The knee is the largest joint in the body, and one of the most easily injured. It is made up of four main things: bones, cartilage, ligaments, and tendons. Some of the most common knee injuries include fractures, dislocations, sprains, and ligament tears. 

Ligament injuries in the knee, such as an anterior cruciate ligament (ACL), can put you out of action. They hurt a lot and may limit what you can do. One of the most common knee injuries is an anterior cruciate ligament sprain or tear.

Athletes who participate in high demand sports like soccer, rugby, basketball or netball are more likely to injure their anterior cruciate ligaments.

If you have injured your anterior cruciate ligament, you may require surgery to regain full function of your knee. This will depend on several factors, such as the severity of your injury and your activity level.

Two tell-tale signs of a knee injury are pain and swelling of the knee. You may also have difficulty with the joint moving. It may feel stiff, lock up, or feel like it’s catching as you bend and straighten your leg. 

If you hear your knee pop and then give out at the time of impact, it’s definitely a cause for concern. This popping sound could be the sound of something tearing. You may feel like you can’t stand firmly on your leg after a knee injury, since your ligaments are unstable. It may feel like your knee is giving way. 

What are knee ligaments?

There are 4 major ligaments in the knee. Ligaments are elastic bands of tissue that connect bones to each other and provide stability and strength to the joint. The four main ligaments in the knee connect the femur (thighbone) to the tibia (shin bone), and include the following:

  • Anterior cruciate ligament (ACL) –The ligament, located in the centre of the knee that controls rotation and forward movement of the tibia (shin bone).
  • Posterior cruciate ligament (PCL) -The ligament, located in the back of the knee that controls backward movement of the tibia (shin bone).
  • Medial collateral ligament (MCL) – The ligament that gives stability to the inner knee.
  • Lateral collateral ligament (LCL) – The ligament that gives stability to the outer knee.

How are cruciate ligaments injured?

The anterior cruciate ligament (ACL) is one of the most common ligaments to be injured. The ACL is often stretched and/or torn during a sudden twisting motion (when the feet stay planted one way, but the knees turn the other way). Skiing, basketball, and football are sports that have a higher risk of ACL injuries.

The posterior cruciate ligament (PCL) is also a common ligament to become injured in the knee. However, the PCL injury usually occurs with sudden, direct impact, such as in a car accident or during a football tackle.

Other ligament injuries

  • Collateral Ligament Injuries – Injuries to the collateral ligaments are usually caused by a force that pushes the knee sideways. These are often contact injuries.
  • Meniscal Tears – Sudden meniscal tears often happen during sports. Tears in the meniscus can occur when twisting, cutting, pivoting, or being tackled. Meniscal tears may also occur as a result of arthritis or aging.
  • Tendon Tears – The quadriceps and patellar tendons can be stretched and torn. Although anyone can injure these tendons, tears are more common among middle-aged people who play running or jumping sports.


Treatment for knee ligament injuries

Specific treatment for a knee ligament injury will be determined by your doctor based on:

  • Your age
  • Your overall health and medical history
  • How bad your injury is
  • How well you can tolerate specific medications, procedures, and therapies
  • How long it may take for your injury to heal
  • Your opinion or preference

Treatment may include:

  • Medication such as ibuprofen
  • Muscle-strengthening exercises
  • Protective knee brace (for use during exercise)
  • Ice pack application (to reduce swelling)
  • Surgery


Acute meniscus tears often happen during sports. These can occur through either a contact or non-contact injury—for example, a pivoting or cutting injury.

As people age, they are more likely to have degenerative meniscus tears. Aged, worn tissue is more prone to tears. An awkward twist when getting up from a chair may be enough to cause a tear in an aging meniscus.


You might feel a “pop” when you tear the meniscus. Most people can still walk on their injured knee and many athletes are able to keep playing with a tear. Over 2 to 3 days, however, the knee will gradually become more stiff and swollen.

The most common symptoms of a meniscus tear are:

  • Pain
  • Stiffness and swelling
  • Catching or locking of your knee
  • The sensation of your knee “giving way”
  • Inability to move your knee through its full range of motion


This information is provided as an educational service and is not intended to serve as medical advice. To get specific orthopaedic advice or assistance you need consult Dr Peter Smith or any orthopaedic surgeon.

Thanks to information and resources from: | |

SOURCE: Department of Research & Scientific Affairs, American Academy of Orthopaedic Surgeons. Rosemont, IL: AAOS; February 2014. Based on data from the National Ambulatory Medical Care Survey, 2010; Centers for Disease Control and Prevention.

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