Novel Endoprosthesis for Limb Sparing of Canine Distal Radius Osteosarcoma Patients: A Modular Approach

Distal radius osteosarcoma accounts for nearly 10% of all cancer-related maladies within the canine population. Traditional methods of treatment include amputation and/or chemotherapy. A major increase in survival rates (from 10% to 60%) with the combined use of these two techniques has now directed research towards saving the limbs of these patients. Massive cortical bone allografts, metal endoprosthesis and distraction osteogenesis are some of the available limb sparing approaches that have been investigated. Distraction osteogenesis requires surgeon expertise and significant post-operative intervention. Cortical allografts require the maintenance of a bone bank. Furthermore, they are associated with increased infection rates and ultimately result in amputation of the affected limb. Metal endoprostheses are a viable alternative to these methods. A metal endoprosthesis has previously been developed for limb sparing of distal radius osteosarcoma patients. However, a clinical trial of this device demonstrated failure rates of approximately 40%. The major causes of failure were screw pullout and shear failure of the proximal radius screws. A computational finite element study conducted in our laboratory corroborated these findings and provided critical information as regards to the structural causes of failure for these implants.