Joint Position Research Articles

Normative Scores and Test-Retest Reliability of Neck Strength, Endurance, and Proprioception Tests in Children and Adolescents

OBJECTIVE: To determine normative scores, test-retest reliability, and minimal detectable change for the neck flexor endurance test (NFET), craniocervical flexion test (CCFT), and joint position error test (JPET) in children. DESIGN: Cross-sectional. METHODS: Two hundred typically developing children (10-15 years) were recruited. Participants were screened for cervical spine instability using the alar and transverse ligament tests prior to administering the NFET, CCFT, and JPET. Testing was performed twice on the same day, 6 hours apart. RESULTS: For the younger age group, average NFET scores were as follows: females = 9.1 seconds, males = 10.1 seconds. Mean CCFT scores decreased with an increase in pressure (22 millimeters of mercury [mmHg]: females = 6.1 seconds [1], males = 6.8 seconds [1]; 30 mmHg: females = 4.07 seconds [1.1], males = 4.1 seconds [0.9]). For the CCFT, reliability reduced as pressure increased. The JPET had moderate reliability (ICC2, k = 0.4-0.63) with the highest error in right rotation (females = 14.1 cm [5], males = 13.4 cm [4.7]). The NFET had excellent reliability (ICC2, k = 0.96 [0.94-0.97], P<.001). CONCLUSION: The normative scores presented serve as a reference standard for future studies and for systematic screening and head and neck injury prevention. JOSPT Open 2024;2(4):348-353. Epub 20 May 2024. doi:10.2519/josptopen.2024.1135

Efficient fabrication of conductive sponges for wearable flexible sensors

In recent years, flexible and wearable sensors, particularly piezoresistive sensors, have been widely used in various fields such as human–computer interface, soft robotics, and artificial electronic skin. Three-dimensional (3D) conductive sponges have attracted widespread attention due to their excellent sensor performance, ease of manufacture, and seamless integration into circuits. Polydimethylsiloxane (PDMS) is widely used as an ideal substrate for these 3D conductive sponges due to its excellent chemical stability, good biocompatibility, and ideal mechanical properties. In this study, we synthesize a series of conductive silicone sponges (PCSs) by the one-pot thiol oxidative coupling reaction using commercially available multi-walled carbon nanotubes and poly((thiopropyl)methyl dimethylsiloxane). The PCSs possess controllable density and electrical conductivity. Moreover, the PCS-a sponge exhibits a wide pressure sensing range from 0.5 to 230 kPa with high-pressure sensitivity along with excellent mechanical and sensing stability. Pressure sensors fabricated using PCSs can be utilized in speech recognition systems and human activity monitoring such as arm/finger bending or walking while attached to joint positions. Additionally, they can also function as compressible switching devices for pressure alarms and LEDs.

Knee joint position sense and kinematic control in relation to motor competency in 13 to 14-year-old adolescents

BackgroundMotor competence (MC) is a key component reflecting one’s ability to execute motor tasks and is an important predictor of physical fitness. For adolescents, understanding the factors affecting MC is pertinent to their development of more sophisticated sporting skills. Previous studies considered the influence of poor proprioceptive ability on MC, however, the relationship between lower limb joint position sense, kinematic control, and MC is not well understood. Therefore, the aim of this study was to determine the relation between joint position sense and kinematic control with MC in adolescents during a lower limb movement reproduction task.MethodsThis study was a cross-sectional design. Young people (n = 427, 196 girls and 231 boys) aged 13 to 14 years were recruited. A movement reproduction task was used to assess joint position sense and kinematic control, while the Movement Assessment Battery for Children (mABC-2) was used to assess MC. In this study, participants were categorized into the Typically Developed (TD, n = 231) and Probable Developmental Coordination Disorder (DCD, n = 80) groups for further analysis of joint position sense, kinematic control, and MC between groups.ResultsKinematic data, specifically normalized jerk, showed a significant correlation with MC. There was no correlation between knee joint position sense and MC, and no group differences between DCD and TD were found.ConclusionsJoint position sense should not be used as a measure to distinguish TD and DCD. Rather than joint position sense, control of kinematic movement has a greater influence on the coordination of the lower limbs in adolescents. Movement control training should be implemented in the clinical setting to target kinematic control, rather than focus on joint position sense practice, to improve motor competency.Trial Registration IdentifierNCT03150784. Registered 12 May 2017, https://clinicaltrials.gov/study/NCT03150784.

