Utility of routine X-ray surveillance following hip sonography for developmental dysplasia in children: a single-center study spanning a decade

Introduction: This study evaluates the necessity of routine X-ray follow-ups in children with developmental dysplasia of the hip (DDH), identified through Graf hip ultrasound, a standard component of screening in Germany. The purpose of this study was to investigate the occurrence of radiological deterioration in hips that were initially diagnosed and treated according to established guidelines within a university-based risk-enriched cohort and to identify associated risk factors.

Materials and methods: Patients diagnosed with developmental DDH from 2009 to 2018 with sonographically healthy hips (alpha > 64°) post conservative therapy and at least one follow-up X-ray by the age of two were analysed. Patients with significant comorbidities, syndromes, malformations, non-compliance with treatment, or missing X-ray data were excluded. Descriptive analysis of sonography, X-ray, and patient records were followed by univariate analysis and subsequent multiple logistic regression, identifying risk factors for severe and extreme dysplasia in X-rays.

Results: Of the 450 included hips, 254 were classified as Graf Type 2a or higher, leading to treatment. Subsequent X-rays revealed severe dysplasia in 53 hips and extreme dysplasia in seven hips. Univariate analysis identified sex, initial Graf-Type, therapy type and duration as significantly associated with pathological radiographs. A regression model identified the initial Graf type as the predominant predictor with hip types 3a and 4, cast therapy and overhead extension as independent predictors.

Conclusions: The data demonstrate pathological findings even after successful conservative treatment of DDH. Worsening of X-ray findings appear less frequent in mild dysplasia. These insights support routine radiographic follow-up assessments after successful conservative therapy. However, further dedicated studies are needed to determine whether patients with initially normal radiographs require radiographic follow-up.