Happy New Year!!!!
Inevitably the coming days will be a pain in the neck, or at least present you with the opportunity to evaluate kids with pains in their necks. When that happens, recall that kids have several normal radiographic findings that would be abnormal in adults: the one that will cause often catch your eye is pseudosubluxation (or at least you hope it is “pseudo.”

For more information on C-Spines… see Aug 20,2010 Morsel.


– Refers to the normal mobility of the cervical vertebrae, IN FLEXION, which may appear pathologic
– Occurs in children <8 yrs of age (> 8yrs, c-spine films should be similar to adults)
– Present at C2-C3 level (40%) or at the C3-C4 level (14%)

How to distinguish between Pseudosubluxation and Pathologic Subluxation

> The displacement should only occur in flexion (Not extension)
– most pediatric c-spine films are in flexion due to the occiput

> Swischuk Line
– Line that is drawn from anterior aspect of C1-C3 spinous processes
– This line should be within 2mm of the anterior aspect of the C2 spinous process

> Spinal-Laminar Line
– The line drawn connecting the lamina of C1, C2, and C3 should remain intact even in flexion
– If you suspect that the misalignment represents pseudosubluxation, than you can reposition in extension and if the misalignment resolves it is consistent with pseudosubluxation. But be careful, if the mechanism is concerning, obtain CT to r/o hangman’s fracture.
Anterior displacement of C2 in children: physiologic or pathologic.
LE Swischuk. Radiology. Vol 122(3) 1977. p 759-763.


Sean M. Fox
Sean M. Fox
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