Radiographic assessment and quantitative motion analysis of the cervical spine after serial sectioning of the anterior ligamentous structures.

STUDY DESIGN

Cadaveric study of a diagnostic test for cervical spine instability.

OBJECTIVE

Determine if flexion-extension (FE) radiographs can be used to detect incremental damage to anterior cervical structures.

SUMMARY OF BACKGROUND DATA

Prior studies have shown that damage to cervical structures can alter motion between vertebrae, and FE radiographs are sometimes used to detect this damage. However, no study has determined if FE radiographs are sensitive and specific for acute injury.

METHODS

FE radiographs were taken of the intact neck and after each incremental increase in damage to the anterior structures. Intervertebral motion was quantified using previously validated methods. The sensitivity and specificity of intervertebral motion measurements were assessed.

RESULTS

Motion within the intact spines was within normal ranges. Although intervertebral rotation changed significantly after certain anterior structures were damaged, rotation frequently remained within normal ranges, even after extensive damage. A center of rotation that was posterior to the 95% confidence interval for normal motion was 100% sensitive and specific for damage to the anterior structures of the spine.

CONCLUSIONS

The results suggest that extensive damage to the anterior cervical spine could be missed if instability assessment was based on intervertebral rotation or displacements measured from FE radiographs. In contrast, a center of rotation that was located posterior to normal was both sensitive and specific for damage to anterior structures.