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What is Light-bulb sign in X-ray shoulder is seen in: and explain in detail?
Ans-CKef: Apleys System of Orthopaedics and Fractures, 9th editionExplanation:Eight-bulb appearance - Seen due to internal rotation of the humeral head in posterior dislocation of the shoulder.Anterior dislocation of shoulder occurs from the excessive external rotation of the shoulder (especially in abduction).Risk factors of posterior shoulder dislocation of the shoulder occur from:o Excessive internal rotationo Following seizure episodeo Following electrocutiono In both seizure and electrocution, excessive contraction of the stronger muscles of the upper back causes pull of the humeral head backward causing dislocation.* Normal appearance of the shoulder in X-ray.Eight-bulb appearance of the humeral head in X-ray due to internal rotation of the humeral head in posterior dislocation.NOTE associated with anterior shoulder dislocation - Fracture of the greater tuberosity. associated with posterior shoulder dislocation - Fracture of the lesser tuberosity.