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 swelling. On examination the tibia sags backwards relative to the femur with both knees flexed at 90 degrees, and the posterior drawer test is positive. The injured structure is:

• A Anterior cruciate ligament
• B Popliteus tendon
• C Lateral collateral ligament
• D Posterior cruciate ligament ✓

Explanation

A dashboard injury drives the proximal tibia posteriorly under a flexed knee, the classic mechanism of posterior cruciate ligament rupture. The posterior sag sign and positive posterior drawer confirm it. An ACL tear gives anterior translation with a positive Lachman and anterior drawer, and an isolated popliteus injury does not produce a sagging tibia.

Reference: Apley's System of Orthopaedics and Fractures, 10th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.