Ten RCTs published between 2000 and 2013 support treating distal radius buckle fractures and other low-risk distal radius fractures with a removable splint and with no orthopaedic follow-up. Application of this evidence has been shown to be variable and suboptimal resulting in unnecessary costs to a strained healthcare system. The Canadian evidence on this topic has been generated by subspecialist physicians working in paediatric hospitals. It is unclear what factors affect the dissemination of this information. We investigated the association of hospital type and physician type with the application of best-evidence treatment for low-risk distal radius fractures in children with the goal of improving our understanding of evidence diffusion in Ontario for this common injury. We performed a retrospective population-based cohort study using linked health care administrative data. We identified all children aged 2–14 treated in Ontario emergency departments from 2003–2015 with distal radius fractures with no reduction and no operation within a six week period. We excluded refractures and children with comorbidities. We evaluated the followup received – orthopaedic, general practitioner, or none. We examined the data for trends over time. Multivariable log binomial regression was used to quantify associations between hospital and physician type and best-evidence treatment. We adjusted for patient-related variables including age, sex, rural or urban location, and socioeconomic status. 70,801 fractures were analyzed. Best-evidence treatment was more likely to occur in a small (RR 1.86, 95%CI 1.72–2.01), paediatric (RR 1.16, 95%CI 1.07–1.26), or community (RR 1.13, 95%CI 1.06–1.20) hospital compared with treatment in a teaching hospital. Best-evidence treatment was more likely if initial management was by a paediatrician with additional emergency medicine training (RR 1.73, 95%CI 1.56–1.92) or paediatrician (RR 1.22, 95%CI 1.11–1.34). Paediatric and teaching hospitals have improved their use of best-evidence over time while other hospital types have stagnated or deteriorated. Paediatricians, paediatricians with additional emergency medicine training, and emergency medicine residency trained physicians have improved their use of best-evidence over time, while other physician types have stagnated or deteriorated. Overall, only 20% of patients received best-evidence treatment and 70% had orthopaedic follow-up. Significant over-utilization of resources for low-risk distal radius fractures continues decades after the first randomized trials showed it to be unnecessary. Physician type and hospital rurality are most strongly associated with best-evidence treatment. Physician types involved in generating, presenting, and publishing best-evidence for this fracture type are successfully implementing it, while others have failed to change their practices. Rural hospitals are excellent resource stewards by necessity, but are deteriorating over time. Our results strongly indicate the need for targeted implementation strategies to explicitly apply clinical evidence in clinical practice Canada-wide, with the goal of providing more cost-effective care for common children's fractures