Posterolateral Corner

Posterolateral Corner Injury

Article by John Miller

What is a Posterolateral Corner Injury?

Injuries to the posterolateral corner of the knee (PLC for short) are most commonly associated with athletic traumas, motor vehicle accidents and falls. PLC injuries account for 16% of all knee ligament injuries and often occur in combination with other cruciate ligament injuries.

PLC provides both static and dynamic stabilisation to the knee joint. The static structures include the lateral collateral ligament (LCL or FCL), popliteus tendon, the popliteofibular ligament and the posterolateral capsule. Together these structures prevent varus collapse at the knee and external rotation of the tibia on the femur. Dynamic structures of the PLC play similar roles as the static structures but through movement. These structures include the popliteus muscle, iliotibial band, bicep femoris and the lateral gastroc tendon.

Your PLC is the outside of your knee that extends from the bottom of your femur (thigh bone) to the heads of your tibia & fibula (lower leg bones).

Ligaments and joint capsules surrounding the joint provide stability during movement and weight-bearing.

Importantly, the common peroneal nerve (a nerve that supplies the lower leg and toes) wraps around the top of the fibula. It can become compromised if there is an injury to the PLC of the knee.

What Causes a Posterolateral Corner Injury?

A combined hyperextension and varus force to the knee can injure the posterolateral corner of the knee. An example of this could be a blow to the inside of your knee with a straight knee.

Other mechanisms include coupled hyperextension and external rotation of the tibia or external rotation of the tibia and a large varus force.

What are the Symptoms of a Posterolateral Corner Injury?

Injuries affecting the PLC may or may not occur in conjunction with injuries to other structures in the knee. Symptoms of a PLC injury commonly include:

  • Pain or swelling over the posterolateral surface of the knee.
  • Pain is aggravated by weight-bearing activities, especially high loads going through the lower limb, such as walking up a hill, quick direction changes or jumping.
  • Feeling of weakness or ‘giving way’ around the knee.

If you have an injury to the PLC and the peroneal nerve is affected, you may also experience pins and needles or numbness in the lower leg and foot. You may also experience foot or ankle weakness.

How is a Posterolateral Corner Injury Diagnosed?

On examination, your physiotherapist or sports doctor will look for signs of a PLC injury. Palpation and a series of knee ligament stability tests on physical examination confirm or deny damage to the PLC. They will be graded accordingly based on severity. An MRI may be required to confirm the diagnosis.

What is the Treatment for a Posterolateral Corner Injury?


Most patients with a mild posterolateral injury start to recover within a few weeks of the damage with the appropriate rehabilitation.

Your physiotherapy treatment will aim to:

  1. Reduce pain and inflammation
  2. Normalise joint range of motion
  3. Strengthen the muscles of your lower limb
  4. Improve patellofemoral (knee cap) alignment
  5. Normalise your muscle lengths
  6. Improve your proprioception, agility and balance
  7. Improve your technique and function with walking, running, squatting, hopping and landing
  8. Minimise your chance of reinjury

We advise that you discuss your knee injury with a knee injury practitioner such as a sports physiotherapist, sports physician or knee surgeon. Twill provide you with the most accurate information regarding your specific injury and rehabilitation program.


Most grade I PLC injuries resolve entirely with conservative treatment. In severe cases, depending on the number of structures within the PLC involved, surgery may be required. Risks of surgery include infection, persistent instability and pain, stiffness, and difficulty returning to the previous activity level. Operations are determined case by case and severity of the injury.

Functional instability is a problem with PLC injuries. Your sports physiotherapist, sports doctor or knee surgeon should professionally guide your return to sport.

Post-Surgical Rehabilitation

Post-operative knee rehabilitation is one of the most important yet too often neglected aspects of knee surgery. The most successful and quickest outcomes result from the guidance and supervision of an experienced physiotherapist.

Your rehabilitation following knee surgery focuses on restoring full knee motion, strength, power and endurance. You will also require individualised balance, proprioception and agility retraining towards your specific sporting or functional needs.

