中文摘要：

目的比较股骨近端髓内钉（proximal femoral nail，PFN）、动力髋螺钉（dynamic hip screw，DHS）、动力髁螺钉（dynamic condylar screw，DCS）和股骨近端锁定钢板（proximal femoral locking plate，PFLP）在固定不同类型股骨转子下骨折的生物力学性能。方法成年防腐人尸体股骨32根，随机分为PFN组、DHS组、DCS组和PFLP组，先后模拟SeinsheimerⅠ型骨折、ⅢA型骨折恢复内侧皮质完整、ⅢA型骨折移除内侧皮质和Ⅳ型骨折。在生物力学试验机上先后进行轴向压缩试验、扭转试验和轴向压缩破坏试验。测定股骨近端内、外侧的应变变化，抗压刚度，抗扭转刚度及破坏载荷。结果PFN组股骨内、外侧应变比率下降较均匀，在各骨折模型中轴向抗压刚度比率最高、扭转刚度比率最小，破坏载荷最大；DHS组和DCS组股骨内侧应变比率曲线呈向上的拱形，外侧张应变比率在内侧皮质不稳定的骨折模型中转变为较大的压应变，在各骨折模型中，DHS的轴向抗压刚度比率较PFLP小，在骨折模型Ⅱ～Ⅴ中扭转刚度比率最高，破坏载荷仅次于PFN，DCS的轴向抗压刚度比率和破坏载荷均最低，在骨折模型Ⅱ～Ⅴ中，扭转刚度比率与PFLP组相近；PFLP组内侧应变比率下降类似于PFN，但是外侧应变比率的变化不大，在各内固定组中轴向抗压刚度比率仅次于PFN组，破坏载荷较DHS低。结论对于SeinsheimerⅠ转子下骨折，四种内固定均能提供较好的稳定性；对于ⅢA转子下骨折，PFN和PFLP均可提供较为可靠地稳定固定，而在转子下内侧皮质复位，支撑作用良好的情况下，也可考虑使用DCS；对于Ⅳ转子下骨折，只有PFN能够提供较好稳定固定，但对于粉碎的骨折块较大时可以在解剖复位的情况下使用PFLP进行固定。

英文摘要：

Objective To compare the biomechanical properties of four kinds of internal fixations （PFN, DHS, DCS and PFLP） for different types of subtrochanteric fractures. Methods Thirty-two antiseptic femurs were randomly divided into four groups. After internal fixations implanted respectively, Seinsheimer type Ⅰ, type ⅢA with medial fragment restoration, type Ⅲ A with medial fragment discard and type Ⅳ subtrochanteric fracture models were sequentially produced. Each fracture model was tested under vertical load, torsional load and vertical damage load. The strain distributions on both medial and lateral side of subtrochanteric region were recorded and the compression stiffness and torsional stiffness of bone-implant composite were calcu-lated. Finally, the loads of failure were recorded. Results The stiffness ratio of PFN in each fracture model and load of failure were the highest among the four groups, but the torsional stiffness ratio was the lowest. Tension strain ratios of DHS and DCS on lateral side became higher compress strain ratio with medial fragment restored. Stiffness ratio of DHS was lower than PFLP in each fracture model, torsional stiffness ratio was the highest in fracture model Ⅱ to Ⅴ, and the load of failure was only lower than PFN. The stiffness ratio and load of failure of DCS were both the lowest, torsional stiffness ratio was similar to PFLP＇s in fracture model Ⅱ to Ⅴ. The stiffness ratio of PFLP was only lower than PFN＇s in each fracture model, but the load of failure was lower than DHS＇s. Conclusion Four kinds of internal fixations could achieve better stabilities for type Ⅰ subtrochanteric fractures. PFN and PFLP could achieve reliable stabilities for type Ⅱ A subtrochanteric fractures. And, if the medial buttress was restored, we could consider of using the DCS. For type IV subtrochanteric fractures, only PFN could provide stable fixation. However, when bone fragments are large at comminuted oart, PFLP could be chosen to fix them after anatomical reduction.