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Choices for optimization criteria for goal-directed single-joint movements
Abstracts-International
Society of Biomechanics
XII Congress 1989
1081
FINITE-ELENBNT-STUDYOF TliE STe.BILITYOF A PENUR PLATE OSTEOSYNTNESIS. INPLUF,NCE OF THE SCREW DIAHETER AND THE SCREW PLATE CONNECTION K.D. Seide (l), il. Zierold (2),-D. Walter (l), H.R. Kortnann (1) (1) Abteilung ftir Unfall-, Wiederherstellungsund Plastische Chirurgie, Allgemeines Krankenhaus St. Georg, Lohmlhlenstr.5, 2000 Hamburg 1 (Chefarrt Prof. Dr. Walter) (2) Deutsches Elektronen Synchrotron (DESY), Nottkestr., 2000 Hamburg 54 In a 3-dimensional finite-element-model of a segment of a human femur with an attached stainless steel C-hole-plate under the load of the one-legged stance, pressures on the face of the screw holes, bending stresses in the screws and axial bone stresses in the mid-plate transverse section were determined. The calculations were performed for minor thread diameters of 3mm, 5mm and 8mm, comparing a screwhead-plate interface, with possible rotation, and a rigid fixator-type connection. Bone pressures and screw bending stress decreased from beneath the plate in the cortical the values in the opposite thread were one order of magnitude less. Naxinal wall, caused by the large stresses resulted for screw and bone at the end of the plate, difference in E-module between the steelplate and bone. Definitely less stresses in bone and screws combined with an increase in bending stability of the system were found, when the screw thickness was increased. The rigid screw-plate connection yielded about 10 percent less bone stresses when no osteal defect was present. End-plate screws and bone were loaded in excess of their material linits when 3mn core diameters were used under the assumed conditions.
CHOICESFOROPTIMIZATIONCRITERIA FOR GOAL-DIRECTED SINGLE-JOINTMOVEMENTS Amir H. Seif-Naraghi and Jack M. Winters Electrical & Computer Engineering and Chemical, Bio & Materials Engineering Arizona State University, Tempe, AZ 85287 Neuromotor control strategies during goal-directed movements are investigated using optimization methods and an eighth-order, nonlinear antangonistic muscle-joint model structure. A generalized performance criterion is utilized that includes subcriteria that can be divided into two categories: those penalizing kinematic position “errors” or lack of trajectory l’smoothnessV’; and ii) those penalizing neuromuscular “activityV’. It is shown that the relative weights between these two types of subcriteria are task dependent. However, within the neuromuscular “activity” subcriteria category it is suggested that to best approximate a wide variety of experimental data all three of the subcriteria examined within this category, “neural effort*‘, “muscle stress”, and “muscle dissipation”, should be simultaneously penalized. Once normalized, extensive optimization experience suggests relative weight between these of 1, 5 and 5, respectively. These results lay the foundation for a different conceptual approach for optimization: one stressing optimization as a tool for insight into movement strategies rather than as a technique for trying to “prove” or “disprove” a theory for movement.
REHABILITATIONMECHANISMS OF CHILDRENWITH CEREBRAL PARALYSISBY SIMGLTANERVOUS EFFECT OF ELECTRICCURRENTS ANDMAGNETICFIELD ON CHILD NFNMMOTIVESYSTEM Seregin Yu. V., Candidate of Technical Sciences, Assistant Professor, Rovno, Ukraine, USSR Cur experience of using electric and magnetic stimulation m()ans for relsbilitating children with cerebral paralysis has shown that controlling organism responses by simultaneous effect of electric current (EC) and magnetic field (W) on both links of neuromotive system patient& rehabilitation therapeutic effect is achieved tbrou@ organism proper effortsforced in the process of response dmelopmnt to use all its reserves for forming tictional reflex links. As fomation of &&oh links under neuromotive system central link patholw is impossible witbout preliminary lpobllising brain reserves EC and MF action is directed first at forming organimresponse providing conditions for functional activity of preserved or reversibly changed~neurons and then at their optimal use. For developing and controlling the necessary response W.obtalned analytic
dependences
setting
EC and W parameters
permitting
to exercise
discrete
individually measured effects simultaneously on central an&peripheral links of patient& neuromtive system. Studies show no detrimental affect on patient& organism knd provide adequate control of locomotion formation process with 84% positive results.
