Abstract
Aim: To assess if routine x-ray can be avoided following normal ultrasound in high risk screening for developmental dysplasia of the hip.
Methods: All children who had ultrasound as part of screening programme for developmental dysplasia of the hip during the period August 2006 and March 2007 were included for the study. After excluding 16 children due to incomplete details, either lack of clinical details/x-ray/ultrasound of the hip, 121 children were finally included for the study.
Results: Out of 121 children (242 hips), six of the hips were found to be dysplastic by ultrasound, average alpha angle being 43°, 2 of the hips turned out to be normal in subsequent X-rays. However three of the hips were found to be dysplastic in follow-up x-ray which was initially normal in the ultrasound, average alpha angle being 58.6°. The sensitivity in diagnosing developmental dysplasia of the hip by using α angle is 57% and 99% specific. The sensitivity did not improve by combining the alpha angle with percentage of femoral head coverage. Grafs α angle and percentage of femoral head coverage did not have any direct correlation with that of future acetabular index and hence routine x-ray still needs to be done to rule out developmental dysplasia of the hip.
Conclusion: Though the number of children involved in this study is small, three hips would have been missed if not followed up with x-ray, despite their percentage of coverage of femoral head being more than 50% and normal grafs α angle. Hence we recommend routine x-ray in the screening programme for developmental dysplasia of the hip despite initial normal ultrasound of the hip
Correspondence should be addressed to Mr Richard Wallace at Musgrave Park Hospital, 20 Stockman’s Lane, Belfast BT9 7JB, Northern Ireland.
