Spinal reconstruction: quo vadis?

Spinal surgery has evolved from early Egyptian times to the present through generations of new concepts, designs, procedures, and technology. In 1862, Edwin Smith discovered the works of Imhotep, Vizer of Djoser, who recorded his treatment of spinal cord injury, as well as spinal dislocation and subluxation, around 2000 B.C.11,20 In 1882, William F. Wilkins described and performed the first spinal stabilization procedure in a neonate with T12–L1 dislocation.38 In the years that followed, several individuals began to develop instrumentation systems to help accomplish the goal of operative spinal stabilization. Dr. Berthold Hadra first described the use of wire and the technique of securing spinous processes together in the treatment of a cervical fracture.38 In 1909, Fritz Lange described the use of steel rods or celluloid bars secured to spinous processes with either wire or silk to help stabilize the spine.6,7,53 The idea of onlay bone to accomplish fusion was introduced in 1911 by Fred Albee.1 He harvested thin strips of tibia and placed them into the base of splint spinous processes. Hibbs decorticated the lamina and placed overlapping autogenous strips over the decorticated dorsal surfaces to facilitate fusion.6,7,47 After the advent of dorsal onlay fusion, unique instrumentation concepts were advanced. In the 1940s, Don King51 reported the use of facet screws for spinal stabilization. The use of the pedicle as a fixation point was initially described by H.H. Boucher of Vancouver in 1959.10 However, it was Harrington and Tullos who simultaneously described pedicle spinal fixation using screws in conjunction with hooks linked to steel rods to achieve spinal stabilization.6,7,42,43 Harrington’s system was developed for the treatment of spinal deformities that developed as a sequela to poliomyelitis. Initially, Harrington used facet screws to achieve spinal stability. Although the immediate correction was satisfactory, his early constructs subsequently failed.41 This led to system modification, akin to present day systems, of a threaded rod and hook construct (Fig. 25.1). It became apparent over time that using Dr. Harrington’s hook-rod construct without bone grafting had its limitations. This form of non-segmental instrumentation without attempted bony fusion had a high rate of hook and rod failure with recurrence of deformity. Segmental spinal stabilization, which capitalizes on load sharing by multiple vertebral levels, thereby enhancing construct durability, was subsequently developed. The first of these systems was the Luque instrumentation system utilizing segmental sublaminar wires.6,7,20,59,60 Despite the improved success rates of hook-rod with sublaminar wire constructs, there was still sufficient hardware failure to drive the search for more appropriate and substantial spinal fixation devices and techniques. Although Harrington attempted pedicular fixation, he had difficulty with screw/rod fixation and therefore abandoned the idea.44 It is Roy-Camille who is credited with the advent of contemporary techniques to use the pedicle as a fixation point for spinal implants.77 Rigid pedicle fixation into the vertebral body affords three-column spinal fixation.23 Therefore, fewer spinal segments are required for incorporation within a spinal fusion construct to achieve stabilization. For these reasons, pedicle screw segmental fixation with a screw-rod construct affords significant advantages over much longer, non-segmental spinal stabilization techniques and instrumentation systems. Although dorsal onlay posterolateral fusion of the lumbar spine gained popularity, fusion rates were suboptimal. With realization of the biomechanical principles of the human spine, rather than just its structural features, it became understood that the use of interbody bone grafting would lead to restoration of disc height, the removal of the disc as a potential pain generator, and that vertebral replacement could be accomplished with a noncompressible structural bone graft.6,7 The first description of a posterior interbody fusion (PLIF) was published in 1953 in the Journal of Neurosurgery.18 Since that time, PLIF techniques have gained widespread acceptance, and lumbar fusion success rates have improved compared with dorsal lumbar onlay fusion procedures. Many surgeons consider PLIF to be the procedure of choice for intervertebral bony stabilization of the lumbar spine. This procedure too has limitations, including the need for thecal sac and nerve root retraction, potential cerebrospinal fluid (CSF) leak, dysesthetic nerve root pain syndromes, and epidural fibrosis.63 Copyright © 2006 by Lippincott Williams & Wilkins 0148-703/06/5301-0229