EFFECTS OF ANTERIOR VERTEBRAL GRAFTING ON THE TRAUMATIZED LUMBAR SPINE AFTER PEDICLE SCREW-PLATE FIXATION

This study was conducted to determine the effects of corpectomy and an terior strut grafting on the biomechanics of traumatized lumbar spine after pedicle screw-plate fixation. Eight lumbar spines were loaded un til fracture (initial cycle) and then reloaded to the same deformation (injury cycle). After transpedicular fixation, spines were again load ed (fixation cycle). Partial corpectomy of the fractured body and ante rior strut grafting were accomplished; the spine reloaded (strut cycle ). Spine angles were measured and biomechanical strength and kinematic parameters analyzed. Load-deformation relationships were similar for fixation and strut cycles until maximum load; at failure, loads were h igher for the former (P < 0.05), however. Alignment was improved by st abilization or stabilization plus anterior grafting (P < 0.05). Verteb ral height was best maintained by grafting as an adjunct to pedicle fi xation (P < 0.05). Kinematics were largely unaffected by grafting, exc ept for reduced motion at the posterior vertebral targets between the fixated levels (P < 0.05). The strength of the fixated spine is relati vely unchanged by corpectomy and anterior grafting; alignment may be i mproved in the latter group.