Using CT scans of 112 consecutive patients with thoracolumbar burst fractures, we investigated the relationship between traumatic spinal canal stenosis and neurologic deficits. We calculated the stenotic ratios of the area occupied by the retropulsed bony fragments to the estimated area of the original spinal canal. We also examined the shape of the narrowed canal and the disruption of spinal elements. Burst fractures having the following ratios are at significant risk of neurologic involvement: at T11 to T12 with 35% more, at L1 with 45% or more, and at L2 and below with 55% or more.