RETRACTED ARTICLEResearch Progress on 2D Human Pose Estimation Based on Deep Learning

Human pose estimation (HPE) is a significant area of study within computer vision and artificial intelligence, which locates the position and pose of human joints through images or videos. HPE has advanced progress in computer vision and deep learning fields at the theoretical level, improved the efficiency and accuracy of neural networks, and supported the development of natural and efficient human-computer interaction systems. At the application level, HPE has extensive value in many fields, including security monitoring, motion analysis and health management, VR&AR, robotics technology, film and television production and animation, intelligent driving and assisted driving. This paper divides 2D HPE tasks into three categories: two-stage (top-down and bottom-up), single-stage, and other improvement strategies (Transformer-based methods and post-processing optimization methods). Although deep learning-based pose estimation algorithms have achieved remarkable results, they still face challenges, such as prediction in complex scenes, crowd and joint occlusion problems, and lightweight design of models. Future work should pay more attention to these challenges and extend pose estimation technology from 2D to 3D contexts.

Effects of Pilates Exercise Training on Static Balance and Lower Limbs Proprioception in Adult Females With and Without Flexible Flatfeet.

It is well known that flatfeet are associated with a higher incidence of lower limb injuries in different populations. Thus, we examine how Pilates exercise training affects static balance and ankle and knee proprioception in females with and without flexible flatfeet. Study Design. Case series; Level of evidence. This quasi-experimental study involves 91 healthy 18- to 25-year-old female university students. The Navicular Drop Test was used to diagnose flatfeet. Pilates included core strength, balance, and flexibility exercises for 16 weeks. Static balance was assessed using the sharpened Romberg test and ankle and knee joint proprioception were measured using joint position reproduction tests. The Wilcoxon test indicated within-group pre-post improvements in static balance, and ankle and knee joint proprioception in the Pilates and the healthy control group (P < .05). The between-group comparisons at post-test showed significant differences for joint position reproduction test of the dorsiflexion (P < .05, η2 = 0.10) and the plantarflexion (P < 0.05, η2 = 0.08) in favor of the healthy controls group. Joint proprioception of ankle and knee was positively correlated with increasing static balance in the healthy control group. The results showed that Pilates has the potential to improve static balance, and ankle and knee proprioception. However, it did not improve postural control and proprioception in individuals with flatfeet. Our findings advise combining Pilates with other interventions to develop flexible flatfeet in females. Level I.

Assessing the reliability of a digital inclinometer app for measuring hip, knee, and ankle proprioception.

Proprioception can be defined as the ability of an individual to detect motion and position of the various joints in their bodies. Current tools for measuring proprioception lack consensus on their accuracy and validity; they also each have their own limitations, and, furthermore, present barriers to use for clinicians. We propose a new and reliable method for evaluating hip, knee, and ankle proprioception by utilizing a digital inclinometer app to measure joint position sense. The digital inclinometer app recorded the active joint position sense error after each of five trials for the hip and knee joint and ten trials for the ankle joint. To quantify the reliability of the digital inclinometer app, single-measurement and average-measurement intra-class correlation coefficients (ICC) along with the associated 95% confidence intervals (95% CI) were calculated for each joint's position sense error across trials. Both the hip (ICC (2,k) = 0.849 (95% CI = [0.783-0.897])) and knee joint (ICC (2,k) = 0.837 (95% CI = [0.750-0.897])) were found to have moderate to good reliability when the middle three of five trials were analyzed. Unlike the hip and knee, moderate to good reliability for ankle proprioception (ICC (2,k) = 0.785 (95% CI = [0.539-0.893])) was only achieved with the middle eight of ten trials. The results of this study indicate that this digital inclinometer app is able to accurately record joint position sense at the hip, knee, and ankle when the appropriate number of trials are collected; thus, allowing this tool and methodology to be considered for use in both clinical and research environments to measure proprioception, and furthermore, quantify proprioceptive deficits.

