THE USE OF X-RAY AT FIVE MONTHS IN THE SCREENING FOR DDH

Abstract

Purpose of study: To assess whether a plane x-ray at five months is needed in a DDH screening program.

Method: Between 1990 and 2004 we operated selective hip screening, including ultrasound. Hips screened as normal had an X-ray at 5 months, initially instituted to cover the ultrasound learning curve. These were reported by a consultant radiologist and referred if thought abnormal. For the purposes of this study the notes, scans and X-rays of all patients referred at 5 months were reviewed.

Results: In Nottingham there were approximately 108,500 births between 1990 and 2004. Of these 11,425 were referred for ultrasound scan. 53 were referred to orthopaedics following the x-ray at 5 months. 47 of these had a complete data set. Of these 47 children, 30 (64%) were watched, 9 (19%) had arthrograms only, 5 (11%) had adductor tenotomy and application of a hip spica. One (2%) child had Pavlik harness treatment and 2 (4%) had a femoral osteotomy.

Graf’s alpha angles and percentage cover were reviewed from the original ultrasounds, many of which were of poor quality. This demonstrated that there was less than 50% cover for 14/30 (47%) who were watched, for 6/9 (78%) who had arthrograms, for 1/1 (100%) treated by harness, for 4/5 (80%) treated with adductor tenotomy and hip spica and for 2/2 (100%) requiring surgery. Alpha angles less than 60 degrees did not predict the need for intervention. There were no late cases from the group that had X-rays classed as normal at 5 months.

Conclusions: The importance of measuring head cover was established and is now routine in the hip instability clinic. It was clear that a large population had received unnecessary X-rays. X-rays are now only performed if US at 6 weeks reveals a low alpha angle or less than 50% cover.