Irreducible Ankle Fracture from an Interposed Chaput Fragment: A Case Report.

Case: A 23-year-old active-duty military service member sustained an unusual irreducible fracture-dislocation of the ankle joint. Preoperative computed tomography showed an anterolateral tibial (Chaput) fragment entrapped within the distal syndesmosis, preventing adequate reduction. An open reduction of the fragment was performed in the operating room, which allowed near-anatomic reduction and internal fixation of the tibiotalar joint. At the 21-month follow-up visit, the patient remained on active duty in the Navy without limitations.

Conclusion: To our knowledge, this rare injury pattern, an interposed Chaput fragment preventing closed reduction of the syndesmosis in a skeletally mature patient, has not previously been described in the literature. An open reduction and internal fixation of the Chaput fragment allowed near-anatomic reduction of the tibiotalar joint.