Pressure distribution based 2D in-bed keypoint prediction under interfered scenes

In-bed pose estimation holds significant potential in various domains, including healthcare, sleep studies, and smart homes. Pressure-sensitive bed sheets have emerged as a promising solution for addressing this task considering the advantages of convenience, comfort, and privacy protection. However, existing studies primarily rely on ideal datasets that do not consider the presence of common daily objects such as pillows and quilts referred to as interference, which can significantly impact the pressure distribution. As a result, there is still a gap between the models trained with ideal data and the real-life application. Besides the end-to-end training approach, one potential solution is to recognize the interference and fuse the interference information to the model during training. In this study, we created a well-annotated dataset, consisting of eight in-bed scenes and four common types of interference: pillows, quilts, a laptop, and a package. To facilitate the analysis, the pixels in the pressure image were categorized into five classes based on the relative position between the interference and the human. We then evaluated the performance of five neural network models for pixel-level interference recognition. The best-performing model achieved an accuracy of 80.0% in recognizing the five categories. Subsequently, we validated the utility of interference recognition in improving pose estimation accuracy. The ideal model initially shows an average joint position error of up to 30.59 cm and a Percentage of Correct Keypoints (PCK) of 0.332 on data from scenes with interferences. After retraining on data including interference, the error is reduced to 13.54 cm and the PCK increases to 0.747. By integrating interference recognition information, either by excluding the parts of the interference or using the recognition results as input, the error can be further minimized to 12.44 cm and the PCK can be maximized up to 0.777. Our findings represent an initial step towards the practical deployment of pressure-sensitive bed sheets in everyday life.

The Relationships Between Wrist Joint Position Sense, Anthropometric Characteristics and Grip Strength of the Hand in Healthy Individuals

The Relationships Between Wrist Joint Position Sense, Anthropometric Characteristics and Grip Strength of the Hand in Healthy Individuals

Effects of gait retraining in knee joint position sense

BackgroundJoint position sense (JPS) is crucial for maintaining posture, protecting joints, and carrying out daily activities such as walking. Studies show that exercises to strengthen muscles and improve proprioception can positively impact JPS during passive and less complex activities. Evidence suggests that motor training can effectively enhance sensory function, including JPS, due to the extensive connections between the motor cortex and somatosensory areas. Gait retraining using real-time feedback has improved outcomes among patients with musculoskeletal disorders. The effect of gait retraining on JPS has not been investigated. This study assessed the effects of gait retraining to reduce knee extension in joint position sense in individuals with knee hyperextension walking patterns. MethodsTen women with asymptomatic knee hyperextension (KH) >5° during overground walking participated in this study. Sagittal-plane kinematics were assessed using a three-dimensional (3D) motion analysis system. The JPS was assessed using the Knee Position Active Reproduction Test. The knee with the highest hyperextension was the focus of the gait retraining intervention, which consisted of six 1-h sessions using verbal instructions and visual kinematic feedback. Comparisons of peak knee extension during walking and knee JPS overall error (RMSE) were made using a paired t-test. ResultsGait retraining intervention significantly reduced knee extension angle during walking (83.8 % change; p < 0.001; Cohen's d = −1.6) and improved knee JPS (62 % change; p = 0.023; Cohen's d = 0.8) post-training. In addition, the improvements in joint kinematics (36.7 % change; p = 0.005; Cohen's d = −1.2) and JPS (52.6 % change; p = 0.015; Cohen's d = 0.9) were observed in the untrained knee. SignificanceGait retraining can improve joint position sense. This study addresses a gap in our understanding of how gait retraining can influence JPS. Our results corroborate that gait retraining is an evolving and promising strategy for improving gait outcomes, particularly in individuals with KH walking patterns.

