The focus of current management of soft tissue sarcoma on limb preservation often necessitates that patients undergo multimodal treatment, including both surgery and external beam radiotherapy. Pathologic fracture is a serious, late complication of radiotherapy. In patients who have also undergone wide excision of soft tissue sarcoma, nonunion rates of 80–90% persist despite optimal internal fixationMany sequelae of the treatments for soft tissue sarcoma exhibit the potential to perpetuate failure of bony union. Limb salvage surgery is associated with extensive periosteal excision, disruption of vascular supply and eradication of local osteoprogenitor cells. External beam radiotherapy leads to obliterative endarteritis, decreased osteoblast proliferation and reduction in bone matrix production. We hypothesize that the combination of radiotherapy and surgical periosteal stripping leads to greater impairment in the fracture repair process than either intervention alone will produce. We developed a method for creating a reproducible, low energy, simple femoral fracture in an animal model designed to proceed to nonunion. Female Wistar, retired breeder rats were separated into four treatment groups of 18 animals each: control, radiotherapy, surgery and combination radiotherapy and surgery. Animals were then further randomized to temporal end-points of 21, 28 and 35 days post-fracture. Designated animals first underwent external beam radiotherapy, followed by surgical stripping of the periosteum three weeks later and femoral fracture with fixation after another three weeks. Animals were sacrificed at their randomly assigned end-points.Purpose
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