All you need to know about Smart prosthesis
A smart prosthesis is a prosthesis that combines prosthesis function and artificial intelligence. We will first explain what prosthesis is and then define what artificial intelligence is to be able to lead to the term "intelligent prosthesis."
To treat deficient organs, doctors have several methods. Among other things, one of these methods consists in using artificial substitutions for functions or organs such as prostheses, in replacing an organ that has disappeared and prostheses to assist a segment that has lost its motorization capacities. The technical problems are different if they are supplements placed outside the body or if they are implanted artificial organs. These two categories have made enormous progress, due to the introduction of new materials, advances in electronics, computers, and above all, a better understanding of how the human body works.
The term artificial intelligence designates the development of automatic procedures that aim to seek solutions for all types of problems. These procedures are expressed in the form of programs executable by computers. There are different kinds of problems, like learning chess games or solving theorems. But since the 1970s, new fields have appeared, such as image analysis, medical diagnosis, recognition of forms and speech, understanding of language.
The history of the prosthesis begins with the archaeological discovery of a mummy toe made of leather and wood dating from the 15th century BC.
In 1858, a leg of copper and wood, probably dating back to the 4th century BC, was discovered in Capri, Italy. It is the oldest vestige of the prosthetic leg.
In the middle Ages, they were often very simple assemblies of wood, metal, and leather, the whole constituting a crutch barely improving.
The hand of Ambroise Paré in the 16th century, therefore, did not make him the forerunner of the artificial prosthesis. The rebirth is despite everything a period of progress due to Leonardo da Vinci or Jacques Besson.
Nowadays, prostheses have evolved in particular due to the appearance of duralumin (an alloy of copper and aluminum), which has allowed considerable reduction. Subsequently, new materials appeared, such as kayak resin, acrylic resin, or the thermoplastic technique (softened and draped plastic sheets).
The forces brought into play in the gait analysis.
Spatio-temporal analysis of walking
The Spatio-temporal analysis is characterized by the length of the stride, the duration of the walking cycle, and the duration of the support sequence.
- Kinematic analysis of walking
Kinematic analysis is the study of the effect of forces, such as displacement, speed, and acceleration. In the first step, the foot is positioned flat on the ground; it is called the support phase. The individual exerts a force that is equal to its mass and which is supported by the socket shown schematically in this carbon fiber modeling. The stump is suspended due to a hydraulic system. The knee is blocked to allow the individual to keep his balance. The bending angle is 17 °.
Secondly, the left leg is forward, and the right leg gradually begins to bend; the march begins. The amputated leg exerts a swinging movement. The elevation of the heel is characterized when the ankle of the prosthetic foot tilts through a latch mechanism, under pressure. Therefore the knee is relatively stretched; we notice that the flexion angle is close to 0 °.
The third stage is called the pendulum phase, which is caused by sending the stump forward as if the individual had a valid leg. The prosthesis is in suspension, which means that it is no longer in contact with the ground. When the valid leg reaches the ground, the prosthetic knee performs a pendulum movement, which gradually slows down due to hydraulic brakes; this mechanism then becomes automatic and makes it possible to stabilize the individual. The bending angle is 65 °.
In the last step, the prosthesis gradually renews contact with the ground. Thus, the prosthesis returns to the initial support phase, and walking becomes fluid.
- Dynamic gait analysis
Dynamics is the study of the forces acting on a material system, here the prosthesis. The mechanical principles used are Newton's laws which are as follows:
- Newton's first law or the principle of inertia: If an object is at rest or its motion is uniform rectilinear, then the sum of the external forces exerted on it is zero, and vice versa:
- Newton's second law or the center of inertia theorem: The vector sum of the forces applied to a point object is equal to the product of the mass of the object by its acceleration vector:
- Newton's third law or the principle of reciprocal actions: If an object A exerts a force on an object B, then this object B exerts a force on A of the same direction, of the same intensity, but of the opposite direction.
We use the system of a force platform to record the forces transmitted by the human body to the plateau. These forces are constituted by the weight and the actions of contact between soil and plantar surface.
The Power Knee
- What is it?
The Ossur Power Knee is the only motorized prosthesis in the world for transfemoral amputees.
This highly intelligent prosthesis thus offers potentials which have hitherto been absent.
-It replaces muscle activity.
-It provides the power necessary to maintain walking speeds.
-It allows its user to descend slopes and stairs, due to an elevating movement.
- Provided with numerous sensors, it collects information and thus has the capacity to anticipate.
-It continuously adapts to the specific approach for an efficient and natural movement.
- How it works
The Power Knee allows the user to perform more complex activities.
Its aluminum frame has an external design that reflects the anatomical shape of the leg just below the knee.
