Gait Analysis
Maryam Hajizade; Alireza Hashemi Oskouei; Farzan Ghalichi; Farhad Tabatabai Ghomshe; Mohammad Razi; Gisela Solo
Volume 9, Issue 1 , April 2015, , Pages 17-31
Abstract
Patients with ACL deficiency (ACLD) have to use different compensatory mechanisms to maintain their stability during daily activities. The aim of this study is to determine the differences in 3D kinematics and peak ground reaction forces (GRF) between ACL deficient legs and healthy contralateral legs ...
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Patients with ACL deficiency (ACLD) have to use different compensatory mechanisms to maintain their stability during daily activities. The aim of this study is to determine the differences in 3D kinematics and peak ground reaction forces (GRF) between ACL deficient legs and healthy contralateral legs during stair ascent. Eight subjects with unilateral ACL deficiency participated in this study. Healthy contralateral legs were considered as control group for further comparisons to ACL deficient legs. A six camera VICON motion analysis system and 2 portable force plates were used to record the locomotion while walking up custom-made stairs with two different step heights. Advanced OSSCA technique was used to assess tibiofemoral knee kinematics, a combination of symmetrical axis of rotation (SARA), symmetrical center of rotation estimation (SCoRE) and optimal common shape technique (OCST). The results of this study show that participants with ACLD experienced different kinematics and peak GRFs in different step heights (p<0.05). During ascending stairs with 17cm height, legs with ACLD exhibited less varus, more external rotation and less impact peak in pre-swing stance and early swing phase compared to contralateral healthy leg (p<0.05). The other stair height, 20 cm, resulted in more extension, more valgus and more external tibia rotation in injured leg compared to contralateral leg during terminal extension of stance phase (p<0.05). In both step heights, injured leg reached it maximum extension peak at an earlier time. The results of this study imply that participants with ACLD make use of different 3D rotational tiobiofemoral kinematics and different GRF compared to healthy contralateral leg. These compensatory mechanisms would finally bring about different knee joint loading, which provides the potential of cartilage degeneration and early osteoarthritis.
Cell Biomechanics / Cell Mechanics / Mechanobiology
Farhad Tabatabaei Ghomshe; Ahmad Reza Arshi; Masoud Mahmoudian; Mahyar Janahmadi
Volume -1, Issue 1 , June 2004, , Pages 77-92
Abstract
Effective pharmacological analysis encompassing both the pharmacodynamics and the pharmacokinetics of the heart, dictates the necessity for responses made by the main channel receptors, to be appropriately modelled. This approach is of critical value when the pharmacological responses of the organ during ...
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Effective pharmacological analysis encompassing both the pharmacodynamics and the pharmacokinetics of the heart, dictates the necessity for responses made by the main channel receptors, to be appropriately modelled. This approach is of critical value when the pharmacological responses of the organ during pathological states are under investigation. To this effect, the electrochemical phenomenon in the heart was simulated using a specifically simplified three dimensional model based on the cellular physiological concepts. Various advanced models for different types of heart cells were combined to produce a three dimensional model capable of describing the electrophysiological, electrochemical and geometric characteristics of a heart in a non-pathological state. Various cell type models such as central and peripheral SA node, AV node, atrial myocyte, ventricular myocyte, and specialized cells for rapid conductance like purkinje fibres were included in the 3D model. The cellular architecture in the model follows the non-heterogeneity of the heart structure accompanied by gap junctions representing cellular interconnections. Here the transport of Na+, Ca++, K+ and CL- was primarily governed by such factors as electrical and chemical potential gradients along with other energetic mechanisms. The simplified heart geometry is introduced through 18 layers with 25 cells in each layer. Model equations were solved to simulate a one second using a 2.6 GHz Pentium IV PC. The simulation was performed utilizing MA TLAB programming language which provides effective visualization capabilities. The CEP model could be adopted as a preliminary basis towards individualizations in pharmacology and electrophysiology.