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Background and Aim: Human knee joints experience very large loads and motions during regular daily, occupational and sport activities. Consequently, they are at high risk of being exposed to injuries and degeneration. Osteoarthritis and ligament injuries often inflict knee joints causing considerable pain and loss of productivity involving thus significant human and economic costs. Hence, biomechanics of human knee joints has been the focus of many investigations with the primary aim to improve understanding of joint function in normal and perturbed conditions. The existing prevention and treatment programs have been based on such studies. Materials and Methods: Due to inherent costs, limitations, difficulties and ethical concerns associated with in vivo and in vitro cadaveric studies, finite element model studies have been developed as effective, powerful and complementary tools to investigate knee joint biomechanics subject to internal and external mechanical conditions affecting its normal function. Results: The advantage of finite element method in study of joint biomechanics lies in its robustness to incorporate complex 3D joint geometry, intricate boundary and loading conditions and materials with nonhomogeneous and nonlinear properties. Conclusion: This article reviews important model studies, presents their relevant results and discusses some of the promising future directions. [ABSTRACT FROM AUTHOR]

Background: Traditional assessment (e.g., checklists, videotaping) for surgical proficiency may lead to subjectivity and does not predict performance in the clinical setting. Hand motion analysis is evolving as an objective tool for grading technical dexterity; however, most devices accompany with technical limitations or discomfort. We purpose the use of flexible wearable sensors to evaluate the kinematics of surgical proficiency., Methods: Surgeons were recruited and performed a vascular anastomosis task in a single institution. A modified objective structured assessment of technical skills (mOSATS) was used for technical qualification. Flexible wearable sensors (BioStamp RCTM, mc10 Inc., Lexington, MA) were placed on the dorsum of the dominant hand (DH) and nondominant hand (nDH) to measure kinematic parameters: path length (T path ), mean (V mean ) and peak (V peak ) velocity, number of hand movements (N move ), ratio of DH to nDH movements (rMov), and time of task (tTask) and further compared with the mOSATS score., Results: Participants were categorized as experts (n = 12) and novices (n = 8) based on a cutoff mean mOSATS score. Significant differences for tTask (P = 0.02), rMov (P = 0.07), DH T path (P = 0.04), V mean (P = 0.07), V peak (P = 0.04), and nDH N move (P = 0.02) were in favor of the experts. Overall, mOSATS had significant correlation with tTask (r = -0.69, P = 0.001), N move of DH (r = -0.44, P = 0.047) and nDH (r = -0.66, P = 0.001), and rMov (r = 0.52, P = 0.017)., Conclusions: Hand motion analysis evaluated by flexible wearable sensors is feasible and informative. Experts utilize coordinated two-handed motion, whereas novices perform one-handed tasks in a hastily jerky manner. These tendencies create opportunity for improvement in surgical proficiency among trainees., (Copyright © 2021 Elsevier Inc. All rights reserved.)

Objective: To examine the effect of a nanocolloidal silver-based gel called SilvoGel (ChitoTech, Iran) versus eosin (prepared by Razi Hospital, Iran) among patients with immunobullous disease., Method: This blind, randomised controlled study was carried out on patients with pemphigus vulgaris who had hard-to-heal ulcers, divided into two equal-sized groups: one treatment group receiving the nanocolloidal silver-based gel and the control group receiving the conventional eosin., Results: A total of 32 patients participated in the study. In both the treatment and control groups, ulcer area, exudate and tissue type improved significantly (p<0.001 for all measures). A significantly higher rate of improvement in ulcer area was observed in the treatment group compared with the control group (p<0.001). Both patient and physician satisfaction were significantly higher in the treatment group compared with the control group (p=0.003 and p=0.01, respectively)., Conclusion: The results of this study indicate that use of the nanocolloidal silver-based gel for treating patients with immunobullous disease including pemphigus could potentially increase the rate and quality of wound healing.

