Floating fibula with associated multiligament knee injury: a case report and literature review

Background A "floating fibula" is a rare and severe injury pattern characterized by complete disruption of both proximal and distal tibiofibular attachments. Its association with a multiligamentous knee injury (MLKI) has not been previously documented. Methods and results We report the case of a 27-year-old male who sustained high-energy trauma in a motorcycle accident, resulting in a complex MLKI with anterior cruciate ligament (ACL), posterior cruciate ligament (PCL), medial collateral ligament (MCL), and posterolateral corner (PLC) injuries, associated with complete disruption of the proximal and distal tibiofibular joints. Initial management included external fixation and soft tissue stabilization, followed by definitive one-stage surgery consisting of arthroscopic ACL and PCL reconstruction, PLC reconstruction using a tibialis anterior allograft, proximal MCL repair using an all-suture anchor fixation, and open reduction and fixation of the distal tibiofibular syndesmosis. The proximal tibiofibular joint was stabilized through a soft tissue-based reconstruction integrated with the PLC graft. Postoperative imaging confirmed anatomic alignment, and at 12 months, the patient demonstrated a stable knee during clinical testing with 0–115 degrees flexion and preserved ankle dorsiflexion. Conclusion This report highlights the diagnostic and surgical challenges of managing concurrent MLKI and floating fibula injuries. Restoration of both proximal and distal tibiofibular joint stability is essential to maintain physiological fibular biomechanics and achieve optimal knee and ankle function. Early recognition and a tailored, anatomically based fixation strategy are critical for restoring lower limb stability and function.