Multi-Ligament Knee Tears

A knee dislocation is the term used to describe a multi-ligament injury that involves injury to at least two ligaments of the knee. This is a serious condition because the knee is very unstable and can result in severe damage to blood vessels and nerves. These injuries can potentially be life- and limb-threatening, and, therefore, these injuries are medical emergencies.

There are two primary types of knee dislocations: low-energy and high-energy dislocations (motor vehicle crash, fall from height, etc.). If a knee dislocation occurs during a sporting event, it is critical to reduce the knee back to its normal position (putting the ends of the bones back in alignment). When a knee dislocation happens, regardless of whether it is a low- or high-energy type, other structures, including the skin and other soft tissues, such as the muscles, tendons, nerves, and blood vessels, can be severely damaged.

With a possible knee dislocation, you should go to the emergency room immediately. Doctors will assess the skin and soft tissues, pulses, and nerve function. The popliteal artery is the main blood vessel to the lower leg and runs behind the knee. In a knee dislocation, the popliteal artery can be injured, affecting the blood supply to the lower leg. If there is any concern about an artery injury, your doctor will request a CT angiogram, where dye is injected into the artery, to assess for vessel injury.

Assuming there is no artery or nerve injury and the joint is reduced (put back in place), your doctor will assess whether the joint is stable after it is reduced or is still slipping out of place. If it is still slipping, a brace or an external fixator, where pins are placed into the bones to hold them with metal bars, may be necessary to hold it in place. An MRI scan should be obtained to examine the cartilage, ligaments, and menisci status.

Whenever possible, surgery within the first few weeks after a knee dislocation is recommended to stabilize the knee if satisfactory range of motion has been achieved. Attempting to operate on a stiff knee can jeopardize the outcomes of the procedure. In patients who may have an open fracture (bone through the skin), who have severe diabetes or kidney problems, or who are elderly, this may not always be possible. However, surgery would be indicated in healthy patients with an acceptable range of motion who do not have any lacerations or problems around the area of the knee dislocation.

A detailed history, comprehensive physical examination, special X-rays, and magnetic resonance imaging are key for a successful diagnosis. Knee surgeon, Dr. Daniel Kaplan, may order stress X-rays to determine the severity of the injury. These special X-rays allow Dr. Kaplan to objectively quantify and diagnose (based on validated systems) which ligaments are involved with millimeter accuracy.