here is some info on it
Aseptic Femoral Head Necrosis
a friend of mine had a leg perthes dog she was helping with for a rescue who had the surgery - if you want you can contact them on this site to talk to them about it and let them know debbie referred you and hopefully they can shed some light on this
Legg Perthes
she had starlette i believe
Legg Perthes