%) that were revised. Indications for revision included instability (3, 2.1%), late infection (1, 0.7%), liner dissociation (1, 0.7%), and acetabular loosening (1, 0.7%). Mean linear (0.0438 mm/y) and volumetric (29.07 mm3/y) wear rates were low. No periprosthetic osteolysis was detected in any hip. Survivorship free from revision for any reason was 97.2, 95.8, and 95.8% at 5, 10, and 15 years.

CONCLUSIONS

Contemporary THA in patients ≤30 years of age is associated with marked clinical improvements at 10-year follow-up and encouraging survivorship estimates at 15 years.

Contemporary Porous Titanium Acetabular Components for Total Hip Arthroplasty After Pelvic Radiation

BACKGROUND

Patients undergoing primary total hip arthroplasty (THA) following pelvic radiation have historically had poor survivorship free of aseptic acetabular component loosening. However, several series have reported improved results with tantalum acetabular components. The purpose of this study is to assess implant survivorship, radiographic results, and clinical outcomes of contemporary, porous titanium acetabular components in the setting of prior pelvic radiation.

METHODS

We retrospectively reviewed 33 patients (38 hips) with prior pelvic radiation between 2006 and 2016 who underwent primary THA. The mean overall pelvic radiation dose was 6300 cGy with a mean latency period to THA of 5 years. The most common acetabular component was Pinnacle (DePuy Synthes) in 76%. Eight-seven percent of cups were fixed with screws. The mean age at primary THA was 74 years, 76% were male, and the mean body mass index was 30 kg/m². Mean follow-up was 5 years.

RESULTS

The 10-year survivorship free of revision for aseptic loosening, free of any revision, and free of any reoperation were 100%, 89%, and 89%, respectively, when accounting for death as a competing risk. There were 3 revisions; one each for taper corrosion, recurrent dislocation, and infection. Radiographically, all cups had evidence of osteointegration and none had radiographic evidence of loosening. The mean Harris Hip Score improved from 50 to 84 postoperatively (P < .0001).

CONCLUSION

Contemporary porous titanium acetabular components with supplemental screws provided excellent implant fixation in patients with prior therapeutic pelvic radiation. At 10 years, 100% of these components were free of revision for aseptic loosening and 100% were radiographically well-fixed.

LEVEL OF EVIDENCE

Level IV, Therapeutic.

Incidence of Osteolysis and Aseptic Loosening Following Metal-on-Highly Cross-Linked Polyethylene Hip Arthroplasty: A Systematic Review of Studies with Up to 15-Year Follow-up

BACKGROUND

This study compared the incidence of osteolysis, aseptic loosening, and revision following use of highly cross-linked polyethylene (HXLPE) or conventional polyethylene (CPE) at medium to long-term (>5 to 15 years) follow-up in primary total hip arthroplasty (THA). Incidences were quantified and compared with regard to age and method of implant fixation.

METHODS

Using the PRISMA (Preferred Reporting Items for Systematic reviews and Meta-Analyses) guidelines, 12 randomized controlled trials and 18 cohort studies were investigated for evidence-based outcomes following HXPLE and CPE use in 2,539 hips over a 5 to 15-year follow-up.

RESULTS

Lower rates of osteolysis, aseptic loosening, and implant revision were reported following use of HXLPE liners. Osteolysis was reduced from 25.4% with CPE to 4.05% with HXLPE in young patients, and from 29.7% to 6.6% in the older patient cohort. Similarities in osteolysis rates were observed when cemented (24.9% for CPE and 6.5% for HXLPE) and uncemented components (32.8% for CPE and 7.1% for HXLPE) were compared. No clear advantage in the type of HXLPE used was observed.

CONCLUSIONS

Over a follow-up period of up to 15 years, when compared with CPE, use of HXLPE liners reduced the incidence of osteolysis, aseptic loosening, and implant revision, regardless of the fixation method and including in younger and potentially more active patients.

