Abstract
Adjacent level vertebral fractures are common in patients with osteoporotic wedge fractures, but can theoretically be prevented with prophylactic vertebroplasty. Previous tests on prophylactic vertebroplasties have been performed under axial loading, while in vivo changes in spinal alignment likely cause off-axis loads. In this study we determined whether prophylactic vertebroplasty can also reduce the fracture risk under off-axis loads. In a previous study, we tested vertebral bodies that were loaded axially or 20 degrees off-axis representing vertebrae in an unfractured spine or vertebrae adjacent to a wedge fracture, respectively. In the current study, vertebral failure load and stiffness of our previously tested vertebral bodies were compared to those of a new group of vertebral bodies that were filled with bone cement and then loaded 20 degrees off-axis. These vertebral bodies represented adjacent-level vertebrae with prophylactic bone cement filling. Prophylactic augmentation resulted in failure loads that were comparable to those of the 0 degrees group, and 32% greater than the failure loads of the 20 degrees group. The stiffness of the prophylacticly augmented vertebrae was 21% lower than that of the 0 degrees group, but 27% higher than that of the 20 degrees group. We conclude that prophylactic augmentation can decrease the fracture risk in a malaligned, osteoporotic vertebra. Whether this is enough to actually prevent additional vertebral fractures in vivo remains subject of further study.
