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