
Patellofemoral pain syndrome occurs when the patella (kneecap) cartilage becomes overloaded due to overuse (often caused by high-impact activities) or as a result of poor alignment. High-impact sports (such as football, basketball, soccer, tennis and running) can aggravate existing abnormal kneecap alignment. In addition, running on uneven surfaces, like hills or trails, or playing on multiple surfaces (such as going from a grass to a hard court in tennis) also may increase the likelihood of patellofemoral pain.
The most common symptom of patellofemoral pain syndrome is a dull ache underneath the kneecap while walking down stairs, squatting or getting up after sitting for long periods of time.