Iron Chelators Augment Large Osteochondral Allograft Osseointegration in a Preclinical Canine Model

OBJECTIVES: Osteochondral allograft transplantation (OCAT) can be a successful joint restoration treatment option for large post-traumatic articular defects but is still associated with significant revision and failure rates. Despite recent advances that have improved OCAT success, insufficient osteochondral allograft (OCA) osseointegration remains a major cause of failure. Deferoxamine (DFO) is an effective angiogenic and osteo-anabolic iron chelator that consistently promotes bone neovascularization and regeneration. This study was designed to investigate local delivery of DFO for augmenting OCA osseointegration using a preclinical canine model for OCAT in the knee and hip as commonly affected joints. METHODS: On Institutional Animal Care and Use Committee (IACUC) approval, 12 purpose-bred dogs underwent OCAT of the femoral head or femoral condyles with DFO or DFO-free (controls) microspheres in recipient sites. OCA revascularization, cellular repopulation, and integration were evaluated based on functional, diagnostic imaging, microcomputed tomography, histology, and immunohistochemistry outcome measures. RESULTS: Local delivery of DFO into OCAT recipient sites was associated with maintained or improved joint function, superior radiographic appearance, significantly greater trabecular thickness, higher bone volume, and new bone ingrowth compared with DFO-free controls. CONCLUSION: OCA osseointegration is dependent on cellular repopulation and neovascularization, resulting in new bone ingrowth through creeping substitution, and insufficient osseointegration with resorption and subsidence of the OCA remains a major cause of failure after transplantation. The results of this study suggest that local delivery of DFO using a controlled microsphere release system may reduce resorption and improve revascularization and cellular repopulation to increase new bone ingrowth, potentially expediting OCA osseointegration after transplantation.