Screw Fixation of the Posterior Malleolus Fragment in Ankle Fracture

Background: This study aimed to evaluate the outcomes of ankle fractures with posterior malleolus fragments (PMFs) involving <25% of the articular surface treated with or without screw fixation. Methods: Among patients with ankle fractures and PMFs who underwent surgery between March 2014 and February 2017, 62 with type 1 PMFs involving <25% of the articular surface were included. Of these 62 patients, 32 underwent screw fixation for PMFs and lateral and/or medial malleolar fracture fixation (group A) and 30 underwent internal fixation for malleolar fractures without screw fixation for PMFs (group B). Ankle joint alignment and fracture healing were measured using plain radiography and computed tomography (CT). Clinical outcomes were determined using the American Academy of Orthopaedic Surgeons Foot and Ankle Questionnaire, Short Form-36, and American Orthopaedic Foot & Ankle Society Scale. Results: Nonunion was not noted in either group. However, we detected union with a step-off of 2 mm or more in 2 cases from group B. With regard to ankle joint alignment, 1 case in group A and 3 cases in group B showed mild asymmetry of the medial and lateral clear spaces on CT at 12 months. Clinical outcomes at 6 and 12 months after surgery were better in group A than in group B. Conclusion: Screw fixation of PMFs was effective for fracture healing and maintaining ankle alignment. Additionally, it improved short-term clinical outcomes, which we believe was due to stabilization of ankle fractures with PMFs involving <25% of the articular surface. Level of Evidence: Level II, prospective comparative study.