This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Orthopaedics
[{'content': 'A patient met with Road Traffic Accident with injury to the left knee. Dial test was positive. What could be the cause ? \nSelect and explain. \nA. Medial Collateral Ligament Injury, B. Posterolateral Corner Injury, C. Lateral Meniscus Tear, D. Medial Meniscal Injury', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Dial test or Tibial External Rotation Test: \n\nThis is the test for posterolateral instability.\nThe tibia is externally rotated on femur first at 30° flexion and then at 90° flexion. Comparison is made with the normal side.\nAn increase in external rotation of greater than 10°\n\n\nAt 30° of flexion but not at 90° indicates an isolated posterolateral corner injury.\nAt both 30° and 90° of flexion indicates injury of both posterior cruciate ligament and posterolateral corner.\n\n\nThe posterolateral corner (PLC) is a complex that includes the lateral collateral ligament (LCL), popliteus tendon, fabellofibular ligament, arcuate ligament, popliteofibular ligament, and the short lateral ligament.', 'role': 'assistant'}]