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Effect of Four Computer Keyboards in Computer Users with Upper Extremity Musculoskeletal Disorders
Abstract
Eighty computer users with musculoskeletal disorders participated in a 6-month, randomized, placebo-controlled trial evaluating the effects of four computer keyboards on clinical findings, pain severity, functional hand status, and comfort. The alternative geometry keyboards tested were: the Apple Adjustable Keyboard™ [kb1], Comfort Keyboard System™ [kb2], Microsoft Natural Keyboard™ [kb3], and placebo. Compared to placebo, kb3 and to a lesser extent kb1 groups demonstrated an improving trend in pain severity and hand function following 6 months of keyboard use. However, there was no corresponding consistent improvement in clinical findings in the alternative geometry keyboard groups compared to the placebo group. Overall, there was a significant correlation between improvement of pain severity and greater satisfaction with the keyboards. These results provide evidence that keyboard users may experience a reduction in hand pain after several months of use of some alternative geometry keyboards. Am. J. Ind. Med. 35:647–661, 1999. Published 1999 Wiley-Liss, Inc.
... This growing increase in computer/keyboard usage could lead to an increase in the risk of various workrelated musculoskeletal disorders (WMSDs), which are already prevalent among office workers (Hales et al. 1994;Norman et al. 2004;Rempel et al. 2008;Toosi et al. 2015). Given the high prevalence of WMSDs among computer users (between 40% to 80%) and the growing global computer workforce, concerns exist about the escalation of computer related injury (Tittiranonda et al. 1999;Katz et al. 2000). Carpal tunnel syndrome (CTS) is one of the most reported WMSDs among office workers (Werner and Andary 2002). ...
Given the growing global computer workforce, concerns exist about the escalation of computer related injury with Carpal tunnel syndrome (CTS) being one of the most reported work-related musculoskeletal disorders (WMSDs) among office workers. The optimal range of keyboard angles for sitting and standing positions based on wrist posture, forearm muscle activities and user preference as well as the keyboard location in relation to user position were analysed. 30 volunteers with an above 40 words per minute typing speed participated in this study. Result show that, although user prefer to use positive keyboard angle, the negatively tilted keyboard is more ergonomically friendly at both sitting and standing workstations, reducing muscle activity and awkward wrist posture while maintaining performance. The findings indicate that negative sloped keyboard might have the possibility to reduce the risk of developing CTS in office workers.Practitioner summary: This study determines the range of optimal slope of keyboard angle in a sit and stand workstation. Our results indicate a trend in the negative slope keyboard as an ergonomically friendly option for the intervention to Carpal tunnel pressure.
The curved design is ubiquitous, with a vast user base due to its similarity with in shape to human physiological structure. The curved QWERTY keyboard layout was proposed for one-handed usage on smartphones with ambiguous effects. This study evaluated whether the curved QWERTY could optimize the user experience and input performance on large smartphones better than the traditional straight QWERTY layout. Eight measurements were used to evaluate the usability of each design, six suggesting curved QWERTY failed to achieve outstanding typing performance or subjective user experience, while the other two indicators showed that curved QWERTY had advantages in touch dispersion and touching offset, indicating the possible higher usability it could reach. The results also investigated the potential application of curved designs and provided insights into the optimization methods.
Objective: Musculoskeletal system problems emerged in students who had to attend classes with a computer or smartphone during the weekly course hours, due to the fact that the universities providing face-to-face education switched to the online method of distance education due to the Covid-19 pandemic. Purpose of the study; To determine the severity of the pain experienced by the students, to reveal its relationship with disability, and to find the factors that induce pain and disability in daily life. Method: 100 students between the ages of 18-25, who attended distance education for at least 2 academic semesters and met the study criteria were included in the study. After the Sociodemographic Data Questionnaire was applied to the students included in the study, the Arm, Shoulder and Hand Problems Quick Questionnaire (Q-DASH), Neck Disability Index and NRS tests were applied. Results: As a result of the Quick Questionnaire for Arm, Shoulder and Hand Problems (Q-DASH), 43% of the students included in the study had moderate disability, and according to the Neck Disability Index, 37% of the study group had complete disability. According to multivariate regression analysis, gender (p
: One of the most common forms of entrapment neuropathy is Carpal Tunnel Syndrome (CTS). There are various treatment options for CTS. However, there are no clear and structured guidelines. This review classified the existing treatments and developed an algorithm to help physicians to choose the best option for their patients. Treatment options were summarized in three sections: non-surgical management of CTS, post-operative management of CTS, and practical open carpal tunnel release post-op protocol. The physicians can prescribe multiple treatment options to CTS patients. Corticosteroid in oral or injectable form has strong evidence in pain control and functional improvement in the short term. Shockwave therapy and nocturnal wrist splints display moderate therapeutic effects. Post carpal tunnel release rehabilitation can be started a few days after the operation.
The Academy of Orthopaedic Physical Therapy and the Academy of Hand and Upper Extremity Physical Therapy have an ongoing effort to create evidence-based clinical practice guidelines (CPGs) for orthopaedic and sports physical therapy management and prevention of musculoskeletal impairments described in the World Health Organization's International Classification of Functioning, Disability and Health (ICF). This particular guideline focuses on hand pain and sensory deficits in carpal tunnel syndrome. J Orthop Sports Phys Ther 2019;49(5):CPG1-CPG85. doi:10.2519/jospt.2019.0301.
Introduction: Nowadays, computers, personal telephones (smartphones) and other electronic devices are widely used in many areas of everyday life, making them indispensable tools in the workplace, as well as other environments, e.g. at home. Studies from recent years have shown that the mere use of a computer keyboard for many hours carries the risk of pain in the hand, forearm, arm, shoulder girdle, neck and other parts of the motor organs.
Aim: The aim of the literature review carried out in this work was to determine what potential threats are posed by standard keyboards and smartphone touch keypads, as well as the comparison of standard and ergonomic keyboards.
Material and methods: The following databases were searched: PubMed, ResearchGate and Cochrane Library, in which 13 articles meeting the inclusion and exclusion criteria were found (6 regarding standard keyboards, 3 concerning ergonomic keyboards and 4 related to smartphone keypads).
Results: The results of these studies indicate exposure to dysfunctions of the musculoskeletal system associated with typing on keyboards, especially when writing fast, with high pressure, in unnatural positions of the wrists and forearms and during long-term writing. Ergonomic keyboards can be a good alternative to standard keyboards, especially for those who use one for more than four hours a day. This literature review indicates the need for more research, especially randomized clinical trials among a large population.
Conclusions: 1. The use of keyboards of selected electronic devices with different ergonomic characteristics has an adverse effect on the functionality of the shoulder girdle and upper limb, mainly generating painful symptoms with different clinical characteristics. 2. The most important influence on the occurrence of functional disorders and pain complaints concerning the shoulder girdle and upper limb when using a keyboard with different ergonomic characteristics regards the strength of pressure on the keys, speed of typing as well as long-lasting and forced positioning of the wrists and forearms.
