True Subluxation/Pseudosubluxation

In some cases, there may be displacement of the anterior and posterior lines of the vertebral body due to either true subluxation or pseudosubluxation.

To differentiate between true subluxation and pseudosubluxation:

• Evaluate the anterior soft tissue spaces for signs of swelling
• Draw a line (the spino-laminar line) between C1 to C3, this should pass no more than 1 mm anterior to the spino-laminar line at C2 (the ‘Swischuk line’) [11]. If this distance is >1mm, then suspect subluxation.
• Pseudosubluxation should recover with repositioning of the head in extension

Learning Bite

Pseudosubluxation occurs most commonly at C2/3. It may be distinguished from true subluxation by the use of the Swischuk line, the absence of anterior soft tissue swelling and resolution in extension. If doubt persists, expert advice should be sought.