Osteosynthese von Frakturen der anterolateralen distalen Tibia: der vordere Knöchel

Objective: The anterior tibial rim with the anterolateral tibial tubercle provides attachment to the anterior tibiofibular syndesmosis. It may be considered an anterior or “fourth” malleolus. Fixation of a displaced anterior tibial fragment in the treatment of malleolar fractures aims at providing a bone-to-bone fixation of the anterior tibiofibular ligament and restoring the integrity of the tibial incisura. Indications: Displaced intra-articular fragments of the anterior tibia; fractures involving the tibial incisura; fractures with intercalary fragments; impaction of the anterior tibial plafond; syndesmotic avulsions producing instability or preventing reduction of the distal fibula into the tibial incisura. Contraindications: Critical local soft tissues preventing an anterolateral approach; missing consent to surgery by the patient; overall critical general condition preventing surgery to the extremities. Surgical technique: Anterolateral approach over the tibial tubercle. Identification and mobilization of the anterior tibial fragment without dissecting the anterior syndesmosis. Reduction of the anterior tibial fragment with a pointed reduction clamp. Fixation of extra-articular avulsion fractures (type 1) with suture anchor. Screw fixation of larger fragments involving the joint surface and incisura (type 2). Disimpaction, realignment of the joint surface, bone grafting as needed and plate fixation of impaction fractures of the anterolateral tibial plafond (type 3). Postoperative management: Mobilization with partial weight bearing (15–20 kg) in a special boot (ankle foot orthosis) or cast for 6–8 weeks depending on the overall malleolar fracture pattern, bone quality and patient compliance. Results: Few studies report the results of anterior tibial fractures in adults. Failure to fix displaced fragments frequently leads to nonunions. Overlooked Chaput fractures have been reported to result in malpositioning of the distal fibula in the tibial incisura leading to incongruity of the ankle mortise requiring revision surgery. Secondary avascular necrosis of the anterolateral tibial plafond may develop after joint impaction.