Prosthetics 101: Choosing the Right Device by Type and Function

There are over 2 million people living with limb loss in the United States, 30-50% of which use a prosthesis to carry out their daily lives. This rate is typically higher among below-knee amputees, as below-knee prosthetic devices tend to offer greater functionality and are generally easier to use than their above-knee counterparts. By definition, a prosthetic device is as an artificial device designed to replace a missing body part and restore aspects of functionality/ appearance. With ongoing advancements in technology and design, the range of prosthetic devices available to amputees has expanded significantly. These devices are categorized in multiple ways - by level of amputation, functionality, and intended use. This blog explores the basic prosthetic types, provide examples of each category, and demonstrates how these classifications can assist patients on the imperative journey of choosing the right prosthetic device for their lifestyle.

Prosthesis: Definition, Types & Living With Prosthetics (clevelandclinic.org)

Classification by Level of Amputation

The first classification focuses on the level of amputation.

1. Transradial prosthetics are devices for patients with amputations below the elbow, typically replacing the forearm and hand. Modern examples of transradial prosthetic devices include sophisticated myoelectric prosthetic hands with multiple programmable grip patterns and customizable settings. These devices allow users to perform a wide range of activities, from holding small objects to handling larger items, using advanced electronics and motors to mimic the movement of a natural hand.

2. Transhumeral prosthetics are designed for patients with amputations above the elbow and share similarities with their transradial counterparts. These devices often feature modular designs with various control options, including sensors that respond to muscle signals. Modern transhumeral solutions boast prosthetic arms that provide precise grip, elbow movement, and flexibility, allowing users to execute complex hand movements, including wrist rotation.

3. Transfemoral prosthetics are designed for patients with amputations above the knee. Today’s innovative transfemoral prosthetics utilize microprocessor-controlled knees that adapt in real time to the user's gait and movement, facilitating smooth, natural movements across diverse terrains, including slopes and stairs. These devices support natural walking patterns with multiple programmable modes and enhanced stability features.

4. Lastly, Transtibial prosthetics are devices for patients with amputations below the knee. There is a wide range of prosthetic device options for transtibial amputees, ranging from microprocessor-controlled foot-ankle systems to customized 3D-printed devices that offer energy return and flexion that reduce impact on the residual limb.

Categorizing prosthetic devices by level of amputation is essential for tailoring prosthetic solutions to the unique functional needs and anatomical requirements of different users.

Classification by Functionality Type

Prosthetics can also be categorized by functionality type, leading to four primary classifications: passive prosthetics, body-powered prosthetics, externally powered (myoelectric) prosthetics, and hybrid prosthetic devices.

1. Passive Prosthetics: These are non-moving devices primarily designed for cosmetic purposes and basic functionality. For example, a cosmetic hand can provide stability but lacks mobility and grip strength. Often made of silicone, these devices mimic skin tone and texture, offering visual symmetry without full functionality.

   
   

2. Body-Powered Prosthetics: These devices rely on the user’s body movements to control the prosthetic’s functions. While less common for lower limbs, there are traditional mechanical devices, like mechanical knee joints controlled by the user’s body mechanics or energy-storing feet that release stored energy during movement, providing momentum without any powered components.

   
   

3. Externally Powered (Myoelectric) Prosthetics: This third type of device uses electrical signals from the user’s muscles to power motors, allowing intuitive movement. When a user contracts certain muscles in their residual limb, electrodes in the prosthetic device detect these small electrical signals and translate them into movement in the prosthetic. This process allows users to operate their prosthetic hand, arm, or leg intuitively, using muscle signals to perform actions like gripping, flexing, or lifting, as they would with a natural limb. For instance, transradial myoelectric prosthetics offer advanced control with various grip patterns, enhancing the user’s ability to perform everyday tasks.

   
   

It is important to remember that there is no "one-size-fits-all" solution when selecting a prosthesis. Understanding your activity levels, required daily tasks, and physical limitations as an amputee are instrumental in determining what type of prosthetic device to invest in.

Limber Provides a Custom Transtibial Prosthetic Solution

Limber's groundbreaking product, the UniLeg, is the world’s first fully 3D-printed transtibial prosthesis that is 30% lighter than traditional legs, water-resistant, and fully functional. Our digital fabrication process and advanced technology create completely customized devices that are tailored to the needs of each below-knee amputee for an improved socket fit, comfort, and durability, allowing our patients to walk, fish, train, and swim with confidence.

Additionally, the UniLeg has passed extensive testing to exceed the AOPA Foot Project standards and provide ample energy return for our users. As modern technology continues to evolve, so too will the options of prosthetics available, and Limber remains dedicated to this mission of enhancing mobility and quality of life for amputees. To learn more about the UniLeg, visit our website.