Showing papers in "Journal of Biomechanics in 1999"

TL;DR: In this paper, an isotropic elastic modulus was calculated from the unloading curve with an assumed Poisson ratio of 0.3, while hardness was defined as the maximal force divided by the corresponding contact area.

TL;DR: It is suggested that, with joint constraints and a global error compensation scheme, the effects of measurement errors on the reconstruction of the musculoskeletal system and subsequent mechanical analyses can be reduced globally.

TL;DR: It is demonstrated that maximum knee motion may not necessarily correspond to the highest in-situ forces in the anterior cruciate ligament (ACL) during a simulated isometric extension motion of the knee and that hamstring co-contraction with quadriceps is effective in reducing excessive force in the ACL.

TL;DR: This study supports the philosophy that a child should be taught 'proper' pitching mechanics for use throughout a career, and appears that the natural progression for successful pitching is to learn proper mechanics as early as possible, and build strength as the body matures.

TL;DR: The results suggest that elasticity of trabecular tissue is within the range of that of cortical bone tissue and that nanoindentation as a technique for measurement of Young's modulus in anisotropic bone is not limited.

TL;DR: In the computations, the shear thinning behavior of the analog blood fluid was incorporated through the Carreau-Yasuda model, and this seems to be the dominant non-Newtonian property of the blood analog fluid under steady flow conditions.

TL;DR: The functional method performed significantly better and estimated HJCs within a rms distance of 13 mm on average and is suggested for use in motion analysis when the subject's hip range of motion is not limited.

TL;DR: Three-dimensional FE models are a promising method for predicting fracture load, and may be useful in monitoring strength changes in vivo and Planned refinements of the FE technique are expected to further improve these results.

TL;DR: There is a difference between the theoretically calculated length change and the kinematically measured length changes of the spring-mass model and the leg spring stiffness, the ankle spring stiffness and the knee spring stiffness are influenced by running speed, which is influenced mostly by changes in stiffness at the knee joint.

TL;DR: This study found that runners completely adjusted leg stiffness for their first step on the new surface after the transition, and made a smooth transition between surfaces so that the path of the center of mass was unaffected by the change in surface stiffness.

TL;DR: It is concluded that the primary mechanism for leg stiffness adjustment is the adjustment of ankle stiffness, and that leg stiffness was approximately twice as great for maximum height hopping as for preferred height hopping.

TL;DR: Evidence from experiments involving tenotomy, fasciatomy and aponeurotomy regarding its importance is presented, implications for thinking about muscle(s) and movement are considered and they are considered to be stronger than direct tensile transmission.

TL;DR: In this paper, a numerical and experimental investigation of unsteady entry flow in a 90 degrees curved tube is presented to study the impact of the non-Newtonian properties of blood on the velocity distribution.

TL;DR: Enhancing the activation of the gluteus maximus, a muscle that is frequently underactive in persons with cerebral palsy, may help correct excessive flexion and internal rotation of the hip.

TL;DR: A simple mathematical model is presented that describes the passive elastic joint properties of the hip, knee, and ankle joint on the basis of a double-exponential expression and can be implemented in biomechanical models of the lower extremities, which are generally used for the simulation of multi-joint movements.

TL;DR: The IAP mechanism for stabilizing the lumbar spine appears preferable in tasks that demand trunk extensor moment such as lifting or jumping because it can increase spine stability without the additional coactivation of erector spinae muscles.

TL;DR: The mechanical and volumetric properties determined in this study will be of use in analytical and finite element models of chondrocyte-matrix interactions in order to better predict the mechanical environment of the cell in vivo.

TL;DR: Predictors of peak pressure underneath the human foot during walking are identified and insight is given into potential etiological factors associated with elevated plantar pressure and direction is provided for future studies designed to reduce elevated pressure in "at-risk" patients.

TL;DR: A large deformation, linear, viscoelastic model, suitable for direct use with commercially available finite element software packages such as ABAQUS is constructed and the agreement between the proposed theoretical model and the experiment is good.

TL;DR: The amount of predicted bone loss, measured quantitatively by simulating DEXA on finite element models, was found to be inversely correlated with the initial bone mineral content, and can therefore be explained by mechanically induced remodelling.

TL;DR: It has been concluded that changes in muscle activity (muscle tuning) can be used as a possible strategy to affect vertical impact force peaks during running.

TL;DR: Data from a systematic study into cartilage compression of intact human femoro-patellar joints under short- and long-term static loading with MR imaging may be used to compute the load partitioning between the solid matrix and fluid phase, and to elucidate the etiologic factors relevant in mechanically induced osteoarthritis.

TL;DR: The data show that care must be taken when applying thresholds in generating 3-D data, and that a fixed threshold may be used to obtain reliable volume fraction data.

TL;DR: A protocol to obtain the joint angles of wrist and elbow from tracked triads of surface markers on each limb segment shows that the model assumptions are reasonable and that accurate joint rotations can be obtained.

TL;DR: It was deduced that the ankle is a single-degree-of-freedom mechanism where mobility is allowed by the sliding of the articular surfaces upon each other and the isometric rotation of two ligaments about their origins and insertions, without tissue deformation.

TL;DR: The results support the hypothesis; for practical purposes, the concept of an 'effective isotropic tissue modulus' concept is a viable one and it is suggested that the value of such a modulus for individual cases might be inferred from the average tissue density, hence the degree of mineralization.

TL;DR: A rough bone implant surface was conceptualized as being built up of pits of different sizes and of different shapes, and a surface roughness parameter was derived, the pit effectivity factor (fpe), which describes how effective the individual pits of the rough surface are as retention elements with regard to shear.

TL;DR: It is concluded that the "Flock of Birds" is a useful tool for shoulder kinematic studies and applications in terms of measurement accuracy of the electromagnetic tracking device in shoulder research is investigated.

TL;DR: The goal of this study was to provide unique and novel insights into the underlying motor mechanisms used in postural control by determining the joint moments during balance recovery from medio-lateral (M/L) perturbations.

TL;DR: Results indicate that trabecular bone tissue has a safety factor of approximately two for hip-joint loads that occur during normal activities, and indicates that no single load creates even stress or strain distributions in the trABecular architecture.