Systemic levels of metal ions are surrogate markers of in-vivo wear of metal-on-metal hip resurfacings (MoMHRA). The wear-related generation of metal ions is associated with component size and positioning but also with design specific features such as coverage angle, clearance, metallurgy and surface technology. The objective of the study was to investigate whether a hip resurfacing design (ACCIS) with TiNb engineered bearing surfaces would generate less chromium (Cr) and cobalt (Co) ions during and after the run-in phase of wear and whether Ti ions could be detected indicating wear of the coating.INTRODUCTION
OBJECTIVES
Metal-on-metal hip resurfacings (MoMHRAs) have a characteristic wear pattern initially characterised by a run-in period, followed by a lower-wear steady-state. The use of metal ions as surrogate markers of in-vivo wear is now recommended as a screening tool for the in-vivo performance of MoMHRAs. The aims of this retrospective study were to measure ion levels in MoMHRAs at different stages during the steady-state in order to study the evolution of wear at minimum 10 years postoperatively and describe factors that affect it. A retrospective study was conducted to investigate the minimum 10-year survivorship of a single-surgeon Birmingham Hip Resurfacing (BHR) series, and the evolution of metal ion levels. Implant survival, Harris Hip Scores (HHS), radiographs and serum metal ion levels were assessed. The evolution of metal ion levels was evaluated in 80 patients for whom at least two ion measurements were available at more than 12 months postoperatively, i.e. past the run-in phase. Ion level change (Delta Cr; Delta Co) was defined as Cr or Co level at last assessment minus Cr or Co level at initial assessment. Sub-analysis was performed by gender, diagnosis, age, femoral component size and cup inclination angle.Introduction
Materials and methods
Hip resurfacing (HRA) designer centres have reported survivorships between 88.5–96% at 12 years. Arthroplasty Registries (AR) reported less favourable results especially in females gender and small sizes. The aim of this study was to evaluate the minimum 10-year survival and outcome of the Birmingham Hip Resurfacing (BHR) from an independent specialist centre. Since 1998, 1967 BHRs have been implanted in our centre by a single hip resurfacing specialist. The first 249 BHR, implanted between 1999 and 2001 in 232 patients (17 bilateral) were included in this study. The majority of the patients were male (163; 69%). The mean age at surgery was 50.6 years (range: 17–76), with primary OA as most common indication (201; 81%), followed by avascular necrosis (23; 9.2%) and hip dysplasia (11; 4.4%). Mean follow up was 10.2 years (range: 0.1 (revision) to 13.1). Implant survival was established with revision as the end point. Harris Hip Scores (HHS), radiographs and metal ion levels were assessed in all patients. Sub-analysis was performed by gender, diagnosis and femoral component size (Small: <50 mm; Large: ≥50 mm).Introduction
Methods
