Development of a Low Cost Prosthetic Swing-Phase Mechanism

Authors

  • Alex Furse University of Toronto IBBME Bloorview Research Institute
  • Jan Andrysek University of Toronto IBBME Bloorview Research Institute
  • W. L. Cleighorn University of Toronto IBBME Bloorview Research Institute

Abstract

Although a number of accessible low cost prosthetic devices have been developed most only provided basic function and lack technology that assist the patient during swingphase. A prosthetic swing phase mechanism simulates the action of the upper leg musculature to aid in increased gait function. More specifically, swing-phase mechanisms limit the maximum knee flexion and allow the shank to smoothly decelerate into full extension without impact. Six above-knee amputees were fitted with a low-cost prosthetic knee and different low-cost swing-phase setups were clinically assessed. Clinical testing included 20-meter walk tests utilizing a mobile computer setup connected to potentiometers (measure knee flexion angle and time) and accelerometers (measure terminal impact accelerations) mounted on the prosthetic limb. As hypothesized, incorporating friction and a spring system showed improved gait function. The dual spring system, two springs in series, as predicted by a computational model and mechanical testing out performed the single spring system. The swing phase knee torque versus flexion pattern of the novel design best matched hydraulic baseline data. Clinical trials displayed increased velocity with decreased maximum flexion and terminal impact when dual springs were incorporated. The deactivation of the stiff spring and activation of the less stiff spring during the last 20 degrees of swing-phase before extension allows the shank to decelerate and hit the extension bumper at a lower velocity. The new dual spring mechanism is simple, improves prosthetic function, and is ideal for use in low-cost and peadiatric prostheses, where size and cost may be constrained.

Author Biographies

Alex Furse, University of Toronto IBBME Bloorview Research Institute

Department of Mechanical and Industrial Engineering

Jan Andrysek, University of Toronto IBBME Bloorview Research Institute

Doctor, Department of Mechanical and Industrial Engineering

W. L. Cleighorn, University of Toronto IBBME Bloorview Research Institute

Professor, Department of Mechanical and Industrial Engineering

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Published

2010-06-15

How to Cite

[1]
A. Furse, J. Andrysek, and W. L. Cleighorn, “Development of a Low Cost Prosthetic Swing-Phase Mechanism”, CMBES Proc., vol. 33, no. 1, Jun. 2010.

Issue

Section

Medical Devices