T1 finite element model of Kümmell's disease shows changes in the vertebral stress distribution

The aims of this study were to develop a finite element model of delayed post-traumatic vertebral osteonecrosis, analyze its effect on the vertebral stress distribution, and provide experimental evidence for osteonecrosis as a risk factor for loss of the vertebral corrective angle. Three-dimensional reconstruction was performed on CT data of the lumbar vertebrae from a 29-year-old male without spinal lesions to develop a normal L1-L3 vertebral model and a model with post-traumatic vertebral osteonecrosis at level L2. Vertebral flexion, extension, and lateral bending were simulated using computer software to determine the stress distribution in the cortical and cancellous bone in the two models and the changes in the vertebral stress distribution with the size and location of the cavity. Simulation of a vertebral cavity tended to increase the Von Mises equivalent stress in the vertebral cancellous bone and reduce the equivalent stress in the cortical bone, while the vertebral equivalent stress displayed a reverse distribution. The equivalent stress was increased in both the cancellous and cortical bones with increasing cavity volume, and the equivalent stress in the cortical bone was always smaller than that in the normal vertebrae. Placing the cavity close to the endplate of the vertebrae tended to cause stress concentrations in the cancellous bone around the endplate. The cancellous bone with post-traumatic osteonecrosis tended to experience greater Von Mises equivalent stress than the normal vertebrae. Differences in the cavity volume and location may result in a more severe abnormal stress distribution.