Updated: 1/20/2019

Scheuermann's Kyphosis

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Introduction
  • A rigid thoracic hyperkyphosis defined by > 45 degrees
  • 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
    • location
      • usually in thoracic spine
      • less common form occurs in thoracolumbar/lumbar region (see below)
  • 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
  • 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
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
Surgical 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 
 

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(SAE07PE.90) Examination of a 13-year-old boy with asymptomatic poor posture reveals increased thoracic kyphosis that is fairly rigid and accentuates during forward bending. The neurologic examination is normal. Spinal radiographs show 10 degrees of scoliosis at Risser stage 2, and there is no evidence of spondylolisthesis. A standing lateral view of the thoracic spine is shown in Figure 41. The kyphosis corrects to 50 degrees. Management should consist of Review Topic

QID: 6150
FIGURES:
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1

electrical stimulation.

2%

(11/659)

2

a Charleston bending brace at night.

3%

(22/659)

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an extension-type spinal orthosis.

62%

(410/659)

4

posterior spinal fusion with instrumentation.

18%

(118/659)

5

anterior spinal release and posterior spinal instrumentation.

14%

(94/659)

L 3

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(OBQ07.149) A 13 year-old boy is brought to your office because his mother is concerned about his poor posture. A lateral radiograph shows thoracic kyphosis of 38 degrees. This likely represents: Review Topic

QID: 810
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1

Normal range of thoracic kyphosis

79%

(3191/4048)

2

Adolescent idiopathic scoliosis

5%

(213/4048)

3

Scheuerman's kyphosis

15%

(588/4048)

4

Pathologic scoliosis

0%

(14/4048)

5

Congenital scoliosis

1%

(22/4048)

L 2

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