Keyboards, ergonomics, pain
Background:
Work-related upper limb and neck musculoskeletal disorders (MSDs) are one of the most common occupational disorders worldwide. Studies have shown that the percentage of office workers that suffer from MSDs ranges from 20 to 60 per cent. The direct and indirect costs of work-related upper limb MSDs have been reported to be high in Europe, Australia, and the United States. Although ergonomic interventions are likely to reduce the risk of office workers developing work-related upper limb and neck MSDs, the evidence is unclear. This is an update of a Cochrane Review which was last published in 2012.
Objectives:
To assess the effects of physical, cognitive and organisational ergonomic interventions, or combinations of those interventions for the prevention of work-related upper limb and neck MSDs among office workers.
Search methods:
We searched the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, CINAHL, Web of Science (Science Citation Index), SPORTDiscus, Embase, the US Centers for Disease Control and Prevention, the National Institute for Occupational Safety and Health database, and the World Health Organization's International Clinical Trials Registry Platform, to 10 October 2018.
Selection criteria:
We included randomised controlled trials (RCTs) of ergonomic interventions for preventing work-related upper limb or neck MSDs (or both) among office workers. We only included studies where the baseline prevalence of MSDs of the upper limb or neck, or both, was less than 25%.
Data collection and analysis:
Two review authors independently extracted data and assessed risk of bias. We included studies with relevant data that we judged to be sufficiently homogeneous regarding the interventions and outcomes in the meta-analysis. We assessed the overall quality of the evidence for each comparison using the GRADE approach.
Main results:
We included 15 RCTs (2165 workers). We judged one study to have a low risk of bias and the remaining 14 studies to have a high risk of bias due to small numbers of participants and the potential for selection bias.Physical ergonomic interventionsThere is inconsistent evidence for arm supports and alternative computer mouse designs. There is moderate-quality evidence that an arm support with an alternative computer mouse (two studies) reduced the incidence of neck or shoulder MSDs (risk ratio (RR) 0.52; 95% confidence interval (CI) 0.27 to 0.99), but not the incidence of right upper limb MSDs (RR 0.73; 95% CI 0.32 to 1.66); and low-quality evidence that this intervention reduced neck or shoulder discomfort (standardised mean difference (SMD) -0.41; 95% CI -0.69 to -0.12) and right upper limb discomfort (SMD -0.34; 95% CI -0.63 to -0.06).There is moderate-quality evidence that the incidence of neck or shoulder and right upper limb disorders were not considerably reduced when comparing an alternative computer mouse and a conventional mouse (two studies; neck or shoulder: RR 0.62; 95% CI 0.19 to 2.00; right upper limb: RR 0.91; 95% CI 0.48 to 1.72), and also when comparing an arm support with a conventional mouse and a conventional mouse alone (two studies) (neck or shoulder: RR 0.91; 95% CI 0.12 to 6.98; right upper limb: RR 1.07; 95% CI 0.58 to 1.96).Workstation adjustment (one study) and sit-stand desks (one study) did not have an effect on upper limb pain or discomfort, compared to no intervention.Organisational ergonomic interventionsThere is very low-quality evidence that supplementary breaks (two studies) reduce discomfort of the neck (MD -0.25; 95% CI -0.40 to -0.11), right shoulder or upper arm (MD -0.33; 95% CI -0.46 to -0.19), and right forearm or wrist or hand (MD -0.18; 95% CI -0.29 to -0.08) among data entry workers.Training in ergonomic interventionsThere is low to very low-quality evidence in five studies that participatory and active training interventions may or may not prevent work-related MSDs of the upper limb or neck or both.Multifaceted ergonomic interventionsFor multifaceted interventions there is one study (very low-quality evidence) that showed no effect on any of the six upper limb pain outcomes measured in that study.
Authors' conclusions:
We found inconsistent evidence that the use of an arm support or an alternative mouse may or may not reduce the incidence of neck or shoulder MSDs. For other physical ergonomic interventions there is no evidence of an effect. For organisational interventions, in the form of supplementary breaks, there is very low-quality evidence of an effect on upper limb discomfort. For training and multifaceted interventions there is no evidence of an effect on upper limb pain or discomfort. Further high-quality studies are needed to determine the effectiveness of these interventions among office workers.
There is increasing evidence that alternative geometry keyboards may prevent or reduce arm pain or disorders and presumably the mechanism is by reducing awkward arm postures. However, the effects of alternative keyboards, especially the new designs, on wrist and arm postures are not well known. In this laboratory study, the wrist and forearm postures of 100 subjects were measured with a motion analysis system while they typed on 6 different keyboard configurations. There were significant differences in wrist extension, ulnar deviation, and forearm pronation between keyboards. When considering all 6 wrist and forearm postures together, the keyboard with an opening angle of 12°, a gable angle of 14°, and a slope of 0° appears to provide the most neutral posture among the keyboards tested in the configuration tested. This study identifies significant wrist and forearm posture differences between 6 keyboard configurations. These findings may assist in ergonomic recommendations regarding computer usage.
Time pressure from deadlines, awkward body postures and long-duration, continuous computer use are associated with musculoskeletal disorders (MSDs) in workers using computers. Few studies have examined computer-use-related MSDs in college students. This study investigated computer use patterns of college students, and made comparisons to a group of computer-using professionals. 234 students completed a web-based questionnaire on computer use habits and discomfort students associated with computer use. As a group, students reported their computer use to be at least ‘Somewhat likely’ 18 out of 24 h/day, compared to 12 h for the professionals. Students reported more uninterrupted work behaviours than the professionals. Younger graduate students reported 33.7 average weekly computing hours, similar to hours reported by younger professionals. Students generally reported more frequent upper extremity discomfort than the professionals. Frequent assumption of awkward postures was associated with frequent discomfort. Results signal a need for intervention prior to entry into the workforce.
Work-related upper extremity disorders (WRUEDs) are a major problem in modern society, and they represent the primary cause of absenteeism in North America and Western Europe (Health and Safety Executive (HSE), 2002; Punnett & Wegman, 2004). The impact of WRUEDs on workers themselves in terms of pain and disability is important, but these conditions, often chronic, also incur significant loss of quality of life and impact the workers’ families, co-workers, and employers (Huang, Feuerstein, & Sauter, 2002; Punnett & Wegman, 2004). The productivity loss and economic costs of WRUEDs for society are substantial, and the economic burden of WRUEDs is increasing, despite efforts in prevention and implementation of novel intervention strategies for sustainable return to work (RTW) (Fabrizio, 2002; Feuerstein et al., 1993; Katz et al., 2000). At the outset, it should also be noted that WRUED is an “umbrella term” used to describe a wide range of disorders of the muscles, tendons, bursae, nerves, or blood vessels, potentially caused or aggravated by work, that may affect the neck/shoulder region, the shoulder itself, the elbow, the wrist, or the hand (Burton, Kendall, Pearce, Birrell, & Bainbridge, 2009; Zakaria, Robertson, MacDermid, Hartford, & Koval, 2002). These disorders range from those that are relatively well defined and specific (disorders with a well-defined set of diagnostic criteria established from evidence-based approaches) to those that are considered nonspecific (ill-defined disorders for which signs and symptoms may be present without a clear pattern allowing for a specific diagnosis) (Van Eerd et al., 2003). Numerous other terms have also been used to describe WRUED, such as cumulative trauma disorders, repetitive physical overuse, or repetitive strain injuries, but this lack of consensus on the definition of WRUED has led to confusion (Burton et al., 2009; Katz et al., 2000).