LEVEL OF EVIDENCE

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

Third-Generation Medium Cross-Linked Polyethylene Demonstrates Very Low Wear in Total Hip Arthroplasty

Background

Cross-linked polyethylene (XLPE) liners have shown lower wear rates than conventional polyethylene liners in total hip arthroplasty. The primary aim of our study was to report our most recent analysis of wear rates and clinical outcomes of a third-generation XLPE liner. Secondary aims were to investigate the rate of adverse events related to mechanical failure or oxidation of this liner.

Methods

A series of 266 total hip arthroplasties using a specific XLPE liner were retrospectively reviewed. Radiographs were examined to determine linear and volumetric wear rates and presence of osteolysis. Clinical outcomes, revision rates, mechanical failures, and risk factors for accelerated polyethylene wear were additionally investigated.

Results

The mean age at the time of surgery was 65.8 years and the mean follow-up was 5.5 years. The mean linear wear rate was 0.003 mm/year and the mean volumetric wear rate was 0.42 mm³/year, and there was no evidence of osteolysis. Harris hip scores increased from 50.9 preoperatively to 96.0 at the latest follow-up. The revision rate was 0.4%, with no liner rim fractures and no liner dissociations/loosenings. Femoral head material, head size, age, body mass index, and time since implantation had no effect on wear rates.

Conclusion

Wear rates for this third-generation XLPE liner were low at mid-term follow-up, and no adverse sequelae of oxidation or deleterious mechanical properties were observed. This remained true regardless of femoral head size and material or patient age and body mass index. Further analysis will be necessary to ensure continued wear resistance, oxidative stability, and mechanical strength at long-term follow-up.

Radiographic and Clinical Outcomes of Modular Tapered Fluted Stems for Femoral Revision for Paprosky III and IV Femoral Defects or Vancouver B2 and B3 Femoral Fractures

BACKGROUND

Extensive femoral bone loss poses a challenge in revision total hip arthroplasty (rTHA). Many techniques have been developed to address this problem including fully porous cylindrical stems, impaction bone grafting, and cementation of long stems, which have had varied success. Modular tapered fluted femoral stems (MTFS) show favorable results. We sought to determine the minimum 2-year radiographic and clinical performance of MTFS in rTHA in a population with extensive proximal femoral bone loss.

METHODS

Our clinical database was queried retrospectively for all patients who underwent rTHA with an MTFS. We included patients with Paprosky 3 and 4 femoral bone loss and patients with Vancouver B2 and B3 periprosthetic femur fractures. Patients without 2-year follow-up were invited to return to clinic for X-ray evaluation and to complete clinical questionnaires. We assessed distance of stem subsidence and presence of stem fixation on final X-ray. We recorded all-cause revision and survival of the stem at final follow-up.

RESULTS

One hundred twenty-nine patients were available for follow-up. Average follow-up time was 3.75 years. One hundred twenty-two stems (95%) remained in place at final follow-up. Median subsidence was 1.4 mm (range 0-21). All-cause revision rate was 16.3% (21 patients). Of the hips revised, 10 were for instability, 6 for infection, 1 for aseptic loosening, and 1 for periprosthetic femur fracture. Three were revised for other reasons. The stem was revised in 7 patients (5.4%), and the most common reason for stem revision was infection (5 patients). The other 2 stems were revised for aseptic loosening in a Paprosky 4 femur and periprosthetic femur fracture. Survival of tapered modular fluted stems with aseptic failure as an endpoint was 98.4%. The mean Hip disability and Osteoarthritis Outcome Score, Joint Replacement score at final follow-up was 73, and mean Veterans Rand 12 item health survey physical and mental scores were 32.8 and 52.2, respectively.

CONCLUSION

In patients with Paprosky 3, 4 femoral defects or Vancouver type B2, B3 fractures, modular tapered fluted stems for femoral revision show excellent outcomes at minimum 2-year follow-up.

Primary Total Hip Arthroplasty in Patients 20 Years Old and Younger

BACKGROUND

Historically, total hip arthroplasty (THA) performed in patients ≤20 years old has been associated with poor survivorship because of bearing-surface wear with conventional polyethylene, acetabular loosening with cemented sockets, and liner fracture in ceramic-on-ceramic (CoC) THA. For this population, there is a paucity of data regarding outcomes of THAs performed with use of modern implants and bearing surfaces. The purpose of the present study was to examine the mid- to long-term outcomes of modern THA in patients ≤20 years old.

