Table 2.

Comparisons of preoperative, postoperative, final follow-up AI, and ΔAI of the PFO and non-PFO groups, ° Mean, (range; SD), M (Q1; Q3).

Group	No. of hips	Preoperative AI	Postoperative AI	Final follow-up AI	ΔAI (postoperative – final follow-up)
PFO group	31	37.7 (22–50; 6.4)	20.0 (7–39; 8.2)	13.0 (8.0; 20.0)	5.6 (−15 – 24; 9.0)
Non-PFO group	28	38.0 (29–51; 6.0)	27.9 (10–42; 7.5)	24.5 (20.3; 27.8)	4.7 (−3 – 13; 4.6)
t/Z value		0.241	3.851	−4.012*	−0.492
P value		0.810	<0.001	<0.001	0.625

Note: AI: acetabular index; preoperative AI, postoperative AI, and ΔAI were compared using the independent samples t-test; final follow-up AI was compared using the Mann–Whitney U test; *: Z value.