Anterior meniscofemoral ligament (of Humphrey)

The anterior meniscofemoral ligament (aMFL) or ligament of Humphrey is one of two variably present bands of the meniscofemoral ligament.

Gross anatomy

The anterior meniscofemoral ligament inserts to the medial aspect of the intercondylar notch near the posterior cruciate ligament insertion ⁶ and runs between the anterior cruciate ligament (ACL) and posterior cruciate ligament (PCL) to its distal attachment to the posterior horn of the lateral meniscus ^1-3.

Function

The aMFL has been shown to affect the posterior horn of the lateral meniscus during the knee movements by increasing the stability of the meniscus by pulling it in anteromedial direction during flexion. It improves the congruence of the lateral compartment and increases the contact area (decreases the contact pressure). This is especially important in the case of the posterior root of the lateral meniscus tear. Moreover, as the aMFL courses along the PCL, it has a protective role in case of the PCL injury ².

Variant anatomy

The aMFL has been reported to be present in approximately 60% of the knees (cadaveric studies). However, the radiological studies reported its' prevalence to be slightly lower. Interestingly, the MRI studies performed on 3T scanners showed a higher aMFL prevalence (~51%) than the studies performed on 1.5T or lower field scanners (~30%) ³. 

Radiographic features

MRI

This small ligament is best visualized in coronal (oblique longitudinal hypointense structure) and sagittal planes (small, round and hypointense structure located just anterior to the PCL). 

Related pathology

This anatomical variant when present can mimic the tear of the posterior horn of the lateral meniscus (pseudotear) or small loose body in the joint ⁵.