Knee Brace Cam-Link Mechanism for Flexion-Contracture Pain
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Solution Overview
Problem
Knee joint flexion contracture causes pain during extension due to inhibited sliding between the femoral condyle and the upper joint surface of the shinbone, making rehabilitation challenging.
Innovation Solution
A knee brace with a thigh and shank attachment, featuring outer and inner units with rotatable links and cams, allows for the shinbone to be pulled downward and forward during extension, maintaining an appropriate joint alignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the knee joint is extended in a state of flexion contracture, then the range of motion is expanded, but pain occurs due to inhibited sliding between the femoral condyle and the shinbone joint surface
Solution Approach 1:
The knee brace applies preliminary action by using cam mechanisms to protract the shinbone forward and create a gap between the femoral condyle and shinbone joint surface before extension occurs. This preliminary positioning prevents the inhibited sliding and pain that would otherwise occur during extension, allowing the user to safely expand their range of motion without experiencing pain.
Solution Approach 2:
The knee brace acts as an intermediary device between the user's knee joint and the external environment. The cam mechanisms and linkages mediate the extension motion by controlling the relative positions of the femur and shinbone, ensuring that the joint surfaces slide appropriately while preventing harmful contact or misalignment during the extension process.
2Stability of the object's composition
If the upper joint surface of the shinbone is displaced rearward relative to the femoral condyle, then flexion contracture is maintained, but sliding between joint surfaces is inhibited causing pain during extension
Solution Approach 1:
The knee brace performs preliminary action by using the cam mechanisms to advance the shinbone forward and create proper joint alignment before extension begins. This preliminary positioning corrects the rearward displacement characteristic of flexion contracture, ensuring that the femoral condyle and shinbone joint surface are properly aligned to allow pain-free sliding during extension.
Solution Approach 2:
The knee brace applies parameter changes by dynamically altering the relative position and orientation of the shinbone with respect to the femur during motion. The cam mechanisms change the positional parameters of the joint surfaces, transforming the harmful rearward displacement into the appropriate forward positioning needed for painless extension and proper sliding.
Data Source
AI summary
A shank outer link moves away from a thigh outer link in the longitudinal direction of the shank outer link and the shank outer link is drawn forward in a direction perpendicular to the longitudinal direction of the shank outer link relative to the thigh outer link as a knee joint of a user is extended. A shank inner link moves away from a thigh inner link in the longitudinal direction of the shank inner link and the shank inner link is drawn forward in the direction perpendicular to the longitudinal direction of the shank inner link relative to the thigh inner link as the knee joint of the user is extended.