Osteoporosis. Artwork of a hip joint where the neck of the femur (thigh bone) has fractured due to osteoporosis. Osteoporosis is a condition where the loss of calcium causes bones to become brittle and prone to fracture. It is most common in women after the menopause because they no longer produce the hormone oestrogen that helps in keeping bones healthy. Broken hips are a common injury sustained during falls by elderly women, and often require a hip replacement operation. The hip joint is where the head of the femur bone fits into its socket in the pelvis. The socket is lined with a lubricating tissue called cartilage (pink).