Background: The aim of this study was to describe the applicability of the Society for Vascular Surgery (SVS) objective performance goals (OPGs) as a tool to evaluate results in the context of endovascular management of noncomplex and complex patients (i.e., end stage renal disease/history of prosthetic conduit) with chronic limb-threatening ischemia (CLTI)., Methods: Patients diagnosed with CLTI undergoing endovascular procedures from March 2016 to April 2017 were included, and medical records were examined. Patients were categorized as OPG risk (OPGR) and non-OPG risk (nOPGR) groups in accordance with the SVS performance criteria. We compared clinical events between the two groups and then further to the SVS OPGs. Thirty-day outcomes (safety) were major amputation (AMP), major adverse limb events (MALEs), and major adverse cardiovascular events (MACEs), and 1-year outcomes (efficacy) were limb salvage, MALE + 30-day perioperative death (MALE + POD), and survival. Mortality was demonstrated using Kaplan-Meier analysis., Results: A total of 72 patients were included (OPGR = 58.3% vs. nOPGR = 41.7%). Mean follow-up was 20 months (range, 1-40 months). Retrograde pedal access was used in 65.2% of patients. The overall AMP rate was 2.7% (OPGR = 4.7%, nOPGR = 0%, P = 0.225, vs. SVS OPG<3%), MALE was 4.1% (OPGR = 7.1%, nOPGR = 0%, P = 0.135, vs. SVS OPG<8%), and MACE was 6.9% (OPGR = 2.3%, nOPGR = 13.3%, P = 0.071, vs. SVS OPG<8%). The limb salvage was 90.3% (OPGR = 88%, nOPGR = 93.3%, P = 0.46, vs. SVS OPG>84%), MALE + POD was 76.4% (OPGR = 78.6%, nOPGR = 73.4%, P = 0.606, vs. SVS OPG>71%), and survival was 77.7% (OPGR = 83.3%, nOPGR = 70%, P = 0.18, vs. SVS OPG>80%)., Conclusions: The SVS OPGs set appropriate safety and efficacy standards as a bar for new technologies. In this series, endovascular therapy in all-comers exceeded the safety and efficacy endpoints proposed by the limited risk OPG panel., (Copyright © 2020 Elsevier Inc. All rights reserved.)

Background: Foot problems are prevalent in older adults, which may increase the risk and concern for falls. Ankle-foot orthoses (AFO) have been shown to be effective in the stabilization of lower extremities, but their long-term effectiveness in improving balance and their potential to encourage older adults to become more physically active are still debated., Objective: This randomized controlled trial investigated the effectiveness of daily use of a custom-made AFO on balance, fear of falling, and physical activity in older adults., Study Design: Forty-four older adults with concern about or at risk for falling were randomly allocated to either the control group (CG; 77.3% female, age 75.6 ± 6.5 years, BMI 29.3 ± 6.4) or the intervention group (IG; 63.6% female, age 73.7 ± 6.3 years, BMI = 27.8 ± 4.8). The IG received walking shoes and bilateral custom-made AFO. The CG received only walking shoes. At the baseline and 6-month follow-ups, balance and physical activity were assessed using validated wearable instrumentation and fear of falling was assessed using the Fall Efficacy Scale-International (FES-I). Adherence and acceptability toward wearing the AFO were assessed using self-reported questionnaires at the 6-month follow-up., Results: No significant between-group difference was observed at baseline (p = 0.144-0.882). Compared to baseline and the CG, hip, ankle, and center-of-mass (COM) sways were significantly reduced at the 6-month follow-up in the IG while standing with the feet together during the eyes-open condition (p = 0.005-0.040). Within the IG, the FES-I was reduced significantly (p = 0.036) and there was an increasing trend in the number of walking bouts with a medium effect size (d = 0.52, p = 0.440) compared to baseline. However, there were no significant changes in FES-I and physical activity measures in the CG (p = 0.122-0.894). The reduction in COM sway in the IG was moderately correlated with adherence (r = -0.484, p = 0.047) and strongly correlated with baseline COM sway (r = -0.903, p < 0.001)., Conclusion: Results suggest that bilateral custom-made AFO plus walking shoes is effective in improving balance compared to walking shoes alone, and it significantly reduces the fear of falling, with a nonsignificant but noticeable positive trend in physical activity, compared to baseline. The results also suggest that older adults with poor balance at baseline and higher daily adherence to using the AFO will gain more benefit from the AFO intervention., (The Author(s). Published by S. Karger AG, Basel.)

