Ligamentum mucosum

The ligamentum mucosum (Infrapatellar plica) is a ligamentous structure within the synovial layer of the knee joint capsule. It is composed of dense regular connective tissue and extends from the distal femur to the infrapatellar fat pad. Histological analysis has confirmed the presence of small peripheral nerves at the junction between the ligamentum mucosum and the fat pad.[1]

Anatomically, the ligamentum mucosum can be classified into different types based on its attachment points. According to a study, three types have been identified:

• Type I (single band with attachment to the intercondylar notch)

• Type IIa (bifurcated ligament with attachment to the anterior cruciate ligament)

• Type IIb (bifurcated ligament with both attachments to the intercondylar notch).

• Additionally, Type III is described as a double ligament with two independent bands attaching to the intercondylar notch and the knee joint capsule.[2]

The ligamentum mucosum is present in approximately 64-66.7% of knee specimens examined in various studies.[1-2] Its biomechanical properties, such as tensile strength and stiffness, are significantly less than those of the primary stabilizers of the knee joint, suggesting it does not play a major role in knee kinematics but may be involved in anterior knee pain due to its connection with the infrapatellar fat pad.[1]