Osteoporosis significantly increases the risk of bone fracture. Falls are the leading cause of osteoporotic fracture among elderly people. The incidence of low-energy acetabular fracture among the elderly population has been increasing in developed countries in recent decades. Lowenergy acetabular fractures mostly happen due to falling from a standing height. While the mechanism of proximal femur fracture due to low-energy falls has been investigated widely owing to higher incidence and the associated morbidities and mortalities, the biomechanical mechanism responsible for acetabular fracture has remained underexplored. Through developing comprehensive finite element models as a reliable and cost-effective method of study, this thesis aims to evaluate the effects of various biomechanical factors contributing to the occurrence, severity, and type of acetabular fracture during low-energy sideways falls.
The finite element models were based on abdominal computed tomography (CT) images of a median male without acetabular fracture history, retrieved from a large clinical dataset. While the bony parts and trochanteric soft tissue were reconstructed directly from the CT images, cartilages and ligaments were added manually according to anatomy and literature. The material models able to simulate the behavior of tissues during the impact loading condition were considered. Initial/ boundary conditions, loads, contacts, interactions, and controlling parameters were applied according to the literature. By varying the corresponding variables in the model, the effects of body configuration, impact velocity, flooring material, trochanteric soft tissue stiffness, and bone loss on the risk the acetabular fracture were investigated.
Results of the current study showed that the effects of body configuration, impact velocity, and bone loss on the risk of acetabular fracture are substantial. However, the effects of flooring material and trochanteric soft tissue stiffness remained marginal. This study suggests a horizontal trunk and femur at the impact, the impact velocity higher than 3.17 m/s, and severe bone loss increase the risk of acetabular fracture considerably.
In conclusion, it appears that among studied biomechanical factors, those related to the bone quality and kinematics of the fall have a significant effect on the risk of acetabular fracture.