复杂不稳定型股骨粗隆间骨折3种固定系统的生物力学研究

目的 针对复杂不稳定型股骨粗隆间骨折，比较动力髋螺钉（dynamic hip screw, DHS）、股骨近端防旋髓内钉（proximal femoral nail antirotation, PFNA）和股骨近端内固定支架（proximal femoral internal-fixator, PFI）有效性及力学差异。方法 取18具Synbone股骨近端人工骨模型，制成复杂不稳定型股骨粗隆间骨折模型（Evans-Jensen III型），分别以DHS、PFNA和PFI固定，用实验应力分析方法，比较3种固定方式的差异及优劣。结果 在压缩载荷300、600、1 200 N下，DHS固定后骨折两端的位移均最大，与PFI、PFNA相比均有显著性差异（P＜0.05），PFI与PFNA骨折两端的位移均无显著性差异（P＞0.05）。在扭转载荷300、600、1 200 N下，DHS及PFNA固定后骨折两端的位移均最大，两者间无显著性差异（P＞0.05）；PFI与DHS、PFNA相比均有显著性差异（P＜0.05）。结论 在复杂不稳定型股骨粗隆间骨折中，PFI系统的抗压缩稳定性与PFNA系统接近，但抗扭转稳定性强于PFNA系统；无论是抗压缩稳定性还是抗扭转稳定性方面，DHS固定系统都最小。
Objective To compare the effectiveness and mechanical differences in the dynamic hip screw (DHS), proximal femoral nail antirotation (PFNA), and proximal femoral internal fixator (PFI) for fixing complex unstable proximal intertrochanteric fractures by biomechanical testing. Methods Eighteen Synbones of the proximal femur were made to simulate complex unstable femoral intertrochanteric fracture models (Evans-Jensen TypeⅢ), which were fixed by DHS, PFNA, and PFI, respectively. The models were tested using a biomechanical testing machine, in order to compare their differences and advantages for fixing fractures. Results Under the compressive loads of 300, 600, and 1 200 N, the fracture displacement of the DHS was the maximum, with a significant difference compared with PFNA and PFI (P<0.05). There were no significant differences between PFNA and PFI (P>0.05). Under torsional loads of 300, 600, and 1 200 N, the torsional displacements of DHS and PFNA at the fracture ends were the maximum, with no significant difference (P>0.05). There were significant differences between PFI and PFNA as well as PFI and DHS (P<0.05). Conclusions For complex unstable proximal intertrochanteric fractures, the stability of the compression resistance of the PFI system is similar to that of the PFNA system. However, the torsional resistance of PFI is stronger than that of PFNA. The DHS system shows the least resistance with respect to compression and torsion.