Motor functions are deteriorated by aging. Some conditions may magnify this deterioration. This study examined whether hemodialysis (HD) process would negatively impact gait and balance beyond diabetes condition among mid-age adults (48⁻64 years) and older adults (65+ years). One hundred and ninety-six subjects (age = 66.2 ± 9.1 years, body-mass-index = 30.1 ± 6.4 kg/m², female = 56%) in 5 groups were recruited: mid-age adults with diabetes undergoing HD (Mid-age HD+, n = 38) and without HD (Mid-age HD-, n = 40); older adults with diabetes undergoing HD (Older HD+, n = 36) and without HD (Older HD-, n = 37); and non-diabetic older adults (Older DM-, n = 45). Gait parameters (stride velocity, stride length, gait cycle time, and double support) and balance parameters (ankle, hip, and center of mass sways) were quantified using validated wearable platforms. Groups with diabetes had overall poorer gait and balance compared to the non-diabetic group ( p < 0.050). Among people with diabetes, HD+ had significantly worsened gait and balance when comparing to HD- (Cohen's effect size d = 0.63⁻2.32, p < 0.050). Between-group difference was more pronounced among older adults with the largest effect size observed for stride length ( d = 2.32, p < 0.001). Results suggested that deterioration in normalized gait speed among HD+ was negatively correlated with age ( r = -0.404, p < 0.001), while this correlation was diminished among HD-. Interestingly, results also suggested that poor gait among Older HD- is related to poor ankle stability, while no correlation was observed between poor ankle stability and poor gait among Older HD+. Using objective assessments, results confirmed that the presence of diabetes can deteriorate gait and balance, and this deterioration can be magnified by HD process. Among HD- people with diabetes, poor ankle stability described poor gait. However, among people with diabetes undergoing HD, age was a dominate factor describing poor gait irrespective of static balance. Results also suggested feasibility of using wearable platforms to quantify motor performance during routine dialysis clinic visit. These objective assessments may assist in identifying early deterioration in motor function, which in turn may promote timely intervention.

Frailty assessment is dependent on the availability of trained personnel and it is currently limited to clinic and supervised setting. The growing aging population has made it necessary to find phenotypes of frailty that can be measured in an unsupervised setting for translational application in continuous, remote, and in-place monitoring during daily living activity, such as walking. We analyzed gait performance of 161 older adults using a shin-worn inertial sensor to investigate the feasibility of developing a foot-worn sensor to assess frailty. Sensor-derived gait parameters were extracted and modeled to distinguish different frailty stages, including non-frail, pre-frail, and frail, as determined by Fried Criteria. An artificial neural network model was implemented to evaluate the accuracy of an algorithm using a proposed set of gait parameters in predicting frailty stages. Changes in discriminating power was compared between sensor data extracted from the left and right shin sensor. The aim was to investigate the feasibility of developing a foot-worn sensor to assess frailty. The results yielded a highly accurate model in predicting frailty stages, irrespective of sensor location. The independent predictors of frailty stages were propulsion duration and acceleration, heel-off and toe-off speed, mid stance and mid swing speed, and speed norm. The proposed model enables discriminating different frailty stages with area under curve ranging between 83.2⁻95.8%. Furthermore, results from the neural network suggest the potential of developing a single-shin worn sensor that would be ideal for unsupervised application and footwear integration for continuous monitoring during walking.

