Arm Rest Research Articles

Ergonomic soft mouse and armrest mouse pad

In this paper, it is shown that a teddy bear skin spongy mouse is a better option than a conventional plastic mouse design and that a portable arm rest mouse pad platform is far better than the conventional mouse platform placed to the side of the keyboard tray. Both designs help reducing arm abduction and related discomfort, pain, fatigue and soreness. Ten people voluntarily participated in the task and completed a series of psychophysical questions (Borg RPE [Rate of Perceived Exertion] Scale was used to evaluate). Results indicate a much smaller perception of pain and discomfort on palm and wrist with the spongy mouse rather than conventional designs, especially to palmar aponeurosis and ulna muscles. The mouse pad greatly reduced all the pressure points of hand and added comfort on wrist and forearm (e.g. flexor retinaculum (FR) and palmaris longus muscle area).

Park bench positionのための上肢固定器具の開発 : 安全性と簡便性の向上を目指して

Park bench positionのための上肢固定器具の開発 : 安全性と簡便性の向上を目指して

Perceived exertion responses to novel elbow flexor eccentric action in women and men.

The primary aim was to describe perceived exertion responses to different intensities of eccentric exercise in women and men. 42 adults (21 men and 21 women, 7 per condition) completed elbow extension exercises with a weight corresponding to 80%, 100%, or 120% of maximal voluntary concentric strength. Total work was equated by manipulating the number of repetitions in the 80% (N = 45), 100% (N = 36), and 120% (N = 30) conditions. A two-way ANOVA showed significant main effects for the intensity and sex factors. Perceived exertion ratings were strongly dependent on exercise intensity, and women reported lower RPEs than men. A separate three-way mixed model ANOVA that included a repetition factor showed that perceived exertion ratings increased similarly across the first 30 repetitions in all exercise conditions. Significant partial correlations were found between mean RPE during the eccentric exercise bout, and the mean intensity of delayed-onset muscle pain measured from 12- to 72-h postexercise after controlling for the relative exercise intensity (r12.3 = 0.28) or the maximum concentric strength of the elbow flexors (r12.3 = 0.33). 1) for both women and men, there is a positive association between the intensity of eccentric exercise performed with the elbow flexors and RPE; 2) perceived exertion ratings increase significantly then plateau when repeated eccentric muscle actions are performed at constant, submaximal absolute intensities; 3) women rate eccentric exercise performed at the same intensity (relativized to MVC-C) as being less effortful compared with men; and 4) RPE during eccentric exercise can account for a small but significant amount of variability in delayed-onset muscle pain after statistically controlling for differences in strength or relative intensity.

Method for expressing vibratory music and apparatus therefor

A method for expressing a vibratory music that may be felt as a piece of music for a human being in according with an acoustic vibration in an auditory region and/or a body sensible vibration or a body sensible acoustic vibration and an apparatus therefor are obtained. A signal about 16 Hz to 150 Hz (sound compass C 0 to D 3 ) in a frequency band of a body sensible vibration is used and what is composed and arranged in combination of strength, length, frequency, waveform and overlap of the vibration on a time basis, based upon a constant theory is expressed as a vibratory music. Transducers 5 are assembled into a backrest, a seat portion and a leg portion of a reclining seat, respectively. Speakers are mounted on a head portion. The transducers for outputting the sound vibrations are provided on both arm rests. It is possible to hear the sound output from the speakers and simultaneously feel the body sensible vibration by the body (back, hips, legs) by the two transducers and to obtain the sound vibration with the finger tips.

