Developmental Dysplasia of the Hip – Imaging
Perkins (Vertical) and Hilgenreiner’s (Horizontal) Line
Teardrop is not ossified and is WIDE (does not have the femoral head to push against it and stimulate development
Tonnis grades of dislocation: a located hip lies in inferomedial quadrant of Perkins/Hilgenreiners
– 25-35 in the newborn
– should decrease to no more than 25 in the 25 month old
– should follow it to make sure that it continues to go in the right direction
– better than x-ray for the first 3 months
– Graf technique – reliable at about 2-4 weeks of age (enough ossification to make it valid)
– alpha angle represents slope of the acetabulum – the shallower the acetabulum, the smaller this angle becomes – therefore want lots of alpha! (normal > 60)
– beta angle represents slope of cartilaginous labrum – as the hip dislocates, the labrum gets pushed up and away from vertical, increasing the angle – hence, you want less beta (normal
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