Symptoms of an LCL Knee Injury

LCL, short for the lateral collateral ligament, is one of four ligaments of the knee joint. A thin, rope-like band, the LCL stretches from the outside of the femur (thigh bone) to the outside of the tibia (one of the bones of the lower leg). The function of the LCL is to hold and stabilize the knee on the lateral, or outside, part of the joint. LCL injuries can result from a blow to the knee, over-stretching, or tearing of the ligament.

Pain and Swelling

• The first sign of an LCL injury is often a loud pop or snapping sound that occurs at the moment of injury. This is followed by immediate, often severe, pain that is centered on the outer part of the knee. The tissue around the injury swells and is tender to the touch. In some cases, erythema--a redness of the skin resulting from the dilation of the capillaries--may manifest several days after the injury.

Knee Instability

• The tenderness and swelling may subside within a few days, but the joint may feel loose and unstable, a sensation CaringMedical.com has likened to "walking on roller skates." Some individuals with LCL injuries are able to predict when this looseness will occur; others live with uncertainty with every step they take. The knee may give out or suddenly lock up without warning. Some patients experience a feeling that there is a hitch, or catch, in the joint when walking.

Foot Weakness

• The peroneal nerve is a part of the sciatic nerve. Located on the lower, outside part of the knee, this nerve is responsible for sensations and movement in the foot and lower leg. In more severe LCL tears, the peroneal nerve may be stretched at the moment of injury, or it may be compressed due to the swelling in the surrounding tissues that follows. Either condition can cause weakness or numbness in the foot.

Ligament Laxity

• A ligament that is stretched or torn during injury may become lax, or loose, rendering it incapable of supporting the joint effectively. As detailed at Sportsinjuryclinic.net, LCL injuries are graded in severity according to the laxity of the ligament. Laxity is determined by applying force to stress the ligament and observing how the joint moves in response. In a grade-one injury, there is no laxity when stressed. Grade-two injuries present with some ligament laxity, but when the knee is stressed there is an endpoint, meaning the knee does not bend sideways. Grade-three injuries exhibit significant laxity.