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Below-the-Knee Prosthetics

A below-the-knee or trans-tibial amputation is the level of amputation where the tibia and fibula ,the two bones in the lower part of your leg, are transected. You still maintain a functioning knee joint. Weight-bearing is achieved by total contact and gently applying pressure at specific pressure tolerant anatomical landmarks of the residual limb.

The prosthesis is attached to your leg with suspension. Insurance, individual characteristics of your limb,and your personal preference are all taken into consideration when deciding on your method of suspension.

Types of suspension

  • Locking pin – A pin is attached to your liner, which engages a lock at the bottom of the socket.
  • Suction – Creates an air-tight seal with a suspension sleeve on the outside of the socket.
  • Vacuum – Actively draws out the air in the socket to keep your leg securely in the socket.

Below-the-knee prosthesis is comprised of four main parts:

  1. Socket – The socket is the term for what your limb will fit into. It is a very important part of your prosthesis as it is what supports your weight.
  2. Liner – The liner is rolled onto your limb and provides a gel-like cushioned and protective layer between your skin and the socket. They can be made of silicone, urethane and thermoplastic elastomer (TPE). Socks allow you to adjust the fit of your prosthesis as your limb size changes throughout the day.
  3. Pylon – The pylon is the shin like portion of your prosthesis that connects the socket to the foot.
  4. Foot – There are many different types of prosthetic feet. Most are made with carbon fiber and are designed for different functions depending on your activity level, hobbies and overall needs.