An ACL injury is classified as a grade I, II, or III sprain.
Grade I sprain
The fibers of the ligament are stretched, but
there is no tear.
There is a little tenderness and
The knee does not feel unstable or give out during
Grade II sprain
The fibers of the ligament are partially
There is a little tenderness and moderate
The joint may feel unstable or give out during
Grade III sprain
The fibers of the ligament are completely torn
(ruptured); the ligament itself has torn completely into two parts.
There is tenderness (but not a lot of pain, especially when
compared to the seriousness of the injury). There may be a little swelling or a
lot of swelling.
The ligament cannot control knee movements. The
knee feels unstable or gives out at certain times.
An ACL avulsion occurs when the ACL is torn away from either the
upper leg bone or lower leg bone. This type of injury is more common in
children than adults.
An avulsion fracture occurs when the ACL is torn away from the leg
bone with a piece of the bone.
In this article
This information is produced and provided by the National
Institute (NCI). The information in this topic may have changed since it was written. For the most current information, contact the National
Institute via the Internet web site at http://
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WebMD Medical Reference from Healthwise
April 05, 2012
This information is not intended to replace the advice of a doctor.
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