The mechanics of thoracolumbar fractures stabilized by segmental fixation

Patients with unstable thoracolumbar spine fractures greatly benefit from the rapid mobilization made possible by surgical reduction and secure internal fixation. The Harrington distraction method provides excellent hook fixation to the spine but is attached only to the proximal and distal ends of the instrumental segment and is dependent on an intact anterior longitudinal ligament. Because the spine is multisegmented and viscoelastic, a distraction method alone may not provide persistent tension on the anterior longitudinal ligament. Segmental spinal instrumentation (Luque) is less efficient in obtaining reduction because it has no built in distractive mechanism. In addition, the lack of laminar hook attachments is a significant disadvantage in maintaining a distractive force. A combined system consisting of Harrington distraction rods segmentally attached to all available motion segments improves the currently available mechanical construct for obtaining and maintaining reduction in unstable thoracolumbar fractures.