Pain in the front portion of the knee can be caused by bursitis (inflammation of the lining of the joint, is possible due to injury or infection or autoimmune disease etc), arthritis, or
injury to the patella cartilage (front portion of the
knee). Pain on either sides of the
knee is usually related to meniscal tears, injuries to the collateral ligaments, and even to arthritis. Ligament injury causes pain to worsen on walking, bending and stretching the knee.