Similar postoperative patient-reported outcome in both second generation patellofemoral arthroplasty and total knee arthroplasty for treatment of isolated patellofemoral osteoarthritis: a systematic review

INTRODUCTION: Due to inconsistent results and high failure rates, total knee arthroplasty (TKA) is more often used to treat isolated patellofemoral osteoarthritis (PFOA) despite the theoretical advantage of patellofemoral arthroplasty (PFA). It is perceived that second-generation PFA may have improved the outcomes of surgery. In this systematic review, the primary aim was to compare outcomes of second-generation PFA and TKA by assessment of patient-reported outcome measures (PROMs). METHODS: A systematic search was made in PubMed, Medline, Embase, Cinahl, Web of Science, Cochrane Library and MeSH to identify studies using second-generation PFA implants or TKA for treatment of PFOA. Only studies using The American Knee Society (AKSS), The Oxford Knee Score (OKS) or The Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) to report on PROMs were included. RESULTS: The postoperative weighted mean AKSS knee scores were 88.6 in the second-generation PFA group and 91.8 in the TKA group. The postoperative weighted mean AKSS function score was 79.5 in the second-generation PFA group and 86.4 in the TKA group. There was no significant difference in the mean AKSS knee or function scores between the second-generation PFA group and the TKA group. The postoperative weighted mean OKS score was 36.7 and the postoperative weighted mean WOMAC score was 24.4. The revision rate was higher in the second-generation PFA group (113 revisions [8.4%]) than in the TKA group (3 revisions [1.3%]). Progression of OA was most commonly noted as the reason for revision of PFA, and it was noted in 60 cases [53.1%]; this was followed by pain in 33 cases [29.2%]. CONCLUSION: Excellent postoperative weighted mean AKSS knee scores were found in both the second-generation PFA group and in the TKA group, suggesting that both surgical options can result in a satisfying patient-reported outcome. Higher revision rates in the second-generation PFA studies may in part be due to challenges related to patient selection. Based on evaluation of PROMs, the use of second-generation PFA seems to be an equal option to TKA for treatment of isolated PFOA in appropriately selected patients. Hopefully, this can be considered by physicians in their daily clinical work. LEVEL OF EVIDENCE: IV.