· Gr spondylos (vertebra) and olisthanein (to slip)
· coined in 1854 by Kilian
· forward slip of one vertebral body relative to subjacent one
· Wiltse, Newnham and McNab (1976)
· occurs at L5-S1
· associated with congenital dysplasia of upper sacrum
· hypoplasia of superior articular facets of S1
· due to discontinuity of pars interarticularis
· almost always occurs at L5S1
· three subtypes
1. type A
· lytic type
· results from separation of pars
2. type B
· elongated type
· results from healing of microfractures
3. type C
· acute type
· from trauma
· due to degenerative arthritis of facet joints
· occurs after middle age
· usually occurs at L4-L5
· due to severe trauma with bilateral acute fractures through neural arch outside pars
· attenuation of neural arch or pedicle
· due to various processes that weaken bone
· osteogenesis imperfecta
· osteoporosis
· postsurgical with excessive resection of neural arches / facets
· incidence of spondylolysis is 5%
· incidence of spondylolisthesis is 2.5%
· occurs in children after they are able to walk
· never present at birth
· rare under age 5
· usually appears at age 7 or 8 yrs
· incidence increases until age 20
· more common in boys
· girls have greater degree of slip
· most common at L5-S1 level
· isthmic type
· most common form
· commonest cause of slip in age < 50 yrs
· dysplastic type
· rare
· increased incidence of neurological deficit
· fatigue fracture of pars interarticularis
Theory
· extension of lumbar spine concentrates shear stresses on pars interarticularis
· pars prone to fracture because
· pars thin
· disc less resistant to shear
· can occur at physiological loads during cyclic flexion-extension motion of lumbar spine
· stresses may be further accentuated by lateral flexion with spine extended
Evidence
· not seen in infants
· not seen in non-walkers secondary to neuromuscular disease
· common in female gymnasts
· incidence of 10%
· sometimes seen with initial normal radiographs
· increased incidence with thoracolumbar Sheuermann’s disease
· incidence of 40%
· SD due to excessive and repeat mechanical loading on immature spine
· kyphosis may lead to increased lumbar lordosis
· spondylolisthesis seen in
· soldiers
· weightlifters
· football players in the line
Theory
· inherited condition
Evidence
· increased incidence in families
· 33% of affected relatives with dysplastic type
· 15% of affected relatives with isthmic type
· relatives may have opposite type
· racial differences
· more common in whites
· increased incidence in Eskimos
· associated with increased incidence of
· sacral spina bifida
· dysplasia of superior sacral facets
· posterior defects found in
· 95% of dysplastic type
· 32% of isthmic type
· congenital deficiencies of posterior structures important in dysplastic type
· developmental factors (trauma, posture, repetitive activities) important in pars defect and isthmic type
· L5 nerve root pressure may be caused by
· fibrocartilagenous mass at pars defect
· stretching of root over posterior part of sacrum
· cauda equina pressure may be caused between
· intact neural arch of L5 pulled forward
· posterior body of sacrum
· symptoms uncommon in childhood
· develop in 13% under age 18
· if do develop, occur at adolescent growth spurt
· most common presentation in children is postural deformity or abnormal gait
· most common presentation in adults is pain
Pain
· in low back and posterior buttocks and thighs
· initiated by strenuous activity
· esp. repetitive flexion extension
· eg. rowing, gymnastics, diving, serving in tennis
· relieved by rest
Neurology
· occasionally have radicular pain in legs
· rarely distal to knees
· rarely have objective nerve root compression signs
Gait
· abnormal gait due to tight hamstrings
· tight hamstrings present in 80% of symptomatic patients
· seldom accompanied by neurological signs
· probably due to reactive spasm to pelvic tilt
· cause posterior pelvic tilt and limitation of hip flexion
· result is stiff-legged and short-stride gait with pelvic rotation
· called pelvic waddle
