Ligamentum mucosum

The ligamentum mucosum, also known as the infrapatellar plica, is an embryological remnant of a synovial septum and one of the types of knee plicae

It is the most common knee plica, with incidence ranging from 65% 4 to 85.5% 5 of the population.

The classification according to the plica morphology was proposed by Kim 4.

  • separate type - completely separated from the ACL (60.5%)
  • split type - longitudinally divided (13.5%)
  • vertical septum type - attached to the ACL (10.5%)
  • fenestra type - with fenestrated vertical septum (1.0%)

It is best seen on T2/PD sagittal images as a curvilinear, low signal structure, originating from the anterior intercondylar notch and traversing the infrapatellar (Hoffa's) fat pad to attach to the inferior pole of the patella. It may connect to the anterior cruciate ligament (ACL). Its thickness ranges from very thin to almost as thick as the anterior cruciate ligament.

Anatomy: Lower limb

Anatomy: Lower limb

Article information

rID: 38879
Section: Anatomy
Synonyms or Alternate Spellings:
  • Infrapatellar plica

Support Radiopaedia and see fewer ads

Cases and figures

  • Case 1: ligamentum mucosum injury
    Drag here to reorder.
  • Case 2: normal
    Drag here to reorder.
  • Updating… Please wait.

     Unable to process the form. Check for errors and try again.

     Thank you for updating your details.