The significance of thoracolumbar spinal canal size in spinal cord injury patients

Study Design: A prospective, consecutive case series. Objectives: To determine the relation between spinal canal dimensions and Injury Severity Score and their association with neurologic sequelae after thoracolumbar junction burst fracture. Summary of Background Data: There is a relation in the cervical spine between spinal canal dimension and its association with neurologic sequelae after trauma. A similar relation at the thoracolumbar junction has not been conclusively established. Methods: Forty-three patients with thoracolumbar junction burst fractures (T12-L2),13 with and 30 without neurologic deficit, were included. Computed tomographic scans were used to measure the sagittal and transverse diameters and the surface area of the spinal canal at the level of injury, as well as one level above and one level below the fracture level. Injury severity score was calculated for both groups. Statistical analysis comparing those with a neurologic deficit to those without was performed by Student's t test. Results: The ratio of sagittal-to-transverse diameter at the level of injury was significantly smaller in patients with a neurologic deficit than in those without a neurologic deficit (P < 0.05). The mean transverse diameter at the level of injury was significantly larger in patients with neurologic deficit than in the neurologically intact patients (P < 0.05). The surface area of the canal at the level below the injury was significantly larger in the patients with a neurologic deficit than in those without a deficit (P < 0.05). Patients with a neurologic deficit had a statistically higher injury Severity Score when admitted than those without a neurologic deficit (P < 0.0001), although the difference became insignificant after the neurologic component of the scoring system was eliminated. Conclusion: There are no anatomic factors at the thoracolumbar junction that predispose to neurologic injury after burst fracture. The shape of the canal after injury, however, as determined by the sagittal-to-transverse diameter ratio, was predictive of neurologic deficit.