Metrics in spinal deformity

Spine Conference: Adult Scoliosis

Shashank Gandhi, MD4/11/14

Outline• Adult Sciolosis• Spinopelvic parameters• Case• Surgimap Spine

Adult Idiopathic Scoliosis• Pre-existing adolescent idiopathic scoliosis• Slow increase in curvature• Curves increase 0.5-2o per year• Adolescent curves <30o unlikely to

progress significantly into adulthood• Curves >50o likely to worsen

• Requires monitoring

ASA 1

• smaller flexible curves • 18-30 years old• Posture and cosmetic concerns• Pain can be an issue in

unbalanced curves• reducibility in abnormal posture

and Cobb angle

ASA 2

• larger more rigid curves • adults 30-40 years old• Pain and posture equally

issues• Pain an issue even in balanced

curves• early degenerative changes• Intervention could stop

progression to ASA 3

ASA 3

• large, rigid curves • older adults 40+• Pain is the primary concern• Moderate to severe

degenerative changes • Most commonly lumbar curves• No previous history of scoliosis

could indicate degenerative de novo scoliosis

Adult Degenerative (de novo) Scoliosis

• Large, rigid curves• >50 years old• Due to degenerative instability• Loss of lumbar lordosis• Settling of discs lead to positive

sagittal balance• Pain is primary concern

Prevalence of Adult Scoliosis in Back Pain

Perennou et al• 671 LBP patients:

• 7.5% with scoliosis• Prevalence increased with

age:• 2% before 45 years (ASA)• 15% after 60 years (DDS)

Robin et al• 554 LBP patients

• Aged 50 to 84 • 30% scoliosis >10°

• At 5 year follow up • 40% scoliosis >10°• Additional 10%

Progression of Adult Curves

Spinal Degeneration

Soft tissue integrity lost

Functional unit instability

increased

ScoliosisProgression

Boney adaptation

Post-Surgical Deformity

• Post-laminectomy scoliosis or kyphosis• Post-surgical instability or pseudoarthrosis• Adjacent level disease• “Flat-back syndrome”• Traumatic

Presentation • AIS – rarely have pain• Low back pain & stiffness most

common – 85% • Radicular pain• Neurogenic claudication• May lean forward

– open narrowed spinal canal– secondary to loss of lumbar

lordosis• Compensatory maneuvers for upright

posture– Bend at hips & knees

• Strain on muscles causing early fatigue & pain

• Dubousset - Cone of Balance

Spinopelvic Parameters• Pelvic parameters• Spinal (regional) curves• Global alignment

NonOperative Management• Pain control• PT• Orthosis (no evidence of slowing progression)

Surgical Indications• Unrelieved pain• Progressive deformity• Neurological deficits• Cosmesis

Differences in Treatment in AIS and Fixed Adult Scoliosis • Curves are generally stiff• Higher risk with a higher complications rate in

adults (high as 80%)• More invasive surgical procedure is needed

(VCR, osteotomies, Anterior release, etc.)• Goals

• Correction of 3D deformity• Restoration of balance• Fusing minimal number of levels necessary

• Stop curvature progression• Allowing residual spinal mobility

Pelvic Parameters PI = PT + SS• Pelvic Incidence (PI) • Pelvic Tilt (PT)• Sacral Slope (SS)

• PT & SS inversely change• Pelvic parameters affect entire sagittal

alignment• Sacral plateau & femoral heads affect

thoraco-lumbar load transfer

Pelvic Incidence• Morphological parameter• Anatomical char of pelvis• Defines lumbar alignment• No variation over time in

adults• Mimics vector of load

transmitted to sacral plateau

• Avg PI = 55o +/- 10o

Pelvic Tilt• Positional parameter• Spatial orientation of pelvis• Compensatory mechanisms• Normal ~13o +/- 6o

• goal <20o

• As PT inc the center of gravity moves more posterior to femoral heads

Sacral Slope

• Determines position of lumbar spine

• Maximal retroversion at 00

Large PI more lumbar lordosis

Global Shape

• Curves proportional to teach other if:• Thoracic kyphosis (TK)

• 20-40o

• Dependent on LL & C7 position• Lumbar lordosis (LL)

• 30-80o

• 20-40o > TK

• Dependent on SS (SS+20)• Stability in bipedal position

• Sagittal vertical axis (SVA)• Goal SVA <5cm

Types of Lumbar Lordosis

Sacral Morphology & Lordosis• Low PI

– Low sacral slope– Low pelvic tilt– Vertical sacrum– Flat lumbar lordosis– Low shear stress at LS jxn– Low risk of

spondylolisthesis

Sacral Morphology & Lordosis• Larger PI

– High SS– High PT– Increased lumbar lordosis– High risk of spondylolisthesis– High shear stress at JS jxn– Horizontal sacrum– High possibility of

retroversion

Goal: LL = PI (+/- 9o)

Compensatory Pelvic TiltHip Retroversion can allow C7PL to be in balance

Large SVA, No PT

Mod SVA, Mod PT

No SVA, Large PT

Pelvic & Knee Compensation

• Retroversion (inc PT) can compensate for kyphosis

• Severe kyphosis causes hip extension – limiting PT

• Compensate with knee flexion

• 298 patients• correlate radiographic

measures with patient-based quality of life

Positive sagittal balance• Greater pain• Lower physical function• Poor self image• Poor social function

“Correlation of Radiographic Parameters and Clinical Symptoms in Adult Scoliosis” - Glassman, et al. Spine 2003

• Coronal shift > 4 cm • Poorer function • Greater pain

• + SB predicts clinical symptoms

• Thoracolumbar and lumbar curves have worse outcomes than thoracic curves.

• Significant coronal imbalance was associated with pain and dysfunction.

“Correlation of Radiographic Parameters and Clinical Symptoms in Adult Scoliosis” - Glassman, et al. Spine 2003

“normal” T1-Tilt -9-7o

Alignment Objectives• Quality of life driven goals:

• SVA <5cm• T1 Tilt <0o

• PT <25o

• Proportional SB: LL = PI +/- 9o

Case: BM• 56y/o M p/w more than 2 year of low

back pain rad to LEs. 2012 L2 hemilaminectomy for LBP to LE. Failed trial of spinal cord stimulator 1/2013. Early fatiguing and leaning forward

• PMH: HTN, HLD, IBS, OSA• Meds: Dilaudid, Valium, Lexapro

• Neuro: Intact; strength 5/5 throughout

2/2012

3/2014

Case: BM• Surgical options?

- Levels- Fusion in situ- Multi level ponte osteotomies- PSO- Asymmetric PSO

Case: BM• Stage 1: T8-L4 Screws• Stage 2: L2 PSO, placement of rods

Post-Op