Limitation of abduction of hips in the newborn. Is it a clinical sign or a phenocopy of congenital hip dislocation?

Until recently the possibility of a connection between maternal thyroid disorders and congenital hip pathology in the newborn has not been given any attention. However, from this study it is evident that there is a close relationship between maternal thyroid disorders and limitation of abduction of the hips in the newborn. The histological findings are suggestive of a neonatal thyrotoxic myopathy or periodic paralysis which might give rise to an error in muscle balance around the hips. The high proportion of affected children without a family history of congenital hip dislocation suggests that genetic factors have in the past been overemphasized.