RUPTURES OF THE LCL AND POSTEROLATERAL CORNER (PLC).

Abstract

Anatomy & Biomechanics

• Lateral Collateral Ligament (LCL)

  • Primary stabilizer to varus opening

  • Femoral attachment – proximal/posterior to lateral epicondyle

  • Fibular attachment – midway along lateral fibular head

• Popliteus Complex

  • Important stabilizer to posterolateral rotation

  • Stabilizer to varus opening

  • Popliteus attachment on femur

    • 18mm anterior/distal to LCL

    • anterior fifth of popliteal sulcus

  • Popliteofibular ligament (PFL)

    • originates at musculo-tendinous junction of popliteus

    • attaches at medial aspect of fibular styloid

• Mid-Third Lateral Capsular Ligament

  • Secondary stabilizer to varus opening

  • Thickening of lateral midline capsule

  • Meniscotibial portion often injured. Segond injury

• Biceps Femoris Complex

  • Short head of biceps

  • Long head of biceps

• Lateral Meniscus

Injury Mechanism

• Rarely isolated injury

• Usually as a combined ligamentous injury

  • ACL/PLC

  • PCL/PLC

  • Knee Dislocation

• Hyperextension

• Varus blow

• Noncontact twisting

Importance of injury

• Grade III injuries do not heal

• Lead to instability and osteoarthritis

• Compromise cruciate ligament reconstructions

Diagnosis of LCL/PLC injury

• History

  • Usually due to varus/hyperextension injuries

  • 15 % have a peroneal nerve injury

  • Usually combined ligamentous injury

• Clinical exam

  • Varus stress test

  • External rotation recurvatum test

  • Posterolateral drawer test

  • Dial test

  • Reverse pivot shift test

  • Varus thrust gait

• Radiographs

• MRI

• Arthroscopic evaluation

Treatment for acute posterolateral knee injuries

• Acute grade I and II injuries

  • Brace 6 weeks

  • Full ROM

  • Partial weight bearing

• Acute grade III injuries

  • Repair/reconstruct within 2 weeks after injury

  • Attempt anatomic repair

  • Each structure repaired individually

  • Consider augmentation in midsubstance tears

  • Anatomic reconstruction

Treatment For Chronic Grade III Injuries

• Assess for varus alignment

• Proximal tibial opening wedge osteotomy

• Reassess after 6 months for need for soft tissue reconstruction

• Anatomic reconsruction of posterolateral structures

  • Two tailed reconstruction of LCL, PFLand popliteus tendon

  • Biomechanically restores function of native ligaments