All spinal fusions use some type of bone material, called a bone graft, to help promote the fusion. Generally, small pieces of bone are placed into the space between the vertebrae to be fused.
A bone graft is primarily used to stimulate bone healing. It increases bone production and helps the vertebrae heal together into a solid bone. Sometimes larger, solid pieces are used to provide immediate structural support to the vertebrae.
In the past, a bone graft harvested from the patient’s hip was the only option for fusing the vertebrae. This type of graft is called an autograft. Harvesting a bone graft requires an additional incision during the operation. It lengthens surgery and can cause increased pain after the operation.
Most autografts are harvested from the iliac crest of the hip.
One alternative to harvesting a bone graft is an allograft, which is cadaver bone. An allograft is typically acquired through a bone bank.
Today, several artificial bone graft materials have also been developed.
Demineralized bone matrices (DBMs). Calcium is removed from cadaver bone to create DBMs. Without the mineral, the bone can be changed into a putty or gel-like consistency. DBMs are usually combined with other grafts, and may contain proteins that help in bone healing.
Bone morphogenetic proteins (BMPs). These very powerful synthetic bone-forming proteins promote a solid fusion. They are approved by the U.S. Food and Drug Administration for use in the spine in certain situations. Autografts may not be needed when BMPs are used.
Ceramics. Synthetic calcium/phosphate materials are similar in shape and consistency to autograft bone.
Your surgeon will discuss with you the type of bone graft material that will work best for your condition and procedure.
Immobilization
After bone grafting, the vertebrae need to be held together to help the fusion progress. Your surgeon may suggest that you wear a brace.
In many cases, surgeons will use plates, screws, and rods to help hold the spine still. This is called internal fixation, and may increase the rate of successful healing. With the added stability from internal fixation, most patients are able to move earlier after surgery.