Are the popliteofibular ligament, the arcuate ligament, and the fibular insertion of the popliteus muscle the same structure? An anatomic and terminological study.

Lesions in the lateral region of the knee can result in severe disability due to instability and articular degeneration. The structures in the posterolateral side of the knee function as a unit contributes to rotation and translation limits. Anatomical descriptions of the lateral corner of the knee are incomplete and contradictory. This study aims to verify, through anatomical dissections in cadavers, if the fibular insertion of the popliteus muscle, the arcuate ligament, and the popliteofibular ligament are distinct or the same structure with different terminology and descriptions in the literature. Fifteen cadavers were dissected. Photographs were taken, and in some cases, a video was recorded. Also, the correct terminology for ligament and insertion was searched. The dissections allowed the popliteus muscle to be identified proximally in the lateral femoral condyle, in the fibula head's posterolateral region, and through a meniscocapsular insertion. In none of the anatomy books reviewed, this fibular insertion of the popliteus muscle is mentioned. However, our findings and data from other experimental studies provide evidence of its presence. The aponeurotic portion of the arcuate ligament is distinguished from the short lateral ligament, which is the fibular insertion of the popliteus muscle with its tendinous attachment. Therefore, the term popliteofibular ligament should be abandoned based on the anatomic terminology, and the term "fibular insertion of the popliteus muscle" should be used instead.