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  • 1
    ISSN: 1432-5195
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Résumé Cet article décrit l'utilisation du transducteur de tension par effet Hall (TTEH) dans une nouvelle technique arthroscopique pour étudier le ligament croisé antérieur (LCA) normal in vivo. Les participants à l'étude étaient des patients volontaires avec LCA normal, soumis à une arthroscopie à visée diagnostique ou à une intervention sur un ménisque, sous anesthésie locale. Le TTEH fut implanté dans la bande médiane antérieure (BMA) du LCA. La translation antérieure du tibia, le fémur étant fixé et le genou fléchi à 30° (test de Lachman), donne des chiffres de tension sensiblement plus élevés par rapport à ceux obtenus en flexion à 90° (épreuve de tiroir antérieur). Lors de la contraction isométrique du quadriceps, une augmentation significative de la tension de la BMA a été notée, le genou fléchi à 30°, alors qu'aucune modification n'était mesurable à 90°. Lors des contractions du quadriceps, les chiffres de tension de la BMA, le genou fléchi à 30° étaient notablement supérieurs à ceux enregistrés à 90°. Dans le secteur de mobilité active, la BMA était sous tension entre 10° et 48° et ne l'était pas de 48° à 110°. Durant la mobilisation passive la BMA restait détendue jusqu'à ce que l'articulation soit mise en extension complète. On a trouvé des différences significatives entre les tensions mesurées lors des mobilisations actives et passives aux angles de flexion de 10°, 20°, 30° et 40°, alors qu'il n'y en avait pas de 50° à 110°. Ces résultats confirment les études antérieures selon lesquelles le test de Lachman est une technique d'examen plus sensible que la classique recherche du tiroir antérieur pour évaluer la BMA. Ces résultats laissent à penser que l'activité isométrique du quadriceps, le genou fléchi à 90°, peut être prescrite pour la réeducation, immédiatement après reconstruction du LCA. Ces données indiquent également que la mobilisation active (entre 50° et 110°) et la mobilisation passive peuvent être effectuées avec des risques mineurs après reconstruction. Les données concernant la mobilité passive peuvent aussi fournir des repères valables pour la reconstruction du LLA.
    Notes: Summary This article describes the use of the Hall Effect strain transducer (HEST) in a new arthroscopic technique to study the normal anterior cruciate ligament (ACL) in-vivo. Study participants were patient volunteers with normal ACLs undergoing diagnostic arthroscopic or meniscal surgery under local anaesthesia. The HEST was implanted into the Anterior Medial Band (AMB) of the ACL. Anterior shear loading of the tibia in relation to the fixed femur at 30° of knee flexion (Lachman test), produced significantly greater strain values in comparison to anterior shear loading at 90° (Anterior Drawer test). During isometric quadriceps contraction a significant increase in AMB strain was measured with the knee flexed to 30°, while no significant change was measured at 90°. For quadriceps contraction there were significantly higher values of AMB strain measured at 30° of knee flexion in comparison to that observed at 90°. For active range of motion (AROM) the AMB was strained between 10° and 48°, and unstrained between 48° and 110°. During passive range of motion (PROM) the AMB remained unstrained until the joint was brought into extension. There were significant differences in strain values found between AROM and PROM at the flexion angles 10°, 20°, 30° and 40°, while between 50° and 110° there were no significant differences. These results confirm previous studies that the Lachman test is a superior technique in comparison to the classic anterior drawer test for evaluating the AMB. They suggest that isometric quadriceps activity at 90° of knee flexion can be prescribed for rehabilitation immediately after ACL reconstruction. These data indicate that AROM (between the limits of 50° and 110°) and PROM may also be performed with minimal risk of strain to a reconstructive replacement. The PROM data may also serve as an important standard for the reconstruction of the ACL.
