To add AMA Styles to Word:

Download this this file and extract it to your computer.

Place the File in the following location:

For Windows 32 bit and Office 2007
C:\Program Files\Microsoft Office\Office12\Bibliography\Style

For windows 32 bit and Office 2010
C:\Program Files\Microsoft Office\Office14\Bibliography\Style

For Windows 64 bit and Office 2010
C:\Program Files (x86)\Microsoft Office\Office14\Bibliography\Style