In this procedure, the surgeon fills the space left after the disc is removed with a block of bone called a bone graft. This graft may be taken from your pelvis, or it may be obtained from a bone bank. Bone graft from a bone bank is given by organ donors and stored under sterile conditions until it is needed for operations such as spinal fusion. The bone goes through a rigorous testing procedure, similar to a blood transfusion. This is in order to reduce the risk of passing on diseases, such as AIDS or hepatitis, to the recipient.
Placing a bone graft between two or more vertebrae causes the vertebrae to grow together, or fuse. If your back or neck pain is caused by segmental instability, a spinal fusion may also be recommended even if you do not have radiculopathy.
When doing a spinal fusion, the bone graft may simply be wedged in tight between the vertebrae, which holds the graft in place. In recent years, there has been an increase in the use of metal plates, pedicle (ped-i-cul) screws, and rods to try to improve the success of the fusion. Many different types of metal implants are used, and all of them try to hold the vertebrae in position while the fusion heals. Bone heals best when it is held still, without motion between the pieces trying to heal together. The healing of a fusion is no different than healing a fractured bone, such as a broken arm. In particular, the cervical spine is a difficult part of the body to hold still.