Biomechanical Evaluation of Subaxial Lateral Mass Prothesis: A Finite Element Analysis Study

Abstract Background: Pathologies of a lateral masses due to trauma, tumors, and surgery, could lead to bone destruction and biomechanical changes of the cervical spine. Their treatment includes lesion resection and internal fixation. However, the resulting bone defect of a lateral mass is often neglected, resulting in difficulty in bone fusion. Therefore, we designed a subaxial lateral mass prosthesis to achieve lateral mass joint fusion by implanting the prosthesis along with granular bone.Objective: To evaluate the role of a new subaxial lateral mass prosthesis in load sharing using finite element analysis.Methods: Cervical computed tomography was performed on a healthy volunteer. Five finite element models (intact, lateral mass resection, screw-rod fixation, prosthesis implantation, and prosthesis fusion groups) were compared in terms of the range of motion (ROM), prosthesis von Mises stress, and screw-rod von Mises stress during flexion, extension, lateral bending, and rotation. Results: After lateral mass resection, the ROM of the model increased significantly. The ROM was significantly reduced after fixation with screws and rods. Screw-rod fixation combined with prosthesis implantation further reduced the ROM, especially during left and right bending. After bone fusion in the prosthesis, the ROM can also be reduced slightly. The von Mises stress of the bilateral screws and rods was significantly decreased after prosthesis implantation. The von Mises stress of the prosthesis was further decreased during the right bending after bone fusion was achieved.Conclusion: Subaxial lateral mass prosthesis can help to restore the stability of the cervical spine after lateral mass resection and can reduce the stress on the bilateral screws and rods. Reconstruction of a lateral mass is more consistent with the mechanical transmission of the three-column spine and contributes to interbody fusion of the lateral mass joint.