25 rare isolated fractures of the dorsal tibial margin out of 2500 ankle-lesions have been analysed. The mechanism consists of extensive plantar flexion followed by axial impact of the astragalus against the posterolateral part of the mortise. The tense condition of the syndesmotic apparatus forces it to pull off the dorsal insertion wedge on the distal tibia with an articular component of different size. Small and undislocated fragments are prevalent. Torn anterior tibiofibular ligament and parts of the interosseous membrane are typical concomitants of this lesion. Neither fibular nor medial structures of the ankle joint have been harmed. Orthotopic bony union of the tibial margin and ligament healing is safe within three weeks of non-weight-bearing immobilisation followed by the same period of walking cast. Large dislocated fragments require operation. Most patients have excellent or good results as our follow-up study confirms.
