Radiographic parameters for evaluating the neurological spaces in experimental thoracolumbar burst fractures

It is important to know the condition of neural spaces during the nonoperat ive treatment of thoracolumbar burst fractures. The goals of the current st udy were to identify the correlation between the degree of deformity of a f ractured vertebra and the encroachment of neural spaces, and to determine h ow the encroachment and the deformity can be improved by the extension post ure simulating the postural reduction. Experimental burst fractures were pr oduced in L1 vertebrae of nine human thoracolumbar spine segments (T11-L3) with neural spaces lined with tiny steel balls. Lateral radiographs were ta ken in neutral and extended posture before and after the trauma. Anterior v ertebral height, posterior vertebral height, vertebral height ratio. verteb ral kyphotic angle, posterior vertebral body angle, and the cross diagonal angle were the geometric parameters used to describe the vertebral deformit y. The canal diameter and superior and inferior intervertebral foramen area s were defined as the neural spaces. All parameters were measured on the sc anned images of radiographs, as seen on the computer screen. Among the vert ebral body parameters, the posterior vertebral height, posterior vertebral body angle, and cross diagonal angle showed significantly higher correlatio ns with the canal encroachment. The extended posture did not improve the ca nal and intervertebral foramen encroachments. The kyphotic deformity (verte bral kyphotic angle and anterior vertebral height) was improved but the def ormity of the vertebral posterior wall (posterior vertebral height and post erior vertebral body angle) was not improved because of the extended postur e.