title: Bi-institutional retrospective cohort study evaluating the incidence of osteosarcoma following tibial plateau levelling osteotomy (2000-2009).
abstract: OBJECTIVE
  To evaluate the incidence and risk factors for occurrence of osteosarcoma (OSA) following tibial plateau levelling osteotomy (TPLO).
  
  
  METHODS
  Medical records of client-owned dogs that underwent consecutive TPLO procedures at two institutions were retrospectively reviewed. Referring veterinarians and owners were contacted for follow-up. Each institutional cohort was assessed separately, and the incidence density rate and median time to occurrence of OSA at the TPLO site and at other sites were calculated. Marginal Cox regression was used to calculate hazard ratios and 95% confidence intervals for potential risk factors for occurrence of OSA.
  
  
  RESULTS
  There were 472 CLINIC A (Colorado State University Veterinary Teaching Hospital) and 1992 CLINIC B (SAGE Centers for Veterinary Specialty and Emergency Care) TPLO cases with over one year of follow-up available. There were five and six dogs within the cohorts that developed OSA at the site of TPLO, and seven and 22 dogs that developed OSA at other anatomical sites, respectively. The incidence density rates of OSA at the TPLO site were 30.4 and 10.2 per 10,000 dog-years at risk, and other sites were 42.6 and 37.5 per 10,000 dog-years at risk. The median time to occurrence of OSA of TPLO site OSA was 4.6 and 4.4 years, which was longer than that of other site OSA of 2.9 and 3.4 years.
  
  
  CONCLUSIONS
  There is a low incidence of OSA following TPLO surgery. The longer time to occurrence for TPLO site OSA is similar to that for fracture-associated sarcoma, and could indicate a similar underlying pathophysiology rather than spontaneous OSA occurrence.
authors: A J
authors: AJ
authors: Sartor
authors: S D
authors: SD
authors: Ryan
authors: T
authors: T
authors: Sellmeyer
authors: S J
authors: SJ
authors: Withrow
authors: Dr. L. E. Selmic, Flint Animal Cancer Center, Department of Clinical Sciences, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, CO 80523, United States, E-mail: laura.selmic@gmail.com.
authors: L E
authors: LE
authors: Selmic
mesh_terms: D000818:Animals; D016118:Anterior Cruciate Ligament / Q000601:surgery*; D001859:Bone Neoplasms / Q000175:diagnosis / Q000209:etiology / Q000662:veterinary*; D004283:Dog Diseases / Q000209:etiology*; D004285:Dogs; D005260:Female; D008297:Male; D012516:Osteosarcoma / Q000209:etiology / Q000662:veterinary*; D010027:Osteotomy / Q000009:adverse effects / Q000662:veterinary*; D012189:Retrospective Studies; D013977:Tibia
keywords: Osteosarcoma; fracture site sarcoma; tibial plateau levelling osteotomy