Page 247 - Handbook of Biomechatronics

Lower-Limb Prosthetics 243

device that will compensate for the missing functionality, and together with
the remaining limb, will act as a totality close to the natural leg. Out of all
these daily activities, walking is the most important one since it is a prereq-
uisite for the rest of the activities; that is, walking is a basic prerequisite for
healthy living. Even after surgery, patients need to walk in order to maintain
their vascular system without blood clots, which can cause deep vein throm-
bosis, heart attacks, or strokes. To provide amputees with quality lower-limb
prostheses, the functional characteristics of the natural leg during walking
must be identified first, that is, a good understanding of the human gait is
needed to allow for the development of a good model for it, and have it
incorporated these into the prosthesis’ design. We believe that some of
the functional characteristics of walking are the shape of the foot, the shock
absorption of the leg, and the “straight leg” nature of walking. Without under-
standing these functional characteristics, and without incorporating them
into a model of walking, the lower-limb prosthetics will be limited in use-
fulness and will not achieve the performance and adoption they can.

2.1.1 Adjust to Terrain and Task?
One of the features that would be desirable is that the prosthesis recognizes
the terrain conditions and the task that the amputee wants to perform and
adjust accordingly (Hansen and Starker, 2017; Major et al., 2018). For exam-
ple, if the amputee is walking with a walking prosthesis and suddenly he/she
wants to run, the prosthesis should recognize his/her intention automati-
cally, and adapt to perform this task accordingly. The same would be desir-
able for all other tasks, for example, dancing, running, ascending and
descending stairs, hopping, etc.

2.1.2 Enable Nonambulatory Amputees (e.g., Bilateral Transfemoral
Amputees)
The most challenging population of lower-limb amputees is the bilateral
transfemoral amputees. The more proximal the amputation the more diffi-
cult it is for an amputee to walk due to the fact that current above the knee
prostheses presents significant drawbacks such as limited controllability, and
requires significant amount of energy. Duplicate the above drawbacks and
add that there are balance problems for the bilateral transfemoral amputee
and then it becomes clear why a high percentage of this population is in
a wheelchair and not mobile. It would be a measure of success, if prostheses
of the future would find ways to enable these amputees to ambulate.