ABSTRACT
Using pedicle-screw fixation for the management of spinal fractures in the dorsolumbar junction is widely used. Despite the proper insertion of the pedicle screws, progressive kyphotic deformity may develop post-operatively. Study of different factors related to pedicle-screw fixation in cases with dorsolumbar spinal fractures trying to find out the underlying causes of progressive kyphotic deformity after fixation. This retrospective study includes 52 patients with traumatic fractures of the dorsolumbar junction. All cases were managed by pedicle screw fixation and decompressive laminectomy. Two-level fixation [one above and one below the fractured vertebra] was done in 41 patients, 3 level-fixation in 8 patients, and 4-level fixation in 3 patients. Mean follow up period was 28 months [range from 12-39 months]. Fifteen cases developed post-operative progressive kyphotic deformity. Four of these 15 patients had malposition of pedicle screws and were excluded from the study. The other 11 patients [group A] had two-level fixation and had proper position of the screws as documented by CT scan. Patients in group A were compared to the group of patients who were also operated by two-level fixation but they did not develop postoperative progressive kyphosis [group B, n = 26]. Comparison included number of spinal columns fractured, disruption of facet joints, percentage reduction in the height of the anterior border of vertebral body by the fracture, presence of vertebral body fracture in the coronal plan dividing the body into anterior and posterior segments, presence of anterior dislocation or translation, degree of canal compromise, and presence of associated fracture in the vertebral body adjacent to the injured vertebra. The remaining 11 patients [group C] had 3 or 4 level fixation and did not develop this progressive post-operative kyphosis. Our results showed that the incidence of the following findings were significantly higher in group A than in group B: reduction in the height of the anterior border of vertebral body of 50% or more [82% and -15% respectively], body fracture in the coronal plan [73% and 19% respectively], associated adjacent vertebral body fractures [73% and 27%]. No significant difference was observed between the two groups in the other aspects of comparison. The results of this study indicate that the presence of: more than 50% reduction in the anterior body height, body fracture in the coronal plan, and/or associated adjacent body fracture would indicate a higher degree of spinal instability in patients with fractures of the dorsolumbar junction. It also infers that 2-level fixation is not enough to avoid post-operative progressive kyphosis in such patients