有限动力髋螺钉内固定治疗股骨粗隆间骨折的生物力学研究

Biomechanical study of limited dynamic hip screw for treatment of femoral intertrochanteric fractures

目的通过生物力学实验测试并评价有限动力髋螺钉（Limited dynamic hip screw,LDHS）内固定治疗股骨粗隆间骨折的生物力学性能。方法采集6具新鲜尸体中12根股骨中上段标本,造成EvansⅠ、Ⅱ型股骨粗隆间骨折模型（各6根）,分别采用LDHS、DHS固定,要求将主钉安放在股骨头颈中心,且保持前倾10°-15°。LDHS组和DHS组分别进行股骨固定强度测试、刚度测试、头颈部剪断测试、扭转强度测试和极限载荷测试。结果 LDHS组与DHS组中EvansⅠ、Ⅱ型骨折模型在1200N载荷作用下,LDHS组股骨内、外侧固定强度更高,股骨头颈的轴向刚度、水平剪切刚度更高,剪切应变较小,差异均有统计学意义（P〈0.05）。在EvansⅠ、Ⅱ型骨折模型中,LDHS组最大扭矩较DHS组大,抗扭转刚度更高,但差异无统计学意义（P〉0.05）;LDHS组能承受的极限载荷较DHS组大,差异有统计学意义（P〈0.05）。结论生物力学试验表明LDHS不仅在结构设计、整体生物力学性能上优于DHS,而且置入后未发生退钉现象。LDHS可能是治疗股骨粗隆间骨折更加理想的内固定器械。

Objective To evaluate the biomechanical characteristics of the limited dynamic hip screw（LDHS） for the treatment of femoral intertrochanteric fractures by biomechanical experiment. Methods Twelve proximal femoral bones were freshly collected from 6 specimens. Either Evans＇ type Ⅰ or type Ⅱ intertrochanteric fractures was induced mechanically.Randomly, six of the fractured femoral models were fixed by LDHS and the others by DHS. The key screw must be planted in the center of the femoral neck, maintaining forward 10°-15°. Measurements of the flexural strength, elasticity, cutout,the torque resistance and the extreme pressure between the two fixation methods were compared. Results Compared to DHS,when the fractured models of Evans＇ type Ⅰ or type Ⅱ were under the 1200 N pressure, LDHS enhanced the femoral flexural strength at their inside and outside. LDHS also enhanced the femoral axial elasticity and cutout. The femoral transformation of cutout strain become reduced. There was statistical significance（P〈0.05）. Compared to DHS, in the fractured models of Evans＇ typeⅠ or type Ⅱ, LDHS enhanced the torque resistance, but there was no statistical significance（P〉0.05）. Compared to DHS, LDHS improved the extreme pressure. There was statistical significance（P〈0.05）. Conclusion Experiments show that LDHS is superior to DHS in the structure design and the overall biomechanical performance,and there was no screw failure after implantation. LDHS may be a better internal fixation device for the treatment of intertrochanteric fractures.