Glossary: Components of a Prosthetic Leg

You may find it helpful to learn about the different parts of your prosthetic leg, which may include any or all of the following components:

Prosthesis

A prosthesis (plural: prostheses) is an artificial device that replaces a body part lost through trauma, disease or a congenital condition. The components of a prosthesis depend on the body part it replaces. If the prosthesis replaces a leg, for example, you can call it a prosthetic leg.

Socket

The socket connects your residual limb to the prosthesis and is the foundation of the device. A proper fit is essential to ensure that you can function comfortably and effectively. Since no two residual limbs are the same, the socket is custom-designed and manufactured to suit the shape of your residual limb and to accommodate for individual nerve and skin patterns.

Liner

The liner plays a key role in suspending the socket from the residual limb. It also serves as a protective barrier between your skin and the socket. Because the socket and suspension are fundamental to the effective functioning of a prosthetic leg, it is impossible to overstate the importance of selecting the right liner.

There are three main ways to attach a liner to your socket:

  • a locking pin at the end furthest from the residual limb (locking liner)
  • an extra sleeve applied over the liner and socket (cushion liner)
  • a vacuum with a seal (seal-in liner)

Lately, the effectiveness of seal-in liners, which essentially operate through a passive vacuum system, has been demonstrated with the addition of a pump that sucks air out of the socket, creating an even stronger attachment.

Prosthetic Knee

A prosthetic knee mimics the function of a biological knee by providing safety, symmetry and smooth movement when walking. It also provides stability when standing and a range of motion that makes sitting and kneeling possible. The knee is one of the most complicated joints in the human body, so designing a prosthesis that functions like a biological knee can be challenging. If the design forces the user to walk in an unnatural way, they may experience back and hip pain or if the knee doesn’t suit the user’s physical requirements, it may cause them to fall. Be sure to communicate with your prosthetist to ensure you are getting the comfort and functionality from your prosthetic knee to meet your mobility needs.

Prosthetic Foot

A prosthetic foot should imitate the function of a biological foot by providing a safe platform, handling differences in terrain and allowing the individual to walk in a natural, symmetrical way. The foot is the main prosthetic component responsible for absorbing the shock generated by impact on the ground.

Adapters

An adapter is any prosthetic component that links the main components, such as the liner, knee and foot together. Adapters can vary from components such as a simple tube (which is called a pylon) to an expulsion valve in a vacuum system.

Cosmesis

A cosmesis is a lifelike covering made from a material such as silicone or PVC. Its purpose is to mimic the appearance of a biological limb and may be complete with freckles, veins, hair or even tattoos. A cosmesis can also protect the prosthetic components from the elements.

Some types of cosmeses are ready-made, but for a truly realistic appearance a cosmesis must be custom designed and manufactured by a prosthetist who specialises in this aspect of prosthetics. The use of a cosmesis is a personal choice. You will get to weigh the benefits of appearance of a cosmesis against the extra costs and potential impacts on functionality when deciding whether to wear one or not.

Specialised Components

Prosthetic technology has come a long way toward helping amputees enjoy greater mobility and a life without limitations. Some of the most advanced prosthetics, like Bionic prosthetics, have on-board microprocessor computers and artificial intelligence (AI) that automatically adjust to changes in terrain and adapts real-time to your walking speed and style.

While the same prosthesis can be used for a range of activities, such as hiking, jogging and showering, other activities, such as sprinting, long-distance running and swimming, require a specialised prosthesis. If you plan to go sprinting regularly, it’s better to use components made specifically for that, such as the Cheetah blade.

One recent innovation from Össur is a unique crossover foot prosthesis inspired by the original Cheetah design. Although primarily designed for everyday use, the Cheetah Xplore allows the user to engage in various sports and activities without changing the prosthesis. By openly discussing your ambitions and lifestyle requirements with your prosthetist while staying informed about new technology, you can be best assured that you are getting the technology to help you keep living life without limitations.