Healos/Recombinant Human Growth and Differentiation Factor-5 Induces Posterolateral Lumbar Fusion in a New Zealand White Rabbit Model

Abstract

In Brief Study Design. Posterolateral lumbar spine fusions in New Zealand white rabbits. Objective. To evaluate the efficacy of recombinant human growth and differentiation factor-5 (rhGDF-5) lyophilized to a Healos carrier (cross-linked type I collagen with hydroxyapatite coating; DePuy Spine, Inc., Raynham, MA) in inducing fusion. Summary of Background Data. Bone graft substitutes have become an area of considerable interest. rhGDF-5 is one such product. Limited lumbar preclinical studies have been performed with this product. Methods. Single-level, intertransverse process fusions were performed in 67 rabbits using iliac crest autograft (n = 13), Healos alone (n = 13), or 0.5, 1.0, or 1.5 mg/cc rhGDF-5 lyophilized to Healos (n = 13 per group). At 8 weeks, the rabbits were euthanized. Fusion masses were assessed. Results. There were 2 animals (3%) lost to complication. Manual palpation revealed fusion rates for autograft of 38% (5/13), Healos alone of 0% (0/13), and each of the Healos/rhGDF-5 groups of 100% (13/13). Histologic analyses were 95% sensitive and 95% specific for confirming fusion. Histologic differences were found among the treatment groups. Conclusions. In this rabbit fusion model, Healos/rhGDF-5 induced fusion in 100% of the rabbits studied. This rate was significantly higher than the fusion rate induced by autograft (38%). Overall, these results support continued research of Healos/rhGDF-5 as a potential bone graft alternative. 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%.