Knee Ligament Injury Symptoms

Ligaments are tough bands of connective tissue that bind bones to each other and stabilize joints. In the knee, four major ligaments bind the thighbone, or femur, to the shinbone, or tibia. These ligaments are called the anterior cruciate, the posterior cruciate, the lateral collateral and the medial collateral ligaments.

The knee is the largest joint in the body and also the most vulnerable to injury in athletes. Any of the knee ligaments can become stretched or torn due to trauma.


Because the ligaments hold the bones of the knee in place, tearing or stretching a ligament can disrupt the structural integrity of the joint. The cruciate ligaments prevent forward and backward dislocation of the knee bones. The collateral ligaments prevent the knee bones from sliding to the lateral or medial side. A sudden, hard blow to the knee from an outside source, such as a collision with another player during team athletics, can result in a ligament tear corresponding with the direction from which the force was applied.

Ligament injuries, also referred to as sprains, are classified by a grading system that rates them from Grade 1 to Grade 3, according to the level of severity. Grade 1 ligament injuries, in which the ligament is stretched but not torn, cause no overall instability. Grade 2 sprains, which occur when the ligament is partially torn, are mildly unstable. Grade 3 sprains are the result of complete tearing of the ligament, and they demonstrate clear instability, according to the British Health organization, Bupa.

Instability is often described by the patient as a feeling of the knee “giving way,” according to the Mayo Clinic.


Tearing of the soft tissue of the knee causes an inflammatory response, which draws fluid to the area and causes swelling, a condition called edema. Swelling is more immediate and prominent in injuries to the anterior and posterior cruciate ligament, which occur when a force collides with the front of the knee, driving it backward. Injuries to the collateral ligaments cause less severe swelling. In each of these cases, the swelling may be localized to the area of the ruptured ligament.


Ruptures of the knee ligaments can cause immediate, and significant, pain that worsens upon movement. The degree of pain is proportional to the degree of injury and may manifest as tenderness directly over the area of the damaged ligament.

Difficulty Walking

Patients’ mobility is hindered due to the cumulative effects of the other symptoms. Instability prevents the joint from supporting the weight of the body. Joint movement may be hindered by the accumulation of fluid in the injured area. The pain involved in a knee injury is often severe enough to deter movement.

About this Author

For 15 years, Christina Ray’s award-winning work has appeared in film, television, newspapers, magazines and the Internet. She has worked as a story editor on the CBS drama Flashpoint, and her column, “Road Stories,” appears bimonthly in The Driver Magazine. She has a B.S. in biology, and a Doctorate in Chiropractic from Palmer College.