Bones are connected to other bones by ligaments. They act like strong ropes to hold the bones together and keep your knee stable. There are four primary ligaments in your knee.
Medial and Lateral Collateral Ligaments, located on the side of the knee. They control the sideways motion of your knee and brace it against unusual movement.
Anterior Cruciate and Posterior Cruciate Ligaments form a cross inside the knee joint. The cruciate ligaments control the back and forth motion of your knee.
About half of all injuries to the anterior cruciate ligament occur along with damage to other structures in the knee, such as articular cartilage, meniscus, or other ligaments. 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, as well.
The anterior cruciate ligament can be injured in several ways:
Changing direction rapidly
Landing from a jump incorrectly
Direct contact or collision, such as a football tackle
When you injure your anterior cruciate ligament, you might hear a "popping" noise and you may feel your knee give out from under you. Other typical symptoms include:
Pain with swelling. Within 24 hours, your knee will swell. If ignored, the swelling and pain may resolve on its own. However, if you attempt to return to sports, your knee will probably be unstable and you risk causing further damage to the cushioning cartilage (meniscus) of your knee.
Loss of full range of motion
Tenderness along the joint line
Discomfort while walking
Pain at the sides of the knee. If there is an MCL injury, the pain is on the inside of the knee. If it is an LCL injury the pain is on the outside of the knee.
Common Management Techniques
Injuries to the MCL rarely require surgery and are often treated with a hinged brace.
If you have injured just your LCL, treatment can be similar to an MCL sprain, but surgery may be recommended, especially in cases where the ligament has pulled directly off the bone. If your LCL injury involves other structures in your knee, your treatment will address those, as well.
Ice. Icing your injury is important in the healing process. The proper way to ice an injury is to apply crushed ice directly to the injured area for 15 to 20 minutes at a time, with at least 1 hour between icing sessions. Chemical cold products (blue ice) should not be placed directly on the skin and are not as effective.
Bracing. Your knee must be protected from the same sideway force that caused the injury. You may need to change your daily activities to avoid risky movements. To further protect your knee, you may be given crutches to keep you from putting weight on your leg.
Physiotherapy. Your doctor may suggest strengthening exercises. Specific exercises will restore function to your knee and strengthen the leg muscles that support it.
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, your doctor may suggest surgery to repair it. Your surgeon will discuss which technique of repair is best for you.
Once your range of motion returns and you can walk without a limp, your physio may allow functional progression. This 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. Your doctor may suggest a knee brace during sports activities, depending on the severity of your sprain. There will be several stages to your recovery with your treatment being progressive in nature and closely monitored by your Physiotherapist.