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3D ultrasound to quantify lateral hip displacement in children with cerebral palsy: a validation study
Rebecca H Kay1,2, Jonathan J Noble2, Liam Johnston1,3
1Biomedical Engineering and Imaging Sciences, King's College London, London, UK.
Insights
Lateral head coverage (LHC), a new index from 3D ultrasound, accurately assesses hip dysplasia in children with cerebral palsy (CP). It shows strong correlation and reliability comparable to the established Reimer's migration percentage (RMP).
Area of Science:
- Pediatric Orthopedics
- Medical Imaging
- Cerebral Palsy Research
Background:
- Hip dysplasia is a common complication in children with cerebral palsy (CP).
- Accurate monitoring of hip development is crucial for managing CP-related orthopedic issues.
- Existing methods like Reimer's migration percentage (RMP) have limitations.
Purpose of the Study:
- To validate a novel index, lateral head coverage (LHC), for assessing hip dysplasia in children with CP.
- To evaluate the reliability and correlation of LHC with the established RMP.
- To explore the utility of 3D ultrasound in monitoring hip development in this population.
Main Methods:
- Prospective recruitment of 22 children (age 4-15) with CP undergoing routine hip surveillance.
- Comparison of 3D ultrasound-derived LHC measurements with planar radiograph-based RMP.
- Assessment of LHC repeatability and inter/intra-assessor reliability using intraclass correlation coefficients.
Main Results:
- Lateral head coverage (LHC) demonstrated a strong negative correlation with Reimer's migration percentage (RMP) (Spearman's rho = -0.86, p<0.001).
- LHC exhibited high inter-assessor reliability (ICC=0.97) and intra-assessor reliability (ICC=0.98), comparable to RMP.
- 3D ultrasound is a viable tool for measuring LHC in children with CP.
Conclusions:
- Lateral head coverage (LHC) is a valid and reliable index for assessing hip dysplasia in children with cerebral palsy.
- 3D ultrasound offers a promising approach for hip surveillance in children with CP, with LHC being a comparable alternative to RMP.
- This initial validation supports the use of LHC and 3D ultrasound in clinical practice for monitoring hip development in pediatric CP.
Aim:
To assess the validity of a new index, lateral head coverage (LHC), for describing hip dysplasia in a population of children with cerebral palsy (CP).
Method:
LHC is derived from 3D ultrasound assessment. Twenty-two children (15 males, seven females; age 4-15y) with CP undergoing routine hip surveillance were recruited prospectively for the study. Each participant had both a planar radiograph acquired as part of their routine care and a 3D ultrasound assessment within 2 months. Reimer's migration percentage (RMP) and LHC were measured by the same assessor, and the correlation between them calculated using Pearson's correlation coefficient. The repeatability of LHC was investigated with three assessors, analysing each of 10 images three times. Inter- and intra-assessor variation was quantified using intraclass correlation coefficients.
Results:
LHC was strongly correlated with RMP (Spearman's rank correlation coefficient=-0.86, p<0.001). LHC had similar inter-assessor reliability to that reported for RMP (intraclass correlation coefficient=0.97 and intra-assessor intraclass correlation coefficient=0.98).
Interpretation:
This is an initial validation of the use of 3D ultrasound in monitoring hip development in children with CP. LHC is comparable with RMP in estimating hip dysplasia with similar levels of reliability that are reported for RMP.
