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. The AP of the whole pelvis (not shown on the X-rays on this page) should be fully assessed because pelvic fractures can mimic the clinical features of a hip fracture.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. Standard viewsĪP (Anterior-Posterior) pelvis and Lateral hip. Particular care is needed in assessing the X-ray when physical examination is limited, for example if a patient is acutely confused. Repeat X-rays, CT or MRI may be required if pain persists. In this case the X-ray may not show an obvious fracture. It is important to be aware that the common clinical signs of a shortened and externally rotated leg may be absent if the fracture is not displaced. Many hip fractures are clinically and radiologically obvious. Remember to assess the surrounding pelvic bonesįractures of the proximal femur or 'hip' are a common clinical occurrence in elderly, osteoporotic patients.
Particular caution is required in the case of acutely confused patients.Not all hip fractures are visible on the initial X-ray and follow-up imaging may be required if concern remains.