Biomechanics Laboratory

Portland, OR, United States

Biomechanics Laboratory

Portland, OR, United States
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Horn J.,Section of Children's Orthopedics and Reconstructive Surgery | Steen H.,Biomechanics Laboratory | Huhnstock S.,Section of Children's Orthopedics and Reconstructive Surgery | Hvid I.,Section of Children's Orthopedics and Reconstructive Surgery | Gunderson R.B.,University of Oslo
Acta Orthopaedica | Year: 2017

Background and purpose — Hexapod ring fixators such as the Taylor Spatial Frame (TSF) have shown good outcomes. However, there have only been a few studies comparing the use of TSF with various etiologies of the deformity. We compared the use of TSF in congenital and acquired deformities in children. Patients and methods — We reviewed 213 lower extremity reconstructive procedures with the TSF in 192 patients who were operated between October 2000 and October 2015. 128 procedures (67 proximal tibiae, 51 distal femora, and 10 distal tibiae) in 117 children (median age 14 (4–18) years; 59 girls) fulfilled the inclusion criteria. 89 procedures were done in children with congenital deformities (group C) and 39 were done in children with acquired deformities (group A). Outcome parameters were lengthening and alignment achieved, lengthening index, complications, and analysis of residual deformity in a subgroup of patients. Results — Mean lengthening achieved was 3.9 (1.0–7.0) cm in group C and 3.7 (1.0–8.0) cm in group A (p = 0.5). Deformity parameters were corrected to satisfaction in all but 3 patients, who needed further surgery for complete deformity correction. However, minor residual deformity was common in one-third of the patients. The mean lengthening index was 2.2 (0.8–10) months/cm in group C and 2.0 (0.8–6) months/cm in group A (p = 0.7). Isolated analysis of all tibial and femoral lengthenings showed similar lengthening indices between groups. Complication rates and the need for secondary surgery were much greater in the group with congenital deformities. Interpretation — The TSF is an excellent tool for the correction of complex deformities in children. There were similar lengthening indices in the 2 groups. However, congenital deformities showed a high rate of complications, and should therefore be addressed with care. © 2017 The Author(s). Published by Taylor & Francis on behalf of the Nordic Orthopedic Federation.

Miri A.K.,Biomechanics Laboratory | Mongeau L.,Biomechanics Laboratory | Wiseman P.W.,McGill University
Laryngoscope | Year: 2012

Objectives/Hypothesis: The purpose of this work was to apply nonlinear laser scanning microscopy (NLSM) for visualizing the morphology of extracellular matrix proteins within human vocal folds. This technique may potentially assist clinicians in making rapid diagnoses of vocal fold tissue disease or damage. Microstructural characterization based on NLSM provides valuable information for better understanding molecular mechanisms and tissue structure. Study Design: Experimental, ex vivo human vocal fold. Methods: A custom-built multimodal nonlinear laser scanning microscope was used to scan fibrillar proteins in three 4% formaldehyde-fixed cadaveric samples. Collagen and elastin, key extracellular matrix proteins in the vocal fold lamina propria, were imaged by two nonlinear microscopy modalities: second harmonic generation (SHG) and two-photon fluorescence (TPF), respectively. An experimental protocol was introduced to characterize the geometrical properties of the imaged fibrous proteins. Results: NLSM revealed the biomorphology of the human vocal fold fibrous proteins. No photobleaching was observed for the incident laser power of â̂1/260 mW before the excitation objective. Types I and III fibrillar collagen were imaged without label in the tissue by intrinsic SHG. Imaging while rotating the incident laser light-polarization direction confirmed a helical shape for the collagen fibers. The amplitude, periodicity, and overall orientation were then computed for the helically distributed collagen network. The elastin network was simultaneously imaged via TPF and found to have a basket-like structure. In some regions, particularly close to the epithelium, colocalization of both extracellular matrix components were observed. Conclusions: A benchmark study is presented for quantitative real-time, ex vivo, NLSM imaging of the extracellular macromolecules in human vocal fold lamina propria. The results are promising for clinical applications. © 2011 The American Laryngological.

Chanlalit C.,Bangkok University | Chanlalit C.,Biomechanics Laboratory | Fitzsimmons J.S.,Biomechanics Laboratory | Shukla D.R.,Biomechanics Laboratory | And 2 more authors.
Journal of Shoulder and Elbow Surgery | Year: 2011

Background: Initial stability of a textured surface prosthetic stem is necessary for bone in-growth. Surfaces currently used for radial head prostheses include titanium plasma spray and grit-blasted titanium. Hypothesis: Plasma spray radial head prosthetic stems are less dependent than grit-blasted stems on a tight press fit. Good initial press-fit stability, with acceptable micro-motion, can be achieved with a greater range of stem sizes using a plasma spray than grit-blasted surface. Methods: Paired cadaveric radii were implanted with plasma spray or grit-blasted radial head prosthetic stems. Micromotion at the stem tip was measured under circumstances simulating eccentric loads. Results: Micromotion in the plasma spray (PS) stems (49 ± 37) μm was not better than that in the grit-blasted (GB) stems (28 ± 10) μm (P = .13). Micromotion of less than 100 μm was measured in all 12 GB stems that were maximum or 1 mm less than maximum size, versus 5/6, and 4/6 PS stems, respectively. Discussion: Micromotion in plasma spray prosthetic radial head stems was not better than that seen in grit-blasted stems, contrary to our initial hypothesis. Conclusion: Grit-blasted prosthetic radial head stems confer initial press-fit stability that is as good as, or slightly better than, corresponding plasma spray stems. Acceptable amounts of micromotion can be achieved with 2 grit-blasted stem sizes and probably with 2 plasma spray stem sizes. © 2011 Journal of Shoulder and Elbow Surgery Board of Trustees.

