A Pilot Study Evaluating Sodium Hyaluronate as a Carrier For Freeze-dried Demineralized Bone Powder

Freeze-dried demineralized bone (FDDB) is widely used in orthopaedic and neurosurgery. However, it is difficult to deliver the FDDB by itself and surgeons have been seeking a convenient and easy-to-use form of FDDB. This study was designed to evaluate sodium hyaluronate (HA) as a carrier or delivery vehicle. HA is a viscous and biocompatible high molecular weight hydrogel. It was tested as a viscous carrier to facilitate the delivery of freeze-dried demineralized bone into a bony defect. The natural bone forming properties of FDDB were evaluated in an athymic mouse model and shown to be as active when dispersed in HA as compared to a saline control. Particle sizes in the range studied (125-850 microm) had no effect on FDDB efficacy. All exhibited active bone formation. Similarly, two different carrier viscosities were formulated to achieve both a malleable putty and a more flowable paste. These, too, both exhibited active bone formation. The use of a pH 7.4 buffer in the HA formulation gave optimum results in the model. Additional studies are underway to further evaluate the surgical efficacy of FDDB suspended in HA.