Acetabular component thickness does not affect mid-term clinical results in hip resurfacing.

BACKGROUND: The benefits of using thin acetabular components for hip resurfacing have been shown in terms of bone conservation, but there currently are little data available in the literature addressing the mid-term clinical results of these devices. QUESTIONS/PURPOSES: We aimed to determine whether thinner acetabular components altered mid-term postoperative clinical scores, complication rates, survivorship, radiographic appearance, and metal ion levels. METHODS: Two hundred eighty-one patients with unilateral disease received a 5-mm thick acetabular shell and 223 received a 3.5-mm shell. The femoral component implanted in both groups was identical. We compared clinical scores, complication rates, survivorship, radiographic results, and ion levels between these two groups. RESULTS: UCLA hip scores were similar (pain, p = 0.0976; walking, p = 0.9571; function, p = 0.9316; activity, p = 0.2085). Complications were higher in the 5-mm group (6.4% versus 1.8%, p = 0.0431). Both groups were similar regarding survivorship (p = 0.3181), cup radiolucency at 5 years (p = 0.107), and metal ion levels (cobalt p = 0.404, chromium p = 0.250). CONCLUSIONS: With comparable mid-term clinical results, there is no tangible reason to abstain from using the 3.5-mm acetabular component. LEVEL OF EVIDENCE: Level III, retrospective comparative study. See the Guidelines for Authors for a complete description of levels of evidence.

Wear analysis of 39 conserve plus metal-on-metal hip resurfacing retrievals.

There have been increasing concerns regarding adverse local tissue reactions (ALTR) following metal-on-metal (MOM) hip arthroplasties. This study examined wear rates in retrievals of one design of MOM resurfacing arthroplasty, and assessed the differences in wear between those with and without ALTR. Wear measurements were made on 39 MOM resurfacing components (30 femoral, 9 acetabular) which were at least 2years in vivo. Seven hips (6 patients; 4 acetabular components, 7 femoral components) were identified to have ALTR. Acetabular component abduction and anteversion angles were determined using EBRA, and the contact-patch-to-rim (CPR) distance was calculated. The ALTR group had higher linear femoral and acetabular wear rates, acetabular anteversion and abduction angles, lower CPR, and longer time to revision. Given the increased risk for ALTR associated with acetabular component malpositioning, patients with malpositioned acetabular components may require closer clinical follow-up and monitoring.

Contact patch to rim distance predicts metal ion levels in hip resurfacing.

BACKGROUND: Component design, size, acetabular orientation, patient gender, and activity level have been suggested as factors leading to elevated metal ion concentrations after-on-metal hip resurfacing arthroplasty (MMHRA). The calculation of the contact patch to rim (CPR) distance integrates component size, design, and acetabular orientation and may be a good predictor of elevated metal ion levels. QUESTIONS/PURPOSES: We evaluated the effects and the predictive value of the CPR distance on serum cobalt (CoS) and chromium (CrS) ion levels. METHODS: We retrospectively studied 182 patients with Conserve Plus MMHRAs at a minimum of 12 months after surgery (median, 57 months; range, 12-165 months). CoS and CrS levels were analyzed using inductively-coupled plasma mass spectrometry. Multiple logistic regression was performed to determine which if any of the factors related to serum ion levels. RESULTS: Patients with CPR distances of 10 mm or less had a 37-fold increased risk of having elevated CoS of 7 µg/L or higher. Similarly, these patients had an 11-fold increased risk of having elevated CrS of 7 µg/L or higher. Sex and University of California Los Angeles activity scores did not influence the postoperative CoS and CrS levels. The negative predictive value for CPR distance less than 10 mm was 99.3% for CoS greater than 7 µg/L and 98.0% for CrS greater than 7 µg/L. CONCLUSIONS: Our observations suggest the CPR distance would be a useful indicator to determine which patients are at risk for elevated ion levels. Patients with CPR distances greater than 10 mm need not be monitored unless they become symptomatic.

The insidious risk of periprosthetic fracture in clinically functional total hip arthroplasties: A biomechanical study of willed joints.

Femoral bone quality is a major risk factor of periprosthetic fracture after total hip arthroplasty (THA), which has mortality similar to native hip fractures but higher short-term morbidity. The goal of this study was to quantify cortical strains at the site of expected Vancouver Type-B periprosthetic fracture as a function of bone mineral density, femoral stem material, and fixation method using a series of 29 autopsy-retrieved, clinically asymptomatic hip joints with THA. Periprosthetic bone mineral content and density was assessed using dual-energy X-ray absorptiometry by Gruen Zone. Specimens then underwent combined cyclic axial and torsional loading, increasing incrementally from 100 N and ±1 Nm to peaks of 700 N and ±5 Nm. All specimens experienced significantly higher strains on the lateral surface than on the anterior surface, indicating that the bending loads in the frontal plane, rather than axial/torsional loads, had the predominant effect. Multiple significant relationships (p = 0.04, p = 0.02) were found between predicted periprosthetic strains calculated from radiographic measurements and observed principal strains. Though THA in the present study were in successful clinical service, the produced results indicated that some femurs with rigid cemented or noncemented implants were potentially at high risk for Vancouver Type-B fractures, which may be predicted radiographically.

Nonarthroplasty Options for the Athlete or Active Individual with Shoulder Osteoarthritis.

The management of glenohumeral osteoarthritis is difficult in young, active individuals. After nonoperative management fails, arthroscopic debridement with concomitant procedures (eg, loose body removal, capsular release, labral debridement, synovectomy, osteophyte resection, bursectomy, subacromial decompression, microfracture, and biceps tenotomy or tenodesis) to address potential pain generators may be an option in small, contained, unipolar lesions.

