Risk of Osteosarcoma in Dogs After Open Fracture Fixation

ObjectiveTo critically evaluate whether open fracture fixation is a significant risk factor for latent osteosarcoma development. Study DesignCase-control study. Sample PopulationDogs undergoing open fracture repair and dogs diagnosed with osteosarcoma. MethodsRecords were retrieved from the Veterinary Medical Database VMDB (1970-2000) for dogs undergoing surgical repair of a fracture and dogs diagnosed with osteosarcoma. Dogs with open reduction of joint luxation, dogs diagnosed with bacterial cystitis, and dogs diagnosed with urinary bladder transitional cell carcinoma (UBTCC) were queried as comparison populations. Relative risk for osteosarcoma development was determined. ResultsFrom a population of 19,041 fractures treated surgically, 15 of those dogs subsequently appeared in the VMDB with osteosarcoma affecting the same bone. The relative risk of a fracture repair and associated orthopedic implants and osteosarcoma occurrence was equivalent to the relative risk of open joint reduction and osteosarcoma occurrence (95% confidence interval; 0.998-1.00). The relative risk of having bacterial cystitis and appearing again in the VMDB with UBTCC was higher than the risk of open fracture repair and a subsequent diagnosis of osteosarcoma (P<.02). ConclusionThe incidence of fracture-related osteosarcoma may be significantly less than previously estimated based on cases queried from the VMDB. Although possible cases of implant-associated osteosarcoma were identified, their occurrence was rare. Elective implant removal for the purpose of reducing the risk of osteosarcoma after fracture repair may not be warranted and merits further investigation.