The unhappy triad is a severe injury which involves damage to three of the four major ligaments in the knee. This is a major knee injury that often occurs after a severe impact.
[the_ad id=”41049″]What is the Unhappy triad injury?
The unhappy triad, also known as the terrible triad, or O’Donoghue triad is a severe knee injury. It involves full or partial tears of the:
What are the Symptoms?
- Extreme pain in the knee after a traumatic injury.
- Rapid, extreme swelling.
- A popping or tearing sound at the time of injury.
- Difficulty and pain on trying to move the knee.
- Bruising usually appears within 2-3 days.
- An unstable feeling knee.
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What Causes an Unhappy Triad?
This kind of injury will only occur after a considerable force has been applied to the knee. In sports, it tends to be a result of a tackle (such as football, rugby or soccer), or occasionally where the foot is planted and the knee is twisted. They may also happen after car accidents.

- The anterior cruciate ligament crosses the middle of the knee and prevents forward movement of the tibia (shin bone).
- The medial ligament is on the inside of the knee and prevents sideways movement of the knee joint.
- Part of the medial meniscus on the inside of the knee attaches to the medial ligament. Therefore it is often torn with a bad medial ligament sprain.
Treatment
Immediate Treatment
- Apply ice or cold therapy.
- Rest and support the knee in an elevated position.
- If possible use a compression bandage.
- Seek medical help as soon as possible.
Further Treatment
- An X-ray or MRI will usually be taken to confirm the diagnosis.
- Depending on the severity of the ACL and meniscus tears, surgery will usually be advised.
- ACL reconstruction from a graft is performed. The graft is usually taken from the hamstrings or patella tendon.
- A meniscus tear repair or removal is performed at the same time.
- The MCL is usually left to heal naturally.
- The leg will be immobilized to allow healing.
- A lengthy rehabilitation programme is then required to regain full strength and mobility at the knee