Abstract: BACKGROUND: The use of 3D-printed patient-specific instruments in opening wedge high tibial osteotomy has advantages such as shorter operative time, fewer fluoroscopic exposures, and higher correction accuracy. However, previous studies have reported issues such as significant damage to surrounding soft tissues and improper fixation of the plates. 
OBJECTIVE: To investigate the clinical efficacy of using 3D-printed patient-specific instruments combined with customized locking plate in opening wedge high tibial osteotomy for the treatment of knee osteoarthritis. 
METHODS: A total of 20 patients diagnosed with knee osteoarthritis were divided into the 3D group (n=10) and the conventional group (n=10) according to surgical methods. The 3D group underwent opening wedge high tibial osteotomy using 3D-printed patient-specific instruments combined with customized locking plate, while the conventional group underwent opening wedge high tibial osteotomy using conventional methods. The operative time, fluoroscopic exposures, incision length, pre- and postoperative hip-knee-ankle angle, medial proximal tibial angle, posterior tibial slope, the difference between the planned and actual correction angle, preoperative and 1, 3, 6 months postoperative knee range of motion and Lysholm score, and incidence of complications were analyzed and compared between the two groups. 

RESULTS AND CONCLUSION: (1) The operative time and fluoroscopic exposures were significantly shorter in the 3D group compared to the conventional group, with a statistically significant difference (P < 0.001). (2) Both groups showed a significant improvement in postoperative hip-knee-ankle angle and medial proximal tibial angle compared to preoperative values, with a statistically significant difference (P < 0.001), while there was no significant change in posterior tibial slope. In the 3D group, the postoperative hip-knee-ankle angle, medial proximal tibial angle, and posterior tibial slope differed from their respective preoperative planned values by (-0.22±0.72)°, (-0.20±0.73)°, and (0.23±0.37)°, but the differences were not statistically significant. The difference between the planned and actual correction angle of 3D group was significantly smaller than that of conventional group (P < 0.05). (3) Both groups showed a gradual increase in knee range of motion and Lysholm scores after surgery (P < 0.001). Compared to the conventional group, the 3D group had superior knee range of motion at 1 and 3 months postoperatively, as well as a higher Lysholm score at 1 month postoperatively, with statistically significant differences (P < 0.05). There were no statistically significant differences in Lysholm score at 3 months and knee range of motion and Lysholm score at 6 months between the two groups (P > 0.05). (4) Complications occurred in neither groups. (5) The above results indicate that both 3D-printed patient-specific instruments combined with customized locking plate and conventional methods have good clinical efficacy. However, the former has a shorter operative time, fewer fluoroscopic exposures, and faster postoperative recovery of knee joint function. Additionally, 3D-printed patient-specific instruments can achieve preoperative planning accurately.

中国组织工程研究杂志出版内容重点：人工关节；骨植入物；脊柱；骨折；内固定；数字化骨科；组织工程

Key words: 3D printing, patient-specific instruments, customized locking plate, opening wedge high tibial osteotomy, knee osteoarthritis