Abstract:[Objective] To introduce the surgical technique and primary clinical results of medial open wedge high tibial osteotomy (MOWHTO) under Orthopilot navigation. [Methods] From August 2018 to February 2021, 34 patients (44 knees) were admitted to our hospital. Preoperative planning was performed with the “Osteotomy Master”. Registration was pefromed by OrthoPilot navigation intraoperatively, and then the osteotomy was done. The mechanical axis and varus angle were quantified by navigation to guide osteotomy. [Results] The follow-up time of 34 patients was (22.32±7.88) months. The HSS score of the last follow-up was significantly better than that before the operation (P<0.001). Compared with navigation after registered, the alignment of preoperative full-length radiographs was significantly more internal (P<0.001), and the varus was significantly greater (P<0.001). Compared with navigation after osteotomy, the alignment of postoperative full-length radiographs was significantly more internal (P<0.001), and the valgus was significantly smaller (P=0.005). There were 27 knees with satisfactory alignment on postoperative full-length radiographs, which is across 50%-62.5% of tibial plateau, and 17 knees were not satisfactory. There were 15 knees in the satisfactory group and 8 knees in the unsatisfactory group with no statistical significance (P=0.583), which the correction amount of alignment during navigation was within the range of the preoperative full-length radiographs corrected to 50%-62.5%. There were 15 knees in the satisfactory group and 4 knees in the unsatisfactory group with statistical significance (P=0.037), which the correction amount of varus during navigation was within the range of the preoperative full-length radiographs corrected to 0~3 degrees valgus. [Conclusion] MOWHTO guided by Orthopilot navigation can significantly relief symptoms. Making the correction amount of varus during navigation consistent with the range of the preoperative full-length radiographs corrected to 0~3 degrees valgus can resulting in a more satisfactory postoperative alignment.