Runner’s Knee, otherwise known as patellofemoral pain syndrome, is characterized by pain around or behind the kneecap (patella). Symptoms can be triggered by repetitive motions such as running, walking, climbing stairs, squatting, or with static positioning such as kneeling and prolonged sitting. Your knee might also make a popping or grinding sound when bending. In addition, the pain can be diffuse and non-specific because it is not coming from an internal structure such as the meniscus or ACL. Runner’s Knee is a result of repetitive irritation of structures, so even non-runners can have symptoms of Runner’s Knee, much like non-tennis players can have Tennis Elbow.