Pathogenesis and prophylaxis of postlaminectomy deformity of the spine after multiple level laminectomy: difference between children and adults.

The pathogenesis of postlaminectomy spinal deformity and instability in children was evaluated by reviewing appropriate roentgenographic findings. First, we reviewed spine roentgenograms of patients below 40 years of age who underwent spinal fusion for deformity and instability of the spine developing after a multiple level laminectomy. Two types of deformity were recognized on the roentgenograms: increased mobility between the vertebral bodies and wedging deformity of the ventral aspect of the vertebral bodies. Second, we did a follow-up study of another group of patients who had undergone laminectomy. We found the same two types of deformity in children, but not in adult patients. The incidence of deformity was higher after laminectomies of the cervical or cervicothoracic region than after lumbar laminectomies. Our data suggest that postlaminectomy spinal deformity can develop in children without irradiation or facet injury. The deformity is due to a wedging change in the cartilaginous portion of the vertebral body and to the viscoelasticity of ligaments in children. When treatment of this complication becomes necessary, anterior fusion may be effective in arresting progression. Prophylactic measures against the development of deformity are discussed. Our hypothesis concerning the mechanism of development of this complication supports the rationale of osteoplastic laminar resection and reconstruction instead of laminectomy, particularly in the management of children.