The vague definitions of so-called repetitive stress injuries are indicative of the fact that scientific studies have failed to show that repetitive motion causes injury. Given the uncertainty about causation, work-related musculoskeletal disorders (WRMSDs) is a more readily accepted term to describe these phenomena. There is little doubt that most ergonomic interventions increase comfort in the work environment, which is of great benefit to the worker. Many proponents of ergonomics assert that the elimination of certain risk factors related to force, repetition, and posture can prevent or even cure work-related musculoskeletal disorders of the upper extremity. However, there is little scientific support for this position. Undue reliance on ergonomics to treat musculoskeletal disorders, to the exclusion of proper diagnosis and attention to medical and health risk factors, can have adverse consequences for the patient. Science rather than politics and public policy should determine what causes injury and disease. The failure of numerous plaintiffs in litigation regarding repetitive stress injury due to use of computer keyboards is important because, when judges and lay jurors were presented with both sides of the issue, they rejected these claims in a forum (the judicial system) that traditionally compensates individuals bringing so-called mass-tort cases.
Alternatively configured keyboards have been extensively marketed as one method to reduce musculoskeletal symptoms and musculoskeletal disorders in computer operators. This paper reviews current evidence about the effectiveness of alternative keyboards at reducing risky postures and improving musculoskeletal symptoms. In general, the literature strongly supports the ability of alternative keyboards to reduce potentially risky postures, but is much more equivocal about their ability to reduce musculoskeletal symptoms in the workplace.
Carpal tunnel syndrome (CTS)is due to entrapment of the median nerve and is the most common form of compressive neuropathy affecting 1%-3%of the general population [1, 2].Females in their fourth and fifth decades are four times more likely to suffer from CTS as opposed to men of the same age [3].Symptoms often include paresthesias into the thumb,index,long and half of the ring finger,as well as pain in the hand,wrist, and occasionally the forearm [4].These symptoms usu-ally worsen at night and with repetitive,strenuous activities utilizing the hands.In severe cases,atrophy of the thenar musculature can be present [5].The clinical diagnosis of CTS is generally straightforward;however, nerve conduction studies (NCS)and electromyogram (EMG)are often recommended to reliably confirm the diagnosis [6].
Purpose:
The increase in tablet usage allows people to perform computer work in non-traditional office environments. The aim of this study was to assess the effects of changes in tablet keyboard design on postures of the upper extremities and neck, discomfort, and usability under different usage positions during prolonged touch-typing.
Methods:
Eighteen healthy participants familiar with touch-screen devices were randomized into three usage positions (desk, lap, and bed) and completed six, 60-minute typing sessions using three virtual keyboard designs (standard, wide, split). Electrogoniometers continuously measured the postures of the wrists, elbow, and neck. Body discomfort and system usability were evaluated by questionnaires before and immediately after each typing session.
Results:
Separate linear mixed effects models on various postural measures and subjective ratings are conducted with usage position as the between-subject factors, keyboard design and typing duration as the with-in subject factors were conducted. Using the tablet in bed led to more extended wrists but a more natural elbow flexion than the desk position. The angled split virtual keyboard significantly reduced the extent of wrist ulnar deviation than the keyboard with either standard or wide design. However, little difference was observed across the usage position and keyboard design. When the postural data were compared between the middle and end of typing sessions, the wrists, elbow, and neck all exhibited a substantially increased range of joint movements (13% to 38%). The discomfort rating also increased significantly over time in every upper body region investigated. Additionally, the split keyboard design received a higher usability rating in the bed position, whereas participants had more satisfactory experience while using the wide keyboard in the traditional desk setting.
Conclusions:
Prolonged use of tablets in non-traditional office environments may result in awkward postures in the upper body that may expose users to greater risks of developing musculoskeletal symptoms. Adequate virtual keyboard designs show the potential to alleviate some postural effects and improve the user experience without changing the tablet form factors.
The burden of disabling musculoskeletal pain and injuries (musculoskeletal disorders, MSDs) arising from work-related causes in many workplaces remains substantial. There is little consensus on the most appropriate interventions for MSDs. Our objective was to update a systematic review of workplace-based interventions for preventing and managing upper extremity MSD (UEMSD). We followed a systematic review process developed by the Institute for Work & Health and an adapted best evidence synthesis. 6 electronic databases were searched (January 2008 until April 2013 inclusive) yielding 9909 non-duplicate references. 26 high-quality and medium-quality studies relevant to our research question were combined with 35 from the original review to synthesise the evidence on 30 different intervention categories. There was strong evidence for one intervention category, resistance training, leading to the recommendation: Implementing a workplace-based resistance training exercise programme can help prevent and manage UEMSD and symptoms. The synthesis also revealed moderate evidence for stretching programmes, mouse use feedback and forearm supports in preventing UEMSD or symptoms. There was also moderate evidence for no benefit for EMG biofeedback, job stress management training, and office workstation adjustment for UEMSD and symptoms. Messages are proposed for both these and other intervention categories.
Background:
Extended use of conventional computer input devices is associated with negative musculoskeletal outcomes. While many alternative designs have been proposed, it is unclear whether these devices reduce biomechanical loading and musculoskeletal outcomes.
Objective:
To review studies describing and evaluating the biomechanical loading and musculoskeletal outcomes associated with conventional and alternative input devices.
Methods:
Included studies evaluated biomechanical loading and/or musculoskeletal outcomes of users' distal or proximal upper extremity regions associated with the operation of alternative input devices (pointing devices, mice, other devices) that could be used in a desktop personal computing environment during typical office work.
Results:
Some alternative pointing device designs (e.g. rollerbar) were consistently associated with decreased biomechanical loading while other designs had inconsistent results across studies. Most alternative keyboards evaluated in the literature reduce biomechanical loading and musculoskeletal outcomes. Studies of other input devices (e.g. touchscreen and gestural controls) were rare, however, those reported to date indicate that these devices are currently unsuitable as replacements for traditional devices.
Conclusions:
Alternative input devices that reduce biomechanical loading may make better choices for preventing or alleviating musculoskeletal outcomes during computer use, however, it is unclear whether many existing designs are effective.
Background:
Modern computer users use the mouse almost three times as much as the keyboard. As exposure rates are high, improving upper extremity posture while using a computer mouse is desirable due to the fact that posture is one risk factor for injury. Previous studies have found posture benefits associated with using alternative mouse designs, but at the cost of performance and preference.
Objective:
To develop new computer mouse shapes, evaluate them versus benchmarks, and determine whether there are differences in wrist posture, pointing performance, and subjective measures.
