Abstract
The exact mechanism of remodelling of burst fractures is uncertain. We studied the relationship between epidural pressures and remodelling.
In a prospective, ethically-approved study in 34 patients with burst fractures at the levels T12 to L4, epidural pressure was measured. Four patients were lost to follow-up. In 18 patients the fractures were due to a fall and in 12 to motor vehicle accidents. The mean age was 37 years. All patients were neurologically intact and treated non-operatively. Plain radiographs and CT scans measuring the sagittal plane deformity and mid-sagittal diameter respectively were obtained. Using a fluoroscopically-guided radio-opaque catheter placed at the normal interspace below the burst fracture, epidural pressure was measured at 2 weeks and at 12 months after the injury. The mean canal compromise shown on CT scan at the time of injury and at follow-up was 43% (32% to 83%) and 28% (44% to 100%) respectively. CT volumetric measurements showed a mean improvement of 10% at follow-up (7% to 16%). The epidural pressures recorded at the time of injury and at follow-up were 16.65 mmHg (2.5 to 30.85) and 5.85mmHg (0 to 10.17) respectively. At 1-year follow-up, the Cobbs angle had progressed by a mean of 2.69° (10° to 60°).
The retropulsed burst fracture fragments cause localised constriction of the spinal cord (Venturi effect). Epidural pressure, raised to maintain a constant flow rate across this constriction, has a mechanical effect on the retropulsed fragments, thus promoting remodelling.
Secretary: Dr H.J.S. Colyn, Editor: Professor M.B.E. Sweet. Correspondence should be addressed to SAOA, Box 47363, Parklands, Johannesburg, 2121, South Africa.
