Developmental Dysplasia of the Hip – Osteotomies
After doing the closed or open reduction, it is possible that you will be left with some acetabular dysplasia. Some of this dysplasia might get worked out for you by the body’s remodeling potential. But sometimes you need to give it a hand.
What’s abnormal? shallow acetabulum, anteverted acetabulum, and anteverted femur.
– the older the child is when the reduction happens, the more severe these abnormalities are, and the less potential remodeling the child has left.
– in general, remodeling of the hip may continue to improve the hip joint until about the age of 8; which is to say, that after the age of 8, the results of osteotomies are less successful (but they are still done).
– if the reduction of the hip is not concentric, or if AVN occurs, the dysplasia will not remodel
If the hip demonstrates progressive subluxation (ie. the anatomy is such that it is not sufficient to keep the head located) or if it remains unstable during an open reduction because of acetabular insufficiency or femoral anteversion, then an osteotomy is obviously indicated at that time (or shortly thereafter) to get the hip STABLE.
But what do you do in the young kid if the hip is concentrically reduced but shows persistent acetabular dysplasia?
– Salter: proposed osteotomy for kids after 18 months
– Lindstrom: proposed that you should let the acetabulum remodel as much as possible, which it does until the age of 8; then after that decide what the deficiency is, and do the necessary osteotomy.
In general, it is probably sensible to do the osteotomy if you observe the hip
for two years and there is no improvement in the acetabular angle.
What about in the older child or adolescent?
– little controversy here – any significant degree of dysplasia in a patient over 8 is an indication for surgical intervention if coverage can be achieved.
– start with finding out if the hip is or can be concentrically reduced – abduction/internal rotation view (30 abduction, 15 internal rotation)
If not reducible – then you’re stuck. They need a shelf or Chiari salvage osteotomy – and for this you might as well wait until they’re pretty symptomatic
If reducible – then you’ve got some options.
– Ask yourself – Does the acetabulum need to be re-directed, or does it need to be reshaped? Or is it the femur that needs to be osteotomized. Where is the pathology – that is where you start. And remember, if there is pathology on both sides, and you’re not quite sure, you can always do the acetabulum first and see what happens.
If the acetabulum just needs to be re-directed:
Salter: not a terribly powerful osteotomy; you can gauge how much coverage you’ll gain by looking at how much coverage there is on the 30/15 AIR view.
Steel: triple osteotomy – much more powerful
Sutherland: double osteotomy – more powerful, but prominence of the piece in the groin makes it less popular
If it needs to be re-shaped:
Pemberton – acetabuloplasty; closes down the anterolateral aspect of the acetabulum by hinging it on the open tri-radiate cartilage. Make sure the tri-radiate cartilage is actually intact!
Dega – acetabuloplasty, closes down the posterolateral aspect of the acetabulum, again by hinging it on the open triradiate cartilage. Useful in the paralytic dislocation.