(Fig 2-B.11) Secondary Signs of the Acute ACL Tears, Anterior Tibial Translocation

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✅ Secondary Signs of ACL Injury

Secondary signs are highly specific indicators of an Anterior Cruciate Ligament (ACL) injury, though they are less sensitive compared to primary signs. 

While primary signs are pivotal for assessing the ACL's integrity, secondary signs add limited extra diagnostic value. Here's a brief overview:

 

1️⃣ Anterior Translation of the Tibia (Anterior Tibial Translocation):

• The ACL prevents anterior movement of the tibia. In cases of ACL tears, increased anterior tibial translation, known as "anterior tibial translocation," is observed during knee extension.
• In complete ACL ruptures, this sign involves measuring anterior tibial translation relative to the lateral femoral condyle in the mid-sagittal plane.
• Translation between 5 and 7 mm is suggestive, while more than 7 mm confirms an ACL tear. This assessment also reveals potential lateral meniscus (LM) tears.

 

2️⃣ Uncovering of the Posterior Horn of the Lateral Meniscus:

• This sign indicates a posterior displacement of the lateral meniscus's posterior horn relative to the lateral tibial plateau's posterior aspect, hinting at an ACL injury.

 

3️⃣ Coronal Whole PCL and LCL Sign:

• The visibility of the popliteus tendon, Lateral Collateral Ligament (LCL), and biceps femoris on a single coronal image suggests an ACL tear.
• An acute ACL disruption causes anterior tibial translation, altering the LCL's orientation to a more coronal position.

 

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