骨水泥强化动力髋固定效果的生物力学研究

目的：研究A2型股骨转子间骨折动力髋螺钉（DHS）固定加骨水泥强化对内固定生物力学影响。方法：24对成年男性防腐股骨上段标本，制造A2型股骨转子间骨折，采用4孔DHS固定。每对股骨以左侧为非强化组，右侧为强化组，股骨头髓腔钉道填塞骨水泥。标本进行弯曲强度，扭转强度及破坏试验。测量骨折位移，转角及最大加载力。结果：强化组和非强化组在弯曲强度，扭转强度及最大加载力有显著差异（P〈0．05），有统计学意义。相对于非强化组，骨水泥强化后弯曲强度提高148％，扭转强度提高96％，最大加载力提高67％。结论：骨水泥强化有效地增加DHS固定强度，整体提高骨折稳定性，减少内固定失败的可能性。

Biomechanical evaluation of the dynamic hip screw with bone cement augmentation

Objective: To evaluate the biomechanical effects of the dynamic hip screw (DHS) augmented with bone cement in A2 intertrochanteric fractures. Methods: Twenty-four matched pairs of embalmed male upper femora were used. All the specimens which were created unstable Type A2 intertrochanteric fracture were fixed by a four-hole DHS. The left one from each pair was designated as unaugmented team, whereas the right femur served as the augmented team. The bone cement was injected into the hip screw track. Within a servohydraulic testing machine,femoral specimens were fixed to perform the biomechanical test which included the bending stiffness, torsional stiffness and the greatest loading .The load was increased to measure the displacement of the fracture, torsional angel and the strength to the failure. Results: There was significant difference (P< 0.05) of the biomechanical effects between the augmented team and the unaugmented one. With bone cement augmentation, the bending stiffness increased by 148 percent, torsional stiffness increased by 96 percent and the greatest loading increased by 67 percent. Conclusions: Augmenting fixation with PMMA increase the intensity through improving significantly overall stability of the fracture,thereby decrease the risk of screw cutout .