[Does the IIa hip need treatment? Results of a longitudinal study of sonographically controlled hips of infants less than 3 months of age].

In a randomized retrospective study we followed hips classified as Type II a by ultrasound. The classification as "Type IIa" only was found inadequate. It is important to further differentiate the so-called physiologically immature hip, namely to distinguish between joints that, while immature, are appropriate for age [Type IIa(+)], and those hips with a maturation deficit exceeding a tolerable degree [Type IIa(-)]. The follow-up showed that hips classified as Type IIa(-) and treated before the age of 6 weeks had a clearly better healing result than the hips treated only after the sixth week. Thus, to achieve optimal healing and to keep to a minimum the dysplasias requiring treatment after 3 months' age, an ultrasound study of the hip should be done as early as possible. The total percentage of ultrasonically recognized abnormal joints requiring treatment (independently of the patient's age) was 6.6%. This corresponds to the regional average before the advent of ultrasound. However, because of extensive very early screening in our area, we found not a single hip dislocation later then at the age of 10 weeks during the last 2 years.