| 1. |
- Andersson, Eva, et al.
(författare)
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EMG activities of the quadratus lumborum and erector spinae muscles during flexion-relaxation and other motor tasks.
- 1996
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Ingår i: Clinical biomechanics (Bristol, Avon). - : Elsevier BV. - 1879-1271 .- 0268-0033. ; 11:7, s. 392-400
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: The aim of this study was to provide new information on the myoelectrical activation of the quadratus lumborum, the deep lateral and the superficial medial lumbar erector spinae, the psoas, and the iliacus muscles in various motor tasks. DESIGN: An intramuscular electromyographic study was performed. BACKGROUND: The contribution of individual deep trunk muscles to the stability of the lumbar spine is relatively unknown in different tasks, including the flexion-relaxation phenomenon. METHODS: Seven healthy subjects participated. Fine-wire electrodes were inserted with a needle guided by ultrasound. RESULTS: The highest activity observed for quadratus lumborum and deep lateral erector spinae occurred in ipsilateral trunk flexion in a side-lying position and for superficial medial erector spinae during bilateral leg lift in a prone position. Quadratus lumborum and deep lateral erector spinae were activated when the flexion-relaxation phenomenon was present for superficial medial erector spinae, i.e. when its activity ceased in the latter part of full forward flexion of the trunk, held relaxed and kyphotic. CONCLUSIONS: In general, the activation of the investigated muscles showed a high degree of task specificity, where activation of a certain muscle was not always predictable from its anatomical arrangement and mechanical advantage.
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| 2. |
- Farewik, Lanie, 1973-
(författare)
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Mild diabetic neuropathy affects ankle motor function
- 2001
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Ingår i: Clinical Biomechanics. - 0268-0033 .- 1879-1271. ; 16:6, s. 522-528
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Tidskriftsartikel (refereegranskat)abstract
- Objective. To evaluate the effect of age and diabetic neuropathy on ankle motor function in the frontal plane in terms of rate of torque development and capability for balance recovery.Design. Case control study. Six older women with diabetic neuropathy compared to six women without neuropathy, matched for age and presence of diabetes mellitus; and nine healthy young women.Background. Neuropathy causes a distal impairment in lower extremity sensory function which increases fall risk. Impairments in ankle inversion/eversion proprioceptive thresholds have been identified, but the effect of neuropathy on ankle motor strength in the frontal plane is unknown.Methods. Subjects' abilities to recover from a lateral lean (with center of gravity offset as percentage of foot width) while standing on one foot, and to rapidly generate inversion torque about the ankle, were quantified.Results. All nine of the young, but only one of six older, control subjects recovered from a 10% lean (P=0.0052). Three of six older controls, but no neuropathy subject, recovered from a 5% lean (P=0.083). Neuropathy subjects demonstrated half the ankle rate of torque development [78.2 (50.8) N m/s; P=0.016] of the young and older controls [162.0 (54.6) and 152.7 (22.2) N m/s, respectively].Conclusions. Diabetic neuropathy leads to a decrease in rapidly available ankle strength which impairs balance recovery among older women. Younger women demonstrate similar ankle strength but superior balance recovery compared to older women without neuropathy.RelevanceOlder women with diabetic neuropathy and normal ankle strength, as judged by clinical muscle testing, demonstrate a sub-clinical impairment in ankle motor function suggesting a target for intervention.
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| 3. |
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| 4. |
- Ramsey, D. K., et al.
(författare)
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Assessment of functional knee bracing : an in vivo three-dimensional kinematic analysis of the anterior cruciate deficient knee
- 2001
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Ingår i: Clinical Biomechanics. - Oxon, United Kingdom : Elsevier. - 0268-0033 .- 1879-1271. ; 16:1, s. 61-70
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Tidskriftsartikel (refereegranskat)abstract
- Objective: To describe three-dimensional tibial and femoral movements in vivo and examine the effect of a brace on knee kinematics during moderate to intense activity.Design: Skeletal kinematics of anterior cruciate ligament deficient knees was measured with and without braces during moderate to intense activity.Background: Invasive markers implanted into the tibia and femur are the most accurate means to directly measure skeletal motion and may provide a more sensitive measure of the differences between brace conditions.Methods: Steinmann traction pins were implanted into the femur and tibia of four subjects having a partial or complete anterior cruciate ligament rupture. Non-braced and braced conditions were randomly assigned and subjects jumped for maximal horizontal distance to sufficiently stress the anterior cruciate ligament.Results: Intra-subject peak vertical force and posterior shear force were generally consistent between conditions. Intra-subject kinematics was repeatable but linear displacements between brace conditions were small. Differences in angular and linear skeletal motion were observed across subjects. Bracing the anterior cruciate ligament deficient knee resulted in only minor kinematic changes in tibiofemoral joint motion.Conclusion: In this study, no consistent reductions in anterior tibial translations were observed as a function of the knee brace tested. Relevance. Investigations have reported that knee braces fail when high loads are encountered or when load is applied in an unpredictable manner. Questions remain regarding tibiofemoral joint motion, in particular linear displacements. The pin technique is a means for direct skeletal measurement and may provide a more sensitive measure of the differences between brace conditions.
