surface geometry
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The sacroiliac joint (SIJ) exhibits significant variation in auricular surface morphology. This variation influences the mechanics of the SIJ, a central node for transmitting mechanical energy from upper body to lower limbs and vice versa. The impact of the auricular surface morphology on stress and deformation in the SIJ remains poorly understood to date. Computed tomography scans obtained from 281 individuals were included to extract the geometry of the pelvic ring. Then, the auricular surface area, SIJ cartilage thickness, and total SIJ cartilage volume were identified. Based on these reconstructions, 281 finite element models were created to simulate SIJ mechanical loading. It was found that SIJ cartilage thickness only weakly depended on age or laterality, while being strongly sex sensitive. Auricular surface area and SIJ cartilage volume depended weakly and non-linearly on age, peaking around menopause in females, but without significant laterality effect. Larger SIJs, characterized by greater auricular area and cartilage volume, exhibited reduced stress and deformation under loading. These findings highlight the significant role of SIJ morphology in its biomechanical response, suggesting a potential link between morphological variations and the risk of SIJ dysfunction. Understanding this relationship could improve diagnosis and targeted treatment strategies for SIJ-related conditions.
- MeSH
- analýza metodou konečných prvků MeSH
- biomechanika fyziologie MeSH
- dospělí MeSH
- lidé středního věku MeSH
- lidé MeSH
- mechanický stres MeSH
- mladiství MeSH
- mladý dospělý MeSH
- počítačová rentgenová tomografie * MeSH
- sakroiliakální kloub * anatomie a histologie fyziologie diagnostické zobrazování MeSH
- senioři nad 80 let MeSH
- senioři MeSH
- Check Tag
- dospělí MeSH
- lidé středního věku MeSH
- lidé MeSH
- mladiství MeSH
- mladý dospělý MeSH
- mužské pohlaví MeSH
- senioři nad 80 let MeSH
- senioři MeSH
- ženské pohlaví MeSH
- Publikační typ
- časopisecké články MeSH
BACKGROUND: The acromion projects laterally in a curving orientation. When a fracture of the acromion occurs, despite being rare, matching the best-fit fixation plate is challenging due to few options and limited availability of fixation plate types. Alternative fixation methods can carry risk of nonunion complications. PURPOSE: The objective of this study was to investigate the morphological curvature pattern of the acromion to assess the level of the fixation plates fitness and provide the suitable imaging modalities for evaluating the acromion curvature. BASIC PROCEDURES: The correlation between the acromion curvature and five fixation plates were calculated and their fitness level was evaluated statistically. The curvature of acromion and the five available fixation plates were photographed and assessed digitally by software (FIJI ImageJ and Microsoft Excel). The method entails plotting seven points along the curving surface and margins of the acromion, while the Excel Solver function calculates the regression, ultimately giving curvature values. First, the acromion parameters were studied on 180 paired healthy dry scapulae. Then, the acromion curvature values were compared to the fixation plates curvatures. Likewise, the acromion curvature was assessed as applicable on 153 (100 AP- views, 50 Y- views, and 3 superior-views) retrospective plain X-rays and 40 3D-CT scapula reconstructions of healthy acromia. MAIN FINDINGS: The mean length of the acromion was 48.70 ± 5.29 mm, mean thickness was 8.51 ± 1.67 mm, and mean width was 25.97 ± 5.97 mm. The calculated values of the mean curvatures were 0.050 ± 0.015 mm-1 for the mean acromion surface, 0.042 ± 0.027 mm-1 for the internal margin, and 0.055 ± 0.010 mm-1 for the external margin. The curved geometry of the acromion was plotted on a graph giving a spectrum of curvature patterns with distribution values revealing fixation plates fitness represented by area under the curve with frequencies of 4.32 % for the acromion-specific fixation plate, 14.28 % for the large clavicle fixation plate, 0.26 % for the small clavicle fixation plate, 53.38 % for the flexible universal fixation plate, and none for the rigid universal fixation plate. PRINCIPAL CONCLUSIONS: Approximately 27.76 % of the acromion surface curvatures distribution does not overlap with any of our measured fixation plates. Evaluating the acromion surface curvature was possible on plain X-rays in the Y-view only.
