Posterolateral corner injuries (PACE) are most often associated with

• Sports injuries
• Road traffic accidents
• Falls

The PACE provides stabilisation to the knee:

• Static (prevent varus collapse at the knee and external rotation of the tibia on the femur)
  • Lateral collateral ligament (LCL)
  • The popliteal tendon
  • The popliteofibular ligament
  • The posterolateral capsule. Together, these structures.

• Dynamic (similar roles to static structures, but through movement).
  • Popliteal muscle

PACE instability can be differentiated into

• Dorsal instability
  • Posterior cruciate ligament injury
• Lateral instability (varus)
  • Lateral collateral ligament (LCL) injury
• Rotational instability,
  • Injuries to the popliteal complex

Classification

• Type 1: Isolated posterior instability due to isolated PCL injury.
• Type 2: posterolateral rotational instability without lateral instability (PCL + popliteal complex)
• Type 3: posterolateral rotational instability with varus instability (PCL + popliteal complex + partial LCL)
• Type 4: posterolateral rotational instability with varus instability (PCL + popliteal complex + total LCL)

What causes an PACE injury?

• Combined hyperextension trauma and varus force to the 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 an PACE injury?

• Injuries to the LPC may or may not occur in conjunction with injuries to other knee structures.

• Pain or swelling of the posterolateral surface of the knee.
• Pain that is aggravated by weight-bearing activities, particularly those involving high loads passing through the lower limb such as hill climbing, rapid changes of direction or jumping
• Feeling weak or ‘giving way’ around the knee.
• If you have an LPC injury and the peroneal nerve is affected, you may also feel or numbness in the leg and foot.
• You may also feel weakness in the foot or ankle.
• Outward bending of the affected knee while standing.
• Difficulty walking or climbing stairs due to a feeling of instability.
• Numbness or tingling in the lower leg.
• Feet that fall on the injured side