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Posterolateral Corner Injury

Topic updated on 06/23/16 10:28pm
Introduction
  • Approximately 7-16% knee ligament injuries are to the lateral ligamentous complex
    • isolated injuries to PLC are rare
      • usually combined with cruciate ligament injury (PCL > ACL) 
    • missed PLC injury diagnosis is common cause of ACL reconstruction failure
  • Mechanisms
    • blow to anteromedial knee
    • varus blow to flexed knee
    • contact and noncontact hyperextension injuries
    • knee dislocation
  • Associated injuries
    • common peroneal nerve (15-29%)
    • vascular injury
Anatomy
  • PLC structures 
    • static structures
      • LCL (most anterior structure inserting on the fibular head) 
      • popliteus tendon
      • popliteofibular ligament  
      • lateral capsule
      • arcuate ligament (variable)
      • fabellofibular ligament (variable)
    • dynamic structures
      • biceps femoris (inserts on the posterior aspect of the fibula posterior to LCL) 
      • popliteus muscle
      • iliotibial tract
      • lateral head of the gastrocnemius
  • Function
    • popliteus works synergistically with the PCL to control external rotation, varus, and posterior 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 
Layer I 
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
Lateral Structures of Knee by Layer
Layer I   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
  • Grade I (0-5mm of lateral opening and minimal ligament disruption)
  • Grade II (5-10mm of lateral opening and moderate ligament disruption)
  • Grade III (>10mm of lateral opening and severe ligament disruption and no endpoint)
Presentation
  • Symptoms
    • often have instability symptoms when knee is in full extension
      • difficulty with reciprocating stairs, pivoting, and cutting
  • Physical exam
    • gait exam
      • varus thrust or hyperextension thrust
    • varus stress
      • varus laxity at 0° indicates both LCL & 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° & 90° consistent with PLC and PCL injury  q   
    • external rotation recurvatum 
      • positive when lower leg falls into external rotation and recurvatum when leg suspended by toes in supine patient
    • 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 radiography can be done but MRI is diagnostic study of choice 
  • 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 
Treatment
  • Nonoperative 
    • immobilize knee in full extension with protected weightbearing for ~2  weeks
      • indications
        • in isolated PLC Grade I or II injuries
      • followed by progressive functional rehabilitation focusing on quad strengthening with return to sports in 8 weeks
  • Operative
    • PLC repair 
      • indications
        • only in isolated PLC injuries with bony or soft tissue avulsion
        • able to operate within 2 weeks of injury
      • techniques
        • may need to augment PLC repair with free graft
        • avulsion fx of fibular head can be treated with screws or suture anchors
    • PLC reconstruction
      • indications
        • used for most grade III isolated injuries
        • when repair not possible or has poor tissue quality
      • techniques  
        • goal is to reconstruct LCL and the popliteofibular ligament using a free tendon graft (semitendinosus or achilles)
        • fibular-based reconstruction (Larson)
          • hamstring graft passed through bone tunnel in fibular head 
          • limbs crossed to create figure-of-eight and fixed to lateral femur
        • trans-tibial double-bundle reconstruction
          • split achilles tendon is fixed to isometric point of the femoral epicondyle.
          • one branch 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
      • postop
        • 4 weeks of postop cast controls leg ER better than knee brace
      • outcomes
        • operative treatment has improved outcomes compared to nonoperative treatment
        • repair has higher failure rate than reconstruction
        • improved outcomes with early treatment
    • PLC repair/reconstruction,  ACL and/or PCL reconstruction,  +/- HTO
      • indications
        • in 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 
        • 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 than ligament repair
Complications
  • Arthrofibrosis
  • Missed PLC injury
    • failure to identify a PLC injury combined with an ACL injury will lead to failure of the ACL reconstruction
  • Peroneal nerve injury (15-29%)

 

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Qbank (9 Questions)

TAG
(OBQ10.139) A 37-year-old male presents with continued knee pain and instability 6 months status-post combined ACL and PCL reconstruction after a traumatic knee injury. On physical exam his ACL and PCL are intact, however he is noted clinically to have Grade 3 posterolateral corner laxity and varus malalignment of his knee. What is next most appropriate step in management? Topic Review Topic

1. Obtain long leg alignment films for pre-op planning
2. Fibular based posterolateral corner reconstruction
3. Combined tibial-fibular based posterolateral corner reconstruction
4. Physical therapy with closed chained quadriceps exercises, and avoidance of active hamstring exercises
5. Dynamic functional knee bracing

PREFERRED RESPONSE ▶
TAG
(OBQ10.262) A 24-year-old male is involved in a motorcycle accident and sustains a right knee injury. Physical examination manuever performed at 30 degrees of knee flexion is shown in Figure A. Which of the following correctly describes the normal anatomic orientation of the region injured in this patient? Topic Review Topic
FIGURES: A          

