Prosthetic Limbs: Future Technology
Two main up and coming technologies in the field are bionics and direct bone attachment.
Bionic Limbs
Bionics is the field of artificially reproducing the work of natural biological systems. Touch Bionics in Scotland have managed to develop ‘the worlds first fully articulating and commercially available bionic hand’, known as the i-LIMB Hand. This technology is based on the same myoelectrical signals mentioned in the previous section, with the difference that all five fingers are independently powered. Also the way the robotic hand’s fingers are screwed on allows the patient to replace any damaged finger with just a trip to the clinic rather then, as with traditional devices, go for weeks without the prosthetic limb.
Direct Nerve Connection
At the Human Assisted Neural Devices (HAND) program at DARPA (the US Department of Defence science office), scientists are looking into controlling all the fingers through direct nerve connection with the residual limb.
Osseointegration
Direct bone attachment allows a prosthesis to be attached to the body without the use of a socket, which often is the cause a problems with amputees. It is based on the principle of osseointegration (used also for prosthetic replacement of teeth).
Osseointegration involves the implanting of manufactured, load bearing mechanisms directly into the bone, with the additional property of the fixture bonding with the surrounding body tissue. The load bearing device is normally made of titanium, and is inserted into the bone, which after some time grows around it, making it firm, completely attached and tight. The prosthetic limb is then attached to the device, which is protruding out of the femur (tight bone). Although with this technology the amputee has more muscle control and can use it for a longer period of time (compared with normal stumps and socket), it cannot be used for rigorous activities such as running because of the increased impact this has on the bone, which may cause it to break.
Other Innovations
Researchers are also looking into a variant of the TSR mentioned previously, but for the foot. Pressure sensors in the feet connect to electrodes in the stump from which then the nerves can get the signals.
Another development is an inbuilt computer in the upper prosthetic leg which matches the amputee’s pace and so makes walking easier and more natural.