Yang TC, Tzeng YH, Wang CS, et al. - This research was sought to distinguished risk factors for complications following this procedure. Researchers assessed the ratio of the fracture site diameter to the diameter of the femoral intramedullary canal of the isthmus (FI ratio) as a novel parameter to predict complication. Between January 2008 and December 2018, researchers retrospectively examined individuals who had undergone antegrade IM nailing for infra-isthmus femoral shaft fracture and had a minimum of 12 months of follow-up. They further computed the sensitivity and specificity of the FI ratio as a predictor of complication. The study included a total of 65 patients with a mean age of 47.1 years. The results demonstrate that at the fracture site, a wider intramedullary diameter was associated with a higher complication rate following antegrade IM nailing in distal infra-isthmal femoral fractures. After antegrade IM nailing, the FI ratio could be a reliable predictor of complication for such fracture, and alternative strategies should be considered for patients with a higher FI ratio (≥ 2).