I am 27 years old and bound to a power chair due to severe back pain and spinal disease. I have had multiple surgeries and will soon have more. I would like to be active but I know that is nearly impossible due to me being bound to a power chair and the inability to walk except for around the house without a cane. Is there a way or a special bicycle that is made that I can ride a bike??? Please help! I'm dying to get out more without my chair!
I would think some sort of a tricycle would be the best choice for you, probably a recumbent.
Something like this is the first thing that comes to mind:
You lay in a reclined position and pedal with your feet in front of you. These come in several variants, from fully reclined (such as the above) to more upright.
There are also numerous variations of the hand-powered cycle, and some that are operated with both hands and feet such as this one:
Some of these are "stock", while others are fairly highly customized "one-off" bikes. (But several versions of the basic tricycle recumbent are available "off the shelf" at relatively reasonable prices.)
I never seen any of these bike styles with an auxiliary motor, but I'm sure there are some. Several battery-assist systems are available for standard bikes and could be easily adapted to a recumbent. A full-power gasoline engine would be a bit more complicated.
There is always the hand crank option. I've ridden with a guy who was riding one of these and he was flying.
There's a few different kinds of bikes you could try. A charity called Wheels for Wellbeing in London has a list of some of them on their website, including trikes, recumbents, and handcycles (as suggested by other people here), the Veloplus (a bit like a trike that you can use to also carry a wheelchair(!)), and side-by-side tandems if you'd like to ride with somebody else.
I have no personal knowledge but have heard of the Courage Center. It is an organization that helps people with varied challenges with rehab and fitness issues. A German company called Stricker makes a bicycle type attachment that connect to a standard wheel chair, unfortunately their website doesn't translate all of it into english.