髓内钉固定骨折面是治疗髋关节骨折的主要方法, 髓内固定系统的力学可靠性是确保治疗成功的关键. 针对股骨转子间骨折, 构建了计及股骨层状结构特点和肌肉力作用的髓内固定系统有限元模型, 模拟分析了缓步行走条件下固定系统的力学响应. 为定量化评估髓内固定系统的力学可靠性, 提出安全因数的概念, 并基于这一概念定量化考察了头钉定位参数对固定系统力学可靠性的影响. 研究表明, 固定系统在股骨与头钉、主钉与头钉, 以及主钉与锁钉的接触区存在明显的应力集中, 是评估髓内固定系统力学可靠性的关键区域. 研究还表明, 髓内固定系统具有良好的力学可靠性, 降低头钉高度有利于提高髓内固定系统的力学可靠性, 而头钉近端钉角 (proximal nail angle) 对固定系统可靠性的影响可以忽略.

Intramedullary nail fixation of the fracture surface is the primary method of hip fracture treatment, and its mechanical reliability is key to ensuring treatment success. In this study, a finite element model of an intramedullary fixation system (IFS) for intertrochanteric fractures was constructed. This model considers the layered structure of the femur and muscle forces. The mechanical response of the IFS was simulated under slow walking conditions. The concept of a safety factor was proposed to quantitatively evaluate the mechanical reliability of the IFS. Based on this concept, the influence of the positioning parameters of a lag screw on the reliability of the IFS was systematically investigated. Severe stress concentrations are found at the contact regions between the femur and the lag screw, between the trochanteric nail and the lag screw, and between the trochanteric nail and the locking screw. These stress concentration regions play an important role in determining the mechanical reliability of the IFS. This study also showed that the IFS has good mechanical reliability. Reducing the lag screw height improves the mechanical reliability of the system, whereas the effect of the proximal nail angle on the reliability is negligible.