Please confirm topic selection

Are you sure you want to trigger topic in your Anconeus AI algorithm?

Updated: Feb 7 2023

Posterolateral Corner Injury

4.4

  • star icon star icon star icon
  • star icon star icon star icon
  • star icon star icon star icon
  • star icon star icon star icon
  • star icon star icon star icon

(81)

Images
https://upload.orthobullets.com/topic/3012/images/PLC injury_moved.jpg
https://upload.orthobullets.com/topic/3012/images/plc stress radiograph.jpg
https://upload.orthobullets.com/topic/3012/images/MRI poplitues fluid_moved.jpg
https://upload.orthobullets.com/topic/3012/images/42_moved.jpg
https://upload.orthobullets.com/topic/3012/images/plc_anatomy.jpg
https://upload.orthobullets.com/topic/3012/images/er_recurvatum_test.jpg
https://upload.orthobullets.com/topic/3012/images/mri_popliteus.jpg
  • Summary
    • Posterolateral corner (PLC) injuries are traumatic knee injuries that are associated with lateral knee instability and usually present with a concomitant cruciate ligament injury (PCL > ACL).
    • Diagnosis can be suspected with a knee effusion and a positive dial test but MRI studies are required for confirmation.
    • Treatment is generally operative reconstruction of the PLC complex and the associated ligamentous injuries when present.
  • Epidemiology 
    • Incidence
      • Approximately 7-16% knee ligament injuries are to the posterolateral ligamentous complex
        • only 28% of all PLC injuries are isolated
          • usually combined with cruciate ligament injury (PCL > ACL)
        • missed PLC injury diagnosis is common cause of ACL reconstruction failure
  • Etiology
    • Mechanisms
      • blow to anteromedial knee
      • varus blow to flexed knee
      • contact and noncontact hyperextension injuries
      • external rotation twisting injury
      • knee dislocation
    • Associated injuries
      • common peroneal nerve (15-29%)
      • vascular injury
  • Anatomy
    • Posterolateral corner structures
      • three major static stabilizers of the lateral knee
        • lateral collateral ligament (LCL)
          • most anterior structure inserting on the fibular head
          • primary varus stabilizer of the knee
        • popliteus tendon (PLT)
        • popliteofibular ligament
          • originates at the musculotendinous junction of the popliteus
          • anterior and posterior divisions
      • other static stabilizers
        • lateral capsule thickening
          • meniscofemoral and meniscotibial ligaments
        • arcuate ligament (variable)
        • fabellofibular ligament (variable)
      • dynamic structures
        • biceps femoris
          • inserts on the posterior aspect of the fibula posterior to LCL
        • popliteus muscle
        • iliotibial band (ITB)
        • lateral head of the gastrocnemius
    • Function
      • popliteus works synergistically with the PCL to control external tibial rotation, varus, and posterior tibial translation
      • popliteus and popliteofibular ligament function maximally in knee flexion to resist external rotation
      • LCL is primary restraint to varus stress at 5° (55%) and 25° (69%) of knee flexion
    • Definitions
      • arcuate complex includes the static stabilizers: LCL, arcuate ligament, and popliteus tendon
      • Lateral Structures of Knee by Layer
      • Layer 1
      • Iliotibial tract, biceps
      •      common peroneal nerve lies between layer I and II
      • Layer 2
      • Patellar retinaculum, patellofemoral ligament
      • Layer 3
      • superficial:LCL, fabellofibular ligament
      •          lateral geniculate artery runs between deep and superficial layer
      • deep: arcuate ligament, coronary ligament, popliteus tendon, popliteofibular ligament, capsule
  • Classification
    • Modified Hughston classification
      • Modified Hughston classification
      • Examination
      • Findings
      • Grade I
      • 0-5 mm of lateral opening on varus stress
      •  0°-5° rotational instability on dial test
      • Sprain, no tensile failure of capsuloligamentous structures
      • Grade II
      • 6-10 mm of lateral opening on varus stress
      • 6°-10° rotational instability on dial test
      • Partial injuries with moderate ligament disruption
      • Grade III
      • > 10 mm of lateral opening on varus stress, no endpoint
      •  > 10° rotational instability on dial test, no endpoint
      • Complete ligament disruption
  • Presentation
    • Symptoms
      • often have instability symptoms when knee is in full extension
        • difficulty with reciprocating stairs, pivoting, and cutting
    • Physical exam
      • gait exam
        • standing varus alignment
        • varus thrust or hyperextension thrust with ambulation
      • varus stress
        • varus laxity at 0° indicates both LCL and cruciate (ACL or PCL) injury
        • varus laxity at 30° indicates LCL injury
      • dial test
        • > 10° external rotation asymmetry at 30° only consistent with isolated PLC injury
        • > 10° external rotation asymmetry at 30°and 90° consistent with PLC and PCL injury
      • external rotation recurvatum
        • positive when lower leg falls into external rotation and recurvatum when leg suspended by toes in supine patient
        • only identify ~10% of PLC injuries
        • more consistent with combined ACL and PLC injuries
      • posterolateral drawer test
        • performed with the hip flexed 45°, knee flexed 80°, and foot is ER 15°.
        • a combined posterior drawer and external rotation force is then applied to the knee to assess for an increase in posterolateral translation (lateral tibia externally rotates relative to lateral femoral condyle)
      • reverse pivot shift test
        • knee positioned at 90° and external rotation and valgus force applied to tibia
        • as the knee is extended the tibia reduces with a palpable clunk
          • tibia reduces from a posterior subluxed position at ~20° of flexion to a reduced position in full extension (reduction force from IT band transitioning from a flexor to an extensor of the knee)
      • peroneal nerve injury
        • altered sensation to dorsum of foot and weak ankle dorsiflexion
