Infrapatellar fat pad syndrome is characterized by injury or repetitive trauma to the adipose (fat) cushioning tissue deep to the patellar tendon and below the patella (kneecap) which results in impingement, entrapment or catching of the injured fat pad tissue between patella (kneecap) and the femur (thigh bone) or between the femur (thigh bone) and tibia (leg bone). The fat pad usually serves to protect the deep joint surfaces during kneeling and other direct pressure.
Frequent Signs and Symptoms
- Pain behind the patella, worsened by physical activity, including sports or when completely straightening the knee
- Swelling of the knee (occasionally)
- Tenderness and swelling (occasionally) on either side of the patellar tendon
Etiology (Causes)
Infrapatellar fat pad syndrome is caused by direct injury to the knee or repeated injury to the fat pad during activities that require maximal bending or straightening of the knee. The traumatized fat pad is altered and catches or pinches between the end of the femur and the upper part of the tibia or in the patellofemoral aspect of the joint.