TakeuchiⅢ型合页骨折是内侧开放胫骨高位截骨（MOWHTO）一种严重的术中并发症，会导致截骨端力学稳定性下降，影响预后，评价在原有内固定基础上加用辅助固定系统（AFS）后截骨端力学稳定性的改变，为Ⅲ型合页骨折的治疗提供新思路。

采用CT扫描的人体下肢骨骼数据和TomoFix钢板、螺钉建立完整合页的MOWHTO模型A和Ⅲ型合页骨折的模型B，在模型B基础上加用AFS构建模型C。模拟由坐到起立、行走、扭转状态，分别在模型胫骨平台上方加载不同载荷，测量内固定物最大应力和内侧截骨端及外侧合页部位最大移位情况，评估截骨端力学稳定性的变化。

由坐到起立状态下，相较模型A，模型B、C钢板最大应力分别增加了85.5%、25.3%；内侧截骨端最大移位量分别增加了6.0%，3.7%；外侧合页部位最大移位量分别增加了19.2%、10.1%。行走状态下钢板最大应力分别增加了62.8%、14.4%；内侧截骨端最大移位量分别增加了-3.4%、-6.9%；外侧合页部位最大移位量分别增加了106.4%、89.3%。扭转载荷下钢板最大应力分别增加了25.5%、-10.2%；内侧截骨端最大移位量分别增加了16.8%、9.3%；外侧合页部位最大移位量分别增加了8.5%，1.6%。

本研究表明，Ⅲ型合页骨折使截骨端稳定性下降，可导致钢板内固定应力和外侧胫骨平台骨折端移位增加；在由坐到起立状态下对截骨端稳定性影响最大，因此需要尽量避免或在保护下做动作；AFS可以分散内固定物的应力，减少胫骨平台骨折端的移位，提高截骨端稳定性，理论上可减少内固定物失效、术后力线丢失、截骨端不愈合的发生率，相较单纯原有内固定可以更早部分负重，更安全早期功能锻炼，有利于快速康复，减少并发症，可考虑用于Ⅲ型合页骨折的治疗，但仍需进一步的生物力学研究来证实。

Takeuchi type III hinge fracture is a serious intraoperative complication of medial open wedge high tibial osteotomy (MOWHTO), which can lead to a decrease in the mechanical stability of the osteotomy site and affect the prognosis. This study evaluated the changes in the mechanical stability of the osteotomy site after adding an auxiliary fixation system (AFS) to the original internal fixation, with an aim of providing new ideas for the treatment of type III hinge fractures.

CT scan data of human lower limb bones and TomoFix plates and screws were used to establish the intact hinge MOWHTO model A and type III hinge fracture model B. Model C was constructed by adding an AFS on the basis of model B. Sitting to standing, walking, and twisting states were simulated. Different loads were applied above the tibial plateau of the models. The maximum stress of the internal fixation and the maximum displacement of the medial osteotomy site and the lateral hinge part were measured to evaluate the changes in the mechanical stability of the osteotomy site.

From the sitting to standing state, compared with model A, the maximum stresses of the plates in models B and C increased by 85.5% and 25.3%, respectively; the maximum displacement at the medial osteotomy site increased by 6.0% and 3.7%, respectively; and the maximum displacement at the lateral hinge position increased by 19.2% and 10.1%, respectively. In the working state, the maximum stress of the plates in models B and C increased by 62.8% and 14.4%, respectively; the maximum displacement at the medial osteotomy site increased by -3.4% and -6.9%, respectively; and the maximum displacement at the lateral hinge position increased by 106.4% and 89.3%, respectively. Under torsional load, the maximum stresses of the plates in models B and C increased by 25.5% and -10.2%, respectively; the maximum displacement at the medial osteotomy site increased by 16.8% and 9.3%, respectively; and the maximum displacement at the lateral hinge position increased by 8.5% and 1.6%, respectively.

This study demonstrates that type III hinge fractures reduce the stability of the osteotomy site, leading to an increase in the stress of the plate internal fixation and the displacement of the fracture site on the lateral tibial plateau. It has the greatest impact on the stability of the osteotomy site during the sit-to-stand transition, necessitating either avoidance of the movement or implementation of protective measures. AFS can distribute the stress of the internal fixation device, reduce the displacement of the fracture site on the tibial plateau, improve the stability of the osteotomy site, theoretically reducing the incidence of failure of the internal fixation device, loss of the alignment, and non-union of the osteotomy site. Compared with the original internal fixation, AFS can partially bear weight earlier, provide safer early functional exercise, facilitate rapid recovery, and reduce complications. It can be considered for the treatment of type Ⅲ hinge fractures. However, further biomechanical studies are needed to confirm this finding.