Sensitivity analysis of biomechanical effect in vertebral body of two different augmenters

Transvertebral Bone Graft and Augmentation (TBGA) has achieved good clinical effects in the treatment of osteoporotic vertebral compression fractures (OVCFs). This study aimed to investigate the postoperatively biomechanical effects of TBGA and compare the biomechanical sensitivity of two different augmenters: a cylindrical enhancement device (CED) and bone cement.

Finite element models of the spine segment T11-L3 were created, including one model based on normal segment and the other three with L1 augmentation for pathological conditions. Three treatments were simulated including CED implant treatment A, CED implant treatment B, and bone cement treatment. The stress distribution and maximum displacement of the four models under different treatments were analyzed. A method of linear fitting of dummy variables was used to analyze the sensitivity of biomechanical parameters to the degree of osteoporosis (DO) and load.

The reduction of stress with increasing DO in augmented and adjacent vertebral bodies under bone cement augmentation was less than that under CED augmentation. The stress of augmented vertebral body and the adjacent vertebral body was most sensitive to extension and rotation loading conditions. As DO increasing, the bone cement augmentation significantly increased the stress level on the upper and lower endplates.

When the degree of osteoporosis increased, CED outperforms bone cement in terms of the stress reduction in augmented vertebral and adjacent vertebral, which could be beneficial for avoiding re-fracture. Using TBGA to treat OVCFs, especially with Plan B method, the condition of the pathological spine is closer to the original status in terms of the sensitivity to stress and the spinal range of motion. The TBGA treatment is sensitive to lateral bending and torsion, therefore patients should be advised to avoid high-risk motions like lateral bending and rotation.