Inter- and intrarater reliability of the head-shaft angle in children with cerebral palsy

TLDR: In this article, the inter-and intra-rater reliability of the head-shaft angle (HSA) on radiographs from a surveillance program for children with cerebral palsy (CP) was analyzed.

Abstract: Purpose The purpose of this study was to analyse inter- and intra-rater reliability of the Head-Shaft angle (HSA) on radiographs from a surveillance programme for children with cerebral palsy (CP). Method A high HSA is a risk factor for hip displacement in children with CP. To evaluate inter- and intra-rater reliability of the HSA, hip radiographs from the CP surveillance programme CPUP in the southern part of Sweden during the first half of 2016 were included in this study. Results We analysed 50 radiographs from children in Gross Motor Function Classification System (GMFCS) levels II-V with a mean age of 6.6 (SD 3.2) years from 11 different radiology departments. Three raters measured the HSA of one hip at baseline and after four weeks. Intra-Class Correlation Coefficient (ICC) showed excellent inter- and intra-rater reliability of the HSA with ICC 0.92 (95% CI 0.87–0.96) and ICC 0.99 (95% CI 0.98–0.99) respectively. Conclusion We conclude that the HSA, important when predicting hip displacement in CP, showed high inter-and intra-rater reliability when analysed on radiographs from various radiology departments in a surveillance program for CP.