(Please click on pictures for a more detailed view)

Fig. 5: X-Ray showing BK cages in place

The painful mechanical instability of the lumbar spine associated with spondylolisthesis and degenerative disk disease is difficult to manage. Patients experience symptoms associated with compression of the nerve roots and cauda equina. Back pain is usually the primary complaint making it important to differentiate the pain from that caused by musculo-ligamentous strain. It is for this reason that we stress the importance of extensive conservative therapy before considering surgical intervention. Plain x-ray flexion / extension films may demonstrate movement of one vertebral body over the other as well as reduced disk space height (figs. 1&2). A positive diskogram, where injection of radiopaque dye into the affected disk reproduces the patients pain and outlines a fissured or ruptured disk, localizes the level of involvement. While compression may be caused in part by herniation of the disk, diskectomy alone is not effective in providing relief since additional impingement is produced by the reduction in disk space height and abnormal amount of movement allowed by the joint.

In Lumbar Inter-body Fusion with cages the disk is removed and titanium cages filled with bone are inserted between the vertebral bodies in order to maintain disk space height and fuse the joint, thereby eliminating abnormal movement (figs. 3-6). This is a state-of-the-art procedure, as the cages used for this are new and revolutionary in concept. Compared to a "posterior fusion" with pedicle screws where the posterior elements and not the vertebral bodies are fused, it is felt that the interbody fusion with cages has a greater chance for a successful fusion. This is because gravity aids in immobilizing the interbody space for an interbody fusion which is not the case for posterior fusions (fig. 7). Typically, PLIF with cages is only performed on patients with 6 months of intolerable pain in whom all forms of conservative treatment have failed.

Patients are kept in the hospital for 1-2 days after the procedure, and are usually able to return to work in 6-9 months. A preliminary review of our results demonstrates a success rate of 75% in relief of pain and return to full activity, similar to other reports in the literature¹. We currently have a prospective study conducted by an independent researcher underway with a 1-2 year follow-up that will further define outcomes.

Fig. 6: Axial CT scan showing cages in place

Fig. 7: The cages are "in-line" with gravitational force allowing for more stability and a greater fusion rate than posterior fixation