An official website of the United States government
The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before
sharing sensitive information, make sure you’re on a federal
government site.
The site is secure.
The https:// ensures that you are connecting to the
official website and that any information you provide is encrypted
and transmitted securely.
Ullrich PM.Ullrich PM.Phys Med Rehabil Clin N Am. 2007 May;18(2):217-33, vi. doi: 10.1016/j.pmr.2007.03.001.Phys Med Rehabil Clin N Am. 2007.PMID: 17543770Review.