Method:
Three concept mice were designed and evaluated relative to two existing benchmark models: a traditional flat mouse, and an alternative upright mouse. Using a repeated measures design, twelve subjects performed a standardized point-and-click task with each mouse. Pointing performance and wrist posture was measured, along with perceived fatigue ratings and subjective preferences pre and post use.
Results:
All of the concept mice were shown to reduce forearm pronation relative to the traditional flat mouse. There were no differences in pointing performance between the traditional flat mouse and the concept mice. In contrast, the fully vertical mouse reduced pronation but had the poorest pointing performance. Perceived fatigue and subjective preferences were consistently better for one concept mouse.
Conclusion:
Increasing mouse height and angling the mouse topcase can improve wrist posture without negatively affecting performance.
Fixed-split, ergonomic keyboards have been shown to reduce awkward wrist postures while maintain typing performance and improve the functional and medical status of those persons with hand pain as well as reduce the likelihood of developing signs and symptoms of musculoskeletal disorders such as carpal tunnel syndrome compared to typists using traditional, straight keyboards. Yet, the design can be improved. This paper describes the basic research, inspiration, and participatory design approach as well as the organizational obstacles in creating the new Microsoft® Natural® Ergonomic Keyboard 4000. The ergonomist had to overcome staid thinking in questioning the fundamental assumptions about the ergonomics of keyboard design and to overcome the product design paradigm of only fixing problems from stated and unstated user needs compared with realizing innovative designs that the average user cannot articulate or consider. An iterative design process resulted in a new ergonomic keyboard with a steeper gable angle, a curved key bed, a taller palm rest, and a palm rest lifter for a truly negative slope.
Objective: To determine if baseline discomfort severity would moderate differences in 5-month follow-up discomfort in those using a fixed split-angle (FSA) keyboard compared to those using a standard (ST) keyboard. Procedure: Computer operators with keyboard related musculoskeletal discomfort were randomly assigned to use an FSA keyboard or a ST keyboard in their workplace for 5 months. They reported weekly levels of discomfort using the Weekly Discomfort Survey. Result: The interaction between baseline severity and keyboard was significant. This significant interaction suggests that those who had moderate/severe baseline discomfort who used the FSA keyboard improved significantly more than: 1) those who had moderate/severe baseline discomfort who used the ST keyboard; or 2) those who had none/mild baseline discomfort and used either keyboard.
An increased usage of tablets and the introduction of ultrabooks has brought consumer demands for smaller, lighter, more mobile devices to the forefront. With computing technologies gravitating towards thinner designs, there is increased pressure to reduce key displacement (key travel) in order to accommodate the reduced thickness. It is important to understand how these reductions in key travel may affect the users’ performance and
preferences. In this study, we examined the physical key characteristics to determine if they affect user performance or preference on various notebook computer keyboards. We compared four keyboards varying in key travel distances from 0.0mm to 2.0mm. Participants completed a 7-minute typing task on each of the four keyboards.Performance data (words typed per minute and error types) and (speed and accuracy) were collected for each of the
keyboards at the end of each condition. The results showed that words per minute were higher with the 2.0 mm and 1.6 mm keyboards and lower with the 0.4 mm and virtual keyboards. The virtual keyboard had a lower accuracy than the other three keyboards. Performance and usability ratings were significantly lower for the virtual keyboard
compared with the other keyboards. Overall, subjective and objective measures of performance and usability indicated that 1.6 mm keyboard was preferred.
Frequently wiggle of wrists is the primary cause of muscle fatigue and occupational diseases in the computer keyboard operation. It is revealed that the wiggle of wrist is caused by the workspace limit of finger tip. Based on the movement study and workspace analysis for human finger, a new type of computer keyboard designed with ergonomic consideration is put out. A tilting keyboard is used in the new configuration to fit the shape of finger workspace. It was approved by experiment that the new keyboard could reduce the rotation of wrist obviously, therefore to improve the comfort and avoid disorder of the wrist during operation.
The neck and shoulder pain (NSP) symptoms are very common among intensive computer users. This paper reviews recent 20 years’ research publications, which have focused on pathophysiology and other aspects of the neck and shoulder pain related to computer use (NSPRCU). The disorder is usually multidimensional, occupational, personal and social factors are among these evolved. Suggestions concerning the diagnostics, procedures of prevention, and treatment options have been discussed. As the details of pathophysiology of these disorders are not yet clear, further studies on NSPRCU are necessary.
Obesity in the workplace is associated with loss of productivity, high medical care expenses, and increased rates of work-related injuries and illness. Thus, effective, low-cost interventions are needed to accommodate the size of today's obese office worker while alleviating potential physical harm associated with musculoskeletal disorders. Utilizing a sample of 22 overweight and obese office workers, this pilot study assessed the impact of introducing an alternative, more ergonomically-sound keyboard on perceptions about design, acceptability, and usability; self-reported body discomfort; and typing productivity. Data were collected using self-reported questionnaires and objective typing tests administered before and after the intervention. The intervention duration was six weeks. After switching from their standard work keyboard to an alternative keyboard, all participants reported significant decreases in lower back discomfort (t = 2.14, P = 0.044); although obese participants reported significant decreases in both upper (t = 2.46, P = 0.032) and lower (t = 2.39, P = 0.036) back discomfort. No significant changes were observed in overall typing performance scores from baseline to follow-up. Findings suggest that such interventions may be introduced into the workforce with positive gains for workers without reducing short-term worker productivity.
Objectives: Work-related musculoskeletal disorders of computer users represent a growing problem for the workplace, the health care system, and the society. Office ergonomic educational strategies have been developed and implemented to address this concern. In this study, we aimed to establish and test an e-learning method for office ergonomics training and evaluate immediate and short-term effects of the training. Methods: Web-based ergonomics training was designed and delivered. Assessments included demographic, knowledge, and behavioral aspects. Several online surveys and the Rapid Upper Limb Assessment [RULA] were used as assessment tools. Results: The Knowledge Assessment Score after the training significantly improved from 4.70 to 9.58. Behavioral assessment scores including the RULA and Workplace Interaction Score improved from 5.72 to 5.11 and 6.39 to 7.99, respectively. Conclusion: It was observed that employees had converted the knowledge they gained by training into behavioral change, and they reflected this in their working postures and workplace interaction.
Work-related upper limb disorder (WRULD), repetitive strain injury (RSI), occupational overuse syndrome (OOS) and work-related complaints of the arm, neck or shoulder (CANS) are the most frequently used umbrella terms for disorders that develop as a result of repetitive movements, awkward postures and impact of external forces such as those associated with operating vibrating tools. Work-related CANS, which is the term we use in this review, severely hampers the working population.
To assess the effects of conservative interventions for work-related complaints of the arm, neck or shoulder (CANS) in adults on pain, function and work-related outcomes.