Your physiotherapist has extensive knowledge in this field. We suggest you contact them for the best advice in your circumstances.

How to Prevent a Posterolateral Corner Injury?

There are several things you can do to reduce your risk of sustaining a PLC injury.

These include:

  • Correcting poor biomechanics of the knee or ankle joints
  • Adequate warm-up and stretching program before and after exercise
  • Correcting muscle imbalances in the lower limb
  • Adequate footwear during exercise
  • Avoid sudden increases in training frequency or intensity.
  • Strengthening muscles of the lower limb

Return to Sports with a Posterolateral Corner Injury

An inadequate rehabilitation regime often renders the athlete to experience difficulty when returning to their sport after sustaining a PLC injury. It is crucial to complete your specialised rehabilitation program as prescribed by your physiotherapist to enable a return to competition as quickly and safely as possible.

Common Causes - Knee Pain

Knee pain can have many origins from local injury, referred pain, biomechanical issues and systemic issues. While knee pain can appear simple to the untrained eye, a thorough assessment is often required to ascertain the origin of your symptoms. The good news is that once a definitive diagnosis is determined, most knee pain quickly resolves with the correct treatment and rehabilitation.

Knee Ligament Injuries

Knee Meniscus Injuries

Kneecap Pain

Knee Arthritis

Knee Tendon Injuries

Muscle Injuries

Knee Bursitis

Children’s Knee Conditions

Other Knee-Related Conditions

Knee Surgery

For specific information regarding your knee pain, please seek the assistance of a healthcare professional with a particular interest in knee condition, such as your physiotherapist.

Article by John Miller

ACL Tear Symptoms

An ACL (Anterior Cruciate Ligament) tear most often occurs during sporting activities when an athlete suddenly pivots, causing excessive rotational forces on the ligament.

Individuals who experience ACL tears describe a feeling of the joint giving out or buckling. You'll commonly hear a "pop."

Signs You May Have Sustained an ACL Tear:

  • Sudden giving way of the knee
  • Hearing a 'pop' at the time of injury
  • Sudden swelling of the knee joint
  • Pain in the knee when walking

How is an ACL Tear Diagnosed?

A well trained Sports Physiotherapist, Sports Physician or Orthopaedic Surgeon will generally be able to confirm the diagnosis of an ACL tear within the clinic and from your injury history.

An MRI scan can confirm your ACL tear and identify other knee injuries that may have occurred when your ACL was ruptured. These accessory injuries commonly include meniscal tears, bone bruising and collateral ligament injuries.

Confirmation of an ACL tear is essential since the treatment differs from a common knee ligament strain or a meniscus tear.

What to do if you have a Ruptured ACL?

Please be guided by your trusted healthcare practitioner for an ACL tear. Successful rehabilitation options vary depending on your age, activity level and extent of the injury. For specific advice, please consult an experienced knee physiotherapist, knee surgeon or sports doctor.

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Article by John Miller

Can You Live Life Without An ACL?

When an ACL injury occurs, the knee becomes less stable. The ACL injury is a problem because this instability can make sudden, pivoting movements difficult, and it may make the knee more prone to developing arthritis and cartilage tears.

If your knee is unstable, a common complaint of a sensation that the knee will 'give out' from under them. When this giving way sensation is because of an ACL injury, the knee joint is sliding too much. Joint sliding can be a problem because each episode of instability (the 'giving way' sensation) can cause damage to the knee cartilage. Therefore an ACL injury makes patients more prone to developing knee arthritis and meniscus tears.

Athletes often have particular difficulty once they have sustained an ACL injury. Many sports require a functioning ACL to perform common manoeuvres such as cutting, pivoting, and sudden turns. These high demand sports include, but are not limited to:

Patients may function in their normal daily activities without a normal ACL, but these high-demand sports may prove difficult. Therefore, athletes are often faced with the decision to undergo surgery to return to their previous level of competition.

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