Bone Graft Types
A basic part of any spinal fusion involves a bone graft. Doctors use bone grafting for many types of orthopedic procedures that require bones to heal. Bone grafting provides two solutions during orthopedic procedures:
- to stimulate the bone to heal
- to provide support to the skeleton by filling gaps between two bones
Doctors use bone grafts to stimulate the healing process of bones. Additionally, crushed bone tissue placed around a fracture or a fusion site has chemicals in it that stimulate the nearby bones to heal. If the bone is from the patient’s own body, osteocytes (living bone cells) may survive the transfer to the new location and continue to do their work of making new bone. Even bone taken from someone else will stimulate the bone to heal. But bone taken from the same person may be better because the chances are higher that it will have remaining live bone cells after the transfer.
A bone graft refers to a supporting structure. Rather than crush the bone into fine pieces, larger pieces of bone fill gaps or voids between two bones. For example, if the surgeon removes a vertebra or disc, he or she may place a chunk of bone graft into the empty space. To clarify, the hard or rigid bone will hold the bones apart while the body grows to the ends of the graft. Over time, the entire piece of bone that was grafted will be “remodeled” and replaced by the body with new bone. Also, the time it takes to fuse depends on the size of the piece of bone that was used. It sometimes takes a long time to completely heal — a slow process that may take several years.
Autograft vs. Allograft
Your surgeon will try to promote and speed the healing of your spinal fusion in a number of ways. The most common approach uses your own bone whenever possible. The term autograft refers to bone taken from your own body. The term allograft refers to a bone graft taken from someone else’s body. The surgeon may mix allograft with autograft.
Allograft can come from many types of bones in many different forms. Allograft usually comes from organ donors and are placed in bone banks. Bone banks test the bone to ensure diseases such as hepatitis and AIDS do not exist — just like testing done in a blood bank. When the bone graft does not come from the patient, it does not contain any living cells, and therefore, has fewer chemicals to stimulate the growth of new bone.
The disadvantage of an allograft reveals that it may not always grow as well or as quickly as an autograft, but a bone-growing protein can be added to the area to make up for what the bone graft lacks. The advantage of using an allograft occurs when the patient does not have to donate the bone graft. This makes the surgery shorter, and there may be less pain afterward. The allograft carries a very small risk of transferring infectious diseases even though rigidly tested.
An allograft provides an advantage if the operation requires more bone graft than your own body can supply. Some major spine fusions need a lot of bone graft. Some surgeries need large pieces of structural bone graft, which may cause problems in the area of the body where the bone was removed.
New Technology for a Bone Graft
Medical research continues to design bone graft substitutes, chemicals, and devices that stimulate the bones to fuse. Furthermore, Electrical current stimulates bone to grow and so surgeons use electrical stimulation devices to speed up a fusion. In Addition, some artificial bone graft materials have been developed. For instance, sea coral, harvested from the oceans, sometimes provides a successful structural bone replacement. Other developments include
- Demineralized bone matrix (DBM): Developed from cadaver bones in a bone bank. The bone has the calcium removed and can be turned into a putty, sheet, or gel. The material can then be added to a graft site to improve the fusion.
- Autologous growth factor (AGF): A solution used to stimulate bone growth. Developed in a laboratory from blood platelets (the clotting part of the blood). The mixture is usually used in combination with some form of structural support, such as autograft or fusion cages.
- Bone morphogenic protein (BMP): A chemical added to bone graft to enhance bone growth when added to a fusion site.
If you or a loved one suffers from spinal pain, you owe it to yourself to call Southwest Scoliosis and Spine Institute at 214-556-0555 to make an appointment.