So what makes a good bone graft? All bone grafts are judged on three elements: osteoconductive scaffolding, osteoinductive growth factors, and the ability to incorporate with osteogenetic progenitor cells found in the human body. Though the terms may be difficult, the concept is relatively simple. These elements have been successfully achieved by the use of a particular graft taken from a patient’s own body.
Currently there is only one bone graft available that has been proven to meet all three elements. rhBMP2, or INFUSE® Bone Graft not only utilizes an osteoconductive scaffold, contains an effective level of BMP to be osteoinductive and initiates the process of bone formation, but also does not require any second procedures. INFUSE® Bone Graft does not need autograft or bone marrow aspirate.
The use of rhBMP-2 is still in an experimental stage. Spine surgeons have recently integrated INFUSE into their surgical repertoire as a surgical treatment option for patients suffering from degenerative disc disease.
The Spine Institute is currently engaged in the randomized clinical research study of the spinal implant device which consists of three components: (1) recombinant human bone morphogenetic protein-2 (rhBMP-2) which is soaked into (2) compression resistant matrix (CRM) and used with (3) the CD HORIZON® Spinal System. BMP-2 is a human protein.
Bone Morphogenetic Protein – 2, (BMP – 2), is a specific protein that has been clinically proven to stimulate bone growth. BMP-2 is found in trace amounts in human bone, but the limited supply of human donor bones precludes its extraction as an option. To solve this problem of finite supply, a recombinant version of naturally occurring BMP – 2 is manufactured using molecular biology techniques. The result is Recombinant Human Bone Morphogenetic Protein – 2, or rhBMP – 2.
Instead of using bone harvested from other parts of the patient’s body to generate bone growth in the spine, doctors insert rhBMP-2 between two or more vertebrae. This insertion induces bone growth and causes the vertebrae to fuse together, re-establishing spinal stability and alleviating pain caused by pressure on the nerves.
The “gold standard” of all bone grafts, has been a graft surgically removed from the iliac crest (hip area) of the patient about to have spinal fusion surgery. This bone graft is called an “autograft.” The problem with an autograft, is the procedure needed to access the bone and remove it, can cause complications of its own. Studies show an increased operative time, increased patient recovery time, and chronic pain at the location where the bone graft was taken as common complications of this procedure. Also, not everyone has bone suitable for use during surgery. A patient suffering from osteoporosis or who smokes is typically not a good candidate for autograft fusions. Because of these problems with autograft many physicians and researchers have tried to find or manufacture options that hold up to the high standards of autograft, without the complications.
Bone Marrow Aspirate
The problems and complications that occur when using bone marrow aspirate are similar to those that occur with autograft taken from the iliac crest. According to the National Institutes of Health, most patients complain of pain during this procedure. Besides pain, bleeding is the most common complication, and bruising at the donor site can also occur. According to the May 2002 supplement of Orthopedics, no human studies have currently been performed to test the osteoinductive properties of bone marrow aspirate.