Sitting Positions Research Articles

Effect of Patient Position during Spinal Anesthesia on the Incidence of Post-Dural Puncture Headache after Cesarean Section

Objective: To compare the incidence of post-dural puncture headache (PDPH) following spinal anesthesia in parturients undergoing elective cesarean section between the sitting and left lateral decubitus positions. Methodology: This quasi-experimental study was conducted at Holy Family Hospital, Rawalpindi, Pakistan, from May 2022 to October 2022. A total of 120 parturients undergoing elective cesarean section under spinal anesthesia were randomly assigned to either the sitting or left lateral decubitus position group. The primary outcome was the occurrence of PDPH within 5 days postoperatively. Secondary outcomes included adverse effects such as hypotension, nausea/vomiting, and bradycardia. Data were analyzed using SPSS version 25.0. Categorical variables were compared using the chi-square test or Fisher's exact test, as appropriate, with a significance level set at p < 0.05. Results: The incidence of PDPH post-procedure was significantly higher in the sitting group compared to the left lateral decubitus group (33.3% vs. 6.7%). In the sitting position group, 63.3% of women experienced hypotension, 26.7% had bradycardia, and 30.0% reported nausea/vomiting, whereas in the left lateral decubitus group, these figures were 58.3%, 21.7%, and 23.3%, respectively. Conclusion: This study concludes that the left lateral decubitus position during spinal anesthesia for cesarean section is associated with a lower incidence of PDPH compared to the sitting position.

Effects of Sitting and Supine Positions on Tongue Color as Measured by Tongue Image Analyzing System and Its Relation to Biometric Information.

Tongue diagnosis is one of the important diagnostic methods in Kampo (traditional Japanese) medicine, in which the color and shape of the tongue are used to determine the patient's constitution and systemic symptoms. Tongue diagnosis is performed with the patient in the sitting or supine positions; however, the differences in tongue color in these two different positions have not been analyzed. We developed tongue image analyzing system (TIAS), which can quantify tongue color by capturing tongue images in the sitting and supine positions. We analyzed the effects on tongue color in two different body positions. Tongue color was quantified as L∗a∗b∗ from tongue images of 18 patients in two different body positions by taking images with TIAS. The CIEDE 2000 color difference equation (ΔE00) was used to assess the difference in tongue color in two different body positions. Correlations were also determined between ΔE00, physical characteristics, and laboratory test values. The mean and median ΔE00 for 18 patients were 2.85 and 2.34, respectively. Of these patients, 77.8% had a ΔE00 < 4.1. A weak positive correlation was obtained between ΔE00 and systolic blood pressure and fasting plasma glucose. Approximately 80% of patients' tongue color did not change between the sitting and supine positions. This indicates that the diagnostic results of tongue color are trustworthy even if medical professionals perform tongue diagnosis in two different body positions.

A crosstalk-free interdigital electrode piezoresistive sensor matrix-based human-machine interaction system for automatic sitting posture recognition

Sedentarism with poor posture has been a significant concern for students and office workers. In this work, for inappropriate sitting posture monitoring, we developed a human machine interaction (HMI) system based on a piezoresistive sensor matrix, which achieves crosstalk-free pressure distribution detection by the inserting diodes method (IDM) with a structure simplified by the interdigital electrode (IDE) configuration. To measure the pressure distribution, a sensor matrix of 9×14 piezoresistive sensing pixels is fabricated by the standard flexible printed circuit (FPC) technique. The single sensing pixel shows a high sensitivity in the pressure below 20 kPa, covering the range of the human-seat contact pressure, and demonstrates the highest sensitivity of 9.865% kPa−1. The combination of the IDE and the IDM eliminates the crosstalk error completely, enabling the sensor matrix to accurately measure the human-chair contact pressure distribution. To develop an HMI system for sitting posture detection, pressure distribution data from subjects of different body shapes, including sitting upright, leaning forward, slumped sitting, crossing right legs, and crossing left legs, is collected using the proposed sensor matrix and used for training and evaluation of the convolution neural network (CNN) model. Accurate posture classification is achieved both in within-group and cross-group tests, showing the highest accuracy of 99.14% and an excellent generalization performance. With an excellent performance of crosstalk-free pressure distribution detection, the device in this study exhibits great application potential in daily sitting posture monitoring.

