Symptoms, causes, diagnosis and treatment

Pain and swelling in the knee can be caused by a number of conditions or injuries. In athletes, injuries to the posterolateral corner (PLC) of the knee is a common cause of this type of pain.

PLC is a group of anatomical structures that help support and stabilize the outer (lateral) region at the back of your knee. The main role of the PLC is to prevent the knee from rotating excessively or tilting (turning) outward (also known as varus).

This article will explain how PLC can be injured, the symptoms, the diagnostic process, and treatment options if this type of injury occurs.

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What is the posterolateral wedge (PLC)?

The posterolateral wedge (PLC) is made up of several different muscle tendons, ligaments, and joint tissues that support and stabilize the outside of the knee.

These structures are generally subdivided into primary and secondary stabilizers. The main group includes:

In addition, a group of secondary stabilizers also help to secure this knee area. This grouping includes:

The main role of the PLC is to prevent the knee from turning too far outwards. Additionally, bundling provides secondary assistance by preventing the bone in the lower leg (tibia) from moving forward or backward on the femur (femur).

Occasionally, one or more of the structures of the PLC may be trampled, strained or torn. Depending on the severity of the damage, it can cause significant pain and significantly affect your daily function.

How does an injury to PLC happen?

Sports injuries are responsible for a significant part of the problems with PLC. Typically, an injury occurs when there is a direct hit to the inner part of the front of the knee that causes the leg to flex outward.

A PLC injury can also be sustained without contact, for example if the knee hyperextends or moves away from the other leg in the varus position. Due to the way your knee usually moves during a posterolateral wedge injury, accompanying sprains or tears of the anterior cruciate ligament (ACL) or posterior cruciate ligament (PCL) are also very common.

PLC injuries can also be caused by several other situations. In particular, motor vehicle accidents and falls from high surfaces are frequently the cause. It should also be noted that when this type of trauma causes injury to the PLC, bone fractures in the leg are also common.

Symptoms of a PLC injury

Depending on the severity of your PLC injury, several different symptoms may be present. These include:

  • Severe pain, swelling, bruising and hardening of the knee and surrounding areas
  • Tilted outward position of the affected knee when standing
  • Difficulty walking or climbing stairs due to a feeling of instability
  • Numbness or tingling in the lower leg
  • Foot falling on the injured side

If you think you have suffered an injury to PLC or are experiencing any of the symptoms listed above, it is essential to be seen by an orthopedic specialist or emergency doctor. Your healthcare professional will be able to properly assess your leg and ensure that the correct treatment is started.

How a PLC injury is diagnosed

The diagnosis of a PLC injury begins with a comprehensive examination. In addition to looking for the symptoms mentioned above, your healthcare professional will usually move your legs in several different directions to assess for any instability. They may also perform the dial test, which involves lying on your stomach while a healthcare professional assesses your leg for lateral rotation to check for excessive movement.

In addition, imaging is frequently ordered to examine more precisely which anatomical structures are affected.

X-rays can be useful to rule out any concomitant fractures and to check for excessive laxity in this area of ​​the knee.

Magnetic resonance imaging (MRI) is also useful for visualizing the different tendons and ligaments of the PLC. This type of image helps your healthcare professional take a closer look at any sprains or tears that have occurred. MRIs may be less accurate in diagnosing PLC problems after 12 weeks, so they should be obtained as soon as possible if necessary.

Based on this assessment, your injury can be classified using the following system:

  • 1st year: 0 to 5 degrees of rotational or varus instability and an intact PCL
  • 2nd year: 6 to 10 degrees of rotational or varus instability and an intact PCL
  • 3rd year: 11 or more degrees of rotational or varus instability and rupture of the PCL

Treatment options for PLC injuries

The care you receive after a posterolateral wedge injury can vary widely depending on the structures involved and the overall severity. The sections below provide more details on the conservative and surgical treatment options available.

Non-operative treatment

Non-surgical treatment is generally reserved for isolated lesions of grade 1 or grade 2 PLC.

Depending on the structures affected, a stabilizer splint may be worn and crutches are often needed to temporarily relieve the strain on the knee.

Physiotherapy (PT) is also commonly prescribed. Your physiotherapist will focus on the following goals:

  • Wean yourself off your crutches and improve your walking pace
  • Regain your knee’s range of motion
  • Develop the strength and power of your leg muscles
  • Improved balance and stability of affected lower limbs
  • Reintroduce sport-specific movements like running, cutting and jumping, as appropriate

Operative treatment

People with grade 3 PLC lesions often respond poorly to non-operative treatment. They may also suffer from chronic knee instability or the development of long-term osteoarthritis if surgery is not performed. For this reason, operative treatment is generally recommended for injuries of this magnitude.

Typically, any damaged primary PLC stabilizers are surgically reconstructed using a graft (tissue) from another region of the body. In some cases, a transplant from a cadaver can also be used.

Surgical repairs can also be performed on any of the PLC’s secondary stabilizers to improve stability. Any other ligament injury (such as to the ACL or PCL) or accompanying fractures may also need to be treated.

After the procedure, you are often asked to immobilize your knee with a splint and not to put weight on the affected leg to protect the surgical area. This can last six weeks or more depending on your surgeon’s recommendations.

Physiotherapy is also usually started after your procedure. The goals of physiotherapy are often the same as when treating milder PLC injuries, although rehabilitation usually progresses at a slower pace. It may take six months or more of physiotherapy to resume sports or exercise after this type of surgery.


The posterolateral wedge (PLC) is made up of muscles, tendons, and ligaments at the back of the knee. Injury to the structures in this region, usually suffered during contact sports or a trauma such as a car accident, can cause significant pain and impair mobility. Treatment options will depend on the severity of the injury, but may include physical therapy to heal and strengthen PLC or reconstructive surgery.

A word from Verywell

Injuries to the posterolateral corner can cause significant pain and can have a dramatic impact on your ability to walk, work, or maintain your independence. Because of this, it can be a frustrating and scary problem to deal with.

To ensure that you can return to normal activities as quickly as possible, it is essential to have your injury assessed by a healthcare professional soon after an injury has occurred or you notice knee pain or pain. ‘other symptoms. Your health care provider can provide a diagnosis and describe the available treatment options. Be aware that while rehabilitation may take time, a full recovery is possible.