The strength of the knee comes from four ligaments – one on inside of the knee, one on outside, and two in the middle. The one on inside is called MCL (Medial Collateral Ligament), the one on outside is called LCL (Lateral Collateral Ligament), and the two in the middle of the knee are called cruciate ligaments. Usually, it is only one or sometimes two ligaments which get torn. Rarely, more than two ligaments, and sometimes all the four ligaments are torn.
PCL injury: PCL (posterior cruciate ligament) is a major ligament of the knee. It is situated in the middle of the knee in its posterior part. It is responsible for not allowing the knee to move backward. It may be injured if the knee is hit from the front, for example in a head on crash where something from front hits the knee. Injury to this ligament is not as dramatic, and is missed often. In the past, it was thought that PCL injury can be left as it is, and it does not cause much problem. But, it is now understood that PCL is an important ligament, injury to this ligament needs to be treated by surgical reconstruction in most cases. It is a tricky operation as a part of the operation is done at the back of the knee, an area where important nerves and blood vessels of the leg lie.
MCL (medial collateral ligament) is often injured in a knee bending inward, or when hit from outside. This is one of the easier ligament, as it heals up in most cases by simple rest in brace. When associated with injury to other ligaments such as ACL, or in obese patients, tear of this ligament may also need reconstruction.
Multiple ligament injury to the knee
This severe damage occurs in serious accidents.The knee often dislocates, or becomes severely unstable. It becomes impossible to even move the leg in one piece. Any attempt at putting load on the leg makes the knee give way. In early stages, there is bluish discolouration of the knee due to the blood seeping out under the skin. In severe injuries, there may occur damage to the nerves and vessels of the leg, and may make this injury limb threatening. Patients with low demands can be managed by immobilization and physiotherapy. Those in demanding lifestyle and in sports need surgical reconstruction of ligaments. These operations are hightly specialized, and only few surgeons experienced in this field can perform them well. Post surgery physiotherapy is an important part of overall treatment.