Your doctor will likely ask how you injured your knee, how it has felt since the injury and whether you've injured it before. An exam will include checking for pain or tenderness along the inside of the knee and checking the integrity of your MCL by exerting pressure on the outside of your knee while your leg is both bent and straight.
Depending on the degree of pain or looseness of your knee joint, the injury will be classified as one of three grades:
- Grade 1: There's some tenderness and minor pain at the point of injury.
- Grade 2: There's noticeable looseness in the knee ("opening up" approximately 5 millimeters when manipulated), major pain and tenderness at the inside of the knee, and (in some cases) swelling.
- Grade 3: There's considerable pain and tenderness at the inside of the knee, along with some swelling and marked joint instability (the knee opens up approximately 10 millimeters when manipulated). A grade 3 MCL tear often occurs in conjunction with an ACL tear or, more rarely, with a tear in the posterior cruciate ligament (PCL).
- X-ray: This can show other damage and bone injury.
- Magnetic resonance imaging (MRI): This test is 90 percent accurate for diagnosing MCL injuries and may be ordered if the physical exam findings are unclear or if your doctor suspects other injuries.
- Stress X-ray: This test is similar to a regular X-ray, except the doctor or technician holds the knee open from the side so that any widening of the joint space will be evident on the image.
In some cases, the immediate pain and swelling interfere with the doctor's ability to accurately gauge the injury's severity. If this is your situation, you may be asked to wear a light brace, apply ice and elevate your knee; in time, the swelling and pain will lessen enough to allow diagnosis.
In addition, your doctor may order the following tests:
UCSF Health medical specialists have reviewed this information. It is for educational purposes only and is not intended to replace the advice of your doctor or other health care provider. We encourage you to discuss any questions or concerns you may have with your provider.