Layer-by-Layer Anatomy of the Anterolateral Complex of the Knee

Injuries to the anterior cruciate ligament can be associated with anterolateral capsular injuries. Recently, these capsular tears have been suggested to play an important role in rotatory knee instability. A critical review of the anterolateral complex of the knee is necessary to clarify nomenclatures of same structures and the complex anatomy of anterolateral side of the knee. In addition to the lateral collateral ligament and the arcuate complex, the iliotibial band (ITB) is an important lateral structure. It consists of different layers, namely, the superficial, middle, deep, and capsulo-osseous layers. Further, in a subset of patients, a capsular thickening, that is, the mid-third capsular ligament can be observed. Biomechanically, the functional unit of the ITB with its deeper layers between the firm attachment on the distal lateral femoral metaphysis (Kaplan fibers) and Gerdy tubercle was shown to contribute the most to resist internal tibial rotation. Therefore, the ITB and its deeper layers as well as the mid-third capsular ligament should be referred to collectively as the anterolateral complex.