Technology in Prosthetic Legs

Advances in prosthetic technology are changing the way society perceives those who find themselves in the possession of fewer limbs than usual. With access to the right technologies, individuals who used to be perceived as "disabled" are now on an even ground, if not in the possession of "super-abilities". This is particularly noticeable in the case of lower limbs. For instance, South African athlete Oscar Pistorius can outrun and outlast "able bodied" athletes on the track although his lower legs were amputated when he was one year old, and para-athlete and model Aimee Mullins can confidently stride on the catwalk on prosthetic legs designed by fashionista Alexander McQueen.

Blade Running

• A prosthesis does not necessarily have to be a simulacrum of the real thing. Leg prostheses designed for high speed running like those used by Oscar Pistorius are not inspired by human legs, but by those of the Cheetah. Even then, the resemblance is hard to see. Athletic Cheetah legs are often described as blades, carbon fiber springs bent in the shape of a sickle. The design maximizes the energy return of the limb so when the feet hit the ground the energy gets pushed back towards the sprinter, propelling him forwards. However, the design of the leg does not allow for stationary balance and the user must run or fall, making athletic legs unsuitable for daily life.

Bionic Legs

• The apparently simple act of walking requires countless minor adjustments in the muscles of the knees and ankles in order to adapt to changes in the terrain or in the speed of the gait. Traditional prostheses cannot make those adjustments by themselves, requiring additional effort and concentration on the side of the user or leading to unnatural-looking gaits. Many modern prostheses have bionic technology, however, where microprocessors allow the electric knees and ankles to respond to changes in the slope of the terrain, to the presence of stairs, or simply to the extra impulse required when the user stands from a chair.

Beautiful Legs

• Because prostheses are often seen as medical devices, their design tends to prioritize function, comfort and cost. For the users however, prosthetics can become part of their bodily self-perception, making aesthetic considerations important. For example, para-athlete, model and activist Aimee Mullins wears carbon-fiber legs covered with a polyurethane foam sculpted both to her specific requests and the aesthetic imagination of the prosthetist, giving a life-like appearance down to the capillaries, veins, moles and even tattoos. Unlike the average leg prosthesis, that is basically designed to work with orthopedic shoes, hers has feet positioned for wearing high heels.

Myoelectric

• An ideal prosthetic limb would be controlled by the will of the wearer, just like a real one. Myoelectric legs take a step in this direction by detecting the natural electricity given up by the muscles of the stump and using it to trigger the electromechanical components of the prosthesis. The use of this technology is more widespread in prostheses for upper limbs, where fine control is paramount. However, some prosthetic legs use this functionality too, as their use can help in achieving a more natural gait, and allows for a faster adaptation by new users.

Drawbacks

• The main drawback of prostheses using advanced technology is in their high cost, as what is considered medically necessary for American insurance standards is often whatever can get the user from the bed to the toilet. This places legs like those of Aimee Mullins (whose construction takes a technician two weeks to sculpt) or those of Pistorius (made of expensive carbon fiber) out of the reach of the average user.

  For users interested in competition against "able bodied" athletes, sports legislation can be problematic, as prostheses are sometimes classified as an "unfair advantage". Also, prosthesis users need to schedule extra time when traveling by plane, as their limbs are often subject to multiple security scans.