Atypical Triplane Ankle Fracture - Antero-Medial Epiphyseal Separation and the Unfused Growth Plate: A Case Report.

Introduction: Triplane fractures represent a complex injury that occur at the distal tibia in the pediatric population and follow a characteristic pattern in keeping with the progressive closure of the physis typically from age 12 to 17. We present a case of a triplane variant where the medial growth plate was unfused leading to an additional mobile antero-medial fracture fragment. The rarity of our case makes this a very interesting one. Case Report: A 16-year-old Caucasian boy presented to the emergency department after slipping on wet grass and injuring his left ankle. He was unable to weight bear. He sustained an isolated and closed injury. He had no significant medical comorbidities and was otherwise a fit and active teenager. Following initial investigations, a triplane ankle fracture was diagnosed, and he was placed into a short leg cast and referred directly to the orthopedic trauma team for admission. Conclusion: Atypical triplane variants are rare. The presence of an additional anteromedial epiphyseal fragment separated from the metaphysis and remaining portion of the epiphysis is even rarer. We present the surgical management of such a case in our unit, with a good patient outcome.