Diabetes can make lumbar spinal fusion surgery much more likely to fail, a new study says.

People with diabetes are nearly three times more likely to have their vertebrae fail to properly heal and fuse together, what surgeons call a non-union complication, according to results recently published in the journal JBMR Plus.

“A lot of times the bones simply aren’t fusing,” researcher Dr. Hossein Elgafy, chief of spine surgery at the University of Toledo Medical Center, said in a news release.

Diabetics are also more than twice as likely to experience additional degeneration in places along the spine next to the spinal fusion site, a complication that usually requires extensive additional surgery, researchers said.

Diabetes appears to affect bone growth and healing following a spinal fusion, researchers said.

In the procedure, surgeons use screws, rods and bone grafts to join two or more vertebrae together.

As the area heals, the bones should fuse solidly together, restricting motion and relieving back pain. Unfortunately, diabetes appears to hamper that healing process.

“Diabetes is a metabolic disease, but it’s also a bone disease,” researcher Beata Lecka-Czernik, a professor of orthopedics at the University of Toledo, said in a news release. “It has a very significant role in bone health, and that’s what we’re seeing here.”

For the study, researchers tracked more than 500 patients who received spinal fusion surgery at the University of Toledo Medical Center between 2009 and 2017.

The team also analyzed tissue samples from patients which showed how the healing process differs between diabetics and healthy people.

“The bony samples from diabetic patients had much less developed structure, which means that even if the new bone formation happens, the quality of this new bone will be much worse,” Lecka-Czernik said.

“This is showing there is also an additional risk factor for spinal fusion complications, which is valuable for orthopedic surgeons to know when treating patients with diabetes,” she added.

Spinal fusion is generally a last resort after physical therapy and pain management have failed to help patients. Despite that, it’s common in the United States, with hundreds of thousands of spinal fusions performed every year, researchers said.

These results could help surgeons adjust their techniques to improve results in people with diabetes, researchers said.

For example, doctors can insist that diabetics get their blood sugar levels well-controlled in advance of spinal fusion surgery, Elgafy said. Meanwhile, researchers can investigate new therapies and techniques to improve new bone formation at the fusion site.

“We’ve spent 20 years improving our techniques, our hardware and our technology,” Elgafy said. “Now the new wave in spine surgery is bone health. How do we improve bone health before we take people into surgery? It’s an important question as we look to improve surgical outcomes and avoid patients having a second or third surgery. This study is an important first step.”