UNICOMPARTMENT OR TOTAL KNEE REPLACEMENT - EVIDENCE BASED PRACTISE OR SURGEON’S PREFERENCE?

Abstract

Introduction: A subjective observation suggests that a significant percentage of patients offered a TKR could benefit from a relatively more conservative, less invasive unicompartmental knee arthroplasty. We set out to challenge this hypothesis.

Materials & Methods: 1147 TKRs were performed between 2002 and 2005 at Ravenscourt Park Hospital. 50 consecutive knee x-rays of patients who underwent a TKR were reviewed by three independent observers. Medial and lateral articular cartilage height, varus angulation, and femero-tibial anteroposterior and mediolateral translation were measured on antero-posterior and lateral weight bearing radiographs. Skyline views were analysed for patellofemoral disease. The most appropriate procedure according to local radiological criteria was recorded for all three observers. Unicompartmental arthroplasty was considered when the following criteria was met 1) anteromedial disease with preservation of posterior slope, 2) preservation of the tibial spines, 3) no anteroposte-rior or mediolateral translation, 4) normal tibiofemoral alignment and 5) preservation of patellofemoral joint. Osteophytes were disregarded. Tricompartmental disease merited a TKR while isolated patellofemoral (PFJ) disease considered for PFJ replacement. Patients were not formally examined. Preoperative Knee Society Scores (KSS) and WOMAC scores were noted.

Results: The three observers indicated that 26 (52%), 21 (42%) and 22 (44%) patients respectively could potentially benefit from a unicompartmental arthroplasty given the right clinical setting. Consensus was reached for unicompartmental replacement in 16 (31.2%) and for TKR in 18 (36%) of cases. There was no correlation between the operation performed and operation proposed (42% ± 8) suggesting that the surgeon’s preference is a dominating factor. Interestingly within the proposed unicompartmental group Knee Society Scores were higher (100 ± 22 vs 71 ± 26) giving an indication to the disease severity.

Conclusion: The clinical benefit and economic value of opting for a unicondylar knee arthroplasty when indicated is considerable. None the less it was only considered by a minority of surgeons who undertake knee arthroplasty.