Scoliosis
Lateral curvature of the spine of 10o or more with associated vertebral rotation (SRS)
Incidence
Screening: 1.3 - 1.8 per 1000
Male : Female = 3.5:1 but more females with larger curves (more than20o the ratio goes to1:5)
Male sex is a good prognostic factor
Girls are more commonly affected with 2 - 3% at the age of 16 having a scoliosis more than 10o, 0.5% more than 20o and 0.2 - 0.3% more than 30o
Classification
Mobile:
(SRS Non structural) No structural abnormality, vertebrae not rotated and the curve is always reversible
May be
- postural
- compensatory (eg leg length discrepancy)
sciatic (due to nerve root irritation or compression)
- Fixed:
- (SRS Structural) Always associated with vertebral rotation and does not disappear with changes in posture (eg bending forward)
Secondary curves develop to compensate for the primary deformity which may also become fixed
Aetiology: (Structural)
Idiopathic(accounts for the majority of curves ~ 80%)
- Infantile:
- Less than 3 years
Male more than Female and ~ 90% are thoracic curves convex to the left
85% resolve spontaneously- these have curves less than 35 deg
15% progress- these have
1. curve more than 35 deg
2. RVAD more than 20 deg
treat those who progress
- Juvenile:
- 4 - 9 years of age with similar characteristics to the adolescent group but greater likelihood of progression and the need for operation
- Adolescent:
- Older than 10 years
Most common type with 90% being female
Primary thoracic curves with 90% being convex to the right
Primary lumbar curves are convex to the left in 80% of cases
- Adult:
- spinal curvature existing after termination of skeletal growth or maturity
Osteopathic or congenital
Failure of formation
- partial unilateral (wedge vertebra)
complete unilateral (hemivertebra)
fully segmented
semisegmented
unsegmented
- Failure of segmentation
- unilateral ( unilat unsegmented bar)
bilateral ( bloc vertebra)
- Mixed: Assoc with neural tissue defect
- myelomeningocoele
meningocoele
spinal dysraphism eg diastematomyelia
Seldom hereditary, most are sporadic, apparently arising from defects in the foetal development process at the 5th to 7th week
only about 25% are non progressive
Neuropathic
- UMN lesion
- cerebral palsy
spinocerebellar degeneration Freidrichs ataxia
CMT
Roussy- Levy
syringomyelia
spinal cord tumour
spinal cord trauma
- LMN lesion
- polio
spinal muscular atrophy-autosomal recessive - loss of ant horn cells
3 types:
- Werdnig-Hoffmann- appears before 6/12 poor prognosis
- Chronic Werdnig-Hoffman appears 6/12-5yo
- Kugelberg-Welander appears bw 2 - 17 yo
bracing not successful- fuse if curve more than 40 deg
Dysautonomia
Result in long 'C' curve if symmetrical weakness, shorter curves or double major curves if weakness is asymmetrical
Polio usually flexible and CP and Spina bifida usually rigid
Myopathic
Arthrogryposis
muscular dystrophy Duchennes lose ability to walk by ~ 12
once in wheelchair- 50-80% scoliosis curve progressive, bracing poorly tolerated, fuse if more than 35 deg
Limb girdle
Fascioscapulohumeral
congenital hypotonia
Myotonia dystrophica
Mesenchymal Disorders
Marfans
Ehlers Danlos syndrome
Homocystinuria
Metabolic
- Rickets
- juvenile osteoporosis
Osteogenesis imperfecta
Osteochondrodystrophies
Achondroplasia
spondyloepiphyseal dysplasia
Mucopolysaccharidoses
Neurofibromatosis
Miscellaneous
trauma -#or dislocation ( nonparalytic)
tumour benign or malignant
thoracogenic post thoracoplasty or thoracotomy
hysterical
extra-spinal contractures (eg burns, post empyema)
infection
Classification: (King)- idiopathic
ref: King etal The selection of fusion levels in Thoracic Idiopathic Scoliosis JBJS 65A: 1302-1313, 1983
- Type I:
- 'S' shaped curve with both curves crossing the midline and the lumbar curve being of greater magnitude on the standing X-Ray (~13%)
- Type II:
- 'S' shaped curve with the thoracic curve being greater than the lumbar and both still cross the midline (~33%)
- Type III:
- Thoracic curve in which the lumbar curve does not cross the midline (~33%)
- Type IV:
- Long thoracic curve with L5 over the sacrum but L4 tilts into the curve (~9%)
- Type V:
- Double thoracic curve
Clinically
History
Deformity usually leads to presentation
Pain no more frequent than back pain in the general population
- skin
- abnormalities in spine area- hairy spots, lipomas
cafe au lait spots
area of curve
shoulder elevation on concave side ( also breast)
reduced waist on concave side
rib hump on convex side
loin hump on concave side
is curve balanced- plumb line occiput to sacrum
- Leg length
forward bending
- rib hump accentuated ( nonstructural scoliosis abolished )
- measure rib hump
- in cm or deg from horizontal
in forward bending away from the examiner persistent deviation to one side suggests cord or cauda equina - irritation- need to rule out tumour eg MRI
- Neurological examination
- sensory
motor
reflex
tension signs
- Other
- skin- elasticity
hips
feet
hands - hypermobility
palate high arch in Marfans
Look for associated anomalies in congenital scoliosis (eg, reno-genital 25%, dysraphism 20%, heart deformities, Sprengel's shoulder and Klippel-Feil, absent thumb, anal agenises, tracheo-oesophageal fistula etc
X-Rays
Measurement of curvature (Cobb technique)
Standing XR used for measurement
Select the end vertebrae of the curve ( the most tilted from the horizontal)
A line is drawn along the upper end plate of the upper vertebra and another along the lower end plate of the lower vertebra.
