How are Prosthetic Legs Made?


Evaluation

Research has shown that the earlier a person‘s prosthesis is fitted, the shorter their rehabilitation tends to be.

The first step will be a thorough evaluation with your prosthetist.  He or she will review your physical condition, specifically the condition of your residual limb and whether it has healed sufficiently to accommodate the pressures of the prosthesis on your skin.

The evaluation also will include questions that will help your prosthetist learn about your current lifestyle as well as your goals and ambitions. Your answers will help your prosthetist decide what types of components to include in the design of the best prosthetic leg for you.

Capturing the shape of the residual limb

The next step for the prosthetist is to capture the shape of your residual limb and take measurements for the prosthesis. This may happen during the initial evaluation or during a follow-up session. This is almost like developing a custom mold for your residual limb. It can help ensure that a well-fitting, comfortable socket can be designed.  It is vitally important to capture the shape accurately. Soft tissue can change shape when pressure is applied, which makes this one of the most challenging aspects of the prosthetist’s job.

Your prosthetist might use a variety of ways to capture the shape of your residual limb, including casting directly on the residual limb with an air pressure system, or by using digital scanners.

Fitting the diagnostic socket

Using the custom mold made from your residual limb, your prosthetist will create a test socket to evaluate whether that shape will fit your residual limb comfortably.

The diagnostic socket, which is made from a transparent plastic material that is heat malleable and not intended for permanent use, is typically fitted at the following appointment. Once you and your prosthetist feel satisfied with the design and comfort of your diagnostic socket, the prosthetic components will be assembled and aligned for you in a standing position. This process is called "static alignment."  

If the result is a stable, comfortable prosthesis, you should soon be able to take your first steps. Be sure to have somebody capture a video or photos of your first steps because you will want them later!

Learning to walk

Taking your first steps is a learning experience and an important part of the journey to reach your own potential. There is no need to rush as you learn to use and trust your prosthesis. Many people experience some pain and discomfort as they become accustomed to walking on a prosthetic leg, but as your limb heals, walking should become increasingly more comfortable.

Early gait training is essential. Learning to walk on a prosthetic leg requires you to adopt new techniques. It is far better to develop a good walking technique from the outset than to try to correct an inefficient technique later.

Your physical therapist, assisted by your prosthetist, will recommend special exercises aimed at training the specific muscles needed to walk with your prosthesis.

Fitting the final prosthesis

The fitting and manufacturing of the prosthesis is both a science and an art. The two most important aspects of a good prosthesis are the design of a well-fitting socket with optimal suspension and the correct alignment of the prosthetic components in relation to the residual limb. A good prosthetist always takes special care to make a socket that fits your residual limb perfectly and ensures that the components are aligned correctly.

Your residual limb will continue going through a process of healing and changing shape as it stabilises over time. The muscles in the limb will atrophy (shrink) since they aren't functioning the way they used to, and you may gain or lose weight.

Because your residual limb will continue to change shape, your socket will, at some point, no longer fit perfectly. An ill-fitting socket may move around, which could have a negative effect on aspects like your safety, energy output and comfort. There are ways to manage this temporarily, for instance by putting extra socks over your residual limb, but eventually a new, correctly fitting socket must be made.

Follow-up

Although the definitive socket should fit properly for much longer than the initial, temporary socket(s), you'll have to get updated sockets made at regular intervals in future.

Some adjustments may also be needed as your ability and activity increase and your body adjusts and changes. The interval between each new socket is difficult to predict and varies from patient to patient, but typically most amputees use a device for three years before seeking a replacement.