This guide introduces common categories of leg and arm amputations and prosthetics. Learn about the different types of prostheses, as well as what to expect when being fitted with a new prosthesis.
Prosthesis vs. Prosthetic
Many people wonder how to use the terms “prosthesis” and “prosthetic” properly. A prosthesis is the substitute limb worn by the amputee, and and the plural of prosthesis is prostheses. Prosthetics refers to the field and science of creating prostheses.
Leg Amputation and Prosthetics
Leg amputations are performed either above or below the knee. Modern prostheses are customized to match the wearer’s lifestyle and grant them a full range of movement.
Types of Prosthetic Legs
A wood or urethane foam prosthesis with a hard plastic shell. This prosthesis is heavier and less customizable than an endoskeletal prosthetic. But it is more durable and long-lasting.
A prosthesis with an inner support pylon made of light-weight materials such as aluminum or titanium. Feet and knees can be swapped out. This makes the endoskeletal prosthesis easily adjustable for different activities and active lifestyles.
For above-the-knee amputees, there are a variety of prosthetic knee joints available at different price points and with different functionality. There are two basic types:
• Single-axis knees: hinge-style knees that can only bend forward and backward.
• Polycentric knees: also referred to as “fourbar” knees, they can rotate on multiple axes.
There are plenty of considerations when choosing a knee joint, including the level of rehabilitation and the various stability and motion control options available at different price points. For more detail on the many options available, read our post on prosthetic knee systems.
Fitting a Prosthetic Leg
The affected leg must be given time to heal before wearing a prosthesis. Most patients begin rehab with a temporary prosthesis within the first three months. A test prosthesis is specialized to help with physical therapy and gait training. It is customizable for adjustments as the patient progresses.
A plaster cast of the residual limb or a 3D laser scanner creates a custom prosthetic socket. The initial test socket is flexible to adjust to the reduction of swelling in the residual limb. It serves to minimize pressure and abrasion.
During rehab, your feedback on the fit provides the specialist with the information required to cast a final socket. They help you choose a prosthesis for your leg based on your lifestyle and activities.
Arm Amputation and Prosthetics
Arm amputations are either above or below the elbow. Arm prostheses that allow wearers to manipulate and grip objects to live independent lives. Electric prostheses can even move based on signals from the wearer’s muscles.
Below The Elbow (Transradial) Amputation
Below the elbow amputations are performed between the hand and elbow. Prostheses are designed to replace the forearm, wrist, and hand.
Above The Elbow (Transhumeral) Amputation
Above the elbow amputations are performed at or above the elbow. As most of the arm is removed, a hybrid prosthesis is the best option to provide the motion of the elbow and also provide grip.
Types of Prosthetic Arms:
A three-harness cable system prosthesis that allows the wearer to grasp objects, flex and lock the elbow. This is the least expensive type of arm prosthesis. There are two varieties of body-powered prostheses that offer different hand functions:
• Voluntary Open: opens the hand when applying tension to the cable
• Voluntary Close: closes the hand when applying tension to the cable
An electrically powered prosthesis that resembles a real arm. The user controls it with electrical impulses through muscles in the residual limb. This option is more expensive than a body-powered prosthesis and it needs frequent recharging. It also requires a great deal of fine-tuning to get the prosthesis to interpret the electrical signals, and may not work for all people.
Most electric prosthetic arms provide basic grip functionality. But some of the latest electric prostheses have fully controllable fingers.
A combination of both body-powered and electrical components. This type of prosthesis is generally used for above the elbow amputations. It’s specialized to enable a greater range of motion and function for the wearer.
Fitting a Prosthetic Arm:
Fitting for a prosthesis will wait until the arm has fully healed. The residual limb is cast from either plaster or a 3D laser-model to create a test prosthetic socket.
The test socket is clear to allow for specialists to observe the skin during rehab. This allows them to see where the skin is coming into contact with the socket during movement. A specialist uses these observations to create a definitive socket. Then, they discuss what type of prosthetic arm is right for you and your lifestyle.
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