Differences between the alpha angles measured manually and digitally from paediatric hip ultrasonograms

The aim of this study was to reveal whether a meaningful difference is caused by measuring the alpha angle in hip ultrasonography manually or digitally to help the early diagnosis and treatment of DDH and observe the treatment implications of any such difference. All ultrasound images were obtained by same orthopaedist, and each hip was measured twice by two investigators with different levels of experience. Standard images were taken, and a printout of the standard images were obtained. The alpha angle was measured digitally by using the sonography device. The alpha angle was also measured by pencil, ruler and goniometer on the printout after 2 days. One hundred and two hips of 51 babies, at a mean age of 14 weeks, were assessed. The mean alpha angle measured manually with a goniometer was 64.4° (±1.6°), while that measured on the ultrasonography device was 65.3° (±0.9°). This difference was found to be statistically different (p = 0.016). Typology changes occurred in a total of 10 hips out of 102 as a result of manual and digital measurements. However, this study showed reduction in alpha angle variation and considerable advantages for manual alpha angle measurement with pencil and goniometer on a printout compared to computer-based measurement; future studies are needed to understand these differences caused by each measurement method.