Ans. b. Posterior dislocation Posterior Dislocation of Shoulder is caused by indirect force producing marked internal rotation and adduction, most commonly during a fit, convulsions or an electric shock Posterior Dislocation of Shoulder Mechanism of injury: Indirect force producing marked internal rotation and adductionQ most commonly during a fit, convulsions or an electric shockQ Clinical Presentation: Diagnosis is frequently misseddeg, patient may have normal contour of shoulder The classical clinical feature is arm is held in medial rotation and is locked in that positiondeg and the examiner cannot externally rotate it. Diagnosis: X-Ray: Due to medial rotation, head looks abnormal (electric bulb sign)deg and it stands away somewhat from glenoid fossa (empty glenoid sign)Q