Maltron makes ergonomic keyboards, and has been accommodating people who only have use of one hand for a while. The company also offers its Ergonomic 3D Keyboard, an expensive proposition that claims to fit the shape of the hands and accommodate the different lengths of fingers, reducing movement and tension.
There's no wrist twisting involved, and the tilted keys make it so you don't need to move your hands very far to get the job done. The number keys are centrally located for either hand to use.
The only downside of this keyboard is that you must be a touch typist to enjoy its benefits, and then, well, there's that hefty $490 price.