Highly Sensitive Iontronic Pressure Sensor with Side-by-Side Package Based on Alveoli and Arch Structure.

Flexible pressure sensors play a significant role in wearable devices and electronic skin. Iontronic pressure sensors with high sensitivity, wide measurement range, and high resolution can meet requirements. Based on the significant deformation characteristics of alveoli to improve compressibility, and the ability of the arch to disperse vertical pressure into horizontal thrust to increase contact area, a graded hollow ball arch (GHBA) microstructure is proposed, greatly improving sensitivity. The fabrication of GHBA ingeniously employs a double-sided structure. One side uses mold casting to create convex structures, while the other utilizes the evaporation of moisture during the curing process to form concave structures. At the same time, a novel side-by-side package structure is proposed, ensuring pressure on flexible substrate is maximally transferred to the GHBA microstructure. Within the range of 0.2Pa-300kPa, the iontronic pressure sensor achieves a maximum sensitivity of 10420.8kPa-1, pressure resolution of 0.1% under the pressure of 100kPa, and rapid response/recovery time of 40/35ms. In wearable devices, it is capable of monitoring dumbbell curl exercises and wirelessly correcting sitting positions. In electronic skin, it can non-contactly detect the location of the wind source and achieve object classification prediction when combined with the CNN model.

The Effect of Esophagogastroduodenoscopy on Intraocular Pressure.

Esophagogastroduodenoscopy (EGD) is an endoscopic examination of the upper gastrointestinal tract that requires insufflation with gas, leading to intra-abdominal hypertension (IAH). There is evidence suggesting that IAH positively correlates with intracranial pressure (ICP) and possibly with intraocular pressure (IOP). The aim of this study was to examine the effect of a routine screening EGD on the IOP. In this observational study, 25 patients were recruited; 15 males with a mean age of 50 ± 18 years and 10 females with a mean age of 45 ± 14 years. EGD was conducted under sedation in 21 subjects. Both eyes' IOP measurements were performed using Tonopen Avia in the sitting and left lateral decubitus positions before sedation and the start of EGD, and subsequently in the left lateral decubitus position when the endoscope reached the duodenum (D2) and at the end of the procedure. The final measurement was performed in the sitting position 10 min after the end of the procedure. The mean IOP in the sitting position was 15.16 ± 2.27 mmHg, and in the left lateral decubitus position, 15.68 ± 2.82 mmHg. When the gastroscope entered the D2, it was 21.84 ± 6.55 mmHg, at the end of the procedure, 15.80 ± 3.25 mmHg, and 10 min later, 13.12 ± 3.63 mmHg. There was a statistically significant IOP increase when the gastroscope entered the duodenum (p < 0.01). At the end of the gastroscopy, the IOP significantly decreased compared to the one registered when the gastroscope entered the D2 (p < 0.001) and it became similar to the values measured before the EGD, in the same left lateral decubitus position (p > 0.05). Significant changes in IOP were observed during the EGD. IOP fluctuations during EGD should be taken into account, especially in patients that need repeated EGDs during their life or in patients with glaucoma. Further studies are needed to better understand the short-effect and long-effect influence of an IOP increase in these patients.

Peningkatan Pengetahuan Ergonomi Tentang Prinsip Prinsip Dalam Gerakan Di Sekolah SMAN 2 Bireuen

The purpose of this socialization is to find out about increasing knowledge of ergonomics and the principles of movement at SMA N 2 Bireuen. The results of this activity with socialization and discussion can increase students' understanding of ergonomics and its principles. Increasing understanding of the ergonomics of ergonomic sitting positions among students at SMA N 2 Bireuen will help reduce the risk of physiological and ergonomic complaints, as well as improve academic performance at school. It is hoped that the school will carry out this movement regarding ergonomics.