· may walk on toes with knees bent
Appearance
· lumbosacral kyphosis
· compensatory increased lumbar lordosis
· step-off or depression
· flattened heart-shaped buttocks
· vertical sacrum (variable)
· short trunk
· protruberant abdomen
Spine
· tenderness in low back
· restriction of lateral flexion
Scoliosis
· increased incidence in symptomatic spondylolisthesis
· 25-50%
· more common in dysplastic form
· more common in girls
· may be
· sciatic (due to muscle spasm)
· olisthenic (due to rotation at level of slip)
· idiopathic (structural)
· 1st 2 forms settle with resolution of slip
· idiopathic form should be treated as separate entity
Posterior elements
Spondylosis
· radiolucent defect of pars interarticularis
· if large, seen on all radiographs
· if small, need oblique views
· Scotty dog sign of Lachapele
· defect appears as collar
· may be unilateral or bilateral
· if unilateral, may be contralateral sclerosis of pars
· due to compensatory hypertrophy
Isthmic type
· bilateral sponydylosis
· defect may be
· acute wih narrow gap and irregular edges
· elongated with thinning
· chronic with wide gap and smooth sclerotic edges
· L5 posterior elements maintain normal position
· L4 posterior elements displaced forward
Dysplastic type
· inferior facets of L5 sublux ventrally on sacral facets
· pars may become attenuated
· greyhound sign of Hensinger
· pedicles appear elongated
· L5 posterior elements displaced forward
Vertebral bodies
· degree of slip varies with position
· standing vs supine
· flexion vs extension
Tangential slipping
· L5 slides forwards on S1
· classified by Meyering
· according to degree of slip cf. width of S1
1. Grade I
· 0-25%
2. Grade II
· 25-50%
3. Grade III
· 50-75%
4. Grade IV
· 75-100%
5. Grade V
· > 100%
· spondyloptosis
Angular slipping
· L5 tilts forward on sacrum
· referred to as slip angle of Boxall
· quantified by measuring angle between
· line along inferior body of L5
· line at right angles to line along posterior body of S1
· results in relative lumbosacral kyphosis
· adaptive changes may occur
· anterior and posterior parts of sacrum erode
· sacrum becomes domed in middle
· L5 becomes trapezoidal in shape
· posterior height less than anterior height
· measurement of wedging referred to as lumbar index
· progression leads to more vertical orientation of sacrum and pelvis and forward movement of lumbar spine
· called teeter-totter appearance
Progression
· by early adulthood
· L5-S1 disc narrowed
· anterior sacrum develops sclerotic lip
· makes further slip unlikely in adulthood
· can detect lesion early
· useful in acute phase
· can detect osseous activity in lesion
· useful in distinguishing between nonunion and progressive healing
· SPECT usually required to identify lesion
· rarely indicated
· superceded by MRI
· rarely indicated
· consider if
· neurological signs that do not setle with rest
· possibility of coexisting lesion
· bladder dysfunction
· perineal anasthaesia
· uncommonly is cause of back pain in children
· rarely is cause of neurological deficit
· should look for
· vertebral osteomyelitis / discitis
· osteoid osteoma
· spinal cord tumour
· herniated disc
· Scheuermann’s disease
· inflammatory spondylitis
· may occur while growth continues
· never occurs once growth ceases
· number of risk signs identified
Risk of progression
Clinical
· young age (progression during growth spurt)
· female sex
· recurrent back pain
· postural deformity or abnormal gait from tight hamstings
Radiological
· dysplastic slip
· grade III or IV slip
· angle of slip > 10o
· instability with teeter-totter appearance
· increased incidence of L5-S1 disc degeneration
· no significant increase in low back pain
· comparison of fusion vs no fusion (Winter)
· fusion
· 55% excellent
· 35% good
· 10% poor
· no fusion
· 35% excellent
· 55% good
· 10% poor
Nonoperative
Observation
· if symptoms minimal
· until skeletal maturity
Activity modification
· restriction of vigorous activities
· strengthening of back and abdomen
· only while symptomatic
· no evidence that physical activity hastens progression
