Hi Md. Daher,
Thank you for your query.
It is not possible to suggest whether your son requires one surgery or two without examining him and seeing his X-rays. The nature and extent of deformity
will decide the surgery. Hence it is not possible to work out the cost too.
I suggest you exchange all the relevant clinical documents with the orthopedic surgeon who will then decide the surgeries to be preformed, when and where to be performed.
I hope I have answered your query to your satisfaction.
Wishing your son all the best.