What might be some causes of needing a wheelchair other than being a paraplegic?

Many: Muscular dystrophy, cerebral palsy, polio, brain injury, cardiac failure, als, amputation, brain tumors, multiple sclerosis, and the list goes on. Of course many more people 'use' a wheelchair, than 'need' a chair, for safer mobility, community access and comfort after surgery. My personal joy as a rehab doc is seeing our communities more accessible for all who roll.