Urban legend. He appeared to have an injured leg when he visited Hawaii in 1970, but he looks perfectly ok standing there surrounded by some of his old classmates, union buddies and Stanley Armour Dunham, when he departed:
Doesn't answer the question as to who that girl is that's snuggled into his side, so close they had to load the image up with fake lei to try and hide it...he was only in Hawaii for a month. Quite the lady-killer.