A multi-ligament knee injury is the injury of two or more ligaments in the knee.
The knee has two cruciate ligaments in the center of the knee joint that control the front-to-back motion of the knee. The ligament in the front of the knee is called the anterior cruciate ligament (ACL) and the ligament in the back is called the posterior cruciate ligament (PCL). The ligaments on the sides of the knee are called collateral ligaments. The collateral ligaments stabilize the knee during side-to-side motion. The ligament on the inside is called the medial collateral ligament (MCL) and the ligament on the outside is called the lateral collateral ligament (LCL).
Additionally, there are other ligaments and tendons on the inner and outer aspects of the knee that control the rotation of the tibia (shin bone). These ligaments include the posterior oblique ligament (POL) on the inside, and the popliteus tendon and popliteofibular ligament on the outside.
There is also an important ligament on the back of the knee called the oblique posterior ligament which prevents the tibia from bending in the opposite direction (recurvatum).
A knee dislocation is the term used to describe a multi-ligament injury that involves both cruciate ligaments (ACL and PCL). 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 basically two types of knee dislocations: sports related and high energy dislocations (motor vehicle crash, fall, 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 after a high-velocity impact, such as a motor vehicle accident or a fall from a significant height, this can be a more serious injury, because the skin and other soft tissues such as the muscles, tendons, nerves, and blood vessels can be severely damaged.
Symptoms depend on the severity of the injury and the number of anatomical structures involved. Below are some of the most common symptoms of a multi-ligament knee injury:
Pain: Diffuse knee pain. The pain may range from mild to severe, depending on the extent of the injury.
Swelling
Stiffness: The knee may become stiff, making it difficult to fully bend or straighten the leg.
Instability: An individual with a torn ligament may feel that the knee is unstable, as if it’s “giving way” or unable to support their weight properly.
Bruising: Bruising can develop around the site of the ligamentous injuries, and the discoloration is often seen on the inner side of the knee.
Difficulty Walking: Walking may be uncomfortable or painful, particularly if the multi-ligament injury is severe.
Popping or Clicking Sensation: Some people report a popping or clicking sensation when the injury occurs, which may be followed by pain and swelling.
With a possible knee dislocation, you should go to the emergency room immediately so that you can get a close and thorough assessment of the skin and surrounding muscles, pulses, and the overall status of the popliteal artery.
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 entire 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), Dr. Chahla will assess in the office whether the joint is stable after it is reduced, or if it is still slipping out of place. If it is still slipping, a cast or brace may be necessary to hold it in place. If it is stable to reduction, then a thorough physical examination will be performed to assess range of motion and integrity of ligamentous stability. Dr. Chahla will then order an MRI scan to look at the status of the cartilage surfaces, ligaments, and menisci. Finally, a special set of x-rays, called stress x-rays, will likely be obtained. These special stress x-rays allow Dr. Chahla to objectively quantify and diagnose (based on validated systems) the exact extent of a posteromedial corner, posterolateral corner injury , or PCL injury with millimeter accuracy.
At a Glance
Dr. Jorge Chahla
Triple fellowship-trained sports medicine surgeon
Performs over 700 surgeries per year
Assistant professor of orthopedic surgery at Rush University
