Osteoporosis (OP) is a bone disease which affects a number of post‐menopausal females and puts many at risk for fractures. A large number of patients are taking bisphosphonates (BPs) to treat their OP and a rare complication is the development of atypical femoral fractures (AFF). No real explanations for the mechanisms underlying the basis for development of where AFF develop while on BPs has emerged. The present hypothesis will discuss the possibility that part of the risk for an AFF (...) is a secondary effect of BPs on a subset of vascular cells in a genetically at‐risk population, leading to localized deregulation of the endothelial cell (EC)‐bone cell‐matrix units in nutrient channels/canals of the femur and increased risk for AFF. This concept of targeting ECs is consistent with location of AFF in the femur, the bilateral risk for occurrence of AFF, and the requirement for long term exposure to the drugs. (shrink)

Bisphosphonates are a class of drugs which have shown good efficacy in the treatment of post‐menopausal osteoporosis, as well as a good safety profile. However, side‐effects such as risk for atypical femoral fractures (AFF) have appeared, leading to a decline in use of the drugs by many patients who would benefit from the treatment. While patient characteristics have contributed to improved understanding of risk factors, the mechanisms involved that explain AFF risk have not appeared. Recently, the possibility that the (...) mechanism(s) involved drug‐induced modification of cells of the nutrient canals of the femur and subsequent compromise in the bone matrix has been published. The present Hypothesis article builds on the concept presented earlier and expands into biomechanical considerations. An analogy of the mechanisms involved to a real‐life scenario is also presented. While this analogy has limitations, consideration of the biomechanical implications of progressive alterations to defects presented by compromised nutrient canal‐bone matrix also presents potential relationships with AFF risk. (shrink)