What does "basket case" mean?

A person or thing too impaired to function. For example, The stress of moving twice in one year left her a basket case, or The republics of the former Soviet Union are economic basket cases. Originating in World War I for a soldier who had lost all four limbs in combat and consequently had to be carried in a litter (“basket”), this term was then transferred to an emotionally or mentally unstable person and later to anything that failed to function. [Slang; second half of 1900s]