Internal Fixative Device for Anterior Fusion of Lumbar Spine
ALFRED W. HUMPHRIES, M.D.
Department of Vascular Surgery
WILLIAM A. HAWK, M.D.
Department of Pathology
ALBERT L. BERNDT, M.D.
Department of Orthopedic Surgery
SINGE Hibbs first proposed spinal fusion in 1911, the problems inherent in the operation have heretofore remained essentially unsolved. With the posterior approach, interlaminar or interspinous fusions with or without joint-facet fixation generally require a prolonged period of postoperative immobilization and an even longer period of convalescence. All of the various technics of fusion occasionally or frequently cause pseudarthrosis. Posterior fusion has an inherent mechanical disadvantage in that the support to the involved vertebrae is developed posterior to the axis of spinal flexion and extension; therefore, the everyday motion of flexion of the lumbosacral spine may cause distraction at the site of fusion. Since distraction predisposes to slow union or nonunion of bone, flexion of the spine following posterior spinal fusion must be prevented until the healing is complete.
To circumvent these problems and to permit early postoperative mobilization, anterior fusion of the spine, using a transperitoneal approach, has been proposed.1 This procedure frequently has failed, presumably because motion has occurred at the site of intended fusion. There are conceptual advantages to the interbody site for spinal fusion. It offers a large surface area for fusion, and a sufficient amount of bone to permit intervertebral metallic fixation if this seems desirable. In patients of all ages, the blood supply in the cancellous bone of the vertebral bodies is excellent. Since the vertebral bodies are anterior to the axis of spinal flexion and extension, the normal motion of vertebral flexion is not only permissible in the early postoperative period but even . . .