Png MA, et al. - The radiographs of 76 consecutive patients (92 femurs) with 161 femoral stress fractures (FSF) were reviewed by the experts in order to understand the natural incomplete atypical femoral fractures in patients following a prolonged and variable course of bisphosphonate therapy. There was a natural progression from normal bone, to focal cortical thickening, to the dreaded black line and ultimately to a displaced fracture in FSF. Most lesions continued, persisting to be static or growing, particularly if a dreaded black line was there and bisphosphonates were continued. When bisphosphonates were stopped, regression was uncommon and more prevalent. Irrespective of stopping bisphosphonates, there continued to be a 10.9% risk of progression to displaced fracture.