“New” Ligament Discovered in the Knee

Written by admin on January 6, 2014 – 2:18 pm -

In October, a group of physicians in Belgium released a study that gives support to the idea that there may be an additional ligament present in the knee. Ligaments, as we know, connect bone to bone and lend stability to a joint. Previously, we had only really concerned ourselves with the four largest ligaments in the knee, the lateral collateral ligament (LCL), the medial collateral ligament (MCL), the posterior cruciate ligament (PCL), and the one you’ve probably heard the most about, the anterior cruciate ligament (ACL).

Building off of the work of a French surgeon, Paul Segond, that dates back to 1879, these surgeons worked with 41 cadavers and microscopic dissection techniques to visualize a small band of connective tissue that runs from the front, outside portion of the femur to tibia and so appropriately named it the anterolateral ligament, or ALL. They were able to identify what they believe to be the ALL in 40 of the 41 human specimens. Researchers believe that this ligament could help support movements that involve pivoting and change of direction, and thus, could also be torn under these same stresses. Because the ACL is also commonly torn as a result of excessive rotational stresses, it is hypothesized that these two ligaments could be sprained concurrently. The surgeons also speculate that because no effort previously has been made to restore function in this ligament during surgery to replace the ACL, that the ALL could be to blame in cases that have less-than-optimal outcomes where patients have continued complaints of instability and lack of full function in the knee. Orthopedic experts around the world have had mixed reactions to this news, but all agree the work is intriguing and they are interested to see the direction further research will take the field.

While its location and potential role in lower extremity biomechanics are becoming increasingly elucidated, there are still many questions that remain. For instance, what is the healing potential of the ALL? Does it even have the potential to heal on its own, similar to the MCL (small tears usually heal with rest, larger or complete tears often warrant reconstruction)? If it is possible to reconstruct, what kind of graft would be amenable to this and what surgical techniques would be used? And then, a few obvious questions: Why haven’t we seen this ligament before? What about the tens of thousands of ACL tears that are surgically reconstructed every year with excellent outcomes where individuals are able to return to their daily and athletic activities? And ultimately, would it even respond to reconstruction in that it could help to restore function and thus result in better outcomes?
This “discovery” must be accorded its proper place in our current compendium of knowledge. It is important not because a “new” ligament has been discovered but rather suggests a more important role for a ligament long-ago discovered but not accorded any particular significance. More investigation into the role and healing capacity of this ligament is certainly warranted.

Alex Vitek is a nationally Certified, state Licensed Athletic Trainer and post-graduate Resident in training at The Galland Orthopaedics and Sports Medicine Athletic Training Residency– a 12 month immersional program allowing ATCs to maintain and hone clinical skills while developing those talents necessary to be effective in the clinical setting as an ATC/physician extender. Find out more at www.atcfellowship.com

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