Spinal canal remodeling after stabilization of thoracolumbar burst fractures

ABSTRACT

Bone fragments in the spinal canal after thoracolumbar burst fractures causing spinal canal narrowing is a frequent phenomenon. Efforts to remove such fragments are often considered. The aim of this study was to evaluate the spinal canal remodeling after posterior instrumentation and fusion. 24 patients with unstable thoracolumbar burst fractures were treated in Mansoura Emergency Hospital by transpedicular instrumentation and fusion using autogenous iliac bone graft. There were 16 males and 8 females, their age ranged from 18 to 54 years with a mean age of 34 years. 16 patients had burst fracture at L1 level, 4 patients had fracture of L2, 2 patients had fracture of T12 and another 2 patients had fracture of T11 level. Preoperative CT scan was done routinely for all the patients and sometimes with sagittal reformat to evaluate the pattern of the fracture and the degree of canal compromise. Also detailed neurological evaluation for the patients was achieved and documented. 15 patients had partial neurological insult while 9 patients were neurologically intact. The type of neurological deficit in all patients was scored on the scale of Frankel et al. Spinal canal cross sectional areas [CSA] were measured preoperatively, within 1 week postoperatively and at least 2 years after surgery. The results showed that the preoperative canal encroachment averaged 48.83% [range 30%-72%] of the estimated original area. The 16 patients with neurological deficit had significantly more severe initial canal encroachment [mean 53%] than those who were neurologically intact [mean 41%]. Postoperatively, canal encroachment had decreased to a mean of 33.87% [range 18-55%], at the end of follow-up, canal encroachment was further reduced by resorption of bone fragments to a mean of 12.08% [range 0-32%]. Our results showed statistically significant difference in spinal canal areas postoperatively and at the end of follow-up suggesting effective remodeling of the spinal canal after surgical treatment of thoracolumbar burst fractures with posterior instrumentation and fusion. All patients with neurological deficits improved, and only 4 patients had residual neurological affection. our study shows that canal enlargement during surgery is caused by indirect effects when the spine is distracted and put into lordosis. Remodeling will occur if there is residual narrowing. Acute intervention into the spinal canal, as well as subsequent anterior surgery because of residual bone, should be limited