- MeSH
- akromion * diagnostické zobrazování zranění anatomie a histologie chirurgie MeSH
- fraktury kostí * chirurgie diagnostické zobrazování MeSH
- kostní destičky * MeSH
- lidé MeSH
- lopatka * diagnostické zobrazování anatomie a histologie MeSH
- radiografie MeSH
- vnitřní fixace fraktury * metody přístrojové vybavení MeSH
- Check Tag
- lidé MeSH
- mužské pohlaví MeSH
- ženské pohlaví MeSH
- Publikační typ
- časopisecké články MeSH
Brachyterapie s vysokým dávkovým příkonem (high dose rate brachytherapy, HDR BRT) je dnes prováděna výhradně automatickými afterloadingovými ozařovači. Nejčastějšími jsou aplikace intrakavitární a intersticiální, případně jejich kombinace. Důležitým aspektem plánování intersticiální brachyterapie je spolupráce lékaře s fyzikem již ve fázi zavádění aplikátorů. Úprava geometrie zavedených aplikátorů v pozdější fázi již často není realizovatelná. Pro výpočet ozařovacích plánů brachyterapie lze využít řadu zobrazovacích modalit. V článku jsou shrnuty fyzikální parametry hodnocení kvality ozařovacích plánů a cíle jejich optimalizace.
High dose rate brachytherapy is realized solely by automatic afterloading irradiators nowadays. The most common are intracavitary and interstitial applications. Cooperation between a physician and a physicist before insertion of applicators is a very important aspect. Changes of applicators' geometry are usually not possible afterwards. A range of imaging modalities can be used for brachytherapy planning. A physical parameters useful for quality assessment and optimization of the plans are presented in this article.
- Klíčová slova
- afterloading,
- MeSH
- brachyterapie * metody přístrojové vybavení MeSH
- celková dávka radioterapie MeSH
- fyzikální jevy * MeSH
- lidé MeSH
- nádory diagnostické zobrazování radioterapie MeSH
- plánování radioterapie pomocí počítače metody přístrojové vybavení MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- přehledy MeSH
Development of the craniofacies occurs in embryological intimacy with development of the brain and both show normal left-right asymmetries. While facial dysmorphology occurs to excess in psychotic illness, facial asymmetry has yet to be investigated as a putative index of brain asymmetry. Ninety-three subjects (49 controls, 22 schizophrenia, 22 bipolar disorder) received 3D laser surface imaging of the face. On geometric morphometric analysis with (x, y, z) visualisations of statistical models for facial asymmetries, in controls the upper face and periorbital region, which share embryological intimacy with the forebrain, showed marked asymmetries. Their geometry included: along the x-axis, rightward asymmetry in its dorsal-medial aspects and leftward asymmetry in its ventral-lateral aspects; along the z-axis, anterior protrusion in its right ventral-lateral aspect. In both schizophrenia and bipolar disorder these normal facial asymmetries were diminished, with residual retention of asymmetries in bipolar disorder. This geometry of normal facial asymmetries shows commonalities with that of normal frontal lobe asymmetries. These findings indicate a trans-diagnostic process that involves loss of facial asymmetries in both schizophrenia and bipolar disorder. Embryologically, they implicate loss of face-brain asymmetries across gestational weeks 7-14 in processes that involve genes previously associated with risk for schizophrenia.
- MeSH
- asymetrie obličeje * diagnostické zobrazování patologie MeSH
- bipolární porucha * diagnostické zobrazování patologie MeSH
- dospělí MeSH
- funkční lateralita fyziologie MeSH
- lidé středního věku MeSH
- lidé MeSH
- mladý dospělý MeSH
- mozek diagnostické zobrazování patologie MeSH
- obličej MeSH
- psychotické poruchy diagnostické zobrazování patologie MeSH
- schizofrenie * diagnostické zobrazování patologie MeSH
- zobrazování trojrozměrné MeSH
- Check Tag
- dospělí MeSH
- lidé středního věku MeSH
- lidé MeSH
- mladý dospělý MeSH
- mužské pohlaví MeSH
- ženské pohlaví MeSH
- Publikační typ
- časopisecké články MeSH
Diffusion is a mass transport phenomenon caused by chaotic thermal movements of molecules. Studying the transport in specific domain is simplified by using evolutionary differential equations for local concentration of the molecules instead of complete information on molecular paths [1]. Compounds in a fluid mixture tend to smooth out its spatial concentration inhomogeneities by diffusion. Rate of the transport is proportional to the concentration gradient and coefficient of diffusion of the compound in ordinary diffusion. The evolving concentration profile c(x,t) is then solution of evolutionary partial differential equation deltac/deltat=DDeltac where D is diffusion coefficient and Delta is Laplacian operator. Domain of the equation may be a region in space, plane or line, a manifold, such as surface embedded in space, or a graph. The Laplacian operates on smooth functions defined on given domain. We can use models of diffusion for such diverse tasks as: a) design of method for precise measurement of receptors mobility in plasmatic membrane by confocal microscopy [2], b) evaluation of complex geometry of trabeculae in developing heart [3] to show that the conduction pathway within the embryonic ventricle is determined by geometry of the trabeculae.
