Medial collateral ligament (MCL) injury
The medial collateral ligament of the knee is easily damaged by tackles, etc.
The medial collateral ligament of the knee (MCL) gets injured most frequently of all ligament injuries and is often recognized simply as a knee sprain. If it is fixed appropriately in an early stage, it could be repaired more easily (compared with anterior cruciate ligament rupture). But when it becomes chronic (being stretched without treatment in the acute stage), it could cause complications such as meniscal injury, therefore appropriate treatment is essential.
Cause and mechanism of onset
The MCL consists of three layers: the superficial layer, the deep layer, and the posterior oblique ligament. The MCL runs from the medial femoral epicondyle to the medial tibia of the medial knee joint, with the range of a length of 10 cm and a width of 3 cm.
Cause of the injury
In contact sports, such as rugby, American football, football (soccer) , and basketball, external forces (tackles) from the lateral to the medial aspect of the knee may cause the MCL to become overly tense and eventually more susceptible to rupture when valgus or external rotation forces are applied to the joint. The injury may also occur when falling in skiing, jump landing or twist.
In tenderness, swelling, a feeling of warmth and load on the medial joints, valgus laxity (as like X leg) are identified. Immediately after the injury, joint hematoma is present. On the other hand, when it becomes chronic, edema is present.
In general, the injuries are classified into three types and the classification is utilized for treatment guide.
Grade I: no laxity (compared to the unaffected side), and ligament tenderness is predominant
Grade II: valgus laxity in extension (-), valgus laxity (+) in 30 degrees flexion
Grade III: valgus laxity (+) in extension and valgus laxity (+) in 30 degrees flexion
As the X-ray does not show the ligaments, the purpose is to check for fractures. Stress X-rays (Photo 1) and instrumental checks are helpful to determine the degree of injury. Magnetic resonance imaging (MRI) is the most helpful inspection and enables to confirm not only MCL injuries, but also ACL and meniscal injuries as well as hemorrhage.
Photo 1: Distraction of the medial joint by an X-ray with MCL rupture
Although also the isolated injuries occur in common, the injuries on the anterior cruciate ligament (ACL), posterior cruciate ligament (PCL), or medial (lateral) meniscus could be caused. Combined injury of the ACL, MCL and medial meniscus is also called the unhappy triad.
Treatment and rehabilitation
RICE therapy is usually given in grade I and conservative treatment by immobilization is done in grade II. Anti-inflammatory analgesics and physical therapies such as ultrasound and low-frequency therapy are used to control pain. Primary suturing of the ligament is performed for grade III injuries and combined anterior cruciate ligament (ACL) and meniscal injuries. Conservative treatment with cast immobilization and nowadays brace immobilization has been used for isolated injuries with good results.
In the initial stage, trainings on unaffected side and trunk of upper extremity are performed such as isometric training, straight leg raising ( SLR training) and simultaneous contraction exercises of flexor and extensor around the knee. Because a pain tends to be relieved three weeks after injury, the person may gradually begin to perform range of motion (ROM) of the knee joint and gait exercises with a brace.
Isolated injuries are relatively stable with appropriate immobilization in the initial stage, but they are more likely to loosen when being associated with ACL injury. Loosening of the MCL may occur meniscal injury afterward.
Accurate diagnosis based on injury level and appropriate fixation are important at the time of injury.