PCL 2.jpg

  • May be isolated or combined and often go undiagnosed in the acutely injured knee

  • Mechanism

    • direct blow to proximal tibia with a flexed knee (dashboard injury)

    • noncontact hyperflexion with a plantar-flexed foot 

    • hyperextension injury

Pathoanatomy

  • PCL is the primary restraint to posterior tibial translation

  • functions to prevent hyperflexion/sliding

  • isolated injuries cause the greatest instability at 90° of flexion

PCL deficiency leads to increased contact pressures in the patellofemoral and medial compartments of the knee due to varus alignment 

 

Classification based on posterior subluxation of tibia relative to femoral condyles (with knee in 90° of flexion)

  • Grade I (partial)

    • 1-5 mm posterior tibial translation

    • tibia remains anterior to the femoral condyles

  • Grade II (complete isolated)

    • 6-10 mm posterior tibial translation

    • complete injury in which the anterior tibia is flush with the femoral condyles

  • Grade III (combined PCL and capsuloligamentous)

    • >10 mm posterior tibial translation

    • tibia is posterior to the femoral condyles and often indicates an associated ACL and/or PLC injury

PCL 3.png

Symptoms and clinical findings

  • posterior knee pain

  • instability ( may be subtle or absent in isolated PCL)

  • varus/valgus stress

    • laxity at 0° indicates MCL/LCL and PCL injury

    • laxity at 30° alone indicates MCL/LCL injury

  • Posterior Sag sign

  • Posterior drawer test

  • Quadriceps active test

  • Dial test

    • > 10° ER asymmetry at 30° & 90° consistent with PLC and PCL injury

    • > 10° ER asymmetry at 30° only consistent with isolated PLC injury

Posterior sag

Posterior sag

Posterior drawer

Posterior drawer

Imaging

  • Xrays : AP + L + Stress view

  • MRI

PCL xrays.jpg
PCL irm.jpg

Treatment

  • Non operative:

    • protected weight bearing & quadriceps rehab. For grade 1 and grade 2

    • relative immobilization in extension for 4 weeks: grade 3

  • Operative: Reconstruction

    • if bony avulsion (may consider Open reduction and internal fixation)

    • if functionally unstable knee

    • if multiligament knee injury

  • Operative: high tibial osteotomy for chronic PCL lesion : medial opening + increasing the tibial slope

PCL 5.jpg
increasing Tibial slope.png

Rehabilitation:

  • immobilize in extension early and protect against gravity: early motion should be in prone position

  • Rehabilitation: focus on quadriceps rehabilitation ( and not hamstrings !)