Fractured neck of thigh bone. Coloured computed tomography (CT) scan showing a fracture (centre left) through the neck of the thigh bone (femur) due to the bone disease osteoporosis. This scan shows a slice through the body: at centre right is the ball-and-socket joint of the hip; the yellow bone on the right is the pelvis. Osteoporosis is the loss of protein tissue inside bone, causing it to become brittle and easily fractured. The condition is a natural part of aging and leads on average to a one-third loss of bone density by age 70. Post-menopausal women are the most severely affected due to loss of the hormone oestrogen, which helps maintain bone mass.