Journal of biomechanics
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Journal of biomechanics · Dec 2020
Assessment of mechanical properties of articular cartilage with quantitative three-dimensional ultrashort echo time (UTE) cones magnetic resonance imaging.
Conventional magnetic resonance imaging (MRI) is not capable of detecting signal from the deep cartilage due to its short transverse relaxation time (T2). Moreover, several quantitative MRI techniques are significantly influenced by the magic angle effect. The combinations of ultrashort echo time (UTE) MRI with magnetization transfer (UTE-MT) and Adiabatic T1ρ (UTE-AdiabT1ρ) imaging allow magic angle-insensitive assessments of all regions of articular cartilage. ⋯ Correlations between other UTE MRI measurements (T2*, T1, and T2mm) and mechanical properties were non-significant. The 3D UTE-AdiabT1ρ and UTE-MT sequences were highlighted as promising surrogates for non-invasive assessment of cartilage mechanical properties. MMF from UTE-MT modeling showed the highest correlations with cartilage mechanics.
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Journal of biomechanics · Nov 2020
Between-session reliability of subject-specific musculoskeletal models of the spine derived from optoelectronic motion capture data.
This study evaluated the between-session reliability of creating subject-specific musculoskeletal models with optoelectronic motion capture data, and using them to estimate spine loading. Nineteen healthy participants aged 24-74 years underwent the same set of measurements on two separate occasions. Retroreflective markers were placed on anatomical regions, including C7, T1, T4, T5, T8, T9, T12 and L1 spinous processes, pelvis, upper and lower limbs, and head. ⋯ Spine curvature measures showed excellent reliability (ICC = 0.79-0.91) and body scaling segments showed fair to excellent reliability (ICC = 0.46-0.95). We found that musculoskeletal models showed mostly excellent between-session reliability to estimate spine loading, with 91% of ICC values > 0.75 for all activities. This information is a necessary precursor for using motion capture data to estimate spine loading from subject-specific musculoskeletal models, and suggests that marker data will deliver reproducible subject-specific models and estimates of spine loading.
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Journal of biomechanics · Nov 2020
A comparison of balance-correcting responses induced with platform-translation and shoulder-pull perturbation methods.
The understanding of reactive balance control mechanisms in humans emanates from studies utilizing a variety of perturbation methods, instructions, and sensory conditions. The use of different perturbation methods may produce method-specific balance-correcting responses. This study evaluated balance-correcting responses induced with platform-translation and shoulder-pull methods with equilibrated perturbation intensities, and whether the absence of vision affects balance-correcting responses differently between perturbation methods. ⋯ During platform-translation trials participants demonstrated smaller MOS which placed them in a less favorable circumstance for balance recovery. Platform-translation appears to be more challenging than shoulder-pull perturbation in terms of balance recovery. This study underscores that caution is required when interpreting results of studies utilizing different perturbation paradigms.
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Journal of biomechanics · May 2020
Finite element analysis of MitraClip procedure on a patient-specific model with functional mitral regurgitation.
Mitral valve (MV) repair with the MitraClip device has been shown to reduce mitral regurgitation severity and improve clinical outcomes in symptomatic patients at high surgical risk. MitraClip was recently approved in the US for the treatment of functional mitral regurgitation (FMR), which significantly expands the number of patients that can be treated with this device. This study aims to quantify the morphologic changes and evaluate the biomechanical interaction between the MitraClip device and the mitral apparatus of a real patient case with FMR using computational modeling. ⋯ Anterior and posterior leaflet peak stresses increased by up to 64% and 62% after clip placement, respectively, and were located at the region of clip grasp. Similarly, anterior and posterior leaflet peak strains increased by up to 20% and 10%, respectively. FE modeling, as used here, can be a powerful tool to examine the complex MitraClip-host biomechanical interaction.
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Journal of biomechanics · May 2020
Effects of nucleus pulposus location on spinal loads and joint centers of rotation and reaction during forward flexion: A combined finite element and Musculoskeletal study.
The mechanical environment of the intervertebral disc and spinal loads are intimately associated with low back pain (LBP) caused by mechanical load. The cause and effect relationship between postures and pain has been therapeutically investigated and widely used to guide patient care. Shift of the nucleus pulposus (NP) inside the intervertebral disc when the spine changes posture in the sagittal plane, known also as NP migration, has been observed and quantified in in-vivo studies. ⋯ The results showed that intradiscal pressure (IDP) and compressive force are sensitive to the nucleus location while the effects on the center of rotation (CoR), center of reaction (CTR) and moment rotation curves were negligible. Also, our findings revealed that FE models should consider the effects of NP location during bending to predict more realistic results as the nucleus displacement caused by disc bulge predicted by these models is much smaller than the real shift observed in in-vivo. In addition, this study confirmed that position of the rigid joint in MSK models that fix this latter to the CoR, must be modelled carefully for more accurate muscle forces and spinal loads prediction.