Evaluation of lateral and anterior center-edge angles according to sex and anterior pelvic plane tilt angle: a three-dimensional quantitative analysis

BACKGROUND: This study aimed to quantitatively evaluate lateral center-edge angle (LCEA) and anterior center-edge angle (ACEA) according to sex and the anterior pelvic plane (APP) tilt angle and analyze the correlation between these measurements and acetabular coverage. METHODS: Computed tomography scans of 71 adults (38 men and 33 women) with normal hip joints were obtained. LCEA, anterior ACEA, and acetabular coverage were measured with APP tilt every 5° from − 30° to + 30° and were compared between the sexes. The correlation between acetabular coverage and LCEA/ACEA was also analyzed. RESULTS: (1) LCEA, ACEA, and acetabular coverage were statistically larger in men than in women at all APP tilt angles (with the exception of acetabular coverage ≥ 25°). (2) LCEA, ACEA, and acetabular coverage differed according to APP tilt angle. LCEA and acetabular coverage showed maximum values at 10°. ACEA showed a tendency to increase by an average of 3.6° for every 5° increase in the APP tilt angle. LCEA demonstrated strong and very strong associations across all APP tilting angles, whereas ACEA showed a moderate association at angles ≥ 15° in men and ≥ 30° in women. CONCLUSIONS: The LCEA and ACEA are adequate measurement methods that reflect actual acetabular coverage unless the pelvis is tilted excessively anteriorly. While pelvic tilting does not need to be considered for LCEA within the physiologic range, it should always be taken into account for ACEA, as it increases by an average of 3.6° for every 5° increase in APP tilt angle. LEVEL OF EVIDENCE: Level III: retrospective cohort study.