used when walking is difficult or impossible due to illness, injury, old age-related problems, or disability. These can include spinal cord injuries (paraplegia, Hemiplegia, and quadriplegia), broken leg(s), cerebral palsy, brain injury, Osteogenesis imperfecta a.k.a. brittle bones, motor neuron diseases (MND), multiple sclerosis (MS), muscular dystrophy (MD), Spina bifida, and more.