scholarly journals Biomechanical Models of the Hip – a Validation Study Based on 10 CT-Datasets

10.29007/rxxb ◽  
2018 ◽  
Author(s):  
Jörg Eschweiler ◽  
Malte Asseln ◽  
Philipp Damm ◽  
Maximilian C.M Fischer ◽  
Klaus Radermacher
Keyword(s):  
Hip Joint ◽  
Long Term Results ◽  
Patient Specific ◽  
Anatomical Landmarks ◽  
Joint Mechanics ◽  
X Ray ◽  
Biomechanical Models ◽  
In Vivo Measurements ◽  
The Impact

Consideration of the pre- and post-operative magnitude of the hip joint force R and its orientation Ɵ is of major importance for satisfactory long-term results in total hip arthroplasty. R and Ɵ can be computed by using biomechanical models with adapted geometrical/ anthropometrical parameters taken from clinical X-ray images. The objective of this study was to evaluate the models of Pauwels and Debrunner based on digital reconstructed-radiographs (central projection) from 10 CT-datasets of patients treated with telemetric hip-implants by a comparison to corresponding in-vivo measurements.R and Ɵ were computed for 10 patients with patient-specific geometric/anthropometric parameters. The model adaption was based on 28 anatomical landmarks. The root-mean-square-error of R is smaller for Debrunner (0.59/vs./0.66), and for Ɵ it is smaller for Pauwels’ (4.47/vs./7.78).Mathematical models provide potentially valuable information regarding hip joint mechanics. Regarding R, in all of the 10 patients the predictions of Pauwels’ model are consistently higher than the in-vivo measurements. Debrunner computed R in 8 cases higher and in 2 cases lower than the corresponding in-vivo forces. Pauwels’ and Debrunner showed similar tendencies: in 8 cases an overestimation of R and in 2 cases contrary results. Regarding Ɵ we found that in 5 cases the predictions of Pauwels’ are consistently higher than the in-vivo measurements and also contrary to Debrunner.As previous studies showed, an unambiguous identification of most landmarks in a 2D X-ray image is difficult. The impact of the pelvic tilt on the computational result was not considered in our study. Further investigation of this aspect is part of our ongoing work.

scholarly journals Deep Dive Into the Effects of Food Processing on Limiting Starch Digestibility and Lowering the Glycemic Response

Nutrients ◽  
2021 ◽  
Vol 13 (2) ◽  
pp. 381
Author(s):  
Gautier Cesbron-Lavau ◽  
Aurélie Goux ◽  
Fiona Atkinson ◽  
Alexandra Meynier ◽  
Sophie Vinoy
Keyword(s):  
Food Processing ◽  
Imaging Techniques ◽  
Food Products ◽  
International Standards ◽  
Starch Digestibility ◽  
Deep Dive ◽  
Processing Technologies ◽  
X Ray ◽  
The Impact

During processing of cereal-based food products, starch undergoes dramatic changes. The objective of this work was to evaluate the impact of food processing on the starch digestibility profile of cereal-based foods using advanced imaging techniques, and to determine the effect of preserving starch in its native, slowly digestible form on its in vivo metabolic fate. Four different food products using different processing technologies were evaluated: extruded products, rusks, soft-baked cakes, and rotary-molded biscuits. Imaging techniques (X-ray diffraction, micro-X-ray microtomography, and electronic microscopy) were used to investigate changes in slowly digestible starch (SDS) structure that occurred during these different food processing technologies. For in vivo evaluation, International Standards for glycemic index (GI) methodology were applied on 12 healthy subjects. Rotary molding preserved starch in its intact form and resulted in the highest SDS content (28 g/100 g) and a significantly lower glycemic and insulinemic response, while the three other technologies resulted in SDS contents below 3 g/100 g. These low SDS values were due to greater disruption of the starch structure, which translated to a shift from a crystalline structure to an amorphous one. Modulation of postprandial glycemia, through starch digestibility modulation, is a meaningful target for the prevention of metabolic diseases.

