Knee pain can be caused by several things from injuries to the knee, bone problems, cartilage problems and infections. They include arthritis, bursitis(inflammation from repeated pressure on the knee, like kneeling for a long time, overuse, or injury), dislocation of the kneecap, hip disorders, infection in the joints, knee injuries and tendinitis(pain in the front of your knee that gets worse when going up and down stairs).Other causes may include a torn cartilage, a torn ligament and strain or sprain.
Attribution: Straight Talk Foundation