Two sets of ligaments in the knee give it stability: the cruciate and the collateral ligaments. These short bands of tough fibrous connective tissue connect the thighbone (femur) and shinbone (tibia) and give the joint strength and stability. An injury to a ligament is referred to as a sprain, a partial tear or a total tear.
There are two collateral ligaments:
- The medial collateral ligament (MCL) runs alongside the inner side of the knee and limits side-to-side movement.
- The lateral collateral ligament (LCL) runs alongside the outer side of the knee and limits side-to-side movement.
What causes a collateral ligament tear?
The most common knee ligament injured is the MCL. Injury usually occurs after a blow to the outside of the knee. A direct hit to the outside of the knee in football or hockey may cause the MCL ligament on the inside of the knee to be injured.
The LCL is the least likely of the knee ligaments to be injured. If a LCL injury does occur, it likely happens in a sports match such as football, soccer or wrestling when one player falls onto the inside of another player’s leg, the foot of which is planted.
Collateral ligaments may also be injured when a person lands badly from a jump, causing the knee to be forced sideways by the weight of the body.
What are the symptoms of a collateral ligament tear?
When a collateral ligament is torn, the person may feel a pop in the knee and the knee may buckle sideways.
If a collateral ligament has been injured, the symptoms include the following:
- Pain over the injured ligament.
- Mild to moderate swelling.
- Limited range of motion.
- Feeling of instability in the knee if the ligament is badly or completely torn.
How is a collateral ligament tear treated?
Many partial collateral ligament strains or tears will heal on their own with the proper care. Almost always, the first treatment for a tear—no matter how severe—is non-surgical.
Once a tear has been diagnosed, the physician will first prescribe non-surgical treatments. Those treatments usually include the following:
- RIC–rest, ice, compression and elevation.
- Anti-inflammatory medications.
- Physical rehabilitation of the knee with exercises to strengthen the muscles supporting the knee and stretches to improve the knee’s range of motion.
- Bracing to control joint movement.
If the collateral ligament is torn in such a way that the ligament fibers cannot heal, surgery may be required. This is quite rare, actually.
Ligament reconstruction involves replacing the torn ligament with a tendon graft that is usually taken from elsewhere in the patient’s knee or leg. The graft is held in place with screws.
Physical therapy and rehabilitation are required following surgery for a person to return to a normal lifestyle. In addition, the patient may be required to wear a knee brace while the knee is rehabilitated.
The cruciate ligaments are short but strong rounded bands that cross each other through the knee, forming a stabilizing X within the joint.
There are two cruciate ligaments:
- The anterior cruciate ligament (ACL) limits rotation and forward movement of the tibia.
- The posterior cruciate ligament (PCL) limits backward movement of the tibia
An injury to a cruciate ligament is often called a sprain when the ligament is simply stretched. There also may be a partial tear or, in the case of a rupture of the ligament, a total tear. Sometimes a person may experience an avulsion fracture when the ligament and part of the bone separate from the rest of the bone.
The more common of the two cruciate ligament injuries is the ACL tear.
What causes a cruciate ligament tear?
The ACL can be injured in several ways, such as when a person changes directions quickly, quickly slows down when running or lands badly from a jump. Any sudden twisting motion when the feet are planted one way the knees turn another way can stretch or tear the ACL. It also may be injured by a forced hyperextension or direct blow to the lower back of the leg, causing the tibia to move forward.
The PCL is most often injured by direct impact, such as in a football tackle or an automobile accident.
What are the symptoms of an ACL tear?
If a person suffers a sudden, severe ACL injury, the symptoms include the following:
- A popping sound or feeling of a pop at the time of injury, with the knee giving out or buckling sideways.
- Pain, which likely will worsen, especially when trying to stand.
- Swelling of the knee joint within the first few hours after injury.
- An inability to bend or straighten the knee completely because of swelling and pain.
- Loss of strength in the leg muscles.
If an ACL injury develops into a long-lasting and recurrent or chronic problem, the patient may have an ACL deficiency. This often occurs if an ACL injury has not been treated in the past or it has been treated unsuccessfully. The symptoms may include a knee that buckles or gives out occasionally, sometimes with pain and swelling. Over years this may lead to “wear and tear” arthritis.
Sometimes, especially in contact sports, ACL injuries are combined with damage to the menisci and MCL. This is often referred to as the “unhappy triad.”
How is an ACL tear treated?
When the ACL is injured, the first thing a person should do, even before seeing a physician, is to take steps to reduce the inflammation and pain.
This is best done by following the principles of RICE: rest, ice, compression and elevation. The injured person should also use crutches to avoid putting pressure on the joint and possibly causing further damage to other structures in the knee.
Once a sprain or tear has been diagnosed, the physician will first prescribe non-surgical treatments. Those treatments usually include the following:
- Continued use of RICE–rest, ice, compression and elevation.
- Anti-inflammatory medications.
- Extensive physical rehabilitation of the knee with exercises to strengthen the muscles supporting the knee and stretches to improve the knee’s range of motion.
- Bracing to control joint movement.
Once torn, the ACL is not likely to heal on its own. Surgery may be required to reconstruct the ligament.
Most ACL surgery involves replacing the ACL with a piece of tendon taken from elsewhere in the patient’s body. Often this tissue graft is a strip of tendon taken from the patient’s knee (patellar tendon) or another leg muscle, such as the quadriceps or hamstrings. After the torn ligament is removed, the new tendon is weaved through the joint and secured to the thighbone and the shinbone. Another option is to use tissue from a cadaver (allograft) that is specially prepared.
In many cases, the surgeon will choose arthroscopic surgery. Arthroscopic repair makes use of a fiberoptic scope connected to a video camera and small, specialized instruments. In this surgery, the scope and instruments are inserted into small puncture-type incisions rather than through a larger open incision. Sometimes arthroscopic surgery is not feasible and the surgeon must make an incision to open the knee, especially if there is damage to other parts of the knee as well.
Extensive physical therapy and rehabilitation for 4 to 6 months is required for the patient to return to a normal lifestyle. In addition, the patient will be required to wear a special knee brace for several months while the knee is rehabilitated.