<prompt> A patient met with Road Traffic Accident with injury to the left knee. Dial test was positive. What could be the cause ?Medial Collateral Ligament InjuryPosterolateral Corner InjuryLateral Meniscus TearMedial Meniscal Injury  <response>: Dial test or Tibial External Rotation Test: This is the test for posterolateral instability.The tibia is externally rotated on femur first at 30 flexion and then at 90 flexion. Comparison is made with the normal side.An increase in external rotation of greater than 10At 30 of flexion but not at 90 indicates an isolated posterolateral corner injury.At both 30 and 90 of flexion indicates injury of both posterior cruciate ligament and posterolateral corner.The 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. 