Smart Chair Development using ESP32 Microcontroller – A Preliminary Study

In response to the coronavirus disease 2019 (COVID-19) pandemic, the shift to online delivery mode for most teaching faculties has increased the risk of chronic back and neck pain for students and teachers. While short-term adjustments like working from the couch or using an uncomfortable kitchen chair might seem tolerable for working adults or university students, these habits can have detrimental long-term impacts on body and health. Although the pandemic situation has improved, and people are gradually returning to physical workplaces and classrooms, many individuals still spend a significant amount of time sitting in front of screens for work and other activities. This explains why 70% of adults in Malaysia have experienced back and neck pain at least once in their lives. This pre-study proposes a smart chair equipped with sensors that alert users to correct their sitting posture and take screen breaks for stretching, potentially reducing the risk of future muscle aches and pain.

Cerebrovascular responses to a 90° tilt in healthy neonates

BackgroundTilts can induce alterations in cerebral hemodynamics in healthy neonates, but prior studies have only examined systemic parameters or used small tilt angles (<90°). The healthy neonatal population, however, are commonly subjected to large tilt angles (≥90°). We sought to characterize the cerebrovascular response to a 90° tilt in healthy term neonates.MethodsWe performed a secondary descriptive analysis on 44 healthy term neonates. We measured cerebral oxygen saturation (rcSO2), oxygen saturation (SpO2), heart rate (HR), breathing rate (BR), and cerebral fractional tissue oxygen extraction (cFTOE) over three consecutive 90° tilts. These parameters were measured for 2-min while neonates were in a supine (0°) position and 2-min while tilted to a sitting (90°) position. We measured oscillometric mean blood pressure (MBP) at the start of each tilt.ResultsrcSO2 and BR decreased significantly in the sitting position, whereas cFTOE, SpO2, and MBP increased significantly in the sitting position. We detected a significant position-by-time interaction for all physiological parameters.ConclusionA 90° tilt induces a decline in rcSO2 and an increase in cFTOE in healthy term neonates. Understanding the normal cerebrovascular response to a 90° tilt in healthy neonates will help clinicians to recognize abnormal responses in high-risk infant populations.ImpactHealthy term neonates (≤14 days old) had decreased cerebral oxygen saturation (~1.1%) and increased cerebral oxygen extraction (~0.01) following a 90° tilt.We detected a significant position-by-time interaction with all physiological parameters measured, suggesting the effect of position varied across consecutive tilts.No prior study has characterized the cerebral oxygen saturation response to a 90° tilt in healthy term neonates.

Surgeon fatigue in robot-assisted and laparoscopic gastrectomy for gastric cancer: Exploratory prospective observational study ancillary to JCOG1907 randomized controlled trial (JCOG1907A1).

TPS422 Background: Fatigue is being increasingly recognized as an important factor in surgical procedures, because it leads to errors in surgeons' decisions and reduced operating efficiency. In comparison to laparoscopic surgery, robot-assisted surgery is expected to reduce surgeon fatigue due to ergonomic adjustments, comfortable sitting positions, minimal restriction of instrument movement, and stable visualization. The aim of this study is to assess surgeon fatigue and explore the superiority of robot-assisted gastrectomy over laparoscopic gastrectomy in surgeon fatigue. Methods: This study is conducted as a prospective observational study ancillary to a randomized controlled phase III trial investigating the superiority in safety of robot-assisted gastrectomy over laparoscopic gastrectomy for clinical stage T1-4aN0-3 gastric cancer (JCOG1907: UMIN000039825). The lead surgeon and the first assistant performing surgeries as protocol treatment in JCOG1907 were included. Surgeon fatigue is quantitatively assessed using multiple assessment tools. The primary endpoint is the average NASA-Task Load Index (NASA-TLX) value for the lead surgeons. Secondary endpoints include six individual parameters of NASA-TLX, visual analog scale assessments for fatigue, advanced trail-making tests, and continuous heart rate variability measurements for lead surgeons and first assistants. The primary analysis compares surgeon fatigue between robot-assisted and laparoscopic surgery. Secondary analyses examine the association between surgeon fatigue and various factors, such as surgeon and patient background, and surgical findings, as well as cross-correlations among measures of surgical fatigue. In addition, the association between surgeon fatigue and postoperative complications and its impact on long-term survival outcomes is also evaluated. The sample size is 500 surgical cases, with a planned accrual period of 2 years. This study was initiated in April 2023 and registered at the University Hospital Medical Information Network as UMIN000052120. As of August 2023, 52 cases (10.4% of the planned accrual) have been enrolled in the study. Clinical trial information: UMIN000052120 .

