Can arimidex (anastrozole) be used to help stop the bone plates to fuse to early?

Experimental. Only studied in pubertal boys for short periods of time. Side effects may include: very elevated testosterone levels, vertebral bone deformities and infertility. As no long term safety studies exist, and the outcome for stature improvement is controversial between some studies with small number of subjects, using aromatase inhibitors is considered experimental by the pediatric endocrine society.
Yes. Arimidex (anastrozole) (generic called anastrazole) is an aromatase inhibitor. It works by inhibiting the conversion of testosterone to estrogen via the aromatase enzyme, hence the name. Such inhibition means that there will be less estrogen exposure at the growth plates allowing delayed closure (a process that is estrogen dependent) . Talk with your endocrinology specialist, esp that its use remain off label.