Bone graft for spinal fusion comes from one of four main sources: your own body, a donor, a synthetic material, or a biologic product that stimulates bone growth. The most common source is still your own bone, typically harvested from the hip, though surgeons increasingly use alternatives depending on the type of fusion and the amount of bone needed.
Your Own Bone (Autograft)
Autograft remains the gold standard for spinal fusion because it’s the only graft material that does all three things needed for successful fusion: it provides a scaffold for new bone to grow on, it contains growth factors that actively recruit bone-forming cells, and it brings living bone cells that can immediately start building new tissue. No other graft source combines all three properties.
The most common harvest site is the iliac crest, the curved ridge of your hip bone. Surgeons can take bone from the front or back of the iliac crest depending on the type of spinal surgery. Front-of-hip harvests are typical for cervical (neck) fusions, while back-of-hip harvests pair with posterior spinal fusions since the surgeon is already working in that area. The iliac crest provides both solid structural pieces and softer, spongy bone chips, making it versatile for different fusion needs.
The tradeoff is donor site pain. Studies show that roughly 73 to 91 percent of patients experience short-term pain at the hip harvest site, depending on the surgical technique used. Minimally invasive harvesting with a tube-shaped cutting tool produces less acute pain than traditional open harvesting. Chronic pain lasting beyond a year is uncommon, affecting about 2 to 4 percent of patients. Minor complications like superficial wound issues occur in roughly 8 to 12 percent of cases. These downsides have driven the search for alternatives, and some surgeons have explored less common autograft sites like the breastbone or upper shinbone.
Local Autograft
When your surgery includes a decompression procedure, where the surgeon removes bone that’s pressing on your nerves, that removed bone can be recycled as graft material. This is called local autograft, and it’s essentially free material that requires no second surgical site. The bone is simply moved from where it was causing problems to where the surgeon wants fusion to occur. Local autograft is often the first choice when enough bone can be collected during the decompression, but larger fusions may need more material than decompression alone provides.
Donor Bone (Allograft)
Allograft is bone harvested from deceased human donors and processed through tissue banks. It provides a scaffold that your body can gradually replace with new bone, but it lacks living cells. This makes it a good option for filling space and adding bulk, particularly when used alongside local autograft to extend the total volume of graft material available.
Safety is the natural concern with donor tissue. Modern tissue banking involves a rigorous screening process that includes reviewing the donor’s medical records, social history, and physical examination, followed by required testing for HIV, hepatitis C, and other infectious diseases. The FDA has mandated specific screening and testing protocols since 1993, and nucleic acid testing for HIV and hepatitis C has been required since 2005. After recovery, the bone goes through multiple cleaning and disinfection steps that can include antibiotic soaks, chemical washes, and mechanical cleaning. Most allograft receives a final sterilization step, most commonly gamma irradiation, in its sealed packaging. Disease transmission, while theoretically possible, has become extremely rare with these modern processing methods.
Demineralized Bone Matrix (DBM)
DBM is a processed form of donor bone that sits between standard allograft and biologic products. Donor bone is ground into particles, then soaked in acid to strip away the hard mineral content. What remains is the protein-rich organic framework of bone, which still contains natural growth factors, including bone morphogenetic proteins. These growth factors can recruit your body’s stem cells and coax them into becoming bone-forming cells.
After processing and freeze-drying, DBM is formulated into putties, pastes, or flexible strips that surgeons can mold into the fusion site. Clinical studies comparing DBM mixed with autograft against autograft alone in posterior lumbar fusions have shown similar fusion rates between the two approaches. DBM is commonly used as a graft extender, meaning it’s mixed with a smaller amount of your own bone to stretch the available material across a larger fusion area.
Synthetic Bone Grafts
Synthetic grafts are lab-manufactured materials designed to mimic the mineral structure of natural bone. The two most common types are hydroxyapatite and beta-tricalcium phosphate, both made from calcium and phosphate, the same minerals that make up about 70 percent of your natural bone.
Hydroxyapatite closely matches the mineral composition of real bone and provides a long-lasting scaffold. Beta-tricalcium phosphate dissolves faster in the body, which can be an advantage because it’s gradually replaced by your own bone, but the downside is that it may lose structural volume before new bone fully fills in. Both materials support bone cells attaching, multiplying, and forming new bone on their surfaces. Synthetic grafts are cleared for use as autograft extenders in posterolateral spinal fusion, meaning they supplement your own bone rather than replace it entirely.
Bone Morphogenetic Protein (BMP)
BMP-2 is a lab-made version of a protein your body naturally produces during bone healing. Rather than providing a physical scaffold, it works as a chemical signal. When placed at the fusion site on a collagen sponge carrier, it binds to stem cells and triggers a chain of events that converts those cells into osteoblasts, the cells responsible for building new bone. The protein essentially tells your body to grow bone in a specific location.
BMP-2 received FDA approval in 2002 for use in anterior lumbar interbody fusion inside a specific type of cage device. In the clinical trial that led to approval, fusion rates exceeded 90 percent at two years, matching the results of traditional hip bone autograft. It has also been studied for posterolateral fusion using a ceramic carrier made of hydroxyapatite and tricalcium phosphate. BMP-2 eliminates the need for a hip harvest site entirely, but it’s approved for limited indications and carries its own risk profile, particularly swelling, which can be significant in cervical spine procedures.
How Surgeons Choose the Right Graft
The choice of graft material depends on several intersecting factors: the location of the fusion (cervical, thoracic, or lumbar), the surgical approach (front or back of the spine), the number of levels being fused, and whether a decompression is being performed at the same time.
Single-level fusions with decompression often generate enough local autograft to complete the job without harvesting from the hip. Multi-level fusions typically require more material, which is where allografts, DBM, or synthetics come in as extenders. Anterior cervical fusions frequently use structural allograft or cages filled with graft material. When hardware like pedicle screws and rods are used alongside the graft, fusion rates improve regardless of the graft source. One large meta-analysis found that iliac crest autograft alone achieved fusion rates around 86 percent, but adding metallic implants pushed that to about 92 percent. Local bone autograft with hardware achieved the highest pooled fusion rate at roughly 95 percent.
In practice, many surgeons use a combination: local autograft from the decompression mixed with DBM or allograft chips to fill the fusion bed, supported by metal instrumentation. This approach avoids a separate harvest site while still providing living bone cells, growth factors, and structural scaffolding where it’s needed most.