Although Hip dysplasia is diagnosed using both clinical and sonographic findings, using ultrasound alone may over-diagnose DDH in the early days/ first week of life.
Bialik et al conducted a study to identify unstable newborn hips by ultrasound that matured in the first 6 weeks of life and eventually evolved became normal without treatment.
18,060 consecutive newborn hips underwent clinical and ultrasonographic exams at 1 to 3 days of life. Hips that had any type of sonographic abnormality were reexamined at 2 or 6 weeks, depending on the severity of the findings. Abnormal hips at six weeks of age were treated; all others were examined periodically until the age of 12 months.
There were 1001 instances of abnormal hips of the 18 060 newborn hips indicating a sonographic DDH incidence of 5.5% or about one in twenty. However, only 90 of the 1001 hips remained abnormal at six weeks and required treatment, indicating a true DDH incidence at six weeks of 0.5% or one in two hundred. All the others evolved into normal hips, and no additional instances of DDH were found on follow-up throughout the 12 months.
Clinicians and Parents have to be careful in interpreting the findings of ultrasonography performed in the first few days/ first week of life. When the examination of the baby at birth shows an unstable hip, then treatment is usually recommended. This study mainly looked at babies who had a normal examination and an abnormal ultrasound at the time of birth. This study supports the current practice of examination at time of birth, and then using the ultrasound at six weeks of age for hips that are at risk or when there is any concern by the parents of the doctor.