Excerpt from “www.surgeryencyclopedia.com”
Bone grafting is a surgical procedure that places new bone or a replacement material into spaces between or around broken bone (fractures) or in holes in bone (defects) to aid in healing.
- Osteoblasts, which produce the bone matrix.
- Osteocytes, mature osteoblasts that maintain the bone.
- Osteoclasts, which break down and remove bone tissue.
- Bone lining cells, which cover bone surfaces.
There are three ways that a bone graft can help repair a defect.
- Osteogenesis, the formation of new bone by the cells contained within the graft.
- Osteoinduction, a chemical process in which molecules contained within the graft (bone morphogenetic proteins, abbreviated as BMP) convert the patient’s cells into cells capable of forming bone.
- Osteoconduction, a physical effect whereby the graft matrix configures a scaffold on which cells in the recipient form new bone.
The term “graft” commonly refers to an autograft or allograft. A graft made of bone from the patient’s own body (e.g., hip bones or ribs) is an autograft. To obtain a piece of bone for an autograft, the patient undergoes surgery under general anesthesia. An incision is made over the crest of the hip bone, a piece of bone is removed, and the incision is stitched closed.
An allograft uses bone from a cadaver, which has been frozen and stored in a tissue bank. Allografts are used because of the inadequate amount of available autograft material, and the limited size and shape of a person’s own bone. Bones for allografts are usually available from organ and tissues donated by healthy people who die unexpectedly. Occasionally, allograft bone may be provided by a living donor. Allograft bone is commonly used in reconstructive surgery of the hip, knee, and long bones, as well as cases of bone loss due to trauma or tumors. Using allograft tissue from another person eliminates the need for a second operation to remove autograft bone or tendon. It also reduces the risk of infection, and safeguards against temporary pain and loss of function at or near the secondary site.