Study design: Six groups of 10 animals underwent single level, uninstrumented posterolateral lumbar fusions. Graft sites were implanted with autologous bone, autologous bone plus B2A coated granules with concentrations of 0-, 50-, 100-, or 300 microg/mL, or no graft material. Explanted motion segments were analyzed by Faxitron radiographs, computerized tomography (CT), manual palpation, and histology.
Objective: The synthetic peptide B2A2-K-NS (B2A) was evaluated as a novel agent for augmenting spinal fusion in a posterolateral, noninstrumented rabbit lumbar spine fusion model.
Summary of background data: There have been many efforts to increase the rate of posterolateral spinal fusion while, at the same time minimizing, use of autologous bone with its inherent harvest morbidity.
Methods: B2A coated ceramic granules (0-, 50-, 100-, and 300 microg/mL) were mixed 1:1 with autogenous iliac crest bone and implanted. Autogenous bone alone was used as a positive control. Fusion was assessed at 6 weeks via radiographs and manual palpation. These results were confirmed with histology and CT.
Results: Fusion results from palpation and radiographic evaluations were similar. CT and histology confirmed bridging bone across the transverse processes for fused spines. The highest fusion rates were observed in the 100 mug B2A/mL group-89% in comparison to 33% for uncoated granules (0 microg B2A/mL) and 63% for autograft alone. These differences were statistically significant.
Conclusion: All investigated B2A concentrations demonstrated increased fusion rates. Fusion masses resulting from the implantation of 100 mug B2A/mL granules demonstrated new woven bone: fused to the transverse processes, within granule pores, bridging bone across the transverse processes, and bridging residual bone graft and granules. It was concluded that each investigated concentration of B2A coated granules in a 1:1 mixture with autograft increased fusion rates in comparison to controls in this rabbit model.