Adult spinal deformity

Question 1

Define adult spinal deformity?

Answer 1

• Adult spinal deformity= a lateral spinal curve >10^o in a skeletally mature individual

Question 2

What is the epidemiology of adult spinal deformity?

Answer 2

• Males = females
• Mean age is 60 years
• up to 90% have symptoms related to stenosis

Question 3

What is the pathoanatomy of adult spinal deformity?

Answer 3

• Degenerative sciolosis results from Asymmetric disc degneration and or facet degeneration
• may occur in sagittal ( kyphosis/lordosis) or coronal plane ( scoilosis)
• risk factors for sagittal plane deformity
  
  • osteoporosis
  • preexisitng sciolosis
  • degenerative disc disease
  • itraogenic scoliosis

Question 4

What are the signs and symptoms of adult spinal deformity?

Answer 4

Symptoms

• back and leg pain - 61%
• neurogenic claudication- pain LL and buttocks
  
  • _no relief with sitting/forward flexion _
  • caused by spinal stenosis on concave side
• ​Radicular leg pain and weakness
  
  • ​foraminal and lateral recess stenosis

Signs

• Muscle weakness
• prominence thorac when bending forwards
• Neuro exam to exclude any nerve compression

Question 5

Name the types of adult spinal deformity?

Answer 5

• Idiopathic ASD
  
  • residual
  • the untreated adolescent idiopathic sciolosis post skeletal maturity
• De novo ASD- progressive degenerative changes in spine
  
  • degenerative
  • Iatrogenic
  • Paralytic
  • Post traumatic

Question 6

what are the differences between idopathic ASD and De novo ADS?

Answer 6

Idiopathic

• larger more predictable curves
• mutliple levels
• normally thoracic spine

De novo

• smaller less predcitable curves
• fewer vertebral segements
• normally lumbar spine

Question 7

What is the progression of the curve?

Answer 7

• 1.0^o per pa for thoracic curve >50^o
• 0.5^{<span>o</span>} for thoracolumbar
• 0.24^o for lumbar curves
• Curves <30^o rarely progress
• Curves >50^o commonly progess

progession all due to location

• thoracic curve progress more rapid than lumbar, thoracolumbar adn double major curves
• loss of normal sagittal balance ( thoracic kyphosis, lumbar lordosis) common
• risks- osteoporosis, preexisiting scoliosis, itatrogenic instability, degenerative disc disease

Question 8

What iinvestigations are useful in adult spinal deformity?

Answer 8

xrays

• ap and lateral
• measure cobb angle - magnitue of curve
• C7 plumb line
• (C7 ) centre sacral vertical line- coronal malignment
• bending views- curve flexibility & possibility of correctio with surgical intervention

MRI

• identify- Central canal stenosis, facet hypertrophy, pedicular enlargement, formainal encroachment & disc degeneration

CT myeolgraphy

• useful as MRI because rotational deformity and bony anatomy better on CT

Question 9

What are the tx for adult spinal deformity?

Answer 9

Non operative

• mainstay of tx in whom surgery CI
• Coronal curves <30^o rarely progress
• Core strengthening programs- low impact walking, swimming, cycling and selected weight lifting
• NSAIDS
• Tricyclic antidepressants - with sleep distrubance
• corticosteriod injections or selective nerve root blocks
  
  • diagnostic- to validate foraminal compression
  • therapeutic
• bracing coupled with continuous exercise

Question 10

What are the indications for surgical tx?

Answer 10

• Coronal angle >50^o
• sagittal imbalance
• curve progression
• intractable back pain or radicular pain that has failed nonsurgical efforts
• cosmesis (controversial)
• cardiopulmonary decline
  • thoracic curves >60deg affect pulmonary function tests
  • thoracic curves >90deg affect mortality

Question 11

what is the surgical tx of ASD?

Answer 11

• Posterior curve correction and instrumented fusion
  
  • thoracic curves >50^o
  • Most double curves >50 o
• Combined anterior and posterior fusion
  
  • isolated thoraolumbar curves
  • islocated lumbar curves
  • extreme rigifity requiring anterior release

Question 12

What are the surgical tx for adult spinal deformity?

Answer 12

• Correction often requires combined ant/post surgeries either staged or preformed same day
• Longer surgeries, higher complication risks, more medial stress pt.careful pt selection and preop planning

Thoracic curves- arthrodesis

• limited thoracic curves approached posteriorly
• exceptions are extremely rigid- may need release from anterior first
• only thoracic deformity tx-> compromise lumbar spine
• start arthrodesis high T2/T3

Isolated thoracolumbar/lumbar curves

• decompression, instrumentation & arthrodesis of deformity, correction of curve
• Posterior or combined ant/post approach

2 or more structural curves

• multiple curvex can be corrected posteriorly
• proximal extend to neutral/horzontal curve

Question 13

What are the goals of surgery?

Answer 13

• Achievement of spinal balance
  
  • correct Sagittal vertical axis to within 5cm of neutral
  • ensure pelvic tilt is <20 degrees
  • ensure lumbar lordosis is within 9 degrees of pelvic incidence
• relief of pain
• solid arthrodesis

Question 14

What are the features with extending arthrodesis to S1?

