 Vertebral fractures and hip has undoubtedly the greatest impact on walking ability of the elderly, and great attention is given to these two types of fracture. Consequently, there are currently insufficient data on the epidemiology and evolution of other fragility fractures, also known as non-vertebral non-hip fracture NVNH. Among these, distal radius and proximal humerus fractures are the most frequent. There is a type of fracture, however, that is simply ignored by the medical community: the knee insufficiency fracture. The fact that no literature study even hypothesize that this type of fracture may be a fragility fracture may be because, until a few years ago, it was believed that this entity was a osteonecrosis of the knee. The knee insufficiency fracture usually occurs in older individuals and those with knee osteoarthritis. This study therefore aims to evaluate whether a relation between the knee insufficiency fracture and osteoporosis. Moreover, it is expected to find out if this fracture may be defined as a fragility fracture, electing the individuals affected by it to a prophylaxis for the occurrence of new osteoporotic fracture. 