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A dynamic 3-D link-segment model applied for calculating joint torques during cleaning work
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Abstracts-International Society of Biomechanics XIV Congress 1993
VIBRATION TECHNIQUE FOR THE STUDY OF SIMULATED FUSIONS OF THE HUMAN LUMBAR SPINE Kevin SC. KWONG’ & John H. EVANS’ ‘Department of Rehabilitation Sciences; *Rehabilitation Engineering Centre, Hong Kong Polytechnic, Hong Kong. Detection and monitoring of fusion in the spine is problematic and currently involves the examination of radiographic data. Acoustic transmission techniques may provide a noninvasive, nonchallenging yet more discriminating means of detecting fusion. Three normal fresh human spines from T12 to the sacrum were cleared of musculature. The specimens were mounted in a horizontal position mimicking that experienced in the body in prone lying. Posterior fusion was simulated by locking the facet joints using self-cutting screws. Interbody fusion was simulated by bolting preformed aluminum strips across the lateral borders of the L3, 4 & 5 vertebral bodies. The force and acceleration transducers were attached to the spinous processesthrough tapered pins. Random vibration force (input) of magnitude lower than 5N in the frequency range of 20 to 2k Hz was applied at the L5 spinous process by an electrodynamic vibrator. The response (output) was detected by accelerometers attached to the other spinous processes.The input and output signals were conditioned and then acquired by a PC-baseddigital system. The transfer function (A(f) which defines the transmissibility of the induced shear waves along the specimen was computed. Data obtained in the intact and fused conditions of the same specimens were compared. Following simulated fusion of the facet joints, the transfer function showed a gross shift from normal towards higher frequencies and a many-fold increase in magnitude, particularly at frequencies higher than 500 Hz. The results suggest preferential transmission of high frequency components through the fused facet joints. Simulated interbody fusion had similar effects on the mechanical behaviour of the specimens. The vibration technique has proved sensitive to identify the increase in structural stiffness of the lumbar spine following fusion.
Pendulum modality to simulate foot-ground impact during locomotor activities M.A. Lafortune and M.J. Lake School of Human Biology, University of Guelph, Guelph, Ontario, Canada Cushioning of impact forces during locomotion is achieved through the physical properties of biological tissues, footwear and surfaces and, through the kinematics of the lower limbs. This study examines the use of a human pendulum to provide a controlled and reproducible method to determine the physical properties of the cushioning system. The Pendulum was suspended 3.5 m. from the ceiling. A force platform was mounted vertically onto a 2 cm thick steel plate bolted to a 14 cm thick concrete wail. The impact characteristics of a 75 kg subject were measured for a series of 10 impacts. He laid supine on the pendulum bed with his impact leg protruding over the edge. The subject was instructed to maintain a constant ankle posture during impact. At rest, the position of the Pendulum was adjusted so that the shod foot of the subject was barely touching the force platform. The force signal was sampled at 2 kHz and low pass filtered at 200 Hz. Pendulum impact velocity (IV) was determined from high speed video (loo0 fps) recordings. The variability of IV, Peak force (PF), loading rate (LR) and contact duration was examined to assess reproducibility of results. For an average IV of 0.904 f 0.02 m/s, PF reached 1077 f 41 N in 41 f 2 ms. An average LR of 29.5 f 3.7 kN/s was observed for a contact duration of 240 * 6 ms. These results attest to the validity and reproducibility of the human pendulum modality. It provides an attractive method to study in vivo cushioning properties of the lower extremities in a controlled manner.
A DYNAMIC 3-D LINK-SEGMENT MODEL APPLIED FOR CALCULATING JOINT TORQUES DURING CLEANING WORK Bjame Laursen, Karen Sogaard and Gisela Sjogaard Department of Physiology, National Institute of Occupational Health, Denmark Lerso Parka116 105, DK-2100 Copenhagen 0, Denmark The aim of this study was to analyze the loads during cleaning work, i.e. mopping of the floor. The forces on each hand were measured with a special developed force transducer handle. Kinematic data was obtained from simultaneous recordings by 3 genlocked video cameras at 50 Hz. Joint centres were digitized, and their three-dimensional coordinates were obtained using Direct Linear Transformation, and velocities and accelerations were calculated by low-pass filtering and differentiation. Net torques were calculated based on a dynamic, three-dimensional link segment model and transformed to body coordinate systems at elbows, glenohumeral joints and L4/L5. The results showed different load patterns for right and left side, elbow torques ranging from -1 to +15 N*m (right) and from -10 to +4 N*m (left). For the glenohumeral joint, torque components varied from -4 to 11 N*m (right) and from -13 to +7 N-m (left). L4/L5 showed a forward bending torque ranging from +23 to +48 Nom and a twisting torque ranging from -35 to +20 Nom. Special attention should be drawn to the latter, which may be one of the most important risk factors for low back disorders associated with work tasks involving high repetitive twisting in the low back.
