Osteosarcoma of the proximal tibia in a dog 6 years after tibial tuberosity advancement.

A 9-year-old spayed female Cane Corso dog was presented with a 1-week history of an acute right hind limb non-weight-bearing lameness. Six years previously, a right tibial tuberosity advancement (TTA) procedure had been performed. Orthogonal radiographs of the right pelvic limb taken before presentation revealed a comminuted displaced mid-diaphyseal tibial fracture. An aggressive bone lesion with osteolysis and periosteal reaction of the proximal tibia were evident that were most consistent with a primary bone tumor. The owner elected to have the dog euthanized. After euthanasia a fine-needle aspirate of the right proximal tibia was submitted for clinical pathology. Cytology and alkaline phosphatase staining of the fine-needle aspirate were consistent with osteosarcoma. Key clinical message: To the authors' knowledge, this is only the second reported case of osteosarcoma at the site of a TTA. Implantassociated osteosarcoma has been associated with tibial plateau levelling osteotomy (TPLO) and fracture repair.