Answer 14

• Contraversial
• Key consideration is any instability of L5-S1 segement to include spondylolisthesis or previous laminectomy
• only indicated if no pathology at L5-S1- otherwise need to extend to S1

Advantages

• L5-S1 fusion extends stability of long fusion construct
• Anterior column support becomes more important and is more efficiently gained thru an anterior approach, allowing for ant release and better deformity correction
• stopping at L5 may -> painful disc pathology below fusion in future years
• Pts with normal sacral inclination and normal C7 plumb line have the lowest incidence of L5-S1 disc degeneration

Disadvantage

• Increase peudoarthrosis rate
• increase surgical time
• increase reoperation rates
• Increase rate of sacral insufficiency fractures
• alters gait post op

Question 15

When is sacrum fusion required?

Answer 15

• If any pathology at L5-S1
  
  • Spondolythesis, spondylolysis
  • same advantage & disadvanatges as L5/S1 fusion

Question 16

when is sacropelvic fusions required?

Answer 16

• If sacrum involved in fusion with more than 3 vertebra
• uses iliac bolts

advantage

• increased stability of long fusion construct
• increases success of lumbosacral fusion

disadvantage

• prominent hardware

Question 17

When are osteotomies required?

Answer 17

• To regain sagittal balance in severly angulated deformities
• 30^o or more can be gained thru different types of osteotomies
  
  • pedicle subraction
  • Smith- peterson techique​ - see pic
  • more correction in lumbar than thoracic spine
• Larger ooperations with higher complication rates, more blood loss, grater technical fitnesses

Question 18

Describe how you would meaure the cobb angle?

Answer 18

• locate superior vertebra-superior surface tilts towards side of concavity
• locate inferior vertebra- inferior suface tilts towards concavity
• erect perpendicular 90⁰ line from superior edge of superior vertebra and inferior edge of inferior vertebra
• where cross = cobbs angle
• normal 10-20 ^o
• 20-40 brace
• 40^o > surgery

Question 19

What is sagittal balance?

Answer 19

• Due to normal cervical lordosis, thoracic kyphosis and lumbar lordosis
• normal alignment
  
  • vertical axis runs from centre C2 to ant border of T7 to middle of T12/L1 disc, posterior to L3 and crosses post superior corner of sacrum
  • radiographic plump line dropped form C7 to superior-postrior corner of S1
• most reliable radiographic predictor of clinical health status in adults with spinal deformity

Question 20

What is negative sagittal balance?

What is positive sagittal balance?

Answer 20

• Axis is posterior to sacrum
• occurs in pt with lumbar hyperlordosis
• Axis is anterior to sacrum
• occurs in pts with hp flexion contracture or flat-back syndrome

Question 21

what is the prognoiss of adult spinal deformity?

Answer 21

• _Worse prognosis _
  
  • symptoms progress to side of curve convexity
  • sagittal plane imbalance

Question 22

What are the indications for a vertebral column resection- vertebrectomy?

Answer 22

• Severe sagittal imbalance (provides more correction than PSO) requiring correction of up to 45deg
• rigid angular thoracic spine kyphosis, such as associated with tumor, fracture or infection
• severe rigid scoliosis
• congenital kyphosis
• hemivertebrae resection in thoracic/lumbar spines

Question 23

When would a anterior approach be required?

Answer 23

• Large curves >70o
• rigid curves
• isolated lumbar/thoracolumbar
• anterior interbody fusion at L5/S1 when fusing to sacrum
• Anterior release and fusion usually combined with posterior instrumentation and fusion at smae day or staged
  
  • longer surgery
  • higher complications rate
  • more medically stressful
  • adv- helps restore sagittal and coronal balance
  • more stability L5-S1 with long fusion construct

Question 24

what are the complications?

Answer 24

• 10% irreversible major complications- neurological, DVT?PE, cardiac effecting overal outcome
• venous thromboelmbolism-> poor outcome
• Pseudoarthrosis
  
  • ​most common in post spinal fusion-15%
  • common L5-S1
  • risks; age >55, smoking, positive sagittal balance, hip arthritis,kyphosis >20o,thoracoabdominal approach
• ​Infection
  
  • ​UTI
• ​Neurological compromise
  
  • ​0.5-5%
• ​PE
  
  • ​1-20%
• ​Instrumental problems

Question 25

How do you masure pelvic tilt?

Answer 25

• draw aline along sacrum
• perpendicular line to this
• vertical line from obtruator foramen
• intersection of line = angle

Question 26

How do you measure the sacral angle?

Answer 26

• line along sacral body
• horizontal line parallel to L5 which transects this
• angle formed is sacral angle/slope

Question 27

How do you measure the pelvic inclination?

Answer 27

• Pelvic incidence defined as the angle between the perpendicular to the sacral plate at its midpoint and the line connecting this point to the femoral heads axis.
• “Pelvic Incidence = Pelvic Tilt + Sacral Slope.