A passenger in a head-on road traffic accident strikes his knee against the dashboard. He walks in with pain behind the knee and mild effusion. Examination shows increased posterior translation of the tibia on the posterior drawer test, graded 2+. The structure most likely injured is:
- A Anterior cruciate ligament
- B Lateral collateral ligament
- C Posterior cruciate ligament ✓
- D Popliteus tendon
Correct answer: C. Posterior cruciate ligament
Explanation
A dashboard injury drives the proximal tibia posteriorly against a flexed knee, the classic mechanism of posterior cruciate ligament rupture. The posterior drawer test is the most reliable clinical test for the PCL, and grade 2 indicates the tibia drops level with the femoral condyles. ACL injuries follow hyperextension or pivot mechanisms with anterior translation, while isolated LCL and popliteus injuries produce varus instability and posterolateral rotatory signs respectively.
Reference: Bailey and Love's Short Practice of Surgery, 27th ed.
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Written and medically reviewed by the StethoPrep medical team.