While some robotic arms use signals transmitted from a microchip which has been implanted into the brain, myoelectric arms use a signal (EMG) which is generated by a muscle when it is either flexed or is contracted.
This signal travels from the muscle through an electrode which is attached to the skin. It is first amplified, processed through a controller and then activates a switch in the motor which controls the function of the prosthesis.
The Limitations of a Myoelectric Prosthesis
Most artificial arms are controlled by the remaining muscles and nerve endings in the area adjacent to the amputation. Although this technique is certainly effective in providing patients with a functional prosthesis, there seems to be a consensus among the amputees as to the prosthetic’s limitations.
First, because the prosthesis requires the amputee to consciously control each movement of the device, such as elbow and wrist movement, there is a lengthy training period involved. Secondly, patients find the devices to be slow, limited to performing one movement at a time. In order to overcome these limitations, a new technique was developed which provided the amputee with a prosthesis that better mimicked a natural limb.
Expectations of our clients have changed. Not only the younger amputee, but also the active geriatric expects to be able to ride a bicycle, play golf, tennis, or job around the block. Our challenge is to meet these expectations.
We know that the comfort of our prosthesis is paramount to your lifestyle – if you would like to talk to us about your artificial limb call (775) 849-0958
AMyoelectric Prosthesis New Approach to the Myoelectric Prosthesis
Understanding the limitations faced by amputees, scientists took a very different approach. Their goal was to develop a prosthetic which would be:
- Fully Functional Shortly After Attachment
- Able to Operate Much Faster
- Capable of Performing Multiple Functions Simultaneously
- More Natural
In order to achieve their goal, it was necessary for scientists to take an entirely different approach. Instead of attaching the prosthesis to the muscles and nerve endings which are located in the area of the arm near the amputation, they developed a surgical technique which allowed them to transplant the shoulder’s sensory nerves into the patient’s chest muscles.
Once these nerves became integrated into the chest muscles, they began to function in the same manner as they did in the shoulder prior to the amputation. When the patient anticipates moving their wrist, a message is sent to the nerves now located in the chest, sensors send the signal to the proper motor located in the prosthesis, and the function is performed without conscious effort on the part of the amputee.
Myoelectric Prosthesis – Looking Ahead
Although myoelectric robotic arms have been able to resolve many issues experienced by amputees, scientists are considering some additional needs which need to be addressed. Instead of transplanting only the nerve endings which transmit information regarding limb movement, techniques are being developed which will include sensory nerves in the process.
Even though the current generation of myoelectric robotic arms will provide the amputee with a prosthesis which closely mimics a natural arm in the area of functionality, there is one very important factor missing. When the arm is used to grasp an object, the sense of touch is missing. By implanting the nerve endings which allow the user to “feel” the object the prosthetic is touching, the myoelectric prosthesis will in every way feel as though it were a natural arm.
Myoelectric prosthesis fabrication is a new emerging technology for amputees.