遺伝性圧脆弱性ニューロパチー（ＨＮＰＰ）の一例

Hereditary neuropathy with liability to pressure palsy (HNPP) is an autosomal dominant inherited disorder in which recurrent transitory palsy in the peripheral nerve occurs after a trivial pressure. We report on a case of atypical HNPP in which a long-standing non-restorative radial nerve palsy occurred. (Case) Twenty one-year-old female. This patient slept with her right arm compressed between her body and the arm rest of her seat on the train for approximately 30 minutes in September 1999. When she woke up, she noticed that her right wrist and fingers could not extend. She consulted an orthopaedic surgeon and was diagnosed as having right radial nerve palsy. Because the symptoms had not recovered for three months, she was referred to our hospital. At the initial consultation, her muscle strength of extensers of the wrist and fingers was 2 by MMT (Manual muscle testing) grading. Her mother and sister had a past history of transient mononeural palsy. She was treated conservatively with cock-up splint and a low frequency electronic stimulation. One and half years after the onset of the symptoms, there was no sign of recovery of the palsy, so tendon transfers were performed. Biopsy of the sural nerve, performed simultaneously, showed tomacula of the nerve fibers.

The filmless radiology reading room: a survey of established picture archiving and communication system sites.

The purpose of this study was to survey radiologists experienced in soft-copy diagnosis using computer workstations about their current reading room environment, their impressions of the efficacy of their reading room design, and their recommendations based on their experience for improvement of the soft-copy reading environment. Surveys were obtained from radiologists at seven sites representing three major picture archiving and communication system (PACS) vendors throughout the world that have had extensive experience with soft-copy interpretation of radiology studies. The radiologists filled out a detailed survey, which was designed to assess their current reading room environment and to provide them with the opportunity to make suggestions about improvement of the PACS reading rooms. The survey data were entered into a database and results were correlated with multiple parameters, including experience with PACS, types of modalities interpreted on the system, and number of years of experience in radiology. The factors judged to be most important in promoting radiologist productivity were room lighting, monitor number, and monitor brightness. Almost all of the radiologists indicated that their lighting source was from overhead rather than indirect or portable light sources. Approximately half indicated they had the capability of dimming the brightness of the overhead lighting. Most radiologists indicated that they were able to adjust room temperature but that they did not have individual temperature controls at their workstations. The radiologists indicated that the most troublesome sources of noise included background noise, other radiologists, and clinicians much more than noise from computer monitors, technologists, or patients. Most radiologists did not have chairs that could recline or arm rests. Most did have wheels and the capability to swivel, both of which were judged important. The majority of chairs also had lumbar support, which was also seen to be important. Radiologists commonly adjusted room lighting and their reading chair, but rarely adjusted room temperature or monitor brightness. The median number of hours spent at the workstation before taken a "break" was 1.5. Common recommendations to improve the room layout included compartmentalization of the reading room and availability of the hospital/radiology information system at each workstation. The survey data suggest several areas of potential improvement based on radiologists' experience. Optimization of soft-copy reading room design is likely to result in decreased fatigue and increased productivity.

Deep Brain Stimulation of the Ventral Intermediate Nucleus of the Thalamus for Control of Tremors in Parkinson’s Disease and Essential Tremor

The beneficial effects of ventral intermediate nucleus (VIM) stimulation were evaluated in 20 patients with tremor refractory to medical therapy. Thalamic stimulation is a non-ablative procedure which has the advantage of a reversible, non-destructive lesion. Eleven patients [7 with Parkinson’s disease (PD) and 4 with essential tremor (ET)] received unilateral VIM implantation, while 9 patients had staged bilateral VIM implantation (4 with PD, 5 with ET). PD patients showed a significant improvement in contralateral arm and leg rest tremor and ipsilateral leg rest tremor (p < 0.02) at a mean follow-up period of 16.2 ± 7.0 months. Patients with PD did not demonstrate any significant decrease in medication use at follow-up. ET patients demonstrated significant improvement in postural and action tremor in the contralateral arm (p < 0.001), but no significant improvement in the contralateral leg tremor at follow-up. Significant improvements were also seen in ET patients in the Clinical Rating Scale for Tremor (p < 0.001) with respect to several activities of daily living at a mean follow-up of 14.9 ± 8.1 months. Deep brain stimulation is a safe and effective treatment for severe tremor refractory to medications. It is a highly effective, reversible, adaptable, and predictable procedure which avoids the complication of cognitive deficit seen in patients with bilateral thalamotomies.

