This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Shoulder and arm injuries, Subject name: Orthopaedics
[{'content': 'Posteroinferior instability of glenohumeral joint is tested by \nSelect and explain. \nA. Jerk test, B. Crank test, C. Fulcrum test, D. Sulcus test', 'role': 'user'}, {'content': 'Answer: A \nExplanation: This test is used to detect posteroinferior instability of glenohumeral joint. While stabilizing the patient&;s scapula with one hand and holding the affected arm at 90 degrees abduction and internal rotation,the examiner grasps the elbow and axially loads the humerus in a proximal direction.The arm is moved horizontally across the body. A POSITIVE result is in indicated by a sudden clunck as the humeral head slidesoff the back of the glenoid.When the arm is returned to the original position,a second jerk may be observed,that of the humeral head returning to the glenoid. Ref: Maheshwari and Mhaskar 9th ed pg 95.', 'role': 'assistant'}]