An ACL injury -- or other ligament injury -- is sometimes hard to diagnose. Symptoms of a knee ligament injury are:
Pain, often sudden and severe.
A loud pop or snap during the injury.
A feeling of looseness in the joint.
Inability to put weight on the point without pain.
If they're not treated at the time, ACL injuries and other types of ligament injuries may act up months or years later. They can make your knee give out when you twist or pivot.
To diagnose an ACL or other ligament injury, your doctor will give you a thorough exam. If your knee is swollen with blood, your doctor may use a needle to drain it. You may need X-rays, MRI (magnetic resonance imaging) scans, or other tests.
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