Hemispheric cups do not reproduce acetabular rim morphology

Figures & data

Figure 1. The frontal pelvic plane and the pelvic coordinate system as deined by four anatomical landmarks on the pelvis, the anterior superior iliac spines (ASIS) and the pubic tubercles (PT).

Figure 2. An acetabular rim shown as a two-dimensional profile using cylindrical coordinates.The anatomical landmarks identified on the acetabular rim are the posterior inferior horn (PIH), anterior inferior horn (AIH), and inferior margin of the acetabular notch (IMAN).The depth of the psoas valley is the difference between the average heights of adjacent peaks (P1 and P2) and the height of the central trough (T).

Figure 3. Superposition of acetabular rim profiles with an eighth-order mean polynomial curve and the 95% confidence bands.

Table 1.  Acetabular morphometric data and sex-related variation

Parameter	Total group (n=68)	Male (n=26)	Female (n=42)	P-value
Acetabular diameter (mm)	48.9 (4.6) (40.1–57.6)	52.8 (2.9) (48.0–57.6)	46.5 (3.6) (40.1–57.0)	< 0.001
Depth of psoas valley (mm)	3.8 (2.0) (0.1–8.4)	4.7 (2.2) (1.2–8.4)	3.2 (1.6) (0.0–7.1)	< 0.01
Width of psoas valley(°)	71.0 (18) (24–131)	72.7 (11) (59–92)	70.4 (20) (24–131)	> 0.1
Acetabular anteversion (°)	20.9 (9.1) (−4.6–45.1)	15.7 (8.8) (-4.6–27.8)	24.1 (7.8) (12.1–45.2)	<0.01
Acetabular inclination(°)	40.7 (4.4) (31.4–51.6)	41.0 (4.8) (33.2–51.6)	40.5 (4.3) (31.4– 48.3)	>0.1

Values are expressed as mean (SD) (minimum–maximum)