How do hand prostheses work

High-tech instead of immobile prosthesis: the myoelectric arm prosthesis

The high-tech arm reaches for an object at a speed of 300 millimeters per second and thus corresponds to the highest standard of medical technology.

Thanks to its skin-like silicone cladding, the prosthesis not only looks very similar to the natural arm, but also enables the user to grasp, hold and be active.

"What is special about the myoelectric arm prosthesis is that the prosthesis wearer can decide for themselves whether they want to move quickly, slowly, vigorously or gently," explains Petra Rudnick from the TK medical center is hidden in the stem of the prosthesis. "

How exactly does the myoelectric arm prosthesis work?

Patients control the myoelectric prosthesis with the muscles of the remaining arm stump. Muscle signals are generated by tensing and relaxing the flexor and extensor muscles in the forearm. A microprocessor in the shaft of the prosthesis measures the myoelectric impulses via skin electrodes and uses them to calculate an electrical control signal for the actuators (= motors) of the prosthesis that move the arm and hand.

Technically always better

The hand and arm prostheses are continuously being developed today. Powerful, lightweight batteries and new control options in the electronics enable good fine motor skills and a natural appearance of the prostheses.

"In the past few years, the technology of myoelectric prostheses has developed rapidly," says Rudnick. "This means that we can now better respond to the needs of people who have lost an extremity."

But that is far from the end of the research and development of prostheses. Future visions of a prosthesis contain an integrated minicomputer that makes movement even more intuitive and natural. The computers should be able to predict the movement intentions of the prosthesis wearer at an early stage.

Intensive training is a must

Adults and children who wear a myoelectric arm or hand prosthesis require intensive prosthesis training because the high-tech arm is not so easy to control. Training the muscle signals is as complex as learning to play a musical instrument.

Occupational therapists support those affected in relearning movement sequences such as eating with a knife and fork. Children train their new robotic arm in a playful way.