BIRMINGHAM HIP RESURFACING ARTHROPLASTY: A SERIES OF 117 CONSECUTIVE HIPS WITH A MINIMUM FIVE-YEAR FOLLOW UP

Abstract

We report 114 of 117 (97% follow up) consecutive metal-on-metal hip resurfacings in 105 patients with a minimum of 5 years follow up implanted between October 1999 and May 2002. Revision of either the femoral or acetabular component during the study period is defined as failure. No other revisions have been performed or are impending. We had 4 failures giving us survivorship at 5 years of 97% (95% confidence interval (CI) 94 – 100). The mean follow up was 72 months and the mean age at implantation was 54.5 years old (Range 35 – 75). All patients were followed up clinically and radiographically.

The mean Harris hip score at follow up was 96.4. The mean Oxford Hip Score fell from 41.6 preoperatively (Range 16 – 57) to 15.3 postoperatively (Range 12 – 49) p< 0.0001. The UCLA Activity Scale rose from 3.93 preoperatively (Range 1 – 10) to 7.54 postoperatively (Range 4 – 10) p< 0.001.

Radiographic analysis revealed an average stem shaft angle of 130.6 degrees (Range 112 – 148) with average cup alignment of 36 degrees (Range 22 – 47). Neck thinning was present in 12 hips (10%) and we define a technique for measuring thinning. Heterotropic ossification was present in 17 hips and lucent lines around the femoral component in 10 hips.

This study confirms that metal-on-metal resurfacing produces an excellent clinical and functional outcome in the younger patient who requires surgical intervention for hip disease. The results compare favourably with those from the originating centre and confirm that resurfacing is well suited for younger higher demand patients. It is the first study with a minimum 5 year follow up from outside the originating centre.