METHODS

Utilizing a single-institution, prospectively collected total joint registry, we retrospectively identified 91 primary THAs performed in 78 patients ≤20 years old from 1998 to 2016. The average patient age was 17 years (range, 11 to 20 years), and the average body mass index was 26 kg/m (range, 16 to 49 kg/m). Forty-eight THAs (53%) were performed in male patients, and 47 (52%) were performed on the right hip. Bearing surfaces included CoC (53 THAs, 58%), metal-on-highly cross-linked polyethylene (MoP; 28 THAs, 31%), and ceramic-on-highly cross-linked polyethylene (CoP; 10 THAs, 11%). Outcome measures included reoperations, revisions, complications, clinical outcome scores, and bearing-surface wear.

RESULTS

At an average follow-up of 8 years (range, 2 to 18 years), the average modified Harris hip score was 92 (range, 54 to 100), and 95% of patients reported feeling "much better" following the surgical procedure. Survivorship at 2, 5, and 10 years postoperatively was 96.7%, 96.7%, and 95.0% for reoperation; 98.9%, 98.9%, and 97.2% for revision; and 91.2%, 91.2%, and 89.5% for complications, respectively. The most common complications were instability (3 THAs, 3%), aseptic acetabular loosening (2 THAs, 2%), and postoperative foot drop (2 THAs, 2%). Linear articular wear averaged 0.019 mm/yr. There were no correlations between age, sex, body mass index, bearing surface, femoral head size, use of cement, or operative time and survivorship from complications, reoperations, or revisions. There were no differences in linear wear among CoC, CoP, and MoP bearing surfaces.

CONCLUSIONS

In patients ≤20 years old, THAs performed with use of modern implants exhibit excellent clinical outcome scores and survivorship at mid- to long-term follow-up. CoC, CoP, and MoP bearing surfaces have similar survivorship, clinical outcomes, and bearing-surface wear in this population.

LEVEL OF EVIDENCE

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

Causes of Revision in Young Patients Undergoing Total Hip Arthroplasty

BACKGROUND

The purpose of this study was to identify reasons for revision of total hip arthroplasty (THA) in patients who underwent primary THA at or before the age of 35 years. We hypothesized that the reasons for revision in younger patients would be different from the general older population of patients undergoing THA because of the differences in diagnoses, complexity of deformities, and differences in activity level.

METHODS

Data for 108 hips in 82 patients who underwent primary THA at our institution before the age of 35 years from 1982-2007 and subsequently underwent revision THA were reviewed. Operative reports and clinic notes were reviewed to determine baseline characteristics, reason for revision, timing of revision, and components revised.

RESULTS

The mean age at index surgery was 25.4 years, and mean time from index to revision surgery was 10.1 years. The most common preoperative diagnoses included avascular necrosis, juvenile idiopathic arthritis, developmental dysplasia of the hip, and posttraumatic arthritis. The most common reasons for revision were acetabular loosening (30.1%), femoral loosening (23.7%), and polyethylene wear (24.7%). 8.3% of patients underwent primary THA with highly cross-linked polyethylene, while the remainder of the patients underwent THA when conventional polyethylene was used. There was no statistically significant association between which component(s) were revised and initial fixation (ie cemented or uncemented prosthesis) (P = .26).

CONCLUSION

Causes of revision in this population appear to differ from the general THA population. In young patients, acetabular loosening, femur loosening, and polyethylene wear were the most common causes of revision. Instability and infection were less common compared with literature reports of causes of revision in older patients. Findings in this study may be useful in counseling young patients undergoing THA, though results were likely influenced by the use of conventional rather than highly cross-linked polyethylene in this cohort.

Total hip arthroplasty following failure of tantalum rod implantation for osteonecrosis of the femoral head with 5- to 10-year follow-up

BACKGROUND

Total hip arthroplasty (THA) with failure of tantalum rod implant for osteonecrosis of the femoral head (ONFH) will be the only choice for patients. However,it remains unknown whether tantalum rod implantation has an adverse effect on the survival time of implants following conversion to THA. The aim of this study was to retrospectively evaluate the clinical and radiographic outcomes of conversion to THA in patients who were previously treated with implantation of a tantalum rod.

