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The pathogeny of ankle sprain: Evaluation of a hypothesis
Abstracts-International
Society of Biomechanics
1089
XII Congress 1989
THE PATHOGENYOF ANKLE SPRAIN: EVALUATION OF A HYPOTHFSIS J.L. Thonnard, P. Willems, L. Plaghki and J. De Nayer Unit.6 de RBadaptation, Universitd Catholique de Louvain, 53, 1200 Bruxelles, Belgium. UCL 5375, av. Mounier, reflexes are assumed to prevent ankle Ligamento-muscular protective sprain, This hypothesis can be tested by determining: 11 the reflex latenties of the foot evertors in response to an inversion movement and 21 the time to produce an ankle sprain during a varus movement. The latencies are measured on 7 healthy subjects. The second delay is obtained by simulating one foot lands on a (* 30 cm) where the landing of a vertical jump pavement kerb. To implement the computer simulation, we investigated, in 3 the relationship between in vivo torque and angle both healthy volunteers, and dynamic conditions, with the evertor muscles either relaxed in static (passive torque) or during maximal voluntary contraction (active torque). The results show that during this ankle sprain situation, (1) the peri-articular passive structures are unable to absorb the mechanical (2) the time necessary to reach the energy of the inversion sprain, and angle of capsular-ligamentous rupture is inferior to the reflex latencies simulations with variations of the we observe. We have performed several model parameters and it seems that in this particular situation, an ankle sprain cannot be avoided.
LUMBAR SPINE AND PSOAS MUSCLE GEOMETRY REVISITED WITH MAGNETIC RESONANCE IMAGING Alf Thorstensson, Eva Andersson, and Andrew G. Cresswell
Department of Physiology III, Karolinska Institute, and University College of Physical Education (GIH), LidingBvggen 1, S-114 33 Stockholm, Sweden. Magnetic resonance imaging (1.0 tesla magnet) was used to describe the geometry of the spine and the psoas muscle at different lumbar levels. Four healthy young males participated. Each subject was placed supine in three different positions: straight, hips flexed, or with maximal lumbar lordosis. Sagittal, frontal, and transverse sections (lcm thick) at each intervertebral junction were obtained as well as oblique sections along the psoas muscle. The cross-sectional area of the psoas muscle increased progressively from Ll (3.8 cm’) to L5 level (17.0 cm2). In the upper lumbar spine psoas had an extensor moment arm (Ll-L2: 12 mm) which gradually changed to a flexor at LA-L5 level, and was largest at L5Sl (14 mm). The moment arm for lateral flexion showed a continuous increase from Ll to Sl (30 to 54 mm). Hip flexion (35-40 deg.) did not significantly influence the geometry of the spine or psoas. The hyper-lordosis occurred both in the upper (increased backward tilt of vertebral bodies) and lower lumbar spine (sacral forward tilt increased from 30 to 52 deg.), and could thus be achieved by a contraction of the psoas muscle. The present study has demonstrated the feasibility of magnetic resonance imaging in obtaining comprehensive information in viva about the anatomical detail, which in turn forms a necessary basis for functional studies and biomechanical modelling. Here, it forms a starting point for the investigation of the involvement of the psoas muscle in hyper-lordosis of the lumbar spine and its possible relation to low back problems.
DETERMINING MUSCLE FORCE INVERSE DYNAMICS METHOD J.G.M. Thunnissen, Biomechanics Group, P.O. Box 217, 7500 In the analyses using a prosthesis,
AND
ENERGY
IN
THE
L.EG DURING
H.J. Grootenboer, H.F.J.M. Koopman, Faculty of Mechanical Engineering, AE Enschede, The Netherlands. of
walking important
HUNAN
WALKING
H.J. de University
USING
THE
Jongh of
Twente,
patterns, especially the patterns of leg-amputees questions are: why are these patterns different from the pattern of non-amputees, what are the consequences and what is the influence of prosthesis construction, fitting and alignment on gait. Research is needed in not only the differences in body-movement, joint moments and forces, but also in the muscle activities and forces. A good prediction about metabolic energy consumption and endurance time can be derived for the muscle activities and forces. The use of optimizing techniques gives muscle force histories that can be compared to electromyographic data. By using a fourier series description of the muscle activity, influences of previous time steps on momentary muscle forces and biarticularity of some muscles were included. However the prediction of the optimal process highly depends on the numerical stability of the contraction and excitation equations of the muscle model. A complete three-dimensional calculation is hard to solve, but the predictions of the total energy and muscle activity, from the flexion/extension muscles, are good.