BACKGROUND AND OBJECTIVE: The prevalence of pelvic floor muscle injuries induced by childbirth is higher than 23 % in the general women population. Such injuries can lead to prolapses and other pathologies in future female life. Leveraging computational biomechanics, the study implements an advanced female pelvic floor model for computing the maximum pelvic muscle strain, which serves as an injury risk indicator. The design of experiment method, abbreviated as DoE, is used to compute the maximum strain for boundary values of bony pelvis dimensions, namely the anterior-posterior diameter (abbreviated as APD) and the transverse diameter (abbreviated as TD). This is done in combination with small, medium and large percentiles of fetal head circumference (abbreviated as HC). METHODS: We utilized a previously developed finite element model of a female pelvic floor, as a reference, and enhanced it with new features, including a more detailed tissue geometry and advanced constitutive material models. The APD and TD dimensions were sourced from the set of MRI of 64 nulliparous women. This data was used to estimate the boundary dimensions of the female bony pelvis, combining both small and large values of APD and TD. Together with the 10th and the 95th percentiles for HC, a three-dimensional domain was constructed to assess the maximum pelvic muscle strain. In boundary cases, the maximum pelvic muscle strain was computed across 8 full-factorial design models (each situated at one corner of the domain, thereby combining the minimum and the maximum values of APD, TD and HC). This was done to define a response surface that predicts the maximum pelvic muscle strain within the domain. The accuracy of this response surface prediction was validated using 15 additional intermediate design models. These models were placed at the center of the domain (1 point), the centres of the domain boundary surfaces (6 points), and midway along each domain boundary edge (8 points). RESULTS: The maximum strain results for 8 combinations of APD, TD, and HC were employed to construct a linear response surface as a function of APD, TD, and HC. Tests at an additional 19 domain points served to evaluate the efficiency of the response surface prediction. The response surface demonstrated strong predictability, with an absolute average error of 1.52 %, an absolute median error of 1.52 %, and an absolute maximum error of 11.11 %. HC emerged as the most influencing dimension, accounting for 16 % of influence. CONCLUSIONS: The reference finite element pelvic floor model was scaled to 8 full-factorial female-specific pelvic floor models, which represent the combination of boundary values for APD, TD, and HC. The maximum pelvic floor muscle strain from these 8 models was used to design a response surface. When implementing the DoE approach to construct the response, there was consistent predictability for the maximum perineal muscle strain, as validated by the additional 19 intermediate design models. As a result, the response surface methodology can serve as an initial predictor for potential childbirth-induced pelvic floor muscle injury.
- MeSH
- kosterní svaly diagnostické zobrazování MeSH
- lidé MeSH
- magnetická rezonanční tomografie MeSH
- pánevní dno diagnostické zobrazování fyziologie MeSH
- porod * fyziologie MeSH
- těhotenství MeSH
- vedení porodu * MeSH
- Check Tag
- lidé MeSH
- těhotenství MeSH
- ženské pohlaví MeSH
- Publikační typ
- časopisecké články MeSH
PURPOSE OF THE STUDY To compare the treatment outcome of scaphoid facture fixation with one versus two Herbert screws (HBS). MATERIAL AND METHODS 72 patients underwent open reduction internal fixation (ORIF) following acute scaphoid fracture, and were followed prospectively by one surgeon. All fractures were Herbert & Fisher classification type B, the most common fracture lines being oblique (n=38) and transverse (n=34). Fractures with similar fracture lines were randomly assigned into two groups; fractures stabilized with one HBS (n=42) and fractures stabilized with two HBS (n=30). A specific methodology was developed for placement of two HBS; in the case of transverse fractures, screws were introduced perpendicular to the fracture line, for oblique fractures the first screw was placed perpendicular to the fracture line and the second screw was placed along the longitudinal axis of the scaphoid. RESULTS Patients were followed for a total 24 months, no patients were lost to follow-up. Outcome measures included bone healing, duration to bone healing, carpal geometry, range of motion (ROM), grip strength, and the Mayo Wrist Score. Patient rated outcomes were measured using DASH. Bone healing was radiographically and clinically confirmed in 70 patients. There were two non-unions after fixation with one HBS. Radiographic angles in both groups did not differ significantly from the physiological values. The mean duration to bone union was 1.8 months for one HBS and 1.5 months for two HBS. Mean grip strength was 47 kg in the group with one HBS (16-70 kg), 94 % of the unaffected hand, and 49 kg in the group with two HBS, 97% unaffected hand. The average Visual Analog Scale (VAS) score for the group with one HBS was 2.5, while for the group with two HBS was 2.0. Both groups had excellent and good results. For the group with two HBS, they are more. (100% for those fixed with two HBS and for those fixed with one HBS = 95% excellent and good and 5% bad results). DISCUSSION A review of the literature confirms that the addition of the second screw increases the stability in the scaphoid fractures by offering added resistance to torque forces. Most authors propose the parallel placing of both screws in all cases. In our study we offer an algorithm for the placement of screws depending of the type of fracture line. For transverse fractures screws are placed parallel and perpendicular to the fracture line, for oblique fractures the first screw is placed perpendicular to the fracture line, and the second screw is placed along the longitudinal axis of the scaphoid. This algorithm covers the main laboratory requirements for maximal fracture compression depending of the fracture line. CONCLUSIONS This study of 72 patients in whom patients with similar fracture geometry were separated into two groups fixed by one HBS and fixed by two HBS. Analysis of the results demonstrate that osteosynthesis with two HBS creates greater fracture stability. The proposed algorithm for fixation of acute scaphoid fractures using two HBS is achieved by simultaneously placing the screw along the axial axis and perpendicular to the fracture line. The stability is improved by the equal distribution of the compression force on the entire fracture surface. Key words: scaphoid fractures, Herbert screw, two screws fixation.
