Scoliosis Research Society (SRS)
Scoliosis Research Society (SRS)
An International Organization Dedicated to the Education, Research and Treatment of Spinal Deformity
Our Mission is to Foster Optimal Care for All Patients with Spinal Deformities
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SRS Terminology Committee and Working Group on Spinal Classification Revised Glossary of Terms

By the Working Group on 3-D Classification (Chair Larry Lenke, MD), and the Terminology Committee, March 2000
   
Angle of trunk inclination (ATI)
(Figure 1)
with the trunk flexed to the horizontal,the angle between the horizontal and the plane across the back at the greatest elevation of a rib prominence or lumbar prominence, as measured by an inclinometer (scoliometer)
Apical disc
(Figure 2)
in a curve, the disc most deviated laterally from the vertical axis of the patient that passes through the sacrum,  i.e. from the central sacral line
Apical vertebra
(Figure 2)
in a curve, the vertebra most deviated laterally from the vertical axis that passes through the patient's sacrum, i.e. from the central sacral line
Apical vertebral/disc lateral deviation
(from the global vertical axis)
(Figure 2)
distance in millimeters from the central sacral line to the mid-point of the apical body/disc (See Note 3). In a decompensated patient, the apical translation should be measured from the central sacral line for the thoracolumbar and lumbar spine, and from the C7 plumb line for the thoracic spine
Café-au-lait spots light brown or black irregular areas of skin pigmentation with smooth margins. If 6 or more are  1.5 cm or more in diameter, neurofibromatosis is suggested
Central sacral line
(Figure 3)
the vertical line in a frontal radiograph that passes through the center of the sacrum (identified by suitable landmarks preferably on the first sacral segment)
Cervical scoliosis
(Figure 4)
scoliosis having its apex at a point between C1 and the C6-C7 disc
Cervical-thoracic scoliosis 
(Figure 4)
scoliosis having its apex at C7, T1, or the intervening disc space
Chest cage asymmetry non-scoliotic any clinical asymmetry of the posterior chest wall associated with a radiographic Cobb measurement of < 10º
Chronologic definition of idiopathic scoliosis presentations: infantile scoliosis - presenting from birth through age 2+11
juvenile scoliosis - presenting from age 3 through age 9+11 
adolescent scoliosis - presenting from age 10 through age 17+11
adult scoliosis - presenting from age 18 and beyond
Compensation
(Figure 3)
the vertical alignment of the mid point of C7 with the mid-point of the sacrum in the coronal plane (equates with the term coronal balance)
i.e. horizontal distance of the C-7 mid point from the central sacral line
Compensatory curve a minor curve above or below a major curve that may or may not be structural
Congenital scoliosis scoliosis due to congenitally anomalous vertebral development
Curvature Measurement 
(See Note 1)
Cobb Method: angle between lines drawn on endplates of the end vertebrae (superior endplate of upper end vertebra; inferior endplate of lower end vertebra)
Decompensation Compensation greater than a specified threshold value 
Double structural scoliosis a spine with two structural scolioses 
Double thoracic scoliosis a double structural scoliosis with the apex of each curve located in the thoracic spine
End vertebrae
(Figure 2)
The vertebrae that define the ends of a curve in a frontal or sagittal projection
Cephalad end vertebra: The first vertebra in the cephalad direction from a curve apex whose superior surface is tilted maximally toward the concavity of the curve
Caudad end vertebra: the first vertebra in the caudad direction from a curve apex whose inferior surface is tilted maximally toward the concavity of the curve
Fixed pelvic obliquity pelvic obliquity which implies a non-idiopathic diagnosis, or intrapelvic cause
Gibbus a localized kyphosis
Hyperkyphosis a kyphosis greater than the normal range
Hypokyphosis a kyphosis of the thoracic spine less than the normal range
Hyperlordosis a lordosis greater than the normal range
Hypolordosis a lordosis of the cervical or lumbar spine less than the normal range
Hysterical scoliosis a deformity of the spine that develops as a manifestation of a conversion reaction
Idiopathic scoliosis defined radiographically as a lateral curvature of the spine greater than or equal to 10º Cobb with rotation, of unknown etiology
Iliac apophysis the apophysis along the crest of the ilium
Inclinometer an instrument used to measure the angle of trunk cage inclination in the forward bend position
Inflection vertebra
(Figure 2)
where curves change direction from convex to concave and vice versa
Kyphosis a posterior convex angulation of the spine. (For recommended measurement procedure, see Note 4)
Kyphoscoliosis a non idiopathic scoliosis associated with an area of true hyperkyphosis
Lordoscoliosis a scoliosis associated with an area of lordosis
Lordosis an anterior convex angulation of the spine. (For recommended measurement procedure, see Note 4)
Lumbar scoliosis
(Figure 4)
a scoliosis that has its apex at a point between the L1-L2 disc space through the L4-L5 disc space
Lumbosacral scoliosis 
(Figure 4)
a scoliosis that has its apex at L5 or below
Major curve the curve with the largest Cobb measurement on upright long cassette coronal x-ray of the spine
Minor curve
(Figure 2)
any curve that does not have the largest Cobb measurement on upright long cassette coronal x-ray of the spine
Myopathic scoliosis a scoliosis due to a muscular disorder
Neuromuscular scoliosis a scoliosis due to either a neurologic or muscular disorder
