Anterior Meniscofemoral Ligament (Humphrey): Anatomy, Attachments, Relations, Function, Clinical Significance, MRI & CT Imaging

Topic

Anterior meniscofemoral ligament

The anterior meniscofemoral ligament (AMFL), also called the ligament of Humphrey, is a thin but clinically significant structure of the knee joint. It is one of the meniscofemoral ligaments, the other being the posterior meniscofemoral ligament (Ligament of Wrisberg). The AMFL originates from the posterior horn of the lateral meniscus and runs anterior to the posterior cruciate ligament (PCL), inserting onto the medial femoral condyle.

This ligament is important in stabilizing the lateral meniscus and contributes to posterior knee stability in coordination with the PCL. Recognition of this ligament is critical in imaging interpretation, as it may be mistaken for a PCL tear or other intra-articular structures.

Synonyms

Ligament of Humphrey
Anterior meniscofemoral ligament of the knee
AMFL

Origin and Insertion

Origin: Posterior horn of the lateral meniscus
Course: Runs obliquely upward and medially anterior to the PCL within the intercondylar notch
Insertion: Medial femoral condyle, close to the femoral attachment of the PCL

Relations

Anteriorly: Posterior cruciate ligament (PCL), which it crosses in front of
Posteriorly: Posterior meniscofemoral ligament (if present) and posterior capsule
Medially: Medial femoral condyle (site of insertion)
Laterally: Lateral meniscus (site of origin)
Superiorly/Inferiorly: Lies within the intercondylar notch, bounded by femoral condyles

Nerve Supply

Receives innervation from articular branches of the tibial nerve (posterior knee joint capsule)

Arterial Supply

Supplied by branches of the genicular arteries (especially middle genicular artery)

Venous Drainage

Venous return parallels arterial supply into the genicular venous plexus

Function

Provides secondary stabilization to the posterior horn of the lateral meniscus
Assists the PCL in resisting posterior translation of the tibia relative to the femur
Helps distribute forces across the lateral compartment of the knee
Protects the lateral meniscus from excessive shear stress during flexion and rotation

Clinical Significance

May be mistaken for a PCL split or tear on MRI if not recognized
Can be injured in multiligament knee trauma
Presence or absence of the ligament varies among individuals (~30–70% incidence)
Important surgical landmark during knee arthroscopy
Damage may contribute to lateral meniscal instability

MRI Appearance

T1-weighted images:

Appears as a thin, low-signal linear structure crossing anterior to the PCL

T2-weighted images:

Ligament appears as a dark low-signal band against high-signal joint fluid
Discontinuity or irregularity suggests tear

STIR (Short Tau Inversion Recovery):

Normal ligament remains low signal
Injured ligament shows bright hyperintensity with surrounding edema

Proton Density Fat-Saturated (PD FS):

Normal ligament appears as a low-signal band
Partial tears or edema appear as focal bright areas

T1 Fat-Sat Post-Contrast:

Normal ligament enhances minimally or not at all
Injured or inflamed ligament may show focal enhancement

CT Appearance

Non-Contrast CT:

Ligament itself usually not directly visible due to low contrast with surrounding soft tissues
Indirect signs: preserved intercondylar space and intact meniscus

Post-Contrast CT (CT Arthrography):

Ligament may be outlined by intra-articular contrast as a thin, low-attenuation band crossing anterior to the PCL
Tears may appear as irregularity or discontinuity, sometimes with contrast extension into the defect

MRI images