The various components of a prosthetic leg

Are you about to be fitted for a prosthesis for the first time? It may seem as if you’re going to receive a simple device, but nothing could be further from the truth. A prosthesis consists of a number of different components. What are they and what do they do?

Every prosthetic leg has a socket, a foot, connecting elements (called adapters) and often a cosmetic cover. A prosthesis may also include a prosthetic knee and hip joint, depending on the amputation level. Read our article on the different leg amputation levels.

Below we explain the various components that may make up your prosthetic leg and which you will hear your O&P professional talk about:

The socket fits around and protects the residual limb. The other prosthesis components are attached to it. It is made of various types of synthetic resins that are reinforced with carbon. The socket transfers the forces between the residual limb and the prosthesis.

The liner connects your residual limb with the prosthetic socket and has a significant impact on the wearing comfort of your prosthesis. It is a cover made of plastic or silicone that is rolled over the residual limb like a sock and has a thickness of around three to five millimetres. The liner ensures optimal pressure distribution across the residual limb and attachment of the prosthesis. When a load is applied to the residual limb when standing and walking, the liner also protects the skin. Some liners release an oily substance onto the skin, keeping it smooth. Liners can be made of silicone, polyurethane or copolymer.

More information: 3 types of liners for leg prostheses

The adapter is an attachment piece for the various components of the prosthesis. It makes it easy to position the different parts accurately in relation to one another. Proper alignment of a prosthesis has a significant impact on the energy that is required when wearing a prosthesis.

Nowadays, there are a wide range of different knees available, more than ever before. The knee joint chosen must be a good fit for your daily life. Every knee type has its benefits, but there are also limitations to what the knee can do. So, make sure to be well informed about all the possibilities and limitations of the various types of knees before deciding. Consider, for example, the performance of the prosthetic knee joint in various types of terrain, slopes and stairs. And what are the effects of water, dirt, vibrations and electric and magnetic disturbances?

A unique prosthesis is the microprocessor-controlled knee (MPK). This is a hydraulic prosthetic knee in which bending and stretching is supported or inhibited using computer technology. If you are considering this prosthesis, ask your O&P professional about exposure to water, guarantees, service options and how the knee functions with a dead battery. Read more about it in our article about osseointegration and a microprocessor-controlled knee.

You can also choose different types of knees for different activities. Again, your O&P professional can explain all the possibilities. 

With a prosthetic leg, you can choose to have a cosmetic cover with a natural or high-tech appearance. Apart from choosing your preferred look and feel, the cover also ensures a leg volume that is equivalent to the healthy leg. The cover is not added to the prosthesis until the final stage.

The ‘natural’ cover is made of foam and available in different skin tones. The O&P professional will attempt to achieve a leg volume that is as natural as possible. However, a cosmetic cover is not the same as an anatomically shaped silicon leg cover. This type of cover is fully customised and has a lifelike look and feel.

More and more people are opting for a high-tech design with a plastic cover. These covers protect the (more high-tech) prostheses from damage and wear. The cover is customised to the prosthesis, so that the prosthesis retains its freedom of movement.

Whichever type of prosthetic leg is chosen, it always includes a prosthetic foot. The foot is designed to imitate the human foot function. If a person is no longer mobile, the function of the prosthetic foot is primarily cosmetic, so the foot should look like a ‘real’ foot. Most people never see their prosthetic foot without the cosmetic foot cover, i.e. the outside.

The foot cover serves two important functions: it helps your prosthetic foot look like a "regular" foot and it fills the space in your shoe. Various skin tones and sizes are available. The simpler foot covers often have fewer details, such as toes, while high-quality foot covers often have more lifelike skin tones and toes.