Fig. 2

Bar charts represent the mean and standard deviation (SD) of different measurements. a Angle characteristics in male and female groups (mean ± SD). b Angle characteristics in 18–30, 30–50, > 50 years-old age groups (mean ± SD). c Angle distribution in < 0°, 0°–5°, 5°–10°, 10°–15°, 15°–20°, 20°–25°, 25°–30°, > 30° groups. d Angle characteristics in different sex and age groups (mean ± SD)