Limb-sparing resection of musculoskeletal tumors has been well-demonstrated to have similar oncologic outcomes to amputation. However, large skeletal defects which are the result of such resections remain a challenge to reconstruct in a way that preserves function of the limb. Current options include: Irradiation and replacement of the affected bone; Massive osteochondral allograft; Endoprosthetic reconstruction; Vascularized bone autograft reconstruction. Patients with sarcomas, whether human or small animal, are often young and will subject their reconstructed limbs to high functional demands. For this reason, there is a premium on durability of reconstruction. Because endoprosthetic reconstructions are only as durable as the materials composing the endoprosthesis, they are subject to mechanical failure as well as failure to integrate into host bone. Allograft and irradiated bone are not living tissue and therefore are slowly incorporated into the host skeleton by a process known as "creeping substitution" - a process of simultaneous osteoclastic and osteogenic activity. This gradual process weakens these grafts and renders them particularly susceptible to nonunion, fracture, and infection.
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