PCL avulsion fracture

PCL avulsion fracture

Normal lateral X ray

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Medial and lateral intercondylar eminences should overlap with each other.

In this X ray: subtle lucency can be seen in AP film and the medial and lateral eminences do not overlap

PCL avulsion fracture

  • PCL anatomy:
    – Originates from the anterolateral medial femoral condyle and inserts on the posterior proximal tibia 
    – Restricts posterior tibial translation
    – Less frequently injured because it is thicker X2 than ACL
      
  • Most common mechanism is direct blow to anterior tibia during MVA (knee in flexion)
  • Grading (Meyers and McKeever):
    Type 1 — Nondisplaced
    Type 2 — Mildly displaced, with elevation of posterior portion of avulsed fragment (hinged mechanism)
    Type 3 — Complete detachment of avulsed fragment

Radiographic features

  • X-ray: mild irregularity in posterior tibial plateau, knee effusion
  • CT: can demonstrate the posterior tibial avulsion
  • MRI: avulsion of the posterior tibial plateau, PCL is otherwise normal. Marrow edema
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    Also can be seen a suprapatellar effusion (hyperintense area above patella) and hyperintense areas in popliteus muscles (muscle strain). PCL is however, intact.

Management

  • Conservative in type 1 and 2
  • Type 3 or associated with other ligamentous injuries eg ACL: Surgical reinsertion and fixation

Long term complication: secondary OA

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