The Screwy Results of Spinal Fusion Surgery: “External Fixation” Doesn’t Predict Whether Surgery Spells Relief

Spinal fusion surgery is often used to treat back pain. But even when the vertebra are successfully joined together, this surgery only relieves pain about 70 percent of the time. Doctors would like to be able to predict who benefits from this type of surgery (called “arthrodesis”). That way, they can avoid doing surgery on patients who will get little or no benefit.

Past research suggests that external fixation may predict whether patients feel better after surgery. With external fixation, a metal device is placed over the outside of the patient’s back. Screws are inserted into the back of the spinal column above and below the sections that are to be fused together. This is done while the patient is asleep from anesthesia. External fixation was first used to heal breaks in the spine. It has since been found to reduce back pain by holding the spine in place. This author wanted to see whether patients who got relief from this procedure before spinal fusion surgery would go on to have good results after surgery. 

External fixations were tried on 103 patients. Patients averaged 45 years old. One hundred procedures were completed. Nerve complications occurred in two procedures; one of these led to permanent problems. Five patients had infections. Infections were rare when patients had antibiotic treatment while wearing the fixation device. Devices were removed after two weeks.

Sixty patients had pain relief with external fixation. These patients were thought to be good candidates for spinal fusion surgery. Forty-nine patients went on to have the surgery. They were then observed for at least one year.

Did patients who felt better from external fixation have good results from surgery? Though the fusions were successful, only about half of the patients had enough pain relief to show better function at follow-up. About a third of the patients felt the same after surgery. And eight percent were actually doing worse.

From these results, the author concludes that external fixation should not be used to decide which patients will benefit from surgery to fuse the spine. External fixation can have complications. Other procedures may be more successful in deciding who gets good results from spine surgery.