The influence of different intensity of Tan Tui exercises on the posture control of students in the Tai Chi Elective Course: protocol for a randomized controlled trial

BackgroundTai Chi (TC) holds a unique and valued place in promoting the physical and mental health of college students. Its significance is underscored by its incorporation as a compulsory physical education course in every university in China. TC, with its rich tradition, places a strong emphasis on posture control as a core sports ability. However, the students in Tai Chi Elective Course (TCEC) have very poor posture control ability. This study protocol investigates the potential of Tan Tui (TT) to address these issues, as TT is a fundamental skill for beginners of traditional Chinese martial arts and has a track record of enhancing lower limb strength and balance, making it a promising choice for improving posture control in TCEC.Methods/designTo investigate the impact of different intensities of TT exercises on posture control in TCEC students, we have designed a randomized, double-blind, parallel-controlled trial. Seventy-six students in the TCEC will be randomly divided into low-intensity Tan Tui (LTT), medium-intensity Tan Tui (MTT), and high-intensity Tan Tui exercises group (HTT) and control group (CON), each with 19 people. The LTT group, MTT group, and HTT group will be given different intensity of TT exercises, and the CON group will be given regular TCEC. The intervention period will be 6 weeks (2 times a week, 20 min each time). At baseline (before), 4 weeks of intervention (middle), and 6 weeks of intervention (after), the Unipedal Stance Test (UST), the Star Excursion Balance Test (SEBT), 60°/s angular velocity knee joint flexion and extension relative peak torque (RPT), and knee joint position perception (KJPP) will be evaluated.DiscussionThis is the first randomized controlled trial protocol from the perspective of training intensity to evaluate the effect of different intensity of TT exercises on posture control of students in TCEC. Should our research reveal a significant intervention effect, the results will offer preliminary, higher-quality evidence supporting the positive impact of varying intensities of Tan Tui exercises on posture control in TCEC students.Trial registrationChinese Clinical Trial Registry ChiCTR2000039109. Registered on October 17, 2020.

Cervical Sensorimotor Function Tests Using a VR Headset-An Evaluation of Concurrent Validity.

Sensorimotor disturbances such as disturbed cervical joint position sense (JPS) and reduced reaction time and velocity in fast cervical movements have been demonstrated in people with neck pain. While these sensorimotor functions have been assessed mainly in movement science laboratories, new sensor technology enables objective assessments in the clinic. The aim was to investigate concurrent validity of a VR-based JPS test and a new cervical reaction acuity (CRA) test. Twenty participants, thirteen asymptomatic and seven with neck pain, participated in this cross-sectional study. The JPS test, including outcome measures of absolute error (AE), constant error (CE), and variable error (VE), and the CRA test, including outcome measures of reaction time and maximum velocity, were performed using a VR headset and compared to a gold standard optical motion capture system. The mean bias (assessed with the Bland-Altman method) between VR and the gold standard system ranged from 0.0° to 2.4° for the JPS test variables. For the CRA test, reaction times demonstrated a mean bias of -19.9 milliseconds (ms), and maximum velocity a mean bias of -6.5 degrees per seconds (°/s). The intraclass correlation coefficients (ICCs) between VR and gold standard were good to excellent (ICC 0.835-0.998) for the JPS test, and excellent (ICC 0.931-0.954) for reaction time and maximum velocity for the CRA test. The results show acceptable concurrent validity for the VR technology for assessment of JPS and CRA. A slightly larger bias was observed in JPS left rotation which should be considered in future research.

Correlations of temporomandibular joint morphology and position using cone-beam computed tomography and dynamic functional analysis in orthodontic patients: A cross-sectional study.

