Bone Graft Surgery : Autograft & Biodynamic Products
Bone Graft Materials
For Spinal Fusion procedures where bone needs to form between the vertebrae or the transverse or spinous processes, there are a few options available to Surgeons for this to take place.
The gold standard is to harvest the patient’s own bone marrow (Autograft) from the hip through a separate incision. This gives the highest quality bone and the highest chance of a fusion occurring. However the draw-backs are it is painful and patients complain more about the hip donor site wound than the operative wound itself in the neck or lower back etc.
Alternatives to the patient’s own bone marrow are to use local bone from the operative zone, but this is not as good quality and there may not be enough.
Allograft is bone donated by other patients to a designated “Bone Bank” where bone is sterilized, irradiated and ground up to manageable granules to be used in operations to form a fusion over time. Such donated bone may come from hip or knee joint procedures where some bone is removed from the patient.
The other option is to use purely synthetic “man-made” bony-like products that can act as “scaffolds” for the patient’s own bone to grow into them.
There are many products on the market but generally the fusion rates are slightly lower than Allograft.
Dr Pope prefers to use Allograft as the fusion rates are only slightly lower (a few %) than Autograft but there is no painful donor site.
The next few paragraphs are about products that can help promote and intensify the bone growth into the instrumented spinal operative zone and promote a solid fusion over the ensuing 9-18 months.
Bone Growth Factors
The term "growth factor" refers to a naturally occurring protein capable of stimulating cellular proliferation and cellular differentiation. Growth factors are important for regulating a variety of cellular processes. Growth factors typically act as signaling molecules between cells and involved in Neuromodulation. Hormones are an example of growth factors. Growth factors bind to specific receptors on the surface of their target cells. They often promote cell differentiation and maturation, which varies between growth factors. For example, bone morphogenic proteins stimulate bone cell differentiation, while vascular endothelial growth factors stimulate blood vessel differentiation.
Bone Morphogenetic Proteins (BMPs)
Certain bone morphogenetic proteins, or BMPs, have been studied for decades because of their remarkable ability to heal bone and eliminate the need for bone graft harvesting from the hip. Approximately 20 BMPs have been discovered, but only six appear capable of initiating bone growth. Of these, rhBMP-2 has been studied more than any other BMP and is FDA approved for use in certain spinal and tibial surgeries.
Naturally occurring BMP is found within the bone itself; however, it is only available in small amounts. To provide clinically useful and reproducible amounts of isolated, human BMP, it cannot be economically extracted from donor bone and must be manufactured (genetically engineered).
The preferred method for manufacturing rhBMP-2 is by a process called recombination. Scientists isolated the gene for one protein (BMP-2) from the bone tissue and used well-established molecular biology techniques to create genetically engineered cells. These cells then produce large quantities of rhBMP-2. A similar process is used to manufacture other proteins, like insulin. The recombinant form of rhBMP-2 is identical to the natural form in both its chemistry and its ability to heal bone.
During surgery, rhBMP-2 is soaked onto a sponge that is designed to resorb, or disappear, over time. As the sponge dissolves, the rhBMP-2 stimulates the cells to produce new bone and ultimately, to heal. After a few weeks, the rhBMP-2 also goes away, but it has completed its task to initiate the normal bone healing process. In the spine, the BMP grows bone in the disc space to join or fuse the vertebrae and stabilize the spine. In certain tibial fractures, rhBMP-2 has been shown to help heal broken bones.
Medtronic INFUSE® Bone Graft
INFUSE® Bone Graft by Medtronic contains a bone growth protein used in an Anterior Lumbar Interbody Fusion (ALIF) procedure in combination with a metallic cage implant. Using INFUSE® Bone Graft helps reduce the pain and complications associated with treating degenerative disc disease (DDD) by eliminating a second surgery to harvest bone from a patient's own hip (autograft) for transplantation to the spine, as is done in traditional spinal fusion procedures.
The active ingredient in INFUSE® Bone Graft is recombinant human bone morphogenetic protein-2 (rhBMP-2). Bone morphogenetic protein is a manufactured version of a natural protein found in small quantities in the body. The purpose of the protein is to stimulate bone formation.
INFUSE® Bone Graft is the first autograft replacement approved for use in spinal fusion. Spinal fusion is a surgical method of treating degenerative disc disease after conservative treatments have failed. The procedure stabilizes the spine by fusing two adjacent vertebrae together and helps to alleviate the back pain caused by a degenerated disc in the spine.
To use INFUSE® Bone Graft, surgeons mix the rhBMP-2 powder with sterile water and then apply it to collagen sponges. The sponges are inserted inside a pair of metallic cages, which are then implanted between the vertebrae. The thimble-like cages stabilize the spine while fusion occurs and maintain the proper height between the vertebrae.
Courtesy of: http://www.infusebonegraft.com/spine_index.html
Stryker OP-1
OP-1 is a bone morphogenetic protein (BMP) that is naturally found in the human body. This unique protein has the ability to transform cells in the body to become new bone and ultimately repair fractures.
Dural Substitutes
Durepair®~ Dura Regeneration Matrix by Medtronic
Common Usual or Classification Name: Dura Substitute
Description: The Durepair Dura Regeneration Matrix is a collagen implant for the repair of defects in the dura mater. Durepair is supplied sterile in sheet form in a variety of sizes to be trimmed and sutured by the surgeon to meet the individual patient's needs.
Intended Use: Durepair is a dura substitute for the repair of the dura mater (cranial or spinal).
