Multi-component Finite Element Analysis of Low-Energy Acetabular Fracture. Computational Study of Pelvic Girdle Fracture Mechanism

A Ph.D. thesis performed at the University of Oulu showed that a well-defined CT-based finite element model can be used to assess the biomechanical risk factors of low-energy acetabular fracture. The study shows that the developed finite element models can provide explanations for previous clinical findings and predict the prevalent types of acetabular fracture among the elderly population. Indeed, this study also shows that fall conditions, including impact velocity, and quality of bone are the most important factors in the occurrence, severity, and type of acetabular fracture.
The thesis by M.Sc. Shahab Khakpour was carried out at the University of Oulu in collaboration with the University of Eastern Finland. The comprehensive finite element models were based on abdominal computed tomography (CT) images, retrieved from a clinical dataset collected by Oulu University Hospital. By varying the corresponding variables in the model, the effects of body configuration, impact velocity, flooring material, trochanteric soft tissue stiffness, and change in the mechanical properties of bone caused by osteoporosis progression on the risk and type of acetabular fracture were investigated. The study was funded by the EU H2020 MSCA COFUND.
“Whereas the risk of the hip fracture is higher during a posterolateral fall, the lateral fall is associated with an increased risk of acetabular fracture. Also, impact velocity has a substantial effect on the acetabular fracture, whereas the effects of flooring material and stiffness of the trochanteric soft tissue are only marginal. Moreover, the reductions in the mechanical properties of bone during the progressed stage of osteoporosis lead to the change of acetabular fracture type to be more complicated”, says Khakpour.
Osteoporosis significantly increases the risk of bone fracture, and falls are the leading cause of osteoporotic fracture among elderly people. In recent decades, while the incidence of low-energy hip fracture has been declined, the incidence of acetabular fracture has increased among the elderly population in developed countries. This change in the trend of fractures has attracted more attention to low-energy acetabular fractures. According to this study, 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.
The outcome of the current research could be considered in the design of preventive measures such as training of elderly individuals for a safe landing. Also, the results of this study may be used by professionals involved in the prevention, management, and rehabilitation of acetabular fractures.