An expansion of the anatomy of the anterolateral ligament of the knee: Morphological variation and an alternate dissection approach

In 2013, Claes and colleagues documented and described in detail the anterolateral ligament (ALL) of the knee, demonstrating its existence in 97% of their cadaveric samples (40 out of 41). In this study, we sought to further examine the anatomy of this ligament, document its morphological variation in an additional sample of cadaveric knees, and assess the feasibility of its dissection in preserved cadaveric specimens. We dissected the knee joints of 53 (26m/27f) preserved cadaveric knees (paired, when possible), and documented the presence/absence, course, and morphological characteristics of the ALL, as well as collected quantitative data on its length and width. The majority of specimens in our sample (51 out of 53 = 96%) were found to possess a discrete ALL. In our sample, we found support for the hypothesis that the primary function of the ALL is to limit internal (medial) rotation of the tibia. However, we discovered noticeable variation in the insertion of the ligament compared to the originally described pattern. Most notably, it was often found to insert more laterally than has been previously described, closer to the fibular head. This variant would likely result in decreased rotational stability of the knee in individuals with this pattern of insertion. A paired‐samples t‐test revealed highly significant differences between the length of the ALL at extension compared to 90 degrees flexion ( p < 0.001), supporting the idea that the ALL is active during knee flexion. In addition, the originally described dissection technique for identifying and following the ALL requires flexion of the knee, a state which is often not possible in stiff, preserved cadavers. We confirmed the feasibility of an alternate dissection technique in which the quadriceps femoris tendon is incised, for use on specimens in which flexion of the undissected knee is not possible. This technique would be useful for dissection of preserved cadavers used in gross anatomy laboratories, and we discuss the applications of such an approach in student‐led dissections. Support or Funding Information This research was supported by Midwestern University faculty start‐up funds to HFS.