Background
Therapeutic augmentation of fracture site angiogenesis with Deferoxamine (DFO) has proven to increase vascularity, callus size and mineralization in long-bone fracture models. We posit that the addition of DFO would enhance pathological fracture healing in the setting of radiotherapy in a model where non-unions are the most common outcome.
Methods
Sprague-Dawley rats (n = 35) were divided into 3 groups. Fracture (Fx), radiated fracture (XFx) and radiated fracture + DFO (XFxDFO). Groups XFx and XFxDFO received a human equivalent dose of radiotherapy (7 Gy/day × 5 days = 35 Gy) 2 weeks prior to mandibular osteotomy and external fixation. The XFxDFO group received injections of DFO into the fracture callus after surgery. Following a 40-day healing period, mandibles were dissected, clinically assessed for bony-union, imaged with Micro-CT, and tension tested to failure.
Results
Compared to radiated fractures, metrics of callus size, mineralization and strength in DFO treated mandibles were significantly increased. These metrics were restored to a level demonstrating no statistical difference from control fractures. In addition we observed an increased rate of achieving bony unions in the XFxDFO treated group when compared to XFx (67% vs. 20% respectively).
Conclusions
Our data demonstrate near total restoration of callus size, mineralization, and biomechanical strength, as well as a 3-fold increase in the rate of union with the use of DFO. Our results suggest that the administration of DFO may have the potential for clinical translation as a new treatment paradigm for radiation induced pathologic fractures.
Level of Evidence
Animal study, not gradable for level of evidence.