[A clinical and genetic study on the congenital dislocation of the hip].

Among 13,779 infants examined from 1974 to 1980 at Takashimadaira and Toride health centers, there were 45 patients with congenital hip dislocation, an incidence of 3.3 per 1,000 live births, that is, 0.08% and 0.53% respectively in male and female. The male to female ratio was 1: 7.4. Its incidence seems to be decreasing year by year with statistic significance, compared with the data previously reported. A family study was conducted based upon 117 patients with this disease diagnosed at the Tokyo Medical and Dental University from 1971 to 1980. Applying the recurrence rate of siblings and the incidence in the general population to the model proposed by Falconer, the heritability of liability to congenital hip dislocation in Japan is estimated to be 80 +/- 20% in males and 135 +/- 10% in females, which is beyond limitation of the heritability and much higher than Woolf's estimation (82% in male and 58% in female). This might be due to the insufficient size of the test population, but the genetic factors are presumed to play a more important role on the etiology of this abnormality.