Abstract:[Objective] To evaluate the clinical efficiency of 3D printing-assisted high tibial osteotomy (HTO) in the treatment of varusknee osteoarthritis (KOA). [Methods] A retrospective study was performed on 94 patients who received HTO for varus KOA treated from Jan-uary 2018 to June 2019. According to doctor-patient communication, 47 patients received 3D printing-assisted HTO, while the other 47 pa-tients received traditional freehand HTO. The perioperative, follow-up and imaging data of the two groups were compared. [Results] The 3Dgroup proved significantly superior to the freehand group in terms of operative time [(58.8±5.0) min vs (65.8±5.4) min, P<0.001] and intraop-erative fluoroscopic frequency [(2.1±0.9) times vs (7.5±1.6) times, P<0.001]. All the patients in both groups were followed up for more than24 months. The flexion-extension range of motion (ROM), VAS, WOMAC, and HSS scores significantly improved over time in both groups(P<0.05). The 3D group was significantly better than the freehand group regarding to flexion-extension ROM [(96.8±5.8)° vs (88.7±5.2)°, P<0.001], VAS sore [(5.7±1.1) vs (6.6±1.4), P<0.001], WOMAC score [(28.7±3.9) vs (34.8±4.0), P<0.001] and HSS score [(58.5±7.0) vs (53.3±6.9), P<0.001] 6 months postoperatively. Radiographically, the femorotibial angle (FTA), medial proximal tibial angle (MPTA), and Kellgren-Lawrence (K-L) scale for osteoarthritis of the medial compartment significantly improved in both groups at the latest follow-up comparedwith those before surgery (P<0.05), however, the posterior tibial slope (PTS) and K-L scale of the lateral compartment remained unchangedin both of them between the two time points (P>0.05). In addition, there were no significant differences in FTA, MPTA, PTS, and K-L scalesbetween the two groups at any time points accordingly (P>0.05). [Conclusion] The 3D print-assisted HTO does bolster accuracy of the oste-otomy, enhance surgical efficiency and improve the clinical outcomes for treatment of varus KOA.