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The Rearfoot Angle (RFA) is the most commonly method used for foot posture assessment, and it is also a method for evaluating the subtalar joint neutral foot posture. However, orthopedists and researchers often meet trouble for the measurements of the RFA and neutral foot posture due to lacking measurement with automation and objectivity. In general, the RFA was measured using a goniometer to align with manual markers on the foot. The purpose of this study implements the automatic computing of leg angle, foot angle, and RFA by the foot model using Three-Dimensional (3D) scanning. This study contributes to the algorithms to The purpose of this study implement the automatic and objective computing of leg angle, foot angle, and RFA by the foot model using 3D scanning. The automatic calculation on leg angle, foot angle, and neutral foot posture has been created, test, and validated completely in this study. There are two algorithm methods proposed to determine the midpoint on the leg or foot outline. The midline has been computed by linear regression through five midpoints. The leg and foot angles are calculated by the tibial and calcaneal midlines, respectively. Through the subject standing on eversion foot platforms, the neutral posture of the foot can be computed by the leg and foot angles determined by the 3D model scanned of the foot with various tilt angles. The determinations of the midpoint and midline have been demonstrated algorithm by MATLAB. Based on comparing with the goniometer measured, selecting the midpoint algorithm of the limit points and the lowest point methods to determine the tibial and calcaneal midlines respectively would carry out better results. The foot 3D scanning measurement proposed in this study has been tested and validated from the goniometer. This study can determine the leg angle, foot angle, and neutral foot postures for a subject with normal weight status, but be not suitable for that with obese weight status. In the future, this study can provide guidance for foot posture assessment and personal insoles design.

Summary Objectives In rugby union scrummaging, front-row players often sustain lumbar spine injuries, which can lead to physical impairments and absence from play. Poor lumbar spine posture adopted by front-row players during scrummaging may contribute to these lumbar spine injuries. However, few studies have investigated lumbar spine kinematics in front-row players during scrummaging and therefore little is known about what factors influence lumbar spine posture. The focus of this study was to determine whether interactions with other players affect front-row players’ ability to adopt and/or maintain a neutral lumbar spine posture. Equipment and methods Lumbar spine kinematics were investigated in 15 front-row players during scrums under two conditions: (i) one-man scrums, and (ii) scrums with the support of two second-row players. Lumbar spine three-dimensional kinematics were obtained using a system of five digital single-lens reflex cameras and photogrammetric software package. A Bayesian approach was used to determine the effect of scrummaging conditions. Results The results showed that players adopt neutral posture when scrummaging alone. In contrast, when supported by second-row players, participants adopted a flexed posture (kyphosis), which may contribute to lumbar spine injuries. However, the supported scrum condition did not change lateral-flexion (0° to 2°) and axial rotation (0° to 2°) of the spine substantially. These results suggest that training and rehabilitation programs should focus on practicing a neutral posture during scrums involving second-row players to minimise spinal stress.

Purpose: This purpose of the study was to identify the effects of computer worktable heights on musculoskeletal changes in the neck and upper extremities and postural alignment in patients with C6 and T6 level spinal cord injuries. Materials and Methods: The participants in the present study were patients diagnosed with AIS A. The level of the worktable was set 5 cm below the elbow, at elbow level, and 5 cm above elbow level. Subjective musculoskeletal discomfort (Borg-RPE) was measured at the end of the experiment. To compare the side posture for the wheelchair axle, patients with C6 and the T6 injuries were selected to measure the angle of the centerline for the axle, the tip of the chin, and the postural change for the tragus of the ear. Results: First, in the patient with C6 injuries, the Borg-RPE scores decreased when the worktable height was 5 cm above the elbow, whereas, in the patient with T6 injuries, the Borg-RPE scores decreased when the worktable height was decreased. Second, in the patient with C6 injuries, the chin tip and tragus of the ear were close to the center of the wheelchair when the height of the worktable was 5 cm above the elbow in the lateral position. In the patient with T6 injuries, there was no difference in lateral posture according to the height of the worktable. Conclusion: To reduce musculoskeletal system discomfort in patients during video display terminal (VDT) work, it is necessary to set the worktable height higher than the elbow standard for patients with C6 injuries and lower than elbow height for patients with T6 injuries. In the case of posture change, in the patient with C6 injuries, the higher the worktable height, the more the neck and head changed from forward flexion to a neutral posture.

Study design Observational Study. Objective The primary objective was to determine if there were differences in spine structure measures between experimental postures and standard supine posture MRIs. Methods Thirty-four low back pain patients were included. MRI was taken in 6 experimental postures. The dependent measures includes sagittal view anterior (ADH), middle and posterior disc heights, thecal sac width, left/right foraminal height (FH). In the axial view: disc width, left and right foraminal height. Measures were done L3/L4, L4/L5 and L5/S1. Each subject served as their own control. Spine measurements in the experimental posture were compared to the same measures in the standard supine posture. Results 94% inter-observer reliability was seen. In the sagittal and axial view, 55 of the 108 and 11 of the 18 measures were significantly different. In sagittal view: a) ADH was significantly smaller in the sitting flexed posture by 2.50 mm ± 0.63 compared to the supine posture; b) ADH in sitting neutral posture was significantly smaller than the standard posture by 1.97 mm ± 0.86; c) sitting flexed posture showed that bilateral FH measures were significantly different; d) Bilateral FH was larger in the sitting neutral posture compared to the standard supine posture by 0.87 mm ± 0.17. Conclusions This research quantifies the differences in spine structure measures that occur in various experimental postures. The additional information gathered from an upright MRI may correlate with symptoms leading to an accurate diagnosis and assist in future spine research.

To evaluate the biomechanical properties of the upper thoracic spine in anterior-posterior shear loading at various displacement rates. These data broaden our understanding of thoracic spine biomechanics and inform efforts to model the spine and spinal cord injuries. Seven T1-T2 thoracic functional spinal units were loaded non-destructively by a pure shear force up to 200 N, starting from a neutral posture. Tests were run in both posterior and anterior directions, at displacement rates of 1, 10, and 100 mm/s. The three-dimensional motion of the specimen was recorded at 1000 Hz. Individual and averaged load-displacement curves were generated and specimen stiffnesses were calculated. Due to a nonlinear response of the specimens, stiffness was defined separately for both the lower half and the upper half of the specimen range of motion. Specimens were significantly stiffer in the anterior direction than in the posterior direction, across all rates. At low displacements, the anterior stiffness averaged 230 N/mm, 76% higher than the low displacement posterior stiffness of 131 N/mm. At high displacements, anterior stiffness averaged 258 N/mm, 51% stiffer than the high displacement posterior stiffness of 171 N/mm. Shear displacement rate had a small effect on the load response, with the 100 mm/s rate causing a mildly stiffer response at low displacements in the anterior direction. Overall, the load-displacement response exhibited pseudo-quadratic behavior at 1 and 10 mm/s but became more linear at 100 mm/s. The shear stiffness in the upper thoracic spine is greatest in the anterior loading direction, being 51%-76% greater than posterior, most likely due to facet interactions. The effect of the shear displacement rate is low.

BACKGROUND: The aim of the study was to determine the characteristics of cervical muscle activity in different head movements when using helmet mounted display in air combat maneuvering.METHODS: Cervical EMG was measured with eight F/A-18 pilots using the Joint Helmet Mounted Cueing System (JHMCS) during air combat maneuvering. In-flight Gz acceleration and continuous head position were recorded. Muscular activity was compared between head movements in isolation and combined with torso movement. In addition, the effect of the direction of head movements and the use of head support of the ejection seat on muscle activity was determined.RESULTS: Muscular loading increased in the cervical flexors and extensors when using the torso during targeting beyond the field of vision in the neutral sitting posture; the difference was significant in the flexors, but activity levels were higher in the extensors. Cervical muscles are loaded to a lesser extent if the head is kept in a stable position during Gz loading. Muscular activity in the neck muscles was higher when the pilot was moving the head out of neutral posture rather than toward neutral posture. The use of the headrest as a support decreased muscle activity in the extensors, but resulted in higher activity in the flexor muscles.DISCUSSION: All analyzed conditions were significantly affected by an increase in Gz. An increase of muscle activity with torso movements is considered as a positive factor as it reflects maintained muscular support for the cervical spine. Presented results may be helpful when specific conditioning programs and cockpit ergonomics are developed for fighter pilots.Sovelius R, Mäntylä M, Huhtala H, Oksa J, Valtonen R, Tiitola L, Leino T. Head movements and neck muscle activity during air combat maneuvering. Aerosp Med Hum Perform. 2020; 91(1):26–31.

