Posterolateral corner of the knee

Posterolateral corner of the knee

I’ve been treating a patient who had a nasty skiing injury and amongst other things had a complex injury to the posterolateral corner of the knee or PLC. Not so common as Meniscal (MCL) and Anterior Cruciate Ligament (ACL) damage.

What is the PLC?

The PLC is made up of of multiple ligaments and tendons around the knee. Tendon involve connective tissue that attaches muscle to bone, while ligaments connect one bone to another. The PLC is on the outside back (posterolateral) corner of the knee. There are many structures (28 separate components!) in the PLC.

These structures give stability to the back and outside of the knee where they prevent the knee collapsing outward (Varus strain), and the lower leg (tibia) rotating out (external rotation) on the thigh bone (femur).

PLC Injuries

These injuries usually occur with significant trauma and are combined with other knee injuries; usually ruptured Anterior and Posterior cruciate ligaments and Tibial Plateau fractures.

The main mechanism of injury is hyperextension – during hyperextension, the knee joint bends the wrong way, which often results in swelling, pain and tissue damage.

The structures involved are:

  • Lateral collateral ligament
  • Popliteus tendon
  • Popliteofibular ligament
  • Posterolateral capsule
  • Popliteal muscle
  • Iliotibial tract
  • Biceps Femoris muscle
  • Lateral Gastrocnemius head.



Treatment of grade 1 and 2 sprains can be managed conservatively with a hinged knee brace and weight bearing to pain for 4 weeks. Rehabilitation then involves reducing pain and swelling, normalising movement, strengthening of all muscles but especially the quadriceps as they assist the PLC in preventing hyperextension, and proprioceptive training.

The grade 3 sprains can sometimes be managed as above, depending on the lifestyle of the patient. However, some require repair, or if left for too long, reconstruction. Different surgeons use a range of lower limb structures for the reconstruction. Rehabilitation after this reconstruction is intense but usually successful.

Rehabilitation back into sport is the final stage of the programme, where the functional stresses and biomechanics of the specific sport are reproduced, and the knee strengthened to full fitness.

If you have any knee issues relating to sport, injury or wear and tear – why not book an appointment and we can work with you to achieve the goals you set?


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