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Alar Ligament Avulsion

Case Detail

Anatomy: Brain-Spine
Joseph Junewick, MD FACR
Diagnostic Category: Trauma
Created: over 6 years ago
Updated: over 5 years ago
Tags: PEDS
Modality/Study Types: CT
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12 year old football player with neck pain.

Case Images


Alar Ligament Avulsion


CT – Axial and coronal reformat images show a cortical avulsion fracture emanating from the inferior aspect of the occipital condyle and the atlas tubercle on the right.


The alar ligaments connect the lateral aspect of the dens and the medial inferior aspect of the occipital condyles and/or the lateral mass of the atlas. The alar ligaments are usually orientated horizontally or superolaterally from the dens in the coronal plane. The main function of the alar ligaments is to limit rotation to the contralateral side. Tear of the alar ligament results in a higher range of motion to the contralateral side and rotational instability.


Pfirrmann CWA, Binkert CA, Zanetti M, et al. MR Morphology of Alar Ligaments and Occipitoatlantoaxial Joints: Study in 50 Asymptomatic Subjects. Radiology (2002); 218:133-137.

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