Bone graft harvesting is done to increase the chance of a successful joint fusion (ex. ankle fusion, subtalar fusion, talonavicular fusion) or to help a non-union heal. The soft (cancellous) bone is scooped out and packed into the area where the bone healing is required. The bone graft helps healing in three ways:
- It provides a scaffold for new bone to form on;
- The bone graft provides a stimulus for healing elements (growth factors, etc) to migrate to the healing area; and
- Bone cells (osteocytes) found in the bone graft may produce new bone directly
Common sites for harvesting bone graft in foot and ankle surgery include: the proximal tibial, the iliac crest, and the calcaneus. There is some suggestion that the closer to the center of the body the better quality the bone graft (i.e. iliac crest may be better than proximal tibial bone graft which may be better than a calcaneal bone graft).
When bone graft is taken from the patient and transferred to another area of the body it is called an autograft as opposed to bone that is taken from a cadaver which is called an allograft. Allograft lacks the bone stimulating properties of autograft bone. There are now also a number of “bone graft substitutes” that attempt to stimulate bone formation by including bone stimulating elements (ex. platelet dervived growth factors, bone morphogenic proteins, etc.) within the substance.
