Griner arrived at the medical centre last Friday after she US officials secured her freedom from a Russia in an exchange for Russian arms dealer Viktor Bout.
Griner, a star of the Women's National Basketball Association's Phoenix Mercury, was arrested on February 17 at an airport outside Moscow for carrying vape cartridges containing hashish oil in her luggage.
She was subsequently convicted of drug smuggling and was been transferred to one of Russia’s most notorious penal colonies, where former inmates have described torture, harsh beatings and slave labour conditions.