A comprehensive clinical impact classification of Adult Scoliosis

• F. Schwab• K. Bridwell• S. Berven• J-P Farcy • S. Glassman• J. Harrast• W. Horton• M. Ferguson

Spine Deformity Study Group, San Diego 2005

Why a classification ?

• Must develop a common language:– exchange of information– comparison of data

• Correlation with clinical impact– treatment algorithms– surgical guidelines

Scoliosis

• Prevalence– AIS 2-4% of screened pediatric population

– Adult >60% of screened elderly population

Demographic :Life expectancy, birth rates….Significant growth of aging population segment

Adult Scoliosis Classification:

• Chicago 2002

• Arizona 2003

• Chicago 2003

• Miami 2004

IMASTWorldspineSRSNASS

Adult Scoliosis Classification:Clinical impact

• Significant – Spondylolisthesis– Frontal plane subluxation– Lumbar lordosis– Thoracolumbar alignment– Apical level +/-

– Global alignment

• Not significant– Coronal Cobb

– AISA vs DDS

– Age

The Classification

• Simple– Basic structure 3 parameters

• Lumbar lordosis T12-S1

• Maximal intervertebral subluxation (frontal/sagittal)

• Apical level of deformity (lumbar dominant)

Selected for high clinical impact: SRS-22, ODI

The Classification• Apical Level…curve Type

– Type I : thoracic-only scoliosis – Type II: upper thoracic major curve, apex T4-8

– (with a thoracolumbar or lumbar curve)

– Type III: lower thoracic major curve, apex T9-T10– (with thoracolumbar or lumbar curve)

– Type IV: thoracolumbar major curve, apex T11-L1– (with any other minor curve)

– Type V: lumbar major curve, apex L2-L4 – (with any other minor curve)

The Classification

• Lordosis Modifier (T12-S1)

A: marked lordosis >400

B: moderate lordosis 0-400

C: no lordosis present Cobb >00

The Classification

• Subluxation modifier– Maximal intervertebral subluxation

• Frontal or sagittal plane

0 : no subluxation

+ : subluxation 1-6mm

++: subluxation >7mm

Intra-, inter-observer variability study• 20 cases

• full-length films• AP and Lateral

• 13 one-time readers• 6 repeat readers

Adult Scoliosis Classification

Adult Scoliosis ClassificationInter-observer analysis

Paired Comparaisons

Kappa%

AgreementPaired

ComparaisonsKappa

% Agreement

Paired Comparaisons

Kappa%

Agreement

1560 0.63 74% 1560 0.90 95% 1560 0.93 95%

Curve Type Lordosis Modifier Subluxation ModifierInter-Rater Reliability

Disagreements on• thoracic levels (Type II, III)• thoracolumbar vs. lumbar

Adult Scoliosis ClassificationIntra-observer analysis

Paired Comparaisons

Kappa%

AgreementPaired

ComparaisonsKappa

% Agreement

Paired Comparaisons

Kappa%

Agreement

Reader 1 20 0.92 95% 20 1.00 100% 20 0.92 95%Reader 2 20 0.84 90% 20 1.00 100% 20 1.00 100%Reader 3 20 0.92 95% 20 0.90 95% 20 1.00 100%Reader 4 20 0.63 75% 20 1.00 100% 20 1.00 100%Reader 5 20 0.85 90% 20 0.90 95% 20 1.00 100%Reader 10 20 1.00 100% 20 1.00 100% 20 1.00 100%Overall 120 0.86 87% 120 0.97 98% 120 0.99 99%

Curve Type Lordosis Modifier Subluxation Modifier

SDSG data set 1/05

patients 947female 814male 131n/a 2

Average+/- stand. dev. age: 48 +/- 18 yearsAverage+/- stand. dev. coronal Cobb: 46 +/- 19 degreesAverage+/- stand. dev. Sagittal Cobb (T12-S1): -46 +/- 25 degrees

Upper thoracic (apex T4-T7)patients 52

Lower thoracic (apex T8-T10)patients 273

Thoracolumbar (apex T11-L1)patients 343

Lumbar (apex L2-L4)patients 279

Primary curve apex

Adult Scoliosis Classification

• Type I curves (thoracic only)– 17 subjects (12F, 5 M)– Coronal Cobb mean 43 (SD17)– Mean SRS pain 67 (SD 19)– Mean SRS function 66 (SD 23)– Mean ODI 27 (SD 20)– Surgical rate 41%

Adult Scoliosis Classification

• Type II curves (upper thoracic major, apex T4-7)– 48 subjects (43F, 5 M)– Coronal Cobb mean 47 (SD 22)– Mean SRS pain 65 (SD 20)– Mean SRS function 69 (SD 18)– Mean ODI 28 (SD 22)– Surgical rate 35%

Adult Scoliosis Classification

• Type III curves (lower thoracic major, apex T8-10)– 260 subjects (215 F, 44 M)– Coronal Cobb mean 50 (SD 20)– Mean SRS pain 65 (SD 21)– Mean SRS function 72 (SD 17)– Mean ODI 24 (SD 20)– Surgical rate 39%

Adult Scoliosis Classification

• Type IV curves (thoracolumbar major apex T11-L1)– 343 subjects (302 F, 40 M)– Coronal Cobb mean 47 (SD 19)– Mean SRS pain 60 (SD 19)– Mean SRS function 65 (SD 17)– Mean ODI 31 (SD 19)– Surgical rate 48%

Adult Scoliosis Classification

• Type V curves (lumbar major, apex L2-L4)– 279 subjects (242 F, 37 M)– Coronal Cobb mean 42 (SD 19)– Mean SRS pain 61 (SD 19)– Mean SRS function 63 (SD 17)– Mean ODI 34 (SD 19)– Surgical rate 37%

Adult Scoliosis Classification

• Lordosis Modifier (T12-S1)

Sagittal Cobb <-40: n=557Sagittal Cobb -40 to <0: n=261Sagittal Cobb >=0: n=44Sagittal Cobb n/a: n=85

ABC

• Subluxation Modifier (maximal, in mm)

Adult Scoliosis Classification

0 Maximal Frontal or Sagittal Subluxation None: n= 526"+" Maximal Frontal or Sagittal Subluxation 1 to 6 mm: n= 109"++" Maximal Frontal or Sagittal Subluxation >= 7 mm: n= 299

Adult Scoliosis Classification

Oswestry SRS Function SRS Pain Mean SD Mean SD Mean SD

p = 0.002 p < 0.001 p = 0.007Lordosis modifier A (< -40) 27 19 69 17 65 20

Lordosis modifier C ( >= 0) 37 16 57 15 56 17

Oswestry SRS Function SRS Pain Mean SD Mean SD Mean SD

p < 0.001 p < 0.001 p < 0.001Subluxation Modifier 0 27 20 68 18 64 20

Subluxation Modifier ++ 34 18 63 16 58 19

Adult Scoliosis

• A valid Classification – Simple approach possible

• High clinical impact

• Frontal and sagittal plane considerations

• Validated through largest database available

– Reliable system• Intra- and inter-observer

Adult Scoliosis ClassificationThe Classification – clinical impact

ApexLumbar Lordosis Intervertebral subluxation

Do we need descriptive parameters ?exact number/patterns of curvesCobb anglesLevels of instability, DJD

Other parameters ?

Adult Scoliosis Classification

• Next Steps:– Refine group definitions– Combine with Surgical Classification

• T-L junction

• L-S junction

– Longitudinal analysis

Ongoing review as database grows