Casamichana D.,University of the Basque Country | Castellano J.,University of the Basque Country | Castagna C.,Biomechanics Laboratory
Journal of Strength and Conditioning Research | Year: 2012

This study compared the physical demands of friendly matches (FMs) and small-sided games (SGs) in semiprofessional soccer players by means of global positioning system technology. Twenty-seven semiprofessional soccer players were monitored during 7 FMs and 9 sessions involving different SGs. Their physical profile was described on the basis of 20 variables related to distances and frequencies at different running speeds, the number of accelerations, and through global indicators of workload such as the work:rest ratio, player workload, and the exertion index. Results showed significant differences (p<0.01) between SGs and FMs for the following variables: overall workload (SG > FM); the distribution of the distance covered in the speed zones 7.0-12.9 km·h -1 (SG > FM) and .21 km·h -1 (FM > SG); the distribution of time spent in certain speed zones (FM > SG: 0.0-6.9 and >21 km·h -1; FM > SG: 7.0-12.9 km·h -1). More sprints per hour of play were performed during FMs, with greater mean durations and distances, greater maximum durations and distances, and a greater frequency per hour of play for sprints of 10-40 and >.40 m (p < 0.01). The frequency of repeated high-intensity efforts was higher during FM (p < 0.01). The results show that coaches and strength and conditioning professionals should consider FMs during their training routine to foster specific adaptations in the domain of high-intensity effort. © 2012 National Strength and Conditioning Association.

Lanzer P.,Gesundheitszentrum Bitterfeld | Gijsen F.J.H.,Biomechanics Laboratory | Topoleski L.D.T.,University of Maryland Baltimore County | Holzapfel G.A.,Graz University of Technology | Holzapfel G.A.,KTH Royal Institute of Technology
Herz | Year: 2010

At present, the product information of intracoronary stents provided by the industry contains only limited technical data restricting judgments on the in vivo performance of individual products. Available experimental and clinical evidence suggests that interventional target sites display highly heterogeneous biomechanical behavior needed to be matched by specific stent and stent delivery system characteristics. To allow individualized stent-lesion matching, both, understanding of biomechanical properties of the atherosclerotic coronary artery lesions and expert knowledge of the intracoronary stent systems, are required. Here, the authors review some of the initial data on mechanical properties of coronary artery lesions potentially relevant to stenting and suggest standards for technical documentation of intracoronary stents. © 2010 Urban and Vogel.

PubMed | University Pompeu Fabra, Hospital Mataro, Biomechanics Laboratory, Hospitalet General Hospital and CIBER ISCIII
Type: Comparative Study | Journal: Lung | Year: 2016

Muscular dysfunction has been described as one of the systemic manifestations of chronic obstructive pulmonary disease (COPD).The aim of this study was to evaluate muscular strength of the different anatomical compartments in patients with severe COPD compared with healthy controls.We performed a cross-sectional study in patients with severe COPD. We evaluated the muscular strength of the respiratory muscles, flexors and extensors of the cervical spine and knee, as well as handgrip force. The 6-min walking test (6MWT) and serum inflammatory markers were also analysed.Twenty-eight male patients with COPD (mean age 67.8years, mean FEV1 (%) 39%) and 24 male healthy controls (mean age 70.2years) were studied. The strength of the flexors and extensors of the knee was significantly reduced in patients with COPD (p<0.001 and p=0.003). No differences were observed in the flexors and extensors of the cervical spine and handgrip force between groups. No correlation was observed between the muscular strength in the different anatomic compartments and the concentrations of blood inflammatory biomarkers or the metres walked in the 6MWT in COPD patients. However, a significant negative linear correlation was observed between the 6MWT and IL-6 and IL-8 levels (rho=-0.67, p=0.001; rho=-0.57, p=0.008). In addition, we found a negative correlation between the 6MWT and inspiratory capacity (rho=-0.755, p=0.031).Our results suggest that muscular dysfunction in patients with COPD differs in different muscular compartments. The main factor for a reduced exercise capacity was a reduction in inspiratory capacity.

