Risk factors for long bone fracture non-union: a stratification approach based on the level of the existing scientific evidence.

Non-union continues to be the most devastating complication after fracture fixation. Its treatment can be prolonged and often unpredictable. The burden to the patient, surgeon and health care system can be immense. Strategies to prevent it and or identify early its development are desirable in order to improve the clinical course of the affected patients and their outcomes. We undertook a systematic review of the literature in order to identify the most common and important risk factors based on the hierarchy of level of evidence. Accordingly, a stratification scale was formed which highlighted 10 risk factors including; an open method of fracture reduction, open fracture, presence of post-surgical fracture gap, smoking, infection, wedge or comminuted types of fracture, high degree of initial fracture displacement, lack of adequate mechanical stability provided by the implant used, fracture location in the poor zone of vascularity of the affected bone, and the presence of the fracture in the tibia. Clinicians should take in to account these findings when managing patients with long bone fractures, particularly the femur and tibia in order to minimise the risk of non-union.