Abstract
Background
There is much research on metal on metal hip resurfacing arthroplasty (HRA) but few studies have reported the outcome with respect to implant characteristics from non-specialist centres.
Aim
To report the survival, clinical and radiological outcomes of a single surgeon series of HRA with an average follow-up of 5 years.
Methods
All consecutive HRAs performed by a single surgeon between 2002–2010 at a district general hospital were examined clinically and radiologically. The median follow-up was 61 months (12–102). Clinical assessment included the Oxford Hip Score (OHS) and University of Los Angeles (UCLA) Activity Score. Radiological assessment included implant position and various bony changes. Survival was defined as a need for revision of either component.
Results
There were 75 HRA procedures (59 patients): 70 Birmingham, 2 Conserve, 2 Adept and 1 ASR. The median age was 58 years (25–75) with 46.7% (35) male and 53.3% (40) female. 4.2% (3) patients were lost to follow-up. The mean acetabular and femoral implant sizes were 54.8mm (48–64) and 48.2mm (42–58) respectively. The mean acetabular and femoral inclination angle was 45.4° (20.8–75.2°) and 138° (133–149.5°) respectively. Survival rate was 92% with 6 revisions due to aseptic loosening (3) and fracture (3). These failures were all predominantly female (5) with significantly smaller mean acetabular (50mm, p=0.036) and femoral (43.3mm, p=0.038) implant sizes. Moreover, they had a higher mean acetabular inclination angle of 47.8° (p=0.27). The mean OHS was 43.5 (25–48) and the mean UCLA activity score was 6.7 (3–10). Radiological findings included heterotopic ossification in 21.6% (16), radiolucent lines in 6.8% (5), femoral neck thinning in 2.7% (2) and notching in 5.4% (4).
Discussion
HRA has been shown to have comparable clinical and radiological short-medium term outcomes in a non-specialist centre using different implants. Failed procedure rate is high and patients were predominantly female, with significantly smaller implants and a higher acetabular inclination angle. Vigilance is therefore required in case selection and in follow-up for such patients.