The Comparison of the Effect of Prolonged Sitting on Lumbar Repositioning Error in Asymptomatic and Chronic Low Back Pain Participants with Seated Sedentary Behavior

Lumbar Repositioning Error (LRPE) refers to an individual’s capacity to perceive and control the precise position of their lumbar spine. An adequate lumbar repositioning is crucial for sustaining spinal stability and an optimal function during sitting activities. When lumbar repositioning is inaccurate, it can lead to ineffective movement patterns that might contribute to the development of low back pain (LBP). However, the impact of prolonged sitting on LRPE in asymptomatic individuals and those with chronic low back pain (CLBP) remains unexplored. To assess the effects of continuous 30 min sitting on LRPE and pain in asymptomatic and CLBP participants with sedentary behavior, 50 participants (25 asymptomatic and 25 CLBP) were recruited. Their LRPE and pain were measured before and after a 30 min sitting condition. Both groups experienced a significant increase in pain intensity after the 30 min sitting period (p = 0.001 for asymptomatic, p = 0.006 for CLBP). The LRPE remained unchanged in the asymptomatic group (p = 0.066), but it was significantly increased in the CLBP group (p = 0.001). Furthermore, the CLBP group exhibited significantly higher levels of LRPE and pain compared to the asymptomatic group after sitting (p = 0.041 and p = 0.001, respectively). Prolonged sitting posture is a risk of LBP, particularly in sedentary individuals. To prevent the exacerbation of LRPE and LBP, individuals with CLBP, especially those with sedentary lifestyles, should avoid sitting continuously for 30 min. These findings highlight the importance of physical therapists providing such guidance in practice. HIGHLIGHTS Prolonged sitting for 30 min appears to impact back pain CLBP participants experienced a significant increase in lumbar repositioning error (LRPE) after the 30 min sitting condition Physical therapists should advise people with sedentary lifestyles with low back pain to refrain from sitting for 30 min GRAPHICAL ABSTRACT

The Reverse Dual Plane: A Novel Technique for Endoscopic Transaxillary Breast Augmentation.

Quite a few Asian patients prefer axillary incision for breast augmentation. However, this surgery needs improvement. To introduce a reverse dual-plane technique through a transaxillary approach and compare it with a transaxillary dual-plane approach. Eighty-two patients were divided into Group A (n = 40) and Group B (n = 42). Axillary incision and endoscope were utilized in the 2 groups. Tebbetts' dual plane was performed in Group A patients. Patients in Group B underwent our reverse dual-plane technique, in which the upper 70% was subfascial and the lower 30% was subpectoral, with the fascia of the external oblique and anterior serratus being elevated together with the pectoral muscle. The Numeric Pain Rating Scale (NPRS) scores were recorded daily for 7 days. Breast shape and softness, in both sitting and supine positions, were assessed by the patients, and complications were compared. The NPRS scores of Group B patients were significantly lower than those of Group A patients (P < .01). The satisfaction rate of shape and softness in the seated position was not significantly different (P > .05). However, in the supine position, only 20 patients (50.0%) in Group A and 32 patients (76.2%) in Group B were satisfied with their breast softness (P < .01), and the breasts of the others became stiffer. Breast animation deformity (BAD) occurred in 2 patients in Group A and in no patient in Group B (P < .01). Other complications were not significantly different. Compared with Tebbetts' dual plane, this procedure significantly reduced pain, improved breast softness, and eliminated BAD, without increasing complications.

