Infrapatellar fat pad

The infrapatellar fat pad (IFP; Hoffa's fat pad), is an intracapsular but extrasynovial structure located in the space between the inferior border of the patella, the femoral condyles, the tibial plateau, and the patellar tendon.[1-3]

Anatomically, the infrapatellar fat pad is composed of white adipose tissue organized into lobules, which are defined by thin connective septa. It is richly vascularized and innervated, containing a significant number of blood vessels and nerves.[4-5] The IFP attaches to several structures within the knee, including the inferior patellar pole, the femoral intercondylar notch via the ligamentum mucosum, the proximal patellar tendon, both menisci, and the anterior tibia via meniscotibial ligaments.[2]

The infrapatellar fat pad presents:

• A central body with a superior vertical cleft

• Two superior extensions: a lateral superior and a medial superior extension that wrap around the patella, which are visible on MRI and can be identified medially and laterally. These extensions and the dynamic nature of the IFP allow it to deform during knee motion, displacing superiorly and posteriorly during knee flexion.[2-3]

• A medial and a lateral extension

Histologically, the IFP consists of large adipose lobules near the patellar tendon and smaller lobules in the deeper portions, with the superficial lobules showing significant changes in size during knee flexion and extension.[3][5] This structural arrangement suggests a role in absorbing pressure variations and contributing to knee kinematics.[3][5]