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| 2. |
- Frohm, Anna, et al.
(författare)
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Patellar tendon load in different types of eccentric squats
- 2007
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Ingår i: Clinical Biomechanics. - : Elsevier BV. - 0268-0033 .- 1879-1271. ; 22:6, s. 704-711
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Tidskriftsartikel (refereegranskat)abstract
- Background. Differences in mechanical loading of the patellar tendon have been suggested as a reason for varying effects in rehabilitation of patellar tendinopathy using different eccentric squat exercises and devices. The aim was to characterize the magnitude and pattern of mechanical load at the knee and on the patellar tendon during four types of eccentric squat. Methods. Subjects performed squats with a submaximal free weight and with maximal effort in a device for eccentric overloading (Bromsman), on a decline board and horizontal surface. Kinematics was recorded with a motion-capture system, reaction forces with force plates, and electromyography from three leg muscles with surface electrodes. Inverse dynamics was used to calculate knee joint kinetics. Findings. Eccentric work, mean and peak patellar tendon force, and angle at peak force were greater (25-30%) for squats on decline board compared to horizontal surface with free weight, but not in Bromsman. Higher knee load forces (60-80%), but not work, were observed with Bromsman than free weight. Angular excursions at the knee and ankle were larger with decline board, particularly with free weight, and smaller in Bromsman than with free weight. Mean electromyography was greater on a decline board for gastrocnemius (13%) and vastus medialis (6%) with free weight, but in Bromsman only for gastrocnemius (7%). Interpretation. The results demonstrated clear differences in the biomechanical loading on the knee during different squat exercises. Quantification of such differences provides information that could be used to explain differences in rehabilitation effects as well as in designing more optimal rehabilitation exercises for patellar tendinopathy.
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| 3. |
- Grenholm, Anton, et al.
(författare)
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Kinematic analyses during stair descent in young women with patellofemoral pain
- 2009
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Ingår i: Clinical Biomechanics. - : Elsevier BV. - 0268-0033 .- 1879-1271. ; 24:1, s. 88-94
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Compensatory movement strategies may develop in response to pain to avoid stress on the affected area. Patellofemoral pain is characterised by intermittent periods of pain and the present study addresses whether long-term pain leads to compensatory movement strategies that remain even when the pain is absent. METHOD: Lower extremity kinematics in three dimensions was studied in stair descent in 17 women with patellofemoral and in 17 matched controls. A two-dimensional geometric model was constructed to normalise kinematic data for subjects with varying anthropometrics when negotiating stairs of fixed proportions. RESULTS: There were minor differences in movement patterns between groups. Knee joint angular velocity in the stance leg at foot contact was lower and the movement trajectory tended to be jerkier in the patellofemoral group. The two-dimensional model showed greater plantar flexion in the swing leg in preparation for foot placement in the patellofemoral group. INTERPRETATION: The results indicate that an altered stair descent strategy in the patellofemoral group may remain also in the absence of pain. The biomechanical interpretation presumes that the strategy is aimed to reduce knee joint loading by less knee joint moment and lower impact force.
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| 5. |
- Kvist, Joanna, 1967-, et al.
(författare)
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Changes in knee motion pattern after anterior cruciate ligament injury - A case report
- 2007
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Ingår i: Clinical Biomechanics. - : Pergamon Press. - 0268-0033 .- 1879-1271. ; 22:5, s. 551-556
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Tidskriftsartikel (refereegranskat)abstract
- Background: After an anterior cruciate ligament injury, the contra-lateral non-injured leg has been found to adapt towards the injured leg. Accordingly, in order to study changes in knee motion pattern after an anterior cruciate ligament injury, the ideal is to compare the same leg prior to and after the injury. However, this is very seldom possible. The purpose of the present study was to describe changes in static and dynamic sagittal tibial translation, electromyographic activity and muscle torque relevant to an anterior cruciate ligament tear in one patient evaluated both before and after the injury.Methods: A male soccer player was examined 11 weeks before and eight weeks after an anterior cruciate ligament injury. Sagittal tibial translation was measured with the CA-4000 electrogoniometer, statically during Lachman's test, and dynamically during isokinetic muscle testing, one-legged squat and level walking. The electromyographic activity of mm. quadriceps and hamstrings, was registered simultaneously during the one-legged squat test.Findings: Static tibial translation was increased by ∼2 mm, while dynamic tibial translation was decreased by 0.4 mm at isokinetic testing, 0.9 mm at one-legged squat and 2.4 mm during level walking compared to before the injury. Muscle torque decreased 30% and 35% for the quadriceps and the hamstrings muscle, respectively. The electromyographic activity revealed similar activation levels in quadriceps and a doubled level of activation in hamstring compared to before the injury.Interpretation: In spite of an increase in static tibial translation eight weeks after an anterior cruciate ligament injury, the tibial translation decreased during activity, thus indicating that the patient could stiffen the knee in order to protect it against increased shear forces.
