Spinal Deformity Pathologiesand Treatments

Spinal Deformity• Scoliosis

– 3-dimensional deformity affecting all 3 planes

– Can be difficult to visualize with 2-dimensional radiographs

• Kyphosis– Deformity affecting the sagittal plane

• Neuromuscular– Results from neurologic or muscular

diseases, such as cerebral palsy, muscular dystrophy, or polio

Types of Scoliosis• Adult• Congenital

– Abnormal development of the spine resulting in:

• A missing portion• Partial formation• Lack of separation of the vertebrae

• Idiopathic– Infantile– Juvenile– Adolescent

• Neuromuscular– Results from neurologic or muscular

diseases, such as cerebral palsy, muscular dystrophy, or polio

Scoliosis“Normal” alignment• Spinous processes all line

up in a straight line over the sacrum

Normal sagittal alignment• Visibly balanced; a vertical line from

the midpoint of the C7 body to the posterior superior corner of the sacrum

• Coronal plane deformity almost always correlates with sagittal plane deformity, specifically hypokyphosisand hypolordosis

ScoliosisC7

Lateral displacement

Scoliosis

Angular displacement

Scoliosis

Structural curves (curve stiffness)• Some curves are structural

curves, while others are nonstructural (often the minor curves)

• Determined with bending films (x-rays taken while the patient is bending to each side)

• Stiffness of a curve will influence surgical strategy

Scoliosis

ScoliosisThink in 3 dimensions• Rotational

displacement• Lateral displacement• Sagittal displacement

• Rib hump• Rib cage volume

ScoliosisThink in 3 dimensions• Rotational

displacement• Lateral displacement• Sagittal displacement

• Rib hump• Rib cage volume

Scoliosis• Pediatric

– Congenital• Malformation of spinal segments

– Idiopathic• Infantile (<3 years of age)• Juvenile (3-10 years)• Adolescent (>10 years)

• Adult– Idiopathic; former adolescent,

now skeletally mature – Degenerative; usually >age 40

• Abnormal development of the spine resulting in:– A missing portion– Partial formation– Lack of separation of

the vertebrae

Congenital Scoliosis

Failure of Formation Failure of Segmentation

Congenital Scoliosis

Risk of progression• >30° = 50% • 5-30° = 25% • 25% are nonprogressive

Congenital Scoliosis

Pediatric Idiopathic Scoliosis• Idiopathic

– Infantile/congenital (<3 years of age)• More boys than girls• 80% resolve without

treatment– Juvenile (3-10 years)

• Equally affects boys and girls

– Adolescent (>10 years)• 80% of patients are girls

• Frequency and prognosis (within the general population)– ≤ 10º occurs in 5.0% – ≤ 20º occurs in 0.5%– ≤ 30º occurs in 0.2% – ≥ 40º occurs in 0.1%

• Most patients with scoliosis have small curves• The greater the degree of curve, the more likely

the progression• The greater the amount of growth after the

onset of the curve, the more likely the progression

Adolescent Idiopathic Scoliosis

Adolescent Idiopathic Scoliosis• Treatment options

– Observation • Curves <25° with follow-up radiographs at regular intervals

– Bracing • Curves that range from 25°-40° with flexibility• Curves from 40°-50°• Smaller curves 20°-25° that demonstrate rapid progression

– HIGH NONCOMPLIANCE RATE

– Surgical intervention • Inflexible curves that exceed 40°• Virtually any curve that exceeds 50°

Adult Scoliosis• Idiopathic

– Once an adolescent becomes skeletally mature, change diagnosis to adult idiopathic

• Degenerative– Occurs over a long period time– Usually concomitant with other conditions

• Failed conservative treatment (bracing) will lead to surgical treatment– Decompression with fusion

Adult Scoliosis

Kyphosis• A spine affected by kyphosis shows

evidence of a forward curvature of the vertebrae in the upper back area, giving a "humpback" appearance

• Causes– Metabolic problems– Neuromuscular conditions– Osteogenesis imperfecta, also called

“brittle bone disease”; a condition that causes bones to fracture with minimal force

– Spina bifida– Scheuermann's disease, a condition that

causes the vertebrae to curve forward in the upper back area; the cause of Scheuermann's disease is unknown and commonly seen in males

Principles of Deformity Correction• There are a number of strategies that can

be used to correct spinal deformity• Each of the strategies has its own

pros and cons

• Some strategies use only 1 or 2 principles, and some strategies will use a combination of principles

PRO

CON

Surgical Correction of ScoliosisCurve stiffness• “Stiff” (usually the major

curve); some are “flexible”(often the minor curves)

• Determined with bending films (x-rays taken while the patient is bending to each side)

