Prosthetics out on a limb

28 October 2014

A prosthesis is an artificial device which replicates a part of the body. It is designed either to be functional, cosmetic or both. This could be a leg, tooth, eye, breast, hip etc.

Whether a part of the body has been lost to trauma, disease or due to a congenital condition, a prosthesis can now be developed and manufactured to meet the specific need of the individual.

The world of prosthetics is developing rapidly in line with technological advances. Nowadays prostheses are not just designed for practical mechanical requirements but for comfort, capabilities and aesthetics. A younger candidate may require a highly advanced leg for athletic purposes. We certainly witnessed many Paralympians wearing the latest designs who were fiercely competitive and successful in London 2012!

Oscar Pistorius, famously known, apart from his most recent conviction for the shooting of his girlfriend Reeva Steenkamp, as the "Blade Runner". He was briefly ruled ineligible to compete in the 2008 Summer Olympics because his transtibial prosthetic limbs were said to give him an advantage over runners who had ankles! It was suggested that he used 25% less energy than those of an able bodied man running at the same speed. In 2012 Pistorius became the first amputee to compete against able bodied athletes at the Olympic Games and made history winning the 400 metres with his carbon fibre prosthetic legs called "Cheetahs" shaped to curve like the fastest animal on land.

Lower limb prostheses can now be specifically designed for the user to engage in almost any sport for example horse-riding, sailing, skiing, cycling and snowboarding.

German manufacturers launched two major products in 2012 for above knee amputees. These were prosthetic knees which have a microprocessor controlled device allowing the user to negotiate almost any terrain with ease and to step up and over objects. A second knee designed was specifically for water based use e.g. showering and swimming.

Comfort is however key to the fitting of a lower limb prosthesis as with the old type of limbs often the user could not tolerate wearing the prosthetic limb due to the poor fit of the socket which interfaces between the residual limb or stump and the prosthesis. A good socket design is therefore key to successful function.

Unfortunately upper limb technology is not advancing as rapidly as with lower limbs possibly due to the fact that there is less demand. Lower extremity patients outnumber upper extremity patients by 30:1. Fitting upper limb prostheses is complicated and challenging. The best outcomes are for the replacement limb to act as a tool for doing things rather than as a replacement limb. A human hand is so complex to mimic but recently a five year old girl who was born without fully formed fingers to her left hand was the first child to have a prosthetic hand made with 3-D printing technology.

Ocular prosthetics are common. However they cannot yet provide vision. Maybe this will be possible one day but a glass eye these days are very life-like and are made from high quality cross-linked acrylic. The artificial eyes are connected to muscles which allow them to move in unison with the good remaining eye.

Whatever the type of prosthesis is needed it is important to choose a good Prosthetist for the design and fit but proper rehabilitative support will be required in addition particularly for upper and lower limb prostheses. The person literally has to learn how to walk again or to move an arm which is wired up completely differently than before.

As time passes there will be regular maintenance and replacement required so the cost can escalate. Unfortunately the funding under the NHS is not always available for a bespoke service with the latest advances so unless there is access to compensation as a result of a personal injury or clinical negligence it might be difficult to raise the funds required.