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Lower Spine News

One Cage or Two for Spine Fusion?

Spinal fusion is an important treatment for low back pain. Many studies have been done since the 1950s on how to do this operation. Today there are many different ways to fuse the spine -- and many opinions about the results. Doctors don't always agree on the best way to fuse the lumbar spine.

Researchers haven't given up on studying spinal fusions. This study was done in the military. Thirty-five men with disc disease at one level in their low back were chosen. The problem disc was removed, and bone graft was placed in all patients. The bone graft was first put inside a fusion cage. Surgeons implant the cage into the disc space between the two vertebrae where the disc is removed. This makes it an interbody fusion (one that occurs "between two vertebral bodies"). When the surgeon does this surgery from the back of the spine, the operation is called posterior lumbar interbody fusion (PLIF).

One group received a single fusion cage; the other group got two cages. Fusion cages are usually made of bone, titanium, or graphite. They help hold the two spine bones apart while the bone graft fuses. The cage also helps distribute the load on the spine.

The authors wanted to know whether one or two cages work best for PLIF operations. Results of this study were based on patient satisfaction, pain levels, and function. X-rays were also used to measure the fusion. There were no differences in length of hospital stay between the two groups. Complications were about the same, and no one had a deep infection after the operation. Four of the 35 patients had a tear of the lining around the spinal cord. Three of these four were in the two-cage group. Both groups had increased function after the fusion. Pain was decreased the same in both groups. Patients were equally satisfied whether one or two cages were implanted.

The authors conclude that there is no difference in results with PLIF using one or two fusion cages. Using only one cage is less expensive and involves fewer dural tears. The authors say to keep in mind, that this is a small study. The results are only a beginning in the quest to know which choice is best -- one cage or two.

MAJ Robert W. Molinari, MD, et al. Are Two Cages Needed with Instrumented PLIF? A Comparison of One Versus Two Interbody Cages in a Military Population. In The American Journal of Orthopedics. July 2003. Vol. 32. No. 7. Pp. 337-343.


*Disclaimer:* The information contained herein is compiled from a variety of sources. It may not be complete or timely. It does not cover all diseases, physical conditions, ailments or treatments. The information should NOT be used in place of visit with your healthcare provider, nor should you disregard the advice of your health care provider because of any information you read in this topic.
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