Osteoporosis is a chronic and progressive disease which makes the bones weaker and liable to break more easily. It is known as a "silent disease", as the loss of bone mass occurs without presenting any symptoms or ailments. Patients are therefore unlikely to discover that they have this disease until they break a bone due to a fall or pulled muscle. This condition presents in elderly people in particular, the majority of whom are women. It is the main cause of prolonged hospital admissions in women over 45 years of age.