Table 3.

Comparison of the mean contact area (in mm²) among the three pelvic positions

Group	Standard positiona	Supine position			Standing position
	Mean ± SD	Mean ± SD	Mean difference (95% CI)b	p valueb	Mean ± SD	Mean difference (95% CI)c	p valuec
Hip dysplasia (n = 32)	484 ± 96	581 ± 117	96 (43-150)	< 0.001	490 ± 128	5 (-51 to 62)	> 0.99
Control (n = 16)	954 ± 113	1094 ± 100	140 (63-217)	< 0.001	919 ± 121	-35 (-119 to 49)	0.93
p valued	< 0.001	< 0.001			< 0.001

^aStandard pelvic position was defined as that where the CT scanner coordinate system matches the anterior pelvic plane coordinate system.

^bSupine versus standard position.

^cStanding versus standard position.

^dHip dysplasia versus control group.