Numerical simulation of humidification and heating during inspiration within an adult nose

2012 ◽  
Vol 50 (2) ◽  
pp. 157-164
Author(s):  
F. Sommer ◽  
R. Kroger ◽  
J. Lindemann
Keyword(s):  
Numerical Simulations ◽  
High Speed ◽  
Middle Turbinate ◽  
Multislice Ct ◽  
Respiratory Cycle ◽  
In Vivo Measurements ◽  
Airflow Distribution ◽  
The Impact ◽  
Human Nose

Background: The temperature of inhaled air is highly relevant for the humidification process. Narrow anatomical conditions limit possibilities for in vivo measurements. Numerical simulations offer a great potential to examine the function of the human nose. Objective: In the present study, the nasal humidification of inhaled air was simulated simultaneously with temperature distribution during a respiratory cycle. Methods: A realistic nose model based on a multislice CT scan was created. The simulation was performed by the Software Fluent(r). Boundary conditions were based on previous in vivo measurements. Inhaled air had a temperature of 20(deg)C and relative humidity of 30%. The wall temperature was assumed to be variable from 34(deg)C to 30(deg)C with constant humidity saturation of 100% during the respiratory cycle. Results: A substantial increase in temperature and humidity can be observed after passing the nasal valve area. Areas with high speed air flow, e.g. the space around the turbinates, show an intensive humidification and heating potential. Inspired air reaches 95% humidity and 28(deg)C within the nasopharynx. Conclusion: The human nose features an enormous humidification and heating capability. Warming and humidification are dependent on each other and show a similar spacial pattern. Concerning the climatisation function, the middle turbinate is of high importance. In contrast to in vivo measurements, numerical simulations can explore the impact of airflow distribution on nasal air conditioning. They are an effective method to investigate nasal pathologies and impacts of surgical procedures.

Patient-specific simulation of a gallbladder refilling based on MRI and ultrasound in vivo measurements

2020 ◽  
Author(s):  
Aleksey G. Kuchumov ◽  
Marat R. Kamaltdinov ◽  
Vladimir A. Samartsev ◽  
Aleksander R. Khairulin ◽  
Yulia A. Ivashova ◽  
...  
Keyword(s):  
Patient Specific ◽  
In Vivo Measurements

IN VIVO MEASUREMENTS OF THE FRICTION MOMENT IN TOTAL HIP JOINT PROSTHESES DURING WALKING

2012 ◽  
Vol 45 ◽  
pp. S268 ◽  
Author(s):  
Philipp Damm ◽  
Robert Ackermann ◽  
Alwina Bender ◽  
Friedmar Graichen ◽  
Georg Bergmann
Keyword(s):  
Hip Joint ◽  
Total Hip ◽  
In Vivo Measurements ◽  
Friction Moment ◽  
Joint Prostheses

scholarly journals In vivo protein crystallization in living insect cells

2014 ◽  
Vol 70 (a1) ◽  
pp. C343-C343
Author(s):  
Lars Redecke ◽  
Marco Klinge ◽  
Robert Schönherr ◽  
Dirk Rehders ◽  
Dominik Oberthür ◽  
...  
Keyword(s):  
Crystal Growth ◽  
Structural Biology ◽  
Insect Cells ◽  
Protein Crystallization ◽  
Living Cells ◽  
Cellular Transport ◽  
Synchrotron Source ◽  
X Ray ◽  
The Impact

