Canine osteosarcoma associated with orthopaedic procedures

Introduction Aim of the study was to evaluate a series of 5 canine osteosarcoma cases that arose in sites previously subjected to orthopaedic procedures is described. To our knowledge, the relevant veterinary literature is limited to single case reports.
Methods and results Four cases were initially presented for evaluation of a fracture and one requiring hip arthroplasty, were subjected to the appropriate treatment that in all cases included an orthopaedic procedure, and all later developed tumours in the sites subjected to the orthopaedic procedures. All tumours were histologically confirmed to be osteosarcomas and all but the arthroplasty one arose in the diaphysis of the bone concerned. Two tumours developed adjacent to the orthopaedic plate that was left in place; one in the right femur with metastases to the right tibia and vertebrae, while the other occurred adjacent to the plate 13 years after it was used for a fracture of right tibia. One femoral tumour developed around an orthopaedic wire left in place. One osteosarcoma developed in the right proximal femur 6 years after excision hip arthroplasty. An ulnar osteosarcoma developed 6 years after a fracture was treated by external fixation with a cast.
Conclusions The development of osteosarcoma in sites subjected to orthopaedic procedures may be due to a range of factors, including poor healing possibly inducing increased osteoblastic activity, chronic inflammation or the possibility that the orthopaedic devices left in place or their corroded by-products have some carcinogenic effect. Given the large number of orthopaedic procedures routinely performed in dogs, the development of osteosarcoma in association with these procedures may also be coincidental in some cases.