How do collateral ligament injuries cause problems?
An injury violent enough to actually tear one of the collateral ligaments causes significant damage to the soft tissues around the knee. There is usually bleeding and swelling into the tissues surrounding the knee. The damage may also cause bleeding into the knee joint itself. The knee becomes stiff and painful especially when putting weight on that leg. As the initial stiffness and pain subside the knee joint may feel unstable, and the knee may give way and not support your body weight. Chronic, or long-term, instability due to an old injury to the collateral ligaments is a common problem. If the torn ligament heals but is not tight enough to support the knee, a feeling of instability will continue to be felt. The knee will give way at times and may be painful with heavy use.