Orthopaedics and Rehabilitation, Yale University School of Medicine, 47 College Place, New Haven, CT 06510, USA; Biomedical Engineering, Yale University School of Engineering & Applied Science, 17 Hillhouse Avenue, New Haven, CT 06520, USA.
Orthopaedics and Rehabilitation, Yale University School of Medicine, 47 College Place, New Haven, CT 06510, USA.
Clin Biomech (Bristol). 2023 Dec;110:106129. doi: 10.1016/j.clinbiomech.2023.106129. Epub 2023 Oct 18.
The locking plate is a common device to treat distal femur fractures. Healing is affected by construct stiffness, thus many surgeon-controlled variables such as working length have been examined for their effects on strain at the fracture. No convenient analytical model which aids surgeons in determining working length has yet been described. We propose an analytical model and compare it to finite element analysis and cadaveric biomechanical testing.
First, an analytical model based on a cantilever beam equation was derived. Next, a finite element model was developed based on a CT scan of a "fresh-frozen" cadaveric femur. Third, biomechanical testing in single-leg stance loading was performed on the cadaver. In all methods, strain at the fracture was recorded. An ANCOVA test was conducted to compare the strains.
In all models, as the working length increased so did strain. For strain at the fracture, the shortest working length (35 mm) had a strain of 8% in the analytical model, 9% in the finite element model, and 7% for the cadaver. The longest working length (140 mm) demonstrated strain of 15% in the analytical model, and the finite element and biomechanical tests both demonstrated strain of 14%.
The strain predicted by the analytical model was consistent with the strain observed in both the finite element and biomechanical models. As demonstrated in existing literature, increasing the working length increases strain at the fracture site. Additional work is required to refine and establish validity and reliability of the analytical model.
锁定钢板是治疗股骨远端骨折的常用装置。愈合受结构刚度的影响，因此许多外科医生控制的变量（如工作长度）已被研究其对骨折处应变的影响。目前还没有描述一种方便的分析模型，帮助外科医生确定工作长度。我们提出了一种分析模型，并将其与有限元分析和尸体生物力学测试进行了比较。
首先，基于悬臂梁方程推导出一个分析模型。接下来，根据“新鲜冷冻”尸体的 CT 扫描建立了一个有限元模型。第三，在单腿站立负荷下对尸体进行生物力学测试。在所有方法中，记录骨折处的应变。进行协方差分析（ANCOVA）检验以比较应变。
在所有模型中，随着工作长度的增加，应变也随之增加。对于骨折处的应变，最短工作长度（35 毫米）的分析模型中应变值为 8%，有限元模型中为 9%，尸体中为 7%。最长工作长度（140 毫米）的分析模型中应变值为 15%，有限元模型和生物力学测试均显示应变值为 14%。
分析模型预测的应变与有限元模型和生物力学模型观察到的应变一致。如现有文献所示，增加工作长度会增加骨折部位的应变。需要进一步的工作来改进和确定分析模型的有效性和可靠性。