Absorbed Power and Mechanical Impedance of the Seated Human Measured within a Real Vehicle Environment Compared with Single Axis Laboratory Data

It is known that exposure to whole-body vibration when driving different types of vehicles may cause health effects and discomfort. Absorbed power might be a good quantity for assessing the risk of injury due to such exposure. Mechanical impedance is a measure which describes biodynamics and can define human response to vibration. It can then also be used in the design of preventative measures. The mechanical impedance of the human body in the vertical direction is presented in the ISO-standard 5982 (1981). However, it does not show concordance with results from later studies. This study has investigated how to measure and quantify absorbed power and mechanical impedance in a real vehicle environment. The vehicle was an 8-seater minibus driven on a snow covered gravel road at a speed of approximately 50 kmh−1. Three male subjects were exposed to vibration in the vehicle, sitting on a rigid seat mounted at the back of the minibus. Two postures were used, sitting erect and relaxed. Force and acceleration were measured using a specially designed seat plate. The results showed that absorbed power and mechanical impedance can be measured in a vehicle, but the results differ from other published single-axis exposure results. There seems to be a force cross-talk between the directions. This force distorts the results if the difference in vibration magnitude is as large as in this study. For instance, absorbed power negative results are shown around the frequency range 5–10 Hz in the x direction. Further research is needed in order to define the level and linearity of the force cross-talk. In addition, studies to investigate other conditions, such as back and arm rests, seat foam and suspension seats he of great interest.

Subjective assessment of fork-lift truck seats under laboratory conditions

A subjective assessment of fork-lift truck seats has been carried out to assess the range of preferred seat dimensions and the acceptability of different seat adjustments to fork-lift truck drivers. Twelve fork-lift truck seats fitted to a fixed bench were assessed by twelve fork-lift truck drivers. For each seat, each driver completed a questionnaire that covered the following areas: eleven seat dimensions, four seat adjustments and other features (arm rests, safety belts and safety wings). The drivers assessed the dimensions of a seat chosen at random, before moving to the adjacent seat in either a clockwise or anticlockwise direction. Before each assessment, they were asked to look forward and backward in the seat as though they were driving a fork-lift truck. In general, significant correlations were obtained between the subjective assessments and objective measurements of the seat dimensions. This enabled preferred seat dimension ranges to be defined. Fork-lift truck drivers ranked the forward–backward and the backrest inclination adjustments as most important. The results showed that although the drivers had previous experience in the use of suspension seats, they did not understand the purpose of the weight adjustment. All adjustments should be easy to find, accessible, easy to move and they should enable a range of adjustments. In addition, clear and simple information on the seat is needed, especially for the weight adjustment. The most recently designed seats generally had dimensions within the preferred ranges compared with the older generation seats, mainly because they had more adjustments. However, the results show that adjustments on fork-lift truck seats could be improved further. Some tentative conclusions are made for the preferred fork-lift truck seat dimensions and adjustment ranges which are based on the evidence from this restricted sample of fork-lift truck drivers. They may be useful for seat and truck designers in the preparation of a standard on fork-lift truck seat dimensions.

