Structural Analysis Flashcards

On a lateral cervical radiograph, a step-off in George's line most directly suggests:

Answer: Anterior or posterior vertebral translation

George's line follows the posterior vertebral bodies, so a discontinuity indicates segmental translation.

On cervical flexion-extension views, sagittal translation greater than about how many millimeters suggests instability according to White and Panjabi criteria?

Answer: 3.5 mm

White and Panjabi considered more than 3.5 mm of sagittal translation a sign of cervical instability.

Why is the posterior tangent method often preferred to the Cobb method for sagittal cervical curve analysis in CBP?

Answer: It describes segmental geometry more precisely and is less affected by endplate irregularities

Posterior body lines are more reliable landmarks and reflect segmental curve geometry better than Cobb endplate lines.

Patient axial rotation during a lateral radiograph commonly produces which artifact?

Answer: Double contours of the posterior vertebral body margins

Rotation separates the left and right posterior body margins into double outlines, so the midpoint is digitized.

In the Harrison ideal cervical model, which vertebral alignment is used as the sagittal balance reference?

Answer: C2 positioned vertically above C7

In the ideal model C2 sits vertically over C7, so any forward offset indicates anterior head translation.

Which cervical curve pattern has lordosis in one region and kyphosis in another region of the neck?

Answer: S-shaped curve

An S-shaped cervical curve has opposite curvatures in the upper and lower cervical regions.

Why are the upper thoracic segments often difficult to measure on a lateral thoracic or full-spine film?

Answer: The shoulders and soft tissue overlap obscure the vertebrae

Superimposed shoulder girdle and soft tissue reduce visibility of T1-T3 on lateral views.