Society of Biomechanics
XII Congress 1989
1081
FINITE-ELENBNT-STUDYOF TliE STe.BILITYOF A PENUR PLATE OSTEOSYNTNESIS. INPLUF,NCE OF THE SCREW DIAHETER AND THE SCREW PLATE CONNECTION K.D. Seide (l), il. Zierold (2),-D. Walter (l), H.R. Kortnann (1) (1) Abteilung ftir Unfall-, Wiederherstellungsund Plastische Chirurgie, Allgemeines Krankenhaus St. Georg, Lohmlhlenstr.5, 2000 Hamburg 1 (Chefarrt Prof. Dr. Walter) (2) Deutsches Elektronen Synchrotron (DESY), Nottkestr., 2000 Hamburg 54 In a 3-dimensional finite-element-model of a segment of a human femur with an attached stainless steel C-hole-plate under the load of the one-legged stance, pressures on the face of the screw holes, bending stresses in the screws and axial bone stresses in the mid-plate transverse section were determined. The calculations were performed for minor thread diameters of 3mm, 5mm and 8mm, comparing a screwhead-plate interface, with possible rotation, and a rigid fixator-type connection. Bone pressures and screw bending stress decreased from beneath the plate in the cortical the values in the opposite thread were one order of magnitude less. Naxinal wall, caused by the large stresses resulted for screw and bone at the end of the plate, difference in E-module between the steelplate and bone. Definitely less stresses in bone and screws combined with an increase in bending stability of the system were found, when the screw thickness was increased. The rigid screw-plate connection yielded about 10 percent less bone stresses when no osteal defect was present. End-plate screws and bone were loaded in excess of their material linits when 3mn core diameters were used under the assumed conditions.
CHOICESFOROPTIMIZATIONCRITERIA FOR GOAL-DIRECTED SINGLE-JOINTMOVEMENTS Amir H. Seif-Naraghi and Jack M. Winters Electrical & Computer Engineering and Chemical, Bio & Materials Engineering Arizona State University, Tempe, AZ 85287 Neuromotor control strategies during goal-directed movements are investigated using optimization methods and an eighth-order, nonlinear antangonistic muscle-joint model structure. A generalized performance criterion is utilized that includes subcriteria that can be divided into two categories: those penalizing kinematic position “errors” or lack of trajectory l’smoothnessV’; and ii) those penalizing neuromuscular “activityV’. It is shown that the relative weights between these two types of subcriteria are task dependent. However, within the neuromuscular “activity” subcriteria category it is suggested that to best approximate a wide variety of experimental data all three of the subcriteria examined within this category, “neural effort*‘, “muscle stress”, and “muscle dissipation”, should be simultaneously penalized. Once normalized, extensive optimization experience suggests relative weight between these of 1, 5 and 5, respectively. These results lay the foundation for a different conceptual approach for optimization: one stressing optimization as a tool for insight into movement strategies rather than as a technique for trying to “prove” or “disprove” a theory for movement.
REHABILITATIONMECHANISMS OF CHILDRENWITH CEREBRAL PARALYSISBY SIMGLTANERVOUS EFFECT OF ELECTRICCURRENTS ANDMAGNETICFIELD ON CHILD NFNMMOTIVESYSTEM Seregin Yu. V., Candidate of Technical Sciences, Assistant Professor, Rovno, Ukraine, USSR Cur experience of using electric and magnetic stimulation m()ans for relsbilitating children with cerebral paralysis has shown that controlling organism responses by simultaneous effect of electric current (EC) and magnetic field (W) on both links of neuromotive system patient& rehabilitation therapeutic effect is achieved tbrou@ organism proper effortsforced in the process of response dmelopmnt to use all its reserves for forming tictional reflex links. As fomation of &&oh links under neuromotive system central link patholw is impossible witbout preliminary lpobllising brain reserves EC and MF action is directed first at forming organimresponse providing conditions for functional activity of preserved or reversibly changed~neurons and then at their optimal use. For developing and controlling the necessary response W.obtalned analytic
dependences
setting
EC and W parameters
permitting
to exercise
discrete
individually measured effects simultaneously on central an&peripheral links of patient& neuromtive system. Studies show no detrimental affect on patient& organism knd provide adequate control of locomotion formation process with 84% positive results.