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| 6. |
- Newell, Theresa M., et al.
(författare)
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Comparison of instantaneous and cumulative loads on the low back and neck in orthodontists
- 2005
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Ingår i: Clinical Biomechanics. - : Elsevier BV. - 0268-0033 .- 1879-1271. ; 10:2, s. 130-7
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Musculoskeletal disorders of back and neck among orthodontists are prevalent. Due to low instantaneous load they have not been investigated. The present study aimed to quantify and compare instantaneous and cumulative loads on low back and neck in orthodontists. METHODS: The sample included nine graduate orthodontic students from the University of Alberta and one practicing orthodontist to validate the generalization from student to professional group. The subjects were videotaped performing regular duties and the recorded postures were printed for biomechanical analysis of compression and shear loads and exposure time. Instantaneous loads were calculated using a biomechanical model developed specifically for this study and cumulative loads were calculated from the resultant loads. FINDINGS: The average instantaneous low back compression loads for men and women were found to be 1383 N and 936 N respectively. The average daily cumulative load on the other hand were found to be 16.2 MNs and 9.9 MNs for males and females respectively. INTERPRETATION: The study demonstrates that smaller loads cannot be ignored due to their magnitude if their duration is long because the time dependent properties of the tissues become modulating factor. Thus the measurement of instantaneous loads on tasks in orthodontists is not indicative of the amount of cumulative stress experienced by them.
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| 7. |
- Baranto, Adad, 1966, et al.
(författare)
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Vertebral fractures and separations of endplates after traumatic loading of adolescent porcine spines with experimentally-induced disc degeneration
- 2005
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Ingår i: Clin Biomech (Bristol, Avon). - : Elsevier BV. - 0268-0033. ; 20:10, s. 1046-54
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Abnormalities of the intervertebral discs have been found in a high frequency among young elite athletes. Several studies have also reported that the adolescent spine, especially the vertebral growth zones, is vulnerable to trauma. However, there is incomplete knowledge regarding the injury mechanism of the growing spine. In this study, the injury patterns of the adolescent porcine spine with disc degeneration were examined. METHODS: Twenty-four male pigs were used. A degenerative disc was created by drilling a hole through the cranial endplate of a lumbar vertebra into the disc. Two months later the animals were sacrificed and the degenerative functional spinal units (segments) were harvested. The segments were divided into three groups and exposed to axial compression, flexion compression or extension compression to failure. The load and angle at failure were measured for each group. The segments were examined with magnetic resonance imaging and plain radiography before and after the loading and finally examined macroscopically and histologically. FINDINGS: The degenerated segments required considerably more compressive load to failure than non-degenerated segments. Creating a flexion injury required significantly more load than an extension injury. Fractures and/or separations of the endplates from the vertebral bodies were seen at the margins of the endplates and in the growth zone. Only severe separations and fractures could be seen on plain radiography and magnetic resonance imaging. INTERPRETATION: The weakest part of the adolescent porcine lumbar spine with experimentally-induced degeneration, when loaded in axial compression, flexion compression or extension compression, was the growth zone, and, to a lesser extent, the endplate. Degenerated discs seem to withstand higher mechanical loads than non-degenerated discs, probably due to altered stress distribution.
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| 9. |
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| 10. |
- Lee, W. C., et al.
