9 Common Radiographic Measurements • Measured via a lateral radiograph. • May be referred to as a C2–C7 Cobb angle. Fig. 9.1. Normal cervical lordosis. Line A: drawn in an anteroposterior (AP) direction at the superior end plate of C2. Line B: drawn in an AP direction at the inferior endplate of C7. Line C: drawn in an inferior direction, perpendicular to line A. Line D: drawn in a superior direction, perpendicular to line B. Angle X, measured between lines C and D, represents cervical lordosis. Table 9.1 Normal cervical spine curvature measurements (Fig. 9.1)
9.1 Radiographic Measurements
9.1.1 Cervical Measurements (Fig 9.1, Table 9.1)
Cervical Lordosis
Spine region | Curvature | Measurements |
Cervical | Hypolordosis | < 20 degrees |
Lordosis | 20–40 degrees | |
Hyperlordosis | > 40 degrees |
9.1.2 Thoracic Measurements (Fig 9.2, Table 9.2)
Thoracic Kyphosis
• Measured via a lateral radiograph.
9.1.3 Lumbar Measurements (Fig 9.3, Table 9.3)
Lumbar Lordosis
• Measured via a lateral radiograph.
• May be referred to as a L1–L5 Cobb angle.
9.1.4 Cobb Angle (Fig 9.4)
• Quantifies magnitude of spinal deformities (e.g., scoliosis).
– Cobb angle ≥ 10 degrees = scoliosis.
For more information on scoliosis, see Chapter 12.
Fig. 9.2 Thoracic kyphosis. (a) Normal thoracic kyphosis. (b) Thoracic hyperkyphosis. Line A: drawn in an anteroposterior (AP) direction at the superior endplate of T4. Line B: drawn in an AP direction at the inferior end plate of T12. Line C: drawn in an inferior direction, perpendicular to line A. Line D: drawn in a superior direction, perpendicular to line B. Angle X, measured between lines C and D, represents thoracic kyphosis.
Table 9.2 Normal thoracic spine curvature measurements (Fig. 9.2)
Spine region | Curvature | Measurements |
Thoracic | Hypokyphosis | < 20 degrees |
Kyphosis (Fig. 9.2a) | 20–45 degrees (average 35 degrees) | |
Hyperkyphosis (Fig. 9.2b) | > 45 degrees |
Fig. 9.3 Normal lumbar lordosis. Line A: drawn in an anteroposterior (AP) direction at the superior endplate of L1. Line B: drawn in an AP direction at the inferior end plate of L5. Line C: drawn in an inferior direction, perpendicular to line A. Line D: drawn in a superior direction, perpendicular to line B. Angle X, measured between lines C and D, represents lumbar lordosis.
Table 9.3 Normal lumbar spine curvature measurements (Fig. 9.3)
Spine region | Curvature | Measurements |
Lumbar | Hypolordosis | < 40 degrees |
Lordosis | 40–60 degrees | |
Hyperlordosis | > 60 degrees |
9.1.5 Coronal Balance (Fig 9.5, Table 9.4)
• Radiograph read as if patient standing with back to you (R on R, L on L).
• C7 plumb line (C7PL) = used as a reference to measure displacement of the vertebral bodies from each other and from midline (based on distance from the central sacral vertical line [CSVL]).
• Coronal compensation = C7 vertebral body directly above the S1 vertebral body (despite abnormal spinal curvature).
• Coronal decompensation = C7 vertebral body laterally displaced from above the S1 vertebral body.
9.1.6 Sagittal Vertical Axis (Fig 9.6, Table 9.5)
• Measured via a lateral radiograph.
• Used for cervical sagittal vertical axis (CSVA) or global spine (SVA) measurements.
• C2 plumb line (C2PL) = used as a reference to measure displacement of the cervical vertebral bodies from each other and from midline in a sagittal plane:
– Primary measure of cervical sagittal alignment.
Fig. 9.4 Cobb’s angle. Define upper and lower vertebral levels associated with curvature/deformity. Line A: drawn in an anteroposterior (AP) direction at the superior end plate of the upper vertebral level associated with curvature/deformity. Line B: drawn in an AP direction at the inferior end plate of the lower vertebral level associated with curvature/deformity. Line C: drawn in an inferior direction, perpendicular to line A. Line D: drawn in a superior direction, perpendicular to line B. Angle X, measured between lines C and D, represents Cobb’s angle.
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