Suspension Methods for Below Knee Prosthesis in Kansas City
By: Phil Henry, CPO
Prosthetic Suspension systems
Suspension is a term used to describe how the prosthesis stays on the residual limb. A below the knee prosthesis (also known as a Transtibial prosthesis) must maintain proper suspension in order to achieve functional benefit of the device. Poor suspension can lead to secondary gait deviations that cause the wearer to feel unsafe, waist energy to accommodate for lack of suspension, and causes a major fall risk. There are several suspension systems for the below knee prosthesis. Here is a look at some of the commonly used Trans Tibial prosthetic suspension systems.
- Suction- When residual limb is being seated inside the socket, an expulsion valve (one way valve) that expels the air without return. The suction is achieved with use of a seal in gel liner or suspension sleeve. More advanced systems can include a vacuum suction system that expels with more force than that of a expulsion valve.
- Pin lock or locking mechanism- A locking gel liner is used for this mechanism that allows a pin that protrudes at the end of the liner that engages the lock mechanism. Once locked in place, the prosthesis will remain locked until disengaged by a release lever
- Thigh corset and knee joints- typically seen for use in the shorter below knee residual limbs due to the lack of stability, but serves as a suspension option without use of a waist strap and gives a tight circumferential wrap round the thigh
- Cuff suspension strap- Use of a “fork strap” that wraps around the bony prominences of the bottom or distal end of the femur. The capture of the bone allows the strap to rest on once prosthesis is lifted off the ground
- Self-suspending sockets- (also known as supracondylar or supracondylar-suprapatellar suspension) This is use of higher medial/lateral trim lines that can, if needed for more stability, include the knee cap. This system also captures over the bony landmarks of the distal end of the femur. This system does not require a strap or additional component.
The selection of the below knee suspension system is decided by the Prosthetist. Each suspension system will usually have a pro and a con and should be discussed in detail with the treating Practitioner on which suspension system is best for you.
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