To date, no in vivo study is available regarding the measurement of the contact area of the metacarpophalangeal joints (MP joints) and carpometacarpal joints (CM joints) when the subject grasps specific objects; therefore, this study conducted magnetic resonance imaging of fingers in the neutral posture and while grasping three spheres with different diameters and measured the contact areas of the second to fifth MP and CM joints. The study included six Japanese male subjects with no hand injuries or disorders. The following four postures were used: neutral posture, in which all fingers were extended without holding a sphere, and postures while grasping three different spheres with varying diameters (40, 67, and 97 mm). In the second MP joint, the contact area while grasping a ping-pong ball (diameter, 40 mm) was significantly larger than that while grasping a tennis ball (diameter, 67 mm). Although the grasped spheres were changed, no significant changes were observed in the contact areas of joints other than the second MP joint. The contact areas of the second and third CM joints were significantly larger than those of the fourth and fifth CM joints. In the fourth CM joint, the contact area in the neutral posture was significantly larger than that while grasping a tennis and ping-pong ball. In the second and third CM joints, no significant changes were observed in the contact area of each bone, although the posture was changed.

Objective The purpose of this study was to investigate the interaction between thoracic movement and lumbar muscle co-contraction when the lumbar spine was held in a relatively neutral posture. Methods Thirty young adults, asymptomatic for back pain, performed 10 trials of upright standing, maximum trunk range of motion, and thoracic movement tasks while lumbar muscle activation was measured. Lumbar co-contraction was calculated, compared between tasks, and correlated to thoracic angles. Results Movement tasks typically exhibited greater co-contraction than upright standing. Co-contraction in the lumbar musculature was 67%, 45%, and 55% greater than upright standing for thoracic flex, thoracic bend, and thoracic twist, respectively. Generally, the thoracic movement task demonstrated greater co-contraction than the maximum task in the same direction. Co-contraction was also correlated to thoracic angles in each movement direction. Conclusion Tasks with thoracic movement and a neutral lumbar spine posture resulted in increases in co-contraction within the lumbar musculature compared with quiet standing and maximum trunk range-of-motion tasks. Findings indicated an interaction between the 2 spine regions, suggesting that thoracic posture should be accounted for during the investigation of lumbar spine mechanics.

Persons with low back pain (LBP) have demonstrated altered morphology and function of the deep multifidus (DM). This study examined the effects of postural cueing for increased lumbar lordosis on DM and longissimus thoracis (LT) activation during lumbar stabilization exercises (LSE) performed by persons with LBP. Nine adults with a history of chronic or recurrent LBP were recruited. Fine-wire EMG data was collected while participants performed 10 LSE's in neutral posture and with postural cueing. Percent maximum voluntary isometric contraction of L5 DM and T12 LT, and ratios of activation (DM/LT) were analyzed. There was a significant main effect for posture on DM activation (p 0.001), indicating greater activation levels during exercises performed with postural cueing vs. neutral posture. LT activation did not increase significantly with postural cueing. Following a significant 1-way repeated measures ANOVA (p = 0.034) for the postural cueing condition, pairwise comparisons demonstrated significantly higher DM/LT activation ratios for prone leg lift, variable-angle Roman chair at 15°, bridging, and bilateral arm and leg lift. These results suggest postural cueing can be used across a range of LSE intensities to increase DM activation without a significant increase in LT activation in patients with chronic or recurrent LBP.

BACKGROUND CONTEXT Most osteoporotic vertebral compression fractures (OVCFs) are treated conservatively; however, in some patients, progressive vertebral body collapse leads to spinal deformity and cord compression. These complications are strongly associated with impaired performance activities of daily living and a poor quality of life. PURPOSE To identify the role of the paraspinal muscle as a risk factor for progressive vertebral body collapse in patients with OVCF. STUDY DESIGN This was a retrospective observational study. PATIENT SAMPLE Fifty-five consecutive patients with OVCF who were treated conservatively from January 2018 to June 2020 in a single spine center and had a minimum follow-up of 6 months. OUTCOME MEASURES A lateral plain radiograph in a neutral posture was taken when the patient was first diagnosed and at 1, 3, and 6 months after the first diagnosis. Vertebral height was measured at the point of maximal collapse of the affected vertebral body; vertebral collapse (%) was also measured. The cross-sectional area (CSA) and fatty degeneration of the paraspinal muscle were measured using the open-source software Image J. The visual analogue scale (VAS) scores were collected at the time of initial fracture diagnosis and at 1, 3, and 6 months. METHODS The clinical and radiological data were analyzed. In the L4–5 intervertebral disc level, axial T2-weighted magnetic resonance imaging was used to measure the CSA and fatty degeneration of the paraspinal muscles. Correlation and multiple regression analyses were performed to analyze the risk factors associated with progressive vertebral body collapse. RESULTS The vertebral collapse difference was strongly associated with paraspinal muscle fatty degeneration (r=0.684, p=.000) and body mass index (r=0.300, p=.026). Multiple linear regression analysis demonstrated that the risk factor for progression of vertebral collapse was paraspinal muscle fatty degeneration (β=0.724, p=.000). There was a statistically significant correlation between the progression in vertebral collapse and VAS score at 3 (r=0.402, p=.002) and 6 months (r=0.604, p=.000). CONCLUSIONS In patients with OVCF, fatty degeneration of the paraspinal muscle was a predictive factor for progressive vertebral body collapse. This study suggests that more attention should be paid to patients with paraspinal sarcopenia among those with OVCFs.

Introduction The six-item Foot Posture Index (FPI-6) was previously developed as an assessment tool to measure the posture of the foot across multiple segments and planes. It was derived from a criterion-based observational assessment of six components of each foot during static standing. The association between abnormal foot posture and musculoskeletal injuries remains unclear and is in of need further exploration. Hypothesis/Purpose The purpose of this study was to assess the association between foot biomechanics and self-reported history of musculoskeletal pain or injury. Study Design Retrospective, cross-sectional study of collegiate football players at the U.S. Naval Academy. Materials and Methods For each athlete, data were recorded on height, weight, self-reported history of pain or injury, and foot posture, which was measured using a FPI-6 with each item measuring the degree of pronation/supination. The primary outcome was each athlete’s maximum deviation from neutral posture across the six-item index (FPImax). The prespecified primary analysis used generalized linear models to measure the association between FPImax and self-report history of pain or injury. Exploratory analyses measured the association using penalized regression (L1-norm) and a type of tree-based ensemble known as extreme gradient boosting (XGBoost). Results Data were collected on 101 athletes, 99 of whom had sufficient body mass index (BMI) data to be included for analysis. Among the 99 athletes, higher FPImax was associated with a prior history of musculoskeletal pain (odds ratio [OR] 1.15, 95% confidence interval [CI] 0.97 to 1.35), although the sample size was too small for the association to be significant with 95% CI (P = .107). FPImax was not associated with a history of knee injury/pain (OR 0.98, 95% CI 0.83 to 1.15, P = .792), nor with a history of ankle/foot injury or pain (OR 1.04, 95% CI 0.90 to 1.21, P = .599). From the L1-penalized model, the FPI components with the strongest linear associations were the L6, R2, R1-squared, and FPImax. From the XGBoost model, the most important variables were FPItotal, BMI, R1, and R2. Conclusions The U.S. Naval Academy football players whose foot postures deviated from neutral were more likely to have reported a previous history of musculoskeletal pain. However, this deviation from normal was not strongly associated with a specific history of pain or injury to the knee, ankle, or foot. Clinical Relevance The information ascertained from this study could be used to better inform clinicians about the value of the FPI in predicting or mitigating injuries for varsity football athletes.

