The medial collateral ligament, commonly referred to as the MCL, is a thick and strong ligament located along the inner side of the knee. The MCL stretches from the femur (thighbone to the tibia (shinbone) and helps to stabilize the inner (medial) part of the knee. While several other ligaments and tendons, such as the hamstring tendons, provide additional support, the MCL is the most important structure that prevents the inner part of the knee from “gapping open” when the tibia bone is pulled outward (laterally).
The medial collateral ligament is commonly injured in soccer and football players, as well as skiers, as a result of contact to the outside part of the knee with the foot planted. This subjects the knee valgus force, in which the tibia (shinbone) bends outward relative to the femur (thighbone). Examples include when a football offensive lineman gets “rolled up” by another player from the side or when a soccer player forcefully strikes the inside of the lower leg during a slide tackle. The MCL can be injured at its attachment to the femur, the tibia, or within the ligament itself. The MCL may be injured by itself, but often is injured in conjunction with injury to the anterior cruciate ligament (ACL) and/or the medial meniscus, which is directly connected to the MCL.
Signs of an MCL injury may include pain over the inside part of the knee, swelling, bruising, pain with rotation of the lower leg (such as during pivoting), and a sense of looseness or instability. Some people also describe feeling or hearing a “pop.” For the first few days after the injury, the inner part of the knee can appear swollen and “black and blue” (ecchymotic) and is almost always tender to the touch. The knee may also be unstable. Unlike the ACL, the MCL is not located within the knee joint. Therefore, swelling within the knee joint suggests an associated injury to the ACL and/or meniscus.
If you suspect an MCL injury, it is important to be evaluated by an orthopedic care provider so that the most appropriate treatment can be decided. (Find a doctor at HSS who can diagnose and treat an MCL injury.)
A physician can usually diagnose medial collateral ligament injuries based solely on history and physical examination. Therefore, an X-ray or MRI is not always necessary. However, X-rays of the knee should be considered in teenagers who are suspected to have an MCL injury, because there may also be an associated fracture through the growth plate at end of the femur. MRIs are generally reserved for severe injuries in which surgery is planned or in cases of suspected additional injuries to the ACL and/or meniscus.
MCL injuries are categorized by grades, which are determined by a doctor's findings during the physical exam.
|Grade||Injury||Physical Exam Findings|
|I||Stretching of the MCL||Tender but no instability|
|II||Partial tearing of the MCL||Tender and mild instability|
|III||Complete tearing of the MCL||Tender and considerable instability|
Table 1: Grading of medial collateral ligament injuries
The vast majority of MCL injuries can heal without surgery using conservative methods. The correct treatment will depend upon the severity of the injury, that is whether the ligament is just strained or stretched, versus a partially or completely torn MCL. Rest and bracing are the common nonsurgical treatments. MCL surgery is reserved for cases where the medial collateral ligament fails to heal and restore stability to the inner knee even after a period of rest.
In order to allow healing, the knee should be rested for several weeks. Frequent application of ice and a compressive dressing help to limit swelling in the first few days following the injury. Prior to return to play, the knee should be re-examined to make sure that ligament has healed adequately. A special brace can be used to provide additional support when the player returns to sport.
Several surgical options are available to surgically treat this injury, including MCL repair or reconstruction of the ligament. If the ligament is reconstructed, either the patient’s own tissue or donor tissue is used to construct a new ligament. Both the type of surgery and tissue used will depend upon the injury itself as well as the preference of the surgeon and patient.
Rehabilitation following MCL surgery is quite extensive. A recovery period of at least six months is often necessary prior to returning to vigorous exercise or competitive athletics.
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