@article {Sawa8114, author = {Anna G. U. Sawa and Bernardo de Andrada Pereira and Nestor G. Rodriguez-Martinez and Phillip M. Reyes and Brian P. Kelly and Neil R. Crawford}, title = {In Vitro Biomechanics of Human Cadaveric Cervical Spines With Mature Fusion}, elocation-id = {8114}, year = {2021}, doi = {10.14444/8114}, publisher = {International Journal of Spine Surgery}, 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 {\textpm} 0.239 g/cm2) than in normal spines (0.489 {\textpm} 0.195 g/cm2) (P \< .001). Mean ROM for levels with mature fusion was 42\% (FE), 42\% (LB), and 29\% (AR) of the mean same-level ROM in freshly fixated specimens (P <= .045). The mean adjacent-level ROM in spines with mature fusion was less than in normal spines (matched levels) in all directions, with the greatest difference 1 level below fusion (FE: -38\%, P \< .001; LB: -42\%, P \< .001; AR: -49\%, P = .001), followed by 1 level above fusion (FE: -23\%, P = .04; LB: -22\%, P = .07; AR: -28\%, P = .02) and 2 levels above fusion (FE: -20\%, P = .08; LB: -18\%, P = .11; AR: -31\%, P = .009). Mature fusion reduced the magnitude of coupled LB during AR at C6-7 and C7-T1 (P <= .03).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.}, issn = {2211-4599}, URL = {https://www.ijssurgery.com/content/early/2021/09/20/8114}, eprint = {https://www.ijssurgery.com/content/early/2021/09/20/8114.full.pdf}, journal = {International Journal of Spine Surgery} }