Current prosthetics on the market have come a long way in looking natural, but in the grand scheme of things, they're quite primitive: the best offer mechanical operation, but they're missing a decidedly human touch: feeling.
That neurological aspect is vital to a full understanding of the world we live in. Two new studies are investigating how to bring feeling -- neural stimulation -- to prosthetic limbs.
Physicians at the American Society of Plastic Surgeons "Plastic Surgery 2009" conference this week in Seattle announced the discovery of a polymer that conducts electricity like a wire and promotes the stimulation and growth of nerve fibers. The molecule -- 3, 4-ethylenedioxythiophene, or "PEDOT" -- is a promising first step in connecting to severed nerves and providing amputees with more neurological control of their prosthetics.
That translates to the ability to move fingers independently, apply an appropriate amount of pressure to objects (for example, to grab and lift a delicate item) and feel sensation.
In one study, plastic surgeons say they may have found a way to successfully grow new nerve fibers after they've been severed in an injury. The PEDOT polymer, along with other biologic and synthetic materials, was grafted onto the severed leg nerve of a rat. New nerve fibers grew and took over function from the severed nerve, reawakening muscles that were unable to be stimulated due to nerve injury.
In another study, plastic surgeons designed a cup containing cells and muscle that fits around the severed leg nerve of a rat. The PEDOT polymer was wrapped around the cells and muscle in the cup to provide electrical charge. After 114 days, the study found that new muscle and blood vessels had formed, nerve fibers had sprouted and muscle fibers began compensating for lost nerves. Doctors confirmed that sensation had returned.
The presentation was authored by Y. Jadchela, M. G. Urbanchek, M.R. Abidian, B. M. Egeland, W. M. Kuzon, D. R. Kipke and P. S. Cederna. The research is funded with a $5.5 million U.S. Department of Defense grant.