The pilot reported that he had a normal stabilized descent on approach and flared about 50 feet above the runway. He indicated he made a three-point touchdown. He said that during the roll the airplane tracked to the right and he applied left rudder. He stated that he heard a "bang" and the airplane moved abruptly and uncontrollably. The left wing and horizontal stabilizer sustained substantial damage when they contacted the runway. Examination of the airplane revealed that the left wheel and axle separated from its main landing gear. Two of the four bolts that attach the axle to the gear exhibited a separation consistent with fatigue.