| Initial stage | increased head-socket distance, subchondral plate thinning, dense epiphysis |
| Fragmentation stage | subchondral fracture, inhomogeneous dense epiphysis which is porous, metaphyseal cysts |
| Reparative stage | normal bone in areas of resorption, removal of sclerotic bone. epiphysis is more homogeneous |
| Growth stage | re-ossification. normal femoral shape is approached |
| Definitive stage | final shape determined with joint congruency or incongruency |