How do you tell apart a pcl strain and a pcl tear (by symptoms)?

It could be difficult to tell the difference between PCL strain (sprain) and mild (stage1,2) PCL tear. Because PCL is the strongest ligament so a PCL tear is usually associated with other ligament injury. So by physical exam, doctor suspects a PCL injury and if there is other evidence of lateral ligament or ACL injury, PCL tear is more likely than just a strain.