Table 3.

Comparison of the mean values of the individual disc height indices (DHI) for each lumbar spinal segment is presented. A paired sample t-test was used. The effect size was calculated using Cohen’s d. Significant p-values are marked in bold. The level of significance was set at p < 0.05

	Pre-operative	Post-operative	p-value	Cohen’s d
	Mean (± SD)	Mean (± SD)
DHI L1/2	20.7 (± 4.2)	21.5 (± 4.2)	< 0.001	0.302
DHI L2/3	21.5 (± 4.5)	22.5 (± 4.7)	< 0.001	0.422
DHI L3/4	22.2 (± 4.7)	23.5 (± 4.9)	< 0.001	0.477
DHI L4/5	22.8 (± 5.7)	24.4 (± 6.3)	< 0.001	0.406
DHI L5/S1	23.5 (± 7.2)	24.4 (± 7.6)	0.021	0.168