The infrapatellar pad, a fibro-adipose tissue, is gaining wide attention in the field of rheumatological research. As an extrasynovial tissue, the infrapatellar fat pad does not directly interact with the articular cartilage; based on its location in close contact with the synovial membrane, and due to the metabolic properties of adipose tissue, it may influence the behavior of the synovial membrane. In fact, considering evidence of macroscopic and microscopic anatomy, the infrapatellar fat pad is the site of insertion of the infrapatellar and medial synovial plicae. The infrapatellar fat pad and the synovial membrane may be considered a morpho-functional unit.
Macchi et al. (2018) summarize in their review article The infrapatellar fat pad and the synovial membrane: an anatomo-functional unit, most recent published evidence on the anatomic, physiologic and biomechanical inter-relationship between the infrapatellar fat pad and the knee synovial membrane. A very detailed and interesting article!