OsteoAMP May Be More Effective Than rhBMP for Spinal Fusion

Laird Harrison

October 24, 2013

SAN FRANCISCO — Allogeneic morphogenetic protein (OsteoAMP, Advanced Biologics, Carlsbad, California) may work better than recombinant human bone morphogenetic protein-2 (rhBMP-2) in spinal fusions, a new study shows.

"The superior fusion rate and the economic analysis suggest that OsteoAMP is a potentially more cost-effective and viable alternative to BMP-2," said Christopher Yeung, MD, a spine surgeon at Desert Institute for Spine Care in Phoenix, Arizona, and an advisor to Advanced Biologics.

Dr. Yeung presented the findings here at the Congress of Neurological Surgeons (CNS) 2013 Annual Meeting.

Complications ranging from erectile dysfunction to cancer have raised concerns about rhBMP in spinal fusion surgery. In addition, this growth factor is expensive.

These problems have stimulated interest in alternatives. OsteoAMP has allogeneic morphogeneic protein derived by Advanced Biologics' proprietary process, said Dr. Yeung.

"It's basically an allograft," he said. "However, during the processing technique instead of washing away and discarding all of the marrow products and cells they've found a way to get those growth factors and bind them to the allograft bone while they're harvesting it."

The material contains more than 500 times as much BMP-2 than traditional demineralized bone matrix and also includes several other growth factors in addition to BMP-2, he said. It comes in the form of granules, putty, compressible sponge, or structure.

This study looked retrospectively at 321 consecutive patients with 502 levels treated at 3 institutions with lateral lumbar interbody fusion (LLIF) or transforaminal lumbar interbody fusion (TLIF). Of these, 226 were treated with OsteoAMP and 95 with rhBMP-2.

An independent radiologist who was blinded to what growth factor was used assessed the fusions at intervals up to 18 months. The investigators defined fusion as radiographic evidence of bone bridging across endplates or from the endplates into the bone cages, or obliteration of the endplate or cage lucency in an immediate postoperative radiograph.

This analysis showed better and faster fusion for OsteoAMP, a difference that was statistically significant (P ≤ .01).

Table. Fusion Rates and Radiographic Complication Rates

Variable Fusion at 3 Months Fusion at 6 Months Fusion at 12 Months Fusion at 18 Months Osteolysis, Subsidence, Endplate Irregularity Exuberant/Ectopic Bone Formation
OsteoAMP (%) 18.6 59.7 93.3 98.9 4.9 5.3
rhBMP-2 (%) 10.5 39.3 83.5 90.1 10.5 24.2

 

Total time for fusion with OsteoAMP was 207.9 days, vs 333.9 days for rhBMP-2.

The rhBMP group showed more radiographic complications as well. It had 4 times the rate of ectopic bone formation, which was a statistically significant difference (P < .01). It also had twice the rate of osteolysis or subsidence, although this was not statistically significant (P = .06).

The average age of the OsteoAMP group, 60.0 years (±13.0), was slightly greater than the rhBMP-2 group's 54.3 years (±10.9), but a statistical analysis showed no correlation between age and time to fusion in either group.

Surgeons in both groups mixed the growth factors with some local autograft bone. Surgeons in about 58.4% of the OsteoAMP cases also used some bone marrow aspirate, but the investigators found no statistically significant difference between these patients and the other OsteoAMP patients (P ≥ .44).

The surgeons used about 2.5 cm3 of OsteoAMP per level versus 2.05 cm3 of rhBMP. But the cost per level is about $2500 for Infuse brand of rhBMP (BioHorizons) and a little over $500 for the OsteoAMP, said Dr. Yeung.

Dr. Yeung said a prospective trial was also being conducted to compare the 2 growth factor products.

The presentation sparked a lively discussion in the question-and-answer period. One person in the audience said he had done his own informal trial comparing OsteoAMP, BMP, and Trinity Evolution (an allograft of cancellous bone containing viable cells sold by Orthofix) and found OsteoAMP to be inferior.

Referring to Dr. Yeung's disclosure that he sits on the scientific advisory board for Advanced Biologics, another audience member called for a trial of OsteoAMP by someone not associated with the company.

Asked to comment, Mohammed Shamji, MD, an assistant professor of neurological surgery at the University of Toronto, Ontario, Canada, told Medscape Medical News that the topic of growth factors in spine surgery had become "really controversial."

He pointed out that this presentation did not include any data on the kind of complications that have raised the most concerns about rhBMP-2.

"This is the first report of superiority for OsteoAMP, and there is no mechanism put forth," he said. "This comprises some of the same molecules [as rhBMP-2] but the authors did not talk about how or whether this prevents the same complications."

Dr. Yeung is on the scientific advisory board for Advanced Biologics. Dr. Shamji has disclosed no relevant financial relationships.

Congress of Neurological Surgeons (CNS) 2013 Annual Meeting. Abstract #159. Presented October 22, 2013.

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