Clinical and radiological outcome of hydroxyapatite-coated femoral stem in revision hip arthroplasty.

We used a proximally hydroxyapatite-coated femoral stem in revision arthroplasty of 48 cases with aseptic loosening and Paprosky defect class 1 or 2. We reviewed the outcome after 6.1 (4--9.3) years. The clinical outcome was good, with a mean postoperative HHS of 90 (51--100) points. There were five reoperations all on the acetabular side and none for the femoral stem. At follow-up, we observed cancellous sclerosis radiographically in 19 cases-especially in non-tightly fitted stems and mainly in Gruen zones 2 and 6. In 13 cases, cortical thickening was seen, mainly in Gruen zones 3 and 5 and especially in tightly fitted stems. These bony changes were significant and not related to any clinical parameter. They started to appear from 6 months onward, with increasing frequency with longer follow-up. We find that the standard Mallory-Head hydroxyapatite-coated femoral stem is suitable for revision in cases with lower-class femoral defects.