Objective Spinal‐muscle morphological differences between weight‐bearing and supine postures have potential diagnostic, prognostic, and therapeutic applications. While the focus to date has been on cervical and lumbar regions, recent findings have associated spinal deformity with smaller paraspinal musculature in the thoracic region. We aim to quantitatively investigate the morphology of trapezius (TZ), erector spinae (ES) and transversospinalis (TS) muscles in upright postures with open upright MRI and also determine the effect of level and posture on the morphological measures. Methods Six healthy volunteers (age 26 ± 6 years) were imaged (0.5 T MROpen, Paramed, Genoa, Italy) in four postures (supine, standing, standing with 30° flexion, and sitting). Two regions of the thorax, middle (T4‐T5), and lower (T8‐T9), were scanned separately for each posture. 2D muscle parameters such as cross‐sectional area (CSA) and position (radius and angle) with respect to the vertebral body centroid were measured for the three muscles. Effect of spinal level and posture on muscle parameters was examined using 2‐way repeated measures ANOVA separately for T4‐T5 and T8‐T9 regions. Results The TZ CSA was smaller (40%, P = .0027) at T9 than at T8. The ES CSA was larger at T5 than at T4 (12%, P = .0048) and at T9 than at T8 (10%, P = .0018). TS CSA showed opposite trends at the two spinal regions with it being smaller (16%, P = .0047) at T5 than at T4 and larger (11%, P = .0009) at T9 than at T8. At T4‐T5, the TZ CSA increased (up to 23%), and the ES and TS CSA decreased (up to 10%) in upright postures compared to supine. Conclusion Geometrical parameters that describe muscle morphology in the thorax change with level and posture. The increase in TZ CSA in upright postures could result from greater activation while upright. The decrease in ES CSA in flexed positions likely represents passive stretching compared to neutral posture., Sample illustration at level T4 showing post hoc significant for CSA, radius, and angle in upright postures with respect to supine as reference. A, Supine. B, Upright standing. C, Forward flexion. D, Upright sitting

Historically, a neutral posture is recommended for prolonged periods of sitting to avoid pain and reduce risk of injury. However, while evidence exists that those who experience low back pain may find certain postures provocative, there is less evidence to support the idea that “poor” postures are primary pain generators (Slater D, Korakakis V, O’Sullivan P, Nolan D, O’Sullivan K, J Orthop Sports Phys Ther. 49:562–564, 2019). There is a broad spectrum of normal, non-pathological anatomical variation in the spine, and existing spinal curvatures impact postural adaptations. Furthermore, relaxed, comfortable postures will vary between individuals.

Osteoporoza je reumatološka bolest koja uglavnom zahvaća ljude u odmakloj dobi koji su ugroženi nizom drugih kroničnih bolesti. Nakon kardiovaskularnih bolesti vodeći je zdravstveni problem prema Svjetskoj zdravstvenoj organizaciji (WHO). Vježbe kojima primarno jačamo leđa, ramena, noge i bokove najpovoljnije su za osobe s osteoporozom. "Najštetnija vrsta ozljede koja se može dogoditi je prijelom kuka", kaže Rotstein." Jačanje kukova trebao bi biti glavni cilj." Osobe s osteoporozom trebale bi izbjegavati vježbe koje uključuju naginjanje prema naprijed (fleksije ) ili kotrljanje na leđima te bi trebali biti vrlo oprezni u izvođenju vježbi koje uključuju uvijanje kralježnice. Također,trening bi se trebao bazirati na vježbama koje zadržavaju neutral kralježnice. Pilates, s naglaskom na držanje, poravnanje i ravnotežu, kao i cjelovite kretnje tijela, nudi bazu za održavanje tijela u balansu .Pilates također uspostavlja dobru formu za trening s utezima tako da se snaga najbolje prenosi kroz dobro usmjerenu kralježnicu i kukove. Osteoporosis is a rheumatic disease that mainly affects the elderly who are at risk of a number of other chronic diseases. After cardiovascular disease, it is the leading health problem according to the World Health Organization (WHO). Exercises that primarily strengthen the back, shoulders, legs and hips are most beneficial for people with osteoporosis. “The most harmful type of injury that can happen is a hip fracture,” Rotstein says. "Strengthening the hips should be the main goal." People with osteoporosis should avoid exercises that involve leaning forward (flexion) or rolling on their backs and should be very careful when performing exercises that involve twisting the spine. Also, training should be based on exercises that maintain a neutral spine. Pilates, with an emphasis on posture, alignment and balance, as well as complete body movements, offers a base to keep the body in balance. Pilates also establishes good form for weight training so that strength is best transmitted through a well-directed spine and hips.

Purpose The Epic Lift Capacity (ELC) test is used to determine a worker's maximum lifting capacity. In the ELC test, maximum lifting capacity is often determined as the maximum weight lifted without exhibiting a visually appraised "high-risk workstyle." However, the criteria for evaluating lifting mechanics have limited justification. This study applies feature detection and biomechanical analysis to motion capture data obtained while participants performed the ELC test to objectively identify aspects of movement that may help define "high-risk workstyle". Method In this cross-sectional study, 24 participants completed the ELC test. We applied Principal Component Analysis, as a feature detection approach, and biomechanical analysis to motion capture data to objectively identify movement features related to biomechanical exposure on the low back and shoulders. Principal component scores were compared between high and low exposure trials (relative to median exposure) to determine if features of movement differed. Features were interpreted using single component reconstructions of principal components. Results Statistical testing showed that low exposure lifts and lowers maintained the body closer to the load, exhibited squat-like movement (greater knee flexion, wider base of support), and remained closer to neutral posture at the low back (less forward flexion and axial twist) and shoulder (less flexion and abduction). Conclusions Use of feature detection and biomechanical analyses revealed movement features related to biomechanical exposure at the low back and shoulders. The objectively identified criteria could augment the existing scoring criteria for ELC test technique assessment. In the future, such features can inform the design of classifiers to objectively identify "high-risk workstyle" in real-time.

Background Posture variations have been repeatedly linked to shoulder kinematics, strength, range of motion, and rotator cuff diseases. However, to our knowledge, no study has yet examined their possible link with shoulder pain provocation and pain levels during clinical shoulder tests. Objective The objective was to examine whether changing posture while sitting modifies pain provocation and pain level during performance of 3 clinical shoulder tests in participants with shoulder pain and rotator cuff degenerative tears (RCDTs). Methods Seventy individuals were allocated into 2 groups by an experienced physical therapist: 35 participants with symptomatic shoulders and RCDT diagnosed by ultrasound (tear size = 1.0 +/- 0.5 cm) and 35 control participants with no symptoms in the upper limb. All participants were tested by a second physical therapist for pain provocation (yes/no) and pain level (visual analog scale) using 3 common clinical shoulder tests: the Neer, the Hawkins-Kennedy, and the empty can while sitting in a neutral, slouched, and upright posture. Shoulder muscle forces were examined by a hand-held dynamometer for possible correlations only in the neutral posture. All participants were asked to fill out the quick DASH (disabilities of the arm shoulder and hand) questionnaire. Results In the symptomatic group, all 3 clinical tests demonstrated similar pain provocation (100% repeatability) and pain level in all 3 sitting postures (visual analog scale scores 3.7–4.4). Muscle force mean ranges of the study groups were 4.4 to 7 kg and, in the control group, 6 to 10.5 kg. No correlations were found between age, body mass index, shoulder pain, hand dominance, onset of symptoms, severity, and tear size with any of the dependent variables. Conclusions Changing posture while sitting did not directly affect pain provocation and pain levels during performance of 3 clinical shoulder tests in participants with shoulder pain and RCDTs.

