PCL injury

Anatomy

  • Origin: Lateral wall of the medial femoral condyle (MFC).
  • Insertion: A sulcus on the posterior tibia, 15mm below the joint line.
  • Menisco-femoral Ligaments:
    • Humphrey’s ligament: Anterior to the PCL.
    • Wrisberg’s ligament: Posterior to the PCL.

Blood Supply

  • Middle geniculate artery.
  • Better vascularity than ACL, leading to better healing of PCL.

Innervation

  • Posterior articular nerve (tibial nerve).

Biomechanics

  • Main restraint: Posterior tibial translation.
  • Secondary stabilizer: Varus-valgus stability.

Mechanism of Injury

  • Direct anterior to posterior blow to tibia with knee flexed (e.g., dashboard injury).
  • Hyperextension or hyperflexion injury.
  • Fall with foot plantarflexed and knee flexed (posterior force on tibia).

Classification

  • Isolated or part of a multi-ligament injury:
    • Completely different management strategies.

Clinical Classification (based on sag degree):

  • Grade 1: Tibia still in front of femoral condyles.
  • Grade 2: Tibia level with femoral condyles.
  • Grade 3: Tibia sagged behind femoral condyles.

Injury Location

  • Mid-substance.
  • Avulsion from tibial insertion.

Concurrent Injuries

  • Often associated with patellofemoral chondral injuries.
  • Other ligament injuries must be ruled out.

History

  • Mechanism as described above.
  • Instability: Especially noticeable when ascending or descending stairs or hills.

Examination

  • Posterior Drawer Test: Positive in grade 3 PCL injuries and multi-ligament injuries.
  • Dial Test:
    • Increased external rotation (ER) of the tibia with the knee flexed to 30 and 90 degrees.
    • 30 degrees indicates PLC (posterolateral corner) involvement alone.
    • 30 and 90 degrees together indicate PLC and PCL involvement.

Management

Goal: Prevent symptomatic instability.

Non-operative Management

  • For the majority of grade 1 and 2 isolated PCL injuries.
  • Even most grade 3 injuries are treated non-operatively.
  • Bony avulsions usually heal well.
  • Rest in extension splint for 4 weeks with limited ROM.
  • Rehabilitation:
    • Closed-chain rehab focusing on quads to pull tibia anteriorly.
    • Graded return to sports.

Operative Management

  • Grade 3 injuries may require reconstruction, even if isolated.
  • Combined ligament injuries require stabilisation.
  • Symptomatic patients are candidates for surgery.

Operative Options

  • Single or double bundle:
    • PCL has anterior-lateral (AL) and posterior-medial (PM) bundles.
    • No proven benefit of the double bundle technique over single bundle.
  • Tibial Onlay or Trans-Tibial Inlay Technique:
    • Tibial onlay may avoid the ‘killer angle’, where a transtibial graft turns acutely towards the femoral tunnel.
    • Trans-tibial inlay requires a long graft.

Graft Selection

  • Hamstrings may not be long enough for transtibial technique.

  • Synthetic or allografts are commonly used (e.g., LARS – Ligament Augmentation and Reconstruction System).

  • Other options:

    • BPTB (Bone-Patellar Tendon-Bone): Tibial onlay as bone block required.
    • Quadriceps Tendon.
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