http://upload.orthobullets.com/topic/3011/images/lateral knee ligaments.jpg
http://upload.orthobullets.com/topic/3011/images/knee cross-section.jpg
http://upload.orthobullets.com/topic/3011/images/blood supply to the knee.jpg
http://upload.orthobullets.com/topic/3011/images/lateral structures of the knee.jpg
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  • Injury to the Lateral Collateral Ligament (LCL)
    • also referred to as fibular collateral ligament
  • Epidemiology
    • demographics
      • incidence
        • isolated injury extremely rare
        • 7-16% of all knee ligament injuries when combined with lateral ligamentous complex injuries
          • particularly posterolateral corner (PLC) injury  
  • Mechanism
    • traumatic
      • most frequently result from MVAs and athletic injuries
        • direct blow or force to weightbearing knee 
        • excessive varus stress, external tibial rotation, and/or hyperextension
  • LCL characteristics
    • tubular, cordlike structure
    • dimensions
      • 3-4 mm diameter
      • 66 mm length
    • origin
      • lateral femoral epicondyle
      • posterior and proximal to insertion of popliteus  
    • insertion
      • anterolateral fibula head
      • most anterior structure on proximal fibula 
        • order of insertion from anterior to posterior 
          • LCL → popliteofibular ligament → biceps femoris
  • Blood supply
    • superolateral and inferolateral geniculate arteries 
  • Biomechanics
    • function
      • primary restraint to varus stress at 5° and 25° of knee flexion
        • provides 55% of restraint at 5°
        • provides 69% of restraint at 25°
      • secondary restraint to posterolateral rotation with <50° flexion
      • resists varus in full extension along with ACL and PCL
    • located behind the axis of knee rotation
      • tight in extension and lax in flexion
    • tensile strength: 750 N (valgus)

Lateral Structures of Knee 
Layer I  Iliotibial tract, biceps, fascia 
Common peroneal nerve lies between layers I and II
Layer 2 Patellar retinaculum, patellofemoral ligament  
Layer 3 SuperficialLCL, fabellofibular ligament 
Inferior lateral geniculate artery runs between deep and superficial layers
Deep: arcuate ligament, coronary ligament, popliteus tendonpopliteofibular ligament, capsule 

  • LCL/PLC injury
    • based on quantification of lateral joint opening as compared with the normal contralateral knee with varus stress
      • grade 1+: 0-5 mm lateral opening
      • grade 2+: 6-10 mm lateral opening
      • grade 3+: >10 mm lateral opening without an endpoint
    • sprains classified according to amount of ligamentous disruption
      • grade I: minimal
      • grade II: partial
      • grade III: complete
  • Symptoms
    • instability near full knee extension
    • difficulty ascending and descending stairs
    • difficulty with cutting or pivoting activities
    • lateral joint line pain and swelling
  • Physical exam
    • inspection and palpation
      • ecchymosis and lateral joint line tenderness
    • ROM & stability
      • varus stress test post post
        • varus instability (lateral opening) at 30° flexion only - isolated LCL injury  
        • varus instability at 0° and 30° flexion - combined LCL and/or ACL/PCL injuries
      • dial test post
        • varus instability and increased tibial external rotation at 30° flexion - combined LCL and posterolateral corner injuries 
    • gait assessment post
      • hyperextension or varus (lateral) thrust gait
    • neurovascular exam
      • common peroneal nerve injuries may occur with LCL/PLC injury
  • Radiographs
    • recommended views
      • AP, lateral, and varus stress radiographs 
  • MRI
    • imaging modality of choice
    • provides information about severity (complete vs. partial rupture) and location (avulsion vs. midsubstance tear) 
  • Nonoperative
    • limited immobilization, progressive ROM, and functional rehabilitation
      • indications
        • isolated grade I or II LCL injury (no instability at 0°)
      • outcomes
        • return to sport expected in 6-8 weeks
        • progressive varus/hyperextension laxity can occur with unrecognized associated injuries to the PLC
  • Operative
    • LCL repair/reconstruction +/- PLC/ACL/PCL reconstruction
      • indications
        • grade III LCL injury
        • rotatory instability involving LCL/PLC
        • posterolateral instability (LCL/PLC) at 0° (ACL/PCL rupture)
      • outcomes
        • more favorable outcomes with surgery when injuries are acute
Surgical Techniques
  • Acute LCL repair
    • approach
      • lateral approach to the knee 
        • uses the interval between iliotibial band (superior gluteal nerve) and biceps femoris (sciatic nerve)
        • incise the fascia between ITB and biceps to expose the LCL insertion on the fibular head
        • develop a second interval proximally within ITB to identify the lateral femoral epicondyle
    • techniques
      • suture anchors for repair of avulsed ligament
      • direct suture repair for midsubstance ruptures
      • repair torn or avulsed ligament within 2 weeks of injury (reconstruct if native tissue is irreparable)
  • LCL +/- PLC reconstruction
    • approach
      • lateral approach to the knee
        • between ITB and biceps femoris as detailed above
    • techniques
      • single-stranded graft (bone-patellar tendon-bone) for isolated LCL injuries
      • fibular-based reconstruction (Larson technique) for LCL and popliteofibular ligament reconstruction
        • hamstring graft passed through bone tunnel in fibular head
        • limbs crossed to create figure-of-eight which is then fixed to lateral femur
      • transtibial double-bundle reconstruction of LCL and popliteofibular ligament
        • split Achilles tendon is fixed to the isometric point of the femoral epicondyle
        • one limb is fixed to the fibular head with a bone tunnel and transosseous sutures to reconstruct the LCL
        • second limb is brought through the posterior tibia to reconstruct the popliteofibular ligament
      • anatomic reconstruction of multiple injured structures (LCL, popliteus tendon, and popliteofibular ligament) using bifid graft (split Achilles tendon)
  • Persistent varus or hyperextension laxity
  • Peroneal nerve injury
  • Stiffness
  • Hardware irritation

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