We searched the Cochrane Central Register of Controlled Trials (The Cochrane Library, 31 May 2013), MEDLINE (1950 to 31 May 2013), EMBASE (1988 to 31 May 2013), CINAHL (1982 to 31 May 2013), AMED (1985 to 31 May 2013), PsycINFO (1806 to 31 May 2013), the Physiotherapy Evidence Database (PEDro; inception to 31 May 2013) and the Occupational Therapy Systematic Evaluation of Evidence Database (OTseeker; inception to 31 May 2013). We did not apply any language restrictions.
We included randomised controlled trials (RCTs) and quasi-randomised controlled trials evaluating conservative interventions for work-related complaints of the arm, neck or shoulder in adults. We excluded trials undertaken to test injections and surgery. We included studies that evaluated effects on pain, functional status or work ability.
Two review authors independently selected trials for inclusion, extracted data and assessed risk of bias of the included studies. When studies were sufficiently similar, we performed statistical pooling of reported results.
We included 44 studies (62 publications) with 6,580 participants that evaluated 25 different interventions. We categorised these interventions according to their working mechanisms into exercises, ergonomics, behavioural and other interventions.Overall, we judged 35 studies as having a high risk of bias mainly because of an unknown randomisation procedure, lack of a concealed allocation procedure, unblinded trial participants or lack of an intention-to-treat analysis.We found very low-quality evidence showing that exercises did not improve pain in comparison with no treatment (five studies, standardised mean difference (SMD) -0.52, 95% confidence interval (CI) -1.08 to 0.03), or minor intervention controls (three studies, SMD -0.25, 95% CI -0.87 to 0.37) or when provided as additional treatment (two studies, inconsistent results) at short-term follow-up or at long-term follow-up. Results were similar for recovery, disability and sick leave. Specific exercises led to increased pain at short-term follow-up when compared with general exercises (four studies, SMD 0.45, 95% CI 0.14 to 0.75)We found very low-quality evidence indicating that ergonomic interventions did not lead to a decrease in pain when compared with no intervention at short-term follow-up (three studies, SMD -0.07, 95% CI -0.36 to 0.22) but did decrease pain at long-term follow-up (four studies, SMD -0.76, 95% CI -1.35 to -0.16). There was no effect on disability but sick leave decreased in two studies (risk ratio (RR) 0.48, 95% CI 0.32 to 0.76). None of the ergonomic interventions was more beneficial for any outcome measures when compared with another treatment or with no treatment or with placebo.Behavioural interventions had inconsistent effects on pain and disability, with some subgroups showing benefit and others showing no significant improvement when compared with no treatment, minor intervention controls or other behavioural interventions.In the eight studies that evaluated various other interventions, there was no evidence of a clear beneficial effect of any of the interventions provided.
We found very low-quality evidence indicating that pain, recovery, disability and sick leave are similar after exercises when compared with no treatment, with minor intervention controls or with exercises provided as additional treatment to people with work-related complaints of the arm, neck or shoulder. Low-quality evidence also showed that ergonomic interventions did not decrease pain at short-term follow-up but did decrease pain at long-term follow-up. There was no evidence of an effect on other outcomes. For behavioural and other interventions, there was no evidence of a consistent effect on any of the outcomes.Studies are needed that include more participants, that are clear about the diagnosis of work-relatedness and that report findings according to current guidelines.
We conducted this study to investigate how physical and cognitive ergonomic workloads would differ between robotic and laparoscopic surgeries and whether any ergonomic differences would be related to surgeons' robotic surgery skill level. Our hypothesis is that the unique features in robotic surgery will demonstrate skill-related results both in substantially less physical and cognitive workload and uncompromised task performance.
Thirteen MIS surgeons were recruited for this institutional review board-approved study and divided into three groups based on their robotic surgery experiences: laparoscopy experts with no robotic experience, novices with no or little robotic experience, and robotic experts. Each participant performed six surgical training tasks using traditional laparoscopy and robotic surgery. Physical workload was assessed by using surface electromyography from eight muscles (biceps, triceps, deltoid, trapezius, flexor carpi ulnaris, extensor digitorum, thenar compartment, and erector spinae). Mental workload assessment was conducted using the NASA-TLX.
The cumulative muscular workload (CMW) from the biceps and the flexor carpi ulnaris with robotic surgery was significantly lower than with laparoscopy (p < 0.05). Interestingly, the CMW from the trapezius was significantly higher with robotic surgery than with laparoscopy (p < 0.05), but this difference was only observed in laparoscopic experts (LEs) and robotic surgery novices. NASA-TLX analysis showed that both robotic surgery novices and experts expressed lower global workloads with robotic surgery than with laparoscopy, whereas LEs showed higher global workload with robotic surgery (p > 0.05). Robotic surgery experts and novices had significantly higher performance scores with robotic surgery than with laparoscopy (p < 0.05).
This study demonstrated that the physical and cognitive ergonomics with robotic surgery were significantly less challenging. Additionally, several ergonomic components were skill-related. Robotic experts could benefit the most from the ergonomic advantages in robotic surgery. These results emphasize the need for well-structured training and well-defined ergonomics guidelines to maximize the benefits utilizing the robotic surgery.
This article uses the lens of computer writing injuries to explore writing as an embodied activity. We use philosopher Mark Johnson's five-part definition of embodiment to develop an analysis that examines the physical, flesh-and-blood aspects of writing in addition to the social and cultural aspects of embodied activity. With this framework, we show the limits of purely technological solutions to writing injuries (like ergonomic keyboards) and explore the difficulties of including somatic training in the writing classroom. Rather than prescribing a single solution, we propose that these injuries require multifaceted infrastructural changes and point to the benefits of approaching writing with mindfulness. We conclude by suggesting ways that writing instructors and scholars can use this framework to rethink the role of the body in writing activity.The basis of all our forms of understanding is that given to us by our body's interactions with the world. Somatic understanding precedes all others, and persists while our symbolic forms of understanding develop, and it shapes those forms of understanding in profound and subtle ways. Understanding human cognition, then, requires our careful attentiveness to the body that is their foundation. We have attended to the body's role in our cultural lives and especially in education far too little.--Kieran Egan (2004, p. ix)
Samenvatting RSI (repetitive strain injury) houdt Nederland bezig. Er zijn aanwijzingen over het ontstaan van RSI, maar deze zijn vaak
niet sluitend of onderbouwd met wetenschappelijke literatuur. Ondanks deze hiaten in etiologische kennis, wordt RSI op alle
mogelijke denkbare manieren bestreden. Een van de maatregelen is het creëren van een ergonomisch optimale (werk)plek.
Background:
Non-surgical treatments, including ergonomic positioning or equipment, are sometimes offered to people experiencing mild to moderate symptoms from carpal tunnel syndrome. The effectiveness and duration from ergonomic positioning or equipment interventions for treating carpal tunnel syndrome are unknown.
Objectives:
To assess the effects of ergonomic positioning compared with no treatment, a placebo or another non-surgical intervention in people with carpal tunnel syndrome.
Search methods:
We searched the Cochrane Neuromuscular Disease Group Specialized Register (14 June 2011), the Cochrane Central Register of Controlled Trials (CENTRAL) (2011, Issue 2, in The Cochrane Library), MEDLINE (1966 to June 2011), EMBASE (1980 to June 2011), CINAHL Plus (1937 to June 2011), and AMED (1985 to June 2011). We also reviewed the reference lists of randomized or quasi-randomized trials identified from the electronic search.
