The natural history of abnormal ultrasound findings in hips of infants under six months of age

PURPOSE: To collect and describe data on the natural history of abnormal ultrasound (US) findings in hips of infants under six months of age to serve as a reference to the design of screening programmes and treatment algorithms in the care for children with hip dysplasia. METHODS: A search in PubMed of the terms “DDH” and “ultrasound” was done to find hips with abnormal US findings that were not treated. In cases of multiple periods of follow-up, the classification of every period was evaluated separately (individual hip follow-up periods). RESULTS: Data of 13 561 hips with 16 991 follow-up periods were collected and analyzed. Most quantifiable classifications and follow-up periods were according to Graf (14 876) and a minor number of the hips had follow-up periods with femoral head coverage (FHC) (2115). Normal development without treatment in the first six months was for Graf 2a between 89% and 98%, for Graf 2c between 80% and 100% and for clustered data Graf 2a to 2c between 80% and 97%. For Graf 3 hips more than 50% were reported to develop into normal hips without treatment. As for Graf 4 hips this percentage was reported below 50%. For children with an FHC less than 50%, normalization was reported between 78% and 100%. CONCLUSION: The natural history of developmental dysplasia of the hip (DDH) shows a benign course, especially in the well-centered hips. This outcome probably contributes to the fact that all studies on US screening of hips for detection of relevant DDH in order to improve outcomes of treatment are rated as substantially underpowered.