Objective: Current prophylactic protocols fail to prevent deep venous thrombosis (DVT) in a significant minority of patients, and it remains one of the leading causes of preventable death. We therefore quantified the efficacy of novel game-based exercises (exergaming) to augment femoral venous parameters relative to ankle movement and muscle flexion., Methods: Healthy volunteers were recruited to perform a series of ankle and foot exercises using a wireless foot sensor (LEGSys; BioSensics LLC, Watertown, Mass) to navigate a computer cursor sequentially on a screen to the center of 200 circular targets. A single ultrasound technician (W.A.M.) measured each patient's mean flow volume, peak flow velocity, mean flow velocity, and cross-sectional area of the right femoral vein at baseline and obtained immediate postexercise (PEX), 5-minute PEX, and 15-minute PEX measurements. Electromyography (EMG) was performed at baseline and during the exercise. Baseline demographics and medical and surgical comorbidities were also recorded. The primary end point was the difference between baseline and immediate PEX mean flow volume estimates. We secondarily explored the association of baseline characteristics and EMG measurements with femoral vein parameters., Results: Fifteen healthy subjects (53% male; 28.1 ± 4.6 years) completed the exergaming task within a mean of 4 minutes, 2 ± 21 seconds. Immediately after exercise, the femoral vein mean flow volume, mean velocity, and peak systolic velocity increased by 49%, 53%, and 48%, respectively (P < .02 for each). Mean flow volume and velocity remained significantly elevated 5 minutes after exercise (P < .04 for each). Plantar flexion and dorsiflexion velocities and EMG frequency and intensity were not significantly correlated with PEX mean flow volume estimates (P > .05). Subgroup analysis revealed that women (P < .01) and Hispanics (P < .01) exhibited significantly slower PEX responses. Subjects with the largest improvements in mean flow volume had lower peak plantar flexion velocities (P < .01)., Conclusions: Exergaming increases mean flow volume, mean flow velocity, and peak systolic velocity within the femoral vein by approximately 50% above baseline. Exergaming represents a novel and potentially attractive method of DVT prevention by augmenting femoral vein mean volume flow and capitalizing on biofeedback. Less forceful but more uniform contractions were found to be most effective at augmenting venous blood flow. Exergaming will require further validation in larger study bases, among patients at higher risk of DVT., (Copyright © 2017 Society for Vascular Surgery. Published by Elsevier Inc. All rights reserved.)

Objective: This study examined the impact of shoe closure on plantar thermal stress response (TSR), which is known to be a surrogate of shear stress and skin perfusion. It is aimed to explore potential impact of shoe closure on increasing risk factors associated with plantar ulcers in people with diabetic peripheral neuropathy (DPN)., Methods: Fifteen eligible subjects were enrolled. The left foot was used as a reference and fitted to a self-adjusted and habitual lace-tightening method by each subject. The right foot was used as a test closure and fitted into three lace closure conditions: loose, tight, and preset optimal closure (reel clutch, BOA technology). Thermal images were taken after 5 minutes of acclimatization (pre-trial) and immediately after 200 walking steps in each shoe closure condition (post-trial). TSR was calculated from the thermal images., Results: TSR was significantly higher in the test closure with loose (70.24%, P = .000) and tight (66.85%, P = .007) and lower (-206.53%, P = .000) in the preset optimal closure when compared to the reference closure. Only lace closure conditions affected TSR with no significant impact from age, BMI, and gender in our sample in a multivariable regression model., Conclusion: The results from this study suggest that shoelace closure technique can have a profound effect on TSR. It therefore stands to reason that optimal lace closure may have an impact in reducing risk of plantar ulcers in people with DPN. Interestingly, results revealed that even a self-adjusted lace closure may not be necessarily optimal and a preset closure setting like reel clutch might ultimately be recommended to minimize risk. Further study is warranted to confirm or refute these interesting results.

