Osteoporosis. Coloured Xray of the hip of a 43 year old woman showing reduced bone density (yellow patchy area) in the head of the thigh bone (femur, centre right). This is known as brittle bone disease or osteoporosis. In osteoporosis the bones lose mass, becoming weak and brittle, and the head of the femur is a common place for an osteoporotic fracture. Osteoporosis occurs most frequently in women after the menopause, as the ovaries cease production of the oestrogen hormones that help maintain bone mass. Hormone replacement therapy (HRT) may help to reduce bone loss, while regular exercises keep joints strong and supple.