Posterior lumbar interbody fusion with the keystone graft: technique and results.

The technique of posterior lumbar interbody fusion reported here consists of the following steps: The confluence of the spinous process and lamina removed en bloc during the exposure is contoured into three keystone plugs; the anterior third of the disc space is packed with bone fragments; the keystone plugs are tapped in posterior to the bone fragments and locked into place; and excess bone fragments are laid over the facets bilaterally and over the transverse processes if necessary to fuse the facet joints and create a posterior fusion. This fusion technique precludes the need for banked bone or for the harvest of autogenous iliac bone, and provides posterior stability with the facet fusion despite the removal of the posterior elements. This technique has been used in 172 patients, with excellent or good results in 129 patients (75%); included in that number were 82 patients expecting compensation and 25 patients with failed-back syndrome.