Selection of short- or long-segment posterior fixation for treatment of unstable thoracolumbar fractures

Abstract

Objective To discuss the selection of short- or long-segment posterior fixation for treatment of unstable thoracolumbar fractures. Methods A total 134 patients with thoracolumbar fractures treated with pedicle instrument fixation from January 2005 to December 2008 were studied retrospectively. According to AO fracture classification, there were 70 patients with type A fractures, 37 with type B and 27 with type C. The patients were divided into two groups according to the number of instrumented levels; short-segment posterior fixation (SSPF) group (four screws; one vertebral body above or below the fractured vertebrae) and long-segment posterior fixation (LSPF) group (eight screws; two vertebral bodies above or below the fractured vertebrae). Clinical outcomes and radiological parameters (superior-inferior endplate angle, vertebral body angle, displacement of vertebral body) were compared according to AO fracture classification. Results All type A fractures were treated with SSPF, mean superior-inferior endplate angle changed from preoperative 21.3° to postoperative 8.5° and 11.1° at final follow up. There was no statistical difference in the correction of Cobb angle for type B fractures in SSPF group (26 patients) and LSPF group (11 patients), while the correction loss of vertebral body angle was 3. 64° in SSPF group and 1.09° in LSPF group, with statistical difference (P < 0. 05). There was no statistical difference in the correction of Cobb angle for type C fractures in SSPF group (7 patients) and in LSPF group (20 patients), but the correction loss of vertebral body angle was 3.6° in SSPF group and 0. 8° in LSPF group, with statistical difference (P < 0. 05). There was no statistical difference in vertebral displacement correction. Conclusions Most types A and Bl fractures should be treated with SSPF; most types B2, B3 and C fractures should be treated with LSPF. Key words: Spinal fractures; Thoracic vertebrae; Lumbar vertebrae; Fracture fixation, internal; Fracture classification