What keeps the prosthesis from falling off?
This is a very good question, and an important one. The more securely a prosthesis stays on a person’s residual limb, and with the person as they move, the more useful it will be.
What keeps the prosthesis on a person’s residual limb is called the method of suspension. There are many methods of suspension for both upper and lower extremity prostheses. We work with each individual to select the most suitable suspension method(s) for their activities, physiology, and goals.
A few common suspension methods are described here:
Pin-Liner – A prosthesis may be suspended through a mechanical lock. In this method, a gel-liner is worn over the residual limb that contains a metal pin. When donning the socket/prosthesis, this metal pin clicks into a lock that is built into the socket creating a safe and secure mechanical link between the residual limb and prosthesis. This method is available for upper (arm) and lower limb (leg) prostheses.
Suction Liner – A prosthesis can be suspended through vacuum suction. In this method, a gel-liner is worn over the residual limb. The socket will contain a one-way valve that allows air to exit, but not re-enter the socket, creating a more intimate and secure socket fit with each step. For above-knee prostheses, this liner will contain a silicone ring that creates a vacuum seal inside the socket. For below-knee prostheses an additional suspension sleeve (similar to a neoprene knee brace) is worn. After the prosthesis is donned, this sleeve is rolled up to create a seal between the liner and the sleeve.
Harness/Belt – A lower-limb prosthesis may be held on with a waist belt, worn under the clothing, which is attached to the prosthesis to hold it up. Upper-limb prostheses can also be suspended with a harness system that loops around the shoulders and under the opposite armpit.
There are many other suspension options available. We will explore the most appropriate suspension method(s) with you, and select the best system for you and your activities.