Thursday, October 29, 2009

Secondary Signs of Anterior Cruciate Ligament Injury

  • Kissing subchondral bone bruises involving one or both posterior tibial plateaus and the corresponding anterior femoral condyle(s) suggests an ACL injury less than 2-months-old.
  • Posterolateral tibial bone bruise by itself has a high predictive value for ACL tear in adults (not so much in pediatric patients due to laxity of the ACL).
  • Posterolateral injuries: lateral collateral ligament, lateral capsule, and popliteus tendon injuries; the Segond fracture (100% associated with ACL tear); and avulsion of fibular head.
  • Avulsion at Gerdy's tubercle (insertion of the iliotibial band).
  • Hemarthrosis: 75% of acute hemarthroses of the knee are due to ACL tears.
  • Hyperangulation of the PCL: A line drawn tangent to the posterior border of the PCL fails to intersect the distal 4-6 cm of the femur.
  • Anterior subluxation of tibia: Lines drawn across posterior margins of lateral tibia and lateral femoral condyle in the region of the mid-lateral tibial compartment are more than 7 mm apart.
  • Posterior subluxation of the posterior horn of the lateral meniscus relative to posterior margin of the lateral tibial condyle.
  • O'Donoghue's unhappy triad: ACL tear, MCL injury, and medial meniscus tear.

Refereces

Musculoskeletal Radiology: The Requisites. Third edition. Chapter 13, pages 234-237.

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