The biomechanical fingerprint of hip and knee osteoarthritis patients during activities of daily living

Background: Osteoarthritis is a highly prevalent disease affecting the hip and knee joint and is characterized by load-mediated pain and decreased quality of life. Dependent on involved joint, patients present antalgic movement compensations, aiming to decrease loading on the involved joint. However, the associated alterations in mechanical loading of the ipsi- and contra-lateral lower limb joints, are less documented. Here, we documented the biomechanical fingerprint of end-stage hip and knee osteoarthritis patients in terms of ipsilateral and contralateral hip and knee loading during walking and stair ambulation. Methods: Three-dimensional motion-analysis was performed in 20 hip, 18 knee osteoarthritis patients and 12 controls during level walking and stair ambulation. Joint contact forces were calculated using a standard musculoskeletal modelling workflow in Opensim. Involved and contralateral hip and knee joint loading was compared against healthy controls using independent t-tests (p &lt; 0.05). Findings: Both hip and knee cohorts significantly decreased loading of the involved joint during gait and stair ambulation. Hip osteoarthritis patients presented no signs of ipsilateral knee nor contralateral leg overloading, during walking and stair ascending. However, knee osteoarthritis patients significantly increased loading at the ipsilateral hip, and contralateral hip and knee joints during stair ambulation compared to controls. Interpretation: The biomechanical fingerprint in knee and hip osteoarthritis patients confirmed antalgic movement strategies to unload the involved leg during gait. Only during stair ambulation in knee osteoarthritis patients, movement adaptations were confirmed that induced unbalanced intra- and inter-limb loading conditions, which are known risk factors for secondary osteoarthritis.</p

The biomechanical fingerprint of hip and knee osteoarthritis patients during activities of daily living

Background: Osteoarthritis is a highly prevalent disease affecting the hip and knee joint and is characterized by load-mediated pain and decreased quality of life. Dependent on involved joint, patients present antalgic movement compensations, aiming to decrease loading on the involved joint. However, the associated alterations in mechanical loading of the ipsi- and contra-lateral lower limb joints, are less documented. Here, we documented the biomechanical fingerprint of end-stage hip and knee osteoarthritis patients in terms of ipsilateral and contralateral hip and knee loading during walking and stair ambulation. Methods: Three-dimensional motion-analysis was performed in 20 hip, 18 knee osteoarthritis patients and 12 controls during level walking and stair ambulation. Joint contact forces were calculated using a standard musculoskeletal modelling workflow in Opensim. Involved and contralateral hip and knee joint loading was compared against healthy controls using independent t-tests (p &lt; 0.05). Findings: Both hip and knee cohorts significantly decreased loading of the involved joint during gait and stair ambulation. Hip osteoarthritis patients presented no signs of ipsilateral knee nor contralateral leg overloading, during walking and stair ascending. However, knee osteoarthritis patients significantly increased loading at the ipsilateral hip, and contralateral hip and knee joints during stair ambulation compared to controls. Interpretation: The biomechanical fingerprint in knee and hip osteoarthritis patients confirmed antalgic movement strategies to unload the involved leg during gait. Only during stair ambulation in knee osteoarthritis patients, movement adaptations were confirmed that induced unbalanced intra- and inter-limb loading conditions, which are known risk factors for secondary osteoarthritis.</p

Equation of State for Macromolecules of Variable Flexibility in Good Solvents: A Comparison of Techniques for Monte Carlo Simulations of Lattice Models

The osmotic equation of state for the athermal bond fluctuation model on the simple cubic lattice is obtained from extensive Monte Carlo simulations. For short macromolecules (chain length N=20) we study the influence of various choices for the chain stiffness on the equation of state. Three techniques are applied and compared in order to critically assess their efficiency and accuracy: the repulsive wall method, the thermodynamic integration method (which rests on the feasibility of simulations in the grand canonical ensemble), and the recently advocated sedimentation equilibrium method, which records the density profile in an external (e.g. gravitation-like) field and infers, via a local density approximation, the equation of state from the hydrostatic equilibrium condition. We confirm the conclusion that the latter technique is far more efficient than the repulsive wall method, but we find that the thermodynamic integration method is similarly efficient as the sedimentation equilibrium method. For very stiff chains the onset of nematic order enforces the formation of isotropic-nematic interface in the sedimentation equilibrium method leading to strong rounding effects and deviations from the true equation of state in the transition regime.Comment: 32 pages, 18 figures, submitted to Phys.Rev.E; one paragraph added to conclusions sectio

Hoe vlaamse jongeren biologische evolutie bekijken in hat jaar 2002: Persoon en gemeenschap

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