Neuropathic scoliosis a scoliosis due to a neurologic disorder
Neutral vertebra
(Figure 3
a vertebra without axial rotation (In reference to the most cephalad and caudal vertebrae that are not rotated in a curve)
Non-structural curve a measured curve in the coronal plane in which the Cobb measurement corrects past zero on supine lateral side bending x-ray
Paravertebral height difference
(Figure 1)
with the trunk flexed to the horizontal, the difference in height (in millimeters) between two points on the posterior rib cage. The two points are identified as (1) the most prominent point (2) a point on the opposite side of the back, at an equal distance from the midline
Pelvic inclination
(Figure 5)
deviation of the pelvic outlet from the vertical in the sagittal plane. Measured as an angle between the line from the top of the sacrum to the top of the pubis, and a horizontal line perpendicular to the lateral edge of the standing radiograph
Pelvic obliquity
(Figure 5)
angulation of the pelvis from the horizontal in the frontal plane, possibly secondary to a contraction below the pelvis, e.g. of the hip joint. If this angulation is due to a leg length inequality, then the leg lengths should be equalized to create a level pelvis for measurement purposes
Pelvic axial rotation rotation of the pelvis in the transverse plane around the vertical axis of the body
Radiographic plumb line
(See Note 2)
the vertical line drawn on a radiograph that is used to measure compensation
Regional apical vertebral translation
(Figure 6)
distance in millimeters from the line joining the midpoints of the upper and lower end vertebrae of the measured curve to the midpoint of the apical vertebral body or disc
Rib rotational prominence the prominence of the ribs best exhibited on forward bending
Risser sign in the frontal plane x-ray of the pelvis, the state of ossification of the iliac apophysis used to denote the degree of skeletal maturity: 0-no evidence of ossification of the apophysis; 1-25% excursion; 2-50% excursion; 3-75% excursion; 4-100% excursion; 5-fusion of the apophysis to the iliac crest
Sacral inclination
(Figure 5)
the angle between the line along the posterior border of S1 and the vertical lateral edge of a lateral standing radiograph (or between perpendiculars to these lines)
Sacral obliquity
(Figure 5)
an angular deviation of the sacrum from the line drawn parallel to a line across the femoral heads on a supine AP view of the sacrum
Sagittal spinal balance
(Figure 8)
alignment of the midpoint of the C7 body to the posterior superior corner of the sacrum on an upright long cassette lateral radiograph of the spine
Scoliosis a lateral curvature of the spine
Skeletal age the age obtained by comparing PA x-ray of the left wrist and hand with the standards of the Gruelich and Pyle atlas
Stable vertebra
(Figure 6)
the thoracic or lumbar vertebra cephalad to a lumbar scoliosis that is most closely bisected by a vertically directed central sacral line assuming the pelvis is level.
Structural curve a measured spinal curve in the coronal plane in which the Cobb measurement fails to correct past zero on supine maximal voluntary lateral side bending x-ray
Thoracic scoliosis
(Figure 4)
a scoliosis that has its apex at a point between the T2 vertebral body through the T11-T12 disc
Thoracogenic scoliosis
spinal curvature attributable to disease or operative trauma in or on the thoracic cage
Thoracolumbar scoliosis
(Figure 4)
a scoliosis with its apex at T12, L1, or the intervening T12-L1 disc
Vertebral Axial Rotation transverse plane angulation of a vertebra; one method of measurement is with the Perdriolle technique (in degrees) (Figure 7)
Vertebral tilt
(Figure 2)
vertebral angulation to the horizontal in the coronal plane, measured from specified landmarks on the vertebra in a standing radiograph(normally lines drawn on the upper or lower endplate)
Note 1:
Drawing curve (Cobb) measurements - the major curve should be measured first. It is normally measured from the superior endplate of the upper end vertebra, to the inferior endplate of the lower end vertebra. Minor curves above or below the major curve will utilize the same upper or lower inflection vertebra.

If the endplates cannot be visualized, then the inferior portion of the pedicles should be utilized as landmarks.
In congenital curves, it may be necessary to draw a perpendicular line to the lateral phpect of the vertebral body to determine the upper and lower end vertebra tilt.

Note 2:
Radiographic plumbline - the preferred technique involves drawing a vertical line up from the mid-point of the sacrum and measuring the distance from this line to the C7 vertebral body center in millimeters. The alternate technique involves drawing a vertical line or dropping a plumbline from the C7 spinous process down to the sacrum with the distance to the mid-point of the sacrum measured in millimeters. In both instances, it is assumed that the vertical edge of the radiograph is a true vertical.

Note 3:
The mid point of a vertebra body/disc is determined by drawing a cross (X) in the body/disc.
Draw a line from the upper left corner to the lower right of the body/disc and a line from the upper right to the lower left of the body/disc. The intersection is the mid-point.

Note 4:
The recommended measurement of thoracic kyphosis from a lateral radiograph is the angle between the superior endplate of the highest measurable thoracic vertebra, usually T-2 or T-3, and the inferior endplate of T-12.
The recommended measurement of lumbar lordosis from a lateral radiograph is the angle between the superior endplate of L-1 and the superior endplate of S-1.