What is infrapatellar plica and how is it classified?

Updated: Apr 20, 2020
  • Author: Tracy Lee Bigelow, DO; Chief Editor: Thomas M DeBerardino, MD  more...
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The plica that is the least symptomatic of all, the infrapatellar plica (ligamentum mucosum) is, ironically, the one most commonly encountered. Some authors even claim that the infrapatellar plica is never responsible for plica syndrome. This bell-shaped remnant originates in the intercondylar notch, widens as it sweeps through the anterior joint space, and attaches to the infrapatellar fat pad. This plica's ability to obscure portal entry sites or interfere with visualization during arthroscopy is touted as its only significance.

Kim et al classified ligamentum mucosum (ie, infrapatellar plica) into the following five groups [13] :

  • Separate type - 60.5%
  • Split type - 13.5%
  • Vertical septum type - 10.5%
  • Fenestra type - 1.0%
  • None present - 14.5%

In a clinical study of 400 knees in more than 350 patients, Kim and Choe found suprapatellar plicae in 87%, mediopatellar plicae in 72%, infrapatellar plicae in 86%, and lateral plicae in 1.3%. [14]

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