Orthobiologics for the Foot and AnkleOrthobiologics -- what in the world is that? Orthobiologics refers to growth factors and proteins used to help bone and soft tissues heal. It's a fairly new area of study and development. These biologic agents are applied during surgery with the goal of boosting the body's natural healing process.
Right now, there are three major orthobiologic products available for use during surgery. These include: 1) platelet-rich plasma (PRP), 2) bone morphogenetic proteins (BMPs), and 3) platelet-derived growth factor (PDGF).
In this review article, surgeons from the Department of Orthopedics at the University of Medicine and Dentistry in New Jersey (UMDNJ) discuss each one of these growth factors. The specific focus is on the use of growth factors in foot and ankle surgery. A summary of what's been published is included for each product.
Let's take a look at the first one mentioned: platelet-rich plasma. The patient donates his or her own blood for this procedure. The blood is separated in order to collect the platelets. Platelets travel around the body in the blood at all times. They are always ready to be available. When a cut or bleeding injury occurs, the platelets act like superglue and quickly form blood clots to stop the bleeding.
Platelets are full of various growth factors. Growth factors are important in wound healing because they are like the Maitre d' (the man in charge at a restaurant). They signal to the waiters (other cells needed for inflammation, healing, and tissue recovery) when and where to go (the site in need of attention). Each stage of soft-tissue and bone healing requires different kinds of cells to complete the process.
Surgeons have found more and more uses for platelet-rich plasma. It started with mouth and jaw surgery and now extends to include bone healing in spine fusions, fracture repair, surgery to lengthen an uneven leg or arm, and tendon healing.
It makes sense that this same product could be used with ankle fusions. And especially when the patient is at high-risk for infection, delayed wound healing, or other complications after surgery. Studies show that platelet-rich plasma also works well for ankle fractures that aren't healing well, for ankle joint replacements, surgery to correct foot deformities, and repair of Achilles tendon ruptures.
The platelet product can be painted on bone, sprayed on the surface of ankle implants used in joint replacements, or injected into healing tendons. The results are all the same: faster fusion or healing time. In the case of tendon repair, joint range of motion, function, and return to full activities improve much faster as well.
The next orthobiologic product reviewed is bone morphogenetic proteins (BMPs). These proteins specifically target bone growth. Scientists have discovered more than 20 BMPs so far. They have even managed to genetically engineer two bone growth factors for use with fractures and fusions.
Each of the 20 natural BMPs seems to have a slightly different job to do when it comes to turning stem cells into cartilage or bone cells. BMPs persuade the bone to create new bone cells in order to heal fracture sites or fill in bone defects. What are the results so far of studies with this new treatment?
Many of the studies done have been on lab animals (rats and rabbits). Only a few have been carried out on patients with ankle and foot problems. In both animals and humans, BMPs increase the area of new bone formed at fracture sites or where infection has eaten away at the bone leaving a defect (hole).
Scientists have even found a way to sustain the release of BMPs over time to create even more healing and bone fill-in. Use with high-risk patients who have poor bone healing from diabetes, high-energy injury, or who are immunosuppressed (immune system isn't working well) is under further study.
And finally, the third group of orthobiologics: platelet-derived growth factor (PDGF). You may be wondering how is this different from the first group we talked about: platelet-rich plasma? Platelet-derived growth factor is actually one of the specific platelet growth factors that make up part of the platelet-rich plasma.
It just happens that researchers have been able to take this one specific platelet growth factor and study it more closely for use in bone fractures. The clinical application of platelet-derived growth factor has been mostly with rats. But the findings so far suggest that it could be used to enhance bone healing in patients with poor bone healing of the foot and ankle.
The authors conclude that orthobiologics are here to stay and may become a routine part of surgery. But before that can happen, research is needed to make sure orthobiologics is safe and effective. Part of the work of scientists will be to find out which patients are the best candidates for this treatment as well as who doesn't need them.
With more orthobiologics being discovered and new ones being synthesized (manmade), the uses of these products will continue to expand over time. Their role is evident and important in enhancing healing and preventing infections and other complications. All of those effects will also improve patient satisfaction and reduce costs associated with surgeries for musculoskeletal problems.
Siddhant K. Mehta, et al. The Role of Growth Factors in Foot and Ankle Surgery. In Current Orthopaedic Practice. May/June 2010. Vol. 21. No. 3. Pp. 245-250.
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