Posterolateral Corner (PLC) Tears
What Is a Posterolateral Corner Injury?
The posterolateral corner of the knee is an important area that plays a pivotal role in stability. It includes three main structures:
- LCL (Lateral Collateral Ligament): Acts like a tight rope on the outside of the knee, keeping it from opening up.
- Popliteus Tendon: Helps prevent the shinbone (tibia) from rotating outwards.
- Popliteofibular Ligament: Works with the popliteus tendon to stop the tibia from rotating outwards.
Together, these structures stabilize the outside of your knee. Injuries to the PLC can make the outside of the knee gap open and increase the tibia’s outward rotation.
PLC injuries can occur in two main ways:
- Contact Injuries: Such as being hit on the inside of your leg during sports like football, soccer, martial arts or skiing or during car or motorcycle accidents.
- Non-Contact Injuries: Like falling on a knee that is hyperextended (bent backwards).
These injuries can affect a nearby nerve called the common peroneal nerve. Damage to this nerve can cause problems like “foot drop.” A foot drop is when you try to raise your foot or toes toward the sky, but it can’t. The foot stays in the position that you are in when you press on the accelerator in the car. Depending on the nerve damage, treatment might include:
- Ankle Foot Orthosis: A protective boot that helps stabilize the ankle.
- Nerve Decompression: To restore nerve function.
- Tendon Transfer: To help with walking if the nerve damage is permanent.
Symptoms of a PLC Injury
- Pain: Especially on the outer side of the knee.
- Swelling: The knee might swell up.
- Stiffness: The knee may feel stiff and hard to bend or straighten fully.
- Instability: You might feel like the knee is unstable or giving way, especially during side-to-side movements.
- Difficulty with Movement: It may be hard to stop or cut towards the affected side.
- Bruising: Discoloration and bruising on the outer side of the knee.
- Walking Problems: Walking can be painful or unstable, especially with severe injuries.
- Popping or Clicking: Some people feel a popping or clicking sensation when the injury occurs.
To diagnose a PLC injury, doctors use:
- Physical Examination: Testing your knee while it is straight and bent to find the injury’s location and severity. Also, stressing the knee with rotational exams to see if there is any restraint against the rotational stress.
- Varus Stress X-Ray: A special x-ray that helps measure how much the knee gaps open and diagnose the injury accurately. We compare this Xray to your uninjured knee.
- MRI: Provides detailed images of the knee to check the extent of the PLC injury and any other damage to ligaments, meniscus, or cartilage.
At a Glance
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