The common causes of knee
pain are injury, degeneration, arthritis, infection, and rarely bone tumors. Athletic injuries and trauma are few risk factors for knee pain. Ligament injuries, meniscal tears, runner’s knee, tendinitis and fractures are common causes of knee pain. Osgood Schlatter disease is a condition seen in teenage boys and girls which causes a painful bump below the knee. It's usually caused by overuse and irritation of the tendon. The pain comes and goes.