What are the different types of bone grafts or bone graft substitutes?
Autograft
Autograft bone is the patient’s own bone and is most commonly taken from the top of the pelvis during an operation. The principal disadvantage of using autograft bone is that often another incision needs to be made to take the bone for grafting. This requires additional surgery time and can result in the following complications:
- Chronic pain at graft autograft site (10% to 25% of the time)
- Infection
- Bleeding
- Nerve damage
- Bone fracture
Allograft bone
Allograft bone (i.e., bone donated from a dead person or another patient during an operation e.g., primary hip replacement) eliminates the need to harvest the patient’s own bone.
The donor cancellous bone graft acts as a bone scaffold onto which the patient’s own bone grows and is eventually replaced over years.
There are believed to be no living cells in the bone graft (if there are, the graft is not sterile), so there is little chance of a graft ‘rejection’ as with an organ transplant.
With allograft, the speed of healing may be slower than with autograft.
There is a risk of transmission of an infection from a donor. The risk of contracting a disease such as human immunodeficiency virus (HIV) or hepatitis from an allograft has been estimated to be between 1 in 200,000 to 1 million. Case reports document that bacterial, viral and prion (e.g., Creutzfeldt-Jakob disease [CJD]) diseases have been transmitted through implantation of contaminated allografts.
Modern procurement and sterilization methods for bone tissue have lessened the risk of this occurring.
DBMs
Demineralized Bone Matrix (DBM) is a type of allograft. One of the main issues with DBMs is that the quality of the material can be highly variable dependent on the quality of the donor bone. In addition, consistent consenting of the patient receiving the donor bone, donated from a dead person, should be undertaken by the surgeon.
Synthetic Bone Graft Substitutes
Scientists have developed several alternatives, many of which are available for clinical use. These alternatives use a variety of materials, including natural and synthetic polymers, ceramics, and composites, whereas others have incorporated growth factor and cell-based strategies that are used either alone or in combination with other materials.
Key types of Synthetic Bone Graft Substitute
- Ceramic-based – calcium phosphates, calcium sulphates and calcium carbonates
- Growth factor-based – bone morphogenetic proteins or BMPs
- Collagens and Cell based grafts
