自制股骨头内撑器治疗早期股骨头坏死的有限元分析

Finite element analysis for self-made femoral head brace device in the treatment of early femoral head necrosis

背景:髓芯减压治疗早期成人股骨头缺血坏死得到大多数学者们的认同,但术后股骨头容易塌陷,如何防止塌陷仍是目前需要解决的问题。目的:应用有限元法对股骨头内撑器治疗成人早期股骨头缺血性坏死进行生物力学分析,为治疗成人早期股骨头坏死提供生物力学依据。方法:取青壮年意外死亡新鲜股骨标本1具,大体观无畸形、骨折、经X射线证实,无肿瘤、骨质疏松等病理性骨质病变。应用螺旋CT分别对正常股骨头颈、髓芯减压股骨头颈、内撑器置入并植骨股骨头颈由近端向远端垂直纵轴进行扫描,并获得图像数据。将扫描数据导入Mimics软件,应用有限元法对3种模型股骨头颈部进行生物力学分析。结果与结论:(1)正常股骨头受压后应力分散并向下传导,压应力集中在股骨距、张应力集中于转子窝;(2)髓芯减压后股骨头部负重区应力集中,位移大,应变增大;(3)内撑器置入并植骨后应力变化与正常股骨头部应力相近;(4)结果提示,髓芯减压后股骨头负重区应力集中,应变增大,负重区容易塌陷;内撑器置入并植骨模型应力分散,承载负荷大于正常股头颈部,且应变减小,符合正常股骨头颈部的力学性能。

BACKGROUND:Core decompression for early adult ischemic necrosis of femoral head gets the identity of most scholars,but the postoperative femoral head easily experiences collapse.How to prevent collapse is still a problem to be solved currently.OBJECTIVE:To perform biomechanical analysis of femoral head ischemic necrosis by using the finite element method and to provide biomechanical basis for the treatment of early adult femoral head necrosis.METHODS:One fresh femur specimen died of accidental death in youth and young adults was obtained,and no deformity or fracture was found.X-ray confirmed that it did not have tumor or osteoporosis.Spiral CT was used to scan normal femoral head and neck,pulp core decompression of femoral head and neck,brace device placement and bone-graft of femoral head and neck for acquiring image data from the proximal to distal vertical longitudinal axis.Scanning data were input in the Mimics software.Finite element method was utilized for biomechanical analysis of femoral head and neck of three models.RESULTS AND CONCLUSION:(1)The stress dispersal and downward conduction of normal femoral head was concentrated in the shaft of the femur and the tensile stress was concentrated in the rotor socket.(2)After pulp core decompression,the stress concentration,displacement and strain increased in the weight-bearing area of femoral head.(3)The stress of the internal bracing was similar to that of normal femoral head.(4)The stress of weight bearing area of femoral head is concentrated,and the strain is increased,so that weight bearing area is easy to collapse after pulp core decompression.The more stress distribution,more bearing load and less strain of implant and bone graft model,are conformed to the normal mechanical properties of the normal femoral head and neck.