Rethinking Preoperative Planning for Spinal Fusion Surgery

Different spinal pathologies require surgical fusion, which involves a segment of the spine being immobilized by placing screws into the vertebrae and interconnecting them with rigid rods. This immobilization allows the spine to fuse naturally over time, alleviating the patient's symptoms by reducing the load on the affected spinal structures. In some instances, the forces on the screws surpass the holding capacity of the bone and the screws loosen, potentially leading to severe clinical complications. In past research projects, we have shown that it is already possible to identify screws at risk of loosening even during pre-operative planning. The integration of data on the vertebral bone's mechanical properties obtained from CT scans, including estimates of the patient's spine loading profile, enables us to create patient-specific mechanical simulations to determine how close to failure the surrounding bone will be during daily life. Identifying screws at risk of loosening would allow surgeons to modify the surgical plan, for example by extending the fusion to include an additional spinal level, adjusting the screw trajectory for better mechanical purchase, or by using bone cement. Given the theoretical potential of this approach to improve patient care by reducing the occurrence of postoperative complications, the current goal is to identify how the procedure could be incorporated into daily clinical practice. To this end, the simulation pipeline is being developed into a userfriendly web-based platform that will allow the surgeon to conduct preoperative planning based on patient-specific biomechanical information.