Serratus anterior disruption: a complication of rheumatoid arthritis

Pathology influencing the serratus anterior muscle contributes to classical medial winging of the scapula. Serratus anterior weakness or injury interferes with regular shoulder movement as this muscle stabilizes the medial border of the scapula against the thorax and rotates the scapula upward and laterally with arm elevation. Traumatic injury to the serratus anterior muscle without electrodiagnostic evidence of neurogenic involvement has only been reported once previously. We report an unusual case of disruption of the serratus anterior as a complication of rheumatoid arthritis. Involvement of the long thoracic nerve was ruled out by electromyography and nerve conduction studies. The injury occurred during routine activities of daily living and was complicated by a recurring subscapular hematoma. Contributing factors of shoulder joint contractures and coagulation abnormalities were associated with the course and treatment of rheumatoid arthritis. Initial treatment was by joint immobilization and reversal of coagulation abnormalities. Later treatment was directed toward joint protection and gradually increasing range of motion exercises.