The infrapatellar fat pad (Hoffa's fat pad) is a cylindrical piece of

fat In nutrition science, nutrition, biology, and chemistry, fat usually means any ester of fatty acids, or a mixture of such chemical compound, compounds, most commonly those that occur in living beings or in food. The term often refers spec ...

that is situated under and behind the

patella The patella, also known as the kneecap, is a flat, rounded triangular bone which articulates with the femur (thigh bone) and covers and protects the anterior articular surface of the knee joint. The patella is found in many tetrapods, such as m ...

bone within the

knee In humans and other primates, the knee joins the thigh with the leg and consists of two joints: one between the femur and tibia (tibiofemoral joint), and one between the femur and patella (patellofemoral joint). It is the largest joint in the hu ...

Clinical significance

The fat pad is a normal structure but it can sometimes become a problem: * It can become damaged and painful * It can be deliberately removed at

arthroscopic surgery Arthroscopy (also called arthroscopic or keyhole surgery) is a minimally invasive surgical procedure on a joint in which an examination and sometimes treatment of damage is performed using an arthroscope, an endoscope that is inserted into the jo ...

to make it easier for the surgeon to see what they are doing - but this can also lead to scarring and pain. * It can become hypertrophic and may become impinged between the patella and the femoral condyle, causing sharp pain when the leg is extended. This is called infrapatellar fat pad syndrome or Hoffa syndrome. * It can become involved in the process of

arthrofibrosis Arthrofibrosis (from Greek: ''arthro-'' joint, ''fibrosis'' – scar tissue formation) has been described in most joints like knee, hip, ankle, foot joints, shoulder (frozen shoulder, adhesive capsulitis), elbow (stiff elbow), wrist, hand joints as ...

and become scarred (fibrotic) and contracted, pulling the patella down into an abnormally low position.

References

{{Authority control Joints