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Posterolateral Corner Injury

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Other Names

  • Posterolateral Corner Injury of the Knee
  • PLC injury




  • One study estimates 5 to 9% of all knee injuries[1]
  • 7-16% of ligamentous knee injuries involve the PLC (need citation)
    • Of those, only 28% are isolated (need citation)


  • General
    • Injuries to PLC can result in instability posteriorly and lateraly
  • Mechanism of injury
    • High speed: motor vehicle accidents, ATV
    • Low speed: sporting events, falls


  • Biomechanics
    • Direct hit on the proximal tibia with knee in stretched condition may cause an isolated posterolateral injury
    • Hyperextension and varus forces can also cause an injury to the posterolateral ligaments
    • Posterior stress force when the knee is in flexed condition or the tibia is in externally rotated position
    • Lateral dislocation of the knee joint can cause a severe injury to the posterolateral structures
  • Activities with significant force
    • MVC
    • Falls
    • Rugby, football


Associated Injuries

Risk Factors

  • Sports
    • Rugby
    • Football

Differential Diagnosis

Clinical Features

  • History
    • Important to clarify the history and mechanism of injury
    • Pain on the posterolateral aspect of the knee
    • A sensation of instability of the knee, for example giving way on stairs or in extension
    • In chronic cases, medial or lateral joint line pain might be present
    • Uncommonly, parasthesia or foot drop
  • Physical Exam: Physical Exam Knee
    • Ecchymosis, knee effusion
    • In standing position or during gait, may observe varus alignment[6]
    • Important to evaluate integrity of peroneal nerve (dorsal sensation, dorsiflexion)
  • Special Tests



  • Standard Radiographs Knee
    • Often normal, used to exclude other injuries
  • Finding
    • Widening of the lateral joint space widening
    • Tibial metaphysical avulsion fracture
    • Tibial plateau fracture
  • Standing long leg view
    • Consider to evaluate limb alignment
  • Stress Radiographs Knee
    • Can be helpful for the diagnosis of PLC injuries
    • Varus stress radiographs with the knee at 20° of flexion to provide objective measures of lateral compartment gapping
    • Opening of more than 4 mm may indicate a grade III PLC injury[7]
    • Kneeling PCL stress radiographs may also be useful


  • Useful to evaluate PLC structures
  • Optimal view
    • The T2-weighted coronal oblique view is most useful for evaluating PLC
    • Coronal or sagittal view less valuable
  • MRI is also helpful to evaluate acute or subacute PLC injuries
    • Sensitivity is >90% when obtained under 12 weeks[1]
    • Only 26% of patients were correctly diagnosed when an MRI was taken after 12 weeks
    • Therefore, MRI should be obtained within 12 weeks if possible


  • Can be useful to evaluate posterolateral corner
    • Examine: popliteus complex, coronary ligament of the lateral meniscus, and posterolateral capsul
  • Findings
    • Drive through sign: more than 1cm lateral joint opening under varus stress to the knee joint
    • Popliteal hiatus widening during internal rotation of the tibia[8]
    • Tears of the inferior and superior popliteomeniscal fascicle
    • Abnormal popliteomeniscal motion during rotation


Fanelli and Larson Classification[9]

  • Type A
    • Exam: 10° increase in external rotation of the tibia
    • Injured Structures: PFL, popliteus tendon
  • Type B
    • Exam: 10° increase in external rotation of the tibia
    • Exam: Slight varus relaxation (5–10 mm increase in varus load test)
    • Injured Structures: LCL, PFL, popliteus tendon
  • Type C
    • Exam: 10° increase in external rotation of the tibia
    • Exam: Severe varus relaxation (>10 mm increase in varus load test)
    • Injured Structures: LCL, capsule avulsion, cruciate ligament, PFL, popliteus tendon

Modified Hughston Classification[10]

  • 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 end point
    • > 10° rotational instability on dial test, no end point
    • Complete ligament disruption



  • Indications
    • Grade I PLC injury
    • Consider in isolated Grade II PLC injuries
  • Hinged Knee Brace and crutches
    • Locked in extension for 4 weeks to 6 weeks
    • Protected weight bearing
  • Physical Therapy
    • Isometric quadriceps strengthening may begin early
    • Progressive functional rehabilitation can begin around 6 weeks


  • Indications
    • Grade II with other structural injuries
    • Grade III
  • Technique
    • Repair
    • Anatomic Reconstruction
    • Non-anatomic Reconstruction
  • Goal
    • Achieve posterolateral stability
  • Acute injury
    • Defined as within 3 weeks of injury
  • Chronic injury
    • Defined as greater than 3 weeks from injury
    • Can be more challenging due to formation of scar tissue

Rehab and Return to Play


  • General
    • Goal: protect the reconstructed or repaired ligament structures
    • Early: strengthening of the quadriceps muscle, protection of the patellofemoral joint
  • Postoperative
    • Patient immobilized, non-weight bearing for 6 weeks
    • Patient may wear an immobilizer brace with the knee in extension, except for range of motion exercises[11]
  • Early rehab
    • Initial rehabilitation focuses on restoring tibiofemoral, patellofemoral ROM
    • 0-2 weeks: passive ROM exercises are performed from 0° to 90°, then progress as tolerated
    • 6 weeks: begin spinning on a stationary bike and wean off crutches
  • Late rehab
    • Goal: full weight bearing, focus on developing muscular endurance
    • Begin with closed chain strengthening, then progressive resistance training with isolated muscle groups
    • Isolated hamstring exercises limited until 4 months to prevent stress on reconstruction
    • Advance to running, agility drills as strength and power are restored

