Working Posture Evaluation of Clinical Student in Faculty of Dentistry University of Indonesia for the Scaling Task in Sitting Position in a Virtual Environment

Musculoskeletal disorders (MSDs) are global issues in the dental profession. This research evaluated the MSDs risk caused by the sitting working posture of clinical students performing the task of scaling. The evaluation using the virtual environment approach shows risk of MSDs in the students’ upper extremities such as neck, shoulder, and trunk. Further simulation based on the ideal sitting working posture shows that ergonomic scaling could be achieved when the patient sits at a 15° angle. When scaling the 1st and 4th quadrant of the teeth, the 9 o’clock position is used. Hence, the 11 o’clock position is used when scaling the 2nd and 3rd quadrant

Relationship between cervical spine and skeletal class II in subjects with and without temporomandibular disorders

AIM. To assess changes of cranio-cervical structure and of hyoid bone position in skeletal Class II subjects with and without Temporomandibular disorders (TMD). MATERIAL AND METHODS. The cephalometric analysis of 59 subjects with skeletal Class II were evaluated and compared. The measurements considerated were: ANB as parameter of Class II and C0-C1 distance, C1-C2 distance, cranio-cervical angle and hyoid bone position for the cervical spine analysis. Patients were divided into two subgroups: patients with TMD (group A) and patients without TMD (group B). TMD were evaluated with the Diagnostic Criteria for TMD (DC/TMD). Descriptive statistics and Pearson and Spearman correlation analysis, with p-value <0,005, were performed. RESULTS. C0-C1 and C1-C2 distance values and hyoid bone position resulted within normal range in the majority of patients examined. Cranio-cervical angle was alterated in 33 patients. The reduction of this angle with the increase of the ANB value resulted statistically significant in the group A, according to Pearson correlation index. No other data was statistically significant. CONCLUSIONS. Significant relationship between skeletal Class II and cervical spine cannot be highlighted. The alteration of cranio-cervical angle seems to be mildly present, with backward counterclockwise rotation of the head upon the neck in the sample (group A and B). The presence of TMDs as key factor in changes of neck posture could explain the different result between the two groups about relationship between ANB and cranio-cervical angle. This result should be further analyzed in order to better understand if cervical spine changes could be related to mandibular postural ones in the cranio-cervical space or to temporomandibular joints retropositioning, more recognizable in Class II with TMD, which could determine functional changes in other structures of this unit; neck posture also could be the result of a compensatory/ antalgic mechanism in response to TM

Importance of static adjustment of knee angle to determine saddle height in cycling

Knee flexion angle is used to determine saddle height during pedaling. However, it is unclear if knee flexion angle at upright standing posture affects measures and interpretation of knee flexion angle during cycling. The objective of this study was to assess the importance of adjusting knee angle during pedaling according to the knee angle at upright posture. Seventeen cyclists performed three 10 min cycling trials at different saddle heights to induce knee flexion angles (40º, 30º or 20º when crank was at the 6 o'clock position). Knee flexion angle was determined at the sagittal plane during cycling using a 2D motion analysis system. Alteration of saddle height was performed by subtracting the knee flexion angle determined during an upright standing posture from the observed knee flexion angle during cycling. Repeatability of knee angles at upright posture in the three trials was very good (ICC=0.73). A reduction in knee flexion angle of 10.6° (95%CI [8.6, 12.6º]) during cycling was found using the adjustment for upright standing posture (p3.0). As a result, saddle height is affected by adjustments based on knee angle measured in upright standing posture. Determining saddle height without adjusting knee angle for upright standing posture could lead to errors with possible effects on performance and/or injury risk

Influence of different stool types on muscle activity and lumbar posture among dentists during a simulated dental screening task

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

Effects of Simple Postural Instructions on Running Form Modification in Recreational Runners – Preliminary Findings

Background and purpose: Running is one of the most popular exercises but it is also an activity with a high incidence of injury. Running form modification involving a forward lean of the trunk and forefoot strike pattern has been shown to be effective in attenuating the impact forces of the lower extremity. However, it is currently unknown how these changes can be most effectively instructed and learned by the runners. Previous studies have shown that practicing a motor task with an external focus can facilitate learning and retention when compared to the more common internal focus instructions. The purpose of this study is to examine the effectiveness of external and internal attentional focus cues on trunk posture and peak vertical ground reaction force (GRF) during the stance phase of running. Subjects and Methods: Ten recreational runners were selected for this study and randomly assigned tone of two groups receiving external or internal instructions designed to modify their running form. Trunk posture and GRF were obtained using a 3D motion capture system and a force plate instrumented treadmill while running at 2.5 m/s and a self-selected speed. Subjects were tested over a 5-week time period consisting of 4 sessions over a 4-week training program, followed by a final session 1 week after the training program to analyze retention of running form modification. Results: Overall there was a significant increase in trunk angle observed over time, following instruction, for both groups at speed 2.5 m/s. Running at speeds 2.5 m/s and a self-selected speed showed no statistically significant difference in increased trunk angle or GRF when comparing an internal versus external attentional focus. Conclusion: Simple postural instructions were shown to be effective for inducing greater trunk lean during running. This study found no difference in trunk angle or GRF when comparing internal and external attentional focus groups. Future studies would benefit from using clear and proper instructions that incorporate internal and external attentional focus cues with feedback to reinforce motor learning

Comparison of lower body segment alignment of elite level hockey players to age-matched non-hockey players