A new solution for local anesthetic and antibiotic delivery after eye surgery is presented. A contact lens-shaped collagen drug carrier was created and loaded by Levofloxacin and Tetracaine with a riboflavin crosslinked surface layer, thus impeding diffusion. The crosslinking was confirmed by Raman spectroscopy, whereas the drug release was investigated using UV-Vis spectrometry. Due to the surface barrier, the drug gradually releases into the corneal tissue. To test the function of the carrier, a 3D printed device and a new test method for a controlled drug release, which mimics the geometry and physiological lacrimation rate of the human eye, were developed. The experimental setup with simple geometry revealed that the prepared drug delivery device can provide the prolonged release profile of the pseudo-first-order for up to 72 h. The efficiency of the drug delivery was further demonstrated using a dead porcine cornea as a drug recipient, without the need to use live animals for testing. Our drug delivery system significantly surpasses the efficiency of antibiotic and anesthetic eyedrops that would have to be applied approximately 30 times per hour to achieve the same dose as that delivered continuously by our device.
- Publikační typ
- časopisecké články MeSH
Rhamnolipids (RMLs) are a widely studied biosurfactant due to their high biodegradability and environmentally friendly production. However, the knowledge of the structure-property relationship of RMLs is imperative for the design of highly efficient applications. Aiming to a better understanding of it at a molecular level, we performed an automated search for low energy structures of the most abundant RMLs, namely, Rha-C10 , Rha-C10 -C10 , Rha-Rha-C10 and Rha-Rha-C10 -C10 and their respective C2 -congeners. Besides that, selected neutral metal complexes were also considered. We found that several low-energy congeners have internal hydrogen bonds. Moreover, geometries in "closed" conformation were always more stable than "open" ones. Finally, the energy diferences between open and closed conformations of K+ , Ni2+ , Cu2+ and Zn2+ complexes were found to be 23.5 kcal mol-1 , 62.8 kcal mol-1 , 24.3 kcal mol-1 and 41.6 kcal mol-1 , respectively, indicating a huge structural reorganization after the complex formation.
- MeSH
- glykolipidy chemie MeSH
- povrchově aktivní látky * chemie MeSH
- Pseudomonas aeruginosa * MeSH
- Publikační typ
- časopisecké články MeSH
The spontaneous formation of chiral structures offers a variety of liquid crystals (LC) phases that could be further tailored for practical applications. In our work, the characteristic features of spiral ordering in the cholesteric phase of EZL10/10 LC were evaluated. To disclose resonant reflections related to a nanoscale helix pitch, resonant soft X-ray scattering at the carbon K edge was employed. The angular positions of the observed element-specific scattering peaks reveal a half-pitch of the spiral ordering p/2 ≈ 52 nm indicating the full pitch of about 104 nm at room temperature. The broadening of the peaks points to a presence of coherently scattering finite-size domains formed by cholesteric spirals with lengths of about five pitches. No scattering peaks were detectable in the EZL10/10 isotropic phase at higher temperatures. The characteristic lengths extracted from the resonant soft X-ray scattering experiment agree well with the periodicity of the surface "fingerprint" pattern observed in the EZL10/10 cholesteric phase by means of atomic force microscopy. The stability of LC molecules under the incident beam was proven by X-ray absorption spectroscopy in transmission geometry.
- Publikační typ
- časopisecké články MeSH
