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anterior cruciate ligament (ACL) injury can involve a
small or medium tear of the ligament, a complete tear of the ligament
(rupture), a separation of the ligament from the upper or lower leg bone
(avulsion), or a separation of the ligament and part of the bone from the rest
of the bone (avulsion fracture). When any of these occur, the lower leg bone
may move abnormally on the upper bone, with a sense of the knee giving
An ACL injury may develop into chronic (long-lasting and recurrent)
The ability of the ACL to control knee movement decreases, resulting in more
sliding of the bones. The knee becomes more and more unstable—it begins to
buckle or give out, sometimes with pain and swelling. This can result in
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) and 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 activities that require a lot of knee stability, rehab may make
your knee stable enough to do daily activities, and you may not need
April 5, 2012
William H. Blahd, Jr., MD, FACEP - Emergency Medicine & Freddie H. Fu, MD - Orthopedic Surgery
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