You won't find entire MD/PhD programs that are geared towards this topic per say, but you can find schools with strong rehab programs and strong engineering programs and cross the two yourself. Rehab isn't my area of interest, though I am told northwestern has an excellent program for rehab engineering (and clearly an excellent medical school). You could also look at schools with strong neural engineering programs that do work in prosthetics and neural robotics such as Duke and Pitt. If you know the field well, I would encourage starting with schools with notable rehab/eng research. Current and past PIs would be able to recommend programs. If your list seems slim, expand it by thinking of ways you could bridge strong unrelated engineering programs to clinical rehab work. Most MD/PhD programs will tend to be heavily weighted towards basic biomedical research, even those in BME. If you are really looking to dig into the engineering/device side of this field, I've found that schools that have strong classical engineering programs (mechE, EE, chemE) often foster the positive engineering environment that most MD/PhD programs don't.