A few sensors, as well as a combination of accelerometers and gyroscopes applying artificial intelligence, control the movement and power of the knee. They also accurately measure the forces and the load applied to the knee in all circumstances.
This data is transmitted to the transported computer, in which artificial intelligence successfully predicts the next movement that it wishes to make.
She also assesses the symmetry of the gait to help reduce tension on the back, hips, and healthy leg. The battery is removable; it can, therefore, be replaced by another fully charged and easily accessible to the user.
A mechanism guarantees active lifting for climbing stairs, resistance to steep terrain, and smooth forward propulsion for walking on level ground.
The active principle of the knee, therefore, restores the symmetry, balance, and power of the amputee's gait.
The individuals have to climb stairs every day, and the Power Knee is perfectly suited, but walking is what they enjoy most, and sometimes they do it without stopping for two and a half hours. They can now walk with their family and friends without being the one they always have to wait for. The Power Knee will undoubtedly assist amputees in realizing their potential.
Technical means used
The materials used
We distinguish in the prosthesis two parts, The socket, and the prosthesis.
- The socket engages two techniques which are as follows:
- The molding of the plaster stump which begins with the creation of a shell, then a molding adapted to the patient, then development for pleasant maintenance. When the mold is empty, we call it a negative mold, and when it is full, positive mold.
- The digital acquisition makes it possible to make a scan of the stump. The disadvantage of plaster is that it is dirtier and can only be used once, while the scanning method is clean and reusable. It should be taken into account that the socket must be adapted to the skin.
- The prosthesis is most often made of carbon composite, especially for athletes, because it saves time and dynamism. We also use acrylic resin as well as the thermoplastic technique.
In our case, we note that high-tech prostheses allow greater walking comfort, as well as a larger walking perimeter. High-tech prostheses are heavier, because batteries have to be transported, and they make noise.
Some contain microprocessors, gyroscope which make it possible to give the position in space, accelerometer.
After the creation of the socket and the prosthesis, we carry out the verification; we control the alignment and comfort.
Then the patient practices rehabilitation to learn to walk.
The goal is to put the prosthesis on like a shoe. As a rule, the prosthesis lasts three years. During a morphological change (weight gain), we only change the socket and not the foot.
General and economic problems
- In general, replacing a deficient or missing organ with an artificial system requires knowing the specifications of the replaced structure. We had to decrypt the programs and try to understand the functioning of Man with an analysis of walking. In bipedal mode, which is a specification of human locomotion, two functions come into play. The propulsion uses thrusts on the ground and stabilization, which calls upon numerous sensors to allow balance.
- The technologies to be used to create reliable artificial organs are of a high level of research, explaining the need for significant investments. For manufacturers, the complexity of the technical problems linked to biocompatibility, resistance over time, and reliability of permanent research require high budgets, which therefore increase the price of prostheses. This economic problem is actually a real societal choice. For a country, the health economy does not necessarily lead to the health of the economies.
The price depends on whether the prosthesis is approved by the state or not. Some prostheses are covered by social security except sports prostheses and smart prostheses not approved by ISMP.
Example: The C-leg, an approved intelligent knee or even Harmony, an intelligent ankle also approved. The Power knee, an unapproved knee, costs around 60 million euros.
- Mayer's right
Mayer developed tables of the lunar cycles and evaluated the errors created by the measuring instruments. He used for the first time, like Euler, an adjustment method to study the position of a point on the Moon.
His method is one of the methods which allow obtaining an affine adjustment of a double statistical series. A statistical adjustment is when the point cloud of the double series (X, Y) is roughly aligned, we seek a relationship between X and Y of the form y = ax + b, which approximates Y as a function of X.
This Mayer's linear adjustment method, or method of discontinuous averages or moving averages, consists of sharing a cloud of kxn points arranged in the order of their abscissas, by k points, n consecutive points being replaced by their average. This type of adjustment corrects imperfections between close measurements.
- Use of GeoGebra software to calculate, using data from 1993; 1997; 2001; 2003, an estimate of the number of people who will wear a prosthesis in 2025.
We have seen that smart prostheses are only able to partially replace natural limbs or organs. Likewise, the human body is complex, and today's technologies do not have the same effectiveness in the functions of daily human life.
Nevertheless, smart prostheses have undergone a remarkable technological advance. They allow, for example, regaining the feeling of touch and to succeed in walking almost normally, which was unexpected a few years ago. The amputees were therefore condemned to move in a wheelchair, on crutches, or even equipped with a passive prosthesis (function only aesthetic).
We, therefore, consider that this type of prosthesis makes part of the autonomy of its user despite the transport of a battery and the lack of strength felt by the individual. So, indeed, smart prostheses are part of a person's life plan. However, each individual has their own life plan, and depending on the budget they can devote to it, the use of this type of prosthesis will depend on it.
Author: Vicki Lezama