Selection criteria:
Randomized or quasi-randomized controlled trials comparing ergonomic positioning or equipment with no treatment, placebo or another non-surgical intervention in people with carpal tunnel syndrome.
Data collection and analysis:
Two review authors independently selected trials for inclusion, extracted data and assessed risk of bias of included studies. They calculated risk ratios and mean differences with 95% confidence intervals for the primary and secondary outcomes. Results of clinically and statistically homogeneous trials were pooled, where possible, to provide estimates of the effect of ergonomic positioning or equipment.
The present study used longitudinal data from an alternative keyboard intervention study to test pathways between physical, work organization/psychosocial, stress and musculoskeletal symptom factors postulated by Sauter and Swanson in their ecological model of musculoskeletal disorders in office work. Data on work organization, stress and musculoskeletal symptoms were collected from 189 office workers at baseline and 1 year later. After baseline, an alternative keyboard was provided to half of the participants, while the remaining participants continued using a conventional keyboard. Regression analyses on the Year 1–baseline difference scores revealed significant relationships for keyboard condition and musculoskeletal symptoms, keyboard condition and work organization and work organization and stress. However, the relationships between work organization and musculoskeletal symptoms, keyboard condition and stress and stress and musculoskeletal symptoms were not significant. Thus, the analyses provided partial support for the tested pathways.
Occupational injuries pose a major problem in workplaces where computers are widely used. Intensive, repetitive and long period computer use results in costly health problems (direct cost), and lost productivity (indirect cost). Yet, the effect of musculoskeletal discomfort and their frequencies associated with the use of computers have not received considerable attention. This paper presents the findings of a risk assessment model through a scientific research to determine the effect of discomfort factors that contribute to musculoskeletal disorders resulting from intensive use of computers in the workplaces. In this context a questionnaire was given to 130 intensive computer users working in the university sector. A list of significant predictor variables for musculoskeletal disorders was developed to assess and analyze workplace ergonomics, worker attitudes and experiences on computer keyboard and mouse. The main focus of the current research is to seek and provide evidence that symptoms of musculoskeletal discomfort and the frequency of these symptoms are significant in the development of work-related musculoskeletal disorders (WRMSDs). This study provides the evidence that, ache and pain are the most common types of discomforts in all body regions. The discomforts were more pronounced at neck, shoulder, upper back, hand/wrist, and lower back regions. The risk factors determined by the risk assessment model were validated through ANOVA of the sEMG records for the control and test groups. The findings indicated that for each test group respondent, the mean musculoskeletal strain experienced differs in time, but the same is not true for the control group.
Work-related upper limb and neck musculoskeletal disorders (MSDs) are one of the most common occupational disorders around the world. Although ergonomic design and training are likely to reduce the risk of workers developing work-related upper limb and neck MSDs, the evidence is unclear.
To assess the effects of workplace ergonomic design or training interventions, or both, for the prevention of work-related upper limb and neck MSDs in adults.
We searched MEDLINE, EMBASE, the Cochrane Central Register of Controlled Trials (CENTRAL), CINAHL, AMED, Web of Science (Science Citation Index), SPORTDiscus, Cochrane Occupational Safety and Health Review Group Database and Cochrane Bone, Joint and Muscle Trauma Group Specialised Register to July 2010, and Physiotherapy Evidence Database, US Centers for Disease Control and Prevention, the National Institute for Occupational Safety and Health database, and International Occupational Safety and Health Information Centre database to November 2010.
We included randomised controlled trials (RCTs) of ergonomic workplace interventions for preventing work-related upper limb and neck MSDs. We included only studies with a baseline prevalence of MSDs of the upper limb or neck, or both, of less than 25%.
Two review authors independently extracted data and assessed risk of bias. We included studies with relevant data that we judged to be sufficiently homogeneous regarding the intervention and outcome in the meta-analysis. We assessed the overall quality of the evidence for each comparison using the GRADE approach.
We included 13 RCTs (2397 workers). Eleven studies were conducted in an office environment and two in a healthcare setting. We judged one study to have a low risk of bias. The 13 studies evaluated effectiveness of ergonomic equipment, supplementary breaks or reduced work hours, ergonomic training, a combination of ergonomic training and equipment, and patient lifting interventions for preventing work-related MSDs of the upper limb and neck in adults.Overall, there was moderate-quality evidence that arm support with alternative mouse reduced the incidence of neck/shoulder disorders (risk ratio (RR) 0.52; 95% confidence interval (CI) 0.27 to 0.99) but not the incidence of right upper limb MSDs (RR 0.73; 95% CI 0.32 to 1.66); and low-quality evidence that this intervention reduced neck/shoulder discomfort (standardised mean difference (SMD) -0.41; 95% CI -0.69 to -0.12) and right upper limb discomfort (SMD -0.34; 95% CI -0.63 to -0.06).There was also moderate-quality evidence that the incidence of neck/shoulder and right upper limb disorders were not reduced when comparing alternative mouse and conventional mouse (neck/shoulder RR 0.62; 95% CI 0.19 to 2.00; right upper limb RR 0.91; 95% CI 0.48 to 1.72), arm support and no arm support with conventional mouse (neck/shoulder RR 0.67; 95% CI 0.36 to 1.24; right upper limb RR 1.09; 95% CI 0.51 to 2.29), and alternative mouse with arm support and conventional mouse with arm support (neck/shoulder RR 0.58; 95% CI 0.30 to 1.12; right upper limb RR 0.92; 95% CI 0.36 to 2.36).There was low-quality evidence that using an alternative mouse with arm support compared to conventional mouse with arm support reduced neck/shoulder discomfort (SMD -0.39; 95% CI -0.67 to -0.10). There was low- to very low-quality evidence that other interventions were not effective in reducing work-related upper limb and neck MSDs in adults.
We found moderate-quality evidence to suggest that the use of arm support with alternative mouse may reduce the incidence of neck/shoulder MSDs, but not right upper limb MSDs. Moreover, we found moderate-quality evidence to suggest that the incidence of neck/shoulder and right upper limb MSDs is not reduced when comparing alternative and conventional mouse with and without arm support. However, given there were multiple comparisons made involving a number of interventions and outcomes, high-quality evidence is needed to determine the effectiveness of these interventions clearly. While we found very-low- to low-quality evidence to suggest that other ergonomic interventions do not prevent work-related MSDs of the upper limb and neck, this was limited by the paucity and heterogeneity of available studies. This review highlights the need for high-quality RCTs examining the prevention of MSDs of the upper limb and neck.
