Table 1 Demographic and preoperative data

Age

48.19 ± 8.87

48.80 ± 9.98

0.847

Sex (male/female)

9/7

12/8

1.000*

Body mass index

24.97 ± 2.79

25.24 ± 2.98

0.691

ASA score

1.84 ± 0.36

1.83 ± 0.38

0.779

Level (%)

0.451†

 L3–4

1 (6.25%)

1 (5.0%)

 L4–5

10 (62.5%)

10 (50.0%)

 L5–S1

5 (31.25%)

9 (45.0%)

Direction, right/left (%)

10/6 (62.5%/37.5%)

12/8 (60.0%/40.0%)

0.883

Symptom-free period (months)

33.75 ± 23.56

33.45 ± 22.19

0.767