Simultaneous avulsion fracture of the insertion of the ulnar and radial collateral ligaments of the metacarpophalangeal joint of the thumb

We present a case of simultaneous avulsion fracture of the insertion on the volar base of theproximal phalanx of the ulnar and radial collateral ligaments of the metacarpophalangeal joint of the thumb. To our knowledge this combination has never been published before. The mechanism of this injury is not clearly understood.