Gamekeepers thumb

47 year old woman who presents with thumb pain and painful abduction. A series of hand radiographs coned and centered on the thumb were acquired. As indicated by the red arrow, there is a fracture of the ulnar aspect of the base of the thumb metacarpal. This fracture is secondary to tear and avulsion of the ulnar collateral ligament. This fracture is referred to as a Gamekeepers thumb as it was initially described in gamekeepers who would break their thumb while breaking the necks of rabbits in the field. It now is seen most frequently following a ski accident. The role of MRI is to determine whether the torn ends of the ulnar collateral ligament are interposed between the adductor pollicis aponeurosis. If this finding is present, the ligament must be repared surgically.