Extraperiosteal plating of pronation-abduction ankle fractures.

BACKGROUND:
Pronation-abduction ankle fractures frequently are associated with substantial lateral comminution and have been reported to be associated with the highest rates of nonunion among indirect ankle fractures. The purpose of the present study was to report the technique for and outcomes of extraperiosteal plating in a series of patients with pronation-abduction ankle fractures.

METHODS:
Thirty-one consecutive patients with an unstable comminuted pronation-abduction ankle fracture were managed with extraperiosteal plating of the fibular fracture. The average age of the patients was forty-four years. There were nineteen bimalleolar and twelve lateral malleolar fractures with an associated deltoid ligament injury. No attempt to reduce the comminuted fragments was made as this area was spanned by the plate. The patients were evaluated functionally (with use of the American Orthopaedic Foot and Ankle Society score), radiographically, and clinically (with range-of-motion testing).

RESULTS:
Immediate postoperative and final follow-up radiographs showed that all patients had a well-aligned ankle mortise on the fractured side as compared with the normal side on the basis of standardized measurements. All fractures healed without displacement. At a minimum of two years after the injury, the average American Orthopaedic Foot and Ankle Society score (available for twenty-one patients) was 82. The range of motion averaged 13 degrees of dorsiflexion and 31 degrees of plantar flexion, with one patient not achieving dorsiflexion to neutral. There were no deep infections, and one patient had an area of superficial skin breakdown that healed without operative intervention.

CONCLUSIONS:
Extraperiosteal plating of pronation-abduction ankle fractures is an effective method of stabilization that leads to predictable union of the fibular fracture. The results of this procedure are at least as good as those of other techniques of open reduction and internal fixation of the ankle, although specific results for pronation-abduction injuries have not been previously reported, to our knowledge.