To determine the severity and laxity of the knee the therapist can carry out a varustest. To determine whether it is a grade 2 sprain or 3, you can take the test in extension. When the patient has a severe grade 3 sprain, the knee will show laxity, while a grade 2 sprain won’t. Also the grade 3 sprain will not have a demonstrable endpoint at 30 degree flexion.[16]When the varustest is done in extension, there is also an evaluation of the posterolateral corner structures and cruciate ligaments. [11]
You can also take an MRI scan of the knee. It is an accurate way to see how badly the lateral collateral ligament has been torn and to detect other injuries to the knee. Noticing a partial rupture with an MRI scan is difficult. To make sure that the bones of the knee are not broken, you can take an X-ray.[1][5][9][17]
The peroneal nerve can also be injured. This type of injury requires surgical repair because of the complex structures which are involved. Damage is easily spotted if you see a foot drop of the patient while he is walking or when the patient feels a numbness or weakness in the foot. [1][18]