可灌注骨水泥动力髋螺钉内固定修复骨质疏松股骨转子间骨折的优势

背景：动力髋螺钉内固定系统被认为是治疗股骨转子间骨折的经典方法，但髋螺钉切割股骨头后位置偏移是目前常见的力学失败，需要进行二次手术。目的：在传统动力髋螺钉内固定系统的基础上，对髋螺钉部分进行改良，设计可灌注骨水泥动力髋螺钉内固定系统，探讨其治疗骨质疏松股骨转子间骨折的可行性及生物力学性能。方法：取24具新鲜完整湿润的人骨质疏松髋部标本，测量骨密度，按标准制成AO31-A1型股骨转子间骨折模型，每份骨质疏松髋部标本，其中一侧置入可灌注骨水泥动力髋螺钉内固定系统作为实验组，另一侧置入传统动力髋螺钉内固定系统作为对照组，进行轴向压缩、扭转度及失效载荷生物力学测试，比较两者生物力学性能。结果与结论：实验组应力强度、轴向刚度、水平剪切刚度高于对照组（P〈0.05）；当扭角为3°时，实验组扭矩高于对照组（P 〈0.05）；实验组失效载荷高于对照组（P 〈0.05）。表明可灌注骨水泥动力髋螺钉内固定系统治疗老年骨质疏松股骨转子间骨折，能有效增强髋螺钉的把持力，防止股骨头切割，其生物力学强度、刚度、抗疲劳性及稳定性均强于传统动力髋螺钉。

Advantages of cemented dynamic hip screw for osteoporotic intertrochanteric fracture

BACKGROUND：Dynamic hip screws have been considered as a classic method for intertrochanteric fracture. However, migration of the hip screw resulting in cut-out of the femoral head remains the most common mechanical failure, which requires secondary surgery. OBJECTIVE：On the basis of the traditional dynamic hip screw, we modified the lag screw, designed new internal fixation system as cemented dynamic hip screws to explore the feasibility and the biomechanical properties for the treatment of osteoporotic intertrochanteric fracture. METHODS：A total of 24 hip samples were harvested from fresh cadavers with osteoporosis. Bone density was measured. According to the standards, the specimens were made into intertrochanteric fracture models of AO31-A1 type. Of each specimen, one side implanted with cemented dynamic hip screws served as experimental group, and another side implanted with traditional dynamic hip screw served as control group. Axial compression, twisting and fatigue load biomechanics were tested. Their biomechanical functions were compared. RESULTS AND CONCLUSION：Stress intensity, axial stiffness and horizontal shear stiffness were higher in the experimental group than in the control group （P〈0.05）. At torsion angle of 3°, torsional moment was higher in the experimental group than in the control group （P〈0.05）. Fatigue load was higher in the experimental group than in the control group （P〈0.05）. Results suggested that cemented dynamic hip screw internal fixation system in the treatment of senile osteoporotic intertrochanteric fracture can effectively enhance the hip screw holding force and prevent femoral cutting. Biomechanical property, stiffness, endurance resistance and stability of cemented dynamic hip screw are better than traditional dynamic hip screw.