Patellofemoral pain syndrome is the medical term for pain around the front of the knee that is not associated with any signs of damage or problems in the knee. Typically, the pain is worse when walking up or down stairs.
There may also be swelling around the kneecap and a grating sensation when the knee is bent or straightened.
It is common in people who play sports. Treatment is with rest, pain relievers, and physical therapy. It make take several months to recover fully, and sometimes the condition persists for years.