But new technology and therapy have made it possible for some people to take major steps.
When Matt Courson shattered his back bone in a truck accident last year his doctors said he would never walk again. But, since working with specialists at the Center for Spinal Cord Injury in Baltimore, he has regained sensation and movement in his legs.
The therapy includes water therapy and a computer that sends electrical impulses to a patient's legs, causing them to contract, and relax while riding a bicycle.
Although Matt has a long way to go before he can walk without assistance, his doctors and family believe that he will eventually do it.