Long-Term Excellent Clinical Outcomes, High Survivorship, and Low Osteoarthritis Progression in Lateral Unicompartmental Knee Arthroplasty: A 10-Year Minimum Follow-Up

<b>Background:</b> The literature on the long-term outcomes of lateral unicompartmental knee arthroplasty (UKA) remains limited due to the lower prevalence of lateral osteoarthritis (OA) and the technical challenges of the procedure. This study aimed to assess the long-term clinical outcomes, implant survivorship, and OA progression in patients undergoing lateral UKA with a minimum follow-up of 10 years. <b>Methods:</b> This retrospective study analyzed 96 lateral UKAs from 2001 to 2013 using a cemented, fixed-bearing implant. Patients with at least 10 years of follow-up were included. Clinical outcomes were measured using range of motion (ROM), a pain visual analog scale (VAS), Knee Society Scores (KSSs), and the Forgotten Joint Score (FJS). Implant survivorship was assessed using a Kaplan-Meier analysis, while OA progression in the medial compartment was evaluated radiographically. <b>Results:</b> At a mean follow-up of 14.5 years, implant survivorship was 94.7%, with five revisions primarily due to OA progression. Significant improvements were observed in ROM, VAS, and KSS (<i>p</i> < 0.01). An increase in the Kellgren-Lawrence grade in the medial compartment was reported in 47.9% of patients. <b>Conclusions:</b> Lateral UKA provides excellent long-term outcomes, demonstrating high survivorship, significant functional improvement, and high patient satisfaction.