Bone morphogenetic proteins for spinal fusion

Abstract

Background context: In 1965, Marshall Urist discovered that the extracellular matrix of bone contains the ability to induce new bone formation. This substance was later named bone morphogenetic protein (BMP). Since that time, BMPs have been extensively studied. Molecular clones have since been characterized and expressed as complementary DNAs (cDNAs). BMPs have recently been used in a multitude of mammalian clinical studies, including many recent human studies, for the purpose of evaluating their function in bone healing and spinal arthrodesis. BMPs are currently the most effective substitute available for bone graft as a means to eliminate the morbidity of iliac crest bone graft harvest and increase the rate of successful spinal arthrodesis.

Purpose: The purpose of this article is to review the history and recent advancements in the use of BMPs in spinal arthrodesis models, as well as discuss the possible future use of BMPs in this clinical setting.

Study design/setting: The setting of this review article is centered on classic and recent literature of BMPs with emphasis on anterior as well as posterolateral spinal arthrodesis.

Methods: The classic and recent primary literature about BMPS and their clinical use in human and nonhuman mammals for spinal fusion was reviewed. Special emphasis is placed on animal and human studies of both recombinant human bone morphogenetic protein-2 (rhBMP-2) and recombinant human osteogenic protein-1 (rhOP-1, rhBMP-7).

Results: BMPs are able to promote solid fusion in the spine in both the anterior and the posterolateral environments in animal studies and early human trials. Human trials to date have also shown an acceptable safety profile with the clinical use of these proteins.

Conclusions: Animal studies and early human trials of BMPs support the ability of these growth factors to enhance or replace autograft bone for spinal arthrodesis. Studies have shown this promotion of fusion in both the anterior interbody and the posterolateral environments. Future use of these factors is likely to continue to expand in clinical as well as research arenas.