How Do Prosthetic Arms Work?

Maybe you’ve just started to consider a prosthetic arm for yourself, or maybe you’re helping a loved one through the process of getting fitted for a prosthesis. Whether you’re just starting your journey or you’ve been considering a prosthetic arm for quite some time, understanding how a prosthetic arm works might shed light on the topic.



Location of the Amputation: Is a Joint Involved?

Just as understanding the mechanics behind a prosthetic leg, the first step in understanding a prosthetic arm is determining the location of the amputation. The location of the amputation determines how many joints are involved. Where is the amputation located?

  • Below the elbow: Amputations below the elbow are referred to as either transradial or BE for short. The resulting prosthesis is called a prosthetic forearm.
  • Above the elbow: Amputations that occur above the elbow are known as transhumeral or AE for short. This prosthesis involves both the prosthetic lower arm as well as the prosthetic upper arm. Because this amputation involved a major joint, the prosthesis will also include a prosthetic elbow.


Components of a Prosthetic Arm

Curious about the parts of a prosthetic arm? The basic elements include the prosthetic limb, the socket, the terminal device or hand, the suspension system, and the control system.

  • The limb: Just like with prosthetic legs, the limbs of a prosthetic arm are formed out of durable (yet lightweight) materials.
  • The socket: The socket “connects” the prosthesis to the patient’s limb (also known as the residual limb). In other words, the socket is the piece that comes into contact with the limb so that there is secure fit. Because an ill-fitting socket can cause discomfort, the team at Advantage Prosthetics and Orthotics creates a personalized mold to create the prosthesis – ensuring that the fit is unique to you.
  • Suspension system: The suspension system ensures that the socket and limb remain secured to the residual limb. Examples of suspension systems include an elastic sleeve, harness, self-suspending socket, or suction socket.
  • The control system: While a limb is controlled by nerve-impulses and brain control, a prosthetic arm cannot be controlled in the same manner. Control systems can be body-powered or myoelectric. In a body-powered prosthetic, the hand is operated through cables and a harness – which are then operated by the opposite shoulder. Myoelectric prosthetics work through the use of electrodes.


Single prosthetic arm over blue background.


What Happens After I Receive My Prosthetic Arm?

The road from amputation to successfully living with a prosthesis involves two key events: occupational therapy and several adjustments. Occupational therapy will help you learn how to use your new arm and perform everyday functions with it. This is particularly helpful if you opted for a myoelectric arm. Likewise, the adjustments will ensure that you have a proper fit; without a proper fit, you might find it more difficult to use your arm.