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| 5. |
- Ramsey, D. K., et al.
(författare)
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Biomechanics of the knee : methodological considerations in the in vivo kinematic analysis of the tibiofemoral and patellofemoral joint
- 1999
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Ingår i: Clinical Biomechanics. - Oxford, United Kingdom : Elsevier. - 0268-0033 .- 1879-1271. ; 14:9, s. 595-611
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Forskningsöversikt (refereegranskat)abstract
- The purpose of this review article is twofold: to report on the use of intracortical pins to measure three-dimensional tibiofemoral and patellofemoral joint kinematics and highlight methodological concerns associated with this procedure. Tibiofemoral and patellofemoral kinematics has been extensively investigated using reflective markers attached to the surrounding soft tissue of the calf and thigh. However, surface markers may not adequately represent true anatomical locations and skin movement artefacts present the most critical source of measurement error. Consequently, knowledge about skeletal tibiofemoral kinematics is limited, in particular abduction-adduction and internal-external rotations. Considerable questions remain regarding what constitutes normal motion of the knee. A way to avoid the problem of surface markers is use invasive markers to directly measure skeletal motion. To date, many co-ordinate systems have been used to describe three-dimensional skeletal kinematics of the lower limb in vivo. They include helical axes, finite helical axes, instantaneous helical axes, and the joint co-ordinate system based on local anatomic landmarks. Although each method accurately describes the relative motion in 6 d. of f., the differences in how the motion is partitioned may account for the differences across investigations. Additionally, the problem of defining the anatomical co-ordinate system makes comparisons across subjects and studies difficult since subtle differences may be caused by small deviations in the anatomical reference alignment. Cross talk is also a primarily a concern. For joints that articulate principally about one axis, the primary flexion/extension that is registered will be cross-talked into ab/adduction and internal/external rotations.
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| 6. |
- Ramsey, Dan K., et al.
(författare)
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Electromyographic and biomechanic analysis of anterior cruciate ligament deficiency and functional knee bracing
- 2003
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Ingår i: Clinical Biomechanics. - Oxon, United Kingdom : Elsevier. - 0268-0033 .- 1879-1271. ; 18:1, s. 28-34
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Tidskriftsartikel (refereegranskat)abstract
- Objective: Examine the neuromuscular response to functional knee bracing relative to anterior tibial translations in vivo.Design: During randomised brace conditions, electromyographic data with simultaneous skeletal tibiofemoral kinematics were recorded from four anterior cruciate ligament deficient subjects to investigate the effect of the DonJoy Legend functional brace during activity.Background: Knee braces do not increase knee stability but may influence afferent inputs from proprioception and therefore one might expect changes in muscle firing patterns, amplitude and timing.Methods: Hoffman bone pins affixed with markers were implanted into the tibia and femur for kinematic measurement. The EMG data from the rectus femoris, semitendinosus, biceps femoris, and lateral head of the gastrocnemius were integrated for each subject in three separate time periods: 250 ms preceding footstrike and two consecutive 125 ms time intervals following footstrike.Results: With brace, semitendinosus activity significantly decreased 17% prior to footstrike whereas bicep femoris significantly decreased 44% during A2, (P<0.05). Rectus femoris activity significantly increased 21% in A2 (P<0.05). No consistent reductions in anterior translations were evident.Conclusion: Our preliminary findings, based on a limited number of subjects, indicate joint stability may result from proprioceptive feedback rather than the mechanical stabilising effect of the brace. Despite a significant increase in rectus femoris activity upon landing, only one subject demonstrated an increase in anterior tibial drawer.Relevance: Studies have shown functional braces do not mechanically stabilise the anterior cruciate ligament deficient knee. Perhaps bracing alters proprioceptive feedback. It has been shown that bracing the anterior cruciate ligament deficient knee may affect hamstring and quadriceps activity. Our findings stresses the importance of functional knee bracing combined with proprioceptive and muscular coordination training in order to increase joint stability.
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| 7. |
- Wretenberg, Per, 1963-, et al.
