How Does a Prosthetic Leg Work?

how prosthetic leg works

Perhaps you’ve already decided that a prosthetic leg is the best solution to help you reach your goals, or maybe you’re just starting to consider the idea. Either way, you’ve probably wondered how a prosthetic leg works. The technology behind today’s prosthetics is quite amazing.

Location of the amputation

Understanding how a prosthetic leg works first depends on the location of the amputation itself. In regards to prosthetic legs, the location of the amputation affects how the leg will work. For instance, an above knee amputation and below the knee amputation will require different prosthetic pieces – specifically a prosthetic knee.

For prosthetics involving a joint, special pieces will be required.

  • Powered: A knee joint can be powered in which electric power can assist the prosthetic knee during movement. These knees sense a person’s gait and where the knee is in the gait cycle. With that information, the knee can become more stable, swing freely, or a combination of the two. It takes away some of the thought the patient needs to put into their walking and lets them walk as if the leg were their own. Advances are continued to be made in biomimetic power, in which the body’s electrical impulses can help control limbs.
  • Other devices: A Medi OFM2 Knee allows the knee to lock (while an individual stands) but also unlock as soon as the individual shifts his weight in order to walk.
medi ofm2 knee

A Medi OFM2 mechanical monocentric knee joint with brake function and optional manual lock

Components of a prosthetic leg

Luckily modern technological advances have made huge strides in the components of prosthetic legs. While history shows us that prosthetics used to be made of wood or iron, today’s pieces are constructed of the newer, more durable, and even lighter materials such as carbon-fiber composites. Additionally, using the newest materials can also help limbs in the cosmetic department.

orion 3 microprocessor knee with rush foot

Here’s an Orion 3 microprocessor knee with a rush foot that we fit for patients

So, what are the parts of a prosthetic leg?

  • Pylon: This is the structural support – the component that links the socket with the prosthetic foot. This piece must be solid and durable to support the individual as s/he bears weight on the prosthetic leg.
  • Socket: Often dubbed the most important part of the prosthetic leg, the socket is what surrounds the residual limb, what makes the prosthetic leg “fit” onto the limb. This is custom made to each patient. Without a socket that fits well, one will never be able to walk comfortably or naturally.
  • Suspension system: Have you ever wondered how a prosthetic leg stays firmly attached during use yet can be removed each night at home? The suspension system is responsible for that! Suction and vacuum suspension systems work by creating a seal in which air pressure holds the socket in place.


Getting fit for a custom prosthetic leg is a long process, but understanding the process helps understand how the legs work so well.

  1. Once the amputation takes place and the leg begins to heal, a prosthetist will take a mold (or in some cases, digital measurements) of the residual limb. Why does a mold help a prosthetic leg work better? Because the prosthesis is built according to the mold/measurements, the prosthetic leg will fit that much better.
  2. Physical therapy: Not only will physical therapy help you learn to walk with your new prosthesis, but it will help you understand how the leg works and your body can work with it.
  3. Adjustments: This is the most critical step because a good experience with a prosthetic leg is dependent on an appropriate fit of the socket. An ill-fitting prosthesis is uncomfortable and hard to maneuver.

Watch the video below as our practitioner, Rob Huddler, fits a patient for a new prosthetic leg after picking him up at the train station!

Have more questions? Feel free to contact Advantage Prosthetics and Orthotics today!


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