The standard values for an infant hip exam vary depending on the age of the month and range from 80 to 170 degrees. In the case of ultrasound, the alpha angle is greater than 60 degrees and the beta angle is less than 55 degrees.
The α angle of the hip joint is the crossing angle obtained by the intersection of the bony acetabular line (the tangent line between the bone rim and the point of the lower edge of the ilium) and the parallel or tangent line of the body of the ilium bone; the β angle is the angle between the top of the soft acetabulum and the vertical axis, and the greater the angle is, the more unstable the joint is.
The purpose of the infant hip examination is to detect the extension of the hip joint. The standard values are 80-100 degrees from 0 to 3 months, 90-130 degrees from 4 to 6 months of age, 120-150 degrees from 7 to 9 months of age, and 140-170 degrees from 10 to 12 months of age.
Ultrasound can also be used to check the hip joint of infants, mainly checking the α angle and β angle, of which the normal value of the α angle should be more than 60 degrees and the normal value of the β angle is less than 55 degrees. It can provide a reference for determining whether there is congenital hip dislocation. If the value is within the normal range, it indicates that the infant’s hip joint is developing normally, and if it exceeds the normal value by a large amount, further examination is needed.
If parents suspect hip dysplasia, it is recommended to seek timely medical treatment.