Sonographic image of the newborn hip with positive Ortolani's sign

In a screening program, 4438 newborns were examined sonographically and clinically in the first 12 hours after birth for congenital hip dysplasia. Seventy-three hips in 54 newborns were dislocated, as evidenced by positive Ortolani's signs. According to Graf's classification, all 73 hips should be Type IIC or worse, with Angle alpha less than 50 degrees and Angle beta for Type IIC of 72 degrees-77 degrees, and for Types D, III, and IV, greater than 77 degrees. Sonographic examination of the 73 hips according to Graf's criteria showed that only 16 hips were decentring and eccentric, confirming the clinical diagnosis, and the results were consistent with Graf's conclusion because their alpha-angles were less than 50 degrees and beta was greater than 77 degrees. In the remaining 57 hips, there was a disparity between alpha-angles and beta-angles. Judging by Angle alpha, these hips were of Types IB and IIA because their Angle alpha averaged 60.8 degrees (range, 51 degrees-74 degrees). Judging by Angle beta, these hips were decentring Type D or eccentric Type IIIA because their beta-angle averaged 91.3 degrees (range, 78 degrees-110 degrees). Because these 57 hips were dislocated clinically (positive Ortolani's sign) it was concluded that the beta-angle is a more accurate reflection of hip pathology in the newborn than the alpha-angle. It represents the cartilaginous roof of the acetabulum, which is soft and malleable, and reflects immediately any change in the position of the femoral head. Angle alpha, however, represents the hard bony roof, and any change in the position of the femoral head is not reflected immediately on it, because bony changes take longer to be seen or evidenced.