In this review article, experts in the field of orthopedic trauma report on the use of bone graft substitutes in surgery. Types of grafts, results of studies so far, and recommendations based on research evidence are presented.
Many patients who need a bone graft donate their own bone. It’s usually taken from the pelvic bone. But problems with the donor site have led scientists to look for better ways to enhance bone healing. Bone graft substitutes are being studied and developed.
In the mid-1990s, a group of 15 proteins was discovered that can help new bone form. These are called bone morphogenetic proteins or BMPs. Doctors see this as a potential treatment for fractures, especially nonunion fractures (breaks that don’t heal).
Some efforts to develop bone substitutes are still in the animal study stages. Others have been used in clinical trials for humans. For example, demineralized bone matrix (DBM) is one source of bone stimulating proteins.
When used in spinal fusions, the DBM has been mixed in a 2:1 ratio with bone graft with good results. This type of use as a bone-graft extender will need further research. Right now the FDA has plans to regulate DBM products as Class-II medical devices. Gene technology used to form the DBM has higher risks and is classified as a Class-III device.
Osteogenic protein-1 (OP-1) is a recombinant BMP available for clinical use. Recombinant means two DNA sequences have been added or combined together to form a new sequence that isn’t found naturally.
Studies with OP-1 have shown a faster healing time, improved wound-healing, and decreased rates of infection in trauma patients. Similar good results were also reported in patients who are smokers. Tobacco use is a known risk factor for poor or delayed healing.
Other studies have shown that growth factors added to DBM are needed to prevent bone graft failure. Composite grafts combining various materials together for the best effect are the subject of much study now. For example, bone marrow mixed with BMP or injected alone seems to work well in animals.
Platelets delivered in the early stages of bone repair may start the steps toward successful fracture healing. Other ways to enhance bone growth in humans will remain a research topic for years to come.