Discussion of the use of bone morphogenic protein in your spinal fusion is appropriate and a second opinion may help to determine if it should be utilized.
Bone morphogenic proteins are responsible for the growth and differentiation of bone-forming cells. They form a large family of approximately 17 discrete proteins. Two of the families are available as recombinant human molecules (rhBMP-2 and rhBMP-7) and have been incorporated into commercial products. They are used to induce bone deposition in a range of anatomical sites including long bones (femur and tibia) and the spine. While initially approved by regulatory authorities for treatment of tibia fractures that were slow to heal, the US FDA, in 2004, extended their use to fusion of lumbar vertebrae. In the years that followed, multiple studies have appeared in the literature supporting the use of BMPs in lumbar spine fusion surgery. To date, claims that BMPs can act as bone graft replacements (in other words, allowing your surgeon to avoid having to harvest autogenous bone graft from your hip) has been favorable. Of the products presently being sold, more evidence is available for fusion of spinal vertebrae with products containing BMP-2 (Infuse) than BMP-7 (OP-1 putty). The evidence does not support claims, nor are the manufactures making them, that recombinant human BMP, when compared to autograft obtained from the patient’s hip, are superior in achieving bone fusion. However, the pain and complications associated with harvesting bone are removed, and this, in and of itself, is a considerable advantage.
Bone morphogenic proteins appear to be safe provided they are used appropriately and placed accurately within the spinal column during spinal fusion surgery. The evidence in the peer-reviewed medical literature indicates that BMPs were at least as effective as autogenous bone graft harvested from the patient’s iliac crest in terms of achieving stable spinal fusion. The benefits of bone morphogenic proteins compared to autogenous iliac crest harvested bone graft included the decrease in operating room time, blood loss, and morbidity due to the avoidance of the additional procedure to harvest the iliac crest bone graft. None of the studies using BMP-2 or BMP-7 documented any adverse systemic effects occurring as a result of their use.
Definitive patient selection criteria for the use of BMP products in spinal fusion have not been established. However, there is sufficient evidence to support the use of BMP-2 in a collagen sponge in combination with supportive implant devices for single-level spinal fusion surgery.
The indications for the usage of BMPs, as defined by the FDA, were very specific, and, in summary, include using BMPs only when in combination within intervertebral body fusion device (cage) for sing-level fusion after a failure of more than six months of non-operative treatment. BMPs should be utilized only in skeletally mature individuals and, currently, are confined to use in one-level fusions. Despite these limited indications as set forth by the FDA, the use of bone morphogenic proteins has become a common occurrence in most hospitals where spine surgery is performed. As surgeons have become more experienced in their utilization of BMPs, we have seen the usage of BMPs extended well beyond the recommended indications. In our opinion, complications can occur when the indications for the use of BMP are extended inappropriately. As such, while we believe that the use of BMP is appropriate in many instances, the potential for complications must also be considered. For this reason, discussion of the use of bone morphogenic protein in your spinal fusion is appropriate, and a second opinion may help to determine if its usage is appropriate in your specific case.