Skeletal muscle accumulates intramuscular fat through age and obesity. Muscle quality, a measure of muscle strength per unit size, decreases in these conditions. It is not clear how fat influences this loss in performance. Changes to structural parameters (e.g. fibre pennation and connective tissue properties) affect the muscle quality. This study investigated the mechanisms that lead to deterioration in muscle performance due to changes in intramuscular fat, pennation and aponeurosis stiffness. A finite-element model of the human gastrocnemius was developed as a fibre-reinforced composite biomaterial containing contractile fibres within the base material. The base-material properties were modified to include intramuscular fat in five different ways. All these models with fat generated lower fibre stress and muscle quality than their lean counterparts. This effect is due to the higher stiffness of the tissue in the fatty models. The fibre deformations influence their interactions with the aponeuroses, and these change with fatty inclusions. Muscles with more compliant aponeuroses generated lower forces. The muscle quality was further reduced for muscles with lower pennation. This study shows that whole-muscle force is dependent on its base-material properties and changes to the base material due to fatty inclusions result in reductions to force and muscle quality., (© 2015 The Author(s).)

Skeletal muscle can contain neuromuscular compartments that are spatially distinct regions that can receive relatively independent levels of activation. This study tested how the magnitude and direction of the force developed by a whole muscle would change when the muscle activity was regionalized within the muscle. A 3D finite element model of a muscle with its bounding aponeurosis was developed for the lateral gastrocnemius, and isometric contractions were simulated for a series of conditions with either a uniform activation pattern, or regionally distinct activation patterns: in all cases the mean activation from all fibers within the muscle reached 10%. The models showed emergent features of the fiber geometry that matched physiological characteristics: with fibers shortening, rotating to greater pennation, adopting curved trajectories in 3D and changes in the thickness and width of the muscle belly. Simulations were repeated for muscle with compliant, normal and stiff aponeurosis and the aponeurosis stiffness affected the changes to the fiber geometry and the resultant muscle force. Changing the regionalization of the activity resulted to changes in the magnitude, direction and center of the force vector from the whole muscle. Regionalizing the muscle activity resulted in greater muscle force than the simulation with uniform activity across the muscle belly. The study shows how the force from a muscle depends on the complex interactions between the muscle fibers and connective tissues and the region of muscle that is active.

The molecular structure (hydrogen bonding, bond distances and angles), dipole moment and vibrational spectroscopic data [vibrational frequencies, IR and vibrational circular dichroism (VCD)] of cyclobutanonecdots, three dots, centeredHX (X = F, Cl) complexes were calculated using density functional theory (DFT) and second order Møller-Plesset perturbation theory (MP2) with basis sets ranging from 6-311G, 6-311G(**), 6-311 + + G(**). The theoretical results are discussed mainly in terms of comparisons with available experimental data. For geometric data, good agreement between theory and experiment is obtained for the MP2 and B3LYP levels with basis sets including diffuse functions. Surface potential energy calculations were carried out with scanning HCl and HF near the oxygen atom. The nonlinear hydrogen bonds of 1.81 A and 175 degrees for HCl and 1.71 A and 161 degrees for HF were calculated. In these complexes the C=O and H-X bonds participating in the hydrogen bond are elongated, while others bonds are compressed. The calculated vibrational spectra were interpreted and the band assignments reported are in excellent agreement with experimental IR spectra. The C=O stretching vibrational frequencies of the complexes show red shifts with respect to cyclobutanone.

