J Korean Soc Spine Surg.  2004 Dec;11(4):231-237.

Altered Sagittal Rotation After Segmental Fusion in Degenerative Lumbar Disease: Comparative study by level, length of fused segments

• Lee S
• Ahn DK
• Jeong KW
• Kim HS
• Seo YH
• Park HS

Abstract

STUDY DESIGN: A stratified sampling and retrospective study.
OBJECTIVES
To investigate the quantitative change in the sagittal rotation of the whole lumbar spine and adjacent segments after a lower lumbar segmental fusion in humans, according to the site, length, lordosis, age and gender. LITERATURE REVIEW SUMMARY: There have been many reports on experimental animal and human cadaveric studies. However, comparative studies on real patients are very rare.
MATERIALS AND METHODS
One hundred cases of lumbar segmental fusion were selected by stratified sampling. These were divided into 5 groups: L34, L45, L5S1, L345 and L45S1, with each group containing 20 cases. Maximum flexion and extension decubitus films were checked preoperatively and 1 year postoperatively. The sagittal rotation of the whole lumbar spine and adjacent segments were compared. Statistical analyses were carried out with paired t, chi square test and ANOVA, according to the characteristics of variance.
RESULTS
The sagittal rotation of the whole lumbar spine was reduced significantly, from 32.9+/-10.6 degrees to 24.6+/-10.7 degrees, postoperatively (p=0.000). The reduction in 2 segment fusion (10.1+/-11.3 degrees) was greater than for 1 segment fusion (8.4+/-11.6 degrees), but this was not statistically significant (p=0.462), there were no differences between the group (p=0.560). Sagittal rotation of the proximal adjacent segment was increased significantly, from 5.6+/-3.2 degree to 7.7+/-4.1 degrees, postoperatively (p=0.000). The increment for a 2 segment fusion (2.8+/-4.4 degrees) was greater than for a 1 segment fusion (1.7+/-4.2 degrees), but this was not significant (p=0.204), and there were no differences between the groups (p=0.350). The sagittal rotation of the distal adjacent segment showed only a trivial change from, 7.7+/-4.7 degrees to 7.0+/-5.2 degrees(p=0.314).
CONCLUSIONS
After the fusion of one or two segments of the lumbar spine, the sagittal rotation of the whole lumbar spine decreased by about 25%, i.e. patients were considered to conform to a reduced number of motion segments, but the rotation of proximal adjacent segments increased by about 37%. However, the distal adjacent segment showed no changes, i.e. adjacent segment degeneration can develop at the proximal site more frequently. Differences according to the level, age, gender and lordotic angle were not significant.

Keyword

Segmental fusion; Sagittal rotation; Adjacent segment

MeSH Terms

Animals
Cadaver
Humans
Lordosis
Retrospective Studies
Spine

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