TRANSIENT VASODILATION UPON ARM ELEVATION ABOVE HEART IS MEDIATED BY WITHDRAWAL OF VENO- ARTERIOLAR REFLEX VASOCONSTRICTION

1071 We tested the hypothesis that reductions in venous pressure and volume upon arm elevation might augment resting forearm blood flow (FBF) via withdrawal of veno-arteriolar reflex mediated vasoconstriction. 9 subjects were seated with the right forearm supported in an arm rest below heart level. To temporarily empty the forearm veins, the subject was lowered for 4 s (acute) or 2 min (prolonged) and then raised again with the arm support rotating about a fixed axis. 2 conditions were performed during both acute and prolonged forearm elevation. Control: passive forearm elevation to empty forearm veins. Venous cuff: upper arm venous cuff inflation (30 mmHg) to prevent venous emptying. Mean arterial pressure at heart level and heart rate did not change with arm position or time. Reductions in forearm volume and venous pressure with arm elevation were prevented with venous cuff inflation. Lowering the forearm after 4 s increased FBF (Doppler ultrasound) by 343% above baseline in control vs. 86% in the venous cuff condition. With prolonged forearm elevation a transient increase in FBF to 87% above baseline started within 6 s in the control but not the venous cuff condition. FBF increased by 149% vs. baseline upon forearm lowering after 2 min of forearm elevation in control vs. 118% in the venous cuff condition. These results suggest that venous emptying upon forearm elevation evokes vasodilation that might be due to a withdrawal of veno-arteriolar reflex mediated vasoconstriction. Both this transient vasodilation and the increased arterial to venous pressure gradient can contribute to the transient increase in FBF on lowering.

The Smith Shield: a head box for patient protection and repositioning of the surgeon's camera assistant during laparoscopic surgery

Objective To reduce the difficulty and fatigue associated with long and complex laparoscopic procedures; to protect the face and airway of the patient from pressure from the surgeon's arms, and to allow easy operating from directly over the head end of the operating table, whilst maintaining access for the anaesthetist and monitoring equipment. Design We designed and patented the Smith Shield, a perspex ‘box’ with three rectangular sides that attaches over the anaesthetized patient's head. It functions as a Mayo table and surgeon's arm rest and holds equipment quivers for keeping laparoscopic instruments ready for use. Subjects and settings We have used the Smith Shield for all the minimal access procedures performed in our unit between January 1997 and June 1998. Other teams have also used the shield in place of the Mayo table for open procedures, most notably colposuspension. Results Most of the surgeons in our directorate now choose to use the shield for all but the most simple of laparoscopic procedures, as they have been so impressed with its advantages. All of our regular anaesthetists, after gaining familiarity with the correct positioning of the patient's arms and intravenous lines, comment that access to the patient for monitoring is satisfactory, and they commend the protection offered to the patient by the shield. Conclusion We now regard the Smith Shield as an essential part of our standard laparoscopic equipment as the ability to operate comfortably from the head end of the table has greatly reduced the difficulty of complex procedures.

Facilitating the sit-to-stand transfer: a review

The ability to transfer weight from a seated position to one of standing is a common activity of daily living. However, many older and/or disabled people have difficulty rising from a chair. As rising is a precursor to gait, finding ways by which the process of rising from a chair can be facilitated, such as providing arm rests, raising seat height, and/or using mechanical ejector devices, is very important. This review examines the efficacy of each of these aids in terms of facilitating sit-to-stand transfers performed by older and/or disabled individuals. It was concluded that regardless of seat height or use of a mechanical ejector device, all chairs prescribed for older and/or disabled individuals should have arm rests which can be used to assist body propulsion and balance when rising, and all users must be trained in correct use of a chair's features.

Rising from chair after total knee arthroplasty

Objective. This study was performed to determine the biomechanics of chair rising by patients after successful total knee arthroplasty (TKA). Design. Relative full body joint positions and ground reaction forces were measured by a motion analysis system and two force plates. Background. Chair-rise produces increased joint forces and moments compared with level walking, and it is difficult to rise from a chair for most patients with neurological or musculoskeletal abnormalities. Previous motion studies of patients after TKA had focused on gait analysis and stair climbing. Methods. Twelve patients after successful TKA were studied while performing sit-to-stand transfer from a chair at four chair heights without the use of arm rests. The results of this group were compared with those of 12 healthy elderly subjects and 14 osteoarthritic patients before TKA. Results. Compared with the healthy elderly group during chair rising, the patients after TKA had increased horizontal mass center velocity, increased vertical hip joint forces, the maximum sound-side hip extension moment, but decreased vertical mass center velocity. Conclusion. Compensatory mechanisms of chair rising were adopted by the arthritic patients before and after TKA. The mechanisms include increased forward body bending and more weight shift on the sound side.

