Coordinated Planar Mechanisms to Approximate the Three Dimensional Motion of the Knee

2009 ◽  
Vol 3 (3) ◽  
Author(s):  
Daniel Nielsen ◽  
Loren Blocker ◽  
Nick Pardo
Keyword(s):  
Three Dimensional ◽  
Motion Generation ◽  
Complex Motion ◽  
Planar Mechanisms ◽  
Single Degree Of Freedom ◽  
Human Knee ◽  
Human Knee Joint ◽  
Analytical Strategies ◽  
Operational Envelope ◽  
Flexion And Extension

The motion of the human knee during flexion and extension generates spatial movement. The current designs of many knee braces and prostheses fail to incorporate this complex motion. This paper presents a method for developing mechanisms with which to more accurately approximate the true movement of the human knee joint with an orthosis comprised of single degree of freedom (DoF) mechanisms. Digitized measurements of the relative motion of the tibia and femur were used to determine the design positions of the mechanisms. Analytical strategies were employed to synthesize suitable Stephenson six-bar linkages for the task of motion generation. The more desirable solutions were selected based on their ability to match the measured movement of the knee as well as the size of their operational envelope. Distinct, single DoF linkages were synthesized for the medial and lateral sides of the knee. Coordination, via attachment to the tibial portion of the orthosis, of these linkages provides a single DoF mechanism to approximate the complex motion of the tibia relative to the femur during flexion and extension.

Studying the Intact, ACL-Deficient and Reconstructed Human Knee Joint Using a Finite Element Model

2013 ◽  
Author(s):  
Achilles Vairis ◽  
Markos Petousis ◽  
George Stefanoudakis ◽  
Nectarios Vidakis ◽  
Betina Kandyla ◽  
...  
Keyword(s):  
Finite Element ◽  
Knee Joint ◽  
Cruciate Ligament ◽  
Three Dimensional ◽  
Element Model ◽  
Human Knee ◽  
Mechanical Responses ◽  
Human Knee Joint ◽  
Calculated Load ◽  
Anterior Cruciate

The human knee joint has a three dimensional geometry with multiple body articulations that produce complex mechanical responses under loads that occur in everyday life and sports activities. Knowledge of the complex mechanical interactions of these load bearing structures is of help when the treatment of relevant diseases is evaluated and assisting devices are designed. The anterior cruciate ligament in the knee connects the femur to the tibia and is often torn during a sudden twisting motion, resulting in knee instability. The objective of this work is to study the mechanical behavior of the human knee joint in typical everyday activities and evaluate the differences in its response for three different states, intact, injured and reconstructed knee. Three equivalent finite element models were developed. For the reconstructed model a novel repair device developed and patented by the authors was employed. For the verification of the developed models, static load cases presented in a previous modeling work were used. Mechanical stresses calculated for the load cases studied, were very close to results presented in previous experimentally verified work, in both load distribution and maximum calculated load values.

MEASUREMENT AND FITTING ON 3-D ARTICULAR SURFACES OF THE HUMAN KNEE JOINT

2002 ◽  
Vol 14 (04) ◽  
pp. 171-174
Author(s):  
XISHI WANG ◽  
LI-QUN ZHANG
Keyword(s):  
Knee Joint ◽  
Three Dimensional ◽  
Reconstruction Error ◽  
Reconstruction Procedure ◽  
Human Knee ◽  
Articular Surfaces ◽  
Human Knee Joint ◽  
Surface Measurements ◽  
Articulating Surface ◽  
Relative Analysis

In this study, the OptoTrak system was employed to collect the articulating surface measurements of the human knee for the femur, tibia and patella in three experimented specimens. Furthermore, a rigorous mathematical reconstruction procedure that estimates reconstruction error was completed by employed the relative analysis tools. The results show, the measurements for each session were able to reconstruct the three-dimensional calibration to a precision of 0.02mm. On the other word, the OptoTrak can be used to obtain the precise measurements of analytical surface of the human knee joint.

Performance Maps for a Bio-Inspired Robotic Condylar Hinge Joint

2014 ◽  
Vol 136 (11) ◽  
Author(s):  
Stuart C. Burgess ◽  
Appolinaire C. Etoundi
Keyword(s):  
Design Space ◽  
Three Dimensional ◽  
Design Parameters ◽  
Mean Square ◽  
Cruciate Ligaments ◽  
Range Of Movement ◽  
Mechanical Advantage ◽  
Human Knee ◽  
Hinge Joint ◽  
Human Knee Joint

This paper presents performance charts that map the design space of a bio-inspired robotic condylar hinge joint. The joint mimics the design of the human knee joint by copying the condylar surfaces of the femur and tibia and by copying the four-bar motion of the cruciate ligaments. Four aspects of performance are modeled: peak mechanical advantage, RMS (root mean square) mechanical advantage, RMS sliding ratio, and range of movement. The performance of the joint is dependent on the shape of the condylar surfaces and the geometry of the four-bar mechanism. The design space for the condylar hinge joint is large because the four-bar mechanism has a very large number of possible configurations. Also, it is not intuitive what values of design parameters give the best design. Performance graphs are presented that cover over 12,000 different geometries of the four-bar mechanism. The maps are presented on three-dimensional graphs that help designers visualize the limits of performance of the joint and visualize tradeoffs between individual aspects of performance. The maps show that each aspect of performance of the joint is very sensitive to the geometry of the four-bar mechanism. The trends in performance can be understood by analyzing the kinematics of the four-bar mechanism and the shape of the condylar surfaces.

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