Abstract
We reviewed 81 consecutive ABG primary total hip replacements in 72 patients operated between January 1993 to December 1998. The mean follow-up was 8.2 years (7 to 12 years). The mean age of the patients was 52 years (range: 28 to 65 years). The mean pre-operative Harris hip score of 42 (range: 24 to 48) improved to a post-operative 80 (range: 58 to 86). At the latest follow-up 2 patients had died through causes not related to surgery. 3 cups had been revised for aseptic loosening. However, 69 of the remaining 75 acetabular cups showed excessive superolateral wear of polyethylene liner. The wear was most pronounced in cups size 46 with a 28 mm head. 16 of the acetabular cups showed significant osteolysis in zone I and II of the acetabulum (Gruen) and are awaiting a revision. None of the stems has been revised to date.
The cumulative survival of prosthesis is as follows:
Stem survival with revision being the end point: 100%
Acetabular cups with revision & aseptic loosening: 72% (95% CI: 61 to 78%)
Acetabular liner with significant wear: 32% (95% CI: 28 to 52%)
The failure of cups is related to the poor locking mechanism of the polyethylene liner. In spite of significant radiological failures of the cups most patients continued to have good Harris hip scores and remained fairly asymptomatic. The results of ABG stem in this series are good but in view of the cup failures we now no longer use the ABG I cups but advocate a long term regular follow-up of these hips
