1) Description of Measurement

The AO Spine Adult Spinal Deformity (ASD) Profile is a consensus-derived, multimodal framework intended to holistically describe adult spinal deformity beyond radiographs alone. Rather than functioning as a purely morphologic curve-type system, it categorizes patients across four major domains:

• General Health Status – demographics, frailty, comorbidities, social support.

• Spine-Specific Health – pain, disability, neurologic impairment.

• Imaging – coronal and sagittal alignment parameters and MRI-based neural compression.

• Type of Deformity (Etiology) – deformity pattern and pathophysiology.

The classification emphasizes:

• Deformity Type & Location (thoracic, thoracolumbar, lumbar; primary vs secondary degenerative vs idiopathic origin).

• Neurologic Impact, distinguishing radiographic compression from clinically relevant deficits (radicular pain, motor weakness, sensory loss).

• Integration of coronal and sagittal plane deformity with compensatory mechanisms.

2) Instructions to Measure

A. Radiographic Assessment (Standing PA & Lateral X-ray)

1. Identify deformity location:

• Thoracic (T2–T11)

• Thoracolumbar (T12–L1)

• Lumbar (L2–L4)

2. Determine coronal curve type and magnitude:

• Measure major Cobb angle (°).

• Record coronal balance using C7 plumb line (cm).

3. Measure sagittal parameters:

• Sagittal Vertical Axis (SVA, cm)

• Pelvic Incidence (PI, °)

• Pelvic Tilt (PT, °)

• Lumbar Lordosis (LL, °)

• Note presence of compensated spine (thoracic, thoracolumbar, lumbar, pelvic).

4. Identify etiologic deformity type (Aebi-based):

• Type I – Primary degenerative (“de novo”).

• Type II – Adult idiopathic scoliosis (AdIS).

• Type III – Secondary degenerative (spine-related or neuromuscular).

B. Neurologic Assessment (MRI)

1. Evaluate for neural compression (central canal stenosis, foraminal stenosis).

2. Document clinical relevance:

• Radicular pain: yes/no, dermatomal vs non-specific.

• Motor weakness: yes/no; clinically relevant or not.

• Sensory loss: yes/no; clinically relevant or not.

3) Normal vs. Pathologic Ranges

• Coronal Cobb angle: <10° (normal); ≥ 10° (scoliosis)

• Sagittal Vertical Axis (SVA): < 4 cm (normal); ≥ 5 cm positive sagittal imbalance

• Pelvic Tilt (PT): < 20° (normal); ≥ 25° (pelvic compensation)

• PI-LL mismatch: < 10° (normal); ≥ 10-20° (mismatch)

• Neural compression: Absent (normal); central/foraminal stenosis (pathologic)

• Neurological deficit: None (normal); radicular pain, weakness, sensory loss, (clinically relevant)

4) Important References

Naresh-Babu J, Kwan KYH, Wu Y, et al; AO Spine Knowledge Forum Deformity. AO Spine Adult Spinal Deformity Patient Profile: A Paradigm Shift in Comprehensive Patient Evaluation in Order to Optimize Treatment and Improve Patient Care. Global Spine J. 2023 Jul;13(6):1490-1501. doi: 10.1177/21925682211037935.

Schwab F, Ungar B, Blondel B, et al. Scoliosis Research Society-Schwab adult spinal deformity classification: a validation study. Spine (Phila Pa 1976). 2012 May 20;37(12):1077-82. doi: 10.1097/BRS.0b013e31823e15e2.

Aebi M. The adult scoliosis. Eur Spine J. 2005 Dec;14(10):925-48. doi: 10.1007/s00586-005-1053-9.

5) Other info....

This AO Spine system is not a treatment-directive algorithm, but a structured patient profiling framework integrating deformity morphology with neurologic and health-status drivers.

Neurologic impairment is recorded using clinical relevance rather than imaging severity alone.

Deformity etiology strongly influences management strategy:

• Type I (de novo degenerative) – often short-segment pathology with significant stenosis.

• Type II (AdIS) – large structural curves with coronal and sagittal imbalance.

• Type III (secondary) – post-traumatic, iatrogenic, or neuromuscular causes with complex compensation.

This system provides a foundation for consistent ASD documentation and facilitates development of future outcome-driven, data-adaptive classifications.