Abstract
Background: We have noted a concerning number of early failures (as defined by revision) for Preservation medial mobile-bearing uni-compartmental knee replacements (UKR’s) implanted in our hospital. This study retrospectively reviewed the postoperative radiographs to see if these were as a result of surgical technical failure.
Methods: Between 2003 and 2004, 43 medial mobile-bearing Preservation UKR’s were implanted into 39 patients. The average age of the patients at the time of the index procedure was 61.4 years (range, 46–85), (20 males). The immediate post-operative radiographs were reviewed by 2 independent orthopaedic consultants and a registrar, who were blinded to the patient outcomes, using the radiographic criteria used for the Oxford UKR. We however, particularly tried to identify any medio-lateral offset between femoral and tibial components due to the constrained nature of the prosthesis. A compound error score for all other technical errors was also calculated for each patient.
Results: Six (13.9%) of 43 knees were revised (5 for persistent pain, 1 for tibial component subsidence). Technical errors were few and no correlation was found between post-operative radiographic appearances and the subsequent need for revision. The mean compound error score (maximum value 18) was 4.5 (range, 2–9) in the revision cases and in the non revised cases 3.2 (range, 0–8).
Conclusions: We believe this study gives credence to the opinion that the DePuy Preservation mobile-bearing implant has design faults and is over-constrained leading to early failures in some cases.
Correspondence should be addressed to: Tim Wilton, BASK, c/o BOA, The Royal College of Surgeons, 35–43 Lincoln’s Inn Fields, London WC2A 3PE.
