Stress-Related Acromion Base Fracture after Clavicular Hook Plate Fixation: A Case Report.

Introduction: Clavicular hook plate fixation is widely used for the surgical management of high-grade acromioclavicular (AC) joint injuries and generally provides reliable clinical outcomes. Nevertheless, implant-related complications involving the acromion have been reported. Stress-related fractures at the base of the acromion following hook plate fixation are extremely rare and remain poorly described in the literature. Case Report: A 48-year-old woman sustained a high-grade AC joint injury and underwent open reduction and internal fixation with a clavicular hook plate. Two months after surgery, she presented with acute shoulder pain and functional limitation following minor trauma. Imaging studies revealed failure of the hook plate construct associated with a displaced fracture at the base of the acromion, resulting in compromise of the subacromial space. The patient was treated surgically with implant removal, fixation of the acromial fracture using a tension-band technique, and restoration of AC and coracoclavicular stability. Post-operative imaging demonstrated satisfactory reduction, and the patient achieved functional recovery during follow-up. Conclusion: This case illustrates a rare stress-related fracture of the acromion base following clavicular hook plate fixation, with a fracture pattern distinct from the typical hook plate cut-out mechanism. Awareness of this potential complication and individualized surgical management based on fracture morphology and shoulder girdle stability are essential for achieving favorable outcomes.