Simulation of hip fracture in sideways fall using a 3D finite element model of pelvis-femur-soft tissue complex with simplified representation of whole body.

Hip fractures due to sideways falls are a worldwide health problem, especially among the elderly population. The objective of this study was to simulate a real life sideways fall leading to hip fracture. To achieve this a computed tomography (CT) scan based three-dimensional (3D) finite element (FE) model of the pelvis-femur complex was developed using a wide range of mechanical properties in the bone of the complex. For impact absorption through large deformation, surrounding soft tissue was also included in the FE model from CT scan data. To incorporate the inertia effect, the whole body was represented by a spring-mass-dashpot system. For trochanteric soft tissue thickness of 14 mm, body weight of 77.47 kg and average hip impact velocity of 3.17 m/s, this detailed FE model could approximately simulate a sideways fall configuration and examine femoral fracture situation. At the contact surface, the peak impact load was 8331 N. In spite of the presence of 14 mm thick trochanteric soft tissue, within the trochanteric zone the most compressive peak principal strain was 3.5% which exceeds ultimate compressive strain. The modeled trochanteric fracture was consistent with clinical findings and with the findings of previous studies. Further, this detailed FE model may be used to find the effect of trochanteric soft tissue thickness variations on peak impact force, peak strain in sideways fall, and to simulate automobile side impact and backward fall situations.