Untreated radial collateral ligament rupture of the thumb metacarpophalangeal joint may lead to an impairment of thumb function. The treatment is basically similar to ulnar ligament trauma management. Due to the rarity of this lesion, consistent guidelines for therapy have not yet been described. In contrast to fresh injuries a re-fixation of the disrupted ligament usually is not possible when chronic instability has already occurred. Following functional-anatomic considerations a dynamic joint stabilization method has been developed by transposition and thus reestablishing the functional direction of the abductor pollicis brevis muscle. Thus the physiological radial ligament vector is replaced and a functional ligament replacement is achieved through a technically simple procedure.