Table 1.
Baseline characteristics and preexisting degenerative pathologies
| Characteristic | ASD (n = 30) | Non-ASD (n = 31) | p-value |
|---|---|---|---|
| Sex | 0.934 | ||
| Male | 9 (30) | 9 (29) | |
| Female | 21 (70) | 22 (71) | |
| Age (yr) | |||
| Mean± SD | 59.6 ± 8.5 | 63.2 ± 8.1 | 0.091 |
| Range (IQR) | 54.3–66.0 | 55.0–70.0 | |
| BMI | |||
| Mean± SD | 24.0 ± 3.8 | 23.9 ± 2.3 | 0.868 |
| Range (IQR) | 22.6–25.6 | 21.9–25.0 | |
| Follow-up | |||
| Mean± SD | 68.5 ± 11.1 | 71.8 ± 12.0 | 0.264 |
| Range (IQR) | 59.0–75.3 | 62.0–81.0 | |
| Smoking | 3 (10.0) | 4 (12.9) | > 0.999 |
| Post decompression | 20 (66.7) | 24 (77.4) | 0.402 |
| Disease (index level) | 0.161 | ||
| DS | 20 (66.7) | 23 (74.2) | |
| FS | 7 (23.3) | 4 (12.9) | |
| CS | 2 (6.7) | 4 (12.9) | |
| DH | 1 (3.8) | 0 (0) | |
| Disease (adjacent level) | |||
| L3–4 segment | n= 13 | n= 48 | |
| Disc degeneration* | 0.238 | ||
| Grade 2 | 1 (7.7) | 2 (4.2) | |
| Grade 3 | 2 (15.4) | 20 (41.7) | |
| Grade 4 | 10 (76.9) | 25 (52.1) | |
| Grade 5 | 0 (0) | 1 (2.1) | |
| Facet degeneration† | 0.290 | ||
| Grade 0 | 3 (23.1) | 22 (45.8) | |
| Grade 1 | 7 (53.8) | 21 (43.8) | |
| Grade 2 | 2 (15.4) | 3 (6.3) | |
| Grade 3 | 1 (7.7) | 2 (4.2) | |
| Vacuum disc | 4 (30.8) | 12 (25.0) | 0.728 |
| Wedge deformity‡ | 1 (7.7) | 6 (12.5) | 0.999 |
| Spondylolisthesis§ | 0.756 | ||
| Anterior | 0 (0) | 1 (2.1) | |
| Retro | 3 (23.1) | 8 (16.7) | |
| L5-S1 segment | n= 21 | n= 40 | |
| Disc degeneration* | 0.709 | ||
| Grade 2 | 2 (9.5) | 9 (7.5) | |
| Grade 3 | 4 (19.0) | 12 (30.0) | |
| Grade 4 | 14 (66.7) | 21 (52.5) | |
| Grade 5 | 1 (4.8) | 4 (10.0) | |
| Facet degeneration† | 0.547 | ||
| Grade 0 | 11 (52.4) | 21 (52.5) | |
| Grade 1 | 9 (42.9) | 17 (42.5) | |
| Grade 2 | 0 (0) | 2 (5.0) | |
| Grade 3 | 1 (4.8) | 0 (0) | |
| Vacuum disc | 12 (57.1) | 14 (35.5) | 0.097 |
| Wedge deformity‡ | 0 (0) | 0 (0) | > 0.999 |
| Spondylolisthesis§ | 0.533 | ||
| Anterior | 1 (4.8) | 0 (0) | |
| Retro | 1 (4.8) | 3 (7.5) |
Values are presented as number (%) unless otherwise indicated.
ASD, adjacent segment disease; SD, standard deviation; IQR, interquartile range; BMI, body mass index; DS, degenerative spondylolisthesis; FS, foraminal stenosis; CS, central spinal stenosis; DH, lumbar disc herniation.
Chi-square test and Student t-test were used for statistical analysis.
Disc degeneration was graded according to the Pfirrmann grading system.
Facet degeneration was graded according to the Weishaupt classification system.
Wedge deformity was defined as >5° of tilt between the inferior margin of the upper vertebral body and the superior bone margin at the lower vertebral body in the coronal radiograph.
Spondylolisthesis was defined as >3 mm anterior or posterior vertebral slip on standing lateral radiographs.