This is a natural progress of Perthes disease. There is no medication except pain-killers off and on. The only way you can retard the progress of the disease, the secondary osteoarthritis, is by bringing whatever life-style change you can bring to reduce loading on this joint. Your doctor can advise you in detail about this. At some stage you will have to opt for surgical options. I say, patient should ask for surgery in these cases, which means that he should think that his life-style is severely affected by disability.