Abstract: BACKGROUND: There are few studies on the effect of different patellar morphologies on the outcome after unicompartmental knee arthroplasty.
OBJECTIVE: To investigate the effect of different patellar morphologies on functional recovery and patellofemoral joint alignment after unicompartmental knee arthroplasty based on patellar Wiberg classification.
METHODS: A retrospective study was conducted in 186 patients with medial knee osteoarthritis who underwent unicompartmental knee arthroplasty at Affiliated Hospital of Xuzhou Medical University between January 2022 and March 2023. Patients were categorized into group A (type I, n=43), group B (type II, n=104), and group C (type III, n=39) according to the Wiberg classification. The Hospital for Specia Surgery knee score, Feller score, and incidence of anterior knee pain, as well as radiologic data (patellar index, patellar tilt angle, and lateral patellofemoral angle) were compared among the three groups.
RESULTS AND CONCLUSION: (1) There was no significant difference in the Feller patellar score and Hospital for Specia Surgery score at the final postoperative follow-up in patients with Wiberg type I, type II, and type III patellae (P > 0.05). (2) Although there was no significant difference in the incidence of anterior knee pain among the three groups at the final follow-up, patients with type III patellae were significantly more likely to have experienced anterior knee pain early in the postoperative period. (3) Different patellar morphologies can improve patellar position to some extent after unicompartmental knee arthroplasty, but type III had greater patellar tilt than types I and II, both preoperatively and postoperatively. (4) This finding highlights the need for tailored morphological adjustments to the Wiberg III patella during unicompartmental knee arthroplasty to improve surgical outcomes. 

Key words: unicompartmental knee arthroplasty, patellar morphology, Wiberg classification, anterior knee pain, knee osteoarthritis