Abstract: BACKGROUND: The adjustment of force lines in open wedge high tibial osteotomy can affect the retroversion of the knee joint and the height of the patella. In addition, the adjustment of force lines in open wedge high tibial osteotomy is also different according to different varus deformity. At present, the difference of weight bearing line adjustment is still controversial for the correlation index of knee joint and the function of knee joint after surgery.
OBJECTIVE: To investigate the effect of line adjustment area on postoperative knee function and joint kinematics during open wedge high tibial osteotomy. 
METHODS: Totally 76 patients with knee osteoarthritis who received open wedge high tibial osteotomy in Binzhou People’s Hospital Affiliated to Shandong First Medical University from March 2022 to March 2023 were selected, including 33 males and 43 females, all on one knee. The lateral border of the tibial plateau was considered as 100%. The position of the central intercondylar ridge of the knee joint was 0%. The weight bearing line of the affected limb was divided into two groups according to the difference of the lateral plateau area of the affected limb: the area of the force line passing through the lateral plateau of the tibial plateau (0-29%) was classified as group A (n=39), and the area of the lateral plateau of the tibial plateau was classified as group B (n=37) by 30% to 40%. The changes of tibiofemoral angle, medial proximal tibial angle, posterior inclination of tibia, and patellar height before and after operation were analyzed. The symptoms and function of the knee were evaluated by the Numeric Rating Scale score and the Hospital for Special Surgery knee score.
RESULTS AND CONCLUSION: (1) At 1 year after surgery, the posterior inclination of tibia and the medial angle of proximal tibia were increased in both groups 
(P < 0.05), and the tibiofemoral angle was reduced and patellar height was decreased in both groups (P < 0.05). The posterior inclination of tibia, medial proximal tibial angle, tibiofemoral angle, and patellar height were significantly different between the two groups at 1 year after surgery (P < 0.05). (2) The Hospital for Special Surgery knee scores of the two groups of patients at all times after surgery were better than those before surgery, and showed a gradually increasing trend (P < 0.05). There was no significant difference in the Hospital for Special Surgery knee scores 1 week and 3 months after surgery between the two groups (P > 0.05). Hospital for Special Surgery knee score of group B at 6 and 12 months after surgery was better than that of group A (P < 0.05). (3) The Numeric Rating Scale score after surgery showed a gradual downward trend (P < 0.05). No significant difference was detected between the two groups (P > 0.05). (4) The results show that the knee function and symptoms were significantly improved in the early and middle period after open wedge high tibial osteotomy, and the knee joint related parameters changed with the outward shift of weight bearing line. At 1-year follow-up, the functional recovery of knee joint in group B was better than that in group A. Long-term knee function and clinical differences after surgery need further follow-up study.

Key words: open wedge high tibial osteotomy, sports medicine, knee joint parameter, weight bearing line, knee osteoarthritis