News

Limber Limbs

The Straits Times (26 July 2012)

Better artificial limb technology now allows users to swim, play basketball and even wear high heels.

Losing one leg or both no longer means you have to stop doing the sports you enjoy.

With better technology, artificial or prosthetic legs now allow an amputee to return to running, hiking or other sports he likes, said Mr Trevor Binedell, the unit head of the prosthetics and orthotics department at the Foot Care and Limb Design Centre at Tan Tock Seng Hospital.

This is provided the patient's wound has healed well and he is physically healthy, he said.

Some amputees have the mistaken idea that if they lose their leg, they cannot return to their previous lives.

'But the thing that limits them more often is their mentality rather than the technology,' said Mr Binedell.

Manufacturers now offer lighter, more durable prosthetic parts fabricated from materials that are better able to mimic human walking.

There are now prosthetic legs to cater for different activities - running, hiking, golfing, cycling and swimming.

At The Foot Care and Limb Design Centre, prosthetists will custom-make a leg by first creating a mould of the patient's stump and designing a socket which will fit it snugly.

They then order prosthetic components, such as the knee unit, foot and adaptors, from overseas companies.

The centre is the largest of its kind here, and has its own workshop to custom-make prosthetics. Most of its patients are diabetics who require lower-leg amputations.

Depending on the needs of each patient, there is a wide variety of artificial legs and feet to choose from.

A below-knee prosthesis, which includes the socket, foot and pylon (internal frame), costs from $1,300 for a basic leg to $8,000 for a high-activity leg. These are subsidised rates.

An above-knee prosthesis, which also includes the knee system, ranges from $3,700 for a basic leg to about $14,000 for a high-activity mechanical leg. These are subsidised rates too.

The costs of more advanced prostheses, such as the C-leg and the bionic leg, can go up to more than $50,000.

Those newly fitted with a prosthesis will usually need to return to the centre within a year to change the socket, as the stump tends to become smaller as the muscles waste away, said Mr Binedell.

The other prosthetic parts can usually last three years.

It is important to keep the stump clean and dry to prevent bacterial infection, which are 'not uncommon', said Mr Binedell.

He shares some of the different features of prosthetic legs and feet available on the market.


TYPES OF LEGS

MECHANICAL LEG (right)

This usually contains a number of axes (or bar systems) which allows the knee to bend like a normal knee. The more axes the leg has, the more it can mimic natural knee movement and the more energy efficient it is. Mechanical legs are suitable for those who wish to cycle and run. Prostheses for these activities usually come with seven axes.

COMPUTER OR C-LEG

This offers certain advantages over conventional mechanical knee prostheses. It comes with a microprocessor with multiple sensors which can detect the movements of the leg and allow amputees to speed up and slow down. The sensors also allow users to walk down stairs continuously step after step, rather than taking one step and stopping before taking another step.

The C-leg is also safer because of its sensors. For instance, it can help amputees recover from stumbles without the knee buckling. It is good for patients who are afraid of falling. However, it is deemed too sensitive for activities such as running.

BIONIC LEG (right)

This uses artificial intelligence and has almost the same capabilities as the C-leg. However, it is less restrictive and may be preferred by younger and more athletic amputees.

The C-leg sometimes exerts too much control when a person is walking. For instance, when the user wants the knee to swing faster, the C-leg will not allow it.

The bionic leg is more for patients who are not afraid of falling. It is also not recommended for activities such as running.


TYPES OF FEET

MULTI-AXIS FOOT (right)

This can move up and down, as well as side to side. Hence, it conforms better to uneven surfaces and can better absorb some of the stresses of walking on the stump compared to the single-axis foot.

Suitable for amputees who want to vary their walking speed.

SINGLE-AXIS FOOT

This contains an ankle joint that allows the foot to move up and down, enhancing knee stability. The full sole or front part of the foot can come into contact with the ground more quickly than a less flexible foot, thereby making it more stable.

It may, therefore, be more suitable for an amputee with an above-knee amputation who needs more stability. It is suitable for everyday walking at a constant pace.

DYNAMIC RESPONSE OR ENERGY STORING FOOT (right)

This can store and return some of the energy generated during walking and running. It has a spring mechanism in the base which gives the wearer a subjective sense of push-off, a more normal range of motion and style of walking.

It makes walking and running more energy-efficient and less tiring. Suitable for amputees who wish to walk at different speeds and do more strenuous activities such as running, play tennis or badminton, or hiking. Some have no 'feet' and come with just a blade at the base.

ADJUSTABLE HEEL (right)

This comes with a knob that can be manipulated such that the heel can be moved 2.5 inches up. This comes in useful for women who want to wear high heels.

In another version, suitable for swimmers, the knob can be manipulated so that the foot is in plantar flexion (toes away from shin position).


OTHER FEATURES

SHOCK ABSORBER (right)

It is usually made of carbon with a spring inside, or it can be a high-density rubber ball. It is good for amputees who wish to do activities which may be stressful on the knee, such as hiking and golfing, as well as sports which require a lot of jumping, such as basketball and volleyball.


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Source: The Straits Times © Singapore Press Holdings Limited. Reproduced with permission.