The frontal pelvic plane provides a valid reference system for implantation of the acetabular cup: Spatial orientation of the pelvis in different positions

Figures & data

Figure 1. Pelvis model with the McKibbin's plane and the reference plane.

Figure 2. A. The settings for measurements in the standing position, highlighting the reference plane and the pelvic reference points. B. Photograph showing the settings for measurements in the supine position.

Figure 3. Measurements for the functionality of the tube roll.

Table 1.  Mean values and standard deviations of the pelvic inclination position

	Total mean (SD)	Group 1 mean (SD)	Group 2 mean (SD)	Group 3 mean (SD)	Group 4 mean (SD)	P-value	Adjusted p-value^a
Standing	6.7 (3.6)	5.2 (2.7)	6.2 (3.3)	6.7 (3.5)	8.7 (4.0)	0.004	0.05
Supine	5.6 (3.3)	6.2 (3.5)	4.4 (2.2)	6.1 (3.5)	5.7 (3.6)	0.1	0.08
Difference between supine and standing	−1.1 (4.8)	1.0 (4.3)	−1.9 (4.3)	−0.6 (4.6)	−3.0 (5.0)	0.007	0.1

^a Analysis of covariance was performed to adjust p-values for the effects of age and gender

Figure 4. The correlation between age and pelvic inclination in standing position.

Table 2.  Spearman's rank correlation between age, standing position, supine position and the difference between supine and standing

	Age		Standing		Supine		Difference^a
	rs	p-value	rs	p-value	rs	p-value	rs
Age	1
Standing	0.23	0.01	1
Supine	−0.059	0.5	0.011	0.9	1
Difference^a	−0.19	0.04	−0.71	<0.001	0.065	<0.001	1

^a Difference between supine and standing