BACKGROUND: Earlier this year, the FDA approved the NESS L300 to help provide a more natural gait and improved mobility for people with neurological disorders, such as stroke patients, those with traumatic brain injury, multiple sclerosis, or incomplete spinal cord injury. When an individual walks, he or she alternately swings his or her legs forward. During this phase of gait, the L300 electrically stimulates the muscles in a paralyzed leg to lift the foot. It is a form of functional electrical stimulation (FES). The manufacturer, Bioness, is testing its latest product at two sites in the US.
HOW WE WALK: Walking is different from a running gait because only one foot at a time lifts off the ground. During forward motion, the leg that leaves the ground swings forward from the hip, like a pendulum. Then the leg strikes the ground with the heel and rolls through the toe in a motion similar to an inverted pendulum. The motion of the two legs is coordinated so that one foot or the other is always in contact with the ground -- a so-called 'double pendulum' strategy. The process of walking recovers about 60% of the energy expended thanks to the pendulum dynamics and the ground reaction force. (The legs act as long levers that transfer ground reaction force to the spine.)
ABOUT STROKES: A stroke occurs when a blood clot blocks an artery (a blood vessel that carries blood from the heart to the body) or a blood vessel breaks, interrupting blood flow to an area of the brain. When either of these things happen, brain cells begin to die and brain damage occurs. When brain cells die during a stroke, abilities controlled by that area of the brain are lost. These abilities can include speech, movement and memory. How a stroke patient is affected depends on where the stroke occurs in the brain and how much the brain is damaged. For example, someone who has a small stroke may experience only minor problems such as weakness of an arm or leg. People who have larger strokes may be paralyzed on one side or lose their ability to speak. Some people recover completely from strokes, but more than two-thirds of survivors will have some type of disability. Stroke is the third leading cause of death in America and the leading cause of adult disability.