Osteoporosis is a disease of the skeletal system that causes the bones to become weak and susceptible to fracture. The most common sites for these types of fractures are in the hip, spine and wrist, though they may occur anywhere. There has been no single cause identified in osteoporosis however it is characterized by a loss of bone density. There is no cure for osteoporosis but there are several treatment methods available and it is largely preventable in most people.