Postural changes induce changes in chest wall kinematics and eventually pulmonary function, and affect chest wall shape and chest motion. This study aimed to examine the effects of postural change on changes in the chest wall during respiratory muscle training. Using a repeated measures design, this study followed 13 healthy adults (13 men; mean age, 23.73 years). All participants performed four postures (neutral, full trunk rotation, half-range trunk rotation, and lateral ribcage shift postures) during respiratory muscle training. The chest wall movement during the four postures was measured using a three-dimensional motion-analysis system during respiratory muscle training. Surface electromyography data were collected from the diaphragm and sternocleidomastoid muscles, and the asymmetric ratio of muscle activation was calculated based on the collected data. The chest wall movements of the upper costal and middle costal region were greater in the neutral posture than in the full rotation, half rotation, and lateral ribcage shift postures (P

Harvesting palm oil crops involve different risk factors that decrease workers’ safety and physical integrity. This paper compares stress on the lower back when using the conventional tool and a new cutting system for cutting bunches. The biomechanical analysis is carried out using simulations generated by JACK Siemens software. The study found a 95.97% reduction of intradiscal compression (L4/L5) when cutting bunches and showed that pressure on all joints was reduced, in certain cases, such as the back and elbow, by up to 100%. That is, when cutting using the new system, the worker maintains a neutral posture of the spine. The new design comprises a point of support on which the tool rests and means that workers only have to direct the blade. Future studies should compare both tools in terms of productivity while preserving the ergonomic characteristics. Resumen En los cultivos de aceite de palma se presentan diferentes factores de riesgo que disminuyen la seguridad y la integridad física de los trabajadores. Este trabajo compara el estrés de la espalda baja durante el corte de racimos, entre la herramienta convencional y un nuevo sistema de corte, a partir de un análisis biomecánico utilizando Jack Siemens. El estudio encontró una reducción del 95.97% en la compresión intradiscal (L4/L5) durante la actividad de corte. Asimismo, el estudió muestra que se disminuyó las demandas articulares, en la espalda y codo hasta en un 100%, es decir, que durante la actividad con el nuevo sistema diseñado, el agricultor mantiene una postura de espalda neutral. Este nuevo diseño consta de un punto de apoyo, en donde la herramienta descansa y por tanto, solo se debe dar dirección al corte. Los estudios futuros deberían comparar ambas herramientas en términos de productividad, pero conservando las características ergonómicas.

Cervical spine injuries often happen in dynamic environments (e.g., sports and motor vehicle crashes) where individuals may be moving their head and neck immediately prior to impact. This motion may reposition the cervical vertebrae in a way that is dissimilar to the upright resting posture that is often used as the initial position in cadaveric studies of catastrophic neck injury. Therefore our aim was to compare the "neutral" cervical alignment measured using fluoroscopy of 11 human subjects while resting in a neutral posture and as their neck passed through neutral during the four combinations of active flexion and extension movements in both an upright and inverted posture. Muscle activation patterns were also measured unilaterally using surface and indwelling electromyography in 8 muscles and then compared between the different conditions. Overall, the head posture, cervical spine alignment and muscle activation levels were significantly different while moving compared to resting upright. Compared to the resting upright condition, average head postures were 6-13° more extended, average vertebral angles varied from 11° more extended to 10° more flexed, and average muscle activation levels varied from unchanged to 10% MVC more active, although the exact differences varied with both direction of motion and orientation. These findings are important for ex vivo testing where the head and neck are statically positioned prior to impact - often in an upright neutral posture with negligible muscle forces - and suggest that current cadaveric head-first impact tests may not reflect many dynamic injury environments.

This study evaluated between-session reliability of opto-electronic motion capture to measure trunk posture and three-dimensional ranges of motion (ROM). Nineteen healthy participants aged 24–74 years underwent spine curvature, pelvic tilt and trunk ROM measurements on two separate occasions. Rigid four-marker clusters were attached to the skin overlying seven spinous processes, plus single markers on pelvis landmarks. Rigid body rotations of spine marker clusters were calculated to determine neutral posture and ROM in flexion, extension, total lateral bending (left-right) and total axial rotation (left-right). Segmental spine ROM values were in line with previous reports using opto-electronic motion capture. Intraclass correlation coefficients (ICC) and standard error of measurement (SEM) were calculated as measures of between-session reliability and measurement error, respectively. Retroreflective markers showed fair to excellent between-session reliability to measure thoracic kyphosis, lumbar lordosis, and pelvic tilt (ICC = 0.82, 0.63, and 0.54, respectively). Thoracic and lumbar segments showed highest reliabilities in total axial rotation (ICC = 0.78) and flexion-extension (ICC = 0.77–0.79) ROM, respectively. Pelvic segment showed highest ICC values in flexion (ICC = 0.78) and total axial rotation (ICC = 0.81) trials. Furthermore, it was estimated that four or fewer repeated trials would provide good reliability for key ROM outcomes, including lumbar flexion, thoracic and lumbar lateral bending, and thoracic axial rotation. This demonstration of reliability is a necessary precursor to quantifying spine kinematics in clinical studies, including assessing changes due to clinical treatment or disease progression.

BACKGROUND Touch screen computers require significant arm and hand movements. This can result to body discomfort and biomechanical load in users. OBJECTIVES This study was carried out to examine posture and users' discomfort while using touch screen device as compared with mouse-keyboard and touch pad-keyboard. METHODS Twenty three (23) students participated in this experimental study. The subjects completed pre-defined tasks in three 15 min trials by means of touch screen, touch pad-keyboard and mouse-keyboard as input devices. Postural angles were measured by Qualisys motion capture system. Body discomfort was assessed by a 10-cm visual analog scale. Rating scale was employed to assess the perception of subjects on the posture of body parts while utilizing the three devices. RESULTS There was no significant difference in head inclination when using the three types of devices. Nevertheless, the mean of neck (p = 0.005) and trunk (p

Background The need for posterior longitudinal ligament (PLL) resection during cervical total disc arthroplasty (TDA) has been debated. The purpose of this laboratory study was to investigate the effect of PLL resection on cervical kinematics after TDA. Methods Eight cadaveric cervical spine specimens were tested in flexion-extension (FE), lateral bending (LB), and axial rotation (AR) to moments of ±1.5 Nm. After testing the intact condition, anterior C5-C6 cervical discectomy was performed followed by PLL resection and implantation of a compressible, 6-degrees-of-freedom disc prosthesis (M6-C, Spinal Kinetics Inc, Sunnyvale, California). Next, a second prosthesis was implanted at C6-C7 with PLL intact. Finally, the C6-C7 PLL was resected while the disc prosthesis remained in place. Segmental range of motion (ROM) and stiffness in the high flexibility zone around the neutral posture were analyzed using repeated measures ANOVA. Results At C5-C6, following TDA and PLL resection, FE, LB, and AR ROMs decreased significantly. Anterior and posterior disc height, segmental lordosis, and flexion stiffness increased significantly. At C6-C7, TDA with the PLL intact resulted in a significant increase in anterior disc height and segmental lordosis with no change in posterior disc height. FE, LB, and AR ROMs all decreased significantly, while flexion stiffness increased significantly compared to intact. PLL resection at C6-C7 did not result in a notable change compared to TDA with PLL intact. At the same level, flexion stiffness decreased following PLL resection compared to TDA with a value closer to intact. Two-level TDA (C5-C7) with PLL resection did not result in a loss of segmental stability. Conclusion PLL resection did not significantly affect motion segment kinematics following cervical TDA using a prosthesis with inherent stiffness. Motion segment stiffness loss after PLL resection can be compensated for by a TDA design that can provide resistance to angular motion.

