# Ultrasound is a suitable radiation-free alternative for hip surveillance in children with cerebral palsy or developmental dysplasia of the hip older than one year

## TL;DR

This study shows that ultrasound can reliably detect hip issues in children with cerebral palsy or hip dysplasia, offering a safer alternative to X-rays.

## Contribution

The study demonstrates that ultrasound is a radiation-free and reliable alternative to radiography for hip surveillance in children with CP or DDH.

## Key findings

- Ultrasound migration indices correlated well with radiographic indices, showing high reliability.
- Ultrasound parameters showed significant differences between DDH and CP patients.
- Using ultrasound reduces radiation exposure while maintaining diagnostic accuracy.

## Abstract

Children with chronic diseases are at a significant risk of radiation exposure. This cohort study evaluates the effectiveness and reliability of ultrasonography (US) for detecting femoral head decentration in children with cerebral palsy (CP) and developmental dysplasia of the hip (DDH), comparing it with traditional radiographic techniques to reduce radiation exposure.

A total of 169 patients were enrolled in the study. Both hips were evaluated in 158 patients, resulting in a total of 327 hips. Patients underwent clinical and radiological assessments, including standardized US. Parameters measured included the ventral and lateral bony and cartilaginous ultrasonographic migration indices (bUMI and cUMI), which were compared with standardized radiographic indices (Reimers index (RI) and extrusion index (EI)).

The lateral bUMI (17.4%) was significantly lower than the lateral cUMI (25.9%). RI values were lower than EI values (16.8% vs. 27.7%). No significant differences were observed between the bUMI and RI, or between the cUMI and EI, indicating the reliability of US. All lateral parameters correlated well with the lateral centre-edge angle (LCE). Positive correlations were found between the lateral cUMI and the radiological indices, with high inter- and intra-rater reliability (ICC). Significant differences in lateral and ventral UMIs were noted when comparing DDH and CP patients.

US is a reliable alternative to radiography for hip surveillance in detecting hip decentration in children with CP and DDH. It reduces radiation exposure while maintaining diagnostic accuracy. The findings support the adoption of US in clinical practice to improve early diagnosis and intervention.

The online version contains supplementary material available at 10.1007/s00264-025-06701-2.