(författare)
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Kinetics of transfemoral amputees with osseointegrated fixation performing common activities of daily living
- 2007
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Ingår i: Clin Biomech (Bristol, Avon). - : Elsevier BV. - 0268-0033. ; 22:6, s. 665-73
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Direct anchorage of a lower-limb prosthesis to the bone through an implanted fixation (osseointegration) has been suggested as an excellent alternative for amputees experiencing complications from use of a conventional socket-type prosthesis. However, an attempt needs to be made to optimize the mechanical design of the fixation and refine the rehabilitation program. Understanding the load applied on the fixation is a crucial step towards this goal. METHODS: The load applied on the osseointegrated fixation of nine transfemoral amputees was measured using a load transducer, when the amputees performed activities which included straight-line level walking, ascending and descending stairs and a ramp as well as walking around a circle. Force and moment patterns along each gait cycle, magnitudes and time of occurrence of the local extrema of the load, as well as impulses were analysed. FINDINGS: Managing a ramp and stairs, and walking around a circle did not produce a significant increase (P>0.05) in load compared to straight-line level walking. The patterns of the moment about the medio-lateral axis were different among the six activities which may reflect the different strategies used in controlling the prosthetic knee joint. INTERPRETATIONS: This study increases the understanding of biomechanics of bone-anchored osseointegrated prostheses. The loading data provided will be useful in designing the osseointegrated fixation to increase the fatigue life and to refine the rehabilitation protocol.
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| 11. |
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| 12. |
- Sjödahl, Jenny, et al.
(författare)
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The postural response of the pelvic floor muscles during limb movements : A methodological electromyography study in parous women without lumbopelvic pain
- 2009
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Ingår i: CLINICAL BIOMECHANICS. - : Elsevier BV. - 0268-0033. ; 24:2, s. 183-189
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Tidskriftsartikel (refereegranskat)abstract
- Background: Pregnancy-related lumbopelvic pain is common. More than 30% of women have persistent pain 3 months after giving birth. There is no consensus regarding the pathology. However, coordination of muscle activity by appropriate timing and amplitude is necessary for maintaining adequate stability in the lumbopelvic area. The aim was to develop a method using surface electromyography to detect a feed-forward response in the pelvic floor muscles during limb movements performed at a comfortable speed applicable in future studies for women with lumbopelvic pain. Methods: Ten parous women with no lumbopelvic pain in the past 12 months were included. Surface electromyographic activity was recorded from the pelvic floor muscles and unilaterally from transversus abdominis/internal oblique, rectus abdominis, erector spinae, hip adductors, rectus femoris and deltoid. The subjects performed leg lift in supine and arm lift from standing. The electromyographic onset was related to the initiation of the movement. Findings: In the majority of the women the electromyographic onsets of the pelvic floor muscles occurred before the movement was initiated, regardless of whether it was a leg or an arm lift. In addition. electromyographic onsets for the other muscles, except the rectus abdominis during the arm lift, also occurred prior to the movements. Interpretation: The findings suggest a feed-forward response in the pelvic floor muscles during leg and arm lifts in women who had previously given birth and were without lumbopelvic pain. Movements performed at a comfortable speed seem to be useful in order to detect such a response.
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| 13. |
- Tange Kristensen, Morten, et al.
(författare)
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Knee-extension strength, postural control and function are related to fracture type and thigh edema in patients with hip fracture.
- 2009
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Ingår i: Clinical Biomechanics. - : Elsevier BV. - 0268-0033. ; 24, s. 218-224
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Post-surgery thigh edema, loss of knee-extension strength, and reduced physical performance are common following a hip fracture. It is not known if knee-extension strength and physical performance are related to the edema and fracture type. The aim of this study was to examine the influence of fracture type and post-surgery edema on physical performances in patients with hip fracture. METHODS: Fifteen women and five men admitted from their own home to an acute orthopedic hip fracture unit were examined. Ten had cervical and ten had intertrochanteric fractures. Correlations between fracture type and thigh edema in the fractured limb (% non-fractured) to physical performances of basic mobility, postural control (sway), and isometric knee-extension strength were examined. All measures, except those of basic mobility, were conducted at the time of discharge, 8.5 days post-surgery. FINDINGS: Patients with intertrochanteric fractures had greater edema (111% non-fractured limb) compared with cervical fractures (104% non-fractured, P<0.001). Thigh edema was significantly correlated to lower scores of basic mobility (r=-0.61, P=0.004), reduced postural control (r=0.67, P=0.001), and fractured limb knee-extension strength deficit ([% non-fractured], r=-0.77, P<0.001), explaining between 32% and 59% of the variance (r(2)) in performances. INTERPRETATION: Our results indicate that fracture type and the corresponding thigh edema are important factors influencing physical performances after hip fracture. These findings have important implications for rehabilitation programs and for further research in patients with hip fracture.
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