Study finds anterior and posterior spine fusion equally successful

More blood loss and OR time found with posterior iliac crest.

WASHINGTON - The long-standing debate over the best procedure for degenerative spinal diseases may prove moot as a new study shows similar outcomes for posterior and anterior treatments.

Researchers examining patients with single level disc disease discovered that both methods improved discomfort and found no statistically significant differences in Oswestry, SF-36, back and leg pain scores between the procedures.

"So what we're saying essentially is that all these patients improved equally whether they had anterior or posterior procedures as far as all the clinical outcome measures," said John R. Dimar II, MD, associate professor at the University of Louisville department of orthopaedic surgery, during his recent presentation at the American Academy of Orthopaedic Surgeons 72nd Annual Meeting.

The Medtronic Sofamor Danek-supported study finally provides surgeons with the comparative data they have been looking for. "… this is the first study to really compare the clinical outcomes selected in a prospective manner of two different surgical techniques for a similar indication using the same study outcome protocols at six weeks, three, six, and 12 months," said Dimar, who also is a consultant for the company.

Slight differences, similar outcomes

The research compares two studies examining the efficiency of posterior and anterior spinal fusion. The first study consisted of patients receiving anterior fusion with LT-Cages. Patients were randomized to receive iliac crest bone or rhBMP-2 collagen sponges, Dimar said. Similarly, a second study included patients with posterior fusion performed with iliac crest or rhBMP-2 applied to a tri-calcium phosphate, hydroxyapatite and collagen sponge. According to the abstract, 150 patients participated in the study.

Dimar said that the patients showed comparable characteristics, but the anterior group reported greater numbers of prior surgery and three times more workman's compensation. Further research matching patient diagnosis proved difficult due to insufficient records. "Believe it or not, the FDA did not require a specific diagnosis to be enrolled in the study, just a surgical indication," Dimar said. "So, we weren't able to look and compare exactly apples for apples or oranges for oranges to everyone that's there…"

Study outcomes mirrored each other between groups at all follow-ups, except SF-36 scores, but after 12 months even "the SF-36 also showed no statistical difference," Dimar said. "Although there was a slight bias toward the anterior procedure at one year."

Despite parallel improvements in pain, anterior treatments did show some additional benefits, Dimar said. "The surgical data shows a very nice stratification that, basically, the anterior procedure using the cage with a BMP sponge was much better as far as overall time, blood loss and hospital stay," Dimar said. Iliac crest patients receiving posterior treatment stayed in the operating room longer and lost 300 ccs more blood. The group often required nerve decompression, which Dimar said could have caused the increased blood loss.

Complications

The researchers continue to study the groups and have collected two-year follow-up information. A future study will report the groups' complication rates. "And [in] my initial look at that data, a couple of months ago, there wasn't any real difference between doing [operations] anteriorally [or] posteriorally in experienced hands," Dimar said.

For more information:
Dimar JR, Glassman SD. Burkus, JK, et al. Comparison of prospective clinical outcomes for anterior versus posterior single-level spine fusion. #183. Presented at the American Academy of Orthopaedic Surgeons 72nd Annual Meeting. Feb. 23-27, 2005. Washington.