The collateral ligaments are commonly injured parts of the knee. Ligaments are tough bands of tissue that connect the ends of bones together. There are two collateral ligaments, one on either side of the knee, that limit side to side motion of the knee. The medial collateral ligament (MCL) is found on the side of the knee closest to the other knee. The lateral collateral ligament (LCL) is found on the opposite side of the knee. If an injury causes these ligaments to stretch too far, they may tear. MCL tears are more common than LCL tears.
An injury to these ligaments usually involves a significant force, such as a fall while skiing or a direct impact to the side of the leg. The injury usually occurs when the lower leg is forced sideways, either toward the other knee (medially) or away from the other knee (laterally). For example, a blow to the outside of the knee can result in a tear of the MCL. The LCL is most often injured when the knee is forced to hinge outward away from the body. It can also be torn if the knee gets forcefully snapped backward too far (hyperextended).
An injury that tears one of the collateral ligaments will cause significant damage to the soft tissues around the knee, which will result in bleeding and swelling into the tissues surrounding the knee. The damage may also cause bleeding into the knee joint itself. Both of these scenarios will result in the knee becoming tight, stiff and painful. As the initial stiffness and pain subside, the knee joint may feel unstable, and the knee may give way and not support your body weight. Chronic, or long-term, instability due to an old injury to the collateral ligaments is a common problem. If the torn ligament heals but is not tight enough to support the knee, a feeling of instability will continue to be felt. The knee will give way at times and may be painful with heavy use.
The initial goals of physical therapy will be to decrease the swelling and improve the knee range of motion, as needed. This will be accomplished through a variety of hands-on techniques, exercises, and modalities such as ice and electrical stimulation. In very acute cases crutches may be used to limited weight bearing in order to help the healing process. As your range of motion improves the exercises will be modified with the goal of strengthening the knee, thigh and hip. In addition, your therapist may address any balance deficiencies and may assess your feet to gauge whether foot intervention (ie: custom orthotics) may be beneficial. When you get full knee movement, your strength is improving, and your knee isn't giving way, you'll be able to gradually get back to your work and sport activities.