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Hinged Knee

Hinged Knee

Medial Collateral Ligament Injuries of the Knee

Medial collateral ligament injuries to the knee are not uncommon. Many well-recognized professional athletes, including Hines Ward, Knowshan Moreno, and Troy Polamalu, have suffered from medial collateral ligament tears after injury on the football field. These can occur alone or in combination with other ligament or cartilage injuries of the knee in athletes.

What is the medial collateral ligament?

The medial collateral ligament (MCL), together with the cruciates and lateral collateral ligament, is critical to the stability of the knee joint. The MCL is a fibrous band of tissue made up of collagen fibers that runs along the inner aspect of the knee from the end of the thigh bone (femur) to the top of the shin bone (tibia). In this location, the MCL provides “side-to-side” stability to the knee and prevents widening of the inner aspect of the joint with forces applied to the outside of aspect of the knee (valgus force). When significant forces are applied to the outside aspect of the knee, as can occur during a tackle in football or awkward slide into base with baseball, the ligament can be stretched (“sprained”) or torn.

The MCL is made up of a superficial and a deep layer. The superficial MCL runs from the distal femur to the tibia 4 or 5 centimeters below the knee joint line, and is found just below the sheath of the sartorius muscle tendon. The deeper MCL layer lies just outside of the knee capsule and inserts directly into the tibial plateau and medial meniscus. The superficial layers is much more mechanically important in resisting forces to the outside aspect of the knee (“valgus” force).

How is the MCL injured in athletes?

Because the MCL resists widening of the inside of the knee joint, the MCL is usually injured indirectly by traumatic forces in the outside of the knee. These are certainly common in contact sports from tackles or “clipping injuries” in football and soccer. However, MCL injuries can also occur from noncontact mechanisms such as awkward landing or pivoting events in basketball or slides into base with baseball. MCL sprains or tears can occur in isolation or in combination with injury to the meniscus, cartilage, or cruciate ligaments.

What are the signs of a medial collateral ligament (MCL) injury in athletes?

The most common symptom following a MCL injury is pain directly over the medial aspect of the knee. The MCL can be tender to palpation over its attachment to the thighbone (femur) proximally, at its mid-substance, or distally over the shin bone (tibia) depending on the location of injury. The pain may also be reproduced by stressing the knee with a force applied to the outside aspect of the knee (“valgus force”), attempting to widen the inner aspect of the joint and stress the MCL. While a valgus force is applied, the inner aspect of the joint line can be palpated – widening that is 5 to 10mm greater than the normal, uninjured knee is significant for MCL injury. Swelling over the torn ligament may appear, and bruising or general swelling of the joint is not uncommon. In more severe injuries, patients may complain that the knee is unstable and feel as though their knee may 'give out' or buckle.

Based on physical examination, MCL injuries are graded in severity on a scale of I to III.

Grade I injuries are incomplete tears of the MCL. The ligament is still intact but stretched, and the symptoms are mild. Patients usually complain of pain with palpation of the MCL.

Grade II MCL tears are partial or incomplete tears of the MCL. There is significant pain with valgus stress of the knee and palpation along the medial aspect on the knee over the ligament. Athletes with these tears often complain of knee pain or instability when attempting to cut or pivot.

Grade III tears are complete tears of the MCL. These athletes have significant pain along the medial aspect of the knee. Even deep bending of the knee is uncomfortable. These tears often occur in combination with other injuries in the knee, and complaints of “giving out” or instability with walking, running, or pivoting is common. A knee brace or a knee immobilizer is usually needed for comfort.

How are MCL injuries in athletes treated?

Treatment of an isolated MCL injury in an athlete rarely requires surgical intervention. Usually rest and anti-inflammatory medications followed by rehabilitation will allow patients to resume their previous level of activity. All MCL injuries, however, are not created equal. Therefore, the time for an athlete to return-to-play is highly variable and dependent on the severity of the injury.

Grade I injuries usually resolve without complication. They are typically managed with rest, ice, and nonsteroidal anti-inflammatory medications until the knee is pain-free to examination or routine activities. Most athletes with a grade I MCL tear will be able to return to their sport within 1-2 weeks following their injury.

When a grade II MCL sprain occurs, a hinged knee brace is commonly used to protect the knee from valgus forces. Nonoperative treatment also ensues with icing, nonsteroidal medications, and controlled rehabilitation. Athletes with a grade II injury can return to activity once they are not having pain to palpation or stressing of the MCL with a valgus force. Athletes can often return to sports within 3-4 weeks after their injury, but may remain in a protective hinged brace with contact sports.

When a grade III injury occurs, the pain usually significant in the acute post-injury period. Athletes usually require a hinged brace locked in extension and crutches to protect against weightbearing for 1 to 2 weeks. As the pain resolves, the brace can be unlocked to allow range-of-motion as tolerated. Gradual weightbearing can be initiated as well. Once the athlete can comfortably flex the knee to 100 degrees, elliptical and stationary bicycle riding can begin. Light running can begin once the athlete has regained their quadriceps strength compared to the opposite side, and sporting activity can follow as long as the athlete remains pain-free. Complete rehabilitation from a grade III MCL tear can range from 6 weeks to 4 months.

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References:

Indelicato, PA. "Isolated Medial Collateral Ligament Injuries in the Knee" J. Am. Acad. Ortho. Surg., Jan 1995; 3: 9 - 14.

Grood E et al. Ligamentous and capsular restraints preventing straight medial and lateral laxity in intact human cadaver knees. J Bone Joint Surg 1981; 63A:1257-1269.