However, in infants this line can be unreliable as it depends on the rotation of the hip when the image is taken. In children over about 3 to 4 years of age, this line should be smooth and undisrupted, otherwise it may indicate a fracture or hip dysplasia. (C) Shenton line is a continuous arc drawn from the inner edge of the femoral neck to the superior margin of the obturator foramen.The value for patients under 3 years must be 0 and in older children this ranges from 0 to 22%. We can measure the lateral displacement of the femoral head with regard to the Perkin line by dividing the width of the head that crosses the Perkin line by the diameter of the head. This leads to four quadrants and a normal femoral head has to be located in the inferomedial quadrant.

(B) Perkin line is perpendicular to Hilgenreiner line, touching the lateral margin of the acetabular roof.

This line is used to measure the acetabular angle and as a reference for Perkin line.

(A) Hilgenreiner line, connects the inferior tips of the iliac bones, at the triradiate cartilage.

The most useful lines and angles that can be drawn in the pediatric pelvis assessing hip dysplasia are as follows: The range of normal values is from 90 to 135° and is related to the infant’s age. Lines are drawn from the highest point of the ischium to the most prominent point of the symphysis, joining at the inside of the pelvis.

Symphysis os-ischium angle (of Tönnis): This evaluates the pelvic position in the sagittal plane.

In neutral rotation the ratio is 1 but is considered to be acceptable when it is between 0.56 and 1.8.

Obturator foramen diameter ratio (of Tönnis): A quotient of pelvic rotation by dividing the horizontal diameter of the obturator foramen of the right side and that of the left.

Reliability of measurements increases if indicators of pelvic alignment are taken into account: Unfortunately the time the joint gives a good x-ray image is also the point at which nonsurgical treatment methods cease to give good results.Ĭhildren Image quality checking Image quality checking. When the infant is around 3 months old a clear roentgenographic image can be achieved. Ultrasound imaging yields better results defining the anatomy until the cartilage is ossified. By statistical methods, normal and pathological joints can be separated as follows: in adult Hip Values, between 6 and 15 indicate a normal joint form values between 16 and 21 indicate a slight deformation and values of 22 and above are indications of a severe deformation, in children in the normal range the Hip Value reaches 14 values of 15 and up are pathological.X-rays of hip dysplasia are one of the two main methods of medical imaging to diagnose hip dysplasia, the other one being medical ultrasonography. A new measurement-the Hip Value is based on measurements of the Idelberg- Frank angle, the Wiberg angle and MZ-distance of decentralization.

It is more important to look for the relationship between femoral head and acetabulum. Investigations of the shaft-neck angle and the degree of anteversion including the wide standard deviation demonstrate that it is very difficult to determine where these angles become pathologic. Above the double standard deviation only severe dysplasias were present. X-ray measurements of the hip joints of children, with special reference to the acetabular index, suggest that the upper standard deviation of normal comprises the borderline to a critical zone where extreme values of normal and pathologic hips were found together.

Normal pediatric hip xray