股骨粗隆间骨折三种内侧支撑的力学分析

A mechanical comparison of 3 types of medial cortical support for reduction and fixation of femoral intertrochanteric fractures

[目的]通过生物力学研究,分析3种类型股骨粗隆间骨折内侧阳性、中性及阴性支撑下的稳定性差异。[方法]使用SYNBONE人工股骨标准试验骨分别制作A1.1/A2.1/A3.2 3种粗隆间骨折模型,并使用股骨近端抗旋髓内固定,根据不同的复位状态分为阳性、中性及阴性支撑组,通过静态轴向压缩试验分析在不同载荷下的股骨近端下沉位移值以及模型轴向刚度值。[结果] A1.1型骨折阳性及中性支撑模式股骨近端下沉位移均小于阴性支撑,且前2模式的轴向刚度均大于阴性支撑模式(P<0.05)。A2.1型骨折股骨近端下沉位移依次为:阳性支撑<中性支撑<阴性支撑;刚度依次为阳性支撑>中性支撑>阴性支撑;组间差异均有统计学意义(P<0.05)。A3.2型骨折中性支撑组位移显著小于阳性支撑及阴性支撑,而刚度显著大于后两者(P<0.05)。[结论]内侧皮质阳性支撑可视为A1.1和A2.1型粗隆间骨折的最优复位状态,而A3.2型反粗隆间骨折应最大程度获得解剖复位中性支撑。

[Objective] To compare the mechanical characteristics of 3 types of medial cortical supports, including the positive, neutral and negative, for reduction and fixation of intertrochanteric fractures. [Methods] A total 36 synthetic femur bones(Synbone) were used to simulate 3 types of femoral intertrochanteric fractures, including AO/OTA type-A1.1, A2.1 and A3.2. The fractures were fixed in positive,neutral and negative medial cortical support states with proximal femoral nail anti-rotation. As static axial compression loading added, the proximal femur subsidence displacement and the axial stiffness of the models were measured. [Results] For type-A1.1 fracture, the positive and neutral support modes had significantly less proximal femur displacement(P<0.05), whereas significantly greater axial stiffness than the negative support mode(P<0.05). In term of type A2.1 fractures, the displacement ranked down-up in a sequence of positive support <neutral support < negative support, whereas the stiffness arranged in order up-down of positive support > neutral support > negative support, with statistical significances among the 3 support modes in displacement and axial stiffness(P<0.05). Regarding to type A3.2 fracture,the neutral support mode had significantly less proximal femur displacement, whereas significantly greater axial stiffness than the positive support and the negative support modes(P<0.05). [Conclusions]The positive medial cortical support might be considered as the optimal reduction state for AO/OTA type-A1 and A2 intertrochanteric fractures, whereas neutral medial cortical support might be suitable choice for the AO/OTA type A3 trochanteric fractures with reverse oblique fracture line, which should be reduced to anatomic state as much as possible.