A Deep Learning-Based Chair System That Detects Sitting Posture.

Long-term poor sitting posture leads to physical injuries such as muscle soreness and waist and neck alignment problems. In this study, we proposed an intelligent sitting posture detection system that uses depth cameras fixed on a chair to capture depth images of the user's sitting posture, and then applies a trained artificial intelligence (AI) model on an embedded Raspberry Pi board to recognize the user's sitting posture from the image data. Finally, through Bluetooth on the Raspberry Pi, the results are sent to the user's smartphone application for display and recording to achieve rapid detection of sitting posture and warning of poor sitting posture. The contribution of this study is its use of two depth cameras mounted on a chair, thereby eliminating the problem of cumbersome sensors that compromise user comfort or are prone to damage. The detection of the user's entire sitting posture was completed on an edge computing platform, which leads to power savings and offers privacy protection. Furthermore, because of the low battery power usage, the system is portable. To perform quick AI calculations, we developed a lightweight EfficientNet model and programmed it for the Raspberry Pi. The system achieved an accuracy of 99.71% and an execution speed of almost one posture result per second.

Pushing forward: exploring the impact of the sitting position on muscle activation patterns and force generation during paralympic sit-cross-country skiing.

Paralympic cross-country sit-skiing is a discipline of the Paralympic Winter Games where athletes use a specialized sledge. Athletes are classified into different groups according to their functional abilities. The double poling technique is used to push the sledge forward and generate speed. Different sitting positions in the sledge are used based on the individual impairment. To date there is no data available on the effects of these different positions on muscle activation patterns. The aim of this study was to analyze the muscle activation patterns of the trunk and upper body muscles in relation to the poling force. Nine Able-bodied athletes were tested on a treadmill at submaximal speed in three sitting positions for 4 min in a flat and uphill condition. Sitting positions included a "knee-high" position, a "knee-low" position, and a "neutral" position with the sitting platform parallel to the ground. Unilateral pole forces and surface EMG from three trunk muscles, two upper limb muscles, and one lower limb muscle were recorded simultaneously on the dominate side. Data were segmented into individual cycles and mean values and standard deviations calculated for each subject and condition. Statistical analyses, including a Friedman test and Bonferroni correction, were applied to examine significant differences across different sitting positions. Our findings demonstrate that while certain muscle groups such as the erector spinae and triceps show consistent patterns of activation across different sitting positions, there is considerable variability among individual athletes, suggesting individualized strategies for task execution. Overall, force application was most efficient in the "knee low" position with 691.33 ± 148.83 N and least efficient in the "knee high" position with 582.81 ± 115.11 N. Testing impaired athletes will be the next step in understanding the neurophysiological aspects of the poling movement. This experimental protocol provides a basis for understanding the movement of paralympic cross-country sit-skiing in greater depth.

Potential differences in ephedrine requirements between left lateral and right lateral decubitus positions during neuraxial anesthesia for cesarean delivery.

The recent article by Wen et al., published in PLOS ONE, titled "Effects of neuraxial anesthesia in sitting and lateral positions on maternal hemodynamics in cesarean section: A systematic review and meta-analysis," caught my attention. In their study, the authors observed the effects of neuraxial anesthesia in sitting and lateral positions on maternal hemodynamics during cesarean section. Given the anatomical differences between the left and right sides of the body, which could result in differences in maternal hemodynamics and vasopressor requirements during neuraxial anesthesia for cesarean delivery, I was intrigued by the idea of further dividing the lateral position data from Wen et al.'s study into three subgroups: "left lateral position," "right lateral position," and "not mentioned" (where the included original study did not mention the lateral position) for a subgroup analysis. It seems to be more rigorous, the subgroup analysis revealed that the usage rate of ephedrine support was 1.42 times higher for parturients in the right lateral position compared to those in the sitting position. This finding supports our recommendation to distinguish between left and right lateral decubitus positioning in neuraxial anesthesia for cesarean delivery. But in contrast, no significant difference was observed between the sitting and lateral positions in terms of the number of parturients requiring ephedrine in Wen et al.'s. Given the limited research on the right-lateral position and its hemodynamic effects, further studies are needed to explore its clinical applications. Future research should also focus on conducting larger trials with greater sample sizes to evaluate the long-term neonatal outcomes associated with varying maternal positions. Additionally, researchers should conduct subgroup analyses that separate the left- and right-lateral positions to provide clearer guidance for anesthesiologists.

