两种构型空心加压螺钉固定头颈型股骨颈骨折的生物力学效果评估

Evaluation of the biomechanical effect of two geometric configurations of hollow compression screws in fixation for femoral neck fracture

目的:比较两种构型空心加压螺钉固定头颈型股骨颈骨折的股骨标本的生物力学特征,为临床治疗股骨颈骨折提供理论依据。方法:实验于2002-11/2004-03在河北骨科研究所完成。将10根股骨随机分成倒等腰三角形组和正等腰三角形组,每组5根。倒、正等腰三角形构型的3枚空心加压螺钉固定头颈型股骨颈骨折的股骨标本,用生物力学机(长春市实验机研究所产CSS-44020生物力学仪,河北骨科研究所提供)测试、比较两种空间构型抗压、抗扭性能及最大垂直载荷,所得实验数据均用SPSS10.0统计软件进行分析。结果:倒等腰三角形组的抗压、最大垂直载荷性能明显优于正等腰三角形组,具有统计学意义(P<0.05);但两者抗扭转性能无显著性差别(P>0.05)[600和750N垂直载负下,倒等腰三角形组股骨头下沉位移(0.933±0.135)和(1.310±0.217)mm,正等腰三角形组股骨头下沉位移(1.556±0.235)和(1.975±0.250)mm;扭转2°和4°所需力矩,倒等腰三角形组(3.148±0.765)和(6.658±2.021)N·m,正等腰三角形组(2.847±1.130)和(5.392±1.601)N·m;最大垂直载荷倒等腰三角形组(2069.97±200.864)N,正等腰三角形组(1614.57±80.567)N]。结论:对头颈型股骨颈骨折,应用倒等腰三角形构型的空心加压螺钉比正等腰三角形构型的空心加压螺钉固定股骨标本,可获得更好的抗压和体现其最大垂直载荷性能的生物力学效果。

AIM： To compare a biomechanical feature between the efficacies of the two geometric configuration of hollow compression screws in fixation for femoral neck fracture and to offer a theoretical foundation in the treatment of femoral neck fracture. METHODS： The experiment was conducted at the Institute of Department of Orthopaedics of Hebei Province from November 2002 to March 2004. Ten femurs were assigned randomly into inverted isosceles triangle group and upright isosceles triangle group with 5 femurs in each group. The specimen fixed by three hollow compression screws in fixation for femoral neck fracture was measured on the biomechanical machine （CSS-44020 biomeehanical machine was produced by Changchun Tester Institute, and provided by Institute of Department of Orthopaedics of Hebei Province）. The compression strength, torsibility and the maximum vertical loading were compared between the two configurations of screws. The data was processed with statistical software, SPSS 10.0. RESULTS： The compression strength and the maximum vertical loading in the inverted isosceles triangle group were better than those in the upright isusceles triangle group, which had statistical significance （P 〈 0.05）. But there was no significant difference of torsibility between the two groups （P 〉 0.05）[Under 600 and 750 N vertical loading, femoral head sunk （0.933 ±0.135） and （1.310±0.217） mm in the inverted isosceles triangle group. The femoral head sunk （1.556±0.235） and （1.975±0.250） mm in the upright isosceles triangle group. It needed （3.148±0.765） and （6.658 ±2.021 ） N·m in the inverted isosceles triangle group, and （2.847 ± 1. 130） and （5.392±1.601）N·m in the upright isosceles triangle group when distorted 2± and 4±. The maximum vertical loading was （2 069.97±200.864） N in the inverted isosceles triangle group and （ 1 614.57±80.567）N in the upright isosceles triangle group]. CONCLUSION： The inverted isosceles triangle configuration of hollow compression screws should be utilized in treating the femoral head neck fracture as compared with the upright isosceles triangle configuration. It can gain better biomeehanieal effect on compression strength and the maximum vertical loading.