Avulsion Injury of the Serratus Anterior

OBJECTIVE: We report the first documented case of avulsion of the serratus anterior muscle. A young man had difficulty in abducting his arm the day after using a rowing ergometer. Examination showed a firm mass on his lateral thoracic wall. This became firm with protraction of the scapula. Avulsion was confirmed by magnetic resonance imaging (MRI) scanning. Rest and modified activities resulted in resolution of symptoms. DISCUSSION: This case highlights the role of serratus anterior in the rowing action and supports its implication in stress fractures of the ribs. An imbalance between rhomboids and serratus anterior is the proposed cause of such avulsion injury. CONCLUSIONS: Difficulty with abducting the arm may result from pathology outside the glenohumeral joint. Athletes should be advised to use care when starting any new exercise.