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-

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.

PURPOSE

Demographic Data

Adjacent to fusion level (Group A)

Fusion level

Adjacent above level

Adjacent below level

Adjacent to non fusion level (Group B)

Fusion level

Natural Segment

Radiological criteria of degeneration (Criteria I)

1. Modified Hilibrand`s adjacent segmental disc degeneration. -JBJS 1999- Grade Disease Plain Radiography ----------------------------------------------------------------------- I None Normal II Mild Narrowing of disc space (<50%),

no posterior osteophytes III Moderate 50< X<75% of normal disc height, posterior osteophyte IV Severe > 75% of disc height posterior osteophyte

  ---------------------------------------

Radiological criteria of degeneration (Criteria II)

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

2005-

Grade I : noneGrade II : extended across < 50% of the disc space

Grade III : across > 50 % of the disc space

Grade IV : complete bridging

Radiological criteria of degeneration (Criteria III)

3. Segmental instability

- More than 3mm displacement in flexion/extension

- Abnormal motion -Dvorak et al, 1988 Spine-

62 MsFlex FlexExt Ext

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.

RESULTS

Incidence of radiological degenerative change

1. The percentage of the cases showed degenerative change

(according to fusion or not)

38/457(8%)

Group A Group B

Incidence of radiological degenerative change

2. The number of the cases showed degenerative change

(in the cases of adjacent to fusion)

Group A

Analysis according to radiographic criteria

(Criteria I) (Criteria II) (Criteria III)

Incidence of degenerative disease

Total: 4 cases/ 87 patient (4%)

In group A: 2/174 segment(1%) → 1 re-operation (58ms)

58 Ms

Incidence of degenerative disease

Total: 4 cases/ 87 patient (4%)

In group B: 2/283 segment(0.7%) → 1 re-operation(64ms) p=0.59

64 Ms

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.

CONCLUSION