Abstract
Introduction: Good intermediate term results have been reported using a hybrid primary total hip arthroplasty (uncemented acetabular component with cemented stem) for osteoarthritis. Concerns have been highlighted recently regarding osteolysis behind the acetabular component. We present our results using the uncemented Aesculap plasma cup with an Exeter cemented femoral stem.
Methods: Outcome of 142 primary hip replacements (124 patients) at Derby Royal Infirmary between 1992–1998 was assessed. Most cases had a 28mm articulation, either Orthinox or ceramic. There were 60 men and 64 women, of mean age 55 (range 33–71). Mean time to follow up was 8.65 years (Range 7–13 years). Radiographic assessment was made to assess wear, acetabular lysis and loosening of the components. A clinical assessment and case note review was also performed.
Results: Of 142 hips, 2 were lost to follow up and 4 patients (6 hips) had died (unrelated causes). Of these, 7 revisions were performed; 3 for osteolysis, and 1 each for infection, acetabular wear, recurrent dislocation and early cup aseptic loosening. 9 hips were identified to have asymptomatic osteolysis (6 acetabular and 2 femoral). Mean rate of linear wear was 0.2mm/year for all hips, but 0.4mm/year for those with osteolysis. No cups without supplementary screw fixation developed acetabular osteolysis.
Conclusions: Our data suggests that there is a significant rate of acetabular osteolysis at intermediate (10 year) follow up of this combination of primary hybrid total hip replacement, often in association with increased acetabular wear. This can be asymptomatic and may lead to the need for complex revision surgery in the future. The failure rate is however significantly lower than in other reported studies with the same basic implants, but differing bearing diameters. This study highlights the need for close radiographic follow up of these patients, and the issue of subtle differences in the articulating surface.
Correspondence should be addressed to The Secretary, BHS, c/o BOA, The Royal College of Surgeons, 35–43 Lincoln’s Inn Fields, London WC2A 3PE.
