Abstract: BACKGROUND: For patients with anterior cruciate ligament re-rupture after reconstruction with abnormally increased posterior slope of the tibial plateau, anterior cruciate ligament reconstruction combined with anterior closing-wedge high tibial osteotomy was performed. However, there is a lack of precise tools for osteotomy. 
OBJECTIVE: To investigate the effectiveness of three-dimensional (3D) printed accurate osteotomy template in anterior cruciate ligament revision for patients with excessive posterior slope. 
METHODS: The medical records of 30 patients who underwent anterior cruciate ligament revision combined with anterior closing-wedge high tibial osteotomy were retrospectively collected and divided into two groups according to the operation method. The trial group (n=15) was assisted by 3D printing osteotomy guide plate. The control group (n=15) was conventional surgery. The osteotomy time, fluoroscopy times, intraoperative and 24 hours postoperative blood loss, preoperative and 3 months postoperative tibiofemoral anatomical angle, medial proximal tibial anatomical angle, posterior slope, the difference between planned posterior slope correction angle and actual correction angle, and KT-2000 side-to-side difference before operation, 3 and 24 months after operation were compared between the two groups. Lachman test and Pivot shift test were performed before operation, immediately after operation, and 24 months after operation. International Knee Documentation Committee score and Lysholm score were performed before operation, 3 and 24 months after operation.
RESULTS AND CONCLUSION: (1) The osteotomy time, fluoroscopy times, and blood loss during operation and 24 hours after operation in the trial group were significantly less than those in the control group (P < 0.05). (2) The posterior slope of the two groups decreased significantly after operation. There was no significant change in tibiofemoral anatomical angle and medial proximal tibial anatomical angle after operation. The difference between preoperative planned and postoperative actual posterior slope degree in the trial group (0.64±0.41)° was smaller than that in the control group (2.18±0.54)°, and the difference was statistically significant (P < 0.001). (3) The KT-2000 side-to-side difference was significantly reduced in both groups after surgery (P < 0.05). At 3 and 24 months after operation, there was no significant difference in KT-2000 side-to-side difference between the two groups (P > 0.05). The Lachman test and Pivot shift test of the two groups were negative immediately after operation, 3 and 24 months after operation. (4) The International Knee Documentation Committee and Lysholm scores of the two groups increased significantly after surgery (P < 0.05). At 3 months after operation, the International Knee Documentation Committee score and Lysholm score of the trial group were significantly higher than those of the control group (P < 0.05). At 24 months after operation, there was no significant difference in International Knee Documentation Committee score and Lysholm score between the two groups (P > 0.05). (5) In conclusion, with the assistance of 3D printing accurate osteotomy guide plate, anterior cruciate ligament reconstruction combined with anterior closing-wedge high tibial osteotomy is easier to operate, with shorter operation time, fewer fluoroscopy times, less intraoperative and postoperative blood loss, and faster recovery of knee joint function after operation, which has high clinical application value.

Key words: 3D printing, accurate osteotomy guide plate, closed anterior tibial osteotomy, anterior cruciate ligament revision, over-the-top, digital orthopedics