ObjectiveTo investigate the efficiency of total knee arthroplasty (TKA) for varus osteoarthritic knees with tibial bone resection determined by lateral tibiofemoral joint 90° flexional gap measurement. MethodsBetween March and June 2013, 60 patients (60 knees) with varus osteoarthritic knees underwent TKA. All patients were randomly divided into traditional osteotomy group (control group, 30 cases) and lateral tibiofemoral joint 90° flexional gap measurement resection group (trial group, 30 cases). There was no significant difference in gender, age, affected side, body mass index and preoperative knee society score (KSS), range of motion (ROM) of the knee, anatomic tibiofemoral angle (ATFA), patellar tilt angle, posterior condylar offset (PCO), and joint line height between 2 groups (P>0.05). The bone resection thickness of the distal femoral lateral condyle, femoral posterior lateral condyle, and lateral tibial plateau were measured; and the X-ray films were taken to measure and compare ATFA, patellar tilt angle, PCO, and joint line height after TKA. The knee function recovery was evaluated with KSS score and ROM of the knee. ResultsThe bone resection thickness of the lateral tibial plateau and distal femoral lateral condyle in trial group was significantly smaller than that in control group (P<0.05); while the bone resection thickness of the femoral posterior lateral condyle was significantly bigger than that in control group (P<0.05). The 10 mm polyethylene insert was used in 19 cases of the trial group and in 8 cases of the control group, showing significant difference (Z=-4.040, P=0.003). All the patients were followed up 13-16 months (mean, 14.5 months). Radiography at 6 weeks after TKA indicated that the ATFA, patellar tilt angle, and joint line height had no significant difference between 2 groups (P>0.05); the PCO of trial group was significantly lower than that of control group (P<0.05). The KSS score and ROM of the knee at 12 months after operation were significantly improved when compared with preoperative ones in 2 groups (P<0.05), and trial group was significantly better than control group (P<0.05). ConclusionIt was an effective method to determine bone resection thickness using lateral tibiofemoral joint 90° flexional gap measurement in TKA for varus osteoarthritic knees, which can reduce the bone resection thickness of the tibial plateau and distal femoral lateral condyle and restore the joint line and PCO with better early recovery of the knee function.