Table 3.

Bare window width analysis according to age group

Age group [n]	L2–L3	L3–L4	L4–L5
< 40 years [n = 173]	1.32 ± 0.35	1.20 ± 0.33	0.46 ± 0.41
40–60 years [n = 97]	1.43 ± 0.39	1.33 ± 0.38	0.74 ± 0.47
> 60 years [n = 37]	1.63 ± 0.45	1.49 ± 0.50	1.04 ± 0.59
P value	< 0.001	< 0.001	< 0.001

All values are mean ± SD [cm]; n, number of cases in each age group

Difference of Bare window width at L2–3: < 40 versus 40–60 (p = 0.03); 40–60 versus > 60 (p = 0.007); < 40 versus > 60 (p =  < 0.001)

Difference of Bare window width at L3–4: < 40 versus 40–60 (p = 0.007); 40–60 versus > 60 (p = 0.032); < 40 versus > 60 (p =  < 0.001)

Difference of Bare window width at L4-5: < 40 versus 40–60 (p =  < 0.001); 40–60 versus > 60 (p = 0.001); < 40 versus > 60 (p =  < 0.001)