A finite element analysis of six-segment classification of femur intertrochanteric fracture / 中华创伤骨科杂志

ABSTRACT

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.