The use of bone grafts in foot and ankle surgery is a topic
of interest to the podiatric surgeon.
Bone grafting may be used in various procedures to replace a defect in
the bone, to extend or lengthen a certain bone in the foot, to aid in the
fusion of two bones, or in other instances where extra material is needed. A comprehensive understanding of the biologic
principles of bone healing and bone grafting is necessary for the use of these
materials. Some of the information
involved in bone grafting may be passed along to the patient as well.
In order for a bone graft to be useful in the body, it must
possess certain properties. These
properties are osteoconduction,
osteoinduction, and osteogenesis. Osteogenesis refers to the formation of new
bone. This can only take place in a
transplanted piece of bone that is used as a graft when the osteoblasts, or the
cells responsible for laying down new bone, are transplanted with the graft and
are kept alive. This is really only
possible in a bone graft that comes from the same person that it is being used
in, such as a bone graft harvested from the iliac crest that is transplanted
into the foot.
Osteoconduction refers to the ability of a bone graft to
allow as a matrix for new bone to grow into.
Once a bone graft is placed into the body, it must be resorbed and
incorporated into the body. A highly
osteoconductive material would allow the cells responsible for new bone
formation and vascular tissues to easily maneuver into the bone graft.
Osteoinduction refers to the process by which new bone
growth is stimulated in the host’s body. This occurs when the host’s stem cells are
activated and brought to the site of the bone graft, and differentiate into
bone cells. This process is induced by
bone morphogenic proteins (BMPs), platelet derived growth factors, and an array
of other chemicals, or cytokines, that attract cells to the area.
Depending on the type of bone graft used, there is generally
a mixture of osteoinductive and osteoconductive properties incorporated into
the material. The only materials that
will have osteogenic properties are real bone of the patient.
The use of cortical bone (the tough, highly consolidated
outside of a bone) and cancellous bone (the spongier, highly vascular inside of
a bone) is also a consideration in bone grafting. Generally speaking, cancellous bone offers a
structure that is highly osteoconductive and osteoinductive, while the cortical
bone offers strength to the bone graft.
Bone grafts are used with great success in foot and ankle
surgery, largely due to the fact that these parameters are all considered by
the operative surgeon. The popularity of
synthetic materials used as bone grafts speaks to the successful outcome of
their use.
Central Florida Foot & Ankle Center, LLC
101 6th Street N.W. Winter Haven, FL 33881
Phone: 863-299-4551
www.FLFootandAnkle.com
