Collateral Ligament Injuries of the Knee

Knee ligament sprains or tears are a common sports injury, and athletes who participate in direct contact sports like football or soccer are more likely to injure their collateral ligaments.

Anatomy 

Three bones meet to form your knee joint: your thighbone (femur), shinbone (tibia), and kneecap (patella). Your kneecap sits in front of the joint to provide some protection. Bones are connected to other bones by ligaments. There are four primary ligaments in your knee that act like strong ropes or tethers to hold the bones together and keep your knee stable:

Cruciate Ligaments

These are found inside your knee joint. They cross each other to form an "X" with the anterior cruciate ligament in front and the posterior cruciate ligament in back. The cruciate ligaments control the back and forth motion of your knee.

Collateral Ligaments

These are found on the sides of your knee. The medial or "inside" collateral ligament (MCL) connects the femur to the tibia. The lateral or "outside" collateral ligament (LCL) connects the femur to the smaller bone in the lower leg (fibula). The collateral ligaments control the sideways motion of your knee and brace it against unusual movement.

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Description

As the knee joint relies just on these ligaments and surrounding muscles for stability, it is easily injured. Any direct contact to the knee or hard muscle contraction — such as changing direction rapidly while running — can injure a knee ligament.

Injured ligaments are considered "sprains" and are graded on a severity scale:

• Grade 1 Sprains - The ligament is mildly damaged in a Grade 1 Sprain. It has been slightly stretched, but is still able to help keep the knee joint stable.
• Grade 2 Sprains - A Grade 2 Sprain stretches the ligament to the point where it becomes loose. This is often referred to as a partial tear of the ligament.
• Grade 3 Sprains - This type of sprain is most commonly referred to as a complete tear of the ligament. The ligament has been split into two pieces, and the knee joint is unstable.

The MCL is injured more often than the LCL. Due to the more complex anatomy of the outside of the knee, if you injure your LCL, you usually injure other structures in the joint at the same time (such as a cruciate ligament or capsule tear).

Cause

A force that pushes the knee sideways usually causes injuries to the collateral ligaments. These are often contact injuries, but not always. Medial collateral ligament tears often occur as a result of a direct blow to the outside of the knee, which pushes the knee inwards (toward the other knee). Blows to the inside of the knee that push the knee outwards may injure the lateral collateral ligament.

Symptoms

Symptoms from collateral ligament injury include:

• Pain at the side of your knee. - If there is an MCL injury, the pain is on the inside of the knee; an LCL injury may cause pain on the outside of the knee.
• Swelling over the site of the injury.
• Instability — the feeling that your knee is giving way or unreliable.

Diagnosis

During your initial consultation, A/Prof Woodgate will talk to you about your injury, symptoms and medical history. During the physical examination, all the structures of your injured knee will be examined, and then compared to your non-injured knee. Most ligament injuries can be diagnosed with a thorough physical examination of the knee. Other tests that may help confirm the diagnosis include:

• X-rays - Although they will not show any injury to your collateral ligaments, x-rays can show whether the injury is associated with a broken bone (such as a small fracture from the medial side of the femur).
• Magnetic resonance imaging (MRI) scan - This study creates better images of soft tissues like the collateral ligaments, and can also demonstrate any other adjacent knee injury.

Treatment

Injuries to the MCL rarely require surgery. If you have injured just your LCL, treatment is similar to an MCL sprain. But if your LCL injury involves other structures in your knee, your treatment will address those at the same time.

Nonsurgical Treatment 

• Ice – Applying ice packs to your injury is important in the healing process. The proper way to ice an injury is to use crushed ice directly to the injured area for 15 to 20 minutes at a time, with at least 1-2 hours between icing sessions. 
• Bracing - Your knee must be protected from the same sideways force that caused the injury. You may need to change your daily activities to avoid risky movements. A brace may be used to protect the injured ligament from stress. To further protect your knee, you may be given crutches to keep you from putting weight on your leg.
• Physical therapy - Specific exercises will restore function to your knee and strengthen the leg muscles that support it.

Surgical Treatment

Most isolated collateral ligament injuries can be successfully treated without surgery. If the collateral ligament is torn in such a way that it cannot heal, or is associated with other ligament injuries, surgery may be needed.

Return to Sports

Once your range of motion returns and you can walk without a limp, you may be allowed functional progression, which is a gradual, progressive return to sports activities. For example, if you play soccer, your functional progression may start as a light jog. Then you progress to a sprint, and eventually to full running and kicking the ball.