Orthopaedic Basic Science Journal Scan

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Demineralized bone matrix and platelet-rich plasma do not improve healing of osteochondral defects of the talus: an experimental goat study.

Osteoarthritis Cartilage. 2013 Jul 26;

Authors: van Bergen CJ, Kerkhoffs GM, Ozdemir M, Korstjens CM, Everts V, van Ruijven LJ, van Dijk CN, Blankevoort L

Abstract
OBJECTIVE: The purpose of this study was to evaluate the effectiveness of demineralized bone matrix (DBM) with and without platelet-rich plasma (PRP) in the treatment of osteochondral defects (OCDs) of the talus. We hypothesized that treatment with DBM would result in more bone formation than no treatment in control OCDs, and that PRP would further enhance the regenerative capacity of DBM.
METHOD: A standardized 6-mm OCD was created in each talus of 16 adult goats. According to a randomization scheme, one OCD of each goat was treated with allogeneic DBM hydrated with normal saline (n = 8) or hydrated with autologous PRP (n = 8). The contralateral OCD (n = 16) served as control. After 24 weeks, the animals were euthanized and the tali excised. Various outcome parameters were analyzed with use of macroscopic evaluation, micro-computed tomography, histology, histomorphometry, and fluorescence microscopy.

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Surfactant treatments influence drying mechanics in human stratum corneum.

J Biomech. 2013 Jul 25;

Authors: German GK, Pashkovski E, Dufresne ER

Abstract
We describe a high-throughput method capable of quantifying the elastic modulus and drying stress of ex vivo samples of human stratum corneum. Spatially resolved drying deformations in circular tissue samples are measured, azimuthally averaged and fitted with a profile based on a linear elastic model. Our approach enables the comparison of the physical effects of different cleansers. We find that cleansing can cause dramatic changes to the mechanical properties of stratum corneum. In some cases, cleansing can lead to an order of magnitude increase in elastic modulus and drying stress. We expect that these mechanical properties have a direct impact on cracking and chapping skin as well as the milder sensation of perceived tightness often experienced after washing. Mechanical drying studies are also combined with drop wetting studies and pyranine staining experiments. This combination of techniques allows one to establish a multidimensional profile of stratum corneum including stiffness, susceptibility to drying, hydrophilicity and barrier functionality.

PMID: 23891567 [PubMed - as supplied by publisher]

Read more... http://www.ncbi.nlm.nih.gov/pubmed/23891567?dopt=Abstract

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Energy cost of balance control during walking decreases with external stabilizer stiffness independent of walking speed.

J Biomech. 2013 Jul 26;

Authors: Ijmker T, Houdijk H, Lamoth CJ, Beek PJ, van der Woude LH

Abstract
Human walking requires active neuromuscular control to ensure stability in the lateral direction, which inflicts a certain metabolic load. The magnitude of this metabolic load has previously been investigated by means of passive external lateral stabilization via spring-like cords. In the present study, we applied this method to test two hypotheses: (1) the effect of external stabilization on energy cost depends on the stiffness of the stabilizing springs, and (2) the energy cost for balance control, and consequently the effect of external stabilization on energy cost, depends on walking speed. Fourteen healthy young adults walked on a motor driven treadmill without stabilization and with stabilization with four different spring stiffnesses (between 760 and 1820Nm(-1)) at three walking speeds (70%, 100%, and 130% of preferred speed). Energy cost was calculated from breath-by-breath oxygen consumption. Gait parameters (mean and variability of step width and stride length, and variability of trunk accelerations) were calculated from kinematic data. On average external stabilization led to a decrease in energy cost of 6% (p<0.005) as well as a decrease in step width (24%; p<0.001), step width variability (41%; p<0.001) and

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On the accuracy of the Head Impact Telemetry (HIT) System used in football helmets.

J Biomech. 2013 Jul 25;

Authors: Jadischke R, Viano DC, Dau N, King AI, McCarthy J

Abstract

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Individual density-elasticity relationships improve accuracy of subject-specific finite element models of human femurs.

J Biomech. 2013 Jul 26;

Authors: Eberle S, Göttlinger M, Augat P

Abstract
In a previous study on subject-specific finite-element-models, we found that appropriate density-elasticity relationships to compute the mechanical behavior of femurs seem to be subject-specific. The purpose of this study was to test the hypothesis that the predictive error of a cohort of subject-specific finite element-models is lower with subject-specific density-elasticity relationships than with a cohort-specific density-elasticity relationship. Finite-element-analysis and inverse optimization based on response surface methodology were employed to test the hypothesis. Subject-specific FE-models of 17 human femurs and corresponding experimental data from biomechanical tests were taken from a previous study. A power function for the relation between radiological bone density and elastic modulus was set up with the optimization variables a and b: E(MPa)=aρqCT(b)(gK2HPO4/cm(3)). The goal of the optimization was to minimize the root-mean-square error in percent (RMSE%) between computational and experimental results. A Wilcoxon test (p=0.05) was performed on all absolute relative errors between the two groups (subject-specific functions vs. cohort-specific function). The subject-specific functions resulted in a 6% lower overall prediction error and a 6%

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Functional limits of agreement applied as a novel method comparison tool for accuracy and precision of inertial measurement unit derived displacement of the distal limb in horses.

J Biomech. 2013 Jul 23;

Authors: Olsen E, Pfau T, Ritz C

Abstract

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Effects of growth on residual stress distribution along the radial depth of cortical cylinders from bovine femurs.

J Biomech. 2013 Jul 26;

Authors: Yamada S, Tadano S

Abstract

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MOSHFIT: Algorithms for occlusion-tolerant mean shape and rigid motion from 3D movement data.

J Biomech. 2013 Jul 23;

Authors: Mitchelson JR

Abstract

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COMP-Ang1 promotes chondrogenic and osteogenic differentiation of multipotent mesenchymal stem cells through the Ang1/Tie2 signaling pathway.

J Orthop Res. 2013 Jul 24;

Authors: Kim S, Lee JC, Cho ES, Kwon J

Abstract