Spontaneous protein crystallization within living cells has been observed several times in nature, e.g. for storage proteins in seeds. In vivo crystal growth can also occur during gene over-expression, as particularly discovered in baculovirus-infected insect cells [1]. We have recently shown that these in vivo crystals represent valuable targets for structural biology after isolation from the cell. Applying serial crystallography techniques at an X-ray free-electron laser (XFEL) as well as using a highly brilliant synchrotron source, single crystal diffraction pattern were collected and combined to yield high-resolution structural information of the associated fully glycosylated protein [2,3]. So far, the cellular mechanisms involved in the in vivo crystallization process remain to be understood, preventing a more successful application of this novel approach. Thus, our study aims at identifying the parameters crucial for optimal crystal growth within baculovirus-infected Sf9 insect cells. Combining confocal microscopy with live-cell imaging techniques and compartment-specific staining methods, we systematically investigated the impact of the intracellular environment on in vivo crystallization by directing recombinant proteins into different cellular compartments using specific signal sequences. Moreover, the impact of cellular transport mechanisms and induced cellular stress on the quality and size of the in vivo crystals was investigated in detail. The presented results provide important insights into the process of protein crystallization within living cells and will therefore significantly contribute to increase the success rate for spontaneous crystal growth of other proteins. Considering that in vivo crystals represent highly suitable targets for structural biology, this approach offers exciting new possibilities for proteins that do not form crystals suitable for conventional X-ray diffraction in vitro.

scholarly journals In vivo visualization of pig vagus nerve ‘vagotopy’ using ultrasound

2020 ◽  
Author(s):  
Megan L. Settell ◽  
Maisha Kasole ◽  
Aaron C. Skubal ◽  
Bruce E. Knudsen ◽  
Evan N. Nicolai ◽  
...  
Keyword(s):  
Vagus Nerve ◽  
Motor Nerve ◽  
Nerve Fibers ◽  
Patient Specific ◽  
Neck Muscle ◽  
Therapeutic Effects ◽  
Ultrasound Images ◽  
Anatomical Landmarks ◽  
Novel Approach

AbstractBackgroundPlacement of the clinical vagus nerve stimulating cuff is a standard surgical procedure based on anatomical landmarks, with limited patient specificity in terms of fascicular organization or vagal anatomy. As such, the therapeutic effects are generally limited by unwanted side effects of neck muscle contractions, demonstrated by previous studies to result from stimulation of 1) motor fibers near the cuff in the superior laryngeal and 2) motor fibers within the cuff projecting to the recurrent laryngeal.ObjectiveThe use of patient-specific visualization of vagus nerve fascicular organization could better inform clinical cuff placement and improve clinical outcomes.MethodsThe viability of ultrasound, with the transducer in the surgical pocket, to visualize vagus nerve fascicular organization (i.e. vagotopy) was characterized in a pig model. Ultrasound images were matched to post-mortem histology to confirm the utility of ultrasound in identifying fascicular organization.ResultsHigh-resolution ultrasound accurately depicted the vagotopy of the pig vagus nerve intra-operatively, as confirmed via histology. The stereotypical pseudo-unipolar cell body aggregation at the nodose ganglion was identifiable, and these sensory afferent fascicular bundles were traced down the length of the vagus nerve. Additionally, the superior and recurrent laryngeal nerves were identified via ultrasound.ConclusionsIntraoperative visualization of vagotopy and surrounding nerves using ultrasound is a novel approach to optimize stimulating cuff placement, avoid unwanted activation of motor nerve fibers implicated in off-target effects, and seed patient-specific models of vagal fiber activation to improve patient outcomes.

Development and Evaluation of a Subject-Specific Lower Limb Model With an Eleven-Degrees-of-Freedom Natural Knee Model Using Magnetic Resonance and Biplanar X-Ray Imaging During a Quasi-Static Lunge

2020 ◽  
Vol 142 (6) ◽  
Author(s):  
David Leandro Dejtiar ◽  
Christine Mary Dzialo ◽  
Peter Heide Pedersen ◽  
Kenneth Krogh Jensen ◽  
Martin Kokholm Fleron ◽  
...  
Keyword(s):  
Magnetic Resonance ◽  
Knee Joint ◽  
Joint Model ◽  
Joint Kinematics ◽  
Contact Forces ◽  
Joint Mechanics ◽  
X Ray ◽  
Knee Mechanics ◽  
Subject Specific

