Abstract: Objective　 To investigate the clinical efficacy of 3D printing osteotomy guide plate assisted with opening wedge high tibial osteotomy (OWHTO) combined with arthroscopic debridement for treating knee varus deformity.　Methods　15 cases patients (16 knees) with knee varus deformity in orthopedics department of our hospital from January 2017 to May 2018 were analyzed retrospectively. 3D printing osteotomy guide plate was used to simulate OWHTO before operation. According to the ideal postoperative weight-bearing line (WBL), the osteotomy site, the osteotomy hinge, the height, the width, and the posterior tibial slope (PTS) were determined to fix the osteotomy. The preoperative and postoperative WBL, Lysholm score, PTS, and patella height index (Caton index) were compared.　Results　After 15 to 24 months of follow-up, the WBL changed from preoperative (19.27±1.55) % to postoperative (60.54±0.84) % (P<0.05). There was statistical difference between the WBL before operation and the WBL after operation. The 3D printing design before operation was (61.91±0.24) %, the PTS before operation and after operation were (10.01±2.89)°, (10.06±0.09)°respectively. There were no statistical difference between the preoperative and postoperative 3D printing design and the PTS. The Lysholm score of 1 year after operation was (82.31±1.22), before operation was (34.75±1.87), there was statistical significance between the Lysholm score of 1 year after operation and after operation.　Conclusions　3D-printing technique assisted with opening wedge high tibial osteotomy combined with arthroscopy can achieve accurate osteotomy, improve the weight-bearing line significantly, reduce intraoperative perspection, save operation time, it is a safe and effective treatment of varus knee deformity.

Key words: Knee varus deformity, 　High tibial osteotomy, 　Three-dimensional printing;　Arthroscopy