To correlate temporomandibular joint (TMJ) morphology and position with cone-beam computed tomography (CBCT) images, Joint Vibration Analysis (JVA), and Jaw Tracker (JT) to develop a radiation-free, dynamic method for screening and monitoring the TMJ in orthodontic patients. A total of 236 orthodontic patients without symptoms of TMJ disorders who had undergone CBCT were selected for the JVA and JT tests in this cross-sectional study. TMJ position and morphology were measured using a three-dimensional analysis software. JT measurements involved six opening-closing cycles, and JVA measurements were performed using a metronome to guide the mouth opening-closing movements of the patients. The correlations among the three measuring devices were evaluated. Abnormalities in condylar surface morphology affected the mandibular range of motion. The cut-off value results show that when various measurement groups are within a certain range, abnormalities may be observed in morphology (area under the curve, 0.81; P < 0.001). A 300/< 300 Hz ratio ≥ 0.09 suggested abnormal morphology (P < 0.05). Correlations were observed among the maximum opening velocity, maximum vertical opening position, and joint spaces in the JT measurements. Correlations were also observed between the > 300/< 300 Hz ratio, median frequency, total integral, integral < 300 Hz, and peak frequency with joint spaces in the JVA measurements. JT and JVA may serve as rapid, non-invasive, and radiation-free dynamic diagnostic tools for monitoring and screening TMJ abnormalities before and during orthodontic treatment.

Longitudinal assessment of knee joint proprioception using weight-bearing and non-weight-bearing tests throughout rehabilitation after anterior cruciate ligament reconstruction

ObjectiveEvaluate active knee joint position sense (JPS) throughout rehabilitation after anterior cruciate ligament reconstruction (ACLR). DesignLongitudinal. SettingMotion laboratory. ParticipantsTwenty-two individuals post-ACLR and 22 activity-matched non-injured controls performed weight-bearing and non-weight-bearing knee JPS tests. The ACLR participants performed at three functional timepoints: T1, able to perform single-leg sit-to-stand; T2, able to hop maximally; T3, cleared for return to sports. Controls performed on one occasion. Main outcome measuresConstant, absolute, variable errors (CE, AE, VE) and interlimb symmetry estimates (100% signifying perfect symmetry), for 40° and 65° knee flexion target angles. ResultsFor the weight-bearing 40° condition, CE and AE of the ACLR knee significantly increased from T1 to T2 (P = 0.010) and T1 to T3 (P = 0.002). Consequently, interlimb asymmetry for AE significantly increased from T1 (AEsym% = 101.2% ± 55.4%) to T3 (AEsym% = 139.7% ± 54.8%). Compared to controls, AE for the ACLR knee was significantly smaller at T1 (P = 0.016). No other significant differences were observed. ConclusionsSmaller JPS errors at early rehabilitation while weight-bearing may have been due to heightened quadriceps activation and increased γ motor neuron sensitivity, compensating for deficient ACL mechanoreceptors. In contrast, non-weight-bearing testing did not reveal changes over time. Clinicians are advised to consider these distinctions when assessing proprioception at different rehabilitation stages.

Comparative Impact of Core Stabilization vs Proprioceptive Neuromuscular Facilitation Exercises on Muscle Activation, Endurance, and Balance in Obese Children: A Randomized Controlled Trial.

BACKGROUND The purpose of the study was to compare the effects of core stabilization exercise (CSE) and proprioceptive neuromuscular facilitation (PNF) exercise on core muscle activation, core muscle endurance, proprioception, and balance in 80 obese children. MATERIAL AND METHODS In this single-blind, randomized controlled study, 80 obese children aged 10-13 years were randomly divided into 3 groups. The first group received CSE (n=27) and the second group received PNF exercises (n=27) 3 days a week for 8 weeks. The third group, which was the control group (n=26), received no treatment. Participants were evaluated before treatment (BT) and after treatment (AT) and at follow-up (3 months after treatment). Core muscle activation level was evaluated by Sahrmann Core Stability test (SCST), lumbar core muscle endurance was evaluated by McGill core endurance tests, and lumbar joint position sense (JPS) was evaluated by laser cursor. The single-leg standing balance test (SLSBT) and Y balance test (YBT) were used for static and dynamic balance, respectively. RESULTS AT and at follow-up, core activation, core endurance, JPS, and static balance were significantly different between the groups (P<0.05). There was no significant difference between the groups in YBT dominant and non-dominant side mixed reach distances (P>0.05). Clinical effect sizes were higher in the CSE group for all outcome measures. CONCLUSIONS CSE and PNF exercises improve the level of core muscle activation, lumbar core muscle endurance, lumbar JPS, and balance in obese children. However, the results of this study show that CSE are more clinically effective in obese children. The effects decline in the medium term.