Neck muscle size and strength have been linked to lower injury risk and reduced pain. However, prior findings have been inconclusive and have failed to clarify whether there are sex differences in neck muscle size-strength relationships. Such differences may point to an underlying cause for the reported sex difference in neck pain prevalence. Thirty participants (13 males, 17 females) who underwent neck strength testing and MR imaging were analyzed. Strength was measured in three conditions that differed in posture and exertion direction. Muscle size was quantified by three metrics: anatomical cross-sectional area (ACSA), muscle volume (MV), and an estimate of physiological cross-sectional area—reconstruction-based cross-sectional area (RCSA). Inter-posture strength correlations, muscle size-strength correlations, and sex differences were analyzed with linear regression. Males were approximately 65% stronger and had significantly larger muscles. Strength varied significantly across postures, but only female strength values for different postures were significantly correlated. Observed in males only, the sternocleidomastoid (SCM) was a strong predictor of flexion strength in the neutral posture while the anterior scalene (AS) was more involved in the extended. No extensor’s size was significantly linked to extension strength. A greater amount of force variation is unexplained by muscle size alone in females than in males. Males and females exhibited distinct size-strength relationships, highlighting the need for sex-specific models and analyses and the greater potential effect of non-morphometric factors on force generating capacity in females. No advantage of one muscle size metric over another in strength prediction was evidenced.

While using their smartphone, users tend to adopt awkward neck and shoulder postures for an extended duration. Such postures impose the risk of MSDs on those body parts. Numerous studies have been undertaken to examine neck posture; however, few studies have investigated shoulder postures. This study examined various shoulder postures during smartphone use and their effect on neck and shoulder kinematics, muscle loading, and neck/shoulder discomfort. Thirty-two asymptomatic young adult smartphone users randomly performed texting tasks for 3 min at four different shoulder flexion angles (15°, 30°, 45°, and 60°), while maintained a neck posture in the neutral position (0° neck flexion angle). Measures were taken of neck and shoulder muscle activity of the cervical erector spinae (CES), anterior deltoid (AD), upper trapezius (UT) and lower trapezius (LT), and kinematic data (angle, distance and gravitational moment). Results showed AD and LT muscle activity significantly increased when the shoulder flexion angle increased with an opposite effect on CES and UT. A recommended shoulder posture was identified as 30° flexion, as this yielded the best compromise between activation levels of the four muscles studied. This angle also induced the lowest neck/shoulder discomfort score. The findings suggest smartphone users hold their device at approximately 30° shoulder flexion angle with their neck in a neutral posture to reduce the risk of shoulder and neck musculoskeletal disorders when smartphone texting. Relevance to industry: Smartphone use in the manufacturing and service industries is an integral part of work and useful means of communication tool. Awkward postures during extensive smartphone use impose an increased risk of both neck and shoulder musculoskeletal disorders. Shoulder flexion angles need consideration when making recommendations about safe work postures during smartphone use. Refereed/Peer-reviewed

Wrist rotations about one wrist axis (e.g. flexion/extension) can affect the strength about another wrist axis (e.g. radial/ulnar deviation). This study used a musculoskeletal model of the distal upper extremity, and an optimization approach, to quantify the interaction effects of wrist flexion/extension (FE), radial/ulnar deviation (RUD) and forearm pronation/supination (PS) on wrist strength. Regression equations were developed to predict the relative changes in strength from the neutral posture, so that the changes in strength, due to complex and interacting wrist and forearm rotation postures, can be incorporated within future ergonomics assessments of wrist strength.

The ongoing controversy centered on neck posture and function in sauropod dinosaurs is misplaced for a number of reasons. Because of an absence of pertinent data it is not possible to accurately restore the posture and range of motion in long necked fossil animals, only gross approximations are possible. The existence of a single "neutral posture" in animals with long, slender necks may not exist, and its relationship to feeding habits is weak. Restorations of neutral osteological neck posture based on seemingly detailed diagrams of cervical articulations are not reliable because the pictures are not sufficiently accurate due to a combination of illustration errors, and distortion of the fossil cervicals. This is all the more true because fossil cervical series lack the critical inter-centra cartilage. Maximum vertical reach is more readily restorable and biologically informative for long necked herbivores. Modest extension of 10° between each caudal cervical allowed high shouldered sauropods to raise the cranial portion of their necks to vertical postures that allowed them to reach floral resources far higher than seen in the tallest mammals. This hypothesis is supported by the dorsally extended articulation of the only known co-fused sauropod cervicals. Many sauropods appear to have been well adapted for rearing in order to boost vertical reach, some possessed retroverted pelves that may have allowed them to walk slowly while bipedal. A combination of improved high browsing abilities and sexual selection probably explains the unusually long necks of tall ungulates and super tall sauropods. Anat Rec, 2017. © 2017 Wiley Periodicals, Inc. Anat Rec, 300:1802-1825, 2017. © 2017 Wiley Periodicals, Inc.

Background Musculoskeletal disorders (MSDs) can be prevented by avoiding trauma caused by poor posture, compression, force, and repetition. Neutral postures are recommended to avoid MSDs. Objective This study introduces Mouse With Your Arm™ (MWYA) methodology which promotes sitting back in a chair, using the chair's armrest for forearm support at relaxed elbow height, matching surface and armrest height, and keeping the mouse on the surface edge. This position allows optimal task chair use, facilitates movement and neutral postures, avoids compression and contact stress, and is effective in mitigating MSDs. Method MWYA was applied and measured in the field for more 23 years providing over 3,500 individualized assessments to integrate a participant's unique characteristics, reported health concerns, tasks, tools, and environment to achieve and sustain whole-body neutral and comfortable working postures. Results Previous research has consistently recommended use of forearm support by a desk, apparatus, or wrist rest, and resulted in non-neutral, static postures and measured health consequences. By using armrests for support, MWYA avoids the potential of MSDs as can be caused by these previously endorsed postures. Conclusion By applying the five MWYA principles, computer users comprehend neutral posture and put forth the effort essential to creating healthy human computer relationships.

Background Previous research has shown that anxiety syndromes are highly prevalent among university students. Effective treatments are needed to reduce the burden of anxiety in this population. Powerful postures have been found to impact affective states, as well as interoception (i.e. the ability to perceive inner bodily signals). However, no previous study has compared the effects of powerful- and neutral postures in regards to anxiety and interoceptive ability. Methods The first part of the study measured the single-session effect of adopting powerful- vs. neutral postures on students' (n = 57) interoceptive ability and state anxiety. The second part of the study measured the effect of adopting powerful or neutral postures twice daily for two weeks, on individuals' interoceptive ability and trait anxiety. Results State anxiety decreased in both conditions whereas interoceptive accuracy only increased in the power posing condition after a single session. Interoceptive accuracy increased in both groups after two weeks of training. Limitations The study included no comparison to a condition where individuals adopted their natural (i.e. usual) bodily posture. Conclusions Embodiment interventions that include elements of adopting an open or expansive bodily posture whilst maintaining a self-focus, can help to reduce state anxiety and improve interoceptive accuracy in student populations. Power posing does not seem to be superior to holding a neutral posture to improve interoceptive accuracy or anxiety. One reason therefore could be that both conditions include the manipulation of self-focus and a postural change that diverges from individuals' normal posture., publishedVersion

OBJECTIVES The primate talus is known to have a shape that varies according to differences in locomotion and substrate use. While the modern human talus is morphologically specialized for bipedal walking, relatively little is known on how its morphology varies in relation to cultural and environmental differences across time. Here we compare tali of modern human populations with different subsistence economies and lifestyles to explore how cultural practices and environmental factors influence external talar shape. MATERIALS AND METHODS The sample consists of digital models of 142 tali from 11 archaeological and post-industrial modern human groups. Talar morphology was investigated through 3D (semi)landmark based geometric morphometric methods. RESULTS Our results show distinct differences between highly mobile hunter-gatherers and more sedentary groups belonging to a mixed post-agricultural/industrial background. Hunter-gatherers exhibit a more "flexible" talar shape, everted posture, and a more robust and medially oriented talar neck/head, which we interpret as reflecting long-distance walking strictly performed barefoot, or wearing minimalistic footwear, along uneven ground. The talus of the post-industrial population exhibits a "stable" profile, neutral posture, and a less robust and orthogonally oriented talar neck/head, which we interpret as a consequence of sedentary lifestyle and use of stiff footwear. DISCUSSION We suggest that talar morphological variation is related to the adoption of constraining footwear in post-industrial society, which reduces ankle range of motion. This contrasts with hunter-gatherers, where talar shape shows a more flexible profile, likely resulting from a lack of footwear while traversing uneven terrain. We conclude that modern human tali vary with differences in locomotor and cultural behavior.

