The location of the knee pain can be a useful guide to the cause of
pain.
Pain on the outer side 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. Meniscii too if torn or injured, result in joint instability—that is you are not confident the knee joint will take your weight. Often the person feels a popping sensation on moving the joint.