Two cases of trapping of the posterior tibial tendon, in one of which there was associated trapping of the posterior tibial nerve, and two cases with interposition of a reflected portion of the deltoid ligament within the medial aspect of the joint space, are presented as complications of severe fracture-dislocation of the ankle joint, requiring open reduction. Failure to achieve anatomical reduction in fractures about the ankle is probably the largest cause of poor end results. It is suggested that any patient with fracture-dislocation of the ankle1 in which there is severe medial ligamentous injury and disruption of the mortise, which cannot be reduced by initial closed manipulation, be considered a candidate for early open surgical reduction. True anteroposterior roentgenograms of the ankle joint are necessary for any critical evaluation of mortise alignment.