Introduction: Mattresses need to provide enough support to keep spinal alignment close to a neutral posture, whilst minimising muscle activity and providing optimum pressure relief. There is limited evidence to sug­gest that a 'one size fits all' mattress provides the appropriate support for individuals with diverse body shapes, so a greater understanding of how different mattresses affect the human body is key. By having a more objective approach to choosing a mattress an individual may have an improved quality of sleep. \ud Materials and methods: A ten-camera infrared movement analysis sys­tem recorded the movement of retro-reflective markers placed on the Upper-Mid Thoracic, Mid-Lower Thoracic, Lower Thoracic-Upper Lumbar, Upper-Lower Lumbar and Lower Lumbar-Pelvic areas of the spine. A static image of the spine was taken in a standing position and was used to define each individual's neutral posture. Deviations away from this neutral po­sition were assessed under three different conditions in side lying. Three visually identical mattresses were tested, internally each mattress con­tained a different firmness of spring unit (soft, medium, firm) with an identical gel foam comfort layer. In addition, height, weight, shoulder width and hip circumference measurements were taken to determine differences in body types. \ud Results: Spinal alignment was assessed on 59 healthy participants and no significant differences were seen between the different mattress config­urations. However, further analysis showed significant differences in spi­nal alignment between the different mattress conditions within different body shape subgroups. Subgroups were defined using body weight, height, BMI, shoulder width and hip circumference. Those with a higher body weight had a more neutral spinal alignment when on a firmer mattress, whereas those with a lower body weight were better suited to a softer mattress. Shorter people were better aligned on a softer mattress, and a medium mattress kept the spine in a more neutral position amongst taller people. There were no differentiating factors between shoulder width or BMI groups. However, those with a larger hip circumference had signifi­cantly greater spinal deviations when on a softer mattress. implying that a softer mattress should be avoided by this subgroup. \ud Conclusions: This study suggests that a ·one size fits all' approach to mattresses may not be appropriate. Contrasting body types need different levels of support to improve overall spinal alignment, allowing the inter­vertebral disc to re-hydrate, and spinal muscles to relax throughout the night. The use of simple anthropometric measurements could make the selection of the most appropriate mattress easier for the general public. Acknowledgements: This is part of an Innovate UK Knowledge Transfer Partnership between the University of Central Lancashire and Silentnight Group Ltd.

Neck muscle activation is increasingly important for accurate prediction of occupant response in automotive impact scenarios and occupant excursion resulting from active safety systems such as autonomous emergency braking. Muscle activation and optimization in frontal impact scenarios using computational Human Body Models have not been investigated over the broad range of accelerations relevant to these events. This study optimized the muscle activation of a contemporary finite element model of the human head and neck for human volunteer experiments over a range of frontal impact severities (2 g to 15 g). The neck muscles were grouped as flexors and extensors, and optimization was undertaken for each group based on muscle activation level and activation time. The boundaries for optimization were defined using data from the literature and a preliminary parametric study. A linear polynomial method was used to optimize the model head kinematics to the volunteer experiments for each impact severity. The optimized models predicted muscle activation to increase with higher impact severities, and improved the average cross-correlation by 35% (0.561–0.755) relative to the Maximum Muscle Activation (MMA) scheme in the original model. Importantly, a newly proposed Cocontraction Muscle Activation (CMA) scheme for maintaining the head in a neutral posture provided a 23% on average improvement in correlation compared to the MMA scheme. In conclusion, this study identified a new scheme to obtain more accurate response kinematics across multiple impact severities in computational Human Body Models as well as contributing to the understanding of muscle influence during frontal impact scenarios.

Background:Neck disorder is a common complaint in computer users which affects the task performance and fatigue. Several studies confirmed the relation between neck discomfort and working with a computer. But focusing on the root risk factors inducing neck discomfort can be applied for taking preventive measures and improving workstation design. So, the main purpose of this study was the neck posture analysis in computer users and identifying the related risk factors. Methods:This descriptive-analytical study was performed in 2018 on 169 administrative staff in one of the governmental hospitals in Qom. A researcher-made questionnaire was used to investigate neck discomfort and related risk factors. To determine the angle of the neck, photographic analysis method was used. Finally, SPSS software version 22 and appropriate statistical tests including the logistic regression model, two independent t-test, and chi-square test in contingency tables were used to determine the relationship between individual parameters and workstation with neck angles and neck pain. Results:The results showed that two factors of the height (p= 0.023) and the gender (p= 0.012) had a direct statistically significant association with neck disorder statistically. In addition, the anthropometric dimensions, monitor height from desk level was positively correlated with neck discomfort but sitting elbow to eye height was negatively correlated with neck discomfort (p

The use of hand tools in industry is one of the many risky issues for musculoskeletal disorders. Working postures during handling tools assumed may be reiterated several times a day, every day for several years and can be predicted to affect the musculature of the workers. Using physiological demands to assess coordinated posture and anthropometry in manual handling tools has not received much attention in literature. Therefore, the aim of this research is to study the effects of combined postures of trunk and shoulder besides the individual’s anthropometry on heart rate in vertical drilling task. Ten male students participated in this experiment and ANOVA (Analysis of variance) was used to analyse the data. The results showed that shoulder flexion and trunk inclining forward have a significant effect on heart rate (P < 0.01). Also, the anthropometric in terms of individual’s weight and max grip strength has a negative correlation with heart rate (R2 = 0.46 and 0.13 respectively).

Electromyography (EMG)-based interfaces are trending toward continuous, simultaneous control with multiple degrees of freedom. Emerging methods range from data-driven approaches to biomechanical model-based methods. However, there has been no direct comparison between these two types of continuous EMG-based interfaces. The aim of this study was to compare a musculoskeletal model (MM) with two data-driven approaches, linear regression (LR) and artificial neural network (ANN), for predicting continuous wrist and hand motions for EMG-based interfaces. Six able-bodied subjects and one transradial amputee subject performed (missing) metacarpophalangeal (MCP) and wrist flexion/extension, simultaneously or independently, while four EMG signals were recorded from forearm muscles. To add variation to the EMG signals, the subjects repeated the MCP and wrist motions at various upper extremity postures. For each subject, the EMG signals collected from the neutral posture were used to build the EMG interfaces; the EMG signals collected from all postures were used to evaluate the interfaces. The performance of the interface was quantified by Pearson’s correlation coefficient (r) and the normalized root mean square error (NRMSE) between measured and estimated joint angles. The results demonstrated that the MM predicted movements more accurately, with higher r values and lower NRMSE, than either LR or ANN. Similar results were observed in the transradial amputee. Additionally, the variation in r across postures, an indicator of reliability against posture changes, was significantly lower (better) for the MM than for either LR or ANN. Our findings suggest that incorporating musculoskeletal knowledge into EMG-based human-machine interfaces could improve the estimation of continuous, coordinated motion.

Three-dimensional joint angles are most often quantified using Euler Angles. These measures are often easier to interpret if they are reported relative to a reference posture. However, since Euler Angles are not vectors, directly subtracting their values is difficult to justify mathematically. We compared four methods for subtracting a reference posture: the Subtraction Method (SM), directly subtracting the Euler Angles; two variants on the Relative Segment Method (RSM), one aligned to global (gRSM) and one aligned to the distal segment (dRSM), which considers the relative rotation of each segment to the reference posture; and the Relative Joint Method (RJM), which considers the relative rotation of the joint coordinate systems compared to that of the reference posture. One exemplar male subject (height: 175 cm; body mass: 90 kg; age: 27) performed three trials where they extended, laterally bent to the right, and extended while returning to a neutral posture between these movements. Two reference postures were compared: a standing neutral posture, and 90 degrees of flexion. All four methods showed strong agreement when the reference posture was a neutral one (lowest R 2 = 0.971 ). However, when the reference posture was 90 degrees of flexion, both the RJM and gRSM swapped their lateral bend and axial twist measures. Additionally, when the reference posture was oriented 90 degrees from the global coordinate system, the gRSM swapped flexion and lateral bending. Therefore, the RJM, dRSM, and even the SM, are more robust than the gRSM. Either the RJM or dRSM are recommended as it is a compromise between mathematical validity and interpretability, however, the RJM seems to provide more readily interpretable angular velocities. The SM is only a viable approach under very strict conditions and should be avoided.

