What is the ligament of Humphrey in the knee?

The Ligament of Humphrey in the Knee

The ligament of Humphrey, also known as the anterior meniscofemoral ligament (aMFL), is a fibrous band of connective tissue that attaches between the lateral aspect of the medial femoral condyle and the posterior horn of the lateral meniscus, running posterior to the anterior cruciate ligament (ACL) and anterior to the posterior cruciate ligament (PCL). 1

Anatomical Characteristics

The ligament of Humphrey has the following key anatomical features:

• Location: Runs from the lateral aspect of the medial femoral condyle to the posterior horn of the lateral meniscus
• Position: Passes posterior to the ACL and anterior to the PCL
• Prevalence: Present in approximately 55.5% of knees according to meta-analysis data 1
• Size:
  • Mean width: 5.09 ± 1.41 mm in males and 2.99 ± 1.29 mm in females
  • Mean length: 27.09 ± 2.15 mm in males and 24.38 ± 3.39 mm in females 2

Clinical Significance

The ligament of Humphrey has important functional and clinical implications:

1. Knee Stability: It contributes to the stabilization of the lateral compartment of the knee joint 1

2. Meniscal Stabilization: In ACL-deficient knees with posterior lateral meniscus root injuries, the meniscofemoral ligaments (including Humphrey's ligament) may help stabilize the lateral meniscus against extrusion 3

3. Biomechanical Function:

   • Different portions of the ligament are taut at different degrees of knee flexion and extension
   • Works with other ligaments to contribute to the "screw-home mechanism" of the knee 4

4. Relationship with Other Structures: Has an intimate relationship with the PCL, popliteus muscle, and lateral meniscus 4

5. Potential Pathology: Can be a site of pathology, such as intra-articular ganglion cysts 5

Clinical Implications

Understanding the anatomy of the ligament of Humphrey is important for:

• Accurate diagnosis and treatment of ligamentous knee injuries
• Proper planning and execution of knee surgeries, including ACL reconstruction
• Assessment of lateral meniscus stability, particularly in cases of ACL deficiency
• Interpretation of MRI findings in knee injuries

Imaging Considerations

• MRI is the preferred imaging modality for visualizing the ligament of Humphrey
• Higher detection rates are seen with 3.0-T MRI compared to lower field strengths 1
• Arthroscopic studies report the highest prevalence (82.3%) compared to imaging studies 1

Anatomical Variations

• Significant variability exists in the prevalence and morphology of the ligament
• Anatomical variations are present in approximately 38% of knees, with higher frequency in females (62.5%) than males (37.5%) 2
• The ligament may be absent in some individuals, but at least one meniscofemoral ligament (either Humphrey or Wrisberg) is typically present in every knee 2

Understanding the ligament of Humphrey is essential for orthopedic surgeons and radiologists involved in knee assessment, as its presence and integrity may influence treatment decisions in cases of complex knee injuries, particularly those involving the ACL and lateral meniscus.