Cervical adjacent segment degenerative disease ; Is it a natural history or fusion disease? -comparison between adjacent level of fusion and non-fusion segment-

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Cervical adjacent segment degenerative disease
Is it a natural history or fusion disease?
-comparison between adjacent level of fusion
and non-fusion segment-         

• Byung-Wan Choi, M.D., Byung-Ryeul Choi M.D.,
• Kyung-Jin Song, M.D. and  Kwang-Bok Lee, M.D.
  
• Departments of Orthopedic Surgery
• Gwangju Veterans Hospital,
• Chonbuk National University Hospital
• -We have no financial relationships to disclose-

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PURPOSE

• The purpose of this study was to evaluate the
  fusion itself can affect the adjacent segment
  degeneration or disease formation by comparing
  the radiological and clinical findings between
  adjacent to fusion segment and non-fusion segment
  in single level anterior fusion cases.

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Demographic Data
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Adjacent to fusion level (Group A)
Adjacent above level
Fusion level
Adjacent below level
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Adjacent to non fusion level (Group B)
Natural Segment
Fusion level
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Radiological criteria of degeneration
(Criteria I)

• 1. Modified Hilibrands adjacent segmental disc
  degeneration.
• 
  
  -JBJS 1999-
• Grade Disease
  Plain Radiography
• ---------------------------------------
  --------------------------------
• I None
  Normal
• II Mild
  Narrowing of disc space (lt50),
  
• 
  no posterior osteophytes
• III Moderate
  50lt Xlt75 of normal disc height,
• 
  posterior osteophyte
• IV Severe
  gt 75 of disc height
• 
  posterior osteophyte
•   ---------------------------------------

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Radiological criteria of degeneration
(Criteria II)

• 2. Development of adjacent-level ossification
• 
  - Park
  et al, JBJS 2005-

Grade II extended across lt 50 of the disc
space
Grade I none
Grade IV complete bridging
Grade III across gt 50 of
the disc space
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Radiological criteria of degeneration
(Criteria III)

• 3. Segmental instability
• - More than 3mm displacement in
  flexion/extension
• - Abnormal motion -Dvorak et
  al, 1988 Spine-

Flex
Flex
Ext
Ext
62 Ms
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Adjacent segment disease

• - interbody fusion may lead to increases in
  mechanical stress at adjacent disc levels,
  thereby accelerating degenerative changes and
  producing clinical symptoms with time the
  so-called adjacent segment disease.
• - Clinical evaluation of new radicular or
  myelopathic symptom occurrence for evaluation of
  adjacent segment disease.
• ? Follow up MRI was performed.

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RESULTS
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Incidence of radiological degenerative change

• 1. The percentage of the cases showed
  degenerative change
• 
  (according to fusion or not)

Group A
Group B
38/457(8)
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Incidence of radiological degenerative change

• 2. The number of the cases showed degenerative
  change
• 
  (in the cases of adjacent to fusion)

Group A
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Analysis according to radiographic criteria
(Criteria I)
(Criteria II)
(Criteria III)
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Incidence of degenerative disease

• Total 4 cases/ 87 patient (4)
• In group A 2/174 segment(1) ? 1
  re-operation (58ms)

58 Ms
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Incidence of degenerative disease

• Total 4 cases/ 87 patient (4)
• In group B 2/283 segment(0.7) ? 1
  re-operation(64ms) p0.59

64 Ms
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CONCLUSION

• Fusion itself can accelerate the severity of
  adjacent level degeneration as compared with
  non-fusion.
• But there was no correlation in the
  incidence of symptomatic adjacent segment
  diseases according to the fusion in single level
  anterior cervical arthrodesis for the
  degenerative cervical diseases.
• Adjacent segment disease is more a result of
  the natural history.