Radiographic, Histologic and Mechanical Comparison of NanoFUSE® DBM and a Bioactive Glass in a Rabbit Spinal Fusion Model

Autologous bone has long been the gold standard for bone void fillers. However, the limited supply and morbidity associated with using autologous graft material has led to the development of many different bone graft substitutes. The use of bone graft extenders has become an essential component in a number of orthopedic applications including spinal fusion. This study compares the ability of NanoFUSE® DBM and a bioactive glass product (NovaBone Putty®) to induce spinal fusion in a rabbit model. NanoFUSE® DBM is a combination of allogeneic human bone and bioactive glass. NanoFUSE® DBM alone, and in combination with autograft, and NovaBone Putty®, were implanted in the posterior lateral intertransverse process region of the rabbit spine. The spines were evaluated for fusion at 4, 8, 12, and 24 weeks for fusion of the L4-L5 transverse processes using a total of 64 skeletally mature rabbits. Samples were evaluated by manual palpation, radiographically, histologically, and by mechanical testing. Radiographical, histological, and palpation measurements demonstrated the ability of NanoFUSE® DBM to induce new bone formation. The material in combination with autograft performed as well as autograft alone with respect to new bone formation and bridging bone at all time points with the exception of four week radiographic analyses. In addition, the combination of allogeneic human bone and bioactive glass found in NanoFUSE® DBM was observed to be superior to the bioactive glass product NovaBone Putty® in this rabbit model of spinal fusion. This in vivo study demonstrates the DBM and bioactive glass combination, NanoFUSE® DBM, could be an effective bone graft extender in posterolateral spinal fusions.