There are many different types of suspension systems that are used to suspend a prosthesis. The suspension system of a prosthesis is a crucial factor in the design of a prosthesis. The suspension is how the socket is held to the residual limb. Good suspension will improve control of the prosthesis, limit movement within the prosthesis and decrease any discomfort or abrasions. When suspension is poor the leg may feel heavy and could lead to skin breakdown. There are many different types of suspension options.
Often the question is asked “what is the best suspension type?”. Suspension type is determined during the initial assessment with your prosthetist. Many factors are taken into consideration to determine an appropriate suspension, such as; skin condition, mobility or activity level, hobbies, hand strength/dexterity, goals, cognition, vision, etc. The suspension type that is best for you may not be the same as another person. Your WinPO prosthetist will discuss the pros and cons of the options available and work with you to determine what is best.
All systems will secure the residual limb inside the prosthetic socket and allows for the process of putting the prosthesis on (donning) or taking the prosthesis off (doffing). Here we will look at three different systems that are frequently used.
Sleeve Suspension System
The sleeve is a gel like tube that rolls over the knee and onto the thigh. This creates a vacuum like seal providing “negative pressure” or a “passive vacuum” type of environment of the limb within the socket of the prosthesis. The sleeve physically holds the prosthesis on while also sealing in the air within the socket to create an intimate fit and is a very good suspension system. Sleeves are made from different materials, primarily silicone or copolymer gel. When donning the prosthesis users are instructed to don their residual limb all the way into the socket before rolling up the sleeve. This will decrease any trapped air and minimize movement of the residual limb within the socket. The lifetime of the sleeve varies depending on use. A slight hole in the sleeve will allow air into the socket and allow for movement of the residual limb which could cause pain or discomfort.
Pin Lock Suspension System
Pin lock suspension systems typically work best with residual limbs that are cylinder-shaped. Similar to the sleeve suspension system, a liner made of silicone or gel is used, the difference is the sleeve will have a pin on the end of it that locks into the bottom of the prosthetic socket. Using a pin lock system does take a little more effort and care must be taken to ensure that the right number of prosthetic socks are used, if the pin clicks in too easily, more socks may need to be added. To remove the prosthesis a release button that is on the side of the socket is pushed and held while the prosthesis is pushed off.
This suspension method requires a sealing membrane, which is attached to or used with a liner. In some cases, skin suction is also an option? When donning the prosthesis, the seal presses against the socket wall and a one way-value expels the air out of the socket below the seal. This will create a negative pressure below the seal suspending the prosthesis. To doff the prosthesis, pressing a one way valve’s release mechanism will allow air into the socket which will help to break the sealing membrane from the socket wall. Press this release while pushing off the socket/prosthesis. It is important to keep the sealing membrane and the interior aspect of the socket clean. Any debris (even a single hair) can prevent a proper seal/ suction.
Thankfully, when it comes to suspension systems with your prosthetics you will not need to make this decision on your own. Your Prosthetist will be able to guide you on what system will work best for you!