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Updated: Apr 24 2023

Scheuermann's Kyphosis


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Images scheuermann.jpg[1]_moved.jpg[1]_moved.jpg
  • summary
    • Scheuermann's Kyphosis is a rigid form of spinal kyphosis caused by anterior wedging of >5 degrees across three consecutive vertebrae, most commonly in the thoracic spine.
    • Diagnosis is made with standard and hyperextension lateral radiographs of the thoracic spine.
    • Treatment can be observation or surgical management depending on the severity of kyphosis, presence of neurological deficits, and/or persistent and progressive pain. 
  • Epidemiology
    • Incidence
      • 0.4% to 8.3%
      • most common type of structural kyphosis in adolescents
      • typical age of onset is from 10-12 years age with small subset adult onset
    • Demographics
      • M:F ratio between 2:1 and 7:1
    • Anatomic location
      • usually in thoracic spine
      • less common form occurs in thoracolumbar/lumbar region (see below)
  • Etiology
    • Pathoanatomy
      • exact pathophysiology is unknown but several theories
        • 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
      • most widely accepted theory suggests that the kyphosis and vertebral wedging are caused by a developmental error in collagen aggregation which results in an abnormal end plate
    • Genetics
      • autosomal dominant inheritance pattern now accepted
    • Associated conditions
      • 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
  • Classification
    • Thoracic Scheuermann's Kyphosis
      • most common form
      • curve from T1/2 to T12/L1 with apex between T6-T8
      • better prognosis
    • Thoracolumbar/lumbar Scheuermann's Kyphosis
      • far less common form
      • curve from T4/5 to L2/3 with apex near the thoracolumbar junction
      • associated with increased back pain
      • more likely to be progressive and symptomatic
      • more irregular end-plates noted on radiographs, less vertebral body wedging
  • Presentation
    • Symptoms
      • may complain of thoracic or lumbar pain
      • cosmetic concerns
    • Physical exam
      • increased kyphosis which has a sharper angulation when bending forwards
        • 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
  • Imaging
    • Radiographs
      • recommended
        • AP and lateral spine
      • findings
        • 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
      • controversial as to whether it is indicated prior to surgery to look for associated disc herniation, epidural cyst, spinal cord abnormalities, and spinal stenosis
      • will show vertebral wedging, dehydrated discs, and Schmorl's nodes (herniation of disc into vertebral endplate)
      • any neurological symptom or deficit warrants evaluation with MRI
  • Treatment
    • Nonoperative
      • stretching, observation, physical therapy
        • indications
          • kyphosis < 60° and asymptomatic (mild symptoms)
            • most patients fall in this group and can be treated with observation alone
        • modalities
          • physical therapy
            • postural improvement exercises and back extensor strengthening
            • core muscle strengthening for patients with spondylolysis
            • limited effectiveness
      • bracing with an extension-type orthosis (Jewitt type - with high chest pad)
        • indications
          • kyphosis 60°-80° most effective in those with growth remaining
        • 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
    • Operative
      • posterior spinal fusion ± osteotomy ± anterior release
        • indications
          • kyphosis > 75 degrees
          • neurologic deficit
          • spinal cord compression
          • severe pain in adults
        • techniques
          • Smith-Petersen osteotomy
            • best for long sweeping, global kyphosis
            • less than the typical 10° sagittal plane correction per level given ridigity
          • anterior release
            • technique of the past, rarely done now due to pedicle screw constructs
          • fusion
            • dual rod instrumentation usually performed
        • 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
  • Techniques
    • PSF with dual rod instrumentation +/- anterior release and interbody fusion
      • approach
        • posterior midline to thoracic spine
      • arthrodesis
        • current recommendation is to include entire kyphotic Cobb angle and stop distally to include the first stable sagittal vertebra (first vertebra bisected by the posterior sacral vertical line)
          • previously stopped distally at first lordotic disc but had high incidence of distal junctional kyphosis
      • fixation technique
        • usually a combination of pedicle screws and hooks
          • intra canal hooks may be dangerous at apex of curve as they can potentially compress spinal cord
        • do not always have to instrument at apex
      • correction technique
        • Cantelever - usally two rods placed in top anchors then brought down to bottom pedicle screws
        • Compression across posterior anchors
        • posterior spine shortening technique of Ponte
          • indicated in stiff curves where correction is needed
          • done by removing spinous processes at apex, ligamentum flavum, and performing facet joint resection
        • goal is to obtain correction to final kyphosis of 40-50°
        • in situ bending usually difficult to do and not helpful
      • anterior release and fusion
        • thorascopic anterior discectomy may help avoid morbidity of thoracotomy, but usually not needed
      • neuromonitoring
        • motor and sensory evoked potentials must be monitored intraoperative
  • Complications
    • Neurologic complications
      • reported rate of 0.6-0.8%
        • higher than idiopathic scoliosis corrective surgeries
        • typically due to spinal cord stretching/lengthening (need to ensure there is enough posterior column shortening)
        • neuromonitoring changes warrant reversal of correction
        • overall incidence of complications does not differ between anterior/posterior versus posterior alone procedure
    • Distal junctional kyphosis
      • occurs in 20-30% of patient
      • avoid by
        • making proper selection of fusion levels (use the first stable sagittal vertebra)
        • avoid overcorrection (correction should not exceed 50% of original curve)
    • Proximal junctional kyphosis
      • typically secondary to overcorrection and negative sagittal balance
      • less common that distal junctional kyphosis
    • Pseudarthrosis
    • Hardware failure
    • Loss of correction
    • Superior mesenteric artery syndrome
      • rare
  • Prognosis
    • Back pain in adults that very rarely limits daily activities (mild curves with a mean of 71 degrees)
    • Curves >75 degrees are likely to cause severe thoracic pain
    • Studies suggest at least some progression in 80% of patients but not often to severe deformity
    • Long-standing compensatory lumbar hyperlordosis may lead to lumbar spondylolysis
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