Abstracts-International Society of Biomechanics XIV Congress 1993
VIBRATION TECHNIQUE FOR THE STUDY OF SIMULATED FUSIONS OF THE HUMAN LUMBAR SPINE Kevin SC. KWONG’ & John H. EVANS’ ‘Department of Rehabilitation Sciences; *Rehabilitation Engineering Centre, Hong Kong Polytechnic, Hong Kong. Detection and monitoring of fusion in the spine is problematic and currently involves the examination of radiographic data. Acoustic transmission techniques may provide a noninvasive, nonchallenging yet more discriminating means of detecting fusion. Three normal fresh human spines from T12 to the sacrum were cleared of musculature. The specimens were mounted in a horizontal position mimicking that experienced in the body in prone lying. Posterior fusion was simulated by locking the facet joints using self-cutting screws. Interbody fusion was simulated by bolting preformed aluminum strips across the lateral borders of the L3, 4 & 5 vertebral bodies. The force and acceleration transducers were attached to the spinous processesthrough tapered pins. Random vibration force (input) of magnitude lower than 5N in the frequency range of 20 to 2k Hz was applied at the L5 spinous process by an electrodynamic vibrator. The response (output) was detected by accelerometers attached to the other spinous processes.The input and output signals were conditioned and then acquired by a PC-baseddigital system. The transfer function (A(f) which defines the transmissibility of the induced shear waves along the specimen was computed. Data obtained in the intact and fused conditions of the same specimens were compared. Following simulated fusion of the facet joints, the transfer function showed a gross shift from normal towards higher frequencies and a many-fold increase in magnitude, particularly at frequencies higher than 500 Hz. The results suggest preferential transmission of high frequency components through the fused facet joints. Simulated interbody fusion had similar effects on the mechanical behaviour of the specimens. The vibration technique has proved sensitive to identify the increase in structural stiffness of the lumbar spine following fusion.
Pendulum modality to simulate foot-ground impact during locomotor activities M.A. Lafortune and M.J. Lake School of Human Biology, University of Guelph, Guelph, Ontario, Canada Cushioning of impact forces during locomotion is achieved through the physical properties of biological tissues, footwear and surfaces and, through the kinematics of the lower limbs. This study examines the use of a human pendulum to provide a controlled and reproducible method to determine the physical properties of the cushioning system. The Pendulum was suspended 3.5 m. from the ceiling. A force platform was mounted vertically onto a 2 cm thick steel plate bolted to a 14 cm thick concrete wail. The impact characteristics of a 75 kg subject were measured for a series of 10 impacts. He laid supine on the pendulum bed with his impact leg protruding over the edge. The subject was instructed to maintain a constant ankle posture during impact. At rest, the position of the Pendulum was adjusted so that the shod foot of the subject was barely touching the force platform. The force signal was sampled at 2 kHz and low pass filtered at 200 Hz. Pendulum impact velocity (IV) was determined from high speed video (loo0 fps) recordings. The variability of IV, Peak force (PF), loading rate (LR) and contact duration was examined to assess reproducibility of results. For an average IV of 0.904 f 0.02 m/s, PF reached 1077 f 41 N in 41 f 2 ms. An average LR of 29.5 f 3.7 kN/s was observed for a contact duration of 240 * 6 ms. These results attest to the validity and reproducibility of the human pendulum modality. It provides an attractive method to study in vivo cushioning properties of the lower extremities in a controlled manner.
A DYNAMIC 3-D LINK-SEGMENT MODEL APPLIED FOR CALCULATING JOINT TORQUES DURING CLEANING WORK Bjame Laursen, Karen Sogaard and Gisela Sjogaard Department of Physiology, National Institute of Occupational Health, Denmark Lerso Parka116 105, DK-2100 Copenhagen 0, Denmark The aim of this study was to analyze the loads during cleaning work, i.e. mopping of the floor. The forces on each hand were measured with a special developed force transducer handle. Kinematic data was obtained from simultaneous recordings by 3 genlocked video cameras at 50 Hz. Joint centres were digitized, and their three-dimensional coordinates were obtained using Direct Linear Transformation, and velocities and accelerations were calculated by low-pass filtering and differentiation. Net torques were calculated based on a dynamic, three-dimensional link segment model and transformed to body coordinate systems at elbows, glenohumeral joints and L4/L5. The results showed different load patterns for right and left side, elbow torques ranging from -1 to +15 N*m (right) and from -10 to +4 N*m (left). For the glenohumeral joint, torque components varied from -4 to 11 N*m (right) and from -13 to +7 N-m (left). L4/L5 showed a forward bending torque ranging from +23 to +48 Nom and a twisting torque ranging from -35 to +20 Nom. Special attention should be drawn to the latter, which may be one of the most important risk factors for low back disorders associated with work tasks involving high repetitive twisting in the low back.