股骨转子间六部分骨折分型产生机制的有限元分析

A finite element analysis of six-segment classification of femur intertrochanteric fracture

目的 建立股骨近段三维有限元模型,探讨股骨转子间六部分骨折分型的产生机制及临床意义.方法 应用64层螺旋CT对l例60岁正常男性志愿者左股骨近段进行扫描,所得图像以.jPg格式保存,并导入Photoshop 7.0软件进行三维模型绘制,再将所得三维图像运用Super 93软件建立股骨近段三维有限元模型,划分节点764个,单元531个（密质骨306个、松质骨225个）.运用该模型模拟人摔倒过程中髋关节内收、外展、内收内旋、外展外旋及髋关节内收内旋同时臀中肌、梨状肌、髂腰肌剧烈收缩状况下股骨转子间的应力分布情况. 结果 单纯髋关节内收时,应力主要分布于外侧骨皮质部并向转子间区扩散（二部分骨折）.单纯髋关节外展时,应力主要分布于内侧骨皮质部并向转子间区扩散（二部分骨折）.髋关节内收内旋或外展外旋时,应力均在大转子及转子部的前侧壁、后侧壁较为集中,并同时向内、外侧骨皮质及转子间区扩散（三、四部分骨折）.髋关节内收内旋同时梨状肌、臀中肌、髂腰肌剧烈收缩时,应力在大转子、小转子及转子部的前侧壁及后侧壁较为集中,并同时向内、外侧骨皮质及转子间区扩散（五、六部分骨折）. 结论 股骨转子间六部分骨折分型符合人摔倒时转子部所受的复杂应力情况,结合CT三维重建,较以往的分型更加直观,并可根据不同分型选择手术方式.

Objective To explore the mechanism of six-segment classification of femur intertrochanteric fracture in a three-dimensional finite element model of upper thigh-bone and its clinical relevance.Methods The left upper thigh-bone of a normal male volunteer of 60 years old was scanned using 64-slice CT.After the images were stored in the format of JPG,they were input into photoshop 7.0 for three-dimensional creation.The three-dimensional images were used to make a three-dimensional finite element model of upper thigh-bone using software Super 93.The model consisted of 764 nodes and 531 units （including 306 compact bone units and 225 cancellous bone units）.In this model,the stress distribution at the trochanter during human tumbling was analyzed by imitating adduction,abduction,adduction-intemal rotation and abduction-external rotation of the hip,as well as intense muscular contraction of gluteus medius,piriformis and iliopsoas during adduction-internal rotation of the hip.Results Analysis of stress nephogram showed that the stress was distributed mainly at the exterior cortical bone and spread to the inter-trochanteric part in simple hip adduction （two-part fracture） and distributed mainly at the interior cortical bone and spread to the inter-trochanteric part in simple hip abduction （two-part fracture）.In adduction-internal rotation or abduction-external rotation of the hip,the stress was focused on the anterior and posterior walls of the greater trochanter and trochanteric part and spread to the exterior and interior cortical bone and the inter-trochanteric part （three-or four-part fracture）.During intense muscular contraction of gluteus medius,piriformis and iliopsoas during adduction-internal rotation of the hip,the stress was focused on the anterior and posterior walls of the greater trochanter,lesser trochanter and trochanteric part and spread to the exterior and interior cortical bone and the inter-trochanteric part （five-or six-part fracture）.Conclusions The six-segment classification of femur intertrochanteric fracture explains complex stress distributions after human falling.When combined with three-dimensional CT reconstruction,it is more intuitive than other classifications so that it can provide more definite surgical advice for different types of fracture.