Orthopaedic Engineering Research Laboratory, Carolinas Medical Center, Charlotte, NC.
Department of Orthopaedic Surgery, University of Iowa, Iowa, IA.
J Orthop Trauma. 2019 Feb;33(2):92-96. doi: 10.1097/BOT.0000000000001341.
Far cortical locking (FCL) constructs have been shown to increase axial interfragmentary displacement while limiting shear and have been specifically recommended in the treatment of distal femur fractures. However, there is no available data regarding their mechanical behavior within the range of bridge spans typically used for comminuted distal femur fractures. This biomechanical study of distal femur locked plate fixation assessed 4 methods of diaphyseal fixation for associated axial and shear displacement at bridge spans typically used in clinical practice.
Distal femur locking plates were used to bridge simulated fractures in femur surrogates with 4 different methods of diaphyseal fixation (bicortical locking, bicortical nonlocking, near cortical locking, and FCL). Axial and shear displacement were assessed at 5 different bridge spans for each fixation method.
Diaphyseal fixation type was associated with the amount of shear (P = 0.04), but not the amount of axial displacement (P = 0.39). Specifically, FCL constructs demonstrated greater shear than bicortical locking (median 4.57 vs. 2.94 mm, P = 0.02) and bicortical nonlocking (median 4.57 vs. 3.41 mm, P = 0.02) constructs.
Unexpectedly, FCL constructs demonstrated greater shear than bicortical locking and nonlocking constructs and similar axial displacement for all fixation methods. Bridge span had a dominant effect on displacement that interacted negatively with more flexible FCL diaphyseal fixation. Potentially interactive construct features are best studied in concert. Given the complexity of these relationships, computational modeling will likely play an integral role in future mechanotransduction research.
远皮质锁定（FCL）结构已被证明可增加轴向骨折块间位移，同时限制剪切，并特别推荐用于治疗股骨远端骨折。然而，目前尚无关于其在用于粉碎性股骨远端骨折的桥跨范围内的机械行为的可用数据。本研究通过生物力学研究评估了在临床实践中通常使用的桥跨范围内，用于固定股骨远端锁定板的 4 种骨干固定方法，以评估与轴向和剪切位移相关的骨干固定方法。
使用股骨替代物上的远端股骨锁定板来桥接模拟骨折，有 4 种不同的骨干固定方法（双皮质锁定、双皮质非锁定、近皮质锁定和 FCL）。对于每种固定方法，在 5 个不同的桥跨位置评估轴向和剪切位移。
骨干固定类型与剪切量有关（P=0.04），但与轴向位移量无关（P=0.39）。具体而言，FCL 结构比双皮质锁定（中位数 4.57 与 2.94mm，P=0.02）和双皮质非锁定（中位数 4.57 与 3.41mm，P=0.02）结构的剪切量大。
出乎意料的是，FCL 结构比双皮质锁定和非锁定结构的剪切量大，但所有固定方法的轴向位移相似。桥跨对位移有主导作用，与更灵活的 FCL 骨干固定呈负交互作用。潜在的相互作用结构特征最好协同研究。鉴于这些关系的复杂性，计算建模可能在未来的力学研究中发挥重要作用。
