应用皮质支撑原理固定股骨颈骨折的生物力学研究

Biomechanical study on femoral neck fracture fixation based on cortical screw support theory

目的根据皮质支撑的方法，探讨应用空心螺钉固定股骨颈骨折的生物力学效果。方法选择8具成人防腐股骨标本，用随机数字表法分成两组，每组4具，制成股骨颈骨折的模型。实验侧3枚空心螺钉采用皮质支撑方法固定，对照侧采用非皮质支撑方法固定。两组标本分别进行抗压试验和抗扭转试验。结果在抗压试验中，当压力为600N和800N时，皮质支撑组股骨头的位移分别为（0．677±0．135）mm和（0．907±0．132）mm，非皮质支撑组分别为（0．899±0．160）mm和（1．202±0．152）mm（P〈0．05）。内固定失败时，皮质支撑组承受的最大载荷为（2782±228）N，非皮质支撑组为（1950±281）N（P〈0．01）。在抗扭转试验中，扭转4。和6。时，皮质支撑组的扭矩分别为（10．406±1．515）Nm和（15．328±1．471）Nm，非皮质支撑组的扭矩分别为（6．628±1．163）Nm和（9．072±1．570）Nm，两者比较差异有统计学意义（P〈0．01）。内固定失败时，皮质支撑组和非皮质支撑组的最大扭矩分别为（25．437±5．213）Nm和（13．235±3．012）Nm（P〈0．01）。结论根据皮质支撑理论使用空心螺钉固定股骨颈骨折能明显提高内固定的抗压和抗旋转能力。

Objective To evaluate the biomeehanical effect of conical screw support technique in fixation of the femoral neck fractures. Methods The models of subcapital femoral neck fracture were made in eight matched pairs of embamled cadaver femurs and devided into experiment group and control group （four pairs per group）. The side of experiment group was fixed using three cannulated compression screws with conical screw support and that of control group with conventional screw placement. The specimens in two groups were tested in aspects of torsion and axial loading. Results In axial load test at load of 600 N and 800 N, the displacements in cortical screw support group were （0. 677 ± 0.135 ） mm and （0. 907 ± 0. 132 ） mm respectively, while those of femoral head in conventional screw placement group were （0.899 ±0. 160） mm and （ 1. 202 ±0. 152） mm respectively （P 〈0.05）. There was significant difference between the two groups （ P 〈 0.05 ）. The maximal vertical loading for failure of the fixa- tion was （2 782 ± 228） N in cortical screw support group and （1 950 ± 281 ） N in conventional screw placement group （P 〈 0.01 ）. In torsibility test at 4~ and 6~ torsibility, the torque-moments of cortical screw support group were （ 10.406 ± 1. 515） Nm and （ 15. 328 ± 1. 471 ） Nm respectively and those of conventional screw placement group （6. 628±1. 163） Nm and （9. 072 ± 1. 570） Nm respectively, with statistical difference between two groups （P 〈 0.01 ）. The maximal torque-moment for failure of the fixation was （25.437 ±5. 213） Nm in cortical screw support group and （13. 235 ±3. 012） Nm in conventional screw placement group （ P 〈 0.01 ）. Conclusion Fixation of femoral neck fractures by using cortical screw support can significantly enhance anti-torsion and anti-compression of internal fixation.