ObjectiveTo compare the early effectiveness and safety of simultaneous bilateral and staged bilateral unicompartmental knee arthroplasty (UKA) in treatment of anteromedial compartment osteoarthritis.MethodsThe clinical data of 31 patients with bilateral anteromedial compartment osteoarthritis who underwent bilateral UKAs between January 2015 and January 2017 was retrospectively analyzed. Of them, 17 patients were treated with simultaneous bilateral UKAs (simultaneous group) and 14 patients with staged bilateral UKAs (staged group). There was no significant difference in gender, age, body mass index, osteoarthritis grading, and preoperative hip-knee-ankle angle, knee society score (KSS), visual analogue scale (VAS) score, and range of motion (ROM) of knee between the two groups (P>0.05). The operation time, blood loss, hospitalization stay, minimum hemoglobin value during 10 days after operation, and hospitalization cost were recorded. The staged group was compared by the sum of two operations. The effectiveness was evaluated by KSS score, VAS score, ROM at 3, 6, 12 months after operation, and patient satisfaction scores were recorded at 12 months after operation.ResultsThe operation time, hospitalization stay, and hospitalization cost of the simultaneous group were significantly lower than those of the staged group (P<0.05). There was no significant difference in blood loss and the minimum hemoglobin value during 10 days after operation between the two groups (P>0.05). Superficial infection occurred in 1 side of 1 case (7.1%) in staged group. Postoperative delirium occurred in 1 case (5.9%) in simultaneous group. There was no significant difference in incidence of postoperative complications between the two groups (P=1.000). Patients in both groups were followed up 12-32 months (mean, 24.7 months). There was no significant difference in KSS score between the two groups at 3 months after operation (t=0.896, P=0.392). KSS scores were significanly higher in simultaneous group than in staged group at 6 and 12 months after operation (P<0.05). There was no significant difference in ROM and VAS scores between the two groups at 3, 6, and 12 months after operation (P>0.05). At 12 months after operation, the patient satisfaction scores were significantly higher in simultaneous group than in staged group (P<0.05). X-ray films showed no loosening of the prosthesis in the two groups.ConclusionSimultaneous bilateral UKAs has the same security as staged bilateral UKAs. Meanwhile knee function recovery was better, hospitalization stay and hospitalization cost reduced, and patient satisfaction was higher in simultaneous bilateral UKAs.