Differential Diagnosis of Scapular Winging: A Case Report

BACKGROUND: Diagnosing the cause of scapular winging can be difficult, often requiring a systematic clinical examination and electrodiagnostic testing. Long thoracic nerve (LTN) palsy is often suspected and must be ruled out. CASE PRESENTATION: A 26-year-old male sustained a posterior labral tear and subsequent posterior labral repair. He reinjured his shoulder and examination revealed significant scapular winging and signs of posterior instability. Electrodiagnostic testing impression was positive for a LTN palsy. He was to undergo a pectoral muscle transfer, but a thorough scapular muscle examination revealed full serratus activity. Electromyography evaluation was performed without and with cueing, demonstrating minimal and normal serratus activity, respectively. OUTCOME AND FOLLOW-UP: The patient gained serratus anterior control and was spared from unnecessary surgery. DISCUSSION: Despite findings on electrodiagnostic testing suggesting LTN, a thorough examination was able to elucidate that this patient’s scapular winging was due to serratus anterior inhibition. A specific examination algorithm can improve diagnostic accuracy.