What is the unhappy triad of the knee?

The unhappy triad of the knee involves damage to 3 of the major knee ligaments. Remember that this is a significant knee injury that involves complete or incomplete rupture of the anterior cruciate ligament, medial collateral ligament and the medial meniscus.


  • Significant knee pain after a traumatic injury
  • Immediate, intense swelling
  • Discomfort and difficulty when moving the knee
  • Popping or tearing sound at the time of injury
  • Bruising that develops within 2-3 days
  • Instability of the knee joint
    Unhappy triad of the knee

    Significant knee pain after a traumatic injury.

Possible causes of unhappy triad of the knee

It is important to note that the unhappy triad of the knee only occurs after significant force has been placed on the knee. During sports, it tends to be the result of a tackle such as in rugby, football or soccer or in instances where the foot is planted and the knee is twisted. Additionally, it can also occur after vehicular accidents.


Initial care

  • Apply an ice pack over the affected area
  • The individual should rest and support the knee in an elevated position
  • A compression bandage should be used if possible

Once the initial measures are carried out, seek medical care as soon as possible.

Further treatment

An MRI or X-ray is required so that the doctor can confirm a diagnosis. Depending on the severity of the meniscus and ACL tears, surgery is usually an option. In some cases, ACL reconstruction from a graft is carried out. Repair or removal of a meniscus tear is performed at the same time.

The leg affected by the unhappy triad of the knee requires immobilization to promote healing. A rehabilitation program is started to restore full strength and mobility of the joint.

Disclaimer / More Information

The information posted on this page on the unhappy triad of the knee is for learning and educational purposes only. To learn to recognize the indications and manage knee injuries and conditions, register for first aid training at one of our training centers located throughout Canada. The training centers are in Edmonton, Calgary, Vancouver, Kelowna, Surrey, Winnipeg, Toronto, Ottawa and Halifax.


No comments yet.

Leave a Reply

Captcha * Time limit is exhausted. Please reload CAPTCHA.