Biomedical Engineering Reference
In-Depth Information
10.8.4 Foot Prosthetics
Prosthetic feet must be capable of ankle rollover, must function as shock absorbers, and
must return as much energy to the system as possible at the start of the swing phase. As
shown in Figure 10-18 their design has evolved considerably since the introduction of the
first Flex-Foot
®
in 1984.
As a result of changing attitudes among amputees, some of these prostheses are
designed to be worn uncovered because they are both beautiful and extremely efficient.
The two people shown in Figure 10-19 who have done much to promote this attitude are
athlete, model, and activist Aimee Mullins and Oscar Pistorius, who was banned from the
Beijing games because of a supposed unfair advantage over able-bodied athletes.
Should the amputee choose to cover the prosthesis, Dorset Orthopaedic and other
companies can provide handcrafted silicone cosmeses based either on an existing limb or
on a suitable alternative. These “skins” can be extremely lifelike, as shown in Figure 10-20,
but alternatively can be patterned to suit the mood of the user.
As with the knee, there is a strong demand for prosthetic feet that are affordable by
the world's poor. This is a particular problem in regions such as Angola, Vietnam, and
Iraq, among others, where millions of antipersonnel mines still take their toll.
According to a survey conducted at the S.M.S Medical College in Jaipur, India,
most existing passive foot prostheses are designed for First-World environments and are
unsuitable for barefoot use. As a result of the survey, the following guidelines were drafted:
•
The foot should be wearable with or without a shoe; it should therefore look like
a foot.
FIGURE 10-18
Evolution of Össur
artificial feet for
different
applications.
(Courtesy of Össur,
with permission.)
