Osteosarcoma in a dog eight years after tibial plateau leveling osteotomy with an angle stable implant

An 11-year-old, 41-kg female spayed mixed-breed dog was examined for a chronic left hind limb lameness, with swelling of the proximal left tibia. A tibial plateau leveling osteotomy (TPLO) using an angle stable implant had been performed 8 years earlier at the site. Initial radiography showed mild degenerative signs in the stifle joint and osteolytic lesions in the proximal tibial metaphysis. Three weeks later, the clinical and radiographic changes had worsened. A transition from a moth-eaten pattern to permeative bone lysis was radiographically evident, along with an extensive increase of soft tissue swelling. Ultrasonographically-guided fine needle aspiration of the epiperiosteal tissue and lymph nodes, CT with pre-and post-contrast scans, and an incisional biopsy were performed. The radiographic and CT findings were consistent with an aggressive and monostotic bone lesion at the site of previous TPLO. The cytology and histology confirmed the diagnosis of an osteosarcoma (OSA) with a chondroid differentiation. Three months after a palliative hind limb amputation, the dog was euthanased. CONCLUSION We believe that this is the first report of implant-related OSA at the site of a previous TPLO with a new generation angle stable implant