Material of 3.468 (6.936 hips) randomized cases of newborns, was sonographically and clinically examined during the two first days after birth with the aid of a 7,5 MHz linear transducer and a 5 MHz one for older babies in reexaminations. A standard plane of section was recorded by scanning (scale 1:1) and with this procedure documented a total number of 480 dysplastic hips (belonging to 395 newborns) indicating an incidence of 114 0/00. There is a difference of 64 0/00 between our findings (114 0/00) and the highest clinically diagnosed incidence (50 0/00), which has appeared in the international literature so far. This 64 0/00 theoretically indicates the cases with dysplastic hips that would go unnoticed without the help of sonography. These 480 dysplastic hips were classified (according to Graf) as following: IIa+ 328 (47,280/00), IIa- 6 (0,850/00), IIc 60 (8,650/00), D 38 (5,470/00), III 40 (5,750/00) and IV 10 (1,500/00). Pediatric clinical examination of hips revealed 10%, 12%, 5% and 50% dysplastic cases for the types IIc, D, III and IV respectively as expected. However orthopedic clinical examination revealed 40%, 60%, 70% and 100% dysplastic cases for each of the above mentioned types. It is obvious that the orthopedic examination with the aid of sonography is by far more reliable as regards DDH diagnosis and there is also a decrease in the frequencies of types that presented severe dysplasia when the newborns reexamined after treatment. At the end of the first trimester of life only six cases remained pathological (type II 5 cases and III one case).