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  • 2
    ISSN: 1432-0932
    Keywords: Low back pain ; von Willebrand factor antigen ; Vibration ; Vascular damage ; Endothelium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The von Willebrand factor (vWf) is a complex protein whose release is a marker for endothelial damage; serum levels of its antigen (vWFAg) can be used as a marker for such changes. We measured the levels of back discomfort and vWFAg in 11 subjects following 25-min periods of (1) lying down, (2) sitting upright, (3) vibrating whilst sitting and (4) sitting upright. Back discomfort appeared and vWf levels were significantly increased following sitting upright, compared with lying flat, and increased further following vibration. They fell thereafter with a period of sitting still upright. These results demonstrate that vibration has a significant effect in increasing back discomfort and the serum levels of vWFAg, and it is possible that vibration may induce vascular damage within the spine.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-0932
    Keywords: Muscle response ; Sudden load ; Posture ; Low back pain ; Rehabilitation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Unexpected loads, which often occur in the working environment, can lead to high forces in the spine and, thus, may be a cause of low back injury. This paper discusses the effect of “sudden load” on the erector spine reaction and amplitude. Muscle responses were mediated by several factors, including fatigue, posture, expectation and rehabilitation, in chronic low back pain patients. The subjects were fatigued by holding a 20% maximum voluntary contraction for 1 min. A functional restoration program was tested for its efficacy in reducing reaction time and EMG amplitude in chronic low back pain patients. Reaction time was longer and EMG amplitude lower in patients than in their matched controls. EMG reaction time and magnitude decreased in patients after a 2-week rehabilitation program, including specific training of coordination and posture control. The results of the modelling showed higher spinal compressive load and lower shear forces when the load was expected than when the load was unexpected. The effect of sudden loads can be exacerbated if a worker is not standing on a flat surface or is fatigued. Chronic low back pain patients have less ability to protect themselves from sudden loads, but they can be trained to improve their response by means of an appropriate rehabilitation program.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1432-0932
    Keywords: Key words Whiplash ; Muscle ; activity ; Electromyography ; Acceleration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Whiplash motion of the neck is characterized by having an extension-flexion motion of the neck. It has been previously assumed that muscles do not play a role in the injury. Eight healthy males were seated in a car seat mounted on a sled. The sled was accelerated by a spring mechanism. Muscle electromyographic (EMG) activity was measured by wire electrodes in semispinalis capitis, splenius capitis, and levator scapulae. Surface EMG activity was measured over trapezius and sternocleidomastoideus. Wavelet analysis was used to establish the onset of muscle activity with respect to sled movement. Shorter reaction times were found to be as low as 13.2 ms from head acceleration and 65.6 ms from sled acceleration. Thus the muscles could influence the injury pattern. It is of interest that clinical symptoms are often attributed to muscle tendon injuries.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1573-9686
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Technology
    Notes: Abstract The paper examines the behavior of anisotropic compact bone in tension at a range of strain rates. Specimens of fresh bovine bone were loaded at strain rates between. 001 and 200 sec−1. This bone was shown to exhibit considerable plasticity throughout the range, except when tested in a direction normal to the long axis. The modulus of elasticity, breaking stress and breaking strain were found to vary with strain rate. There is a maximum energy absorbtion capability at a strain rate of .1 sec−1.
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  • 6
    ISSN: 0736-0266
    Keywords: Myoelectric activity ; Trunk musculature ; Torque, axial ; Life and Medical Sciences
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The myoelectric activity of selected trunk muscles at the L3 level was studied during the development of a controlled isometric axial torque. Muscle activity was recorded with surface electrodes bilaterally over the erector spinae muscles, the rectus abdominus, the obliques externus, and the obliques internus. Subjects applied graded isometric axial torque efforts with the addition of a Valsalva. The largest myoelectric activities were recorded over the obliques externus and internus. The side of the muscle developing the torque did show the greatest myoelectric activity, but considerable antagonistic activity was also present. Neither the rectus abdominus nor the internal oblique muscles showed any difference from side to side. The calculated forces in the rectus abdominus and the erectores spinae were high, suggesting that a considerable amount of the muscle contraction was used to control the posture. A Valsalva did not decrease myoelectric activity, but did increase the torque developed.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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