Comparison of clinical outcomes between mobile- and fixed-bearing unicompartmental knee arthroplasty for medial compartment osteoarthritis: a retrospective study.

BACKGROUND

Unicompartmental knee arthroplasty (UKA) is an established treatment for isolated medial compartment osteoarthritis (MCOA). The optimal choice between mobile-bearing (MB) and fixed-bearing (FB) designs remains debated, particularly in Asian populations where treatment costs and insurance policies influence surgical decisions.

OBJECTIVE

To compare short-term clinical and radiographic outcomes between MB and FB UKA and to evaluate potential implications for healthcare resource allocation.

METHODS

Sixty-four patients who underwent medial UKA between January 2022 and October 2024 were retrospectively analyzed (MB: n = 32; FB: n = 32). All surgeries were performed by a single senior surgeon using standardized protocols. Pain (Visual Analogue Scale, VAS), function (Hospital for Special Surgery [HSS] and American Knee Society Score [KSS]), radiographic alignment (femorotibial angle, FTA; tibial slope angle, STA), and range of motion (ROM) were assessed preoperatively and at 3 months postoperatively. Statistical significance was set at P < 0.05.

RESULTS

Both groups achieved significant improvements in VAS, HSS, and KSS scores (all P < 0.001), with no intergroup differences. MB showed greater correction in FTA (-3.27° vs. -2.70°, P < 0.05) and larger ROM gains in flexion and extension compared with FB (P < 0.05). No infections, loosening, or bearing dislocations occurred.

CONCLUSIONS

MB and FB UKA provide comparable short-term pain relief and functional improvement. MB may offer greater alignment correction and range of motion, whereas FB was associated with lower hospitalization cost in this cohort and may therefore have a potential economic advantage. Prosthesis selection should consider both clinical performance and economic factors to optimize patient outcomes and resource utilization.