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by Rebecca Fitzgerald, DPT

knee ligament injuryHave you heard the big news? The new discovery in human anatomy? It’s not actually ground-breaking news, but in October 2013 Belgian researchers published in the Journal of Anatomy that they found a new ligament in the knee. It was originally discussed in a publication in 1879 by a French surgeon, but it has been researched little since then.1 Previously known ligaments in the knee include the anterior cruciate ligament (ACL), posterior cruciate ligament (PCL), lateral collateral ligament (LCL), and medial collateral ligament (MCL), all very important in properly stabilizing your knee. The new ligament is called the anterolateral ligament (ALL), and the researchers were able to identify the ligament in 40 of 41 cadaver knees they dissected. It is located toward the outside of the knee and a little toward the front. This is significant because, based on its location, ALL deficiencies may be present with ACL injuries or with iliotibial band syndrome. The Belgian surgeon behind the research says they have been repairing ALL along with ACL repairs, but it is too soon to determine if this has a significant impact in the rehab process or in decreasing the risk for re-rupture of the ACL.2

How did this ligament elude researchers all this time? Well the knee joint is completely covered by a fibrous capsule that holds fluid in so that the knee can move smoothly. The ligaments around the knee, specifically the MCL and LCL, are adjacent to the capsule and sometimes difficult to distinguish as a separate band of fibers. The ALL is similar in that it really is a distinction of part of this fibrous capsule or even part of the iliotibial band, but the research  found it could be consistently identified as a separate structure and has a more particular task in knee stability than the general purpose of the rest of the capsule. More research must be done to determine its exact role in knee stability, but it likely aids in control of tibial internal rotation, which is critical when a person locks and unlocks the knee.1

Keep an ear out for further research as we continue discover more and more about human anatomy and try to understand a little better the why’s and how’s of getting injured. If you have been experiencing knee pain or have any questions about this, come see us at Boston Sports Medicine.

1.  Claes, S., and J. Bellemans. “Journal of Anatomy.” Anatomy of the Anterolateral Ligament of the Knee. 223.4 (2013): 321-28. National Center for Biotechnology Information. U.S. National Library of Medicine, 1 Aug. 2013. Web. 13 Jan. 2014.

2.  Doucleff, Michaeleen. “Surgeons Discover Quirky Knee Ligament All Over Again.” NPR. NPR, 7 Nov. 2013. Web. 12 Jan. 2014.

 Dr. Fitzgerald is a Physical Therapist at Boston Sports Medicine