You have ruptured the anterior cruciate ligament in your knee, causing the knee to be unstable. The ACL controls the movement of the thighbone (femur) on the shinbone (tibia) which allows you to side step \ pivot when walking or running. It is unlikely to heal. However 10% of patients with a ruptured ACL can function almost normally in all activities including sports despite the torn ligament. However for many people, especially those active in sport or whose work depends on their knee to be stable, rupture of the ligament will lead to continual giving way and instability, and further damage to other arthritis protective structures, like the cartilage meniscus.