Background
Prolonged sitting has been associated with musculoskeletal dysfunction. For desk workers, workstation modifications frequently address the work surface and chair. Chairs which can prevent abnormal strain of the neuromuscular system may aid in preventing musculo-skeletal pain and discomfort. Anecdotally, adjustability of the seat height and the seat pan depth to match the anthropometrics of the user is the most commonly recommended intervention. Within the constraints of the current economic climate, employers demand evidence for the benefits attributed to an investment in altering workstations, however this evidence-base is currently unclear both in terms of the strength of the evidence and the nature of the chair features. The purpose of this study was to evaluate the evidence for the effectiveness of chair interventions in reducing workplace musculoskeletal symptoms.
Methods
Pubmed, Cinahl, Pedro, ProQuest, SCOPUS and PhysioFocus were searched. ‘Ergonomic intervention’, ‘chair’, ‘musculoskeletal symptoms’, ‘ergonomics’, ‘seated work’ were used in all the databases. Articles were included if they investigated the influence of chair modifications as an intervention; participants were in predominantly seated occupations; employed a pre/post design (with or without control or randomising) and if the outcome measure included neuro-musculoskeletal comfort and/or postural alignment. The risk of bias was assessed using a tool based on The Cochrane Handbook.
Results
Five studies were included in the review. The number of participants varied from 4 to 293 participants. Three of the five studies were Randomised Controlled Trials, one pre and post-test study was conducted and one single case, multiple baselines (ABAB) study was done. Three studies were conducted in a garment factory, one in an office environment and one with university students. All five studies found a reduction in self-reported musculoskeletal pain immediately after the intervention. Bias was introduced due to poor randomization procedures and lack of concealed allocation. Meta-analysis was not possible due to the heterogeneity of the data (differing population, intervention and outcomes across studies).
Conclusion
The findings of this review indicate a consistent trend that supports the role of a chair intervention to reduce musculoskeletal symptoms among workers who are required to sit for prolonged periods. However the amount, level and quality of the evidence are only moderate therefore we cannot make strong recommendations until further trials are conducted. The review also highlights gaps: for example in showing whether the effectiveness of a chair intervention has long-term impact, particularly with respect to musculoskeletal symptoms, as well as the recurrence of symptoms and the consequent cost of care.
Work Related Musculoskeletal Disorders (WMSDs) among office workers with intensive computer use is widespread and the prevalence of symptoms is growing. This randomized controlled trial investigated the effects of an office ergonomics training combined with a sit-stand workstation on musculoskeletal and visual discomfort, behaviors and performance. Participants performed a lab-based customer service job for 8 h per day, over 15 days and were assigned to: Ergonomics Trained (n = 11) or Minimally Trained (n = 11). The training consisted of: a 1.5-h interactive instruction, a sit/stand practice period, and ergonomic reminders. Ergonomics Trained participants experienced minimal musculoskeletal and visual discomfort across the 15 days, varied their postures, with significantly higher performance compared to the Minimally Trained group who had a significantly higher number of symptoms, suggesting that training plays a critical role. The ability to mitigate symptoms, change behaviors and enhance performance through training combined with a sit-stand workstation has implications for preventing discomforts in office workers.
This chapter examines ergonomic interventions for computer users who experience cumulative trauma disorders (CTDs) in the
workplace. CTDs are defined. The complex nature of these disorders and the need for holistic and comprehensive evaluation
is discussed. Statistics of prevalence and incidence are reviewed. The role of occupational therapy in the management of these
disorders is examined. Examples of interventions for these disorders are cited, and a systematic review of the effectiveness
of the ergonomic interventions is provided. Finally, recommendations for occupational therapy practice and further research
are provided.
KeywordsComputers–Cumulative trauma disorders–Ergonomics–Musculoskeletal disorders
Objective:
The aim of this study was to investigate the effects of an EMG-based feedback device on the human musculoskeletal system by assessing the kinematics of the lumbar and cervical regions during computer operation.
Methods:
Using an EMG device, measurements were collected under four conditions: with feedback from the upper trapezius muscle, from the L4-erector spinae muscles and from both and without feedback (control). During periods of 15 min of computer operation, kinematic data were collected using the Zebris motion analysis system to investigate 14 university employees.
Results:
Feedback assessment effectively reduced the kinematic changes in the sagittal plane compared with the control (p<0.05). Feedback from the L4 erector spinae reduced the trunk flexion and forward head angles, which were significantly different compared with those under the feedback from the upper trapezius and the control conditions (p<0.05).
Conclusion:
We observed that the use of an EMG-based feedback device was effective in reducing habitual forward head and flexed-relaxed postures during computer operation. Additionally, posture correction from the lumbar region could be a way to reduce forward head posture as well as flexed-relaxed posture.
This is the protocol for a review and there is no abstract. The objectives are as follows:
To assess the effects of workplace ergonomic design and/or training interventions for the prevention of work-related musculoskeletal disorders of the upper limb and neck in adults.
This review aims to make the following main comparisons:
1. Ergonomically designed equipment or environmental interventions versus no or placebo intervention;
2. Ergonomically designed equipment or environmental intervention versus another intervention;
3. Ergonomic training versus no or placebo training; and
4. A combination of ergonomically designed equipment or environmental interventions or ergonomic training versus a single intervention or a different combination of interventions.
Problem: Although alternative keyboards promote safer postures, their implementation is impeded by the initial reduced productivity. The objective of this study was to assess the effect of training on typing efficiency on two ergonomic keyboards (Maltron and Goldtouch).Method: Thirty volunteers (20 trained and 10 untrained) typed a standardized text on each keyboard. Bilateral wrist motion, overall applied force, surface electromyography (EMG), and typing performance were continuously monitored.Results: The one-way ANOVA with repeated measures revealed that training decreased the applied force significantly for both Maltron (p<0.031) and Goldtouch (p<0.022). Training affected the typing speed (p<0.027 and p<0.008 for Goldtouch and Maltron, respectively) and error rate (p<0.039 and p<0.007 for Goldtouch and Maltron, respectively). However, training did not influence wrist motion and EMG muscle activity.Conclusions: Due to the fact that the increase in performance following the training period did not cause higher muscle activity, ergonomic keyboards may constitute a solution for reducing typing related musculoskeletal problems.Relevance to industryWhile ergonomic keyboards have been developed in order to reduce the computer work-related injuries, their introduction has been delayed due to economic reasons. Proving that after a relative short training session, the majority of typing parameters have improved would increase the acceptance of new devices in the workplace.
Background:
Non-surgical treatment, including ergonomic positioning or equipment, are sometimes offered to people experiencing mild to moderate symptoms from carpal tunnel syndrome (CTS). The effectiveness and duration of benefit from ergonomic positioning or equipment interventions for treating CTS are unknown.
Objectives:
To assess the effects of ergonomic positioning or equipment compared with no treatment, a placebo or another non-surgical intervention in people with CTS.
Search methods:
We searched the Cochrane Neuromuscular Disease Group Specialized Register (14 June 2011), the Cochrane Central Register of Controlled Trials (CENTRAL) (2011, Issue 2, in The Cochrane Library), MEDLINE (1966 to June 2011), EMBASE (1980 to June 2011), CINAHL Plus (1937 to June 2011), and AMED (1985 to June 2011). We also reviewed the reference lists of randomised or quasi-randomised trials identified from the electronic search.
