Changes in co-contraction magnitude during functional tasks following anterior cruciate ligament reconstruction: A systematic review.

BACKGROUND: Anterior cruciate ligament reconstruction (ACLR) is a common orthopedic surgery procedure whose incidence has increased over the past few decades. Nevertheless, it is believed that neuromuscular control remains altered from the early stages after ACLR to later years. Therefore, the aim of this study was to systematically evaluate the magnitude of co-contraction during functional tasks in subjects with unilateral ACLR. METHODS: A systematic review design was followed. The search strategy was conducted in PubMed, Scopus, EBSCO, PEDro, Cochrane Library, and Web of Science databases from inception to March 2024. The inclusion criteria involved studies using electromyography (EMG) data to calculate muscle pair activation via the co-contraction index (CCI) in ACLR individuals during functional tasks. The Preferred Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines were followed, and study quality was evaluated using National Institutes of Health (NIH) Study Quality Assessment Tools. RESULTS: The search strategy found a total of 792 studies, of which 15 were included in this systematic review after reviewing the eligibility criteria. The magnitude of co-contraction was assessed in a total of 433 ACLR individuals and 206 controls during functional tasks such as hop, drop-land, step-up/step-down, and gait. Overall, approximately 79.6% of individuals who had undergone ACLR exhibited increased levels of co-contraction magnitude in the ACLR limb, while 8.5% showed low co-contraction levels. CONCLUSIONS: The findings of the review suggest that, during functional tasks, most individuals who have undergone ACLR exhibit changes of co-contraction magnitude in the involved limb.

Short-Term Effects of Global Pelvic Manipulation on Knee Joint Position Sense in Asymptomatic Participants: A Double-Blind Randomized Controlled Trial.

OBJECTIVE: The purpose of this study was to evaluate short-term effects of the global pelvic manipulation (GPM) on knee joint position sense (JPS). METHODS: This randomized, controlled double-blind trial included 26 asymptomatic participants (X¯± 25.3; standard deviation ± 4.4 years) who were randomly allocated into 2 groups. Sixteen participants were allocated into the experimental group, in which GPM was performed, and the rest of the participants (n = 10) were included in the control group, which received sham ultrasound therapy. Each participant attended 1 session only, and the evaluations were assessed pretreatment and 5 minutes posttreatment through an isokinetic dynamometer (Biodex Medical Systems), in which the data regarding knee JPS ipsilateral to the manipulated sacroiliac joint were collected. Mann-Whitney and Wilcoxon tests were used, with a 95% significance level. RESULTS: There were no statistically significant differences between the groups concerning active and passive JPS at 30° and 60° (P > .05). The results showed a lack of significant differences between the moments in both groups (P > .05). CONCLUSION: This investigation demonstrated that GPM, with high-velocity low-amplitude thrust, has no effect on knee JPS, suggesting that this manipulative technique does not have a relative effect on muscle spindles and Golgi tendon organ activation in asymptomatic participants.

Exploring the nature of the interactions between the molecules of the sodium dodecyl sulfate and water in crystal phases and in the water/vacuum interface.

The nature of the interaction between the molecules of the sodium dodecyl sulfate surfactant forming two crystal phases, one anhydrous, NaC12H25O4S and the other, NaC12H25O4S.H2O, hydrated with one water molecule for unit cell, has been studied in detail using the quantum theory of atoms in molecules and a localized electron detector function. It was found that for the anhydrous crystal, the head groups of the surfactant molecules are linked into a head-to-head pattern, by a bond path network of Na-O ionic bonds, where each Na+ atom is attached to four S O 4 - groups. For the hydrated crystal, in addition to these four bonds for Na+, two additional ones appear with the oxygen atoms of the water molecules, forming a bond paths network of ionic Na-O bonds, that link the Na+ atoms with the S O 4 - groups and the H2O molecules. Each H2O molecule is bonded to two S O 4 - groups via hydrogen bonds, while the S O 4 - groups are linked to a maximum of four Na+ atoms. The phenomenon of aggregation of the sodium dodecyl sulfate molecules at the liquid water/vacuum interface was studied using NVT molecular dynamics simulations. We have found that for surfactant aggregates, the Na+ ions are linked to a maximum of three SO4 - groups and three water molecules that form Na-O bonds. Unlike hydrated crystal, each of the O atoms that make these Na-O bonds is linked to only one Na+ ion. Despite these differences, like the crystal phases, the surfactant molecules tend to form a head-to-head network pattern of ionic Na-O bonds that link their heads. The present results indicate that the clustering of anionic surfactant at the water/vacuum interface is a consequence of the electrostatic alignment of the cationic and anionic groups as occurs in the crystalline phases of sodium dodecyl sulfate.

Dynamics of Surfactant Clustering at Interfaces and Its Influence on the Interfacial Tension: Atomistic Simulation of a Sodium Hexadecane-Benzene Sulfonate-Tetradecane-Water System.

