# Association Between Alpha Angle and Acetabular Index in Screening for Developmental Dysplasia of the Hip

## TL;DR

This study explores the link between alpha angles and acetabular indices in infants to improve early detection of hip dysplasia.

## Contribution

The study identifies a significant correlation between alpha angles and acetabular indices in six-month-old infants for hip dysplasia screening.

## Key findings

- An increase in the left hip alpha angle correlates with a decrease in the left hip acetabular index (p=0.015).
- A significant relationship was found between the right hip alpha angle and acetabular index (p=0.017).
- Alpha angles greater than 70° are suggested as reliable indicators of normal hip health.

## Abstract

Background: Developmental dysplasia of the hip (DDH) is a critical orthopedic condition ranging from minor hip joint instability to complete dislocations, demanding early intervention to avoid severe complications, especially in children. In Mexico, stringent regulations under the Norma Oficial Mexicana (NOM) mandate hip screening for pediatric patients. The primary objective of this study is to investigate the relationship between alpha angles and the acetabular index in patients at six months of age, aiming to determine whether an increase in the alpha angle correlates with a better acetabular index.

Methods: We included 120 patients who were screened for hip issues with Graf's methodology in June 2023 and September 2023 at the General Hospital of Mexico "Dr. Eduardo Liceaga" in Mexico City before three months of age and attended their follow-up appointment at six months of age, where acetabular index measurement was performed using the Carestream platform on institutional X-rays.

Results: In our statistical analysis, we obtained a statistically significant relationship between an increase in the left hip alpha angle and a decrease in the left hip acetabular index (p=0.015) although it was not significant for an acetabular index of less than 25° (p=0.055). A significant relationship was observed between the right hip acetabular index and the right hip alpha angle (p=0.017) but not significant for an acetabular index less than 25° (p=0.10).

Conclusion: Universal hip screening is crucial for the early detection of DDH. Our study emphasizes using alpha-angle measurements (>70°) as reliable indicators of normal hip health.