By "Type"

  1. Identified in perinatal period and respond well
  2. Secondary to neuromuscular disorder
  3. Teratologic disorders

By "Degree"

  1. Hip instability
  2. Hip subluxable
  3. Hip dislocatable
  4. Hip dislocated

Radiological

  1. Epiphysis medial to Perkins & below Helgenrieners
  2. Below Helgenrieners but lateral to Perkins
  3. Lateral to Perkins at level of acetabular margin
  4. Lateral to Perkins and above acetabulum

Also "Early" or "Late"