METHODS

This study included 31 patients (39 hips), who underwent conversion to THA due to failure of core decompression with an implanted tantalum rod. Among these 31 patients, 26 patients were male and five patients were female. The mean age of these patients was 49.3 years old (range: 36-64 years old). The control group included 33 patients (40 hips), who underwent total hip replacement without tantalum rod implantation. The hip Harris score, implant wear, osteolysis, radiolucencies and surgical complications were recorded during the follow-up. The distribution of tantalum debris in the proximal, middle and distal periprosthetic femoral regions, radiolucent lines and osteolysis were analyzed on post-operative radiographs.

RESULTS

There were no significant differences in Harris score, liner wear and complications between the two groups (P > 0.05). Osteolysis and radiolucent lines more likely occurred in patients with tantalum debris distributed in three regions than in one or two regions (P < 0.05).

CONCLUSIONS

The mid-term clinical outcome of patients who underwent THA with tantalum rod implantation was not different from those without a tantalum rod, suggesting that tantalum debris did not increase the liner wear rate. However, the distribution of periprosthetic tantalum debris in the proximal, middle and distal femoral regions may increase the risk of femoral osteolysis and radiolucent lines.

Systematic review: lack of evidence for the success of revision arthroplasty outcome in younger patients

INTRODUCTION

Total hip arthroplasties (THAs) in younger patients are becoming increasingly popular. However, the outcome of subsequent revisions in younger patients is not well known and, therefore, their success (subsequent revision prosthesis survival) might be overestimated. We investigated available data on the outcome of primary- and subsequent revision THAs performed in the same cohort of patients who underwent primary THA under the age of 50.

METHODS

Medline, Embase and the Cochrane Library (CENTRAL) were searched up until April 13, 2016 for studies that reported both the survival of primary and subsequent revisions THA of single cohorts of patients younger than 50. Eligible articles had to include Kaplan Meier analysis or competing risk analysis for survival of the primary THA at a mean follow-up of 10 years, as well as for the subsequent revision THA within the same cohort.

RESULTS

We found 4,799 unique records; 43 of which were potentially eligible. Only 1 paper met our inclusion criteria. It reported on the survival of 69 primary prostheses at a mean of more than 10 years follow-up and 13 subsequent revisions.

CONCLUSIONS

There is a clear lack of evidence about the outcomes of the revision arthroplasty in younger patients. Only 1 study reported the survival-rate of subsequent revision arthroplasty with the minimum 10-year survival rate of the original THA cohort. In the future, this serious lack of knowledge could result in a large number of patients with no further reconstructive options after failed THA, and a large medical burden for society.

Bearing Surfaces for Total Hip Arthroplasty

Metal-on-highly cross-linked polyethylene is considered the preferred bearing surface for conventional total hip arthroplasty because of its safety profile and excellent results in the first 10 to 15 years of use. However, with younger patient age, activity expectations increase, and the life expectancy of patients with total hip arthroplasty also has increased, so interest remains in other bearing couples. These other options include the use of various ceramic composites for the femoral head on highly cross-linked polyethylene, the so-called second-generation antioxidant polyethylenes, and ceramic acetabular liners. Several of these bearing couples have shown excellent wear rates in vitro, and short-term clinical studies have demonstrated favorable wear and safety results. It is uncertain whether any of these bearing couples should be adopted at present. Understanding the unique properties and possible complications of these bearing couples is critical for appropriate implant selection.

Highly Cross-Linked Polyethylene Reduces Osteolysis Incidence and Wear-Related Reoperation Rate in Cementless Total Hip Arthroplasty Compared With Conventional Polyethylene at a Mean 12-Year Follow-Up

BACKGROUND

A number of studies on total hip arthroplasty have compared highly cross-linked polyethylene (HXLPE) with conventional polyethylene (CPE) liners beyond 10 years. However, the impact of HXLPE on the wear-related reoperation rate is unclear. The purpose of this study was to evaluate the clinical advantage of using a single manufacturer's HXLPE in terms of reducing the reoperation rate.

