Sequential Atraumatic Insufficiency Fractures of the Distal Fibula and Tibia: A Case Report

Insufficiency fractures result from physiological loading of bone with reduced mechanical resistance and may occur at uncommon sites in individuals with underlying skeletal fragility. Distal fibular insufficiency fractures are uncommon, and sequential involvement of the ipsilateral distal tibia appears particularly unusual. We report a 73-year-old postmenopausal woman who presented with atraumatic left ankle pain and swelling and was found to have a distal fibular fracture. Approximately two months later, while walking on level ground, she developed new lower-leg pain and swelling without trauma. Radiographs demonstrated interval healing of the fibular fracture together with a new nondisplaced distal tibial fracture. Subsequent computed tomography (CT) demonstrated a diffuse osteopenic appearance of the visualized bones, progressive healing of both fractures, and no focal or infiltrative osseous lesion. Both fractures healed progressively with non-operative management, and subsequent bone-health assessment demonstrated osteopenia. A focused narrative review of the literature identified isolated, bilateral, and recurrent distal fibular stress fractures, as well as concurrent distal tibial and fibular fractures, but no directly comparable distal fibula-to-ipsilateral-distal-tibia sequence. This case highlights the potential importance of an initial insufficiency fracture as a sentinel fragility event. New or changing symptoms after such an event should prompt consideration of an additional insufficiency fracture, together with assessment of systemic skeletal health and potentially contributory biomechanical factors, including altered loading during fracture recovery.