Patellofemoral osteoarthritis does not influence clinical outcomes of fixed-bearing unicompartmental knee arthroplasty

Unicompartmental knee arthroplasty (UKA) is an ideal surgical approach in treatment of end-stage knee osteoarthritis (KOA), however, indications of UKA have been controversial, and the radiographic and symptomatic patellofemoral osteoarthritis (PFOA) are often considered as a contraindication of medial UKA. 337 fixed bearing UKAs were retrospectively recruited in our joint center between January 1, 2011 and June 30, 2020. There were 105 patients accompanied by PFOA and 232 patients have normal PF joint. International Cartilage Repair Society (ICRS) system was introduced to quantify the degeneration degree of PF joint. Oxford Knee Score (OKS), Forgotten Joint Score (FJS), Kellgren-Lawrence (K-L) classifying system and visual analogue scale (VAS) were adopted to evaluate outcomes between with and without PFOA. There was no significant difference of age, BMI, gender, OKS, FJS and other variables between PFOA and Non-PFOA group. After more than 5 years follow-up, UKA patients with or without PFOA could all achieve a satisfactory improvement of OKS, VAS and FJS score. ROM of the replaced knee increased from preoperative 110° to 130°. 74.3% (78/105) and 75.0% (174/232) patients have no change of K-L grade in PFOA and Non-PFOA group, OKS, FJS, VAS score and ROM were also comparable in all patients and no significant outcomes difference were found between two group. The presence of patellofemoral joint osteoarthritis and anterior knee pain should not be considered to be contraindications to medial fixed-bearing UKA.