You have possibly just found out that your child has something called Perthes Disease, or to use the full name, Legg-Calve-Perthes Disease. First let me re-assure you that this is not in the usual sense, a 'disease' - it is not contagious, or any of those other things that are generally associated with that word. It should be referred to as a 'condition' - one that will affect not only the child with Perthes, but the entire family.
There may be changes in lifestyle that will need to be made, as well as decisions about treatments and therapies. There will possibly be some grieving involved, as the dreams you had for your child will likely need to be modified, to allow for any restrictions imposed. But remember through all of this - this is a life-altering condition, not life-threatening!!
Statistics generally say that the birth rate for Perthes is 1:1,200 (833 per million). There will be 4 boys diagnosed with perthes for every girl. Bilateral Perthes is generally only 8-10% (67-83 per million) of that.
I have no medical training whatsoever, just the knowledge that comes from having had Perthes as a child and also having two children with it.
An orthopaedic specialist is the best person to tell you what you should, or shouldn't do to ensure the best possible outcome for your child. However, I am hoping that you find information here that can help, with what its like on a day-to-day basis, dealing with the restrictions imposed on the child; different treatment options; allowances and help that may be available. Also the longterm effects of a 'Perthes hip' and what that will mean through their teens and into adulthood.
If you are a teen or adult, you may wonder what the future holds. Am I likely to need a hip replacement? If my hip starts hurting, where do I go for help? For a woman - will I be able to get pregnant, carry a baby to term, more likely to need a caesarian section?