ARE PELVIC X-RAYS NECESSARY FOLLOWING A NORMAL ULTRASOUND IN THE SCREENING FOR DEVELOPMENTAL DYSPLASIA OF THE HIP?

Abstract

Introduction: Infants referred under the Hip Screening Programme undergo both a clinical and ultrasonic assessment of hip stability. The majority are reviewed for repeat clinical assessment and X-ray of the hips before a diagnosis of DDH will be excluded. If we could safely rely on the ultrasound findings, then the number of children routinely reviewed with a hip radiograph could be reduced. As a result, many children would avoid the unnecessary and potentially harmful exposure to radiation. In addition, the burden on both the Orthopaedic Outpatients Department and the Radiology Department could be eased.

Objective: The aim of the study was to assess the sensitivity of the ultrasound screening programme for DDH over a four year period.

Study Design: A retrospective review of the 501 infants referred for hip screening between January 1997 and December 2000.

Results: 28 patients were treated for DDH during the period of January 1997 to December 2000. Thirteen patients (46.4%) of those treated for DDH were referred via the Hip Screening Programme after their initial baby check by the paediatricians showed that they had a risk factor. The risk factors include Family History, Breech Deliver, and clinical instability. The remaining fifteen patients (53.6%) were referred via GP’s, Health Visitors and Paediatricians, following abnormal clinical findings ranging from ‘clicky hip’, abnormal skin creases, and decreased hip abduction at follow up baby checks. The average age of the infant in this group was 5.5 months. These 15 were diagnosed with X-ray only. All patients (501 patients) referred via the Hip screening programme underwent an ultrasound scan of both hips initially, and a pelvic X-ray 4–6 months after this. We identified 5 cases where the ultrasound had originally been interpreted as normal, yet the infant developed DDH as diagnosed by a later X–ray. Five infants (38.5%) of the thirteen diagnosed with DDH via the screening programme is unacceptable. These five infants could easily have been missed until they were a lot older, and subsequently their prognoses would have been worse.

Three (20%) of the fifteen patients diagnosed with DDH which were not referred via the Hip Screening Programme had an identifiable risk factor at birth, yet were not sent for orthopaedic review and ultrasound examination via the Screening Programme.

Conclusion: Normal ultrasound scan does not exclude a subsequent diagnosis of Developmental Dysplasia of the hip. X-ray is still considered the gold standard in assessing a child’s hips. Both the performance and interpretation of the hip ultrasound is skill with a steep learning curve and, for the meantime, will have to go hand in hand with pelvic X-rays in diagnosing DDH.