Highly cross-linked polyethylene in hip resurfacing arthroplasty: long-term follow-up.

Highly cross-linked polyethylene (XLPE) has improved wear properties. This study reports the results of a small series of patients treated over 10 years ago with a metal-on-XLPE hip resurfacing.A total of 21 hips in 20 patients received a hip resurfacing with a cobalt-chromium metal femoral head and metal-backed acetabular cup lined with a XLPE insert and were retrospectively studied. Kaplan-Meier Survivorship was calculated.Five patients who had initial extreme cystic disease in the femoral head failed due to femoral loosening. Survivorship was 95.2% at 5 years and 81.0% at 10 years.We found that XLPE wear was not implicated in these failures, which were primarily attributed to poor bone quality of the femoral head, early bone preparation, cementing technique and excessive head reaming to near the neck diameter, necessitated for the implantation of a thick two-part socket.

Do clinical and quality of life scores change over time after hip resurfacing?

BACKGROUND: Metal-on-metal hip resurfacing (MOMHR) is an alternative to total hip replacement in young and active patients but little is known about the evolution of clinical outcome scores of hip resurfacing over time.The purpose of this study was 1) to assess the long-term evolution of UCLA hip scores and SF-12 Quality of life evaluations in a group of patients treated with hip resurfacing arthroplasty, 2) to determine whether the age of the patient at surgery influenced these outcome measurements, and 3) whether the changes in SF-12 scores are comparable with those of the general US population. PATIENT AND METHODS: A total of 100 patients with unilateral, unrevised, Charnley class A MOMHR were retrospectively selected for the study. UCLA and SF-12 scores were calculated preoperatively, short-term postoperatively, and beyond 10 years. RESULTS: There was a decrease in the UCLA function and activity scores, and in the SF-12 physical scores between the short-term and the last follow-up at a minimum of 10 years. However, pain, walking, and SF-12 mental scores were maintained through the last follow-up. Furthermore, the SF-12 physical scores at last follow-up were comparable with those of the general US population while the mental scores were greater. There were no significant differences between the two age groups at any of the follow-up intervals for any outcome measurement. CONCLUSIONS: While there is a slight decline in physical function following hip resurfacing over time, pain relief, walking ability, and quality of life are maintained.

The effect of patient selection and surgical technique on the results of Conserve® Plus hip resurfacing--3.5- to 14-year follow-up.

The results of metal-on-metal hip Conserve® Plus resurfacings with up to 14 years of follow-up with and without risk factors of small component size and/or large femoral defects were compared as performed with either first- or second-generation surgical techniques. There was a 99.7% survivorship at ten years for ideal hips (large components and small defects) and a 95.3% survivorship for hips with risk factors optimized technique has measurably improved durability in patients with risk factors at the 8-year mark. The lessons learned can help offset the observed learning curve of resurfacing.

Incidence and significance of femoral neck narrowing in the first 500 Conserve® Plus series of hip resurfacing cases: a clinical and histologic study.

Narrowing of the femoral neck after metal-on-metal hip resurfacing arthoplasty has been reported as a common radiologic feature, although its significance is still unknown. This study reports the presence and significance of neck narrowing in the first 500 consecutive Conserve® Plus metal-on-metal hip resurfacings in 431 patients.

Mid-to-long term follow-up of Transcend metal-on-metal versus Interseal metal-on-polyethylene bearings in total hip arthroplasty.

Second-generation metal-on-metal total hip arthroplasty (THA) was introduced in the early 1990s to address osteolysis and aseptic loosening resulting from polyethylene wear. We present a comparison between the Transcend metal-on-metal and Interseal metal-on-polyethylene THAs. Thirty-seven hips with Transcend metal bearings and 36 hips with Interseal polyethylene acetabular liners but identical acetabular shells were reviewed to determine clinical performance, radiographic changes, and survivorship. Patients with higher anticipated activity levels were selected to receive the Transcend bearing. Mean follow-up time was 107.0 months for the Transcend group, and 90.4 months for the Interseal group. There were no significant differences between the Transcend and Interseal groups for mode of failure and survivorship, which is notable considering the younger and more active Transcend group. However, the Transcend group showed significantly better clinical scores, which may have been a result of the selection methods. Neither surface was differentially implicated in osteolysis, aseptic loosening, or adverse local tissue reaction (ALTR). Our study shows a favorable and comparable performance for both systems.

Complications after metal-on-metal hip resurfacing arthroplasty.

This article determines the incidence and cause of the complications commonly associated with metal-on-metal hip resurfacing implants and the proposed methods to prevent these complications. The literature available in PubMed was reviewed. Complication rates after hip resurfacing are low, and the procedure has shown both safety and efficacy in the hands of surgeons trained in specialized centers. Proper surgical technique can further reduce the incidence of femoral neck fracture, component loosening, and abnormal wear of the prosthesis. A more systematic detection of adverse local tissue reactions is needed to provide accurate assessments of their prevalence.

Failure modes of 433 metal-on-metal hip implants: how, why, and wear.

Metal-on-metal total hip replacements (THRs) and hip resurfacings are coming under increasing scrutiny in light of concerns that they fail because of high wear and elevated metal ions. The aim of this study was to investigate the modes of failure in a collection of 433 metal-on-metal THRs and hip resurfacings and to examine the correlations between the reasons for revision and a range of patient and implant variables considered relevant to implant wear.