A separation of the ligament from the upper or lower leg bone. This is called an avulsion.
A separation of the ligament and part of the bone from the rest
of the bone. This is called an avulsion fracture.
When any of these occur, the lower leg bone
may move abnormally on the upper bone. It may feel like the knee is giving
An ACL injury may develop into a long-lasting problem called chronic ACL deficiency.
How well the ACL can control knee movement decreases, and this causes more
sliding of the bones. The knee becomes more and more unstable. It starts to
buckle or give out, sometimes with pain and swelling. This can cause
further injury, loss of strength (weakness), and instability. This abnormal knee motion also can damage
cartilage and trap and damage the pads that cushion the knee joints
menisci). It also can lead to premature
ACL surgery is often done for chronic ACL deficiency, unless the knee
is so damaged that surgery won't help. When possible, starting a rehabilitation
(rehab) program before surgery can help speed rehab after surgery.
If you have chronic ACL deficiency and you are willing and able to
stop doing things that require a lot of knee stability, rehab may make
your knee stable enough to do daily activities. You may not need
ByHealthwise Staff Primary Medical ReviewerWilliam H. Blahd, Jr., MD, FACEP - Emergency Medicine Specialist Medical ReviewerFreddie H. Fu, MD - Orthopedic Surgery
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