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Abstract
Objective
To evaluate the usefulness of MRI grading of disc degeneration in determining whether L5- S1fusion 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 A P, lateral and flexionextension 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 correlation was found between disc degeneration and instability (P=0.083, P=1.000).
REFERENCES
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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
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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