Spinal fusion with recombinant human growth and differentiation factor-5 combined with a mineralized collagen matrix

The availability of recombinant osteoinductive growth factors and new osteo conductive matrices offers an alternative to the use of autogenous bone (au tograft) for grafting indications. This study evaluates the bone-forming ac tivity of a mineralized collagen matrix combined with recombinant human gro wth and differentiation factor-5 in a rabbit posterolateral spinal fusion m odel. The activity of three distinct matrix-growth factor formulations is a ssessed by radiographic, histologic, and mechanical strength methods. Resul ts show that the radiographic density, histologic quality, and mechanical s trength of fusion at 12 weeks post-treatment rank consistently within the t reatment groups. Optimal formulations are shown to perform similar to autog raft in both the rate and strength of fusion. Fusion rates as high as 80% a re observed within specific matrix/growth factor formulations. The average biomechanical strength of treated motion segments in the most efficacious f ormulation is 82% higher than that obtained with autograft, although this d ifference is not statistically significant. The fusion mass formed in respo nse to matrix/growth factor formulations is composed of normal trabecular b one with a thin outer cortical plate and modest hematopoietic bone marrow. These results demonstrate that the combination of a mineralized collagen ma trix with recombinant human growth and differentiation factor-5 maximizes t he inherent conductive and inductive properties of each component, respecti vely, to provide an effective alternative to autograft for bone grafting pr ocedures. Anat Rec 263: 388-395,2001. (C) 2001 Wiley-Liss, Inc.