Arthur A. Gertzman

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 μm) 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.

The Effect of Cold Gamma Radiation Sterilisation on the Properties of Demineralised Bone Matrix

Demineralised bone in a viscous hyaluronan carrier was processed at sterilising and sub-sterilising doses of gamma radiation (10.2, 17.2 and 29.5 kGy). The pH, viscosity and osteoinductivity were measured. Osteoinductivity (OI) measured by implantation in an athymic (nude) mouse demonstrated significant loss at a dose of 17.2 kGy; OI scores declined 53% (p = 0.024). Viscosity also declined with increasing radiation dose. pH was unaffected.