Pain through the front of the knee is common with a number of diagnoses
A common cause of anterior knee pain is irritation of the back of the knee cap. Known as patellofomoral syndrome, daily irritations may include deep squatting, climbing up and/or down stairs and sitting with knees bent for a prolonged period of time. Patellofomoral syndrome can be as a result of overuse, repetitive knee injuries, lack of strength, too much flexibility and/or posture (back, hips, feet).
Considering the large amount of causative factors and how they all interact to produce anterior knee pain, a full thorough physiotherapy assessment is highly recommended.