ObjectiveTo evaluate the effects of the improved precision alignment method of lower limbs mecha-nical alignment for osteoarthritis of the knee in open wedge high tibial osteotomy (OWHTO).MethodsA retrospective analysis was made on the clinical data of 62 patients (68 knees) with knee osteoarthritis in the medial compartment treated with OWHTO between January 2012 and December 2015 who accorded with the inclusion criteria. The traditional method for positioning lower limb mechanical force line was used in 29 cases (32 knees) (traditional group), and improved method for positioning lower limb mechanical force line in 33 cases (36 knees) (modified group). There was no significant difference in gender, age, side, course of disease, and osteoarthritis grading between two groups (P>0.05) with comparable. The operation time, intraoperative fluoroscopy times, and intraoperative blood loss were recorded in two groups; Before and after operation, the lower limb mechanical force line was observed on the X-ray films, which was expressed by hip-knee-ankle angle (HKA). The clinical efficacy was evaluated by the American Hospital for Special Surgery (HSS) score, and the Western Ontario and McMaster University Osteoarthritis Index (WOMAC).ResultsIncision hematoma occurred in 1 case of traditional group and was cured at 3 weeks after symptomatic treatment; and primary healing was obtained in the other patients, with no early complications. The operation time and intraoperative fluoroscopy times of the modified group were significantly lower than those of the traditional group (t=11.934, P=0.000; t=11.663, P=0.000), but there was no significant difference in blood loss between the two groups (t=0.209, P=0.835). The patients were followed up for 6 to 24 months (mean, 12.7 months) in the traditional group and for 3 to 22 months (mean, 13.2 months) in the modified group. The medial knee pain disappeared in all patients. At last follow-up, the HSS score and WOMAC score were significantly improved when compared with preoperative scores in two groups (P<0.05), but there was no significant difference between the two groups (P>0.05). Postoperative X-ray examination showed that the tibiofemoral angle was corrected in the two groups. The HKA angle at immediate after operation and last follow-up was significantly higher than angle at pre-operation in two groups (P<0.05), but there was no significant difference between at immediate after operation and at last follow-up (P>0.05).ConclusionCompared with the traditional method for positioning lower limb mechanical force line, the improved precision alignment method can reduce the times of intraoperative fluoroscopy and shorten the operation time, which reduces the radiation exposure of both doctors and patients.