Master's Project (M.A.) University of Alaska Fairbanks, 2015Lower body overuse and insidious onset injuries are thought to have an underlying biomechanical component which may be predisposing to injury. The purpose of this study was to compare lower body biomechanical characteristics for elite hockey players to matched controls. I hypothesize that elite hockey players have a greater degree of anterior pelvic tilt, greater varus knee angle, a higher foot arch and feet held in parallel more during gait than a matched non-skating population. Measures were taken of elite level, college aged, male hockey players and compared to cross country runners (ten subjects in each group) who served as controls for trunk angle, pelvic tilt angle, knee alignment, (varus/valgus angle), foot angle, arch index (arch height), hip, center of range of motion, hip external rotation, hip internal rotation, hip total range of motion (ROM), knee transverse plane ROM, and step width. The results obtained support the hypothesis for anterior pelvic tilt and foot angle during gait. Although knee angle was in the expected varus direction it was not significant and no differences were observed in the foot arch between the groups. All other measurements not directly related to the hypothesis were not significantly different with the exception of mean step width. The obtained results are important as recent literature describes a lower body posture of medial collapse into "dynamic valgus" as being predisposing to injury. Results show, on the spectrum from lower body varus to lower body valgus, hockey players are on the varus side of the spectrum in all attributes except arch height, which was similar in both populations. Since lower body alignment is thought to be coupled, this inconsistency appears contrary to the "medial collapse into dynamic valgus" model and may explain why foot orthotics and athletic shoes used as an injury intervention often fail

Two-dimensional posture evaluation in Parkinson’s disease: effect of loads on the spinal angle during gait

Parkinson’s Disease patients present diminished coordination caused by neural degeneration. This leads to large motor difficulties during gait such as balance loss and pronounced forward inclination of the upper body. This work assessed the spinal sagittal plane angle alterations in two groups: six parkinsonian patients and six control healthy subjects. This parameter was analyzed during gait under three conditions: without external loads and with external loads applied either on the chest or on the lower back area. Results were statistically compared by means of t-test of paired samples in both groups. For patients, a significant effect was found when loads were applied on the chest. On the other hand, healthy subjects showed no significant differences in either case.Fil: Celoria, Paula. Instituto Tecnológico de Buenos Aires; ArgentinaFil: Nanni, Federico. Instituto Tecnológico de Buenos Aires; ArgentinaFil: Pastore, Flavia. Instituto Tecnológico de Buenos Aires; ArgentinaFil: Pulenta, Sebastian. Instituto Tecnológico de Buenos Aires; ArgentinaFil: Tajerian, Matias. Instituto Tecnológico de Buenos Aires; ArgentinaFil: Pantazis, Lucio José. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Instituto Tecnológico de Buenos Aires; ArgentinaFil: Moscoso Vásquez, Hilda Marcela. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Instituto Tecnológico de Buenos Aires; ArgentinaFil: Cerquetti, Daniel. Fundación para la Lucha contra las Enfermedades Neurológicas de la Infancia; ArgentinaFil: Merello, Marcelo Jorge. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Fundación para la Lucha contra las Enfermedades Neurológicas de la Infancia; ArgentinaFil: Risk, Marcelo. Instituto Tecnológico de Buenos Aires; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Distributed Bio-inspired Humanoid Posture Control

This paper presents an innovative distributed bio-inspired posture control strategy for a humanoid, employing a balance control system DEC (Disturbance Estimation and Compensation). Its inherently modular structure could potentially lead to conflicts among modules, as already shown in literature. A distributed control strategy is presented here, whose underlying idea is to let only one module at a time perform balancing, whilst the other joints are controlled to be at a fixed position. Modules agree, in a distributed fashion, on which module to enable, by iterating a max-consensus protocol. Simulations performed with a triple inverted pendulum model show that this approach limits the conflicts among modules while achieving the desired posture and allows for saving energy while performing the task. This comes at the cost of a higher rise time.Comment: 2019 41st Annual International Conference of the IEEE Engineering in Medicine & Biology Society (EMBC

A Model of Movement Coordinates in Motor Cortex: Posture-Dependent Changes in the Gain and Direction of Single Cell Tuning Curves

Central to the problem of elucidating the cortical mechanisms that mediate movement behavior is an investigation of the coordinate systems by which movement variables are encoded in the firing rates of individual motor cortical neurons. In the last decade, neurophysiologists have probed how the preferred direction of an individual motor cortical cell (as determined by a center-out task) will change with posture because such changes are useful for inferring underlying cordinates. However, while the importance of shifts in preferred direction is well-known and widely accepted, posture-dependent changes in the depth of modulation of a cell's tuning curve, i.e. gain changes, have not been similarly identified as a means of coordinate inference. This paper develops a vector field framework which, by viewing the preferred direction and the gain of a cell's tuning curve as dual components of a unitary response vector, can compute how each aspect of cell response covaries with posture as a function of the coordinate system in which a given cell is hypothesized to encode its movement information. This integrated approach leads to a model of motor cortical cell activity that codifies the following four observations: 1) cell activity correlates with hand movement direction, 2) cell activity correlates with hand movement speed, 3) preferred directions vary with posture, and 4) the modulation depth of tuning curves varies with posture. Finally, the model suggests general methods for testing coordinate hypotheses at the single cell level and example protocols arc simulated for three possible coordinate systems: Cartesian spatial, shoulder-centered, and joint angle.Defense Advanced Research Projects Agency (N00014-92-J-4015); Defense Advanced Research Projects Agency and the Office of Naval Research (N00014-95-1-0409); National Science Foundation (IRI-90-00530, IRI-97-20333); Office of Naval Research (N00014-91-J-4100, N00014-92-J-1309, N00014-94-l-0940, N00014-95-1-0657)