Medial Collateral Ligament

The medial collateral ligament (MCL) is one of four ligaments that are critical to the stability of the knee joint. A ligament is made of tough fibrous material and functions to control excessive motion by limiting joint mobility. The four major stabilizing ligaments of the knee are the anterior and posterior cruciate ligaments (ACL and PCL, respectively), and the medial and lateral collateral ligaments (MCL and LCL, respectively).
The MCL spans the distance from the end of the femur (thigh bone) to the top of the tibia (shin bone) and is on the inside of the knee joint. The MCL resists widening of the inside of the joint, or prevents "opening-up" of the knee - http://orthopedics.about.com/cs/kneeinjuries/a/mclinjury.htm

Depending on the degree of pain or looseness of your knee joint, the injury will be classified as:


Grade 1: Some tenderness and minor pain at the point of the injury.


Grade 2: Noticeable looseness in the knee when moved by hand; major pain and tenderness at the inside of the knee; swelling, in some cases.


Grade 3: Considerable pain and tenderness at the inside of the knee; some swelling and marked joint instability. The knee opens up about one centimeter (slightly less than half an inch) when the doctor moves your leg around. A grade three MCL tear often occurs along with a tear of the anterior cruciate ligament.

http://www.cedars-sinai.edu/Patients/Health-Conditions/Medial-Collateral-Ligament-MCL-Tears.aspx

Once the pain and swelling subside, you will begin rehabilitation, which will include exercises to restore strength and normal range of motion to your knee. If your knee feels sore while you are doing these exercises, you should proceed slowly to prevent further irritation.


If the torn ligament does not heal sufficiently, you may experience instability in the joint, and you will be more susceptible to re-injury. The MCL usually responds very well to non-surgical treatment, although surgery may be required in rare cases. Depending on the severity of the injury, a period of rest, bracing and physical therapy usually is sufficient to heal the tear.

Once the MCL has healed fully, you should have a minimum of long-term effects, providing there was no other damage to the knee.

http://www.ucsfhealth.org/conditions/mcl_tear/treatment.html