The Infrapatellar Fat Pad in Osteoarthritis: From Pathophysiology to a Novel Therapeutic Target.

Osteoarthritis (OA) is a prevalent degenerative joint disease which affects millions of patients across the globe. The infrapatellar fat pad (IPFP) harbors diverse cell types with intricate intercellular interactions. Its mesenchymal stem cells (MSCs) and extracellular vesicles (EVs) possess significant biological functions and hold promising applications in regenerative medicine. IPFP exhibits active secretory capacity, releasing adipokines including leptin and adiponectin, along with various cytokines. Furthermore, it contains a rich neural network playing a crucial role in knee pain perception and sensation. Moreover, IPFP and synovium can be considered an integrated unit, exhibiting interactions both with each other and with cartilage. In imaging applications, IPFP is gaining widespread attention as an emerging biomarker. In clinical practice, the decision to resect or preserve IPFP remains a controversial topic. This article will review the latest research regarding the mechanism of IPFP in OA, and discuss its clinical applications, providing a theoretical basis for the prevention and treatment of OA.