BMP-2 Identified as Risk Factor for Neurological Problems After Spinal Fusion Surgery

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spinal-fusion-surgery-nerve-injuryBMP-2, the bone morphogenetic protein closely related to Medtronic Infuse bone graft, is a factor for neurological deficits in patients who had certain spinal fusion surgeries, a recent study has found. Healio reports that Alexander Aichmair, MD, a spine research fellow at New York’s Hospital for Special Surgery, said in a presentation that several factors, including BMP-2 use, increased the risk of neurological deficits in patients who underwent lateral lumbar interbody fusion (LLIF) with a retroperitoneal approach.

“The level of fusion, multilevel lateral lumbar interbody fusion, female gender, as well as the use of bone morphogenetic protein-2 [BMP-2] were associated with a higher risk of developing a postoperative neurological deficit and pain,” Aichmair said.

Current research shows that the rate of postoperative neurological deficits ranges from 0.7% to 23% in patients who have undergone LLIF. The purpose of Aichmair’s study was to identify the risk factors for this complication, and whether or not the deficits were long-lasting or transient. Reseachers analyzed 451 people who underwent LLIF. The patients in this study had a degenerative spine with at least 6 months of follow-up after their surgery; they had no previous hisotry of thoracolumbar spine surgery.

The average age of the patient at surgery was 63 years, and they had an average follow-up period of 15 months. In total, 919 levels of the spine were treated; on average, two levels were treated per patient. According to Aichmair, the most commonly treated levels were L3-4 and L4-5.

An initial assessment was performed on all of the participants, and further analyses was conducted for subgroups in the study. The rates of motor deficits was 24.1 percent at the initial analysis, and the rate of sensory deficits was 17.3 percent. After removing patients who had neurological deficits preoperatively, the motor and sensory deficit rates were 3.2 and 9.3 percent, respectively. Eighty-seven patients who were followed for at least 18 months had rates of 2.3 percent for a persistent motor deficit, 9.6 percent for a sensory deficit and 5.8 percent for anterior thigh and groin pain, which was present during the last follow-up visit.

The researchers found that BMP-2 use, being female, surgeon experience, the L2-3 level and multilevel surgery were linked to a higher risk of postoperative neurological deficits and/or pain. The deficits were high after surgery, and generally transient in nature, Aichmair said.

Aichmair said that other findings confirm BMP-2 as a risk factor for neurological issues, including a matched cohort study he and his colleagues conducted comparing LLIF patients with and without BMP-2 use.

Medtronic Infuse is composed of recombinant human bone morphogenetic protein-2 (rhBMP-2). Infuse is an artificial bone graft used in spinal fusion surgeries and two types of dental surgery. It has become highly controversial due to reports that Medtronic-paid doctors hid side effects in studies; there has also been concern about complications that occur with the product when it is used off-label. Side effects associated with Infuse include nerve injuriy, cancer, male sterility and excess bone growth.