Later this month of November, forty of our St.Vincent Sports Performance, NATABOC certified athletic trainers will spend a full day in an intentional academic learning laboratory. The environment is a controlled cadaver lab. Expert leaders from academia and practicing musculoskeletal surgeons will lead the dissections and discovery. It will be a robust day of new learning, re-acquaintance with learnings from past sessions and a deeper dive into the layers under the surface.
In light of the announcement in the Journal of Anatomy of the “new” body part in the assembly of the knee joint, this is a timely work session. It causes me to reflect upon my past anatomy sessions, both cadaver, in surgery and in practice, of topical evaluations and palpations. I recall “my” cadaver at Tufts University in Boston being void of a plantaris muscle of the lower leg as well as a pronounced sciatic nerve, which bifurcated the piriformis muscle of the hind quarter. Our teachers spent much time in narrative of the variations of the human body based upon origin, age and gender.
Therefore, this “discovery” does not tilt my world. Rather, it reminds us as practitioners of the evolution and adaptation of the human body. It also should cause us to reflect that the human body is not a textbook, cookie-cutter in real life, as seen in the books of anatomy.
J Anat. 2013 Oct;223(4):321-8. doi: 10.1111/joa.12087. Epub 2013 Aug 1.
Anatomy of the anterolateral ligament of the knee.
Claes S, Vereecke E, Maes M, Victor J, Verdonk P, Bellemans J.
Source: Department of Orthopedic Surgery & Traumatology, University Hospitals Leuven, Leuven, Belgium.
In 1879, the French surgeon Segond described the existence of a ‘pearly, resistant, fibrous band’ at the anterolateral aspect of the human knee, attached to the eponymous Segond fracture. To date, the enigma surrounding this anatomical structure is reflected in confusing names such as ‘(mid-third) lateral capsular ligament’, ‘capsulo-osseous layer of the iliotibial band’ or ‘anterolateral ligament’, and no clear anatomical description has yet been provided. In this study, the presence and characteristics of Segond’s ‘pearly band’, hereafter termed anterolateral ligament (ALL), was investigated in 41 unpaired, human cadaveric knees. The femoral and tibial attachment of the ALL, its course and its relationship with nearby anatomical structures were studied both qualitatively and quantitatively. In all but one of 41 cadaveric knees (97%), the ALL was found as a well-defined ligamentous structure, clearly distinguishable from the anterolateral joint capsule. The origin of the ALL was situated at the prominence of the lateral femoral epicondyle, slightly anterior to the origin of the lateral collateral ligament, although connecting fibers between the two structures were observed. The ALL showed an oblique course to the anterolateral aspect of the proximal tibia, with firm attachments to the lateral meniscus, thus enveloping the inferior lateral geniculate artery and vein. Its insertion on the anterolateral tibia was grossly located midway between Gerdy’s tubercle and the tip of the fibular head, definitely separate from the iliotibial band (ITB). The ALL was found to be a distinct ligamentous structure at the anterolateral aspect of the human knee with consistent origin and insertion site features. By providing a detailed anatomical characterization of the ALL, this study clarifies the long-standing enigma surrounding the existence of a ligamentous structure connecting the femur with the anterolateral tibia. Given its structure and anatomic location, the ALL is hypothesized to control internal tibial rotation and thus to affect the pivot shift phenomenon, although further studies are needed to investigate its biomechanical function.
To investigate the knee, lead author Steven Claes and his team performed macroscopic dissections of 41 cadaveric knees. In all but one of the knees, the researchers found that a “pearly band” was a well-defined, clearly distinguishable structure connecting the femur to the anterolateral tibia. The structure, dubbed the “anterolateral ligament” (ALL), is located in the so-called anterolateral aspect of the knee.
According to the researchers, the existence of the ALL helps explain why patients with ACL injuries continue to experience complications after surgery and treatment. For example, many complain about “pivot shifts” that cause their damaged knee to give way. “By providing a detailed anatomical characterization of the ALL, this study clarifies the long-standing enigma surrounding the existence of a ligamentous structure connecting the femur with the anterolateral tibia,” the study authors wrote in their conclusion. “Given its structure and anatomic location, the ALL is hypothesized to control internal tibial rotation and thus to affect the pivot shift phenomenon, although further studies are needed to investigate its biomechanical function.”
The ALL is not the only new addition to next year’s anatomy books! In July, a similar research effort identified an entirely new layer of the human cornea, ‘Dua’s Layer’.
Executive Director, St.Vincent Sports Performance