The low temperature magnetic circular dichroism (MCD) and electron paramagnetic resonance (EPR) spectra of Cu(II) doped Cs(2)ZrCl(6) are reported. The Cu(II) ion is incorporated as the square planar copper tetrachloride ion, CuCl(4) (2-), which substitutes at the Zr(IV) site in the Cs(2)ZrCl(6) lattice, with a complete absence of axial coordination. Both the EPR and MCD show highly resolved spectra from which it is possible to determine the superhyperfine coupling constants and excited state geometries respectively. The Franck-Condon intensity patterns suggest that there is a substantial relaxation of the host lattice about the impurity ion. For the lowest energy (2)B(1g)(x(2)-y(2))-->(2)B(2g)(xy) transition, both the magnetic dipole allowed electronic origin as well as vibronic false origins are observed. The high resolution of the spectra allowed the accurate determination of the odd parity vibrations that are active in the spectra. The opposite sign of the MCD of the two components of the (2)E(g)(xz,yz) excited state allows this splitting to be determined for the first time. Accurate and unambiguous spectral parameters for the CuCl(4) (2-) ion are important as it has become a benchmark transition metal complex for theoretical electronic structure calculations.

We simulated the knee arthrometry test to obtain a deeper understanding of the joint's stability behavior and interpret the arthrometric results more effectively. A 2D sagittal plane finite element model of the lower limb in the standard configuration of knee arthrometry was developed using ANSYS APDL. A detailed model of the knee joint was considered including the femoral articulating contour represented by an ellipse, the tibial plateau represented by a circular arc, and four major knee ligaments and their individual bundles represented by linear and nonlinear tensile springs. A deformable layer of articular cartilage was also considered over the tibial plateau to simulate the bones engagement more precisely. The model was analyzed while the tibia was subjected to an anterior drawer force of up to 150 N with 10 N increments and the tibial anterior translation was obtained. Simulation of the arthrometry test for different curvatures of the tibial plateau revealed that the bones engagement has a considerable effect on the knee joint's laxity. However, a considerable change from the intact knee's data curve was only observed when the ACL total ruptured was simulated. This emphasizes the difficult task involved when trying to distinguish the partial injuries of the ACL using arthrometric data.

Molecular structure and vibrational frequencies of 4,4,4-trifluoro-1-phenyl-1,3-butanedione, known as trifluorobenzoylacetone (TFBA), have been investigated by means of density functional theory (DFT) calculations. The results were compared with those of benzoylacetone (BA), acetylacetone (AA), and trifluoroacetylacetone (TFAA). Comparing the calculated and experimental band frequencies and intensities suggests coexisting of both stable cis-enol conformers in comparable proportions in the sample. The energy difference between the two stable chelated enol forms is negligible, 0.96 kcal/mol, calculated at B3LYP/6-311++G** level of theory. The molecular stability and the hydrogen bond strength were investigated by applying the natural bond orbital (NBO) theory and geometry calculations. The theoretical calculations and spectroscopic results indicate that the hydrogen bond strength of TFBA is between those of TFAA and AA, considerably weaker than that of BA.

Molecular structure and vibrational frequencies of triformylmethane have been investigated by means of density functional theory (DFT) calculations. The geometrical parameters and vibrational frequencies obtained in the B3LYP, B3PW91, BLYP, BPW91, G96LYP and G96PW91 levels of DFT and compared with the corresponding parameters of malonaldehyde (MA). Fourier transform infrared spectra of triformylmethane and its deuterated analogue were clearly assigned. Theoretical calculations show that the hydrogen bond strength of triformylmethane is stronger than that of MA, which is in agreement with spectroscopic results.

Molecular and vibrational structure of 1,1,1,6,6,6-hexafluoropentane-2,4-dione (hexafluoro-acetylacetone) have been investigated by means of density functional theory (DFT) calculations and have been compared with those of acetylacetone, the parent molecule. According to the theoretical calculations HFAA has an asymmetric structure with hydrogen bond strength of about 12 kcal mol(-1), about 6 kcal mol(-1) less than that of acetylacetone. This weakening of hydrogen bond is consistent with frequency shifts for OH/OD stretching, OH/OD out of plane bending and O...O stretching modes upon substitution of methyl hydrogen atoms with fluorine atoms. The symmetric structure based on electron diffraction data is interpreted as superposition of two asymmetric structures.