A modified supraorbital surgical approach for enucleation- exenteration in dromedary camels (camelus dromedarius): Clinical study.

Enucleation and exenteration are widely utilized ophthalmic procedures in veterinary field. Enucleation in camels is like other large animals, typically performed under the influence of heavy sedation and loco-regional analgesia. The aim of the current study was to introduce a new surgical approach to enucleate the eye of camels through supraorbital fossa approach. for that purpose, the technique was applied to seven camels referred to the King-fisal teaching veterinary hospital for unilateral enucleation. Assessment of applicability, safety and feasibility of this technique was done. All procedures were performed in the kush (sitting) position under the influence of heavy sedation with Xylazine HCl in combination with retrobulbar nerve block. A "C" shaped skin incision was made in the skin and fascia of the supraorbital fossa to enter the orbital cavity, after which the periorbital fat was gripped, dissected and removed. Bleeding controlled by electrocautery and visible large blood vessels were ligated. After ligation the optic nerve and ophthalmic blood vessels, the eyeball was dissected sharply and freed from the orbital bony attachment. Finally, the orbital fascia and skin were sutured with simple interrupted pattern separately. The approach proved successful in all camels, with the enucleation procedure being both feasible and easily performed. The mean surgical time was approximately 46.6±12.4 minutes. The minimal occurrence of short and long-term complications was encouraging, and the cosmetic outcomes were notably improved. The supraorbital approach is a safe and effective technique for camel ophthalmic surgery, showing advantages in exposure and minimal complications. Further research is needed for validation and broader clinical applications.

Self-Reported Work-Related Musculoskeletal Problems and Associated Risk Factors Among Three-Wheel Car Drivers in Ethiopia: A Cross-Sectional Community-Based Study.

Globally, the demand for mobility is increasing. Three-wheel cars are one of the best options for meeting this demand and creating new job opportunities in most developing countries, including Ethiopia. Drivers are highly susceptible to developing musculoskeletal disorders (MSDs). Even though several studies on other groups of drivers have been conducted, little is done in Ethiopia among three-wheel car drivers. This study investigated the prevalence of MSDs and identified their associated risk factors among three-wheel car drivers in Ethiopia. A community-based cross-sectional research was conducted among drivers of three-wheel cars from August 05 to October 07, 2022. A stratified sampling followed by a simple random sampling technique was used to select 422 respondents.Structured and pretested questionnaires adapted from the Nordic Musculoskeletal Questionnaire were used to collect the data. Epi-data version 4.2.0.0 and SPSS version 20 were used to enter and analyze the collected data, respectively. In the previous 12 months, 62.45% of three-wheel car drivers had musculoskeletal disorders in any body region (95% CI: 58.36, 66.14). The back pain was the most frequently reported site of pain in this study. This study showed that the habit of doing physical exercise, work experience, site of service, taking rest breaks while driving, and having comfortable sitting posture was risk factor for musculoskeletal pain. In this study, the overall 12-month prevalence of musculoskeletal problems among three-wheel car drivers was high. Periodic health checkups for drivers, lifestyle changes, delivering training, and creating awareness are important to address this high-burden occupation-related problem.

