Radiographic MeasurementsNoorulain Iqbal

The identification, classification and

appropriate treatment of spinal deformities depend

to a large degree upon their proper radiographic

evaluation.

1st Step

• The Nature • The Location

Location

• Basis of the location of the apex of the curve

• The apex is the vertebra or disc that is maximally laterally displaced and minimally angulated

• Thoracic : T2 – T11 T12 Disc• Thoracolumbar: T12 – L1

vertebrae• Lumbar: at or distal to L1 –

L2 disc

Cobb Technique

• The angular magnitude of a spinal deformity

• The proximal endplate of the proximal end vertebra and the distal endplate of the distal end vertebra are used.

Apical Vertebral Translation (AVT)

• Lateral displacement of the apex of a coronal curve relative to the center sacral vertical line ( CSVL ).

Sagittal Balance

• C7 Plumb line on lateral xray

• The distal reference point is posterosuperior corner of the sacrum

C2-C7 SVA

• The Distance between – the plumb line of C2 dens tip – plumb line of the center of the C7 upper end plate

C2-C7 Angle

• Angle between– Horizontal line of C2

lower end plate– Horizontal line of C7

lower end plate

T1 SLOPE

• The angle between a horizontal line ( of the radiograph) and the upper end plate of T1

C2-T1 Pelvic Angle (CTPA)

Angle formed by– a line extending

from the center of the C2 vertebral body to the bicoxofemoral axis

– a line from the bicoxofemoral axis to the center of the T1 vertebral body.

T1 Pelvic Angle (TPA)

Angle formed by • a line extending from

the center of T1 to the bicoxofemoral axis

• a line from the bicoxofemoral axis to the center S1 endplate

• Mean: 11.9• >20 = Deformity

Pelvic Parameters

• Pelvic Tilt– Angle between the

vertical and the line through the midpoint of the sacral point to femoral head axis

– Mean pelvic tilt in volunteer population of 13 degrees ( Lafage Spine, 2009)

• Sacral slope – Angle between the

horizontal line and the sacral plate

• Pelvic Incidence– Angle between line

perpendicular to the sacral plate at its midpoint

– The line connecting this point to the femoral head axis