Department of Orthopaedic Surgery, St. Mary's Medical Center, 450 Stanyan Street, 94117 San Francisco, CA, USA.
Department of Orthopaedic Surgery, St. Mary's Medical Center, 450 Stanyan Street, 94117 San Francisco, CA, USA.
Orthop Traumatol Surg Res. 2024 Oct;110(6):103868. doi: 10.1016/j.otsr.2024.103868. Epub 2024 Mar 11.
Distal femur fractures are difficult to successfully treat due to high rates of nonunion. Obesity is an independent prognostic risk factor for nonunion. Advances in finite element analyses (FEAs) have allowed researchers to better understand the performance and behavior of constructs at the bone-implant interface under a variety of conditions. The purpose of this study is to determine the impact of body weight on fracture strain in a lateral locking plate construct for supracondylar femur fractures and whether additional construct rigidity is beneficial to optimize fracture strain in high body mass patients.
We hypothesized that increased loads would produce a higher interfragmentary strain (IFS), which could be decreased by shortening the working length of the construct.
A 3D finite element analysis was performed on two separate femur models with a comminuted supracondylar distal femur fracture fixed with a lateral distal femoral locking plate in bridging mode with Ansys software. Axial forces were varied to recreate the effect of load from normal and high body mass patients. Working length and screw density of the construct were varied for each condition. Measurements of interfragmentary strain and shear motion (SM) were compared.
Doubling the axial load from 70kg (control) to 140kg (high body mass) increased the interfragmentary strain by an average of 76% for the three working lengths (3.38%±1.67% to 4.37%±0.88% at the baseline working length (BWL), 1.42%±1.00% to 2.87%±2.02% at the intermediate working length (IWL) and 0.62%±0.22% to 1.22%±0.42% at the short working length (SWL)). On average, decreasing the working length in the 140kg load reduced the mean IFS to within 15% of the mean IFS of the 70kg load at the longer working length (2.87%±2.02% at IWL 140kg versus 3.38%±1.67% at BWL 70kg and 1.22%±0.45% SWL 140kg versus 1.42±1.00% IWL 70kg).
Increased axial load increases interfragmentary strain in an AO/OTA 33A distal femur fracture fixed with a lateral distal femoral locking plate. Decreasing the working length of the fixation construct in the high body mass model decreased interfragmentary strain. Higher loading conditions reflective of high body mass patients should be considered in studies investigating optimization of fracture strain.
V; Finite Element Analysis (FEA).
由于股骨远端骨折的非愈合率较高，因此很难成功治疗。肥胖是影响非愈合的独立预后危险因素。有限元分析（FEA）的进步使研究人员能够更好地了解在各种条件下骨-植入物界面的结构的性能和行为。本研究的目的是确定体重对髁上股骨骨折侧方锁定钢板固定的骨折应变的影响，以及额外的结构刚性是否有利于优化高体重患者的骨折应变。
我们假设增加的负荷会产生更高的断端间应变（IFS），通过缩短结构的工作长度可以降低 IFS。
使用 Ansys 软件对两个单独的股骨模型进行了 3D 有限元分析，这些模型均存在粉碎性髁上远端股骨骨折，采用侧方远端股骨锁定钢板以桥接模式固定。改变轴向力以模拟正常和高体重患者的负荷影响。为每种情况改变了结构的工作长度和螺钉密度。比较了断端间应变和剪切运动（SM）的测量值。
将轴向负荷从 70kg（对照）增加到 140kg（高体重），三种工作长度的断端间应变平均增加了 76%（基线工作长度（BWL）时为 3.38%±1.67%至 4.37%±0.88%，中间工作长度（IWL）时为 1.42%±1.00%至 2.87%±2.02%，短工作长度（SWL）时为 0.62%±0.22%至 1.22%±0.42%）。平均而言，在 140kg 负荷下缩短工作长度将使较短工作长度的平均 IFS 降低到与较长工作长度的 70kg 负荷的平均 IFS 相差 15%以内（IWL 140kg 时为 2.87%±2.02%，BWL 70kg 时为 3.38%±1.67%，SWL 140kg 时为 1.22%±0.45%）。
在使用侧方远端股骨锁定钢板固定的 AO/OTA 33A 远端股骨骨折中，增加轴向负荷会增加断端间应变。在高体重模型中缩短固定结构的工作长度会降低断端间应变。在研究优化骨折应变时，应考虑反映高体重患者的更高负荷条件。
V；有限元分析（FEA）。
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