Basic prosthetic knees represent a class of knee joints that do not incorporate microprocessors, real-time sensors, hydraulic resistance, or fluid cylinders. These simpler knee mechanisms are intended for those who walk at a single walking speed and are often smaller and lighter than more advanced knee options.
A primary distinction among basic knees is whether they are single-axis or multi-axis (also called polycentric or four bar).
Single-axis knees are built with a single hinge point. This type of knee is both durable and lightweight, but offers a limited range of adaptability to different gait speeds. It uses an adjustable friction setting to prevent the leg from swinging forward too fast, allowing for one optimal walking speed. Most single-axis knees include the ability to lock the knee in place for standing or walking when the user requires additional security in their prosthesis.
Polycentric knees bend through multiple hinge points, making it less likely that the knee will buckle during standing. In some designs, this mechanism will also shorten the prosthesis as it swings beneath the user, reducing the risk of tripping and falling. Polycentric knees can meet the needs of people with varying degrees of activity, with simpler versions better for light activity and more advanced versions better suited to heavy activity.
Your clinician will help you determine which knee is best suited to your unique needs.
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