Society of Biomechanics
1089
XII Congress 1989
THE PATHOGENYOF ANKLE SPRAIN: EVALUATION OF A HYPOTHFSIS J.L. Thonnard, P. Willems, L. Plaghki and J. De Nayer Unit.6 de RBadaptation, Universitd Catholique de Louvain, 53, 1200 Bruxelles, Belgium. UCL 5375, av. Mounier, reflexes are assumed to prevent ankle Ligamento-muscular protective sprain, This hypothesis can be tested by determining: 11 the reflex latenties of the foot evertors in response to an inversion movement and 21 the time to produce an ankle sprain during a varus movement. The latencies are measured on 7 healthy subjects. The second delay is obtained by simulating one foot lands on a (* 30 cm) where the landing of a vertical jump pavement kerb. To implement the computer simulation, we investigated, in 3 the relationship between in vivo torque and angle both healthy volunteers, and dynamic conditions, with the evertor muscles either relaxed in static (passive torque) or during maximal voluntary contraction (active torque). The results show that during this ankle sprain situation, (1) the peri-articular passive structures are unable to absorb the mechanical (2) the time necessary to reach the energy of the inversion sprain, and angle of capsular-ligamentous rupture is inferior to the reflex latencies simulations with variations of the we observe. We have performed several model parameters and it seems that in this particular situation, an ankle sprain cannot be avoided.
LUMBAR SPINE AND PSOAS MUSCLE GEOMETRY REVISITED WITH MAGNETIC RESONANCE IMAGING Alf Thorstensson, Eva Andersson, and Andrew G. Cresswell
Department of Physiology III, Karolinska Institute, and University College of Physical Education (GIH), LidingBvggen 1, S-114 33 Stockholm, Sweden. Magnetic resonance imaging (1.0 tesla magnet) was used to describe the geometry of the spine and the psoas muscle at different lumbar levels. Four healthy young males participated. Each subject was placed supine in three different positions: straight, hips flexed, or with maximal lumbar lordosis. Sagittal, frontal, and transverse sections (lcm thick) at each intervertebral junction were obtained as well as oblique sections along the psoas muscle. The cross-sectional area of the psoas muscle increased progressively from Ll (3.8 cm’) to L5 level (17.0 cm2). In the upper lumbar spine psoas had an extensor moment arm (Ll-L2: 12 mm) which gradually changed to a flexor at LA-L5 level, and was largest at L5Sl (14 mm). The moment arm for lateral flexion showed a continuous increase from Ll to Sl (30 to 54 mm). Hip flexion (35-40 deg.) did not significantly influence the geometry of the spine or psoas. The hyper-lordosis occurred both in the upper (increased backward tilt of vertebral bodies) and lower lumbar spine (sacral forward tilt increased from 30 to 52 deg.), and could thus be achieved by a contraction of the psoas muscle. The present study has demonstrated the feasibility of magnetic resonance imaging in obtaining comprehensive information in viva about the anatomical detail, which in turn forms a necessary basis for functional studies and biomechanical modelling. Here, it forms a starting point for the investigation of the involvement of the psoas muscle in hyper-lordosis of the lumbar spine and its possible relation to low back problems.
DETERMINING MUSCLE FORCE INVERSE DYNAMICS METHOD J.G.M. Thunnissen, Biomechanics Group, P.O. Box 217, 7500 In the analyses using a prosthesis,
AND
ENERGY
IN
THE
L.EG DURING
H.J. Grootenboer, H.F.J.M. Koopman, Faculty of Mechanical Engineering, AE Enschede, The Netherlands. of
walking important
HUNAN
WALKING
H.J. de University
USING
THE
Jongh of
Twente,
patterns, especially the patterns of leg-amputees questions are: why are these patterns different from the pattern of non-amputees, what are the consequences and what is the influence of prosthesis construction, fitting and alignment on gait. Research is needed in not only the differences in body-movement, joint moments and forces, but also in the muscle activities and forces. A good prediction about metabolic energy consumption and endurance time can be derived for the muscle activities and forces. The use of optimizing techniques gives muscle force histories that can be compared to electromyographic data. By using a fourier series description of the muscle activity, influences of previous time steps on momentary muscle forces and biarticularity of some muscles were included. However the prediction of the optimal process highly depends on the numerical stability of the contraction and excitation equations of the muscle model. A complete three-dimensional calculation is hard to solve, but the predictions of the total energy and muscle activity, from the flexion/extension muscles, are good.