[Operative treatment of pronation fracture--dislocations of the ankle]

Early reduction of the dislocation and anatomic reconstruction of axial alignment, ankle mortise and articular congruity with special focus on syndesmotic stability.

Fracture-dislocations resulting from pronation injuries to the ankle with a highly incongruent and unstable mortise and either considerable internal pressure on the soft tissues by the displaced fragments or open soft tissue damage.

General contraindications to surgery: closed reduction and cast immobilization or external fixation.

Early preoperative closed reduction of complete dislocations is achieved through longitudinal traction and movements contrary to the original fracture mechanism. A cast or joint-spanning external fixator is applied temporarily. Ideally, definite anatomic reduction of the posterior tibial fragment, the distal fibula and medial malleolus and stable internal fixation is achieved within the first hours after the injury. Congruity of the ankle mortise and syndesmotic stability is controlled intraoperatively and a syndesmotic screw is inserted if necessary. In these cases, the correct positioning of the distal fibula within the tibial incisura is verified with three-dimensional fluoroscopy or postoperative computed tomography scanning.

Early range of motion exercises of the ankle and subtalar joints are initiated the second postoperative day or after soft tissue consolidation and removal of the external fixation. Patients are mobilized with partial weight bearing (20 kg) in a cast or special boot for 6 weeks postoperatively. The syndesmotic screw is then removed in most cases and weight-bearing is rapidly increased.

The presence of a dislocation at the time of injury represents a negative prognostic factor in malleolar fractures. Higher rates of posttraumatic arthritis are also observed with trimalleolar fracures, especially fractures of the posterior tibial rim, cartilage damage, and syndesmotic disruption. Irrespective of the fracture classsification, good to excellent results can be obtained in 75-89% of cases with anatomic reconstruction of the ankle mortise and the articular surfaces. Proper reduction of the distal fibula into the tibial incisura is of utmost importance in cases of frank syndesmotic diastasis.