Abstract Musculoskeletal (MS) models can be used to study the muscle, ligament, and joint mechanics of natural knees. However, models that both capture subject-specific geometry and contain a detailed joint model do not currently exist. This study aims to first develop magnetic resonance image (MRI)-based subject-specific models with a detailed natural knee joint capable of simultaneously estimating in vivo ligament, muscle, tibiofemoral (TF), and patellofemoral (PF) joint contact forces and secondary joint kinematics. Then, to evaluate the models, the predicted secondary joint kinematics were compared to in vivo joint kinematics extracted from biplanar X-ray images (acquired using slot scanning technology) during a quasi-static lunge. To construct the models, bone, ligament, and cartilage structures were segmented from MRI scans of four subjects. The models were then used to simulate lunges based on motion capture and force place data. Accurate estimates of TF secondary joint kinematics and PF translations were found: translations were predicted with a mean difference (MD) and standard error (SE) of 2.13 ± 0.22 mm between all trials and measures, while rotations had a MD ± SE of 8.57 ± 0.63 deg. Ligament and contact forces were also reported. The presented modeling workflow and the resulting knee joint model have potential to aid in the understanding of subject-specific biomechanics and simulating the effects of surgical treatment and/or external devices on functional knee mechanics on an individual level.

Capturing Three-Dimensional In Vivo Lumbar Intervertebral Joint Kinematics Using Dynamic Stereo-X-Ray Imaging

2013 ◽  
Vol 136 (1) ◽  
Author(s):  
Ameet K. Aiyangar ◽  
Liying Zheng ◽  
Scott Tashman ◽  
William J. Anderst ◽  
Xudong Zhang
Keyword(s):  
Lumbar Spine ◽  
Three Dimensional ◽  
Lumbar Vertebrae ◽  
Lumbar Vertebra ◽  
Weight Lifting ◽  
Data Set ◽  
X Ray ◽  
Biomechanical Models ◽  
Lifting Task

Availability of accurate three-dimensional (3D) kinematics of lumbar vertebrae is necessary to understand normal and pathological biomechanics of the lumbar spine. Due to the technical challenges of imaging the lumbar spine motion in vivo, it has been difficult to obtain comprehensive, 3D lumbar kinematics during dynamic functional tasks. The present study demonstrates a recently developed technique to acquire true 3D lumbar vertebral kinematics, in vivo, during a functional load-lifting task. The technique uses a high-speed dynamic stereo-radiography (DSX) system coupled with a volumetric model-based bone tracking procedure. Eight asymptomatic male participants performed weight-lifting tasks, while dynamic X-ray images of their lumbar spines were acquired at 30 fps. A custom-designed radiation attenuator reduced the radiation white-out effect and enhanced the image quality. High resolution CT scans of participants' lumbar spines were obtained to create 3D bone models, which were used to track the X-ray images via a volumetric bone tracking procedure. Continuous 3D intervertebral kinematics from the second lumbar vertebra (L2) to the sacrum (S1) were derived. Results revealed motions occurring simultaneously in all the segments. Differences in contributions to overall lumbar motion from individual segments, particularly L2–L3, L3–L4, and L4–L5, were not statistically significant. However, a reduced contribution from the L5–S1 segment was observed. Segmental extension was nominally linear in the middle range (20%–80%) of motion during the lifting task, but exhibited nonlinear behavior at the beginning and end of the motion. L5–S1 extension exhibited the greatest nonlinearity and variability across participants. Substantial AP translations occurred in all segments (5.0 ± 0.3 mm) and exhibited more scatter and deviation from a nominally linear path compared to segmental extension. Maximum out-of-plane rotations (<1.91 deg) and translations (<0.94 mm) were small compared to the dominant motion in the sagittal plane. The demonstrated success in capturing continuous 3D in vivo lumbar intervertebral kinematics during functional tasks affords the possibility to create a baseline data set for evaluating the lumbar spinal function. The technique can be used to address the gaps in knowledge of lumbar kinematics, to improve the accuracy of the kinematic input into biomechanical models, and to support development of new disk replacement designs more closely replicating the natural lumbar biomechanics.

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