J Korean Soc Spine Surg.  2002 Dec;9(4):305-312. 10.4184/jkss.2002.9.4.305.

The Changes of Adjacent Segments after Fusions (above 3-levels to L5) in Degenerative Lumbar Spinal Disorders

• Kim WJ
• Yeom JS
• Kang JW
• Kim KH
• Oh JU
• Choy WS

• KMID: 2209712
• DOI: http://doi.org/10.4184/jkss.2002.9.4.305

Abstract

STUDY DESIGN: A retrospective study.
OBJECTIVE
To evaluate the usefulness of MRI grading of disc degeneration in determining whether L5-S1 fusion is necessary in degenerative lumbar spinal disorders. SUMMARY OF LITERATURE REVIEW: Changes in adjacent segments are not well understood, after floating fusion has been performed.
MATERIALS AND METHODS
We reviewed 16 surgical cases of degenerative lumbar spinal disorders from July 1996 to February 2000 with an average follow-up of 41 months. Fusion was done in patients without instability, pathology and narrowing of L5-S1. We measured the disc degeneration of adjacent segments in preoperative MRIs using the Modified Pearce classification. In spine AP, lateral and flexion-extension radiographs, we measured disc height, angular motion and instability changes and correlated these with disc degeneration.
RESULTS
Disc height changes decreased in the upper and lower adjacent segments and preoperative disc degeneration above grade IV, decreased more in lower adjacent segment. A statistical correlation was found between disc degeneration and disc height changes in the lower segment (P=0.046), but not in the upper segment (P=0.649). The angular-motion was unchanged in the upper and lower adjacent segments, and no statistical correlation was found between disc degeneration and angular-motion changes (P=0.819, 0.208). Postoperative instability was found in the upper adjacent segment in 2 patients, but no statistical cor-relation was found between disc degeneration and instability (P=0.083, P=1.000).
CONCLUSION
L5-S1 might be saved when free of pathology, and when disc degeneration is below grade III and balanced sagit-tally. However, further study is needed because of the short-term follow up and low number of cases in this study.

Keyword

Degenerative lumbar spinal disorders; Fusions; Adjacent segments

MeSH Terms

Classification
Follow-Up Studies
Humans
Intervertebral Disc Degeneration
Magnetic Resonance Imaging
Pathology
Retrospective Studies
Spine

Figure

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  Fig. 1. Grading system for the assessment of lumbar disc degeneration.

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  Fig. 2. Disc height measurement Fig. 2. • Frymoyer method Fig. 2. A/B× 100(%)

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  Fig. 3. Angular motion measurement Fig. 2. • Dupuis method Fig. 2. θ E~θ F

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  Fig. 4. Aota’s criteria of instability Fig. 4. > 15°rotatory hypermobility Fig. 4. > 3 mm anterior translation Fig. 4. > 3 mm posterior translation Fig. 4. > 3 mm lateral translation Fig. 4. > 5°disc wedging

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  Fig. 5. Disc height change according to disc degeneration (MRI grade)

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  Fig. 6. Angular motion change according to disc degeneration (MRI grade)

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  Fig. 7. 65-year-old woman with degenerative lumbar scoliosis shows less changes of the disc space ratio and the angular motion in the upper & lower adjacent segments after follow-up 5 years 2 months (MRI grade- upper: IV, lower: III).

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  Fig. 8. 64-year-old woman with degenerative lumbar scoliosis shows decreased changes of the disc space ratio in the upper & lower adjacent segments and less chnages of the angular motion in the upper & lower adjacent segments after follow-up 4 years 4 months (MRI grade- upper: IV, lower: IV).

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