The anterolateral ligament of the knee: A dissection study

• The ALL is a distinct structure in the anterolateral knee compartment.
• The ALL is present in almost half of the cases.
• The ALL should not be confounded with the capsular–osseous layer of the ITB.
• The capsular–osseous layer has a similar course but a different origin than the ALL.
• The ALL might play an important role in rotational knee stabilization.

BackgroundRecent studies have described the presence of the anterolateral ligament (ALL). However, there is still no consensus regarding the anatomy of this structure with the topic controversially discussed. The aim of this study was to provide an anatomical description of the ligamentous structures on the anterolateral side of the knee with special emphasis on the ALL.MethodsForty-four human cadaveric knees were dissected to reveal the ALL and other significant structures in the anterolateral compartment of the knee joint. The ALL was defined as a firm structure running in an oblique direction from the lateral femoral epicondyle to a bony insertion at the anterolateral tibia.ResultsThe ALL was identified in 45.5% (n = 20) of the dissected knee joints. The structure originates together with the fibular collateral ligament (45%) or just posterior and proximal to it (55%). The ligament has an extra-capsular, anteroinferior, oblique course to the anterolateral tibia with a bony insertion between Gerdy's tubercle and the fibular head. The ALL had its greatest extend at 60° of knee flexion and maximal internal rotation.ConclusionThe ALL is a firm ligamentous structure in the anterolateral part of the knee present in 45.5% of the cases. Given the course and characteristics of this structure, a function in providing rotational stability by preventing internal rotation of the knee is likely.Clinical relevanceThe ALL might be an important stabilizer in the knee and may play a significant role in preventing excessive internal tibial rotation and subluxation of the knee joint.