Lateral unicompartmental knee arthroplasty (UKA) and total knee arthroplasty (TKA) are both reliable treatment options for patients with isolated lateral osteoarthritis (OA). However, studies comparing both procedures are scarce. Aims of this study were to (I) compare short-term functional outcomes following lateral UKA and TKA and (II) assess the role of patient characteristics on outcomes as measured by the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC).
In this retrospective cohort study, 82 patients (48 undergoing lateral UKA and 34 undergoing TKA) were identified that presented with lateral OA and completed the WOMAC. Independent t-tests were used to compare outcomes following lateral UKA and TKA.
Mean follow-up was 2.8 years (range: 2.0 – 5.0 years). Preoperatively, no differences between lateral UKA and TKA were seen (50.1 ± 13.5 and 53.3 ±17.1, respectively, p = 0.551). Postoperatively, lateral UKA patients reported better overall outcomes than TKA (90.5 ± 11.7 vs. 81.8 ± 17.9, p = 0.017). Subgroup analysis showed better outcomes following lateral UKA than TKA in patients younger than 75 years (92.1± 9.9 vs. 81.3 ± 19.6, p = 0.014) and in females (91.6 ± 9.9 vs. 81.0 ± 18.2, p = 0.014).
These findings indicate that lateral UKA has superior short-term functional outcomes compared to TKA in patients with isolated lateral OA. Better outcomes were especially seen in younger patients and females. These findings may help orthopedic surgeons choose treatment for patients presenting with lateral OA and optimize treatment for individual patients.