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Ultrasound screening for decentered hips in children with severe cerebral palsy: a preliminary evaluation
Igor Šmigovec1, Tomislav Ðapić, Vladimir Trkulja
1Department of Orthopedic Surgery, University Hospital Center Zagreb, Zagreb University School of Medicine, Šalata 6, 10000, Zagreb, Croatia, ortopedija@yahoo.com.
Insights
Ultrasound (US) reliably screens for hip instability in children with cerebral palsy, reducing the need for X-rays and radiation exposure. This diagnostic tool shows high sensitivity and negative predictive value for detecting decentered hips.
Area of Science:
- Pediatric Orthopedics
- Diagnostic Imaging
- Cerebral Palsy Management
Background:
- Standard hip surveillance for cerebral palsy relies on serial X-rays.
- Ultrasound (US) is established for developmental hip dysplasia screening.
- Children with cerebral palsy require effective hip monitoring due to high risk of displacement.
Purpose of the Study:
- To assess the diagnostic accuracy of ultrasound (US) for screening decentered hips in children with cerebral palsy.
- To evaluate US lateral head distance as a predictor of hip migration percentage.
- To determine if US can replace or reduce radiographic assessments in this population.
Main Methods:
- Prospective, single-center, assessor-blind diagnostic study.
- Included 100 children (2-8 years) with cerebral palsy and severe motor disability.
- Compared ultrasound (US) lateral head distance with X-ray migration percentage (≥0.33 threshold).
Main Results:
- Ultrasound demonstrated high accuracy in detecting decentered hips (ROC curves 92-99%).
- Sensitivity for detecting hips needing treatment was excellent (95.5-100%).
- Negative predictive value was very high (98.5-100%), indicating reliable exclusion of pathology.
Conclusions:
- Ultrasound is a reliable tool for screening decentered hips in children with cerebral palsy.
- US can significantly decrease the reliance on repeated X-rays, reducing cumulative radiation dose.
- This approach enhances diagnostic efficiency and patient safety in managing hip instability in cerebral palsy.
Background:
Ultrasound (US) is routinely used for hip screening in children with developmental hip disorders, whereas standard hip surveillance in children with cerebral palsy is based on repeated X-ray assessments.
Objective:
To evaluate US as a diagnostic tool in screening for decentered hips in children with cerebral palsy.
Materials And Methods:
We conducted a prospective, diagnostic single-center assessor-blind study that included consecutive children (age 2-8 years) with cerebral palsy and severe motor disability who underwent US and X-ray hip assessment. US lateral longitudinal scans were used to determine lateral head distance. X-ray assessment was used to determine migration percentage. Diagnostic properties of lateral head distance in detecting hips with a migration percentage ≥0.33 (which requires preventive treatment) were evaluated overall (n = 100) and for hips assessed at the age 24-60 months (n = 38) or >60 to ≤96 months (n = 62). Fifty hips underwent US assessment by two investigators to evaluate inter-rater reliability and agreement.
Results:
Prevalence of migration percentage ≥0.33 was 22.0% overall and 26.2% and 19.4% in the younger and older age-based subsets, respectively. Lateral head distance well discriminated hips with a migration percentage ≥0.33 (areas under the receiver operating characteristics [ROC] curves 94%, 99% and 92%, respectively). At the optimum cut-off values of lateral head distance (5.0, 5.0 and 4.8 mm, respectively), sensitivity was 95.5%, 100% and 100% overall and in the two age-based subsets, respectively, whereas specificity was 85.9%, 96.4% and 72.0%, respectively. Consequently, positive predictive value was relatively low, but negative predictive value was 98.5% (95% CI 92.1-100) overall and 100% (97.5% one-sided CI 87.2-100) and 100% (97.5 one-sided CI 90.2-100) in the two age-based subsets, respectively. Inter-rater reliability was high (intraclass correlation coefficient = 0.98, 95% CI 0.97-0.99) and 95% limits of agreement were reasonably narrow (-1.203 mm to 0.995 mm).
Conclusion:
In children with cerebral palsy, US can be reliably used in screening for decentered hips and can greatly reduce the need for repeated radiographic assessments, thus reducing radiation burden in these children.
