Abstract
Introduction: Conversion of failed femoral components of total hip resurfacing to conventional hip replacement is reportedly a straightforward procedure. There is little published to qualify this and what is available suffers from small study numbers and various combinations pre and post-operative implants.
Method: Between 1997 and 2002, the Oswestry Outcome Centre prospectively collected data on 5000 Birmingham Hip Resurfacings (BHRs) performed by 141 surgeons, at 87 hospitals. To date 4526 have survived, 135 died and 165 are lost to follow-up.
174 have been revised, of which 60 were failures of the femoral component.
We reviewed modes of failure and post-revision clinical outcomes in this sub-group.
Results: Isolated femoral component failure accounted for 60 hips (1.2%). 28 femoral neck fractures, 14 femoral head collapses, 13 femoral component loosenings, 3 avascular necroses (AVN), 1 femoral loosening followed by fracture and 1 dislocation. Mean time to revision surgery was 2.6years (1.8years for neck fracture; 3.4years femoral loosening, head collapse and AVN).
All acetabular components were left in situ. At revision surgery 25 cemented, 25 uncemented and 10 unknown femoral prostheses were used with 56 BHR modular heads, 2 custom-made Exeter heads and 2 Thrust Plate heads.
47 patients completed outcome scores post-revision surgery. Median modified Harris Hip Score was 82 (IQ range=63–93) and Merle d’Aubigne score was 14 (IQ= 9.5–15) at a mean follow up of 3.9years post-revision.
The 4526 surviving resurfacings had a median hip score of 96 (IQ=87–100) p≥4.558x10-8 and median Merle score of 17 (IQ=14–18) p≥1.827x10-7. Mean 7.0 years follow up.
There was no difference in outcomes between cemented and uncemented revision components nor were there differences between fractured neck of femur and femoral loosening, head collapse or AVN.
Discussion: Following revision of the femoral component to a conventional hip replacement, function is significantly worse than surviving resurfacings.
Correspondence should be addressed to BHS c/o BOA, at the Royal College of Surgeons, 35–43 Lincoln’s Inn Fields, London, WC2A 3PE, England.
