股骨髁部不稳定骨折四种内固定方法的生物力学

目的:对治疗股骨髁部不稳定骨折常用的4种内固定方式进行生物力学评价,为临床治疗提供理论依据。方法:采集24根尸体股骨,模拟股骨髁T形骨折,分组用股骨逆行交锁髓内钉、股骨髁解剖钢板(远端为3孔)、动力髁螺钉和95°角钢板固定,进行轴向压缩试验和轴向扭转试验,测量标本的应变、纵向压缩位移、水平分离位移和扭转角度。结果:发现在同等载荷条件下,中心型逆行交锁髓内钉的强度和刚度优于侧方钢板螺钉系统(P<0.01);动力髁螺钉和逆行交锁髓内钉的抗扭强度和刚度优于95°角钢板和股骨髁解剖钢板(P<0.01)。从应力遮挡实验来看,逆行交锁髓内钉和动力髁螺钉的应力遮挡率大。结论:采用逆行交锁髓内钉和动力髁螺钉固定股骨髁T形骨折,具有良好的生物力学性能,但应注意它的应力遮挡效应,骨折愈合后及时取出内固定。

A comparative biomechanical study of four internal fixation methods for unstable fracture of femoral condyle

Objective: To evaluate the biomechanical performance of four internal fixation methods for unstable fracture of femoral condyle and to provide the scientific base for clinical application. Methods: Twenty-four femoral specimens were divided into four groups randomly. They were made the models of T shaped fracture of femoral condyle (C1 of AO classification), each group was fixed with supracondylar intramedullary interlocking nail (GSHN), anatomical condyle plate, dynamic condyle screw(DCS) and L shaped condyle plate(L-CP). They were compared through axis compress experiment and axis torsion experiment. Results: Under the same load condition, the intensity and the rigidity of the GSHN system was prior to the other three plate-screw fixation system(P < 0.01). In axis torsion experiment, the torsional stiffness of dynamic condyle screw and supracondylar intramedullary interlocking nail was better than L shaped condyle plate and anatomical condyle plate (P < 0.01). The GSHN and DCS had great stress shielding rate. Conclusion: The biomechanical performance of GSHN and DCS is better than the two other internal fixation methods for T shaped fracture of femoral condyle. They should be taken out in time because they have great stress shielding rate.