The infrapatellar plica is a filmy structure - not always present - that stretches from the notch of the femur to the fat pad. It is also commonly referred to as the ligamentum mucosum.
What use is the infrapatellar plica?
This structure is not present in every knee. It is also frequently removed to improve access during keyhole surgery of the knee, without apparent ill effect.
Arthroscopic Untethering of the Fat Pad of the Knee: Release or Resection of the Infrapatellar Plica (Ligamentum Mucosum) and Related Structures for Anterior Knee Pain. Smallman TV, Portner OT, Race A, Shekitka K and Mann K. Arthrosc Tech. 2018 May; 7(5): e575–e588.
MR Imaging of Infrapatellar Plica Injury. Cothran RL et al. American Journal of Roentgenology. 2003;180: 1443-1447. 10.2214/ajr.180.5.1801443.