Unobvious diagnosis: subcoracoid impingement. Current knowledge about this condition.

Subcoracoid impingement (SCI) is one of the possible causes in anterior shoulder pain that can be misdiagnosed or missed. It results from a conflict between the coracoid process and the lesser tuberosity of the humeral head. The collision mainly affects the subscapularis tendon that is at risk of degeneration and tearing. The symptoms arise by positioning the shoulder in flexion, adduction and internal rotation, dynamically decreasing the coracohumeral distance, the most important diagnostic parameter in the SCI. The impingement has been associated with shoulder overuse that may occur in specific sport activities, such as freestyle swimming and overhead throwing. Ultrasound scan, MRI and arthroscopy may help in the identification of pathology. Although not suitable for soft tissue imaging, X-ray may be helpful in detecting bony factors contributing to SCI. The first and main line of treatment is usually conservative, but when it fails, bursectomy followed by mild coracoplasty is a safe and effective method. Patients may also need a repair of the subscapularis tears.