In Brief:
Healos (DePuy Spine, Inc., Raynham, MA)/recombinant human growth and differentiation factor-5 (rhGDF-5) is being developed as a potential bone graft substitute. Single-level intertransverse process fusions were performed in New Zealand white rabbits with autograft, Healos carrier alone, and Healos with 1 of 3 doses of rhGDF-5. Manual palpation revealed fusion rates for autograft of 38%, Healos alone of 0%, and each of the Healos/rhGDF-5 groups of 100%.