Table 3.

Omega zone in percentage of femoral head circle

Omega zone	FAI		C-high ≥ 55°				C-low < 55°
Flexion	Mean	95% CI	Mean	95% CI	p value*	d	Mean	95% CI	p value*	d
0°	18	15–22	23	19–27	0.017	−0.55	23	20–27	0.069	−0.86
30°	16	11–20	22	19–26	0.004	−0.82	23	20–27	0.027	−1.11
60°	12	7–17	20	18–22	0.004	−0.97	23	19–26	0.008	−1.31
90°	9	4–13	16	13–19	0.007	−0.87	19	17–22	0.003	−1.50

* Compared with FAI; FAI = femoroacetabular impingement; C-high = subjects with alpha angle ≥ 55°; C-low = subjects with alpha angle < 55°; for the post hoc Mann-Whitney U test, significance level was set at p < 0 .017 with Bonferroni correction; d = Cohen’s d effect size.