Resurfacing Versus Non-resurfacing the Patella in Total Knee Arthroplasty: An Appraisal of Available Evidences

The decision whether to resurface or not the patella in total knee arthroplasty (TKA) is highly controversial and surgeons show a wide variety of attitudes in Europe and in the USA. Surgeons favouring patellar resurfacing advocate that post-operative knee pain following TKA is significantly diminished, which would improve patient-based outcome. On the other hand, patellar replacement carries a number of potential complications which may outweigh the benefit of reduced anterior knee pain. A systematic search of available evidences comparing the outcome of unresurfaced versus resurfaced patellae in TKA was therefore conducted. The purpose of the present paper is providing orthopaedic surgeons with an updated appraisal of relevant evidences that may assist them in their decisionmaking process. Material and Method: A bibliographic search was conducted through the most representative databases. We searched for meta-analyses (MA), systematic reviews (SR) and randomized controlled trials (RCT) comparing outcome between resurfaced and unresurfaced patellae in TKA. The following databases were used: Cochrane Muskuloskeletal Injuries Group Specialized Register, the Cochrane Register of Controlled Trials, Health Technology Assessment (HTA), PEDro, Medline, EMBASE, CINAHL, AMED, DARE, TRIP, The National Research Register (UK). The search was ended on February 2008. The search term selected from The National Library of Medicine’s medical subject heading (MESH) database were: patella; resurfacing; total knee arthroplasty; TKA; total knee replacement; TKR. Additionally, the rate of reduced post-operative anterior knee pain in patients undergoing patellar resurfacing was compared with the current rate of complications associated with patellar replacement. Results: Five MAs, 1 SR and 6 RCTs not included in the published evidence syntheses were retrieved. All evidence syntheses would warrant patellar resurfacing in order to reduce anterior knee pain and the related risk of re-operation. Conversely, 4 RCTs failed to detect significant differences using accepted clinical scores at mid- and long-term follow-up while 2 RCTs did not report significant variations of the biomechanical performance in vivo between replaced and un-replaced patellae. Conclusion: Current evidences would support the decision to resurface the patella when anterior knee pain and the related risk of re-operation are used as end-points of outcome at mid-term follow-up. However, no clinical differences would be detectable between resurfaced and unresurfaced patellae at long-term follow-up. In addition, both patella-replaced and patella-unreplaced TKA exhibit similar biomechanical behaviour in vivo. The rate of anterior knee pain improvement in patients undergoing patellar replacement should be contrasted with the rate of potential complications related to patellar resurfacing.