Neurosurgery notes/Spine/Deformity/Thoracic and lumbar deformity/Kyphosis/Paediatric kyphosis/Scheuermann’s kyphosis

Scheuermann’s kyphosis

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Paediatric kyphosis

General

  • Aka
    • Scheuermann’s disease
  • Sorensen diagnostic criteria
    • Presence of Kyphosis
      • Thoracic spine kyphosis >40° (normal 25-40°) OR
      • Thoracolumbar spine kyphosis >30° (normal ~ 0°)
    • AND
      • At least 3 adjacent vertebrae demonstrating wedging of >5°
    • Other signs include:
      • Vertebral endplate irregularity due to extensive disc invagination
      • Intervertebral disc space narrowing, more pronounced anteriorly
  • Scheuermann kyphosis has two problems
    • Thoracic kyphosis AND
    • Lumbar hyperlordosis

Numbers

  • Incidence between 1% and 6%
  • M:F ratio between 2:1 and 7:1
  • Most common type of structural kyphosis in adolescents
  • Typical age of onset is from 10-12 years age with small subset adult onset
    • 5% of adolescent population
  • 2nd most common cause of back pain in children
    • 1st most common is spondylosis and spondylolisthesis
  • Scoliosis is a feature in 1/3 of cases of Scheuermann’s kyphosis, may be amplified by Adam forward bending test

Classification

  • Type I
    • Thoracic kyphosis
      • Curve from T1/2 to T12/L1
    • Apex at mid thoracic level (T7-9)
    • Has a hereditary component
    • Better prognosis
    • Cervical spine is more lordotic
  • Type II
    • Thoracolumbar kyphosis
      • Curve from T4/5 to L2/3
    • Apex at thoracolumbar region (T11-12)
    • More back pain
    • Affects predominantly athletes and laborers.
    • More likely to be progressive and symptomatic
    • More irregular end-plates noted on radiographs, less vertebral body wedging
notion image

Aetiology

  • Unknown
  • Theory
    • A developmental error in collagen aggregation which results in an abnormal end plate → vertebral wedging → kyphosis
      • most widely accepted theory
    • Osteonecrosis of anterior apophyseal ring
    • Herniation of disc material leading to loss of anterior disc height
    • Relative osteoporosis leading to compression deformity
    • Altered biomechanics leading to anterior wedging and subsequent growth arrest
  • Genetics
    • Autosomal dominant inheritance pattern now accepted

Clinical features

  • Symptoms
    • Pt approaching the end of skeletal growth presents with back deformity and/or pain.
    • Thoracic pain usually centred over apex of the curve
      • Commonest cause of back pain in adolescent
      • Back pain is severe when excessive lordosis is present
    • Absence of radiating pain to the lower limbs
    • Reduced ROM of the lumbar spine Hamstring tightness
    • Restrictive lung disease has been reported in patients with curvature greater than 100 deg
    • Cosmetic concerns
  • Signs
    • Increase in kyphosis (as a sharper angulation) when bending forwards
      • Not corrected by active extension (unlike in postural kyphosis)
    • Normal thoracic kyphosis is between 20 degrees and 45 degrees
    • May have a compensatory hyperlordosis of the cervical and/or lumbar spine
    • Tight hamstrings, iliopsoas, and anterior shoulder
    • Neurological deficits rare but need full examination
  • Can lead to
    • Orthopaedic manifestations
      • Lumbar hyperlordosis
      • Spondylolysis in lumbar region (33%)
      • Scoliosis (33%)
      • Dural cysts
      • Compensatory tightness of anterior shoulder, hamstrings, and iliopsoas muscle
    • Non-orthopaedic manifestations
      • Pulmonary issues in curves exceeding 100 degrees

Radiology

  • Radiographs:
    • Standing lateral spine mainly
      • Anterior wedging across three consecutive vertebrae >5 degree
      • Disc narrowing
      • Endplate irregularities
      • Schmorl's nodes (herniation of disc into vertebral endplate)
      • Scoliosis
      • Compensatory hyperlordosis
      • Spondylolysis on dedicated lumbar films if patient has low back pain
      • Determine sagittal balance by dropping C7 plumb line
    • Hyperextension lateral radiograph
      • Supine lateral radiograph with patient lying in hyperextension over a bolster
      • Can help differentiate from postural kyphosis
      • Scheuermann's kyphosis usually relatively inflexible on bending radiograph
  • CT scan
    • Usually not needed
  • MRI
    • Look for
      • Disc herniation
      • Epidural cyst
      • Spinal cord abnormalities
      • Spinal stenosis
      • Key findings in Scheuermann’s kyphosis
        • Vertebral wedging
        • Dehydrated discs
        • Schmorl's nodes (herniation of disc into vertebral endplate)
    • Any neurological symptom or deficit warrants evaluation with MRI

