What types of arms are there?
There are 3 general categories of arms.
The first is referred to as cosmetic or passive. This type of hand does not open or close and so has no active gripping capabilities. This lack of mechanics results in a lighter weight.
A prosthetic hand may also be custom made, usually of silicone, to create a virtually exact match.
The second type of prosthetic arm is called conventional or cable operated. This prosthesis has either a hook or a hand that opens and closes to allow gripping and manipulation of objects. It is also possible to choose from a wide variety of terminal devices (TD), depending on a chosen activity
The TD is operated by the pulling of a cable that is attached to a harnessing system. The harness goes across the back with a loop through the opposite armpit.
The conventional arm is very capable of assisting with most activities. It is very straight forward, simple to operate and durable.
The third type of prosthetic arm is called myoelectric. This is the most complex of the upper extremity devices.
The myoelectric arm is operated through flexion from the remaining muscles in the arm. Within the prosthetic socket, there are sensing electrodes that pick up the underlying muscle activity.
The training involved in using one of these types is more extensive. The extra effort though is well worth it, recent developments in myoelectrics have produced such things as hands with sensors in the fingertips that automatically readjust grip force to prevent dropping something being held.