Return to Play

  • Typically occurs around 6 months

Complications and Prognosis


  • Repair
    • Primary repair outcomes appear best when done acutely per Shelbourne et al[12]
    • Likely due to easier to identify anatomy, less scar tissue[13]
    • Baker et al: 13 patients with primary repair had good objective, functional outcomes[14]
    • Krukhaug et al: compared to nonoperative management, repair had less instability[15]
  • Reconstruction
    • Ibrahim et al: 20 patients showed improved outcome scores, mean Lysholm score was 90 points at the 44-month follow-up[16]
    • Stannard et al: higher failure rate in the repair group than in the reconstruction group[17]
    • Levy et al.55: failure rate lower in reconstruction compared to repair in cases of multiligament knee injury patients who underwent repair, followed by delayed reconstruction of the cruciate ligaments[18]


  • Failure to identify PLC injury
    • Missed diagnosis will lead to other graft failures
  • Peroneal Nerve Injury
    • Seen in 13% to 16% of cases in small cohorts[19][20]
  • Persistent Instability
    • Related to reconstruction technique with failure rate higher with primary repair vs reconstruction
    • Also to varus malalignment
  • Postop
  • Inability to return to sport
  • Chronic pain

See Also


  1. 1.0 1.1 Pacheco RJ, Ayre CA, Bollen SR. Posterolateral corner injuries of the knee: a serious injury commonly missed. J Bone Joint Surg Br. 2011;93:194–7.
  2. Chahla J, Moatshe G, Dean CS, LaPrade RF. Posterolateral corner of the knee: current concepts. Arch Bone Jt Surg. 2016;4:97–103
  3. Cooper, Jonathan M., Peter T. McAndrews, and Robert F. LaPrade. "Posterolateral corner injuries of the knee: anatomy, diagnosis, and treatment." Sports medicine and arthroscopy review 14.4 (2006): 213-220.
  4. Geeslin, Andrew G., Samuel G. Moulton, and Robert F. LaPrade. "A systematic review of the outcomes of posterolateral corner knee injuries, part 1: surgical treatment of acute injuries." The American journal of sports medicine 44.5 (2016): 1336-1342.
  5. Chahla, Jorge, et al. "Posterolateral corner of the knee: current concepts." Archives of Bone and Joint Surgery 4.2 (2016): 97.
  6. Bae WH, Ha JK, Kim JG. Treatment of posterolateral rotatory instability of the knee. J Korean Knee Soc. 2010;22:1–10.
  7. LaPrade RF, Heikes C, Bakker AJ, Jakobsen RB. The reproducibility and repeatability of varus stress radiographs in the assessment of isolated fibular collateral ligament and grade-III posterolateral knee injuries: an in vitro biomechanical study. J Bone Joint Surg Am. 2008;90:2069–76.
  8. Kim JG, Moon HT, Hwang IH, Kim JH, Song JK. Arthroscopic evaluation of posterolateral rotatory instability of the knee. J Korean Orthop Assoc. 2003;38:29–33.
  9. Fanelli GC, Larson RV. Practical management of posterolateral instability of the knee. Arthroscopy. 2002;18(2 Suppl 1):1–8. doi: 10.1053/jars.2002.31779.
  10. Hughston JC, Andrews JR, Cross MJ, Moschi A. Classification of knee ligament instabilities: part II. The lateral compartment. J Bone Joint Surg Am. 1976;58:173–9.
  11. Crespo B, James EW, Metsavaht L, LaPrade RF. Injuries to posterolateral corner of the knee: a comprehensive review from anatomy to surgical treatment. Rev Bras Ortop. 2014;50:363–70.
  12. Shelbourne KD, Haro MS, Gray T. Knee dislocation with lateral side injury: results of an en masse surgical repair technique of the lateral side. Am J Sports Med. 2007;35:1105–16.
  13. pitzer E, Doyle JB, Marx RG. Outcomes of surgical treatment of posterolateral instability of the knee. J Knee Surg. 2015;28:471–4.
  14. , Hughston JC. Acute combined posterior cruciate and posterolateral instability of the knee. Am J Sports Med. 1984;12:204–8.
  15. Krukhaug Y, Mølster A, Rodt A, Strand T. Lateral ligament injuries of the knee. Knee Surg Sports Traumatol Arthrosc. 1998;6:21–5.
  16. Ibrahim SA, Ghafar S, Salah M, Abo Alnas M, Al Misfer A, Farouk H, Al Haran H, Khirait S. Surgical management of traumatic knee dislocation with posterolateral corner injury. Arthroscopy. 2013;29:733–41.
  17. Stannard JP, Brown SL, Farris RC, McGwin G, Jr, Volgas DA. The posterolateral corner of the knee: repair versus reconstruction. Am J Sports Med. 2005;33:881–8.
  18. Levy BA, Dajani KA, Morgan JA, Shah JP, Dahm DL, Stuart MJ. Repair versus reconstruction of the fibular collateral ligament and posterolateral corner in the multiligament-injured knee. Am J Sports Med. 2010;38:804–9.
  19. LaPrade RF, Terry GC. Injuries to the posterolateral aspect of the knee. Association of anatomic injury patterns with clinical instability. Am J Sports Med. 1997;25:433–8.
  20. Krukhaug Y, Mølster A, Rodt A, Strand T. Lateral ligament injuries of the knee. Knee Surg Sports Traumatol Arthrosc. 1998;6:21–5.
Created by:
John Kiel on 7 July 2019 05:44:03
Last edited:
4 October 2022 15:50:54