18-year-old male status post trauma assess for thumb MCP ulnar collateral ligament injury. Pain and swelling. The ulnar collateral ligament of the metacarpophalangeal joint is abnormally thickened and detached from the base of the proximal phalanx indicating a tear. The ulnar margin of the base of the proximal phalanx appears disrupted with edema in the underlying bone likely representing a fracture. There is a 2 mm focus of fat signal intensity within the soft tissues adjacent to the suspected fracture which may represent a mildly displaced avulsion fracture fragment. We see no specific findings to suggest a Stener lesion. The accessory ulnar collateral ligament, although thickened, may be intact. The radial collateral ligament is intact. The interphalangeal joint and basilar joint of the thumb are unremarkable. The flexor and extensor tendons are intact.
Tear of the ulnar collateral ligament with findings suggestive of a small avulsion fracture off the base of the proximal phalanx.