Experimental study on properties of stress-relaxation of the middle and lower cervical spine / 中华创伤骨科杂志

ABSTRACT

Objective To study the properties of stress relaxation of the middle and lower cervical vertebrae, and to evaluate the effects of laminotomy and anterior diskectomy and spinal fusion (ASF) on the properties . Methods The dynamic responses of stress relaxation of six intact and post operative fresh human cadaveric cervical vertebrae were measured in vitro. Results Under the condition of the constant strain, the functional equations and the curves of stress relaxation of the six intact and post operative fresh human cadaveric cervical vertebrae were obtained. The Gex(t)(the ratio of the ensuing instant stress to the original stress) of the post operative ones was significantly bigger than that of the intact ones; The Gex(t) of the laminotomic ones was significantly bigger than that of the ones having undergone the anterior discectomy and spinal fusion(ASF). Conclusion Either in flexion or in extension, cervical vertebrae have the similar behaviors of stress relaxation. The laminotomy and anterior discectomy and spinal fusion (ASF) all reduce the stress relaxation effect of the cervical vertebrae, but ASF is more significant.