Perpendiculars are erected from these - the angle bw the perpendiculars is the angle of the curve
Once the end vertebra have been established measurement should always be from the same vertebrae- supine and bending films included
When a double curve is present ie 2 structural curves both must be measured - one vertebra will be the end vertebra for one curve and the beginning of the other curve= the transitional vertebra
For measuring flexibility -supine maximum voluntary bending films are good for non paralytic problems when curves are less than 80 deg, traction films for paralytic problems or for curves more than 80
The apex vertebrae is the one with the greatest degree of rotation
The major curve is the largest curve and the one with the greatest degree of rotation
Direction of the curve is determined by its convex side
- Rissers sign:
- Divide the iliac crest into quarters
no ossification of iliac apophysis = Risser 1
complete ossification = Risser 4
fusion with wing = Risser 5
Indicates skeletal maturity and takes about 12 - 18 months to become complete after Risser 1 (complete ossification occurs at about 14 in girls and 16 in boys)
Vertebral ring apophysis on lateral X-Ray of spine in lumbar region is the most reliable index of vertebral maturity
Rib-vertebral angle difference (Mehta)
the difference in the angle the rib meets the spine at the apex of the curve- if the angle is more than 20 deg the curve is likely to progress
- Other Investigations
- CT
MRI
Pulmonary function testing
Natural history
- Nilsonne and Lundgren
- Long term prognosis in idiopathic scoliosis Acta Orthop Scand 39: 456, 1968
- 113 pts , 50 yr FU
- twice expected mortality rate for age
-47% disability pensions (30% for spinal deformity)
- 90% had symptoms of bad back
- Ponseti and Friedman
- Prognosis in Idiopathic Scoliosis JBJS 32A: 381, 1950
- most curves stable after skeletal maturity
- thoracic curves
- more than 60 deg increase at 1 deg / yr ( av 28 deg at 24 yrs)
less than 60 deg increase at less than 1/2 deg / yr (av 9 deg at 24 yrs)
- lumbar curves
- more than 30 deg increase at 3/4 deg / yr (av 18 deg at 24 yrs)
less than 30 deg did not progress
vital capacity reduced in curve more than 60 deg- early death from resp failure is likely in pts with thoracic curves more than 60 deg
Pathogenesis
Genetic factors probably multi factorial
? Growth factors but no change in growth increments and spinal dimensions of vertebral bodies involved in the curve compared to those outside the curve
Electromyographic factors have been implemented but these have been shown to be secondary to the deformity
Ultrastructural changes in multifidus also are secondary to the curve
Biochemical factors with differences in the glycosaminoglycans, Type I and II collagen and acid phosphatase may be primary or secondary
Treatment
Idiopathic
Infantile
treat those who progress
- Serial casting followed by Milwaukee brace- usually the brace manages the curve successfully for many years. Continue bracing until curve is maximally or permanently corrected or until curve progresses in brace
- Instrumentation without fusion when progresses despite all nonop measures - aim to delay fusion until 12 in girls and 14 in boys
Juvenile
different from infantile in that curves do not resolve spontaneously
treat those more than 20 deg and less than 60 deg with Milwaukee brace, need to brace until end of growth. If progressive despite bracing, instrument without fusion eg Harrington rod lengthened or replaced every 6 mths, fuse at 12 in girls , 14 in boys
Adolescent
less than 20 deg no treatment - observe
20-29 deg treat if progresses- Milwaukee brace
30-45 deg treat immed with Milwaukee brace
Curves more than 45 deg are less amenable to treatment with bracing- thus start brace treatment on a trial basis and if have not achieved at least 30% improvement within 6 mths then proceed to surgery. Childen with Risser of 4 prior to treatment are not braced because of their skeletal maturity
Bracing
- Indications
- more than20 deg curve with evidence of at least 5 deg progression
skeletally immature
Risser 3 or less
premenarchal or less than 6 mths post
cooperative pt
- Contraindications
- curves more than45 deg
skeletally mature- Risser 4
poor cosmesis
thoracic hypokyphosis ( brace worsens this)
- Technique
- 23/ 24 hrs until skeletal maturity
good fit of brace essential - monitor
monitor with serial XR eack 4-6/12
can use Boston brace for curve with apex T8 or lower
treat until the end of growth ie Risser 4 or full vertical ht
curve maintained less than 35 deg with brace - no need for surgery
- Weaning from brace
- when vertical growth has ceased
wean 1 hr/ day /mth - thus takes 1 yr to wean to night bracing only- the pt should wear the brace at night only for the next year
- Results
- 10-15% of curves less than 40 deg at onset of bracing go on to fusion
more than 30 % of curves more than 40 deg at onset of bracing go on to fusion