1. Popliteus inserts proximal to the LCL on the femur
2. Posterior oblique ligament originates from the adductor tubercle, just posterior and proximal to the medial collateral ligament
3. Biceps femoris inserts posterior to the LCL on the fibular head
4. Popliteofibular ligament inserts lateral to the LCL on the fibular head
5. Deep medial collateral ligament has both meniscofemoral and meniscotibial ligaments

PREFERRED RESPONSE ▶
TAG
(OBQ09.90) Which of the following best describes the anatomic relationships of the lateral collateral ligament in the posterolateral corner? Topic Review Topic

1. inserts directly anterior to popliteofibular ligament on the fibula and courses deep to popliteus
2. inserts anterolaterally to popliteofibular ligament on the fibula and courses superfical to popliteus
3. inserts posteromedially to popliteofibular ligament on the fibula and courses deep to popliteus
4. inserts directly posterior to popliteofibular ligament on the fibula and courses superficial to popliteus
5. inserts posterior and distal to biceps femoris tendon on the fibula and courses superficial to popliteus

PREFERRED RESPONSE ▶
TAG
(OBQ09.260) A 25-year-old male injured his left knee in a motor cycle accident. During examination he is noted to have a positive reverse pivot shift test and a negative posterior drawer. What other examination finding is this patient expected to have? Topic Review Topic

1. Positive anterior drawer test
2. Increased opening to valgus stress at 30 degrees of knee flexion
3. Positive apprehension sign with lateral patellar translation
4. A 10 degree increased external tibial rotation at 30 degrees of knee flexion
5. A 10 degree increased external tibial rotation at 90 degrees of knee flexion

PREFERRED RESPONSE ▶
TAG
(OBQ07.123) A soccer player sustains a knee injury. He is noted to have a significant increase in tibial passive external rotation both at 30 and 90 degrees. Which of the following structures is least likely to be injured? Topic Review Topic

1. Fibular collateral ligament tear
2. Popliteus tendon tear
3. Posterior cruciate ligament tear
4. Arcuate ligament tear
5. Posterior oblique ligament tear

PREFERRED RESPONSE ▶
TAG
(OBQ05.9) The pathologic motion of the lateral tibial plateau moving posteriorly to the femoral condyle on a rotational stress examination is best described by which of the following terms? Topic Review Topic

1. Anterior instability
2. Anteromedial rotatory instability
3. Anterolateral rotatory instability
4. Posteromedial rotatory instability
5. Posterolateral rotatory instability

PREFERRED RESPONSE ▶
TAG
(OBQ04.105) Which of the following injury patterns is most appropriately managed with an immediate postoperative physical therapy regimen that includes no active flexion but does allow active extension from 90 to 0 degrees? Topic Review Topic

1. Patellar tendon repair
2. Anterior cruciate ligament reconstruction
3. Anterior cruciate ligament reconstruction with medial collateral ligament repair
4. Anterior cruciate ligament reconstruction with posterolateral corner repair
5. Posterior cruciate ligament reconstruction with posterolateral corner repair

PREFERRED RESPONSE ▶
TAG
(OBQ04.148) A 34-year-old male presents with right knee pain, swelling, and symptoms of buckling 3 months after being involved in a motorcyle accident. He has a moderate effusion, positive Lachman, positive pivot shift, negative quadriceps active test, and medial sided knee pain with a positive Mcmurray test. Figure A demonstrates his leg external rotation at 30 degrees of flexion, however this deformity corrects with placing the knee at 90 degrees of flexion. Figure B shows a standing extremity alignment radiograph. Figure C shows a sagittal MRI image of the right knee. Appropriate surgical treatment includes each of the following EXCEPT: Topic Review Topic
FIGURES: A   B   C      

1. High tibial osteotomy (HTO)
2. ACL reconstruction
3. Arthroscopic medial partial menisectomy or repair
4. Posterolateral corner reconstruction
5. PCL reconstruction

PREFERRED RESPONSE ▶
TAG
(OBQ04.251) A 20 year-old male football player sustains a knee injury after being hit below the knee while blocking. You suspect a posterolateral corner (PLC) injury, but are also concerned about a posterior cruciate ligament (PCL) tear. Which of the following positive exam findings is indicative of a combined PLC and PCL injury? Topic Review Topic

1. Positive Dial test at 30 degrees of flexion
2. Valgus stress test opening at 0 and 30 degrees of flexion
3. Positive Posterior drawer test
4. Positive Pivot shift test
5. Positive Dial test at 30 and 90 degrees of flexion

PREFERRED RESPONSE ▶



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