A wheelchair is usually a source of mobility for people with moderate to severe cerebral palsy, who are unable to walk. They spend long periods of time sitting in their wheelchair, which can affect their head and neck alignment. Opening the seat to back support angle of the wheelchair can modify realignment of body segments and improve posture. Aims: To examine the effect of seat to back support angle adjustments on head, neck, and shoulder postural alignment in people with cerebral palsy. Methods: Nine participants with cerebral palsy who use a wheelchair for mobility sat in a research wheelchair. Sagittal head angle (SHA), cervical angle (CVA), and shoulder angle (SA) from photographs were examined using the Coach's Eye device during three different seat to back support angles of the wheelchair (90°, 100°, 110°). Results: There were significant differences in mean SHA and CVA among the different seat to back support angles (p < .001). However, there was no significant difference in mean SA. Conclusion: Head (SHA) and (CVA) alignment was closest to neutral posture with seat to back support angles set at 110°. Thus, adjusting the wheelchair back support to a 110o would provide the most appropriate sagittal head and cervical angle for this population.

Background The risk of interlaminar passage of a dilator into the cervical spinal canal in minimally invasive approaches is currently unknown. Among the various anthropometric data reported in the literature, there is no report of the interlaminar dimensions in the cervical spine. Objective To report the cervical interlaminar dimensions in neutral, flexion, and extension. Methods A total of 8 spines were sectioned into cervical (C2-T1) segments. Digitized coordinate data defining the locations and movements of chosen anatomic points on the laminar edges at a given spinal level were used to compute the dimensions during a static neutral posture, flexion, and extension positions to mimic the positions during surgery. Interlaminar dimensions were averaged and categorized for each vertebral level and spinal posture. Results Based on the reported measurements, the smallest diameter dilator in commonly used dilator sets has the potential to traverse the interlaminar space at all levels in flexion. In a neutral posture, the average interlaminar distance at C2-3, C6-7, and C7-T1 was still greater than 2.0 mm, the smallest diameter of the initial dilator. The largest interlaminar distance was at C6-7 in flexion (7.68 ± 1.60 mm). Conclusion Because dilators pass directly onto the cervical lamina without visualization of the midline structures, the interlaminar distances have increased relevance in the minimally invasive cervical approaches of foraminotomy and laminectomy. The data in this report demonstrate the theoretical risk of interlaminar passage with small diameter dilators in posterior minimally invasive approaches to the cervical spine.

BACKGROUND CONTEXT Prior data about the modulating effects of lumbar spine posture on facet capsule strains are limited to small joint deviations. Knowledge of facet capsule strain during rotational and translational intervertebral joint motion (ie, large joint deviations) under physiological loading could be useful as it may help explain why visually normal lumbar spinal joints become painful. PURPOSE This study quantified the strain tensor of the facet capsule during rotation and translation range-of-motion tests. STUDY DESIGN/SETTING Strain was calculated in isolated porcine functional spinal units. Following a preload, each specimen underwent a flexion/extension rotation (F/E) followed by an anterior/posterior translation (A/P) range-of-motion test while under a 300 N compression load. METHODS Twenty porcine spinal units (10 C3–C4, 10 C5–C6) were tested. Joint flexion/extension was imposed by applying a ±8 Nm moment at a rate of 0.5°/s, and translation was facilitated by loading the caudal vertebra with a ±400 N shear force at a rate of 0.2 mm/s. Points were drawn on the exposed capsule surface and their coordinates were optically tracked throughout each test. Strain was calculated as the displacement of the point configuration with respect to the configuration in a neutral joint position. RESULTS Compared to a neutral posture, superior-inferior strain increased and decreased systematically during flexion and extension, respectively. Posterior displacement of the caudal vertebra by more than 1.3 mm was associated with negative strains, which was significantly lower than the +4.6% strain observed during anterior displacement (p≥.199). The shear strain associated with anterior translation was, on average, −1.1% compared to a neutral joint posture. CONCLUSIONS These results demonstrate that there is a combination of strain types within the facet capsule when spinal units are rotated and translated. The strains documented in this study did not reach the thresholds associated with nociception. CLINICAL RELEVANCE The magnitude of flexion-extension rotation and anterior-translation may glean insight into the facet capsule deformation response under low compression (300 N) loading scenarios. Further, intervertebral joint motion alone, even under low compression loading, does not appear to initiate a clinically relevant pain response in the lumbar facet capsule of a nondegenerated spinal joint.

With increased tablet ownership in the United States comes increased levels of neck flexion compared to desktop or laptop computer use, and these neck postures have been linked to increases in neck pain. Importantly, tablet viewing postures can be achieved in multiple ways and could be determined by the morphology of the individual and/or other extraneous factors. In this study, we aim to preliminarily evaluate how neck postures vary during tablet use among individuals and link this variation to other factors such as sex, height, weight, presence/absence of temporomandibular joint disorder (TMD), and morphology of the head and neck. We analyzed two-dimensional landmarks placed on lateral-view radiographs of 22 participants (10 female and 12 male) seated in neutral, upright, fully flexed, semi-reclined, and reclined postures. We utilize geometric morphometric techniques, which are advantageous for evaluating shape variation and have not been extensively applied to biomechanical analyses. We found skeletal morphology to be significantly related to sex and height in all but the neutral posture (P < 0.05), and weight was marginally significantly related to shape in the semi-reclined posture (P = 0.047). Morphologically, male participants exhibited more flexion at the articulatio atlantooccipitalis than females, and females showed greater mandibular protrusion than males, although this result is likely related to height. No relationship was found between posture and TMD. This research establishes a framework for future work that uses geometric morphometric analyses to evaluate how neck postures vary in relation to TMD. Clin. Anat. 32:1061-1071, 2019. © 2019 Wiley Periodicals, Inc.

Background: The positive findings from our previous studies, which revealed the link between postural and gait patterns in children with unilateral cerebral palsy (CP) were very encouraging for recognition this relationship in children with bilateral cerebral palsy (CP). Therefore, the objective of this study was to evaluate whether different gait patterns corresponding to postural patterns in children with bilateral CP could be statistically significant according to a cluster analysis. Methods: Fifty-eight participants with bilateral CP and 45 matched children with typical growth and development. The participants walked barefoot along a treadmill at their own pace. Three-dimensional kinematic data were collected using the Measuring System for Motion Analysis. To characterize gait patterns, the Gillette Gait Index (GGI) and its 16 distinct gait parameters were used. The participants were divided into four subgroups according to their postural patterns. Results: A cluster analysis revealed 4 gait patterns corresponding to postural patterns: (1) normal gait pattern corresponded to neutral posture; (2) balanced gait pattern corresponded to balanced posture; (3) lordotic gait pattern corresponded to lordotic postural pattern; (4) swayback gait pattern corresponded to backward-leaning posture. There were significant differences in mean GGI and various clusters in the 8 GGI gait parameters: cadence, mean pelvic tilt; mean pelvic rotation, minimum hip flexion, peak hip abduction in swing; knee flexion at initial contact, and peak dorsiflexion in stance. Conclusion: Our results showed that gait discrepancies among children with bilateral CP were not simply a result of lower limb kinematic deviations in the sagittal plane. Information on different gait patterns could improve early therapy in children with bilateral CP before abnormal gait patterns are fully established.

