RESUMO
Thoracic outlet syndrome is a relatively common disease. However, costoclavicular syndrome as a condition secondary to nonunion of a displaced fracture of the clavicle is very rare. Most clavicular fractures in adults are united with no or minimal persistent symptoms. Also, symptomatic nonunion of a displaced fracture of the clavicle is rare. A 55-year-old male initially presented with persistent forearm pain after slip-down was initially diagnosed with simple muscle strain. However, he was given a delayed diagnosis of costoclavicular syndrome, caused by compression of the subclavian artery due to trauma in the fibrotic nonunion of the right clavicle without apparent symptoms. We obtained satisfactory results by surgical treatment. Here we report this case with a review of the literature.