taken the biggest efforts in its development, has been the knee prosthesis. The knee
performs an stellar role during the whole gait cycle, and this is basically due to the fact
that the knee joint sets the difference between a rigid leg, with one body from the hip
until the ankle, and a leg made of two bodies, articulated between each other through it.
This is the case in human body between thigh and shank, being this leg configuration
from which it is understood a natural gait. Moreover, this last feature, leaving aside
damping and impulse functions of feet, is what makes human gait the most efficient
mode of moving human body from one place to another.
Considering the previous ideas, the authors has aimed this paper to identify
research lines developed by scientific community, with respect to the knee joint, and
particularly, external prostheses for replacing the natural one. Three scientific research
lines have been identified, considering them as scientific research lines that have
become necessary over the years, searching to develop a prosthesis that allows to
reproduce a natural gait, and thus, to solve the A/K amputee problem at least regarding
mobile performance.
In next paragraphs, these research lines are described, but first of all it is worthy to
mention, that also in sockets and ankle-foot prostheses, important developments have
been done. In particular, the socket is of special relevance, since it is the link between
the remaining limb and the rest of the prosthesis. If socket does not guarantee enough
comfort and security at interface with the prosthesis, the patient is not going to use this
prosthesis regardless of the other components of it. In this sense, studies have used
finite-element method as a tool for developing these components (Lee and Zhang, 2005;
Lee et al., 2004), and in particular, softwares to design them are available today (Otto
Bock, 2007a, b). Regarding ankle-foot prostheses, there is a variety of these
components, made by different manufacturers that use innovative materials developed
from elastomeric compounds and carbon fiber (Prosthetic Feet – Otto Bock, 2007;
Prosthetic Feet and Shock Absorbers – Ossur, 2007). These components are passives,
and besides the expectation of a not-so-far development of an artificial
muscle-based-technology to turn these into active prostheses (Bar-Cohen, 2004;
Herr and Kornbluh, 2004), there was nothing real active in this field up to now.
Recently, a MIT team presented an ankle-foot prosthesis, with multiple tendon-like
springs and an electric motor that make it a real active prosthesis (MIT News Office,
2007). This prosthesis promises to be an active ankle-foot prosthesis that imitates more
accurately damping and impulse natural behaviour of a sound foot, reducing fatigue,
and hence providing amputees with a more efficient gait.Prostheses design
Normally, it is the prosthesis what is seen, no matter scientific research that support it,
but actually every product at the market is intimate and unavoidably related to
scientific research carried out until the moment of its launching. It is enough to see, on
one hand the evolution of knee prostheses offered at the market, and on the other one
the scientific evolution in the development of these, to be aware of it.
The first designs that introduce notable features, compared to the peg leg used initially
to substitute the natural knee, were the constant-friction and the friction-brake designs.
Prostheses as the 3R22w and the 3R15w commercialized by Otto Bock house, are result of
scientific research that took place in Europe after the end ofWorldWar I (Na ¨der and Na ¨der,
1993; Radcliffe, 1977). These knees, although evolved compared to what was available
before the war, presented serious problems to the possibility ofwalking at different speeds, 膝关节假肢英文文献和中文翻译(3):http://www.youerw.com/fanyi/lunwen_7366.html