You want something that will be warm by blocking wind and maintaining body temperature, yet it's also important that the coat has closures that you can easily manage by zipper, buttons, velcro, even magnets sewn into portions, or another method that accommodates your functional ability. If self-securing the closure is not an option, you can simplify by getting a parka or leave the coat zipped, buttoned, or strapped and pull over your head, similar to putting on a shirt.