A kinematic and kinetic analysis of the sit-to-stand transfer using an ejector chair: implications for elderly rheumatoid arthritic patients

Twelve elderly female rheumatoid arthritis patients (mean age=65.5±8.6 yr) were assessed rising from an instrumented Eser Ejector chair under four conditions: high seat (540 mm), low seat (450 mm), with and without the ejector mechanism operating. Sagittal plane motion, ground reaction forces, and vertical chair arm rest forces were recorded during each trial with the signals synchronised at initial subject head movement. When rising from a high seat, subjects displayed significantly ( p<0.05) greater time to seat off; greater trunk, knee and ankle angles at seat off; increased ankle angular displacement; decreased knee angular displacement; and decreased total net and normalised arm rest forces compared to rising from a low seat. When rising using the ejector mechanism, time to seat off and trunk and knee angle at seat off significantly increased, whereas trunk and knee angular displacement, and total net and normalised arm rest forces significantly decreased compared to rising unassisted. Regardless of seat height or ejector mechanism use, there were no significant differences in the peak, or time to peak horizontal velocity of the subjects’ total body centre of mass, or net knee and ankle moments. It was concluded that increased seat height and use of the ejector mechanism facilitated sit-to-stand transfers performed by elderly female rheumatoid arthritic patients. However, using the ejector chair may be preferred by these patients compared to merely raising seat height because it does not necessitate the use of a footstool, a possible obstacle contributing to falls.

Shoulder-arm muscle load and performance during control operation in forestry machines: Effects of changing to a new arm rest, lever and boom control system

Three work station design studies in forestry machines were carried out with regard to shoulder/ arm muscle load. (1) In an arm rest study, a movable (in the sagittal plane) arm rest was compared with a fixed one; (2) in a lever study, a mini lever with a small deflection was compared with an ordinary hand lever; (3) in a boom control study, a computer controlled boom system was compared with an ordinary boom system. In the arm rest study eight male subjects carried out lever operations in the laboratory. In the lever and boom studies, 15 male forestry students operated forwarders. Muscle load, cycle time, skill, perceived exertion, heart rate and preferred set up were recorded. The muscle loads on the upper trapezius, infraspinatus, extensor carpi ulnaris and flexor carpi radialis were recorded by electromyography. With mini lever and movable arm rest the upper trapezius load was reduced with preserved or decreased cycle time, although the grand mean of the ‘static’ load level was only about 2% of maximal voluntary contraction (MVC) and the effects of the new designs were small (about 0.7% MVC). The subjects preferred the lever/arm rest also giving the lowest muscle load. No differences between levers or arm rests were found in skill, perceived exertion or heart rate. It was not possible to draw any definitive conclusions regarding effects of the boom control system, due to technical problems. According to the literature, the duration of lever operation has increased considerably in forestry during recent years as part of a rationalization process. Partly due to this, it is suggested that the investigated work station improvements may not be sufficient to eliminate the risk for shoulder-neck disorders.

A parametric study of a side airbag system to meet deflection based criteria.

