The spine journal : official journal of the North American Spine Society
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The commercially available growth factor recombinant bone morphogenic protein-2 (rhBMP-2) used in spinal fusion has been associated with numerous adverse reactions, including inflammatory reactions in soft tissue, heterotopic bone formation, radiculitis, osteolysis, and cage or graft subsidence. The original Food and Drug Administration Summary of anterior lumbar interbody fusion (ALIF) reported 12 retrograde ejaculation (RE) events (8%) in the rhBMP-2 groups compared with (1.4%) in the control group. It had been debated whether this finding was related to rhBMP-2 use. ⋯ This study confirms previous reports of a higher rate of RE in ALIF procedures using rhBMP-2. This may be an important consideration in subjects concerned with sterility after surgery.
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Recent studies have demonstrated cases of adjacent vertebral body osteolysis when assessing the effect of bone morphogenetic protein (BMP) on fusion rates. However, no study to date has evaluated the course of osteolysis at different periods. ⋯ The rate of osteolysis decreased at 1 year compared with 3 to 6 months, but only 24% of the vertebral bodies with evidence of osteolysis at 3 to 6 months completely resolved by 1 year.
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Potential complications related to ectopic bone formation, as seen with transforaminal lumbar interbody fusion, have always been a concern with the use of bone morphogenetic proteins (BMPs). Although less clearly anticipated, complications related to the proinflammatory effects of recombinant human bone morphogenetic protein-2 (rhBMP-2), such as swelling and edema in the cervical spine, have been observed as well. Until recently, risks related to intradural exposure to BMP have not been widely considered. However, a recent animal study reports "in the presence of a SCI and/or dural tear, rhBMP-2 diffuses intrathecally and activates a signaling cascade in all major CNS cell types, which may increase glial scarring and impact neurologic recovery." Although this study was conducted at the spinal cord level, the observation generates obvious concerns for the much more common scenario of a dural tear associated with lumbar decompression and fusion. ⋯ The data suggests fairly convincingly that the presence of a repairable dural tear is not necessarily an impediment to the use of rhBMP-2 in posterolateral fusion. Further studies are needed to address the less common clinical scenario of BMP use in conjunction with spinal cord injury, as studied in the animal model that prompted this investigation. Finally, avoidance of BMP use may still be prudent in the setting of an unrepairable dural tear.
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Using bone morphogenic protein (BMP) to augment fusion in spine surgery is widespread and lends itself in particular to minimally invasive lumbar fusion, where the surface area for fusion is significantly less than the equivalent open procedure. ⋯ The use of BMP with autograft in the disc space during minimally invasive lumbar interbody fusion is associated with a high rate of early fusion. Even with very low-dose BMP used in this study, complications related to BMP usage were not avoided completely.