METHODS

The study was a follow-up retrospective cohort study over a mean of 12 years that examined patients aged 45-70 years with cementless total hip arthroplasty using a 26-mm-diameter cobalt-chromium head. Sixty-seven patients (79 hips; HXLPE group = 41 hips, CPE group = 38 hips) were evaluated for a minimum 10-year follow-up. Kaplan-Meier survival analysis was performed, with wear-related reoperations and radiographic osteolysis serving as the end points. The polyethylene wear rate was also assessed.

RESULTS

The mean 12-year follow-up rates of survivorship that were evaluated using wear-related reoperations as the end point were 100% and 91.4% in the HXLPE and CPE groups, respectively (P = .007), and the mean 12-year follow-up rates of survivorship with osteolysis as the end point were 100% and 36.2%, respectively (P < .001). Compared with the CPE group, the HXLPE group presented a significantly reduced wear rate (HXLPE group, 0.035 mm/y; CPE group, 0.118 mm/y).

CONCLUSION

A unique strength of this study is that we assessed a single manufacturer's HXLPE while keeping most other implant parameters uniform. This study reveals the clinical advantage of using a single manufacturer's HXLPE in terms of a reduced wear-related reoperation rate at a mean 12-year follow-up.

Are Trends in Total Hip Arthroplasty Bearing Surface Continuing to Change? 2007-2015 Usage in a Large Database Cohort

BACKGROUND

Bearing surface issues related to trunnionosis or metal-on-metal (MoM) articulations have likely impacted recent trends in bearing surface choice. The purpose of this study is to evaluate trends in total hip arthroplasty (THA) bearing surface use, including 2015 data, with respect to the date of operation and patient demographics.

METHODS

The Humana dataset was reviewed from 2007 through 2015 to analyze bearing surface usage in primary THA. Four bearing surface types were identified by International Classification of Disease, 10th Revision codes and trended throughout the years: metal-on-polyethylene (MoP), ceramic-on-ceramic (CoC), ceramic-on-polyethylene (CoP), and MoM. Prevalence was analyzed as a function of age and sex.

RESULTS

Of the 28,504 primary THA procedures, the most commonly used bearing was MoP (46.1%), followed by CoP (33.2%), MoM (17.1%), and ceramic-on-ceramic (3.6%). The use of CoP bearings significantly increased from 6.4% in 2007 to 52.0% in 2015, while MoM bearings decreased during this period. MoP bearings decreased over 2012-2015 (P < .001). CoP usage decreased with age, while MoP bearings increased with a transition occurring at 65-69 years of age. Women were more likely to receive MoP bearings (odds ratio [OR] 1.2), while men were more likely to receive MoM and CoP bearings (OR 1.1). Multivariate logistic regression showed age to be an independent predictor of bearing surface choice with patients 65 and older more likely to receive MoP bearings (OR 3.2).

CONCLUSION

Bearing surface choice in primary THA has changed tremendously from 2007 to 2015. MoM bearing use has decreased as a result of adverse effects. Age continues to remain a significant factor in bearing surface choice.

Highly Cross-Linked Polyethylene Reduces Wear and Revision Rates in Total Hip Arthroplasty: A 10-Year Double-Blinded Randomized Controlled Trial

BACKGROUND

Highly cross-linked polyethylene (XLPE) was developed to address the problem of wear and osteolysis associated with metal-on-conventional ultra-high molecular weight polyethylene (UHMWPE) bearing surfaces. The purpose of this study was to compare in vivo wear rates and clinical and radiographic outcomes between XLPE and UHMWPE in a prospective double-blinded randomized controlled trial with a minimum of 10 years of follow-up.

METHODS

We randomized 122 patients to receive either a conventional UHMWPE liner (Enduron; DePuy) or an XLPE liner (Marathon; DePuy). Ninety-one patients were assessed clinically and radiographically at a minimum of 10 years (range, 10.08 to 12.17 years). Oxford Hip Scores and Short Form-12 Health Survey scores were collected. The radiographs were analyzed for osteolysis and for 2-dimensional (2-D), 3-dimensional (3-D), and volumetric wear using validated software.

