Intervertebral Motion After Incremental Damage to the Posterior Structures of the Cervical Spine

In Brief Study Design. Compare intervertebral motion after incremental damage to posterior cervical structures in whole cadavers to motion in asymptomatic subjects. Objective. Determine if damage to the posterior structures of the cervical spine can be detected by quantitative analysis of flexion-extension radiographs. Summary of Background Data. Simulated damage to the posterior structures of the cervical spine can change intervertebral motion, if intervertebral motion before damage is known. It is not known if intervertebral motion measured from flexion-extension radiographs can be used to detect damage to the posterior structures if motion before damage is not known. Methods. Incremental injury to posterior ligaments and facet joints was simulated in 12 whole cadavers. Intervertebral motion was measured from flexion-extension images using validated and clinically applicable software. Measurements were compared to previously published measurements for asymptomatic subjects. Results. Extensive damage could be simulated in all the cervical spines without intervertebral motion exceeding the 95% confidence limits for asymptomatic subjects. After sectioning all posterior ligaments, destroying both facet joints, and then sectioning the posterior longitudinal ligaments, intervertebral motion exceeded the 95% confidence intervals in 69% of the cadavers. Intervertebral shear decreased with incremental damage to posterior structures. Conclusions. Radiographic assessment of the cervical spine may not be sufficient to exclude even extensive damage to the posterior structures of the cervical spine. Incremental damage to the posterior structures of the cervical spine was simulated in a whole cadaver model. The posterior structures of the cervical spine had to be almost completely destroyed before intervertebral motion during maximum flexion and extension was more than the 95% confidence intervals that have been published for asymptomatic subjects.