Pre-clinical evaluation of bone allograft toughened with a novel sterilization method: An in vivo rabbit study

Bone allografts often undergo γ-irradiation sterilization to decrease infection risk. However this consequently degrades bone collagen and makes the allograft brittle. Our laboratory has previously found that pre-treatment with ribose ex vivo protects the bone. However, it remains unclear whether or not ribose-treated γ-irradiated allografts are able to unite and remodel in vivo. Using New Zealand White rabbits (NZWr), we aimed to evaluate if ribose-treated allografts can unite with host bone (compared to untreated (fresh-frozen) and conventionally-irradiated allografts). A critically-sized defect was created in the radii of NZWr and reconstructed with allografts fixed with an intramedullary Kirschner wire. Healing and union were assessed at 2, 6, and 12 weeks post operation, with radiographs, µCT, static and dynamic histomorphometry, backscatter electron microscopy, and torsion testing. Intramedullary fixation achieved stable reconstructions and bony union in all groups and no differences were found in the radiographic and biomechanical parameters tested. Interestingly, γ-irradiated allografts had significantly less bone volume due to evident resorption of the grafts. In contrast, ribose pre-treatment protected γ-irradiated allografts from this bone loss, with results similar to the fresh frozen controls. In conclusion, ribose-pretreated γ-irradiated allografts were able to unite in vivo. In addition to achieving bony union with host bone, ribose pre-treatment may protect against allograft resorption. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res.