Posterolateral Corner Injury

What Is A Posterior Lateral Corner (PLC) Injury

The posterolateral corner is a group of ligaments, tendons, and muscles located at the back and outer side of the knee. These structures are essential for keeping your knee stable during activities like walking, running, or jumping. They prevent the shin bone (tibia) from twisting outward or shifting backward.

A PLC injury happens when one or more of these structures is stretched, torn, or damaged. This can occur from a strong force, such as a sports collision, a fall, or a car accident that hits the inside of your knee or forces your leg to twist outward.

PLC injuries often happen alongside other knee injuries, such as tears of the anterior cruciate ligament (ACL) or posterior cruciate ligament (PCL). Studies show that 16% to 28% of people with major knee ligament injuries also have a PLC injury. When more than one part of your knee is hurt, the joint can become significantly unstable.^[1]

PCL injuries can lead to pain, swelling, or a feeling that your knee could “give out.” Simple actions, like walking, climbing stairs, or getting up from a chair, may become difficult or unsafe. Ignoring the injury can lead to long-term joint weakness and ongoing pain, limiting your ability to stay active or return to sports.

Common Causes And Contributing Risk Factors

Certain forceful movements and incidents can damage the posterolateral corner. Some causes are sudden and traumatic, while others develop over time. High incidence of these injuries occurs in athletes playing sports such as Jujitsu and soccer. Understanding these risks can help you protect your knee and know what to avoid.^[2]

Landing Hard On A Bent Knee

Landing from a jump or fall with your knee bent places intense force on the outer structures of your knee. The posterolateral ligaments are suddenly compressed and stretched, which can cause them to tear. This is common in high-impact sports like basketball or gymnastics, where unplanned landings are frequent.

Knee Overextension During Movement

When you stretch your knee too far, such as during a misstep or a sudden stop, the joint can hyperextend. This forces the PLC ligaments to extend past their normal limit, increasing the risk of sprains or tears. Overextension is often seen in football or contact sports that involve rapid leg movements.

Blunt Impact To The Front Of The Knee

A strong blow to the front of your knee, often from falling on a hard surface or during car accidents, can push the tibia (shin bone) backward. This backward force can strain or tear the PCL structures.

Sharp Twisting

Quick, twisting actions, like pivoting suddenly or planting your foot while turning, place the PLC under undue stress. This is because, during these motions, the structural part of the PLC attempts to resist unnatural or excessive rotation. If the pressure is too high, these tissues can tear. Sharp twisting injuries of the PLC are commonly seen in skiing.

Dislocated Joint

A knee dislocation happens when the bones of the knee joint—the thigh bone, shin bone, and kneecap—are forced out of their normal positions. This injury often damages several other nearby structures, including the PCL ligaments, blood vessels, or nerves. Knee dislocation usually results from major trauma, such as a car accident or a hard fall.

Repeated Strain

Consistent stress from overuse, poor movement mechanics, or repetitive kneeling can cause microtears and damage to PLC tissues, weakening them. Over months or years, this repeated strain makes the knee more likely to develop a significant injury, especially if the tissues are not given time to recover.

How To Spot The Signs Of A PLC Injury

Recognizing PLC injuries early is key to avoiding long-term problems. Symptoms can range from mild to severe and often develop soon after the injury. Pay attention if you notice these signs, especially following a fall, twist, or direct hit to your knee:

• Bruising: Bruising refers to skin discoloration from bleeding under the skin, often caused by trauma. Read more about Bruising.
• Knee Locking Up: Knee locking up is a sudden inability to move the knee, commonly linked to meniscus issues. Read more about Knee Locking Up.
• Outside of Knee Pain: Outside of knee pain refers to discomfort along the lateral knee, often caused by IT band issues.
• Outside of Knee Swelling: Outside of knee swelling refers to fluid buildup on the outer knee, usually caused by injury.
• Pain Behind Knee: Pain behind the knee refers to discomfort in the back of the joint, often caused by a cyst or strain.
• Side-Of-Knee Pain: Side-of-knee pain refers to discomfort on either side of the knee, often caused by ligament or cartilage issues.
• Knee Instability: Knee instability is a feeling of the knee giving out, often caused by ligament damage.
• Limited Range Of Motion: Limited range of motion is reduced joint movement, often caused by stiffness or injury. Read more about Limited Range Of Motion.
• Tenderness: Tenderness is pain when touching an area, often due to injury or inflammation. Read more about Tenderness.
• Popping Sound: A popping sound refers to a snapping noise from a joint, often harmless or caused by ligament movement. Read more about Popping Sound.

Expert Diagnosis For The Cause Of A Torn PLC

PLC injuries can be complex and involve multiple knee components. Accurate diagnosis is essential to guide treatment decisions. Diagnostic tools include:

• Clinical Evaluation: Your physician will ask about the injury, your symptoms, and your medical history. A careful physical exam can be used to check for swelling, bruising, or restricted movement.
• Physical Tests: Special stress tests, such as the dial test or external rotation test, help identify if the PLC and other ligaments are unstable or unable to move as they should. These tests measure the knee’s ability to resist twisting or sideways force.
• Imaging Techniques: Imaging tests provide clear images of the inner aspect of the knee. X-rays can help identify bone injuries or joint changes, while Magnetic Resonance Imaging (MRI) provides pictures of ligaments or tissues to diagnose tears and inflammation. Advanced techniques like stress X-rays or ultrasound look at the knee in motion to understand how different structures interact with one another.

How Early Support Leads to Better Health Outcomes

Seeking medical attention soon after a knee injury or when experiencing ongoing pain without a clear cause is important. Early diagnosis helps prevent further damage, reducing the risk of long-term complications, such as ongoing instability or joint degeneration.

Pain medication may play a role in the treatment journey, as it helps ease flare-ups and makes it easier for you to adhere to the care approaches developed with your physician. However, relying solely on medications can mask the root of the problem and let an underlying condition go untreated. They also come with side effects, including reliance and increased risk of stomach ulcers, stroke, heart attack, and addiction.

Understanding your injury and acting early allows you to make informed decisions, avoid long-term problems, and protect your knee’s health and function.

What Are The Treatment Options For PLC Injuries?

Treating PLC injuries involves multimodal approaches that make symptoms more manageable while addressing the root cause of pain. Options include:

• NSAIDs Treatment: NSAIDs (nonsteroidal anti-inflammatory drugs) are medications commonly used to manage inflammation and discomfort in muscles and joints. Read more about NSAIDs Treatment.
• Physical Therapy Treatment: Physical therapy is a structured approach using guided movement and rehabilitation techniques that may help support joint function and mobility. Read more about Physical Therapy Treatment.
• PRP Injections for Knee: PRP injections use a patient’s own platelet-rich plasma and may help support tissue function in joints, tendons, or ligaments. Read more about PRP Injections for Knee.
• Steroid Injections Treatment: Steroid injections are anti-inflammatory shots that may help manage swelling and discomfort in joints or the spine. Read more about Steroid Injections Treatment.
• RICE Method: Rest, Ice, Compression, and Elevation help reduce swelling, relieve pain, and support early-stage recovery following knee injuries.
• Knee Brace: A knee brace provides stability and support to reduce strain, protect the joint, and aid in healing during daily movement or physical activity.
• PCL Reconstruction: The torn PCL is replaced with a graft from the patient or a donor. This restores knee stability and is commonly used for complete or chronic tears.
• PCL Repair with Internal Brace: The existing ligament is sutured and supported with a synthetic internal brace. This technique is ideal for fresh tears with good tissue quality.