A myoelectric prosthesis is an electrically controlled prosthesis that uses electrodes mounted within the socket to receive electrical signals from the muscle contraction. These signals are sent to a motor in the prosthetic elbow and/or wrist. A myoelectric elbow may then bend or straighten, a wrist can flex, and a hand can open or close. There are many different types of myoelectric prostheses and there are various manufacturers that produce these devices.
The functional envelope refers to where the prosthesis must be placed, in reference to the user’s body. A myoelectric prosthesis allows for a very wide functional envelope, including above the head and below the waist. Depending on the user and prosthetic design, the prosthesis may also be operated behind the back.
Myoelectric prostheses typically do not involve elaborate harnesses or cables and rely on very subtle muscle movements. This frees the user to be able to perform more complicated fine motor skills while still operating the prosthesis. The user also has control of grip strength and speed.
If the prosthetic user has experienced severe trauma or damage/atrophy to necessary muscles or joints, the functional envelope may be temporarily or permanently limited regardless of the use of a myoelectric prosthesis. Limited range of motion in the shoulder and/or elbow can often be improved with the introduction of physical and occupational therapy. Regular exercise and stretching of the residual limb can maintain a wider functional envelope for all prosthetic users.
The ability to have control over the prosthesis in a wide functional envelope can be crucial for certain activities and for certain occupations. Every effort should be made to maintain the widest functional envelope possible.