[Rupture of the ulnar, collateral ligament of the metacarpophalangeal joint of the thumb, so-called 'wobbly thumb'].

A stable metacarpophalangeal joint of the thumb is indispensable for a normal grip function of the hand. The joint is stabilized by collateral ligaments. A rupture of the ulnar, collateral ligament is often caused by a sports trauma, as indicated by the denominations "skiërs duim", "goalkeeper's thumb" and "baseball thumb". Many surgeons are not familiar with the phenomenon of an insufficient collateral ligament, also called "wackeldaum". In the period 1981-1985 a consecutive series of 35 patients with a ruptured ulnar collateral ligament was operated in the De Wever hospital Heerlen (Netherlands). On the basis of our own patients, attention is given to the diagnosis, therapy and results of the operative treatment of these lesions.