Biomedical Engineering Reference
In-Depth Information
knee cannot adapt to changes in the terrain or changes in gait if the user were to carry a
backpack, for example. More recently, systems have been developed that can adapt the
knee state to changes in the environment. The Rheo-Knee from Ossur was developed as
a result of research conducted by Herr a few years ago (Herr and Wilkenveld, 2003).
10.9.5.2 Knee Prosthetics
The two main concerns in prosthetic leg design are a healthy, natural walk and safety.
Amputees actually fall quite often because they cannot feel their foot and do not know
what the knee joint is doing because effective proprioception is limited. In the past, safety
concerns were not compatible with a natural movement, which is fundamental to diminish
the negative effects of uneven posture and the resulting back pain. However, this has
changed with the introduction of intelligent passive prostheses in the 1970s and active
knee and leg prosthetics only a decade later. Examples of these intelligent knee prostheses
are shown in Figure 10-56.
An example of an intelligent passive prosthesis is the C-Leg
®
by Otto Bock. First
introduced in 1997, it struck a balance between these two needs. It has had numerous
revisions, and new models have been created, with the most recent being the C-Leg
compact, shown in Figure 10-57.
Strain gauges in the tube adaptor and a knee-angle sensor are used to determine
the ankle moment above the foot adapter as well as the angle and angular velocity of
FIGURE 10-56
Examples of knee
prostheses.
(a) Intelligent passive
prostheses.
(b) Active knee
prosthetic. (Courtesy
of Endolite, Otto
Bock, and Össur,
with permission.)
FIGURE 10-57
The C-Leg range by
Otto Bock is a
state-of-the-art
actively controlled
knee prosthesis.
(a) Fitted to a
human patient.
(b) Prosthesis
hardware. (Courtesy
of Otto Bock, with
permission.)
