Paraplegia describes any form of paralysis that renders both legs immobile or lacking in sensation. It's almost always caused by an injury to the spinal cord or a congenital condition in the thorcic, lumbar, or sacral regions.
Some people with paraplegia can walk, but in most cases are wheelchair dependant. Impotence and incontinence are also associated.
Some of the complications that can arise in patients with paraplegia are pressure sores, thrombosis, and pneumonia.