Spondylolysis & Spondylolisthesis

Spondylolysis

• Traumatic Pars defect - unilateral
• Common cause of pain in children & adolescents
• Fatigue fracture from repeated hyperextension

Associated with

• Ballet dancers
• Tight hamstrings
• Boys

Diagnosis

• Lateral XR picks up 85%
• Oblique picks up 10% more
• 5% require CT, bone scan, or SPECT (best)

Management

• Symptomatic relief & activity modification
• Bracing
• Non-union common but asymptomatic
• Surgery rarely indicated

Spondylolisthesis

Classification

Type (Wiltse) – Dad Is Down The Pub & Iatrogenic

• Type 1: Dysplastic
• Type 2: Isthmic
  • 2a: Pars stress fracture
  • 2b: Elongated pars
  • 2c: Acute pars fracture
• Type 3: Degenerative
• Type 4: Traumatic
• Type 5: Pathologic
• Type 6: Iatrogenic

Grade (Myerding)

• Grade 1: 0-25% slip
• Grade 2: 25-50% slip
• Grade 3: 50-75% slip
• Grade 4: 75-100% slip
• Grade 5: >100% slip (spondyloptosis)

Radiographic Assessment of SL

• Slip angle – normal = <0
• Sacral inclination – normal = >30°
  • Alteration in both indicates kyphosis – poor prognostic factor
• Pelvic incidence – increase is related to increased progression

General Presenting Features

• Pelvic waddle
• Heart-shaped bottom
• Palpable step
• Mechanical pain
• Neurologic symptoms

Dysplastic Spondylolisthesis

• Not strictly congenital – develops by age 5
• Girls > Boys
• Eskimos

Radiographic Features

• L5/S1 level
• No pars defect – intact neural arch
• Dome-shaped S1
• Incompetent facet joint
  • L5 inferior facet poorly formed, S1 superior facet absent
• Trapezoidal L5
• >30% slip is uncommon

Clinical Features

• Patient presents during growth spurt most commonly
• Slip usually <30%
• High rate of neurologic compromise (cauda equina) with >30% slip
  • Intact neural arch

Isthmic Spondylolisthesis

• Most common type (type 2a is most common, then 2b, then 2c)

Pathology

• Pars interarticularis stress fracture – repeated hyperextension
• Boys > Girls
• Eskimos
• Hyperextension sports

Associations

• Spina bifida
• Scheuermann’s

Radiographic Presentation

• L5/S1
• Sagittally orientated facets but not dysplastic
• Pars defect
• Usually <25% slip

Clinical Features

• Uncommon for slip to progress especially after skeletal maturity
• Mechanical back pain
• Tight hamstrings
• Rare to get neurologic deficit
  • High-grade slips
• L5 exiting root rather than traversing S1 is affected

Risk Factors for Progression

• Girls
• Younger age at presentation
• High-grade slip
• L4/5 or L3/4 slip
  • Iliolumbar ligament stabilises L5/S1

Adult Isthmic Spondylolisthesis

• Present in 30’s usually
• When an adolescent isthmic SL becomes symptomatic
• Due to degenerative process beginning with ageing
• Mechanical pain usually
• Sometimes radicular or stenotic pain
• Pars defect apparent on imaging

Degenerative Spondylolisthesis

• Older adults
• L4/5 most common level

Risk Factors

• Diabetes
• Blacks
• Women > Men
• Sacralised (transitional) L5

Pathology

• DDD with segmental instability
• Facet arthrosis
• Abnormal loading and mechanics

Management of Spondylolisthesis

Low Grade (<50%)

• Try non-operative treatment whatever the case
  • Activity modification
  • Analgesia
  • Flexion exercises
  • Bracing in adolescents/children
• Indication for surgery:
  • Intractable pain
  • Neurologic deficit
  • Progression of slip

High Grade (>50%)

• In adolescents/children:
  • Prophylactic surgery in children – high risk of progression
  • High risk of neurologic compromise, especially dysplastic
• Adults with high-grade slips tend to be symptomatic
  • Surgery is warranted as chance of progression higher
  • Results of surgery better than non-operative for high grade

Surgical Treatment

• Gold standard in all groups:
  • In situ posterolateral instrumented fusion
    • Through a midline approach or Wiltse para-transverse approach
    • Favoured – less disruption to posterior structures
    • Low risk of neurologic compromise
    • Instrumentation increases fusion rate
      • Solid fusion associated with better outcome

Controversies

Slip Reduction

• Not for low-grade slips – risk outweighs benefit
• Indications:
  • Significant L5/S1 kyphosis with hyperlordosis above
  • High slip angle (>45°)
  • Badly altered sagittal balance
• Increases chance of neurologic injury – 10% (most transient)
• May decrease long-term chance of stenosis
• Reduction opens up and re-orientates foramina

Anterior Supplementation

• Should be considered for high-grade slips
• Less stress on posterior instrumentation
• Higher chance of fusion
• Anterior fusion alone does not work as well

ORIF of Pars Defect

• Tension band wiring or compression screw
• 90% rate of union and good outcome
• Best results in:
  • No DDD
  • Single-level slip
  • Low-grade slip
  • No neurologic deficit

Management of Spondyloptosis

• Extremely challenging surgery
• Usually done in a 2-stage procedure:
  • 1st stage: Removes L5
  • 2nd stage: Fuses L4 to sacrum circumferentially