Patellofemoral pain syndrome is a condition in which pain is felt under the kneecap. The patella is the bone that makes up the kneecap. The femur is the thigh bone. This bone forms the upper part of the knee. In people with patellofemoral pain syndrome, the patella rubs painfully against the femur.

This pain occurs during exercise or movement. It is most common during weight bearing activities such as running.

The Kneecap
Copyright © Nucleus Medical Media, Inc.

The pain is the result of inflammation of soft tissues around the kneecap. It can be due to a number of different factors or conditions, such as overuse and improper use of the legs.