Evaluation of Spinal Alignment

Summary of Key Points

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Spinal alignment assessment includes both sagittal and coronal alignment measurement strategies.
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Coronal plan assessments include interpupullary angle, shoulder tilt angle, and Cobb angle measurements.
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Sagittal plane assessments include chin brow to vertical angle, sagittal Cobb angles, and assessments of balance and spino-pelvic parameters.
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Radiographic assessment of spinal balance and alignement must include the entirety of the spine from occiput to pelvis.
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There are four critical components to treating spinal alignment problems: (1) achieve satisfactory neural element decompression, (2) maintain or restore global spinal alignment to neutral, (3) maintain or restore pelvic alignment to neutral, and (4) maintain or restore regional spinal alignment to neutral.

A note from the editors: Dr. Kuntz died prior to the completion of this chapter. It has been minimally refined, since its quality and message were pristine as is.

Neutral upright spinal alignment (NUSA) in asymptomatic individuals is defined as standing with the knees and hips comfortably extended, the shoulders neutral or flexed, the neck neutral, and the gaze horizontal. The ability to maintain NUSA is intrinsic to the human condition because the species is in part defined by the ability to comfortably stand in a neutral upright position for long periods of time. Many spinal procedures are performed to return the patient to asymptomatic NUSA.

Despite wide variations in “normal” regional spinal alignment in asymptomatic individuals, global neutral upright spinal alignment from the occiput to the pelvis in asymptomatic individuals is maintained in a relatively narrow range for maintenance of horizontal gaze and balance of the spine over the pelvis and femoral heads ( Figs. 4-1 through 4-4 ; Tables 4-1 and 4-2 ). As alignment changes in one region of the spine in asymptomatic individuals, compensatory changes occur in adjacent regional axial skeletal alignment to maintain global spinal alignment. In the coronal plane, the pelvis is relatively fixed so that as a regional spinal scoliosis develops, compensatory scoliotic curves develop (rotating in the opposite direction) above and below the main scoliosis to maintain neutral coronal global spinal alignment. In the sagittal plane, the pelvis may rotate on the femoral heads so that as regional spinal kyphosis develops, the pelvis rotates posteriorly on the femoral heads and compensatory lordotic spinal changes develop above and below main kyphosis to maintain neutral sagittal global spinal alignment. In the sagittal plane, as regional spinal lordosis develops, the pelvis may rotate anteriorly on the femoral heads and compensatory kyphotic spinal changes develop above and below main lordosis to maintain neutral global spinal alignment.

TABLE 4-1

Pooled Estimates of the Mean and Variance of the Neutral Upright Coronal Spinal Angles and Displacements from the Occiput to the Pelvis

Charles Kuntz IV Neutral Upright Coronal Spinal Alignment Guide: Asymptomatic Individuals
	Neutral Values
	Mean (1SD)
	adolescent	adult	geriatric
	10–18 years	> 18 years	> 60 years
R egional S pinal A lignment
Occipitocervical Junction Angle
O-C2 apex		—
Cervical Angle ^o
C2-3 disc–C6-7 disc apex		—
Cervicothoracic Junction Angles
C7-T1 apex		—
Proximal Thoracic Angle
T1-2 disc–T5 Apex	< 15 *	< 20 *	< 25–30 *
Main Thoracic Angle
T5-6 disc–T11-12 disc apex	< 15 *	< 20 *	< 25–30
Thoracolumbar Angle
T12-L1 apex	< 15 *	< 20 *	< 25–30
Lumbar Angle
L1-2 disc–L4-5 disc apex	< 15 *	< 20 *	< 25–30
Lumbosacral Junction Angle
L5-S1 apex		—
ShTA		1 (2)
ATI		—
AVT (mm)		—
AVR		< 5–10 *
P elvic A lignment
Pelvic obliquity (PO)		< 8 *
Leg length discrepancy (LLD) (mm)		6 (4)
G lobal S pinal A lignment
Head Tilt Angle
IPA		0 (1)
Coronal Spinal Balance (mm)
TT-S1 CVA		—
C7-S1 CVA		+4 (12)