Gamma钉远端锁钉对股骨粗隆间骨折应力分布的影响

Biomechanical evaluation of strain distribution of the proximal femur locked with one distal screw in Gamma nail

目的：研究Ｇａｍｍａ钉固定股骨粗隆间骨折远端使用一枚锁钉是否影响股骨近端的应力分布．方法：在３对新鲜尸体股骨近端内外侧皮质上设置６枚电阻应变片，测定不同稳定状态的粗隆间骨折使用其远端一枚或两枚锁钉对股骨近端应力分布的影响．结果：随着骨折稳定性下降，Ｇａｍｍａ钉能承担大部分股骨近端尤其是经股骨矩的载荷，这虽然有利于骨折早期愈合，但不利于后期改建．远端锁钉数目不影响股骨近端的应力分布．Ｇａｍｍａ钉远端锁钉外侧有明显的应力集中．结论：Ｇａｍｍａ钉远端使用一枚锁钉不影响股骨近端应力分布，且不增加锁钉部位的应力集中，故远端使用一枚锁钉是可行的．

Objective: A biomechanical study was performed to analyze the strain distributions of proximal femurs in the experimental intertrochanceric fractures. Methods: A total number of 6 fresh cadaver femurs were selected to form two part or four part fracture models. Six straingauges were placed on the surface of medial and lateral cortices of the models to evaluate the strain alterations of proximal femurs, and the models were fixed by either one or two distal interlocking screws. Results: The Gamma nail represented the excellent biomechanical characteristics of bearing considerable amount of loading on proximal femur with the decrease of fracture stability, especially on the calcar area.The strains on proximal femurs might be available for fracture healing, but may affect bone remoldeling due to the influences of stress shielding. Conclusion: According to the results, the insertion of one or two distal interlocking screws does not change the patterns of proximal femoral strain, and stress focus is shown on the lateral cortex near the distal screw hole, which might play some role in the occurrence of secondary fracture of femur at the tip of the nail. The Gamma nail with one distal interlocking screw seems to be feasible clinically.