Bone Grafts in Spinal Fusions: What Really Matters

The search for the perfect spinal fusion bone graft material goes on, but the good news is you can achieve positive patient outcomes with any of the common choices. Hear what experts at NASS 2020 had to say.

Spine surgeons have several choices for osteobiologics, but no clear and consistent guidance on which may be best for a given procedure. The result has been wide variation in graft materials and techniques for spinal fusion surgeries. 

Best bone graft materialWhat is the best bone graft material? But choosing the perfect bone graft material, it turns out, may not be as pressing a matter at first blush when it comes to spinal fusion. Here’s what some of the presenters at the 2020 conference of the North American Spine Society (NASS) had to say.

Cervical Fusion: (Almost) Anything Goes

Should you be intent on choosing an optimal biologic to promote osseous union in cervical fusion? Bone union is the point, after all. You want the best material to help bone heal so your patient has better outcomes and faster recovery. You know that nonunion can lead to ongoing symptoms and revision surgery down the line.

But cervical fusions have the potential to heal well regardless of the graft material used, according to some research—and according to a NASS 2020 presentation.

As Jeffrey C. Wang, MD, chief of the orthopaedic spine service at USC’s Keck School of Medicine and and co-director of USC Spine Center, explained at NASS: “People tend to do well with these fusions, regardless of fusion material, even regardless of pseudoarthrosis. For whatever reason, the cervical spine tends to have higher fusion rates than lower parts of the spine.”

Of course, sometimes bones don’t heal as we’d like them to. But even then, Dr. Wang says, “an abundance of research still points to good outcomes for a lot of people.”

As for graft material, that also doesn’t seem to make a difference in cervical fusions. In terms of approach, autograft has long been considered the gold standard. Dr. Wang says other materials and approaches—especially allograft with a plate—are also proving highly successful.

“You can pretty much use whatever you want [and get a] pretty high healing rate,” Dr. Wang says. “If there are differences, all the studies that look at them have small numbers of patients, so it’s hard to make meaningful comparisons with this consistently high healing rate.”

Lumbar Interbody Fusions: Self-Care First, Then Surgery

Lumbar interbody fusions typically have high healing rates with good outcomes. But unlike cervical fusions, some features are clearly more beneficial than others from the strict measure of osseous fusion.

R. Todd Allen, MD, PhD, associate professor of orthopaedic surgery at UC San Diego Health, presented at NASS his take on the available graft research for lumbar spine interbody fusions (anterior, lateral, or oblique). One important takeaway: Graft materials may not be as important as surface structure. “Porous, rough surfaces increase implant fixation by mechanically interlocking with bone,” Dr. Allen said.

A (older but detailed) 2010 review in the International Journal of Spine Surgery compared advantages and disadvantages of bone grafting options for lumbar fusions:

  • Iliac crest harvest
  • Autologous bone from other donor sites
  • Allogenic bone
  • Ceramics
  • Recombinant human bone morphogenetic proteins

“Although iliac crest remains the gold standard,” concluded the authors, “reported success with alternative approaches, especially in combination, has shown promise.” Considering the high rate of success with ALIF and related procedures, you may want to focus less on graft selection and more on holistic patient care.

For example, Dr. Allen emphasizes a focus on any patient factors that could require preoperative correction and optimization. He suggests focusing and educating patients on:

  • Vitamin D levels. Vitamin D deficiency is an independent risk factor for nonunion – in addition to being associated with poor health-related quality of life, worse pain and disability scores, and increased infection rates. It’s also highly modifiable.
  • Bone mineral density. In spine surgery patients over 50, osteoporosis is associated with several worse pain, higher complication rates, and poorer fusion rates, to name a few challenges. It’s possible that bone-building treatments may improve these outcomes, though results are mixed. Some research does suggest that bisphosphonates may reduce the risk of subsequent spinal fractures, time to fusion, and pedicle screw loosening.  
  • Other modifiable risk factors. Potential targets for intervention to improve bone quality – ideally to improve fusion rates and postsurgery outcomes, include metabolic syndrome, adequate nutrition, and alcohol and/or tobacco use, among others.

Not only would improving these modifiable risk factors increase the likelihood of a successful surgery, it would promote the overall health of the patient and thus reduce the risk of future health care needs and expenditures.

Updated on: 12/15/20
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