Spine

X-Ray

Atlanto-Dens Interval (ADI, Cervical C1–C2)

Adults: <3 mm; Children: <5 mm

Normal Value

Increased = transverse ligament rupture, RA, trauma, Down’s syndrome

Prevertebral Soft Tissue Thickness (Cervical)

C2: <7 mm; C6: <22 mm

Normal Value

Thickening suggests hematoma, abscess, tumor, or edema

Atlantodental Overlap / Lateral Mass Symmetry

Symmetric, aligned

Normal Value

Asymmetry = C1 fracture, Jefferson fracture, or rotation

Cervical Lordosis

Cobb angle ~20–40°

Normal Value

Loss = muscle spasm/trauma; Increased = postural or congenital

Intervertebral Disc Height (all levels)

Uniform, preserved

Normal Value

Narrowing = degenerative disc disease, infection, trauma

Vertebral Body Height

Maintained; Anterior ≈ Posterior

Normal Value

Wedge collapse = fracture, infection, tumor, osteoporosis

Thoracic Kyphosis (Cobb Angle T2–T12)

20–40°

Normal Value

>40° = hyperkyphosis (Scheuermann’s, osteoporosis, trauma)

Lumbar Lordosis (Cobb Angle L1–S1)

40–60°

Normal Value

Decreased = flat back; Increased = hyperlordosis

Lumbosacral Angle (Ferguson’s angle)

30–40°

Normal Value

Abnormal angulation predisposes to spondylolisthesis or pain

Interpedicular Distance (Lumbar AP view)

L1 ~25 mm → L5 ~35 mm

Normal Value

Narrowing = spinal stenosis; Widening = burst fracture, tumor

Spinous Process Alignment

Straight line in AP view

Normal Value

Step-off/deviation = fracture, dislocation, scoliosis

Sacroiliac Joint Symmetry (on LS spine films)

Symmetric, joint space ~2–4 mm

Normal Value

Widening = trauma, infection; narrowing = sacroiliitis, AS

Scoliosis Measurement (Cobb Angle)

<10° normal

Normal Value

≥10° = scoliosis (mild 10–20°, moderate 20–40°, severe >40°)

Vertebral Alignment (Sagittal/Coronal)

Smooth anterior & posterior line continuity

Normal Value

Step deformity = fracture, dislocation, spondylolisthesis

Pars Interarticularis Integrity (Oblique lumbar view)

“Scotty dog” appearance intact

Normal Value

Defect (“collar” on Scotty dog) = spondylolysis

Pedicle Position (AP spine view)

Symmetric, equidistant

Normal Value

Asymmetry = rotation, fracture, destructive lesion (metastasis)

Measurement	Normal Value	Comments
Atlanto-Dens Interval (ADI, Cervical C1–C2)	Adults: <3 mm; Children: <5 mm	Increased = transverse ligament rupture, RA, trauma, Down’s syndrome
Prevertebral Soft Tissue Thickness (Cervical)	C2: <7 mm; C6: <22 mm	Thickening suggests hematoma, abscess, tumor, or edema
Atlantodental Overlap / Lateral Mass Symmetry	Symmetric, aligned	Asymmetry = C1 fracture, Jefferson fracture, or rotation
Cervical Lordosis	Cobb angle ~20–40°	Loss = muscle spasm/trauma; Increased = postural or congenital
Intervertebral Disc Height (all levels)	Uniform, preserved	Narrowing = degenerative disc disease, infection, trauma
Vertebral Body Height	Maintained; Anterior ≈ Posterior	Wedge collapse = fracture, infection, tumor, osteoporosis
Thoracic Kyphosis (Cobb Angle T2–T12)	20–40°	>40° = hyperkyphosis (Scheuermann’s, osteoporosis, trauma)
Lumbar Lordosis (Cobb Angle L1–S1)	40–60°	Decreased = flat back; Increased = hyperlordosis
Lumbosacral Angle (Ferguson’s angle)	30–40°	Abnormal angulation predisposes to spondylolisthesis or pain
Interpedicular Distance (Lumbar AP view)	L1 ~25 mm → L5 ~35 mm	Narrowing = spinal stenosis; Widening = burst fracture, tumor
Spinous Process Alignment	Straight line in AP view	Step-off/deviation = fracture, dislocation, scoliosis
Sacroiliac Joint Symmetry (on LS spine films)	Symmetric, joint space ~2–4 mm	Widening = trauma, infection; narrowing = sacroiliitis, AS
Scoliosis Measurement (Cobb Angle)	<10° normal	≥10° = scoliosis (mild 10–20°, moderate 20–40°, severe >40°)
Vertebral Alignment (Sagittal/Coronal)	Smooth anterior & posterior line continuity	Step deformity = fracture, dislocation, spondylolisthesis
Pars Interarticularis Integrity (Oblique lumbar view)	“Scotty dog” appearance intact	Defect (“collar” on Scotty dog) = spondylolysis
Pedicle Position (AP spine view)	Symmetric, equidistant	Asymmetry = rotation, fracture, destructive lesion (metastasis)