Ultrasound for hip dysplasia – disparities between community and tertiary paediatric services

Abstract

Objective

Explore the differences in ultrasound reporting between community ultrasound centres and a high-volume paediatric tertiary centre in diagnosing developmental dysplasia of the hip (DDH).

Participants

One hundred infants less than 6 months of age from a paediatric hip registry, who underwent ultrasounds in both community and tertiary centres within a 2-week interval.

Results

One percent of a 200-hip sample reported scan quality. Alpha angles were reported in 84.5% (n = 169) of community reports and 78.5% (n = 157) of tertiary centre reports. Femoral head coverage was reported similarly in both environments at 94.5% in community and 93.5% in tertiary. Beta angle appeared in 45% (n = 90) and 2% (n = 4), respectively. Bland Altman plots revealed that there existed variation in ultrasound interpretation especially in more dysplastic hips. The concordance correlation coefficient showed only moderate agreement (Rho = 0.60 for alpha angles, Rho = 0.61 for femoral head coverage), and interrater reliability on hip classification reached moderate agreement (Cohen's Kappa = 0.57 for alpha angle, and 0.45 for femoral coverage) between community and tertiary hospital reports.

Conclusions

Reliance on the community-acquired ultrasound report as a true reflection of the state of a hip is not completely justified. The lack of standardized reporting poses challenges for community clinicians in starting treatment or making appropriate referrals. Only a moderate agreement has been observed between the community and tertiary scans. Consequently, over 25% of hips classified as abnormal are potentially normal, and more than 15% dysplastic hips could be undetected.