Brace immobilisation
· may be indicated in
· acute onset of symptoms with definite episode of injury
· failure to respond to activity modification
· in form of anterior opening polypropylene antilordosis brace
Operative
· fusion of pars
· indicated in
· failure to respond to rest or cast
· pain that interferes with desired activities
Nonoperative
Indications
· slip < 25%
· no further growth
Technique
· as above
· observation
· activity modification
· brace immobilisation
Results
· ineffective in 50% of patients
· more effective if few risk features
Operative
Indications
· skeletally immature AND
· slip > 25-50% (Winter 25%, Wiltse 30%, Hensinger 50%) OR
· pain that interferes with desired activities
Technique
· posterolateral fusion
Reduction
· controversial
· combination of
· preoperative traction
· instrumented fusion
· may be indicated because of
· improvement in posture
· improved cosmesis
· increased pain relief
· significant risk of neurological deficit
Technique
· lesion identified and debrided
· iliac crest bone graft harvested and inserted
· pars fixed by
· tension band wire around spinous process and transverse process (Bradford)
· lag screw from inferior facet to superior facet (Buck)
· AO hook-screw device
· 80% good or excellent results
Technique
Posterolateral fusion
· midline or Wiltse approach
· transverse processes and sacral ala decorticated
· iliac crest bone graft harvested and inserted
· fusion length
· L5 to S1 in Grade I and II
· L4 to S1 in Grade III and IV
Laminectomy
· seldom indicated
· indicated if
· neurological signs
· lesion found on MRI
· should combine with fusion
Reduction
· surgical reduction can be performed with posterior instrumentation
· esp. pedicle screws
· may be combined with anterior fusion
· technically difficult
Gill procedure
· isolated removal of loose elements and removal of fibrocartilage at pars defects
· contraindicated in children
· slip may progress
Postoperative
· brace for 3 months
· no vigorous activities for 6 months
Results
· 90% resolution of pain
· 90% solid fusion
· hamstring tightness usually resolves completely
· most resume unrestricted activities
· little cosmetic improvement
Complications
Pseudarthrosis
· decreased with
· lateral technique
· avoidance of decompression
· use of cast
Progression
· in association with apparently solid fusion
· occurs after 25%
· related to
· high angle of slip (> 35%)
· poor lateral fusion
· inadequate immobilisation
Neurological deficit
· with instrumented reduction
· more common in females (M:F = 5:1)
· most common at L4-L5 level
· body weight displaces lumbar vertebrae ventrally
· resisted by facet joints
· sagittal orientation of facet joints obviates restraining effect
· predisposes to
· premature facet degeneration
· spondylolisthesis
· concomitant disc degeneration
· slip usually mild
· average 15%
· maximum 30%
· facet involvement may be asymmetrical
· causes rotatory component
· osteophyte formation at posterior portion of superior articular facet causes compression of lateral recess
· usually leads to compression fo interior roots (L5)
· if severe, can affect superior root (L4)
· low back pain (80%)
· sciatica (50%)
· neurogenic claudication (50%)
· cauda equina (5%)
· normal lumbar forward flexion
· minimal tenderness and spasm
· neurological deficit (50%)
· sensory alteration (30%)
· weakness (20%)
· AP shows
· facet hypertrophy
· osteophyte formation
· lateral shows
· mild forward slip
· disc narrowing
· oblique shows
· intact pars
· facet degeneration
· myelogram shows
· hourglass constriction at level of slip
· blunting of involved root sleeves
· CT shows
· degeneration of facet
· degenerative disc disease
· pseudodisc herniation
· may replace CTM
Indications
· mild symptoms
· short duration
· unfit for surgery
Technique
· activity modification
· analgesics
· brace
· physio
Indications
· failure of nonoperative treatment
Technique
· decompression
· posterolateral fusion
Results
· reduction or elimination of symptoms in 70-80%
Complications
· increasing slip
· if fusion not performed