Department of Orthopedics, Faculty of Medicine, Thammasat University

The inclusion criteria were patients with medial of the knee with an Alhback score of 2, 3 or 4, those who were older than 40 years of age, those with a range of motion (ROM) > 90°, those with a varus deformity < 25°, and those with a flexion contracture < 20°. They were randomized into 2 groups using computer program. Group I was 50 UKAs and group II was 50 TKAs. All patients in group I received medial mobile-bearing UKA (Oxford® UKA; Zimmer Biomet, Inc, Warsaw, IN, USA) and group II received posterior stabilized fixed bearing total knee arthroplasty (Vanguard®; Zimmer Biomet, Inc, Warsaw, IN, USA). The exclusion criteria were patients with a diagnosis of spontaneous osteonecrosis of the knee (SPONK), intraoperative anterior cruciate ligament (ACL) insufficiency or completely rupture of ACL, inflammatory joint disease, gout, posttraumatic arthritis, or primary patellofemoral arthritis.The recorded baseline patient characteristics included age and sex and the knee side, Knee Society Score (KSS), Oxford Knee Score (OKS), Knee Injury and Osteoarthritis Outcome Score (KOOS),(2MWT), (6MWT), (TUG), body mass index (BMI), degree of varus deformity, degree of flexion contracture, genu recurvatum, and ROM. Patients were followed at 6 weeks, 3 months, 6 months, and 1 year and then annually thereafter. At each follow-up, the following data were recorded: Joint Forgotten Score (JFS), KSS, OKS, Knee Injury and Osteoarthritis Outcome Score (KOOS), Kujala score, (2MWT), (TUG), ROM and knee alignment. In addition, the following knee X-rays were performed: anteroposterior (AP) and lateral standing, skyline and long-leg views; from these, the tibiofemoral angles were measured. Complications such as infection, component loosening, fractures, and bearing dislocations were also recorded. We determined differences in the KSS, OKS, KOOS, JFS, Kujala score,(2MWT), (TUG),ROM, tibiofemoral angle, flexion contractures, and genu recurvatum using Student's t tests. All analyses were two sided, and a p value of ≤ 0.05 denoted statistical significance.