(författare)
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Effect of armrests and different ways of using them on hip and knee load during rising
- 1993
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Ingår i: Clinical Biomechanics. - Oxon, United Kingdom : Butterworth-Heinemann. - 0268-0033 .- 1879-1271. ; 8:2, s. 95-101
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Tidskriftsartikel (refereegranskat)abstract
- The loading moments of force about the hip and knee joints of ten healthy male subjects were calculated using recorded forces from a force plate and static contribution from body segments. The subjects rose from a chair while using armrests in ten different ways, and, as a reference, without arm aid. The influence of different armrest heights, hand placements and arm forces was studied. Horizontal and vertical forces on the armrests were measured. Irrespective of armrest height and hand placement, the use of armrests significantly reduced the hip and knee moments compared to rising without arm aid (P < 0.001). However, there were no statistically significant differences between different armrest heights or hand placements. High arm force reduced both hip and knee moments. The greatest reduction occurred for high armrests and high arm force, which reduced the mean peak hip moment from 39 to 17 N m and the knee moment from 83 to 28 N m. Calculation of patellofemoral compressive force and the force on the femoral head due to extensor muscle activity demonstrated that local hip and knee forces were reduced when armrests were used. Horizontal forces applied to the armrests were small. Subjectively 'doubled' arm force resulted in nearly double force on the armrests.
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| 8. |
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| 9. |
- Wretenberg, Per, 1963-, et al.
(författare)
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Passive knee muscle moment arms measured in vivo with MRI
- 1996
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Ingår i: Clinical Biomechanics. - Oxon, United Kingdom : Butterworth-Heinemann. - 0268-0033 .- 1879-1271. ; 11:8, s. 439-446
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Tidskriftsartikel (refereegranskat)abstract
- Objective: To determine moment arm lengths from seven knee muscles and the patellar tendon. The knee muscles were the biceps femoris, semitendinosus, semimembranosus, gracilis, sartorius, and the lateral and medial gastrocnemius muscles.Design: The moment arms were calculated based on MRI measurements.Background: Moment arm lengths of different muscles with respect to the joint centre of rotation (CR) or the centre of the contact point between joint surfaces are necessary basic data for biomechanical models predicting joint load.Methods: Ten male and seven female subjects participated. Using a 1.5 Tesla magnetic resonance imaging system, 3-dimensional coordinates of relevant points were recorded from a 3-D volume reconstruction of the right knee at knee flexion angles of 0, 30 and 60 degrees. Muscular moment arms were calculated in both the sagittal and frontal planes. The recordings were all made during passive mode, which means that no muscular contraction was performed.Results: All muscles except the lateral gastrocnemius showed statistically significant differences (P<0.05) of moment arm lengths between gender in the frontal plane. All muscles except biceps femoris and sartorius showed significant differences (P<0.05) of moment arm lengths between gender in the sagittal plane. Most muscles also showed a linear or quadratic trend of changing moment arms with varying knee angle. CONCLUSIONS: Our results indicate that for most biomechanical analyses involving knee muscles, gender- and angle-specific moment arms should be used.
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| 10. |
- Wretenberg, Per, 1963-, et al.
(författare)
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Tibiofemoral contact points relative to flexion angle measured with MRI
- 2002
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Ingår i: Clinical Biomechanics. - Oxon, United Kingdom : Elsevier. - 0268-0033 .- 1879-1271. ; 17:6, s. 477-485
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Tidskriftsartikel (refereegranskat)abstract
- Objective: To determine whether knee flexion influenced bony contact movements during flexion.Design: Accurate three-dimensional (3D) measurements of tibiofemoral bony contact points in vivo was performed using magnetic resonance imaging technology at 0 degrees, 30 degrees and 60 degrees of flexion.Background: Magnetic resonance imaging is an accurate non-invasive tool for visualizing muscles, tendons, and bone, and provides precise 3D co-ordinates.Methods: Magnetic resonance imaging recordings were made from the right knee of 16 subjects with no history of knee dysfunction at 0 degrees, 30 degrees and 60 degrees of flexion. Joint contact movements were reported as changes of the contact point's position on the medial and lateral tibial condyle with respect to a fixed reference point for each flexion angle.Results: The dominant motion of the centroid of the contact area was posterior with a concomitant inferior and lateral displacement when flexing from 0-30 degrees. Increased flexion to 60 degrees the contact points moved slightly anterior, superior and continued laterally. Comparing movements between the medial and lateral compartments, larger displacement magnitudes were observed laterally. Additionally, tibial rotations of 3-5 degrees were noted relative to the femur.Conclusion: Based on magnetic resonance imaging co-ordinates and the rotated anatomical reference frame, the geometric equations to derive the contact point between the tibiofemoral articulating surfaces is a viable means to investigate tibiofemoral bony contact movement.Reslevance: Contact areas and pressure distributions have been reported using cadaveric specimens but interpretation of the results is limited. Other investigations have been restricted to sagittal plane movement. Using kinematic magnetic resonance imaging, accurate non-invasive 3D recordings of the normal knee at increments of flexion are possible. The normative baseline date can be compared against that of the pathological knee, such as cruciate ligament injury or the status of post-operative meniscectomy in order to examine skeletal joint motion and stability.
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