Experimental spinal fusion with recombinant human bone morphogenetic protein-2

Area of Science:

• Orthopedics
• Spinal Fusion
• Biomaterials

Background:

• Autogenous bone graft is standard for spinal arthrodesis but has complication rates of 25-30%.
• Bone graft substitutes and osteoinductive factors like bone morphogenetic proteins are being investigated.
• Recombinant human bone morphogenetic protein-2 (rhBMP-2) has shown success in generating bone in other animal models.

Purpose of the Study:

• To compare different dosages and carriers of rhBMP-2.
• To evaluate rhBMP-2 efficacy as a bone graft substitute for lumbar intertransverse process fusion.
• To validate findings in a rabbit posterolateral spinal fusion model.

Main Methods:

• Posterolateral intertransverse process arthrodeses performed at L5-L6 in 56 rabbits.
• rhBMP-2 or autogenous bone graft used for fusion.
• Assessment via manual palpation, radiography, histology, and biomechanic testing at 4 or 5 weeks.

Main Results:

• 100% of rhBMP-2 groups achieved solid fusion; only 42% of autograft controls did.
• Higher rhBMP-2 dose showed more mature fusion with greater trabecular bone.
• rhBMP-2 in collagen carrier resulted in more homogeneous fusions.
• rhBMP-2 fusions were biomechanically stronger and stiffer than autograft fusions.

Conclusions:

• rhBMP-2 reliably achieved lumbar intertransverse process fusion in the rabbit model.
• rhBMP-2 demonstrated superior bone formation, consolidation, and remodeling compared to autogenous bone graft.
• Fusions created with rhBMP-2 exhibited enhanced biomechanical strength and stiffness.