Conceptual Analysis of Lower Back Pain Resulting from Awkward Sitting Posture in Driver Vehicle Seat&amp;#8212;Systematic Review and Surveys

Conceptual Analysis of Lower Back Pain Resulting from Awkward Sitting Posture in Driver Vehicle Seat&amp;#8212;Systematic Review and Surveys

Overview of musculoskeletal pain complains in motorcycles and car drivers

Background: Motorcycle and car riders in Indonesia have a very high population. This results in the rider's body being in a prolonged static position every day while driving. Motorcycle and car riders are forced to drive a vehicle for at least 1 – 2 hours a day. Prolonged sitting positions can result in some musculoskeletal pain. This study aims to analyze the use of vehicles, both motorcycles and cars, in terms of driving duration and determine the incidence of musculoskeletal pain. Methods: This research uses a descriptive research design with a cross-sectional analysis. The data source for this research is primary data obtained by interviewing and using a questionnaire that refers to the Nordic Body Map to map musculoskeletal pain complaints felt by participants while driving. Results: The total population was 124 people, however, only 88 samples were willing to be research subjects in this study. The results shown that more than 60 percent of respondents felt musculoskeletal pain in their bodies because of driving. Driving for more than 3 hours a day is one of the factor causing the musculoskeletal pain. From the data that has been obtained, it can be seen that musculoskeletal pain is felt in almost all parts of the body. Furthermore, pain in the lower back and neck was the most painful area of the body that felt by the most respondents. The upper back/shoulder is also a part of the body that feels pain almost the same as the neck. Conclusion: Vehicle drivers, both motorcycles and cars, have quite a large percentage of experiencing musculoskeletal pain complaints. The parts of the body that experience the most of musculoskeletal pain complaints are the low back, neck and upper back or shoulders.

Experimental Ultrasound Approach for Studying Knee Intra-Articular Femur-Tibia Movements under Different Loads.

The purpose of the present study was to develop an experimental model for the study of intra-articular knee movements depending on the function of the knee joint and involved muscle groups under isometric stretching conditions with different loads. The experimental procedure included an ultrasound examination of a knee joint after isometric stretching in healthy men (n = 32). The changes (in millimeters) in the distances between the femur and tibia were measured using an ultrasound sonographer at three stages. The first stage was performed on ten (n = 10) healthy men in five different sitting and upright positions. In the second and third experimental model stages, lower limbs loading was applied to 22 participants. Our hypothesis, which was confirmed, was that as a result of increased loads on the participant's back, an intra-articular decrease in the femur-tibia cartilage surface distance would be observed. The accuracy of the created experimental model was improved over its three stages from 30% to 9%. Quantitative model data can help to create a mathematical model of the mechanical effects during the deformation of knee joint bone cartilage and it can also help outline some future tasks: increasing loading weights, enlarging participant groups, performing comparisons of men and women, and performing comparisons of healthy and pathological individuals.

Quantifying unsupported sitting posture impairments in humans with cervical spinal cord injury using a head-mounted IMU sensor.

Cross-sectional study. To evaluate unsupported sitting posture impairments and identify postural regulatory strategies in cervical spinal cord injury (cSCI) participants via a head-mounted IMU sensor. A research lab in the United States of America. cSCI participants and controls maintained postural stability during unsupported sitting with eyes either open or closed. The head-mounted IMU sensor recorded accelerometer data to calculate cumulative sway motion. The postural regulatory strategy was analyzed by assessing the normalized power spectral density (PSD) in four frequency bands: 0-0.1 Hz (visual regulation), 0.1-0.5 Hz (vestibular regulation), 0.5-1 Hz (cerebellar regulation), and >1 Hz (proprioception and muscle control). Significant increases in postural sway were observed in cSCI participants compared to controls during unsupported sitting. For cSCI participants, normalized PSD significantly increased in the low-frequency bands (0-0.1 Hz and 0.1-0.5 Hz) but decreased in the high-frequency band (>1 Hz) compared to controls. cSCI participants were more reliant on visual and vestibular systems for sitting balance, while depending less on proprioception and muscle control compared to controls. These findings suggest that the altered postural regulatory strategy is ineffective in maintaining postural stability during unsupported sitting, emphasizing the importance of proprioception and muscle control for seated postural stability in cSCI participants.