Table 2.

Intra- and Interobserver Reproducibility of the GAA in 20 Patients^a.

	Intraobserver reproducibility (Observer 1)	Intraobserver reproducibility (Observer 2)	Interobserver reproducibility
	ICC (95% CI)	ICC (95% CI)	ICC (95% CI)
LCEA	0.918 (0.867–0.976)	0.872 (0.832–0.987)	0.910 (0.835–0.965)
AI	0.913 (0.875–0.983)	0.921 (0.876–0.985)	0.916 (0.845–0.975)
FEAR Index	0.994 (0.982–0.999)	0.962 (0.863–0.992)	0.983 (0.893–0.996)
GAA	0.996 (0.994–1.0)	0.995 (0.907–0.994)	0.957 (0.890–0.988)

^aAI acetabular index, FEAR index Femoro-Epiphyseal Acetabular Roof, GAA Gothic Arch Angle, ICC intraclass correlation coefficient, LCEA Lateral Center–Edge Angle;