(Albert Hoffa, 18591907, German surgeon), a condition characterized by traumatic and inflammatory changes occurring in the infrapatellar fat pad in young athletes, which may lead to pain, swelling and restricted motion of the knee. Hypertrophy of the fad pad may cause it to become entrapped between the tibia and femur when the flexed knee is extended suddenly. Eventually fibrosis may ensue. On MR images acute findings indicate the presence of fluid and chronic findings resemble those of scarring after knee arthroscopy. In some patients, rupture of the overlying synovial fold and haemarthrosis may occur after an injury to the infrapatellar fat pad. (See fat pad (III:1), Fig. 1, fat pad (III:1), Fig. 2)