Torn ACL (Anterior Cruciate Ligament) of the Knee

Medical Author: Benjamin C. Wedro, MD, FAAEM
Medical Editor: Melissa Conrad Stöppler, MD

Do people appreciate how amazing it is that Philip Rivers (quarterback for the San Diego Chargers) played on Sun., Jan. 20, 2008, just six days after having arthroscopic surgery? Aside from the fact that he likely had some cartilage debris cleaned out and the rehab time is measured in weeks, he still had a torn anterior cruciate ligament (ACL).

For regular people and pseudo-athletes, the days after arthroscopic knee surgery are spent reducing knee swelling and starting range-of-motion exercises. This process is hampered by a couple of physiologic barriers.

When the knee is invaded, the muscles around it tend to shut down involuntarily. The quadriceps muscle in the front of the thigh tends to get immediately weaker, and since it is one of the stabilizing muscles of the knee, it is a big deal when this muscle decides not to work. The next barrier has to do with hydraulics. The knee joint has its largest volume of fluid when it's flexed at 15 degrees. When there is even a little fluid, straightening it out combats the law of physics that says "you can't compress fluids."

Medically Reviewed by a Doctor on 12/1/2014

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