Table 4.
CSA (in mm²) of the multifidus muscle at the side of the disc herniation, is measured before surgery (CSA 1), and 1 year after surgery (CSA 2)
| Unilateral multifidus muscle | Tubular discectomy (N = 72) | Conventional microdiscectomy (N = 68) | P-value |
|---|---|---|---|
| CSA 1 (mm²) | 832 ± 206 | 817 ± 209 | 0.67 |
| CSA 2 (mm²) | 821 ± 238 | 846 ± 229 | 0.54 |
| CSA ratio | 0.99 ± 0.14 | 1.05 ± 0.19 | 0.04 |
| Mean multifidus atrophy score (0–3) | 1.22 ± 0.83 | 1.31 ± 0.78 | 0.64 |
| 0—normal | 14 | 11 | |
| 1—mild | 32 | 27 | |
| 2—moderate | 22 | 28 | |
| 3—severe | 4 | 2 | |
| Change in atrophy score | 0.65* | ||
| 0—constant | 62 (86%) | 56 (82%) | |
| 1—deteriorated (+1 point) | 10 (14%) | 12 (18%) | OR 1.3 (95% CI, 0.5 to 3.3)** |
The CSA ratio (CSA2/CSA1) represents the difference of cross-sectional muscle area within one patient. The mean multifidus atrophy score was calculated at 1 year after surgery, followed by the distribution in grade 0 to grade 3. Plus-minus values are means ± standard deviations
CSA cross sectional area; OR odss ratio; CI confidence interval
* Fisher exact test (2-sided)
** Odss ratio of atrophy deterioration in the conventional group versus tubular group