Systematic Review on Recombinant Human Bone Morphogenetic Protein-2 Versus Autologous Iliac Crest Bone Graft in Lumbar Spine Fusion

Abstract

SUMMARY L umbar spinal fusion surgery with autogenous iliac crest bone graft (ICBG) developed over several decades and became the gold standard surgical procedure. However, there are many complications associated with use of autograft in lumbar fusion include; donor-site morbidity (donor site-pain, hematoma, infections, fracture) pseudoarthrosis, prolongs the operating time, increase operative blood loss and limited amount of bone can be harvested. So, to avoid and prevent the previous complications, bone graft substitutes were used as alternative to autogenous iliac crest bone graft. There are several types of bone graft substitutes, Bone Morphogenetic Proteins (BMPs) are possible substitute for autogenous bone graft. The Bone morphogenetic proteins was discovered by Dr. Marshall Urist in 1965s, he observed the extracelullar matrix of bone can induce new bone growth, but the protein responsible for bone induction remained unknown until the purification and sequence of bovine BMP-3 and cloning of human BMP-2 the late 1980s. Recombinant human bone morphogenetic protien-2 (rhBMP2) is growth factor belongs to the transforming growth factor-B (TFG-B) superfamily, low molecular weight transmembrane glycoprotien bind to membrane–bound receptors resulting in a cascade of intracellular events that affect the expression of genes encoding for cell division and protein synthesis. RhBMP-2 had significant osteogenic properties, are able to stimulate proliferation and differentiation of osteoblasts that direct bone formation. rhBMP-2are naturally exist within the bone matrix and work as regulator of chemotaxis, stimulation of extracellular matrix synthesis, also play a role in regulation of bone volume and healing of bone after fracture. Can be extracted and purified from bone or synthesized using recombinant genetic techniques. Recombinant human bone morphogenetic protien-2 are soluble require use of carrier. The carriers plays important role in delivery of rhBMP-2 to the site of fusion, maintain it locally in an effective concentration, prevent their diffusion away to another sites where unfavorable bone could be formation and providing an enviroment suitable for fusion with host bone. Common carriers include: an absorbable type I collagen sponge (ACS). Ceramics (hydroxy apatite, tricalcium phosphate), a compression resistant matrix (CRM) and synthetic polymers (polylactic acid, polyglycolic acid). The rhBMP-2 and carrier may be inserted to the site of fusion via delivery system (cages) which provide mechanical support. In 2002, the U. S. Food and Drug Administration (FDA) approved rhBMP-2 delivered on a collagen sponge carrier (INFUSE Bone Graft, Medtronic Sofamor Danek, Memphis, TN) as bone graft substitute in conjunction with a device implant LT-CAGE® Lumbar Tapered Fusion Device (Medtronic Spinal and Biologics, Memphis, TN). For single level of anterior lumbar interbody fusion (ALIF). In 2003, the FDA approved the use of rhBMP-2 with another implant (interfix). Then the FDA approved use of rhBMP-2 for the repair of symptomatic posterolateral lumbar spine pseudoarthrosis. So we conducted this systematic review to compare the outcomes between recombinant human bone morphogenetic protien-2 (rhBMP2) and autogenous iliac crest bone graft (ICBG) in lumbar spinal fusion surgery.