Abstract
Aim: To examine the effect that a modular, uncemented, fully coated titanium stem (PFM-R, Protek) has on the bone stock of revised femora.
Methods: Forty revision hip arthroplasties between 1997–2000 were performed by one surgeon using the PFM-R revision stem. The patients were assessed radiographically over a two-year follow-up period. The pre-operative radiographs were examined for bone defects according to Paprosky et al., 1987. Serial radiographs taken post-operatively after two days, six weeks, three months, six months, 12 months and 24 months were used to assess signs of fixation, stability and change in the cortices of 16 femoral zones according to criteria set out by Engh et al., 1987. The change in the density of the bone defects identified at the time of surgery was also examined.
Results: The average age of the patients was 65 years. Thirteen revision stems were followed for one year and 13 were followed for two years. Fourteen patients had an incomplete radiographic follow-up. Two type I defects, 23 type II defects and one type III defect were identified. Twenty-one of the 23 type II defects showed evidence of regeneration in the subtrochanteric metaphysis. One revision stem had radiographic evidence of bone resorption proximally though three stems subsided. No stress shielding was seen distally.
Conclusion: At early follow-up the PFM-R appears to be a viable revision femoral implant which facilitates the regeneration of metaphyseal bone stock.
The abstracts were prepared by Professor A. J. Thurston. Correspondence should be addressed to him at the Department of Surgery, Wellington School of Medicine, PO Box 7343, Wellington South, New Zealand