RESULTS

All 122 patients were accounted for at the 10-year follow-up evaluation. Twelve patients had undergone revision surgery, 21 patients had died (1 of whom had previously undergone revision surgery), and 2 patients were unable to return for follow-up, leaving 91 patients available for clinical and radiographic evaluation. At a minimum of 10 years, 3-D wear rates were significantly lower (p < 0.001) in the XLPE group (mean, 0.03 mm/yr) than in the conventional UHMWPE group (mean, 0.27 mm/yr). The prevalence of osteolysis was also significantly lower in the XLPE group (38% versus 8%, p < 0.005), as was the revision rate (14.6% versus 1.9%, p = 0.012), with 10 of the 12 revisions being in the Enduron group. There was no significant difference between the clinical scores of the 2 groups.

CONCLUSIONS

XLPE liners have significantly reduced wear and are associated with a greater implant survival rate at 10 years compared with conventional UHMWPE liners.

LEVEL OF EVIDENCE

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

Survivorship of a modular acetabular cup system: medium- to long-term follow-up

Background

Total hip arthroplasty (THA) requires components that meet a variety of patient factors and needs. This investigation evaluated survivorship of the PINNACLE Acetabular Cup System in primary total hip arthroplasty at 5-10 years.

Methods

In total, 1592 hips (1473 subjects) were enrolled in a multi-center, non-comparative, open-label study of the PINNACLE system: N = 896 metal-on-polyethylene (MOP), N = 667 metal-on-metal (MOM), N = 27 ceramic-on-polyethylene, and N = 2 unknown articulation. Harris Hip Score, Short Form 36, Western Ontario and McMaster Universities Osteoarthritis Index, and radiographs were collected through 10 years. Kaplan-Meier device survivorship was estimated.

Results

There were 41 revisions (23 MOP, 17 MOM, 1 ceramic-on-polyethylene) through 10 years: 56.5% of MOP revisions were for instability and 41.2% of MOM revisions were for adverse local tissue reaction. Kaplan-Meier device survivorship (N with further follow-up) was 97.0% (N = 720) at 5 years and 94.7% (N = 77) at 10 years.

Conclusions

Medium- to long-term survivorship estimates were similar or better than other studies and registries for the PINNACLE system.

Level of Evidence

III.

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 Total Hip Arthroplasty at Five to Twelve Years Follow-Up: A Concise Follow-Up of a Previous Report

BACKGROUND

Concern has arisen regarding potential complications with modular metal-on-metal (MoM) acetabular components in total hip arthroplasty. The purpose of this study was to analyze longitudinally the longer term results of a previously reported cohort of patients utilizing a cementless modular acetabular component with a MoM bearing.

METHODS

One hundred sixty-nine consecutive but selected total hip arthroplasties were performed in 148 patients at 2 institutions using a modular acetabular MoM component. One hundred thirty-nine patients (158 hips) were living at minimum 5 years, 1 patient (1 hip) was lost to follow-up and 8 patients (10 hips) were deceased. Patients were evaluated clinically in terms of revision as well as radiographically. Additional testing (metal ion levels, advanced imaging) was performed when concerns for adverse local tissue reaction (ALTR) arose.

RESULTS

There were 6 (3.8%) additional hips revised since the prior report for a total of 7 hips (4.4%) revised at 5-12 year follow-up. All newly revised hips (3.8%) demonstrated ALTR. There were 7 (4.7%) additional cases of radiographically detected acetabular osteolysis and 7 (4.7%) cases of femoral osteolysis.

CONCLUSION

Longitudinal evaluation of a modular MoM bearing surface acetabular component demonstrated increased rates of ALTR and osteolysis at longer duration follow-up. Although greater than 95% of hips in this study performed well at 5-12 years, when comparing the results to metal-on-polyethylene bearings using the same acetabular component, the results were inferior. Longitudinal surveillance is warranted with this design and this bearing surface couple as cases of ALTR and osteolysis increased with longer follow-up.