Surgery for idiopathic scoliosis
consider pt factors and XR measurement
- indications
- -curve progressing more than 45 deg should have surgery
- curves with thoracic lordosis have poorer resp function and should be corrected earlier
- cosmesis
When 12 girls , 14 boys with fusion
If operate earlier aim to instrument but not fuse
Should fuse the major (structural) curves and ignore the compensatory (secondary) curves
Include in the fusion area all vertebrae rotated in the same direction as the apical vertebra- ie extend to the first neutral vertebra
Stable zone of Harrington- the lower level of fusion should fall within the zone defined by 2 vertical lines drawn up from the lumbosacral facets
King etal - the stable vertebra is that vertebra most closely bisected by a line drawn up from the centre of S1 with the pelvis levelled- fuse to this vertebra
- Type 1
- fuse both curves to the lower vertebra but no lower than L4
- Type 2
- fuse thoracic curve selectively to the stable vertebra
- Type 3,4
- fuse to include the measured thoracic curve with the lower end of fusion the stable vertebra
- Type 5
- fuse both thoracic curves to the stable vertebra
Flattening of the lumbar spine should be avoided at all costs
Generally assess the mobility of the curve with side bending films before and generally avoid long lumbar fusion if possible
Thoracoplasty (excision of 5 or 6 ribs) in patients with a curve of 90o or more resulted in neither an increase morbidity or decrease pulmonary function
Osteopathic or congenital
75% of curves will progress , ~ 50% will require treatment
Bracing helpful esp in cases where curve is flexible
main indication is to delay surgery as long as possible
If curve progresses despite orthosis surgery indicated
Surgery
Congenital curves usually require orthotic treatment until sufficient growth has occurred however if despite bracing the curve progresses fusion should be performed regardless of age.
Anterior and posterior fusion is required to prevent non uniform growth (crank-shaft phenomenon)
Never wait until the end of growth to treat operatively, if young can instrument without fusion, lengthen during growth (what they lose in growth they make up for in lengthening the spine)
Neuropathic and Myopathic
Hold position until old enough to fuse (after 10 years preferably) as progression is usually continuous and rapid with growth
Molded body jackets used as better tolerated and better pt function than Milwaukee
surgery if curve over 50 deg
Aim to get occiput over S1 and the pelvis level
Luque- often have to fuse from T1-2 to the sacrum
Spinal cord monitoring
ref: Forbes etal Spinal cord monitoring in Scoliosis surgery JBJS 73B: 487-491, 1991
SEP magnitude decreases more than 50% signif chance (38%) of neurological damage
no false negatives ie normal SEP trace= normal neurology
conclude that epidural SEP monitoring is more sensitive than the wake up test
Complications
Brace:
Superior mesenteric artery occlusion of the third part of the duodenum
Pressure sores
Surgery:
Pseudarthrosis now ~ 2% (lumbar more than thoracic and paralytic more than idiopathic)
Neurological complications ~ 3% with CD increasing up to 17% with some techniques without spinal cord monitoring
Crankshaft phenomenon (anterior growth in the presence of solid posterior tether)
Anterior surgery may result in loss of lumbar lordosis and increased chance of back pain
DVT, PE, infection (1.5%) etc
Wake up test:
Accidental extubation
Air embolus
Violent movement 'popped rod'
Prognosis
Probability of a curve progressing is related to the pattern of the curve, the magnitude of the curve, Risser sign, the age at presentation and the menarchal status
Once established the curve is likely to increase during the growing period
Further deterioration in the curve after reaching Risser 4 is slight but curves more than 50o may increase at a rate of 1o per year regardless of maturity
Significant curves in a younger child and higher curves have worse prognosis
Less than 30o most curves are benign and greater than 60o most progress but at variable rates depending on the degree of rotation and location of the curve
Increased vertebral rotation even with low angle scoliosis has increased chance of progression
In adolescence with idiopathic scoliosis whose curves measure less than 30o at skeletal maturity tend not to progress regardless of curve pattern
Progression of curves that are greater than 30o appears to be related to the amount of vertebral rotation with thoracic curves between 50o and 75o progressing most rapidly at about 1o per year
Combined curves tend to balance with age and do not tend to progress unless greater than 60o at cessation of growth
Pain develops in approximately 80% of patients who had an arthrodesis to the fifth lumbar vertebrae in adolescence, 60% of those fused to the fourth, 40% of those to the third and 30% of those to the second lumbar vertebrae.