A side airbag system comprising of 12 liter bag to cover the BioSid chest and the abdomen down to the arm rest level, and 75 mm of padding to cover the pelvic/thigh area was evaluated by a series of sled tests at two different velocities, 10 m/s and 12 m/s. The initial bag (over) pressure was varied from 0 to 80 kPa and the bag ventilation area was varied from zero to 1500 mm2. Compressed air was used to fill the bag. It was found that the ventilation of the bag reduced the maximum chest deflection by 30 percent and the maximum viscous criterion, VC, by 50 percent (comparison was made with the same bag without ventilation). A suitable initial bag (over) pressure was found to be about 50 kPa, when the loading of the abdomen was also taken into consideration. The results indicate that the chest deflection is proportioned to the door average velocity (during the first 20 ms of deflection) to the power of about 2 and that the VC is proportional to the same velocity to the power of about 4. It was also found that a 12 liter ventilated side airbag resulted in 30-40 percent lower chest deflection and about 60 percent lower VC than 50 mm of chest padding (Ethafoam 220).

Chair Design Affects How Older Adults Rise from a Chair

To determine how modifications of key chair design aspects, such as seat height, posterior seat tilt, backrest recline, seat compressibility, and armrest placement, affect how older adults rise from a chair and the seating comfort they experience. Cross-sectional comparison. Congregate housing facility and university laboratory. Two groups of volunteers, Old (n = 29, mean age 84) and Young (n = 21, mean age 23). Analysis of time to rise, body motion (determined by use of digitized videotaping), and self-reported difficulty when subjects rose from a variety of controlled chair settings thought to represent important chair design specifications encountered by older adults. Subjects also reported their comfort while being seated in these settings. Lowered seat height, increased posterior seat tilt and backrest recline, and perhaps increased seat compressiblity cause increased time to rise, increased body motion, and increased self-reported ratings of rise difficulty in both Young and Old groups. Under the most challenging conditions, the effect appears to be stronger in the Old than in the Young: a few Old were unable to rise, and the Old took disproportionately longer to rise and used disproportionately greater neck motion (P generally < 0.001) compared with the Young. Arm rest placement did not alter rise performance or ratings significantly. The conditions in which rise difficulty increases or decreases do not correspond exactly to conditions in which comfort increases or decreases. Some aspects that increase rise difficulty, such as tilt/recline and seat compressiblity, may also increase comfort. Aspects of chair design such as lowered seat height, increased posterior seat tilt, increased back recline, and increased compressibility interfere with chair egress in older adults. While decreasing ease of egress, however, these same factors may increase seating comfort. Furniture designers and manufacturers must find a balance between degree of sitting comfort, ease of egress and the degree to which the seating device facilitates functional independence, particularly to meet the needs of disable older adults.

Upper Limb Disorders – Time to relax?

Summary Experiments with a small number of people showed that keyboard operators tended to find working with an arm rest more comfortable than having no support, though the results were not conclusive and further research is required. Experiments with a small number of people showed that keyboard operators tended to find working with an arm rest more comfortable than having no support, though the results were not conclusive and further research is required.

46. 心血管撮影用腕置き台の開発

46. 心血管撮影用腕置き台の開発

Electrophysiologic detection of extrapyramidal motor signs in Alzheimer's disease

We applied quantitative methods to measure extrapyramidal signs in 50 Alzheimer's disease (AD) patients and 40 age-matched control subjects. We measured tremor using accelerometers, bradykinesia using computer-detected reaction times (RTs) and movement times (MTs), and rigidity using a strain gauge linked to a movable arm rest. We excluded subjects with a clinical diagnosis of Parkinson's disease and subjects who required antiparkinsonian, neuroleptic, or anxiolytic medications. Aside from rigidity in two patients, there were no extrapyramidal signs on clinical examination. Based on electrophysiologic measures, however, there was a significant increase in muscle tone (p < 0.001), RT (p < 0.01), and MT (p < 0.03) in AD patients as a group compared with control subjects. Within the AD group, muscle tone and MTs increased across clinical stages of dementia severity (p < 0.05). Tremor frequency and amplitude were normal in AD subjects. These data indicate that quantitative neurophysiologic measures are superior to conventional clinical examinations in detecting extrapyramidal signs in AD. The pathologic substrates of extrapyramidal signs in AD are uncertain but seem to be linked to the degenerative AD process.