PDF(Pubmed)
Abstract：
BACKGROUND: Basicervical femoral neck fracture is a rare proximal femur fracture with a high implant failure rate. Biomechanical comparisons between cephalomedullary nails (CMNs) and dynamic hip screws (DHSs) under torsion loading are lacking. This study compared the biomechanical performance of three fixations for basicervical femoral neck fractures under torsion load during early ambulation.
METHODS: The biomechanical study models used three fixations: a DHS, a DHS with an anti-rotation screw, and a short CMN. Finite element analysis was used to simulate hip rotation with muscle forces related to leg swing applied to the femur. The equivalent von Mises stress (EQV) on fixation, fragment displacement, and strain energy density at the proximal cancellous bone were monitored for fixation stability.
RESULTS: The EQV of the short CMN construct (304.63 MPa) was comparable to that of the titanium DHS construct (293.39 MPa) and greater than that of the titanium DHS with an anti-rotation screw construct (200.94 MPa). The proximal fragment displacement in the short CMN construct was approximately 0.13 mm, the greatest among the constructs. The risk of screw cutout for the lag screw in short CMNs was 3.1-5.8 times greater than that for DHSs and DHSs with anti-rotation screw constructs.
CONCLUSIONS: Titanium DHS combined with an anti-rotation screw provided lower fragment displacement, stress, and strain energy density in the femoral head than the other fixations under torsion load. Basicervical femoral neck fracture treated with CMNs may increase the risk of lag screw cutout.
METHODS: The biomechanical study models used three fixations: a DHS, a DHS with an anti-rotation screw, and a short CMN. Finite element analysis was used to simulate hip rotation with muscle forces related to leg swing applied to the femur. The equivalent von Mises stress (EQV) on fixation, fragment displacement, and strain energy density at the proximal cancellous bone were monitored for fixation stability.
RESULTS: The EQV of the short CMN construct (304.63 MPa) was comparable to that of the titanium DHS construct (293.39 MPa) and greater than that of the titanium DHS with an anti-rotation screw construct (200.94 MPa). The proximal fragment displacement in the short CMN construct was approximately 0.13 mm, the greatest among the constructs. The risk of screw cutout for the lag screw in short CMNs was 3.1-5.8 times greater than that for DHSs and DHSs with anti-rotation screw constructs.
CONCLUSIONS: Titanium DHS combined with an anti-rotation screw provided lower fragment displacement, stress, and strain energy density in the femoral head than the other fixations under torsion load. Basicervical femoral neck fracture treated with CMNs may increase the risk of lag screw cutout.
摘要：
背景：股骨颈基颈骨折是一种罕见的股骨近端骨折，植入物失败率高。缺乏扭转载荷下头髓内钉（CMNs）和动力髋螺钉（DHSs）之间的生物力学比较。本研究比较了三种固定方法在扭转负荷下早期下床活动时股骨颈骨折的生物力学性能。
方法：生物力学研究模型使用三种固定方法：DHS，带有防旋转螺钉的国土安全部，一个简短的CMN。使用有限元分析来模拟髋部旋转，其中肌肉力量与施加到股骨的腿部摆动有关。固定时的等效vonMises应力(EQV)，碎片移位，和近端松质骨的应变能密度监测固定稳定性。
结果:短CMN构建体的EQV(304.63MPa)与钛DHS构建体的EQV(293.39MPa)相当,并且大于具有抗旋转螺杆构建体的钛DHS的EQV(200.94MPa)。短CMN构建体中的近端碎片位移约为0.13mm，最伟大的建筑。在短CMN中，方头螺钉的螺钉切口风险是DHSs和带有防旋转螺钉结构的DHSs的3.1-5.8倍。
结论：钛DHS与防旋转螺钉结合提供了较低的碎片位移，压力，扭转载荷下股骨头的应变能密度比其他固定方式高。CMNs治疗股骨颈股骨颈骨折可能会增加方头螺钉切口的风险。
方法：生物力学研究模型使用三种固定方法：DHS，带有防旋转螺钉的国土安全部，一个简短的CMN。使用有限元分析来模拟髋部旋转，其中肌肉力量与施加到股骨的腿部摆动有关。固定时的等效vonMises应力(EQV)，碎片移位，和近端松质骨的应变能密度监测固定稳定性。
结果:短CMN构建体的EQV(304.63MPa)与钛DHS构建体的EQV(293.39MPa)相当,并且大于具有抗旋转螺杆构建体的钛DHS的EQV(200.94MPa)。短CMN构建体中的近端碎片位移约为0.13mm，最伟大的建筑。在短CMN中，方头螺钉的螺钉切口风险是DHSs和带有防旋转螺钉结构的DHSs的3.1-5.8倍。
结论：钛DHS与防旋转螺钉结合提供了较低的碎片位移，压力，扭转载荷下股骨头的应变能密度比其他固定方式高。CMNs治疗股骨颈股骨颈骨折可能会增加方头螺钉切口的风险。
