Posterior lumbar interbody fusion

Posterior lumbar interbody fusion has been practiced for more than 50 years. There is little question that interbody techniques offer a significantly higher fusion rate than traditional posterolateral techniques, but the morbidity associated with autograft harvest, the risks of root injury or dural tear during graft placement, and the high pseudarthrosis rate noted when allograft is substituted for autograft have conspired to minimize the widespread use of the procedure. Recently, various types of interbody cages have been developed in an effort to minimize autograft harvest requirements, reestablish disc and foraminal height, and decrease the risks of graft extrusion or collapse. Instrumentation developed for the placement of such cages has improved the surgeon's ability to perform complete discectomy, to properly prepare endplates, to reestablish lordosis, and to minimize the risk to the exiting nerve roots and dural canal. An experienced surgeon may expect fusion rates of 80% to 90% in one or two level lumbar fusions performed for degenerative disease using current techniques. Future improvements using more biocompatible or bioresorbable devices and various bone morphogenetic proteins will extend the life of these techniques well into the next century.