[Secondary flattening of the acetabular roof in children].

The primary "idiopathic" shallow acetabuli within the classical complex of CDH are confronted with the rare secondary "symptomatic" dysplasias of the acetabular roof. They are encountered mainly in connection with neuromuscular diseases and bad static conditions about the hip-joint. Nine cases with secondary flattening of the acetabular roof of unknown aetiology are presented, probably partially due to CDH, in connection with slight cerebral disturbances, mental and physical retardation, hypotonia of the muscles, with general constitutional laxity of joints as well as with acquired local loosening of the joint capsule due to treatment, and with insufficiency of the hip-abductors. As with the classical CDH one may observe in those cases a lateralization of the femoral head in the absence of an interposition in the joint; increasing subluxations due to joint instability with increasing shallow acetabuli may start from infancy, many years prior to puberty. If conservative treatment--not prolonged--fails and the findings are deteriorating acetabuloplasty is indicated prior to intertrochanteric adduction osteotomy during the growth-period.