In Vitro Biomechanics of Human Cadaveric Cervical Spines With Mature Fusion.

ABSTRACT Background This study sought to compare index and adjacent-level biomechanics of cadaveric specimens with mature fusion versus normal spines in intact and acutely fused conditions. Methods Eight human cadaveric cervical spines with mature fusion across 1 to 3 levels were studied. Intervertebral angular range of motion (ROM) was determined at fused and adjacent levels during pure moments inducing flexion-extension (FE), lateral bending (LB), and axial rotation (AR). Mature fusion data were compared to data from normal spine specimens tested intact and then with a 1-level anterior plate/graft (fresh fixation). Bone qualities were compared using dual-energy x-ray absorptiometry. Results Mean bone mineral density was significantly greater in mature fusion spines (0.632 ± 0.239 g/cm2) than in normal spines (0.489 ± 0.195 g/cm2) (P Conclusion Cervical spine segments with mature fusion have higher bone mass, are less flexible than freshly fixed spines, and have reduced mobility at adjacent levels.