What Terrible Triad? An ACL Injury that’s Really an LCL…

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ACL injury

I’m down in the Caymans again, so blogging and time slows down a bit. I did see a patient yesterday that I wanted to share. This is a British gentleman who injured his ACL skiing in Argentina last month. The surgeons he consulted wanted to replace the ACL and the MRI showed only a change in signal in the ACL. While the ACL is commonly injured in skiing and sporting injuries, there’s a terrible “triad” of ACL, MCL, and medical meniscus that make up the most commonly injured knee structures. This means that the inside stabilizing ligament (the MCL) and the inside meniscus (medial meniscus) also get injured in the same events that injure the ACL. I expect that’s what the surgeons and radiologist were looking for and only noticed the ACL injury. However, like a good magician who uses misdirection to conceal how the trick is done, the body is also good at throwing curve balls to physicians. In this case, the my investigative diagnostic exam showed that his LCL (which was read out as normal on the MRI) and not the MCL (as you would expect) was lax. Not just a little loose, but much more lax than his ACL. For example, if his ACL was a 3-/10 severity, his LCL was a 6/10! The lateral collateral ligament is the “duct tape” on the outside of the knee while the MCL is on the inside of the joint. When I looked at the LCL under ultrasound, once it was stressed, the ligament was torn in a very noticeable way. So fixing his ACL would have done little to help his more severe LCL injury. This is likely would have happened if he had undergone surgery, since his LCL looked pretty good on the MRI. The upshot? Using ultrasound to augment an exam beats a static MRI for looking at many ligaments. Using an MRI only for diagnosis is so 20th century…

RegenexxCayman is an independently owned and operated medical services provider operating exclusively in the Cayman Islands and is not part of or affiliated with the Centeno-Schultz Clinic or any U.S. Regenexx Network provider. The Regenexx-C procedure licensed by RegenexxCayman is not approved by the U.S. FDA for use in the United States.

Learn about Regenexx procedures for knee conditions.
Chris Centeno, MD is a specialist in regenerative medicine and the new field of Interventional Orthopedics. Centeno pioneered orthopedic stem cell procedures in 2005 and is responsible for a large amount of the published research on stem cell use for orthopedic applications. View Profile

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