Injuries to this ligament are common. The ACL crosses the center of the knee joint. It connects the femur (thigh bone) to the tibia (shin bone), helping to control knee rotation and forward movement of the tibia. The ACL can stretch or tear during sudden slowing or stopping. It can also be injured while pivoting with the knee with the foot held in one place. Such movements occur often in sports like soccer, basketball and skiing. This ligament can also be injured if there is a direct blow to the knee from one side. This happens in sports like hockey and football.
The first symptoms of an ACL injury may include:

a ‘popping’ sound or sensation
pain (which can be extreme) and difficulty bearing weight
swelling that may start quickly and get worse over hours to days after injury
a feeling of instability, like the knee will give out with walking or turning.

Not everyone experiences all of these problems. Certain symptoms like pain and swelling can also occur with other types of knee injuries.

Posterior cruciate ligament (PCL)

The PCL also crosses the center of the knee joint, just behind the ACL. It balances the ACL by controlling backward movement of the tibia. The PCL is much less likely to be injured than the ACL and usually injured by a direct blow to the tibia below the knee. For instance, hitting the shin against the dashboard in a car crash or falling onto a bent knee during a football game can do damage.

Symptoms of a PCL injury may include:

mild to moderate pain
mild to moderate swelling
a feeling of stiffness and difficulty bending the knee all the way.

Unlike ACL injuries, a pop is not usually heard or felt. Nor is there the same sense of instability. Pain and swelling may be very mild. Instead, there may only be a vague sense that something is wrong.

Medial collateral ligament (MCL)

The MCL is on the medial (or inner) side of the knee. It connects the inner surfaces of the femur and the tibia. The MCL stabilizes the inner side of the knee joint, preventing widening or ‘opening’ of the knee joint on the inside. Injury to the MCL can occur if the outside of the leg, knee, or lower thigh is struck, as when clipped in football. It may also be injured with pivoting or twisting movements in sports like skiing.

Symptoms of a MCL injury may include:

pain and tenderness on the inner area of the knee
swelling and bruising over the inner area of the knee
a feeling of instability in the knee.

The severity of symptoms depends on the extent of the damage. Only with more severe MCL injuries will the knee feel unstable.

Lateral collateral ligament (LCL)

This ligament is on the outside of the knee, opposite the MCL. It connects the lateral (outer) surfaces of the femur with the fibula, the outer bone on the lower leg. It stabilizes the outer side of the knee joint, helping to prevent widening or ‘opening.’ Less likely to be injured than the MCL, a direct blow to the inner surface of the knee can injure the LCL.

Symptoms are similar to that of a MCL injury, except on the outer area of the knee. As with injury to the MCL, severity of symptoms depends on the extent of injury.

It is possible to damage more than one ligament, depending on how the knee is hurt. Other structures in the knee, such as the surface and meniscal cartilage, can also be injured.

Diagnosing injuries

Diagnosing ligament injuries of the knee starts with a thorough history of the injury. Your doctor will ask you several important questions. These may include the following.

How long ago did the injury happen?
What were you doing when you hurt your knee?
How did you hurt your knee? For instance, did your knee twist? Were you hit by someone else?
Did you hear or feel a pop?
Was there any swelling? How much? How quickly did the knee swell?
Does your knee feel unstable?

Your doctor may ask other questions about your medical history and any previous knee injuries.

Next, the knee will be examined. Your doctor will assess the amount of knee swelling, range of motion, and location of pain. Several different tests can check the ligaments. Doctors often compare a hurt knee to the uninjured one.

Questioning and a physical exam can diagnose most ligament injuries. A doctor may sometimes order diagnostic imaging tests like x-ray, ultrasound, bone scan or MRI to further evaluate the injury.

Treating injuries

Initial treatment for most ligament injuries involves controlling pain and swelling, and recovering knee range of motion. Changing your activities, resting, and applying ice is usual. Pain killers or anti-inflammatory medications may be recommended. Depending on the ligament injured and the amount of damage, other treatment options may include:

wearing a brace
physiotherapy
referral to an orthopedic surgeon to assess your need for surgery.

In considering surgery, you and your doctor will discuss:

the ligament that has been injured and whether other knee structures are involved
your age
your sporting activities and level of competitiveness
the type of work activities you do
your expectations of knee function
your overall health.

Even with a serious injury, with appropriate treatment it is usually possible to fully recover and return to most sport and work activities. Your doctor can discuss in detail a treatment plan that works for you.

Preventing knee ligament injuries

There is growing evidence that you can train your body to avoid some knee ligament injuries. This is particularly true for ACL injuries. Exercises that may help include those that:

increase overall aerobic fitness levels to avoid early fatigue
strengthen the quadriceps and hamstrings (the muscles of the front and back of the thigh)
focus on balance and proprioception (the ability to sense the position, location and movement of our body parts)
focus on your ability to jump and land safely with proper technique.

Discuss a suitable exercise program with your doctor or certified personal trainer.

Injuries to Knee Ligaments Treat problems and avoid future damage