All Spinal Fusions Are Not Alike
The best treatment for chronic or long-term back pain is still a mystery. When pain doesn't respond to drugs, exercise, or rest, doctors may consider fusion as a possible option. Fusing the problem part of the spine together doesn't always relieve pain either. Generally, only half the patients get better with spinal fusion.

The authors of this study compared two methods for fusing the vertebrae of the low back area. Posterolateral and circumferential are the two types of fusion reviewed. The doctor uses tools to enter the spine from the back of the body in both these methods.

With posterolateral fusion, pieces of bone, called bone graft, are placed alongside the back surfaces of the spine. The disc remains in place. In the circumferential approach, the disc is removed from between the vertebrae. Then a cage filled with bone chips is placed inside the disc space. The cage lifts and holds the vertebrae apart, regaining the disc height. In both types of fusion, screws and rods are usually applied to hold the spine in place.

Patients in both groups had less pain and numbness and could walk further. Patients also reported psychological improvement. Some tests showed no difference in the results between the two groups.

More patients with the circumferential fusion returned to work. The authors think this is because the disc height was kept the same with a more even load distributed through the spine. Fusion rates were slightly higher in this group.

Even with a good fusion, patients don't always get better. The authors report that lower results sometimes occur because of psychological, social, or economic reasons. They advise careful selection of patients before doing spinal fusions, regardless of which type of fusion is to be used.
References
S. S. Madan, MCh, MSc, MBA, et al. Circumferential and Posterolateral Fusion for Lumbar Disc Disease. In Clinical Orthopaedics and Related Research. April 2003. Vol. 409. Pp. 114-123.