Osteoporosis is a disease characterized by low bone mass and deterioration of bone tissue. This leads to increased bone fragility and risk of fracture (broken bones), particularly of the hip, spine, wrist and shoulder. Osteoporosis is often known as “the silent thief” because bone loss occurs without symptoms. Osteoporosis is sometimes confused with osteoarthritis, because the names are similar. Osteoporosis is a bone disease; osteoarthritis is a disease of the joints and surrounding tissue.