Burst fractures of the thoracolumbar spine: changes of the spinal canal during operative treatment and follow-up.

Although multiple studies have concluded operative decompression of a traumatically narrowed spinal canal is not indicated because of spontaneous remodeling, instrumental decompression is frequently used as part of the operative treatment of spinal fractures. To investigate the process of remodeling, we studied the diameter of the spinal canal in 95 patients with burst fractures at the thoracolumbar junction (T9-L2). To measure and compare the spinal canal's diameter we used either computed tomography (CT) scans or radiographs, made preoperatively, postoperatively, after 9 months and after 24 months. In lateral plain radiographs we found that the initial percentage of cases with bony canal narrowing preoperatively of 76.5 was reduced to 18.4% postoperatively, to 8.2% at 9 months, and to 2.4% at 24 months. In CT scans in a selection of patients, the mean residual diameter of the spinal canal was 53% preoperatively and 78% at 24 months. The posterior segmental height increases during operation and decreases in the respective periods after operation. So ligamentotaxis can only play a role in the perioperative period. We conclude that a significant spontaneous remodeling of the spinal canal follows the initial surgical reduction. Two years after operation, bony narrowing of the spinal canal is only recognizable in 2.4% of the patients on plain lateral radiographs. The remodeling of the spinal canal can be seen on plain radiographs, although not as accurately as on CT scans.

Thoracolumbar spinal fractures: segmental range of motion after dorsal spondylodesis in 82 patients: a prospective study.

In order to study the effect of dorsal spondylodesis on intervertebral movement in patients treated for thoracolumbar fractures, we measured the sagittal range of motion (ROM) in the segments above and below the fractured vertebral body 2 years after operation. Between 1991 and 1996, 82 consecutive patients with a fracture of the thoracolumbar spine (T12, L1, L2 and L3) were treated operatively with open reduction and stabilisation using an internal fixator, combined with transpedicular cancellous bone graft and dorsal spondylodesis. Eighteen T12, 42 L1, 17 L2 and 5 L3 fractures were included. The range of motion of two segments above and two segments below fracture level was measured. This was done on plain flexion and extension radiographs. The data were compared to normal values and to the zero distribution with the Kolmogorov-Smimov test. At all fracture levels the ROM of the segment adjacent to the disturbed endplate of the fractured body was zero (K-S test). All other evaluated segments showed significant loss of ROM (P<0.05) compared to normal values, except segment L1-L2 in L3 fractures (P=0.058). Dorsal spondylodesis at the level of the disturbed endplate in thoracolumbar spinal fractures leads to immobility in this segment, measured on flexion-extension radiographs 2 years after primary operative treatment. More than 50% loss of motion in the two adjacent levels is equivalent to complete loss of ROM in a second segment.