Unity and ROS as a Digital and Communication Layer for Digital Twin Application: Case Study of Robotic Arm in a Smart Manufacturing Cell.

A digital twin (DT) is a virtual/digital model of any physical object (physical twin), interconnected through data exchange. In the context of Industry 4.0, DTs are integral to intelligent automation driving innovation at scale by providing significant improvements in precision, flexibility, and real-time responsiveness. A critical challenge in developing DTs is achieving a model that reflects real-time conditions with precision and flexibility. This paper focuses on evaluating latency and accuracy, key metrics for assessing the efficacy of a DT, which often hinder scalability and adaptability in robotic applications. This article presents a comprehensive framework for developing DTs using Unity and Robot Operating System (ROS) as the main layers of digitalization and communication. The MoveIt package was used for motion planning and execution for the robotic arm, showcasing the framework's versatility independent of proprietary constraints. Leveraging the versatility and open-source nature of these tools, the framework ensures interoperability, adaptability, and scalability, crucial for modern smart manufacturing applications. Our approach was validated by conducting extensive accuracy and latency tests. We measured latency by timestamping messages exchanged between the physical and digital twin, achieving a latency of 77.67 ms. Accuracy was assessed by comparing the joint positions of the DT and the physical robotic arm over multiple cycles, resulting in an accuracy rate of 99.99%. The results highlight the potential of DTs in enhancing operational efficiency and decision-making in manufacturing environments.

Analysis of Polynomial Interpolation Characteristics Based on 6DOF Manipulator Trajectory Planning

Aiming at the problems of choosing and using polynomials of different times and mixed polynomials in the process of manipulator trajectory planning, such as difficulty, wide range of light and low accuracy, in this paper, the application of different polynomials in manipulator trajectory planning is systematically analyzed by using MATLAB Robot Toolbox simulation platform and Polynomial interpolation algorithm. Using a 6-dof robotic arm Puma560 as a simulation object, the effects of three-, five-, and seven-Polynomial interpolation on joint position and pose in joint space trajectory planning were analyzed, a preliminary understanding of the application of different polynomials, and secondly, the more complex application of the fifth and seventh degree polynomials in Descartes space for the trajectory planning of the manipulator, the influence of trajectory planning with different degree polynomials on the position and pose of manipulator joint is clarified. The results show that the higher the number of polynomials, the smoother the transition of the joint at the critical path points, but the greater the maximum angular velocity and angular acceleration of the joint, the Polynomial interpolation of joint space and Descartes space trajectory planning are 14% and 23% lower than the average of absolute maximum angular velocity and absolute maximum angular acceleration of the Polynomial interpolation, respectively. Based on the analysis of the research results, this paper presents the applicable conditions and applications of Polynomial interpolation method in trajectory planning, and further summarizes the application conditions and methods of mixed polynomials.

Influence of texting while walking on lower extremity gait function in young adults

Texting while walking (TWW) is a dual-task activity that young adults perform in their everyday lives. TWW has been reported to affect gait characteristics such as gait speed, stride length, and cadence. However, the influence of TWW on lower extremity gait function has not been investigated. Therefore, the purpose of this study was to quantify gait function by examining gait symmetry and using a time series analysis. Twenty-eight young adults (14 males, 14 females) walked at their preferred speed for 10 m as a baseline condition and a 10 m TWW task. Three-dimensional segment tracking was achieved utilizing a lower extremity and trunk marker set and the Model Statistic was used to test for statistical differences between the hip, knee, and ankle angular joint positions. The hip yielded the most asymmetries (25 out of 101 points) throughout the gait cycle, while asymmetries for the knee and ankle joints yielded 16 out of 101 points and 11 out of 101 points, respectively. The outcomes of this study suggest there are differences between baseline and TWW gait symmetry, however, the percentage of the gait cycle affected was less than 25 % - indicating gait function is not strongly influenced by texting while walking in young adults.

