Anatomical relationships of human pelvises and their application to registration techniques

Figures & data

Table I.  Number of observations and separation into subgroups.

		Source			Condition		Origin
	Total	Pre-op	Post-op	Cadaver	Normal	Abnormal	Asia	RoW	US
Female	246	139	80	27	144	102	57	159	30
Male	174	84	57	33	109	65	12	143	19
Total	420	223	137	60	253	167	69	302	49

Figure 1. Planning of the pelvic landmarks, including the deepest point in each fossa, performed with iPlan 3.0 software (Brainlab AG).

Figure 2. Alternative reference planes RP₁ (ASIS-ASIS-CoR) and RP₂ (ASIS-ASIS-Fossa) to define the sagittal orientation of the pelvis. The distance between the anterior rim point and the APP is also shown: This distance was used to define RP₃.

Figure 3. Measurement of the inter-teardrop distance (ITD). The measurement was performed virtually based on digitally reconstructed radiographs (DRRs) with iPlan 3.1 prototype software (Brainlab AG).

Table II.  Summary of statistics (mean ± standard deviation) for anatomical relationships used in the proposed pelvis registration method.

	Inter-fossa distance (IFD) (mm)	Deviation APP vs. RP1 (CoR) (°)	Deviation APP vs. RP2 (fossa) (°)	Deviation APP vs. RP3 (anterior rim) (°)	Deviation APP vs. RP4 (RP1 to RP3) (°)
Total	121.3 ± 9.0	37.5 ± 4.8	42.5 ± 4.4	0.3 ± 4.6	0.4 ± 3.8
Female	124.9 ± 8.5	37.6 ± 5.0	42.6 ± 4.5	0.3 ± 5.0	0.3 ± 4.0
Male	116.2 ± 7.0	37.3 ± 4.6	42.2 ± 4.3	0.2 ± 4.0	0.4 ± 3.5
Normal	120.6 ± 9.0	37.7 ± 4.7	42.9 ± 4.4	−0.6 ± 3.9	−0.1 ± 3.6
Abnormal	122.4 ± 8.9	37.2 ± 5.0	41.8 ± 4.3	1.5 ± 5.2	1.1 ± 4.0
Asia	120.5 ± 8.2	37.8 ± 4.4	43.2 ± 4.2	2.0 ± 4.9	0.7 ± 3.8
RoW	121.5 ± 9.2	37.4 ± 4.9	42.2 ± 4.4	0.1 ± 4.3	0.4 ± 3.8
US	121.4 ± 8.8	37.6 ± 4.8	42.8 ± 4.7	−1.4 ± 4.9	−0.2 ± 4.1

Table III.  Summary of statistics (mean ± standard deviation) for the deviation between the gold-standard APP and lateral registration, assuming a standard cup position (40° inclination, 15° anteversion).

	Error in inclination (°)	Error in anteversion (°)
Total	0.15 ± 2.86	0.27 ± 3.46
Female	0.18 ± 3.05	0.27 ± 3.60
Male	0.11 ± 2.58	0.25 ± 3.26
Normal	−0.07 ± 2.69	−0.18 ± 3.15
Abnormal	0.49 ± 3.07	0.94 ± 3.80
Asia	−1.21 ± 2.69	0.03 ± 3.33
RoW	0.53 ± 2.87	0.39 ± 3.51
US	−0.25 ± 2.40	−0.19 ± 3.35