Broken hip. Coloured X-ray of the pelvic region of an elderly woman with a fractured femur (far left, red) caused by a fall. The round femur head articulates with the pelvis at the hip socket (centre left). The femur (thigh bone) is fractured at the top of the shaft of bone. The risk of a break was increased by osteoporosis (brittle bone disease), which causes a loss in bone density. Bones become thinner and more brittle, and so more likely to break under trauma. Osteoporosis is most common in women after the menopause because their ovaries no longer produce the oestrogen hormones that help to maintain bone mass.