The Use of a Horizontal Reference Line While Measuring the Anterior Center Edge Angle Is More Reliable Than the...

The anterior center edge angle (ACEA) is a radiographic parameter commonly utilized for the assessment of anterior acetabular coverage in the setting of various hip abnormalities. However, this measurement is greatly dependent on patient positioning and imaging technique.

To evaluate the utility of a measurement technique utilizing a horizontal reference line and femoral head perfect circles for better control of pelvic obliquity and the assessment of its potential as a more reproducible method for determining the ACEA.

Cohort study (diagnosis); Level of evidence, 3.

There were 3 authors who retrospectively reviewed the false-profile radiographs of 21 patients. Traditional ACEA measurements and novel ACEA measurements utilizing a horizontal reference line and best-fit circles on each femoral head were recorded by each author on 2 separate occasions. A paired t test was used to establish the difference between traditional and novel measurements for each reviewer. The intraclass correlation coefficient (ICC) was used to determine interrater and intrarater reliability across both methods. Significance was set at P < .05.

The mean ACEA value obtained using the traditional method was 39.72°, and the mean ACEA value obtained using the novel method was 37.68° (P = .36). Intrarater reliability for the novel method was found to be strong (ICC = 0.805-0.966) in all instances. Interrater reliability was found to be strong in all instances utilizing the horizontal reference line (ICC = 0.831-0.902) but was weak for 2 of 3 reviewers using the traditional method (ICC = 0.420, 0.585, and 0.769).

The novel method of measurement was found to have strong agreement within each reviewer across both measurement attempts as well as between all 3 physician reviewers. The traditional method was found to have weak intrarater reliability for 1 of 3 physician reviewers and weak interrater reliability for 2 of 3 reviewers. These results demonstrate that the novel method was more reproducible across individual reviewers and between different reviewers. As such, consideration should be given to utilizing the novel method for measuring the ACEA as a standardized technique in future research efforts on hip dysplasia and femoroacetabular impingement.