The anterolateral ligament is a rotational stabilizer of the knee joint. It is not always clear what we actually see on MRI in the area of anterolateral ligament (ALL).The aim of the study was to evaluate the ALL variants on MRI images to summarize their common features and differences, and to try to find an explanation for the phenomenon of the ALL variability.200 series of MRI images of knee joints were analyzed. The presence of the ALL, the number of its layers, the relation to the joint capsule, and other anatomical features were assessed.The ALL was visualized on MRI at least partially in 88 % of cases. At least partially two-layer structure was detected in 68 % of all 200 MRI series. The wavy appearance of the certain portions of the anterolateral ligament was observed in some normal knee joints without a history of injuries.Determined that the ALL is a separate anatomical element of the knee joint that has a variable, but in most cases two-layered, anatomical structure and can be detected on MRI in at least 88 % of cases. Axial sections help to identify ALL in complex cases and allow analyzing its anatomy, but adding little in the diagnosis of ALL injury.

Untreated damage to the anterolateral ligament of the knee is one of the residual rotational instability causes in patients with the ruptures of the anterior cruciate ligament after its perfect surgical reconstruction. The contribution of anterolateral ligament damage to rotational instability of the knee, its anatomical features, diagnostics and treatment have been widely discussed in the literature in recent decades. However, the insights in the fundamental issues of its anatomy and functional anatomy, and therefore the reconstruction methods and expediency are diametrically positive. Differences in the anatomy data lead to the uncertainty in diagnostic criteria and optimal treatment options. Anterolateral ligament in its nature is beyond the current-day diagnostic capabilities of magnetic resonance imaging. We have identified the reasons for disagreement among the researchers in the anatomy of an anterolateral ligament, the best ways to diagnose and treat its damage. We have suggested the ways to address these issues in this article.