PubMed | Leiden University and Biomechanics Laboratory
Type: Journal Article | Journal: BMC bioinformatics | Year: 2016

Endocytosis is regarded as a mechanism of attenuating the epidermal growth factor receptor (EGFR) signaling and of receptor degradation. There is increasing evidence becoming available showing that breast cancer progression is associated with a defect in EGFR endocytosis. In order to find related Ribonucleic acid (RNA) regulators in this process, high-throughput imaging with fluorescent markers is used to visualize the complex EGFR endocytosis process. Subsequently a dedicated automatic image and data analysis system is developed and applied to extract the phenotype measurement and distinguish different developmental episodes from a huge amount of images acquired through high-throughput imaging. For the image analysis, a phenotype measurement quantifies the important image information into distinct features or measurements. Therefore, the manner in which prominent measurements are chosen to represent the dynamics of the EGFR process becomes a crucial step for the identification of the phenotype. In the subsequent data analysis, classification is used to categorize each observation by making use of all prominent measurements obtained from image analysis. Therefore, a better construction for a classification strategy will support to raise the performance level in our image and data analysis system.In this paper, we illustrate an integrated analysis method for EGFR signalling through image analysis of microscopy images. Sophisticated wavelet-based texture measurements are used to obtain a good description of the characteristic stages in the EGFR signalling. A hierarchical classification strategy is designed to improve the recognition of phenotypic episodes of EGFR during endocytosis. Different strategies for normalization, feature selection and classification are evaluated.The results of performance assessment clearly demonstrate that our hierarchical classification scheme combined with a selected set of features provides a notable improvement in the temporal analysis of EGFR endocytosis. Moreover, it is shown that the addition of the wavelet-based texture features contributes to this improvement. Our workflow can be applied to drug discovery to analyze defected EGFR endocytosis processes.

Shukla D.R.,Biomechanics Laboratory | Fitzsimmons J.S.,Biomechanics Laboratory | An K.-N.,Biomechanics Laboratory | O'Driscoll S.W.,Biomechanics Laboratory
Journal of Shoulder and Elbow Surgery | Year: 2012

Background: Radial head prosthetic stems designed for bone ingrowth are available with both plasma spray and grit blasted surfaces. A recent study comparing micromotion between the 2 demonstrated greater micromotion in the plasma spray than grit blasted stems, even though the latter had lower surface roughness. This raised the question that perhaps the size mismatch for grit-blasted radial head stems (0.5 mm) might be inadequate for plasma spray stems. Hypothesis: A tighter initial press-fit with plasma spray radial head stems may be gained by preparation with an undersized rasp. Methods: Paired cadaveric radii were implanted with plasma spray stems. The surgical control was prepared with a rasp designated for its corresponding stem size (" size-matched"), while the experimental group was prepared with a rasp 0.5 mm smaller than designated (" undersized"). Results: The micromotion for the undersized rasp group (46 ± 12 μm) was not significantly different than for the size-matched rasp group (21 ± 12 μm) (P = .1). Discussion: Contrary to our hypothesis, no reduction in micromotion was observed when using an undersized rasp with a plasma spray stem. The micromotion results were not different from those observed when using a size-matched rasp, and actually approached significance in the opposite direction. This may be due to the rough stem surface chipping away bone fragments, rather than the bone being cut away precisely as is done with a rasp. Conclusion: The use of an undersized rasp prior to implantation of a plasma spray radial head prosthesis does not confer any added benefit in terms of initial stability. © 2012 Journal of Shoulder and Elbow Surgery Board of Trustees.

Braidot A.A.A.,Biomechanics Laboratory | Aleman G.L.,Biomechanics Laboratory
Journal of Physics: Conference Series | Year: 2011

In this paper we designed and developed a mechanical device for gait rehabilitation based on the application of "partial body weight reduction therapy". An evaluation of the characteristics of devices based on this therapy currently available on the market was carried out obtaining information of the different mechanisms used in it. The device was designed to adapt to different height and weight of patients and to be used with additional equipment in gait rehabilitation, for example, treadmills, elliptical trainers and vertical scalers. It was envisaged to be used by patients with asymmetry in the lower extremities capabilities. We developed a stable structure in steel ASTM A36 which does not depend on the building conditions of the installation site. RamAdvanse software was used to calculate structural stability. A winch with automatic brake mechanism was used to raise/lower the patient, who was tied to a comfortable harness which provided safety to the patient and therapist. It was possible to quantify precisely, using counterweights, the weight borne by the patient during therapy. We obtained a small-sized and ergonomic low-cost prototype, with similar features to those currently considered cutting-edge devices.

Cantwell M.L.,Biomechanics Laboratory | Amirouche F.,Biomechanics Laboratory | Citerin J.,Biomechanics Laboratory
Sensors and Actuators, A: Physical | Year: 2011

A fully integrated low cost micropump is presented, including actuation, valving, electronics, sensing and control. The unique architecture and electromagnetic pumping technology enables contactless sensing and actuation, which makes it possible to separate the pumping mechanism from the electronic and actuation components. All pump components have been fabricated using conventional techniques to reduce production costs and address its alternative objective for disposable use. The proposed micropump is capable of delivering very high flow rates (170 mL/min) and features closed-loop control for therapies requiring a precise volumetric dosage. © 2011 Elsevier B.V. All rights reserved.

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