PLC Tear

The posterolateral corner (PLC) of the knee is a complex structural region that provides stability and resists excessive rotational and varus forces. Varus forces refers to an inward pressure or force applied to the knee, causing it to bend outward in an unnatural way. Imagine standing with your feet on the ground and someone pushing the inside of your knee outward. This type of force can stress the outer structures of the knee, including the lateral collateral ligament (LCL) and other parts of the posterolateral corner (PLC), increasing the risk of injury. It is often seen in high-impact sports, falls, or accidents where the knee is forced into an awkward position.

The PCL consists of several key structures that work together to maintain knee function and protect against excessive stress. These structures include:

• Lateral collateral ligament (LCL) – the primary knee stabilizer along with the Popliteus tendon and the Popliteofibular ligament
• Lateral capsule thickening
• Iliotibial band
• Biceps femoris tendon
• Lateral gastrocnemius tendon
• Fibular collateral ligament
• Arcuate ligament
• Posterolateral capsule

These structures work together to stabilize the knee during dynamic movements and protect it from excessive stress, particularly in high-impact activities such as running, jumping, and sudden changes in direction. The PLC also plays a critical role in maintaining proper biomechanics, ensuring smooth articulation of the knee joint during weight-bearing activities. A posterolateral corner (PLC) injury is a serious knee injury that can cause instability on the outer side of the knee. It often occurs alongside other ligament injuries.

PLC injuries are traumatic knee injuries usually caused by high-impact trauma or sudden twisting motions. They commonly occur in sports like football, soccer, and basketball, where players frequently change direction or experience contact injuries. A direct hit to the inner front part of the knee, overextension of the knee, or a severe force pushing the knee outward can all lead to PLC damage. They usually occur with an ACL ligament injury.

Beyond sports, car accidents are another common cause, where the knee can be injured by hitting the dashboard or from the force of a sudden stop. Additionally, falls from heights or work-related injuries in physically demanding jobs can put stress on the knee, increasing the risk of a PLC injury. Since PLC injuries often happen with other knee ligament tears, they can be difficult to diagnose and may require specialized care to restore knee stability and function.PCL injuries are classified into three grades based on severity:

• Grade 1 (Mild) – The PCL is stretched or partially torn but remains stable. Symptoms include mild swelling and discomfort.
• Grade 2 (Moderate) – A more significant PCL tear causes some instability, with the knee feeling like it “gives out.”
• Grade 3 (Severe) – A complete PCL tear results in major instability, often with other ligament injuries.

• Pain and swelling on the outer side of the knee
• Instability or a sensation of the knee giving way
• Difficulty walking, especially on uneven surfaces
• Decreased range of motion, particularly in knee extension
• Numbness or tingling due to potential peroneal nerve involvement
• Bruising and tenderness along the posterolateral knee
• Weakness in foot dorsiflexion if the common peroneal nerve is affected
• Audible popping or snapping sounds at the time of injury
• Difficulty with pivoting or twisting movements

• Clinical Examination: A thorough physical examination assesses ligament stability, swelling, and range of motion. Dr. Gazzaniga will use special tests to evaluate PLC integrity.
• Patient History: A detailed history of how the injury occured provides essential clues for diagnosis. Patients often report an acute twisting injury, hyperextension, or direct trauma.
• X-rays: Standard knee X-rays can help identify fractures, joint space narrowing, or tibial plateau injuries, which may accompany PLC injuries.
• Stress Radiographs: These images assess knee stability by applying controlled varus stress during X-ray imaging.
• MRI: An MRI provides a detailed view of soft tissue structures, including ligaments and tendons, helping confirm PLC damage and identify associated injuries.
• Ultrasound: Dynamic ultrasound can be useful in evaluating ligament integrity and detecting any abnormal movement or gaps in the ligamentous structures.
• Computed Tomography (CT) Scan: In cases of complex injuries involving bone fractures, a CT scan may provide additional detail to assist in treatment planning.

Early diagnosis of PLC injuries is crucial to prevent long-term instability, chronic pain, and degenerative joint changes. If left untreated, these injuries can lead to progressive knee dysfunction and an increased risk of osteoarthritis. Prompt medical evaluation and an accurate assessment of the injury severity allow for appropriate treatment strategies, whether through conservative management or surgical intervention. Recognizing the signs and symptoms early ensures optimal recovery and a return to an active lifestyle.