scholarly journals Effect of Relative Marker Movement on the Calculation of the Foot Torsion Axis Using a Combined Cardan Angle and Helical Axis Approach

2012 ◽  
Vol 2012 ◽  
pp. 1-6 ◽  
Author(s):  
Eveline S. Graf ◽  
Ian C. Wright ◽  
Darren J. Stefanyshyn
Keyword(s):  
Helical Axis ◽  
Minimal Amount ◽  
Accurate Calculation ◽  
Reference Location ◽  
Probability Score ◽  
Human Foot ◽  
Torsion Axis ◽  
Metatarsophalangeal Joints ◽  
Finite Helical Axis

The two main movements occurring between the forefoot and rearfoot segment of a human foot are flexion at the metatarsophalangeal joints and torsion in the midfoot. The location of the torsion axis within the foot is currently unknown. The purpose of this study was to develop a method based on Cardan angles and the finite helical axis approach to calculate the torsion axis without the effect of flexion. As the finite helical axis method is susceptible to error due to noise with small helical rotations, a minimal amount of rotation was defined in order to accurately determine the torsion axis location. Using simulation, the location of the axis based on data containing noise was compared to the axis location of data without noise with a one-samplet-test and Fisher's combined probability score. When using only data with helical rotation of seven degrees or more, the location of the torsion axis based on the data with noise was within 0.2 mm of the reference location. Therefore, the proposed method allowed an accurate calculation of the foot torsion axis location.

Average Torsion Axis Location of Athletic Movements: Subject Specific or Movement Specific?

2013 ◽  
Vol 29 (3) ◽  
pp. 365-368 ◽  
Author(s):  
Eveline S. Graf ◽  
Darren J. Stefanyshyn
Keyword(s):  
Rotation Axis ◽  
Helical Axis ◽  
Torsion Angles ◽  
Torsion Element ◽  
Human Foot ◽  
Subject Specificity ◽  
Significant Difference ◽  
The Subject ◽  
Torsion Axis ◽  
Finite Helical Axis

Foot torsion angles have previously been studied for different athletic movements. Sport shoes often contain a torsion element even though the location of the rotation axis of the foot is unknown. Therefore, the purpose of this study was to quantify the torsion axis location and determine if the location is influenced by the movement or the subject. The torsion axis location was calculated using a modified finite helical axis approach, which allowed the calculation of the rotation axis between the forefoot and the rearfoot without the influence of forefoot flexion. The torsion axis location during the lateral jab was 9.72 mm below and 26.96 mm lateral to a marker located at the posterior, central heel, whereas the shuffle cut resulted in an axis location of 9.59 mm below and 26.19 mm lateral to the reference marker. There was no significant difference for the average axis location between movements. There was, however, a significant difference for the location between subjects, indicating a subject specificity of the torsion axis. The results of the current study are the first to quantify the torsion axis location of the human foot during athletic movements.

Use of the alpha shape to quantify finite helical axis dispersion during simulated spine movements

2016 ◽  
Vol 49 (1) ◽  
pp. 112-118 ◽  
Author(s):  
Stewart D. McLachlin ◽  
Christopher S. Bailey ◽  
Cynthia E. Dunning
Keyword(s):  
Helical Axis ◽  
Alpha Shape ◽  
Finite Helical Axis

Knee Joint Motion Quantified Using the Finite Helical Axis Method

2007 ◽  
Author(s):  
Ingrid R. Fjeld ◽  
Jessica C. Küpper ◽  
Janet L. Ronsky ◽  
Richard Frayne
Keyword(s):  
External Rotation ◽  
Cruciate Ligament ◽  
Cartilage Degeneration ◽  
Helical Axis ◽  
Joint Motion ◽  
Stable Manner ◽  
Knee Joint Motion ◽  
Anterior Cruciate ◽  
Complex Joint ◽  
Finite Helical Axis

The knee is a complex joint comprised of two main bones (femur and tibia) that articulate in a stable manner through the support of surrounding meniscus, musculature, and ligaments. The anterior cruciate ligament (ACL) is one of the main ligaments connecting the femur to the tibia. The ACL restricts anterior translation of the tibia with respect to the femur and aids in preventing internal and external rotation. The ACL is the most commonly injured ligament in the knee [1] and has been shown to increase the risk of cartilage degeneration leading to osteoarthritis (OA) [2]. The mechanics of the joint are altered following an ACL rupture, but the relations between the resulting joint instability and OA are not well understood.

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