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CASE - Knee pain and instability
Review the case, then read notes below.
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TEACHING POINTSThe fibular collateral ligament can be visualized in its entire course in the coronal plane
![](/images/link.png)
suggesting anterior translation of the lateral tibia relative to the femur.
This is confirmed in the sagittal plane: the posterolateral tibia is approx 9 mm anterior to a vertical line tangent to the posterior lateral femoral condyle
![](/images/link.png)
, the PCL is more vertical distally
![](/images/link.png)
, and there is a mild bi-concavity of the sulcus terminalis
![](/images/link.png)
that could represent an old kissing contusion (soft call).
The mid ACL is irregular
![](/images/link.png)
, compatible w/ partial tear, more specifically, the anteromedial bundle
![](/images/link.png)
, which helps stabilize against rotational load, and likely posterolateral.
Knowledge of the 2 anatomic bundles of the ACL is important for better stratifying partial tears for potential selective-bundle ACL reconstructions because single-bundle reconstructions restore anteroposterior tibial translation, but not tibial rotation.
This case has not yet been confirmed arthroscopically.
REFERENCES:1 Casagranda et al. Normal Appearance and Complications of Double-Bundle and Selective-Bundle Anterior Cruciate Ligament Reconstructions Using Optimal MRI Techniques. AJR:192, May 2009.
Accession: CL0475
Study description: MRI LOWER EXTREMITY JOINT W/O CONTRAST - RIGHT