Radiographic Results of Unicortical Medial Malleolar Fracture Fixation

Background: Medial malleolar fractures commonly occur as part of rotational ankle fractures, which often require surgery. Different fixation techniques exist, including unicortical or bicortical lag-screw fixation. Bicortical screws that engage the lateral distal tibia have been noted to be biomechanically superior to unicortical ones with a lower failure rate. The authors of this study have used unicortical screws routinely. This study was initiated to investigate the clinical results of a large series of patients with unicortical medial malleolar fixation. Methods: Patients who underwent unicortical medial malleolar fracture fixation between 2011 and 2017 were reviewed. In total, 461 ankle fractures were identified with a mean follow-up of 11.4 months (range, 3-57), of which 211 had a medial malleolar fracture. Eight patients were excluded as they did not follow up with the treating surgeons after surgery, leaving 203 patients for evaluation. The primary outcome was radiographic union. Any loss of reduction, complication, or subsequent surgery was recorded. Malunion was defined as greater than 2 mm displacement. Results: There were 2 asymptomatic nonunions (1.0%), 1 delayed union that healed using an external bone growth stimulator (0.5%), and 2 malunions of the medial malleolus (1.0%) with 1 asymptomatic. The other patient developed posttraumatic osteoarthritis but has not yet required further surgery. None of these 5 patients required revision medial malleolar surgery. Ultimately, the union rate using unicortical medial malleolar fixation was 99.0% (201/203). Conclusion: Unicortical fixation of medial malleolar fractures resulted in consistently good healing. Even though biomechanical studies have shown that bicortical screws provide stronger fixation, our clinical results indicate that the need for this stronger fixation may be questionable.