On Transfemoral Prosthetic Knee Design for Natural Human Knee Motion

Author(s): Wen-Tzong Lee*, Kevin Russell, Raj S. Sodhi.

Journal Name: Recent Patents on Mechanical Engineering

Volume 13 , Issue 1 , 2020

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Background: A transfemoral prosthetic knee is an artificial knee used by above-the-knee amputees. There are two major categories of transfemoral prosthetic knee designs: pin joint-based and polycentric designs. While pin joint-based knee designs only allow pure rotation of the knee, polycentric knee designs allow a combination of rotational and translational knee motion which is exhibited in natural knee motion.

Objective: This work presents both the recently-patented design process and the resulting design of a polycentric transfemoral prosthetic knee that approximates natural spatial human knee motion during flexion and extension.

Methods: The design process includes tibial motion acquisition, Revolute-Revolute-Spherical-Spherical linkage (or RRSS) motion generation, RRSS linkage axode generation and circle fitting. The polycentric transfemoral prosthetic knee design produced from this process includes a gear joint with a specific spatial orientation to approximate natural spatial human knee motion.

Results: Using the design process, a polycentric transfemoral prosthetic knee was designed to replicate a group of five tibial positions over 37.5° of knee flexion (the amount of knee flexion in a standard human gait cycle) with a minimal structural error.

Conclusion: The circular gear-based knee design accurately replicated natural spatial knee motion over the tibial position data given for a standard human gait cycle. The knee design method must be implemented over a broader sampling of tibial position data to determine if a circular gear-based knee design is consistently accurate.

Keywords: Axode generation, circle fitting, four-bar spatial linkage, motion generation, polycentric knee, RRSS linkage, transfemoral prosthetic knee.

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Article Details

Year: 2020
Page: [49 - 59]
Pages: 11
DOI: 10.2174/2212797613666191219154947
Price: $25

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