Expert opinions, TECHNOLOGY

Bionic prosthetic legs: Modern technology expands horizons

Ever since the Ancient Egypt civilization to this day, scientists and engineers have been trying to create lower limb prostheses that are as similar to the lost limb as possible, both in appearance and in function. For a long time, all amputees could count on was the limited functionality of mechanical modules replacing the lost joints of the limb. Modern medicine and science, and development of bionic technology in prosthetics is about to greatly facilitate the lives of such patients.

Bionics (βίον is an ancient Greek word for “living”) is an applied science that uses biological methods and systems found in nature in the design of engineering systems (such as prostheses). Bionic prostheses can significantly improve the quality of rehabilitation for people with disabilities. Their functionality is to the maximum extent similar to the biomechanical principles of motion of a natural lower limb and is capable of improving the patient’s walking experience in a wider variety of situations.

A modern bionic prosthesis is based on microchip technology. The main control system of a bionic module that replaces a lost appendicular joint has receptors connected to external environment. At an extremely high frequency (up to 1,000 times per second), sensors collect data on the nature and incline of the bearing surface, load on the prosthetic limb, speed and gait cycle phases. 

Thanks to the receptors, the central microchip receives and processes all the information required for the artificial module to work. The smart prostheses allow users to control the module in real time with modern devices and move at their own comfortable pace. Sockets connecting residual limbs with modern bionic prostheses are usually made of high-impact lightweight materials. The entire electronic system is powered by a compact built-in lithium battery that lasts up to one week. 

However, bionics is still in the early stages of its development. The first bionic module of a knee joint was developed by Ottobock, a well-known German prosthetics company, and presented at the world orthopedics conference in Nuremberg in 1997. 

In 2006, Icelandic company Ossur and Massachusetts Institute of Technology developed a microprocessor-controlled knee Rheo Knee, and later the Proprio Foot, a bionic microprocessor ankle that permitted swing-phase dorsiflexion on stairs. The next step of the bionic prosthetics development was the integration of the electronic knee module and electronic ankle in one neural system: the result was named Symbionic Leg. In 2015, German concern Ottobock manufactured the first water-proof bionic knee, which allows the user to dive at the depth of up to three meters and engage in all other kinds of water activities.

It is important to bear in mind that the prosthetic socket is the most important part of any prosthesis. If the user cannot put it on, if it is uncomfortable or hurting, they will not be able to use even the most advanced prostheses. Marlo Anatomical Socket is currently the most advanced technology. orthotic and prosthetic center is currently Russia’s only manufacturer of such sockets.

As of today, the most advanced developments available at the Russian consumer market are the following bionic systems:

1. C-Leg, 4th generation, the most common bionic module produced by the German company Ottobock and used by millions of people worldwide. The prosthetic device allows patients to fully rehabilitate themselves in the environment and even engage in sports activities.

2. Rheo Knee XC, the most advanced microprocessor-controlled prosthetic knee developed by the Ossur company. The adaptive microprocessor system constantly monitors the user’s movements and can predict them.

3. Proprio Foot, one of the world’s first AI controlled ankle-foot prostheses developed by Ossur. The module can independently perform automatic ankle flexion and extension movements when walking up and down stairs, and functions nearly as a healthy human limb.

4. The Genium prosthetic knee, manufactured by Ottobock, recreates a natural physiological gait pattern. The module utilizes a rare function that allows for variable stride length during stair walking. The walk-to-run function allows for instantly switching between a regular walking pattern and rapid stride or running. In addition, the Genium prosthetic knee is fully waterproof.

5. Symbionic Leg, a fully bionic prosthetic leg developed by Ossur. The device allows the most complex patients with short above-knee stumps and bilateral amputations to socialize and return to active lifestyle. The device recreates a physiological gait pattern and allows for walking up and down stairs and engaging in sports activities.

By Maxim Gusev, head of the department of lower limb prostheses and foot pathologies, orthotic and prosthetic center. 

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