Total wrist arthroplasty (TWA) designs suffer from relatively high complication rates when compared to other arthroplasties. Understanding the contact pattern of hip and knee replacement has improved their design and function; however, the in vivo contact pattern of TWA has not yet been examined and is thus the aim of this study. We hypothesized that the center of contact (CoC) is located at the geometric centers of the carpal component and radial component in the neutral posture and that the CoC moves along the principal arcs of curvature throughout primary anatomical motions. Wrist motion and implant kinematics of six patients with the Freedom® total wrist implant were studied during various tasks using biplanar videoradiography. The location of the CoC of the components was investigated by calculating distance fields between the articular surfaces. We found the CoC at the neutral posture was not at the geometric centers but was located 3.5 mm radially on the carpal component and 1.2 mm ulnarly on the radial component. From extension to flexion, the CoC moved 10.8 mm from dorsal to volar side on the carpal component (p 0.0001) and 7.2 mm from volar to dorsal on the radial component (p = 0.0009). From radial to ulnar deviation, the CoC moved 12.4 mm from radial to ulnar on the carpal component (p 0.0001), and 5.6 mm from ulnar to radial on the radial component (p = 0.009). The findings of this study may eventually improve TWA success by advancing future designs through a more accurate understating of their kinematic performance in vivo.

People in wheelchairs spend a long time in the sitting position and often incur alignment problems resulting in neck and back pain. This study: (1) assessed the validity/reliability of Coach's Eye (CE) smart device application, (2) examined the effect of seat to back support angle adjustments on head, neck, and shoulder posture in the sitting position, and (3) compared changes in cervical rotation at each back support angle. Abled subjects sat in a wheelchair with back support angles positioned at 90°, 100°, and 110°. CE, as well as ImageJ software, was used to analyze three angles: sagittal head angle (SHA), cervical angle (CVA), and shoulder angle (SA). There were highly significant differences for CVA and SA (p

Whereas in the past dental stools typically facilitated a 90° hip angle, a number of currently available alternative designs allow for a more extended hip posture. The present study investigated the influence of different stool types on muscle activity and lumbar posture. Twenty five participants completed a simulated dental procedure on a standard stool, a saddle and the Ghopec. The latter stool comprises a seat pan consisting of a horizontal rear part for the pelvis and an inclinable sloping down front part for the upper legs, with a vertically and horizontally adjustable back rest. Lumbar posture was most close to neutral on the Ghopec, whereas sitting on a standard/saddle stool resulted in more flexed/extended postures respectively. Sitting with a 90° angle (standard stool) resulted in higher activation of back muscles while sitting with a 125° angle (saddle and Ghopec) activated abdominal muscles more, although less in the presence of a backrest (Ghopec). To maintain neutral posture during dental screening, the Ghopec is considered the most suitable design for the tasks undertaken.

Fatigue-failure in low back tissues is influenced by parameters of cyclic loading. Therefore, this study quantified the effect of loading rate and frequency on the number of tolerated compression cycles. Energy storage and vertical deformation were secondarily examined. Thirty-two porcine spinal units were randomly assigned to experimental groups that differed by loading rate (4.2 kN/s, 8.3 kN/s) and loading frequency (0.5 Hz, 1 Hz). Following preload and range-of-motion tests, specimens were cyclically loaded in a neutral posture until fatigue-failure occurred or 10800 cycles were tolerated. Macroscopic dissection was performed to identify the fracture morphology, and measurements of energy storage and vertical displacement were calculated throughout the specimen lifespan (1%, 10%, 50%, 90%, 99%). Given the differences in compression dose-force-time integral-between experimental conditions, the number of sustained cycles were assessed following linear and nonlinear dose-normalization via correction factors calculated from existing risk-exposure approximations. Without dose-normalization, an 8.3 kN/s loading rate and 0.5 Hz loading frequency reduced the fatigue lifetime by 3541 and 5977 cycles, respectively (p 0.001). Linear and nonlinear dose-normalization resulted in a significant rate × frequency interaction (p 0.001). For a 1 Hz loading frequency, the number of sustained loading cycles did not differ between loading rates (p

The number of home office workers sitting for many hours is increasing. The sensor chair is tracking users’ sitting behavior which the help of pressure sensors and tries to avoid wrong postures which may cause diseases. The system provides live monitoring of the pressure distribution via web interface, as well as sitting posture prediction in real time. Posture analysis is realized through machine learning algorithm using a decision tree classifier that is compared to a random forest. Data acquisition and aggregation for the learning process happens with a mobile app adding users biometrical data and the taken sitting posture as label. The sensor chair is able to differentiate between an arched back, a neutral posture or a laid back position taken on the chair. The classifier achieves an accuracy of 97.4% on our test set and is comparable to the performance of the random forest with 98.9%.

Objectives To compare three different exercises for dysphagia to see if they had effects on tongue strength. Design Thirty-one healthy volunteers were randomly divided into three groups. One group (G1, n = 10) performed 24 sets of five repetitions with 30 s rest with the target level set at 80 % of one repetition maximum using Iowa Oral Performance Instrument (IOPI) per day. Another group (G2, n = 10) performed exercise which was consisted of forceful swallow of 5 mL of water in a neutral posture every 10 s for 20 min per day. The other group (G3, n = 11) performed 5 mL of water swallowing exercise in chin-down posture every 10 s for 20 min per day. A total of 12 sessions in four weeks were performed in all groups. Blinded lingual strength measures (maximal isometric pressure) were obtained using IOPI before training and at four weeks after training for the three groups. Results After four weeks of training, measures of tongue strength were increased significantly in all groups. However, there was no significant difference in strength increment among groups [average increase in strength ± standard deviation (% of initial value): G1, 10.3 ± 10.4 %; G2, 8.7 ± 9.45 %; G3, 9.9 ± 12.6 %, p = 0.825]. Conclusions Regardless of the type, tongue strengthening exercises had good effects in improving the swallowing function with equal superiority.

The purpose of this study was to determine the muscle activity of upper trapezius muscle of different head posture at standing and sitting positions by using surface electromyography (sEMG) signals. This tool may be a non-invasive technique that enables the analysis of muscle activity. Human’s head posture is significant part of human body and have a big role to analyze posture of human body. During this approach surface electrodes are employed to record surface electromyography (sEMG) signals of head posture at different angles. It is discovered that the muscle action of upper trapezius at both standing and sitting position is higher at 60 degree of head pose, whereas it’s lower just in case of zero degree that may be a neutral posture of head. It was also found that the muscle activity at standing position is higher than that of sitting position and in the result right trapezius muscle is more activate in standing position than the sitting position. It was also investigated that the muscle activity in standing is higher than that of sitting position. It is suggested that the muscle activity of head posture is lower in neutral position of head.

Altered afferent input from the neck due to fatigue alters upper limb proprioception and is likely to impact upper limb performance accuracy. This study examined the effect of cervical extensor muscle (CEM) fatigue on eye-hand tracking accuracy in healthy participants. Twenty-four healthy right-handed individuals were randomly assigned to either a control or CEM fatigue group. Each participant performed a tracking task which required shoulder rotation to move a circular object to a square target on a touchscreen computer. The task was performed with vision of the target and with the target hidden. A prone lying position, CEM fatigue protocol required participants to hold a 2 kg weight against gravity with their head in a neutral posture. The control intervention rested for 5 min, in a prone position, with the head supported in a neutral posture. Participants performed 3 trials with vision and 3 without at 5 different time points: (1) pre-intervention (fatigue or control), (2) immediately post-intervention, (3) 5 min, (4) 10 min, and (5) 20 min post-intervention. There were significant differences between the target with vision and the hidden condition for both groups between pre- and post-fatigue trials in angle of trajectory (p = 0.0001), and distance from release point to the target (p = 0.0001). Significant differences occurred in the hidden target condition for the fatigue group immediately post fatigue (p = 0.018) for distance from release to the target. Neck muscle fatigue reduced the accuracy of an upper limb tracking task to a hidden target, suggesting that altered afferent input from the neck due to fatigue may impair body schema and result in decreased upper limb performance accuracy.