Outcomes of patellofemoral joint arthroplasty compared with total knee arthroplasty for osteoarthritis

Aims The surgical options for patients with osteoarthritis (OA) of the patellofemoral joint (PFJ) involve a patellofemoral joint arthroplasty (PFA) or a total knee arthroplasy (TKA). The aim of this study was to describe and compare the safety profile and risk of revision of these two procedures. Methods The records of patients from the UK National Joint Registry who underwent PFA or TKA between April 2003 and December 2021 were linked to the Hospital Episode Statistics database. Using Poisson regression, a 30-day safety profile was created by plotting risk ratios, absolute risk, and the differences in risk of myocardial infarction, respiratory tract infection, urinary tract infection (UTI), stroke, delirium, deep vein thrombosis/pulmonary embolism (DVT/PE), wound infection, and death. A parametric survival model was used to model the survival of a PFA compared with a TKA over the course of the postoperative time period. Differences in hazard ratios were plotted by sex for PFA. Confounding was handled by inverse proportional treatment weighting. The indications for revision and the length of stay in hospital were compared between the procedures. Results A total of 7,819 PFAs and 662,141 TKAs were analyzed. Patients who underwnt PFA were significantly less likely to have complications than those who underwent TKA: respiratory tract infection (risk ratio (RR) 0.65 (95% CI 0.47 to 0.90); p = 0.011), DVT/PE (RR 0.35 (95% CI 0.24 to 0.52); p < 0.001), UTI (RR 0.59 (95% CI 0.40 to 0.88); p = 0.001), wound infection (RR 0.73 (95% CI 0.57 to 0.91); p = 0.006), and death within 30 days postoperatively (RR 0.36 (95% CI 0.14 to 0.98); p = 0.045). Over ten years, PFAs had an 85% survival (95% CI 0.84 to 0.86) and TKAs had a 95% survival (95% CI 0.95 to 0.96). Within two years, the indication for revision of a PFA was most likely to be pain, while infection was the most common indication for revision of a TKA at this time. Conclusion PFA may be a safer procedure than TKA, being less likely to have complications, with a reduced length of stay. Despite an increased risk of revision, patients should still be counselled about the advantages of undergoing a PFA. Cite this article: Bone Joint J 2025;107-B(5):514–521.