Assessment of the posterior ligamentous complex following acute cervical spine trauma.

BACKGROUND: Magnetic resonance imaging is commonly used to assess the integrity of the posterior ligamentous complex following cervical trauma, but its accuracy and reliability have not been documented, to our knowledge. The purpose of this study was to determine the diagnostic accuracy of magnetic resonance imaging in detecting injury to specific components of the posterior ligamentous complex of the cervical spine.
METHODS: Patients with an acute cervical spine injury that required posterior surgical treatment were prospectively studied. The six components of the posterior ligamentous complex were characterized as intact, incompletely disrupted, or disrupted on preoperative magnetic resonance imaging studies by a radiologist and intraoperatively by two surgeons. Correlation between the magnetic resonance imaging and intraoperative findings was determined. The percent agreement, sensitivity, specificity, negative predictive value, and positive predictive value of magnetic resonance imaging as a tool for characterizing the integrity of the posterior ligamentous complex were calculated.
RESULTS: Forty-seven consecutive patients with a total of seventy levels of injury were studied. Overall, there was moderate agreement between the magnetic resonance imaging and intraoperative findings for the supraspinous and interspinous ligaments (kappa scores of 0.46 and 0.43, respectively) and fair agreement between those for the ligamentum flavum, left and right facet capsules, and cervical fascia (kappa scores of 0.32, 0.31, 0.26, and 0.39, respectively). The sensitivity of the magnetic resonance imaging was greatest for the cervical fascia (100%) and the lowest for the facet capsules (80%). Specificity ranged from 56% (for the facet capsules) to 67% (for the interspinous ligament). The positive predictive value ranged from 42% (for the cervical fascia) to 82% (for the interspinous ligament).
CONCLUSIONS: Magnetic resonance imaging is sensitive for the evaluation of injury to the posterior ligamentous complex in the setting of acute cervical trauma. However, it has a lower positive predictive value and specificity, suggesting that injury to the posterior ligamentous complex may be "over-read" on magnetic resonance images. If magnetic resonance imaging is used in isolation to guide treatment, the high rate of false-positive findings may lead to unnecessary surgery. Other factors, including the morphology of the injury and the neurological status, should be considered as well when devising a treatment plan.