Approach to DDH – Acetabular Dysplasia
– after treating the dislocation, you must follow the kid to see if the acetabulum is developing normally.
Look to see what the pathology is:
– is it dysplasia of the acetabulum with a shallow cup – acetabular index down, sharp angle down?
– is it a coxa valga with superior loading?
– is it both?
– is the dysplasia causing recurrent instability? Then you better get on with an osteotomy
– if reduced, it is somewhat controversial to decide when to do the osteotomy – wait for remodeling, or just go ahead and do it to encourage better remodeling? Probably a more aggressive approach is warranted – if the acetabulum is not developing normally after a couple visits to the clinic, pull the trigger.
– cannot have degenerative arthritis
– should have a good range of motion (how good is debatable)
– should check an abduction/internal rotation x-ray to assess two things: congruency and coverage. On this view the head and acetabulum should be CONGRUENT to proceed with a re-directional osteotomy (Salter, Triple, Steel). If reduced but not completely congruent, consider acetabuloplasty – Dega, Pemberton (more in the CMT or paralytic population). If not reducible – need a salvage procedure (Chiari or Shelf).
– look at the femoral neck shaft angle – is the deformity there? Does it need a varus osteotomy? Most have lots of anteversion and not that much valgus, so a varus osteotomy runs the risk of elevating their GT and causing an abductor limp. If doing a varus osteotomy, remember to medialize the femur with the offset on the plate.