Amputee Resources: Liner Basics 101 | Lesson 2

What Does a Socket Do?

A socket is the most outer and rigid component of your prosthetic system. It plays a major role in ensuring the comfort and health of your residual limb by providing shape and support to the limb. Because it aids in weight transfer and distribution, if it isn’t fitted correctly, it can cause pain, lesions, sores, or other problematic issues for your residual limb.

Liners & Sockets: A History

Prior to liners, wool socks were the only barrier that existed between a residual limb and a socket. A sock! That’s all that protected your limb!

There were several problems with using wool socks. When washed, they got hard, worn, and uncomfortable quickly. Additionally, wool socks didn’t stay put, they would roll down, twist around, and frequently move out of position.

These socks didn’t provide much support or protection. As such, all limb shapes had to be the same shape as sockets. Easy if all limbs were shaped like ovals, but as we know, this isn’t the case.

The advancement to liners allowed for the fabrication of a skin-socket barrier that could be designed to accommodate the residual limb instead of the socket. Remember, a liner profile is the pattern of thickness of interface material throughout the inside of liner that makes wearing the liner more comfortable for you.

Profiles represent the shape of the residual limb more closely inside of the liner, whereas the outside of the liner looks more oval-shaped. Due to this, all liners appear to be the same shape from the outside; however, the profile of the inside of the liner is what differentiates them. A liner’s profile can be seen in its truest form four inches from the distal end of the liner.

Transtibial Liner Profiles

Due to the complexity of transtibial amputations and surgeries, there are several profile options for transtibial amputees.

Uniform

• Same material dimensions from knee to distal end
• Liner shape is less flared out
• Protection is provided down the front of the liner where the shin is and the back of the liner

Tapered

• Same features as the Uniform profile with additional thickness around the bottom half of the liner
• Conical shape–The interior of the liner narrows as it moves down due to the changing thickness of the interface material
• Extra material is used to create the internal conical shape

Contoured

• Same features as Uniform shape with additional material on either side of shinbone
• Suited for a prominent shin that needs cushioning

Progressive

• A combination of Uniform, Tapered, and Contoured profiles
• Protection is provided down the front of the liner over the shinbone
• Protection at the distal end to provide extra support
• Will accommodate most residual limb shapes

For information on transfemoral profiles, be sure to check in next month for our upcoming installment of Liner Basics 101!

NOTE: Always contact your clinician for prosthetic care advice. The descriptions provided are available to help you get started in choosing which option may be best suited for you, but should never replace prosthetic advice from your clinician.