THE EFFECT OF TRUNK STABILITY TRAINING ON UPPER EXTREMITY ENDURANCE, STABILITY AND SHOULDER JOINT PROPRIOCEPTION IN POSTMENOPAUSAL WOMEN

Purpose: The incidence of shoulder pathologies is increasing in postmenopausal women. In this period, there is a need for protective approaches to be applied to prevent shoulder injuries. The aim of this study is to investigate the effects of clinical pilates exercises on upper extremity stability, endurance, function and shoulder joint proprioception in postmenopausal women. Methods: 30 postmenopausal women between the ages of 40-60 were included in our study. Participants were given clinical pilates training for 6 weeks, 3 days a week, 60 minutes by a physiotherapist. Before and after pilates training, dynamic stability of the shoulder was evaluated with Closed Kinetic Chain Upper Extremity Stability Test (CKCUES Test) and Upper Quarter Y Balance Test (UQYBT). Upper extremity muscle endurance was evaluated with the modified push up test. Laser Pointer-Assisted Angle Reproduction Test (LP-ART) was used to evaluate shoulder joint position sense. Results: A statistically significant difference was found in CKCUES Test (p=0.000, r=0.594), UQYBT (p=0.000, r=0.537), modified push up (p=0.000, r=0.594), LP-ART abduction (p=0.000, r= 0.491) and LP-ART flexion (p=0.000, r=0.484) at end of the training compared to the pre-training. The exercise program was found to be highly effective on all parameters. Conclusion: It was concluded that clinical pilates training applied in postmenopausal women increased the dynamic stability of the shoulder, endurance and position sense. Trunk stabilization exercises may be beneficial as a preventive approach in the prevention of shoulder pathologies in postmenopausal women.

Study on Stress Characteristics Response of Submarine Shield Segment Under Ultra-high Water Pressure

In the construction and operation stage of shield tunnel, mastering and clarifying the mechanical characteristics of the overall structure is essential for ensuring shield tunnel safety. In this paper, the shell-spring model is established by ABAQUS finite element software for the ultra-high water pressure submarine shield tunnel. The mechanical behavior of shield segment structure under varying water pressure, different key block position and different strata is studied and analyzed. The results show that at the same segment assembly position, the axial force of the segment increases greatly with the increase of water pressure, and the growth rate is as high as 150 %. The internal force of the segment is mainly axial force. Under the ultra-high water pressure, the corresponding position of the maximum deformation of the segment is related to the position of the segment joint at the arch bottom. In the staggered assembly, the axial force fluctuation near the arch bottom is larger than that of the straight assembly, and the peak bending moment and the maximum axial force are near the invert. In addition, near the 120 degree of the vault, the bending moment oscillates obviously near the joint in the stratum with small coefficient of soil reaction. The larger the coefficient of soil reaction is, the more uniform the axial force of the whole segment is. The research results provide a theoretical insights for the optimization design of shield tunnel segments.

Effect of the Material Properties and Knee Position to the Bone Bruise Pattern in Skeletally Mature and Immature Subjects.

A bone bruise is generated by a bony collision that could occur when the ACL is injured, and its pattern supposedly depends on the injury mechanism and level of skeletal maturity. The objective of this study was to determine the effect of material properties and knee position on the bone bruise pattern in skeletally mature and immature subjects using finite element analysis. Finite element models were created from an MR image in the sagittal plane of a skeletally mature and immature male subject. The femur and tibia were collided at 2 m/s to simulate the impact and determine the maximum principal stress. The analysis was performed at 15, 30 and 45 degrees of knee flexion, and neutral, 10 mm anterior and posterior translated position at each flexion angle. Although high stress was distributed toward the metaphysis area in the mature model, the stress did not cross the growth plate in the immature model. The size of the stress area was larger in the mature model than those in the immature model. The location of the stress area was dependent on the joint position as well as Young's modulus of cartilage and trabecular bone. Thus, the bone bruise pattern was affected by the knee position and tissue quality. In conclusion, although the bone bruise distribution was generally called footprint of the injury, the combined evaluation of the quality of the structure and the bone bruise distribution is necessary for properly diagnosing tissue injury based on the MR imaging.