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Posterior Interbody Fusion Cages Get a Second Look

You can't always believe what you hear, see, or read. We've all said those words at some point in time. Doctors are especially on guard about test results for new drugs or implants. For example, in 1999 the Food and Drug Administration (FDA) gave its approval for a new interbody fusion cage called the Brantigan carbon fiber cage. These cages are used in posterior spinal fusion.

The original study reported good fusion rates. Complications were also low. A second study looked at the amount of blood loss and how long the operation took. Doctors at the South Texas Orthopaedics and Spinal Surgery clinic thought the values seemed out of line with what they were seeing. So they conducted their own study.

They reviewed the charts of 60 patients who had spinal fusion with the Brantigan carbon fiber cages. The operation is done from the back of the spine. The cages are placed in the back half of the disc space between two vertebral bones.

Cages can also be placed in the front half of the disc space (anterior). Cages placed in from the front tend to help keep the disc space open. They also show improved fusion rates. Cages put in from the back of the spine do the same thing, but there's a greater risk of nerve damage while putting them in. The spinal nerve roots and protective covering (dura) have to be moved out of the way to insert the cages from behind. Pulling on these tissues can cause neurological injury.

In this study, there was a 100 percent fusion rate using the Brantigan cages. Overall results were similar to the original Brantigan study. There were six cases of dural tears, but the authors don't think these were caused by cage placement. Three patients had some signs of nerve damage that went away in time.

The length of time in surgery and amount of blood loss was equal to, if not better, than the previous studies. The authors conclude that these special types of fusion cages put in from the back of the spine can be used safely with good results. They advise having an experienced spinal surgeon perform the operation.

References: Lynn Stromberg, MD, et al. Complications and Surgical Considerations in Posterior Lumbar Interbody Fusion with Carbon Fiber Interbody Cages and Steffee Pedicle Screws and Plates. In Orthopedics. October 2003. Vol. 26. No. 10. Pp. 1039-1043.

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