Excerpts from Books and Wikipedia
"On June 14, Jackson served as a second in a duel on behalf of his junior officer William Carroll against Jesse Benton, the brother of Thomas. In September, Jackson and his top cavalry officer, Brigadier General John Coffee, were involved in a street brawl with the Benton brothers. Jackson was severely wounded by Jesse with a gunshot to the shoulder." [Wikipedia]
"When he began the campaign he was still recovering from the gunfight with the Bentons. For months he could barely move his arm because of the shattered bone. Then pieces of the bone 'came out of my arm' (and he sent them to Rachel as a souvenir)." [Andrew Jackson 1, p. 223-4]