Title

In Vitro Biomechanics of Human Cadaveric Cervical Spines With Mature Fusion

Document Type

Article

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/cm) than in normal spines (0.489 ± 0.195 g/cm) ( < .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 ( .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%, < .001; LB: -42%, < .001; AR: -49%, .001), followed by 1 level above fusion (FE: -23%, .04; LB: -22%, .07; AR: -28%, .02) and 2 levels above fusion (FE: -20%, .08; LB: -18%, .11; AR: -31%, .009). Mature fusion reduced the magnitude of coupled LB during AR at C6-7 and C7-T1 ( .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.

Keywords

adjacent segment, bone mass, cervical, mature fusion

Publication Date

10-1-2021

Publication Title

International journal of spine surgery

ISSN

2211-4599

Volume

15

Issue

5

First Page

890

Last Page

898

PubMed ID

34551927

Digital Object Identifier (DOI)

10.14444/8114

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