The medial collateral ligament (MCL) connects the medial epicondyle of the femur to the medial tibia and as a result resists medially directed force at the knee. The MCL is primary stabilizer of the medial side of the knee against valgus force. This extra-articular ligament is a thick and flat band which attaches proximally on the medial femoral condyle and extends to the medial surface of the tibia approximately six centimeters below the joint line.
The medial collateral ligament is comprised of two parts. A deep part of the ligament attaches to the cartilage meniscus and the superficial part attaches further down the joint A grade 2 injury of the MCL is characterized by partial tearing of the ligament fibers resulting in joint laxity when the ligament is stretched A grade 3 MCL sprain would result in complete tearing of the ligament. Often the medial capsular ligament is involved in a grade 2 sprain MCL.
Individuals participating in contact activities requiring a high level of agility are particularly susceptible to a MCL injury, particularly skiing, soccer, and football. Mechanism of injury is usually a blow to the outside of the knee joint causing excess force to the medial side of the joint. The MCL can also be injured by twisting of the knee. Muscle weakness resulting in poor dynamic stabilization may also increase the incidence of this type of injury.
A patient with a grade II MCL injury will likely present with an instability to fully extend and flex the knee, pain and significant tenderness along the medial aspect of the knee, possible decrease in strength, and painful limp. There is typically instability with the joint, and slight to moderate swelling around the knee. More severe swelling may be indicative of meniscus or cruciate ligament involvement.
MRI is a noninvasive imaging technique that can be utilized to view soft tissue structures as ligaments. The imaging technique is extremely expensive and therefore may not be commonly employed on an individual with a suspected MCL injury without other extenuating circumstances. A valgus stress test is a technique designed to detect medial instability in a single plane. The examiner applies a valgus stress at the knee while stabilizing the ankle in slight lateral rotation. The test is often performed initially in full extension and then in 30 degrees of flexion. A patient with a grade 2 MCL sprain may exhibit 5-15 degrees of laxity with valgus stress at 30 degrees of flexion.
ACL and or meniscal damage often accompanies a grade 2 MCL injury. As a result it is often prudent to perform special tests directed at these particular structures. The MCL normally has a good secondary support system with weight bearing forces compressing the medial side of the joint and adding to the overall stability of the joint. This allows the structures to be protected after injury along with the use of a brace. Physical Therapy intervention should be directed towards increasing range of motion in the involved extremity and beginning light resistive exercises. Range of motion exercises may include heel slides or stationary cycling without resistance. Resistive exercises should be directed towards the quadriceps and may include isometrics and closed kinetic chain exercises. Functional activities such as gait and stair climbing should be incorporated into the treatment program.
A grade II MCL sprain should progress fairly quickly if no other structures are involved A patient should be able to return to their previous functional level within four to eight weeks following the injury. Proper healing time and rehab management should allow the patient to return to all forms of activity once the patient demonstrates full range of motion, ambulation without a limp, no visual swelling, and competence with all agility testing. If the patient has residual laxity from the injury the patient may be susceptible to reinjury.