Table 1.

Comparison of preoperative and postoperative mean values of standing and sitting lumbar lordosis (LL) and the difference between standing and sitting represented by ΔLL. Student’s t-test for related samples was applied. The effect size was calculated using Cohen’s d. Significant p-values are marked in bold. Level of significance set at p < 0.05. SD standard deviation

	Preoperative	Postoperative	p-value	Cohen’s d
	Mean (± SD)	Mean (± SD)
LLsitting [°]	29.4 (± 15.4)	26.7 (± 15.4)	0.01	0.186
LLstanding [°]	51.3 (± 14.3)	52.4 (± 13.8)	< 0.001	0.259
ΔLL [°]	22.0 (± 12.3)	25.9 (± 12.3)	< 0.001	0.367