• Stiffness of a curve will influence surgical strategy

Surgical Correction of ScoliosisCurve stiffness • The stiffness of a curve

will influence surgical strategy because a stiff curve resists correction– Posterior articular

facetecomy– Anterior release– Costal facet releases– Rib osteotomy

Principles of correction• Pioneered by Harrington

– Distract concave side– Compress convex side

• Can correct lateral and angular displacement

• High stress on bones and hardware

• Straight rod = straight spine = “flat back”

• Does not correct rotational deformity

Surgical Correction of Scoliosis

PRO

CON

CON

CON

Surgical Correction of ScoliosisPrinciples of correction• Pioneered by Luque• Translation: bring

the spine to the rod• Can correct lateral and

rotational deformity• High stress on bones

and hardware• Long-term maintenance

of correction is difficult

PRO

CON

CON

Surgical Correction of ScoliosisPosterior approach• Translation (wires/cables)• Pioneered by Luque

– Translation with wires at every level

• Low profile• Inexpensive• Long-term fixation can be

difficult to maintain

PRO

CON

PRO

Surgical Correction of ScoliosisPosterior approach• Translation (wires/cables)• Pioneered by Luque

– Segmental translation with wires at every level

• Low profile• Inexpensive• Long-term fixation can be

difficult to maintain

PRO

CON

PRO

Surgical Correction of ScoliosisPosterior approach• Translation (wires/cables)• Pioneered by Luque

– Segmental translation with wires at every level

• Low profile• Inexpensive• Long-term fixation can be

difficult to maintain

PRO

CON

PRO

Surgical Correction of ScoliosisPosterior approach• Spinal-sacro-pelvic fixation• Also known as Luque-

Galveston• Rods (or bolts) extend into

the iliac crest (between the cortical walls), connect to sacrum, then extend up along the spine; this is state-of-the-art for neuromuscular patients

Principles of correction• Pioneered by Cotrel

and Dubousset– Derotation; proper sagittal

contour (kyphosis and lordosis) approximates spinal deformity when rotated 90º; translate spine to rod, then rotate rod in axial plane

• Simple and quick• High stress to bones and

hardware

Surgical Correction of Scoliosis

CON

PRO

Surgical Correction of ScoliosisPrinciples of correction• Pioneered by Cotrel

and Dubousset– In situ bending; spine is

fixed to rod, then rod is bent to the desired shape

• Will correct lateral deformity• High stress on bones

and hardware• Difficult over long curves• Difficult with titanium rods

CON

PRO

CON

CON

Surgical Correction of ScoliosisPrinciples of correction• Pioneered by Shufflebarger

– Segmental; distraction, compression, and translation applied to each level; segment by segment

• Comprehensive• Lower stress on bones and

hardware means that smaller rods and lower profile connectors can be used

• Complex

PRO

CON

PRO

Surgical Correction of ScoliosisPosterior approach• Translation (Cantilever)• Dr Asher• Concave side first

– T3 down-going lamina hook

– T4 up-going lamina hook

– Wires or cables at curve’s apex

– L1 and L2 pedicle screws and slotted connectors

PRO

PRO

PRO

PRO

Surgical Correction of ScoliosisPosterior approach• Translation (Cantilever)• Dr Asher• Convex side next

– T3 down-going lamina hook• Compress toward T9

– T9 up-going lamina or pedicle hook (at the convex apex)

• Compress toward T3– L1 and L2 pedicle screws

with slotted connectors

PRO

PRO

PRO

PRO

Surgical Correction of ScoliosisPosterior approach• Translation (Cantilever)• Dr Asher• Convex side next

– T3 to T9 compression pulls lateral displacement into alignment, and brings distal rod end toward center line

PRO

PRO

Surgical Correction of ScoliosisPosterior approach• Segmental• Dr Shufflebarger

“Open the closed spaces, and close the opened spaces [segment by segment]”

Surgical Correction of ScoliosisPosterior approach• Segmental• Dr Shufflebarger

“Open the closed spaces, and close the opened spaces [segment by segment]”

Surgical Correction of ScoliosisPosterior approach• Segmental• Dr Shufflebarger

“Open the closed spaces, and close the opened spaces [segment by segment]”

Surgical Correction of ScoliosisPosterior approach• Segmental• Dr Shufflebarger

“Open the closed spaces, and close the opened spaces [segment by segment]”

Surgical Correction of ScoliosisPosterior approach• Segmental• Dr Shufflebarger

“Open the closed spaces, and close the opened spaces [segment by segment]”

Surgical Correction of ScoliosisPosterior approach• Segmental• Dr Shufflebarger

“Open the closed spaces, and close the opened spaces [segment by segment]”

Surgical Correction of ScoliosisAnterior correction• Mechanics limited to

– Segmental distraction and compression for correction of lateral displacement

– Derotate for correction of saggital displacement

– In situ bending– Effective translation is very

difficultCON