Unicompartmental Knee Arthroplasty Provides Significantly Greater Improvement in Function than Total Knee Arthroplasty Despite Equivalent Satisfaction for Isolated Medial Compartment Osteoarthritis

Abstract

Background: While some advocate for unicompartmental knee arthroplasty (UKA) for isolated medial compartment osteoarthritis (OA), others favor total knee arthroplasty (TKA). The purpose of this study was to compare the functional outcomes of UKA and TKA performed for patients with unicompartmental arthritis (OA).

Methods: A study was performed on 133 patients that met strict criteria for UKA, but who underwent either medial UKA or TKA for isolated medial compartment OA based upon physician equipoise. The primary outcome-New Knee Society Score (KSS)-was assessed preoperatively and at 2 years postoperatively. A propensity score weighted regression was used to balance the groups on several key covariates, including age, gender, body mass index, and baseline KSS.

Results: After propensity weighting, there were no significant differences between UKA and TKA in overall baseline KSS or KSS after 2 years postoperatively. While TKA patients had demonstrated a significantly greater improvement in the symptoms KSS subscale, UKA patients had a significantly greater improvement in the function subscale. Expectations were significantly more likely to be met after UKA, but there were no differences in patient satisfaction.

Conclusion: UKA and TKA are both highly successful options for treating patients with medial compartment OA, although functionality increased more, and expectations were more likely to be met, after UKA in this study. Given equivalent patient satisfaction after both TKA and UKA, surgeons should consider factors such as clinical experience, individual preference, cost of care, surgical risk, and recovery needs, when making treatment decisions regarding this clinical entity.

Keywords: knee; medial compartment osteoarthritis; outcomes; total knee arthroplasty; unicompartmental knee arthroplasty.