        • approximately 25% of patients have peroneal nerve dysfunction
  • Imaging
    • Radiographs
      • may see avulsion fracture of the fibula (arcuate fracture ) or femoral condyle
      • stress radiographs
        • bilateral varus stress XR in 20° flexion
        • side-to-side difference 2.7-4 mm = isolated LCL tear
        • side-to-side difference > 4 mm = PLC injury
      • long-leg standing radiographs to evaluate alignment
        • required in cases of chronic PLC injury
        • evaluate for triple varus alignment
          • primary varus = tibiofemoral malalignment
          • secondary varus = LCL deficiency with increased lateral opening
          • triple varus = remaining PLC deficient, overall varus recurvatum alignment
        • necessary to determine mechanical axis and if a proximal tibial osteotomy is necessary for correction
    • MRI
      • look for injury to the LCL, popliteus, and biceps tendon
      • in acute injury may see bone bruising of medial femoral condyle and medial tibial plateau
      • coronal oblique thin-slice through the fibular head are best at visualizing the PLC structures
  • Treatment
    • Nonoperative
      • knee immobilization in full extension x4 weeks, then rehabilitation
        • indications
          • grade I PLC injury
          • isolated midsubstance grade II injury
        • technique
          • hinged knee brace locked in extension x4 weeks
          • followed by progressive functional rehabilitation
          • quad strengthening
          • return to sports in 8 weeks
    • Operative
      • PLC repair
        • indications
          • isolated acute grade II PLC avulsion injuries
            • midsubstance repair have 40% failure rate following repair
        • techniques
          • repair of LCL, popliteus tendon and/or popliteofibular ligament should be performed if structures can be anatomically reduced to their attachment site
            • otherwise perform reconstruction
          • augment PLC repair with free graft if repair tenuous
          • avulsion fracture of fibular head can be treated with screws or suture anchors
      • PLC hybrid reconstruction and repair
        • indications
          • grade III midsubstance injuries
          • avulsion injuries where repair is not possible or tissie is poor quality
        • techniques
          • goal is to reconstruct LCL and the popliteofibular ligament using a free tendon graft (semitendinosus or achilles)
          • fibular-based reconstruction (Larson)
            • soft tissue graft passed through bone tunnel in fibular head
            • limbs are then crossed to create figure-of-eight and fixed to lateral femur to a single tunnel
          • trans-tibial double-bundle reconstruction
            • split achilles tendon is fixed to isometric point of the femoral epicondyle
            • one tibia-based limb and one fibula-based limb
            • fibula-limb is fixed to the fibular head with a bone tunnel and transosseous sutures to reconstruct the LCL
            • tibia-limb is brought through the posterior tibia to reconstruct the popliteofibular ligament
          • LaPrade anatomic reconstruction
            • two soft tissue grafts
            • graft #1 reconstructs the LCL and PFL
              • proximal attachment site at anatomic femoral LCL attachment
              • through the fibular head lateral to medial
              • docking into the tibial tunnel posterior to anterior with graft #2
            • graft #2 reconstructs the popliteus tendon
              • proximal attachment site at the anatomic popliteus tendon attachment
              • docking into the tibial tunnel posterior to anterior with graft #1
        • rehabilitation
          • hinged knee brace, nonweightbearing for 6 weeks
          • range of motion protocols differ between surgeons
            • some advocate for passive ROM immediately 0-90°
            • others immobilize for 2 weeks, then begin motion
          • at 6 weeks, begin weightbearing and closed-chain strenghtening
          • return to activities / sports ~ 6 to 9 months
        • outcomes
          • operative treatment has improved outcomes compared to nonoperative treatment
          • repair has higher failure rate than reconstruction
            • particularly for midsubstance injuries, but also for soft tissue avulsions
          • improved outcomes with early treatment
          • anatomic reconstruction restores rotatory stability, but not all varus stability on stress testing
      • PLC reconstruction, +/- ACL reconstruction, +/- PCL reconstruction, +/- HTO
        • indications
          • acute and chronic combined ligament injuries
        • technique
          • PLC reconstruction should be performed at same time or prior to (as staged procedure) ACL or PCL to prevent early cruciate failure
          • valgus high tibial osteotomy
            • indicated in patients with varus mechanical alignment
            • failure to correct bony alignment jeopardizes ACL and PLC reconstruction success
        • rehabilitation
          • postoperatively immobilize and make protected weight bearing for 4 weeks (long leg casts may control leg external rotation better than brace)
          • begin passive ROM at 4 weeks to avoid arthrofibrosis.
          • avoid active hamstring exercises as they will stress the PLC
          • full active extension is allowed
        • outcomes
          • reconstructions have less revision rates and better outcome scores than ligament repair
            • ACL reconstruction + PLC repair 33% achieved IKDC grade A or B compared to 88% of patients who underwent ACL + PLC reconstruction
  • Complications
    • Arthrofibrosis
    • Missed PLC injury
      • failure to identify a PLC injury will lead to failure of ACL or PCL reconstruction
    • Peroneal nerve injury (15-29%)
Card
1 of 1
Question
1 of 13
Private Note

Attach Treatment Poll
Treatment poll is required to gain more useful feedback from members.
Please enter Question Text
Please enter at least 2 unique options
Please enter at least 2 unique options
Please enter at least 2 unique options