Mobile-bearing unicompartmental knee arthroplasty in old-aged patients demonstrates superior short-term clinical outcomes to open-wedge high tibial osteotomy in middle-aged patients with advanced isolated medial osteoarthritis

The aim of the present study was to compare the clinical outcomes of mobile-bearing unicompartmental knee arthroplasty (MB-UKA) and open-wedge high tibial osteotomy (OWHTO) for advanced isolated medial osteoarthritis (OA). Patients with advanced medial compartment OA (Ahlback grade ≥ II) who underwent either MB-UKA with Oxford Knee or OWHTO were included. The minimum follow-up was two years. Clinical outcomes were evaluated using the Hospital for Special Surgery (HSS) score, knee score (KS), and function score (FS) of the Knee Society Knee Scoring System. Pre-operative and post-operative values were compared within groups. Pre-operative and post-operative values and the degree of change were compared between the two groups. Radiologic progression of OA in either the lateral or patellofemoral compartment was evaluated. Forty knees (20 received MB-UKA, 20 received OWHTO) were enrolled. The mean age was higher in the MB-UKA group (67.9 ± 9.0 years) than in the OWHTO group (58.4 ± 5.5 years). The HSS score, KS, and FS were significantly increased post-operatively in both groups. The preoperative HSS score, KS, and FS were significantly lower in the MB-UKA than in the OWHTO group; however, only the post-operative HSS score was significantly higher in the MB-UKA group. The changes in HSS score and KS were also greater in the MB-UKA group. There was no significant difference in OA progression. Although there was an age difference between the two groups, MB-UKA demonstrated superior short-term clinical outcomes to OWHTO for advanced isolated medial OA. In particular, MB-UKA was more effective in terms of pain relief.