Do we need to restore patellar thickness after total knee arthroplasty with patellar resurfacing?

Purpose The aim of this study was to investigate whether increased patellar thickness after resurfacing decreased knee flexion angle and had any effect on functional outcomes comparing with patellar thickness restoration (patelloplasty) in patients undergoing primary total knee arthroplasty (TKA) or not. Methods We retrospectively reviewed 220 patients undergoing primary TKA: 110 patients undergoing patelloplasty and 110 patients received overstuffed patellar resurfacing using subchondral bone cut at lateral facet technique were recruited. The mean increase in patellar thickness after resurfacing equal to 2 ± 1.2 mm. The outcomes were postoperative knee flexion angle and modified Western Ontario and McMaster University Osteoarthritis Index (WOMAC) score at minimum 2 year after surgery. Results The mean postoperative knee flexion angles were similar between overstuffed resurfacing group and patelloplasty group (132 ± 7° vs. 134 ± 8°, 95% confidence interval [CI] − 6.9–1.8°, p = 0.1). The mean increase in postoperative knee flexion was 13° in both groups ( p = 0.94). The mean change of overall modified WOMAC score was also similar between the two groups (42 ± 12 vs. 39 ± 9 points, 95% CI − 1.7–9.4 points, p = 0.17). Conclusion This study demonstrated that increased patellar thickness has no effect on postoperative knee flexion angle and functional outcomes in TKA. The finding clarified the misunderstanding principle of native patellar thickness restoration after resurfacing which had made many surgeons to refrain from resurfacing especially in patient who had thin patella.