2. How do we evaluate Scoliosis ?
In interpreting the imaging features of scoliosis,
it is essential to identify the significance
of vertebrae (apex, end vertebra, neutral vertebra, stable vertebra),
the curve type (primary or secondary, structural or nonstructural),
the degree of angulation (measured with the Cobb method),
the degree of vertebral rotation (with the Nash-Moe method), and
the longitudinal extent of spinal involvement (with the Lenke system).
3.
4. • Radiologic Evaluation - essential initial steps in the evaluation
and treatment of idiopathic scoliosis
• The shortcomings of the Cobb angle
- Vertebral rotation ; key significance in the prognosis and
treatment of scoliotic curves, preoperative and postoperative
assessment, pedicle screws, misplacements
• American orthopedic surgeon John Robert Cobb in 1948
Concept
5. A summary of common radiographic methods of vertebral rotation measurement
7. Degree of vertebral rotation
1. Vertebral body into six equal seg and
identifying the pedicles containg seg
2. As the vertebral body rotates in an evolving curve,
the pedicle outline on the convex side moves on the
vertebral outline, while that of its concave counterpart
becomes less evident, finally disappearing in severe curves.
2. Grade 1 - 4
• The Nash-Moe scale
- The rotation of the apical vertebra
8. • Vertebral rotation according to the Nash-Moe method
• Half vertebra on the side of convexity is then segmented into outer, second, and
inner or midline thirds
• Rotation is quantified on the basis of the location of the convex-side pedicle in one
of these segments and the visibility of the concave-side pedicle, which gradually
disappears as rotation progresses.
B: grade 1 C: grade 2 D: grade 3 E: grade 4A: neutral position
(no rotation)
CONVEX CONCAVE
10. • Frontal x-rays : the patient’s right = the viewer’s right
(the opposite of standard radiographic orientation)
• Sagittal x-rays ; oriented with the patient facing toward the
viewer’s right
• A “positive” direction - assigned to any linear displacements
toward the right, a “negative” direction to those toward the left.
• Any angular displacement in a clockwise is labeled positive
direction ( kyphosis on a lateral x-ray)
and a counterclockwise angular displacement (lordosis) is
negative.
RADIOGRAPHIC CONVENTIONS
12. 1. Minimum set of x-rays- upright and recumbent (typically supine)
AP and lateral long-cassette (36-inch) = the occiput to the femoral
heads
2. Flexibility films (stiffness of a deformity) - supine side-bending
films or lateral- bending films over a bolster for coronal deformities,
supine hyperextension x-rays over a bolster for a kyphotic deformity.
3. Traction views – halter, axilla
4. distance between the source and film, typically 72 inches (180cm),
IMAGE PLANNING AND ACQUISITION
13. 1. Stand upright with the legs fully extended,
the feet positioned at shoulder width.
2. The hips and knees in extension
3. Facing straight ahead,
the upper extremities maximally flexed
at the elbows and the fist positioned
just above the clavicle with the metacarpal
joints facing forward.
4. Leg length discrepancy (> 2cm),
block for level the pelvis
Patient positioning
14. To calculate the Cobb’s angle
1. Identification of apical vertebra
2. Identification of end vertebrae
3. Two lines are drawn along the superior end
plate of the superior end vertebra and
along the inferior end plate of the inferior
end vertebra. If the end plates are
indistinct, the lines may be drawn through
the pedicles.
4. The angle between these two lines (or lines
drawn perpendicular to them).
MEASUREMENT
15. 1. The location of a sagittal or coronal plane deformity is defined
on the basis of the location of the apex of the curve.
2. The apex of curve - the vertebra or disc
(maximally laterally displaced, rotated and minimally angulated, tilted)
3. Thoracic deformity – apex between T2 and the T11–T12 disc
Thoracolumbar deformity - apex (the T12 and L1)
Lumbar deformity - apex (at or distally to the L1–L2 disc)
4. Naming- convex portion, Rt scoliosis (dextroscoliosis),
Lt scoliosis (levoscoliosis)
General Concept
16. 1. Main curve - larger than the others, almost always a structural
curve (not completely straighten out on the flexibility films),
minor curve
2. Compensatory curves- develop in response to the primary
deformity to maintain overall spinal balance, found proximal
and distal to the main curve. (structural or nonstructural)
3. Distal fractional curves- symptomatic lumbar nerve root
compression on the concavity of the compensatory curve
4. The precision or measurement error of Cobb angle
measurements of scoliotic curves is known to be 5’
General Concept
17. 1. Apical vertebra (AV)- the vertebra or disc
(maximally laterally displaced, rotated and minimally tilted)
2. End vertebrae (EV) - the vertebra
(least displaced and rotated and maximally tilted )
- Proximal EV and the Distal EV
3. Stable vertebra (SV)
The pedicles of a stable vertebra both lie between vertical reference
lines drawn from the sacroiliac joints bilaterally (CSVL).
4. Neutral vertebra (NV)
(not rotated in the axial plane, above SV)
* Although one vertebra is often both stable and neutral,
not necessarily so
19. AV- T11/12, EV T7, L2, 100 ‘ Thoracolumbar, Lumbar deformity main curve
Prox EV
Dist EV
SV, NV
SV, NV
20. MEASUREMENT OF CORONAL BALANCE
Apical vertebral translation (AVT)
- lateral displacement of the apex of
a coronal curve relative to CSVL
, horizontal distance between
the centroid of the apical vertebra
and the CSVL.
CSVL – perpendicular to both most superior iliac crest line
• Measuring of Regional coronal balance of curve - AVT
21. 1. The horizontal distance from
the left edge of the x-ray to the CSVL
- the horizontal distance
between the centroid of
the C7 vertebra and the left
edge of the x-ray.
2. Positive result - coronal displacement
to the right
3. Negative value for a displacement
to the left
4. >25mm coronal decompensation by Emamia
• Measuring of Overall coronal plane balance- C7 plumb line
MEASUREMENT OF CORONAL BALANCE
22. 1. Sagittal or lateral translation - measured in millimeters.
2. All translations, or olisthesis - translation of the rostral
vertebra relative to the caudal vertebra.
3. An anterolisthesis, forward subluxation, - recorded as positive,
a retrolisthesis as negative.
