For rehabilitation clinics
The .REHAB domain extension fit perfectly with any rehabilitation center website name in a lot of ways. For one it will provide the center a chance to pick a very catchy website name that will be easy to remember and memorize also. Plus the chances that your cool name is taken on a popular generic name such a .COM/.ORG is taken is pretty high. The .REHAB domain extension gives you the chance to use your intending names.
For rehabilitation blogs and forums
Being surrounded by a group of people with a common interest of getting better will sometimes help to improve one level of commitment to getting better also. So if you take about rehabilitation on your blog or you own a forum where people going through same problem can openly discuss and heal, then you need to buy a .REHAB domain name for such a website now to improve your traffic and narrow down your target audience also.
For personal rehabilitation journal blog
Do you want to document every moment of your rehabilitation process online for private or public consumption? Then buying a .REHAB domain ending for such endeavor seems like the right thing to do