The use of X-ray at 5 months in a selective screening programme for developmental dysplasia of the hip

The methods used for any screening programme for developmental dysplasia of the hip (DDH) can be controversial. This was an opportunistic audit of our selective ultrasound screening programme using an X-ray at 5 months to prevent inappropriate discharge due to the learning curve of ultrasound.

Between 1990 and 2004 in Nottingham, UK, out of a total population of 108,500 births, approximately 11,500 neonates were screened using ultrasound. Any child with an ultrasound scan showing Graf α-angles greater than 60° (Graf Type I) with the hip in joint were discharged from the clinic. All of those discharged were subsequently X-rayed at 5 months in order to cover the learning curve of ultrasound. The X-rays were reviewed by a consultant radiologist and referred back to orthopaedics if there was lateralisation of the femoral head or an acetabular index above 30°.

Of approximately 11,000 X-rays performed, only 53 patients were referred back to orthopaedics, of which 47 had a complete data set. Of these 47 children, only 8 (17%) required intervention. On review of the original ultrasounds, Graf's α-angle did not seem to correlate well with the need for intervention, as all were Type I hips. The femoral head cover (FHC) appeared to be more predictive of the need for treatment. There have been no late presentations to our unit of DDH following a normal 5-month X-ray.

We now check the Graf α-angle, FHC and dynamic stability in the ultrasound assessment and only perform X-ray at 5 months if there was a low α-angle or low FHC. Since this change, there have been no late presentations of DDH from the population screened by ultrasound.