The process of equilibration of the tetradecane-water interface in the presence of sodium hexadecane-benzene sulfonate is studied using intensive atomistic molecular dynamics simulations. Starting as an initial point with all of the surfactants at the interface, it is obtained that the equilibration time of the interface (several microseconds) is orders of magnitude higher than previously reported simulated times. There is strong evidence that this slow equilibration process is due to the aggregation of surfactants molecules on the interface. To determine this fact, temporal evolution of interfacial tension and interfacial formation energy are studied and their temporal variations are correlated with cluster formation. To study cluster evolution, the mean cluster size and the probability that a molecule of surfactant chosen at random is free are obtained as a function of time. Cluster size distribution is estimated, and it is observed that some of the molecules remain free, whereas the rest agglomerate. Additionally, the temporal evolution of the interfacial thickness and the structure of the surfactant molecules on the interface are studied. It is observed how this structure depends on whether the molecules agglomerate or not.

On the electron density localization in elemental cubic ceramic and FCC transition metals by means of a localized electrons detector.

The electron density localization in insulator and semiconductor elemental cubic materials with diamond structure, carbon, silicon, germanium, and tin, and good metallic conductors with face centered cubic structure such as α-Co, Ni, Cu, Rh, Pd, Ag, Ir, Pt, and Au, was studied using a localized electrons detector defined in the local moment representation. Our results clearly show an opposite pattern of the electron density localization for the cubic ceramic and transition metal materials. It was found that, for the elemental ceramic materials, the zone of low electron localization is very small and is mainly localized on the atomic basin edges. On the contrary, for the transition metals, there are low-valued localized electrons detector isocontours defining a zone of highly delocalized electrons that extends throughout the material. We have found that the best conductors are those in which the electron density at this low-value zone is the lowest.

Charts for fetal age assessment based on fetal sonographic biometry in a population from Cali, Colombia.

OBJECTIVES: To create reference charts for fetal age assessment based on fetal sonographic biometry in a population of pregnant women living in the third largest city in Colombia and compare them with charts included in ultrasound machines. METHODS: The study data were obtained from women with a single pregnancy and confirmed gestational age between 12 and 40 completed weeks. All women were recruited specifically for the study, and every fetus was measured only once for biparietal diameter, head circumference, abdominal circumference, and femur length. Polynomial regression models for gestational age as a function of each fetal measurement were fitted to estimate the mean and standard deviation. Percentile curves of gestational age were constructed for each fetal measurement using these regression models. RESULTS: Biparietal diameter, head circumference, abdominal circumference, and femur length were measured in 792 fetuses. Tables and charts of gestational age were derived for each fetal parameter. A cubic polynomial model was the best-fitted regression model to describe the relationships between gestational age and each fetal measurement. The standard deviation was estimated by simple linear regression as a function of each fetal measurement. Comparison of our gestational age mean z scores with those calculated by reference equations showed statistically significant differences (P < .01). CONCLUSIONS: We present a set of reference charts, tables, and formulas for fetal age assessment based on fetal sonographic biometry. The results support the recommendation that these charts and tables could be more appropriate for assessing fetal age in Colombian populations than those currently included in the software of ultrasound machines.

Fetal size charts for a population from Cali, Colombia: sonographic measurements of biparietal diameter, head circumference, abdominal circumference, and femur length.

OBJECTIVES: To create reference charts for fetal sonographic biometric measurements in a population of pregnant women living in the third largest city in Colombia and compare them with charts included in ultrasound machines. METHODS: The data were obtained from women with a single pregnancy and confirmed gestational (menstrual) age between 12 and 40 weeks. All women were recruited specifically for the study, and every fetus was measured only once for biparietal diameter, head circumference, abdominal circumference, and femur length. Raw data for each fetal measurement were modeled by fitting regression models separately to estimate the mean and standard deviation as a function of gestational age. Percentile curves were constructed for each measurement by gestational age using these two regression models. We compared our mean z scores with those expected by reference equations. RESULTS: Measurements were obtained for 792 fetuses. A cubic polynomial model was the best-fitted regression model to describe the relationships between each fetal measurement and gestational age. The standard deviation for each measurement was estimated by simple linear regression as a function of gestational age. Comparison of our mean z scores with those by reference equations showed significant differences in some fetal measurements (P < .01). CONCLUSIONS: We present a set of reference percentile charts, tables, and formulas for fetal biometric measurements from a Colombian population. We believe that our fetal charts could be used nationwide in Colombia; nevertheless, a national sample will contribute to their validation and promotion of the development of Colombian fetal size charts.

Reverse buoyancy in a vibrated granular bed: Computer simulations.

We have performed molecular dynamics simulations of an intruder in a vibrated granular bed including interstitial fluid effects to account for the phenomenon of reverse buoyancy. We show that our model is able to reproduce the overall behaviour observed by previous experimental works and is the first finite-elements simulation to show the sinking of intruders lighter than the granular bed. To further advance our comprehension of this phenomenon, we studied the motion of the intruders in a single vibration cycle with respect to the bottom of the granular column, finding a substantial qualitative difference for heavy and light intruders and we compare these results with experiments using fine-sized glass beads. We show that, though heavy intruders seem unaffected by the force due to the fluid, the effect on light intruders is remarkable.