Management

  • Conservative
    • Aim
      • Correct the abnormal growth direction
      • Enhance local growth
      • Halt kyphosis progression (or gain correction)
    • Principles:
      • By applying forces to unload the anterior portion of the vertebral bodies
    • Options
      • Observation
        • Indicated
          • Kyphosis <50 deg
      • Physiotherapy and extension exercise
      • Extension type bracing
        • Indication
          • curves between 45° and 74° with 2 years of growth remaining and greater than 5° wedging.
        • May help back pain
        • Reasonably successful in preventing progression in skeletally immature patients
        • Curves greater than 70 deg respond less favorably to brace
        • Techniques
          • Milwaukee type brace
              • An apex at T9 or above
               
              notion image
          • A thoracolumbar orthosis (TLSO)
            • Indicated for apex is below T9
        • Braces should be updated every 4-6 months to maximize deformity correction and weaned with skeletal maturity.
    • Outcomes
      • Patient compliance is often an issue
      • Most favorable in curves <65°, correction of >15° in brace
      • Usually does not lead to correction but can stop progression
  • Surgery
    • Indication
      • Skeletally immature adolescent
        • painful kyphosis > 75° with local wedging > 10° not responsive to 6 months of bracing,
      • Skeletally mature patients
        • painful deformity resistant to bracing,
        • curves > 80°
      • Curve progression
      • Unacceptable cosmesis
        • Kyphosis > 75 degrees
      • Neurologic deficit
        • Spinal cord compression
    • Aims
      • Correct the kyphosis to the upper limit of the normal range.
        • Overcorrection may cause adjacent level junctional problems.
        • Correct deformity within normal range taking into account pelvic incidence
      • Alleviate pain
      • Restore global sagittal alignment
      • Prevent curve progression
      • Correct end vertebrae selection to avoid PJK and DJK
    • Decompression
      • A ligamentum flavum excision should be performed at the apex to prevent buckling of the ligament and therefore decrease the risk of neurological deficit.
    • Techniques (osteotomies)
      • Anterior Approach
        • If deformity is very rigid and curve is > 100 degrees esp in adult cases
        • Anterior release
          • Technique of the past, rarely done now due to pedicle screw constructs
      • Posterior Approach
        • Most can be managed in with segmental fixation
        • Posterior osteotomies
          • Grade 1- Smith Petersen osteotomy
            • Best for long sweeping, global kyphosis
            • Less than the typical 10° sagittal plane correction per level given rigidity
          • Grade 2 Ponte osteotomy
            • alone with multi-level Ponte Osteotomies & segmental screw fixation is the treatment of choice
          • 3 column osteotomies (PVCR) may be necessary for very severe and rigid deformities in patients who are not a candidate for anterior surgery due to pulmonary disease
        • Reduction using the cantilever manoeuvre
            • notion image
    • Where to start and where to end fixation
        • Distal
          • The most distal fused vertebrae should be touched by the PSVL (Posterior sacral vertical line) is called the sagittal stable vertebra (SSV)
        • Proximal
          • T2 in most cases
        notion image
    • Outcomes
      • Studies show 60-90% improvement of pain with surgery (no correlation with amount of correction)
      • Studies suggest residual curves >75° lead to worse functional outcomes
      • Complications
        • Kyphosis greater than 100 deg can affect pulmonary function
        • Surgical site infection and neurological complications are more common in SK
        • SK has a higher risk for re-operation than AIS
        • Instrumentation failure (hook or screw pull out) is common post-surgery
        • Development of proximal junctional kyphosis (PJK) after surgery occurs in 1/3 of patients
          • Lumbar lordosis reduction correlates with the amount of thoracic kyphosis correction
          • Significant thoracic kyphosis correction can cause mismatch between PI and lumbar lordosis in type I
          • Correlation between PI-LL < +/-10 deg
          • The chance of developing PJK is much more in type I with larger pre- operative PI values

DDx

Feature
poor posture (postural kyphosis)
Scheuermann’s kyphosis
Curve Rigidity
Less rigid
More rigid
Correct with hyperextension
Yes
No

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