Gait & posture
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Compensatory mechanisms in below-knee amputee gait are necessary due to the functional loss of the ankle muscles, especially at higher walking speeds when the mechanical energetic demands of walking are greater. The objective of this study was to examine amputee anterior/posterior (A/P) ground reaction force (GRF) impulses and joint kinetics across a wide range of steady-state walking speeds to further understand the compensatory mechanisms used by below-knee amputees. We hypothesized that amputees would rely more on their intact leg to generate greater propulsion relative to the residual leg, which would result in greater GRF asymmetry between legs as walking speed increased. ⋯ The primary compensatory mechanism was greater positive residual leg hip joint power and work in early stance, which led to increased propulsion from the residual leg as walking speed increased. In addition, amputees had reduced residual leg positive knee work in early stance, suggesting increased output from the biarticular hamstrings. Thus, increasing residual leg hip extensor strength and output may be a useful mechanism to reduce GRF loading asymmetry between the intact and residual legs.
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Lumbar spine pathology accounts for billions of dollars in societal costs each year. Although the symptomatology of these conditions is relatively well understood, the mechanical changes in the spine are not. Previous direct measurements of lumbar spine mechanics have mostly been performed on cadavers. ⋯ Using a direct (pin-based) in vivo measurement method, the motion of the human lumbar spine during gait was found to be triaxial. This appears to be the first three-dimensional motion analysis of the entire lumbar spine using indwelling pins. The results were similar to previously published data derived from a variety of experimental methods.
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Comparative Study
Reliability and validity of the Edinburgh Visual Gait Score for cerebral palsy when used by inexperienced observers.
The Edinburgh Visual Gait Score (EVGS) for cerebral palsy has been validated for observer reliability and validity for observers experienced in gait analysis. This study investigated the reliability and validity of the EVGS for observers inexperienced in gait analysis. Six medical students used the score to analyse videotapes from the original study by Read et al. [Read HS, Hazlewood ME, Hillman SJ, Prescott RJ, Robb JE. ⋯ There was complete agreement for 52% of the 10 numerical items with 3D-gait analysis data for inexperienced observers compared to 64% for experienced observers. Ranking of reliability of individual items was similar between the two groups and was generally best for events occurring at the foot and ankle. Observations of gait events by the inexperienced observers using the EVGS were reasonably reliable but not very accurate when compared to experienced observers and 3D-gait analysis.
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Modulating speed over a large range is important in walking, yet understanding how the neuromotor patterns adapt to the changing energetic demands of different speeds is not well understood. The purpose of this study was to identify functional and energetic adaptations in individual muscles in response to walking at faster steady-state speeds using muscle-actuated forward dynamics simulations. The simulation data were invariant with speed as to whether muscles contributed to trunk support, forward propulsion or leg swing. ⋯ The results also highlighted the importance of initiating and controlling leg swing as there was a dramatic increase at the higher walking speeds in iliopsoas muscle work to accelerate the leg in pre- and early swing, and an increase in the biarticular hamstring muscle work to decelerate the leg in late swing. In addition, walking near self-selected speeds (1.2m/s) improves the utilization of elastic energy storage and recovery in the uniarticular ankle plantar flexors and reduces negative fiber work, when compared to faster or slower speeds. These results provide important insight into the neuromotor mechanisms underlying speed regulation in walking and provide the foundation on which to investigate the influence of walking speed on various neuromotor measures of interest in pathological populations.
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This study investigated the relationship between the quality of life, quality of gait and the quantity of gait in patients with impairments in the lower extremities. ⋯ The findings underline that a patient's level of mobility cannot be reliably estimated from quality of gait or from quality of life. Instead, adequate methods should be chosen to measure the quantity of gait in daily life.