Fractured femur. Coloured X-ray of a broken femur repaired with a dynamic hip screw (blue). The bone has been surgically immobilised by the insertion of a long metal pin fixed to the bone with metal screws. The fracture of the femur is very common in elderly people, especially in women suffering from osteoporosis (thinning of the bone), and usually affects the neck of the femur. Dynamic hip screws are used to increase the stability of the joint and to allow early mobilization after a fracture.