A patient met with Road Traffic Accident with injury to the left knee. Dial test was positive. What could be the cause ?

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 10° At 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.