LCL & PLC Injuries

Anatomy

Static Stabilizers

• LCL
• Popliteus tendon
• Arcuate ligaments
• Capsule

Dynamic Stabilizers

• Biceps femoris
• Popliteus muscle
• ITB (Iliotibial band)
• Lateral head of gastrocnemius

Popliteus Tendon

• Intra-articular at the popliteal hiatus of the lateral meniscus.
• Important stabilizer of the lateral meniscus via popliteomeniscal ligaments.

Arcuate Complex

• Y-shaped ligamentous complex attaching to the fibula head.

Layered Structure

Capsule

• Gives rise to meniscotibial and meniscofemoral ligaments.
• Meniscotibial ligaments are associated with Segond fracture.
• Meniscofemoral ligaments include Humphrey’s and Wrisberg’s ligaments.

LCL (Lateral Collateral Ligament)

• Shape: Tubular.
• Origin: Lateral epicondyle of femur to fibula head.
• Blood Supply: Superolateral and inferolateral geniculates.
• Biomechanics:
  • Primary restraint to varus at 5° and 25° knee flexion.
  • Primary restraint to external rotation (ER).
  • Popliteus restricts posterior tibial translation, external rotation, and varus.

Injury Mechanism and Symptoms

• Varus and anterior-posterior (AP) stress to the knee, especially in extension.
• Instability with knee extended.
• Symptoms: Lateral pain, difficulty with stairs, unable to pivot on the knee.

Examination

Varus Instability

• At 30° flexion: Indicates isolated LCL injury.
• At 0° and 30° flexion: Suggests LCL and PCL or ACL involvement.

Dial Test

• Test for PLC injury.
• At 30° and 90° flexion: Positive if external rotation (ER) >10°.
  • Positive at 30° only indicates PLC.
  • Positive at both 30° and 90° indicates PCL involvement as well.

Reverse Pivot Shift

• Extend the knee from a flexed position in external rotation (ER).
• Feel for knee relocation.

External Recurvatum Test

• Lift legs by big toes.
• Look for ER and sag of tibia.

Posterolateral Drawer Test

• At 30° and 90° flexion:
  • 30°: Positive indicates PLC.
  • 90°: Positive indicates PCL.

Classification of PLC Injury

• Grade 1: Minimal damage, varus opening of the joint line.
• Grade 2: Partial damage, <10mm opening.
• Grade 3: Complete disruption, >10mm opening.

Management

Non-Operative Management

• For grade 1 and 2 injuries.
• ROM and quadriceps exercises with proprioceptive training.

Operative Management

• Avulsed LCL.
• Isolated unstable symptomatic grade 3 PLC (involving LCL and other PLC structures).
• Combined injuries with PCL or ACL (more common).

Surgical Principles

• Best results for PLC and LCL injuries with acute repair within 2-3 weeks.
• After 2-3 weeks, scar tissue makes primary repair outcomes worse.
• Acute setting: Use suture anchors for repair; direct repair can be done open.
• Arthroscopy is used to screen for and treat intra-articular injuries.

Chronic PLC and LCL Instability

• Use synthetic grafts (LARS) for LCL via drill holes.
• Anatomic repair with Y-shaped Achilles allograft.
• Often in combination with PCL or ACL reconstruction.
• Concurrent treatment for PCL and ACL.
• If patient has a pre-existing varus deformity, consider high tibial osteotomy (HTO) to correct the axis.
• Common peroneal nerve should be identified below the biceps femoris at the fibula head and traced proximally.
• Consider extension splinting post-op for 4 weeks to prevent external rotation of the tibia.