Table 1.

Demographic and clinical data of Patients (n = 113)

General data
Male: female	1:0.89
Age, mean ± SD (range)	37.4 ± 7.8 (23–68 yr)
Height, mean ± SD (range)	169.7 ± 6.2 (155–183 cm)
Weight, mean ± SD (range)	67.4 ± 8.7 (47–90 kg)
BMI, mean ± SD (range)	17.9 ± 5.22 (12–35)
Operation time	209.0 ± 29.1(170-300 min)
Bleeding volume	276.1 ± 77.1(100-500 mL)
One vertebral level N (%)	100 (88.5%)
Two vertebral levels N (%)	13 (11.5%)
L2-L3 N (%)	13 (11.5%)
L3-L4 N (%)	29 (25.7%)
L4-L5 N (%)	54 (47.9%)
L5-S1 N (%)	17 (15.0%)

BMI indicates body mass index, SD standard deviation