Patella resurfacing is not associated with a difference in the Oxford knee score after total knee arthroplasty but stair descent is enhanced

Background The primary aim was to assess the Oxford knee scores (OKS) on patients who underwent a total knee arthroplasty (TKA) with patellar resurfacing compared to those who did not. Secondary aims were to identify: (1) factors associated with resurfacing, (2) the effect of resurfacing on specific components of the OKS related to patellofemoral function, (3) the influence on patient satisfaction, and (4) whether a subgroup of patients had an improved outcome when resurfacing was undertaken. Methods A retrospective cohort study was undertaken using outcome data from the arthroplasty database held at the study centre. Patient demographics and OKS were collected preoperatively and at 1 and 2 years postoperatively. Patient satisfaction was assessed at 1 and 2 years postoperatively. Results Three thousand one hundred and twenty-two patients met the inclusion criteria of which 46.5% ( n = 1453) underwent resurfacing. There were no differences in the OKS change at 1 or 2 years between those undergoing and not undergoing resurfacing (difference 0.2, p ≥ 0.469). Patients undergoing resurfacing were more likely to be female (odds ratio (OR) 1.53, 95% CI 1.30–1.79, p < 0.001), undergo a posterior stabilised knee (OR 6.87, 95% CI 5.71–8.27, p < 0.001) or had a worse response to question 5—standing from a chair, ( p = 0.011) or 12—stair descent, ( p = 0.017) of the OKS preoperatively. There was no difference in postoperative patient satisfaction ( p ≥ 0.180). There was a significantly greater improvement in question 12 of the OKS at 1 year ( p = 0.019) in the resurfaced group. There were no patient-related factors or symptoms that were associated with a clinically significant (≥ 5 points) greater postoperative OKS. Conclusion Patella resurfacing was not associated with a clinically important improvement in OKS. No specific indications for patella resurfacing were identified that offered an improved outcome, but when it was undertaken there was a greater improvement in the ability to descend stairs. Level of evidence Retrospective diagnostic study, Level III.