We rate sprained knees in three different grades, each increasing in severity. Depending on which grade we assign to your injury, we will adjust our treatment plan accordingly. For example, Grade 1 sprains receive non-surgical treatments, while Grade 3 sprains often require surgery. Below, we explain the different grades of knee sprains. Grade 1: Your ligament sustained mild damage and stretching, but it still maintains your knee’s stability. Grade 2: Also known as a partial tear, your ligament stretches to the point of becoming loose. Grade 3: This is a complete tear of the ligament. The ligament split into two pieces, and the knee’s stability is compromised.