Selection criteria:
Randomised or quasi-randomised controlled trials comparing ergonomic positioning or equipment with no treatment, placebo or another non-surgical intervention in people with CTS.
Data collection and analysis:
Two review authors independently selected trials for inclusion, extracted data and assessed risk of bias of included studies. We calculated risk ratios (RR) and mean differences (MD) with 95% confidence intervals (CI) for the primary and secondary outcomes. We pooled results of clinically and statistically homogeneous trials, where possible, to provide estimates of the effect of ergonomic positioning or equipment.
Main results:
We included two trials (105 participants) comparing ergonomic versus placebo keyboards. Neither trial assessed the primary outcome (short-term overall improvement) or adverse effects of interventions. In one small trial (25 participants) an ergonomic keyboard significantly reduced pain after 12 weeks (MD -2.40; 95% CI -4.45 to -0.35) but not six weeks (MD -0.20; 95% CI -1.51 to 1.11). In this same study, there was no difference between ergonomic and standard keyboards in hand function at six or 12 weeks or palm-wrist sensory latency at 12 weeks. The second trial (80 participants) reported no significant difference in pain severity after six months when using either of the three ergonomic keyboards versus a standard keyboard. No trials comparing (i) ergonomic positioning or equipment with no treatment, (ii) ergonomic positioning or equipment with another non-surgical treatment, or (iii) different ergonomic positioning or equipment regimes, were found.
Authors' conclusions:
There is insufficient evidence from randomised controlled trials to determine whether ergonomic positioning or equipment is beneficial or harmful for treating carpal tunnel syndrome.
The complexity of some newer product interaction in complex context systems demands a higher level of user performance and involves risk that may possibly negatively impact the user’s safety and health. For this reason, the evaluation or design of new products used in complex systems requires extensive knowledge of human interaction, including the operation and vulnerabilities of the whole system. Therefore, with this consideration, the use of video analysis increases the capability to collect more detailed information on human activity during the interaction of the user with a product-environment system. With these data come increased understanding of user strategies and awareness of possible safety and health issues and system dysfunctions.
To compare the effects of biofeedback with those of active exercise and passive treatment in treating work-related neck and shoulder pain.
A randomized controlled trial with 3 intervention groups and a control group.
Participants were recruited from outpatient physiotherapy clinics and a local hospital.
All participants reported consistent neck and shoulder pain related to computer use for more than 3 months in the past year and no severe trauma or serious pathology. A total of 72 potential participants were recruited initially, of whom a smaller group of individuals (n=60) completed the randomized controlled trial.
The 3 interventions were applied for 6 weeks. In the biofeedback group, participants were instructed to use a biofeedback machine on the bilateral upper trapezius (UT) muscles daily while performing computer work. Participants in the exercise group performed a standardized exercise program daily on their own. In the passive treatment group, interferential therapy and hot packs were applied to the participants' necks and shoulders. The control group was given an education booklet on office ergonomics.
Pain (visual analog scale), neck disability index (NDI), and surface electromyography were assessed preintervention and postintervention. Pain and NDI were reassessed after 6 months.
Postintervention, average pain and NDI scores were reduced significantly more in the biofeedback group than in the other 3 groups, and this was maintained at 6 months. Cervical erector spinae muscle activity showed significant reductions postintervention in the biofeedback group, and there were consistent trends of reductions in the UT muscle activity.
Six weeks of biofeedback training produced more favorable outcomes in reducing pain and improving muscle activation of neck muscles in patients with work-related neck and shoulder pain.
To describe the range of ergonomic stressors and effective interventions in otherwise healthy patients diagnosed with upper extremity disorders associated with occupational keyboard/mouse use.
From patients treated in our Medical-Ergonomic Program, we report demographic data, symptoms, signs, diagnoses and associated ergonomic stressors and response to medical/ergonomic interventions.
Fifty-six patients had a mean age (range) of 40 (23-61) years with 20 patients younger than 35 years. The most prevalent diagnoses were myofascial pain syndrome (MPS) of shoulder/neck associated with poor posture, MPS of forearm extensors followed by thoracic outlet syndrome and carpal tunnel syndrome. Common ergonomic stressors were typing/mousing technique, keyboard height, inadequate seating, and lack of breaks. Improvement occurred in 89% following medical/ergonomic intervention.
Ergonomic education/intervention must be combined with the medical treatment of work-related upper extremity disorders associated with keyboard/mouse use.
Upper limb pain is common among working-aged adults and a frequent cause of absenteeism.
To systematically review the evidence for workplace interventions in four common upper limb disorders.
Systematic review of English articles using Medline, Embase, Cinahl, AMED, Physiotherapy Evidence Database PEDro (carpal tunnel syndrome and non-specific arm pain only) and Cochrane Library. Study inclusion criteria were randomized controlled trials, cohort studies or systematic reviews employing any workplace intervention for workers with carpal tunnel syndrome, non-specific arm pain, extensor tenosynovitis or lateral epicondylitis. Papers were selected by a single reviewer and appraised by two reviewers independently using methods based on Scottish Intercollegiate Guidelines Network (SIGN) methodology.
1532 abstracts were identified, 28 papers critically appraised and four papers met the minimum quality standard (SIGN grading + or ++) for inclusion. There was limited evidence that computer keyboards with altered force displacement characteristics or altered geometry were effective in reducing carpal tunnel syndrome symptoms. There was limited, but high quality, evidence that multi-disciplinary rehabilitation for non-specific musculoskeletal arm pain was beneficial for those workers absent from work for at least four weeks. In adults with tenosynovitis there was limited evidence that modified computer keyboards were effective in reducing symptoms. There was a lack of high quality evidence to inform workplace management of lateral epicondylitis.
Further research is needed focusing on occupational management of upper limb disorders. Where evidence exists, workplace outcomes (e.g. successful return to pre-morbid employment; lost working days) are rarely addressed.
To review literature systematically concerning effectiveness of nonsurgical interventions for treating carpal tunnel syndrome (CTS).
The Cochrane Library, PubMed, EMBASE, CINAHL, and PEDro were searched for relevant systematic reviews and randomized controlled trials (RCTs).
Two reviewers independently applied the inclusion criteria to select potential studies.
Two reviewers independently extracted the data and assessed the methodologic quality.
A best-evidence synthesis was performed to summarize the results of the included studies. Two reviews and 20 RCTs were included. Strong and moderate evidence was found for the effectiveness of oral steroids, steroid injections, ultrasound, electromagnetic field therapy, nocturnal splinting, and the use of ergonomic keyboards compared with a standard keyboard, and traditional cupping versus heat pads in the short term. Also, moderate evidence was found for ultrasound in the midterm. With the exception of oral and steroid injections, no long-term results were reported for any of these treatments. No evidence was found for the effectiveness of oral steroids in long term. Moreover, although higher doses of steroid injections seem to be more effective in the midterm, the benefits of steroids injections were not maintained in the long term. For all other nonsurgical interventions studied, only limited or no evidence was found.
The reviewed evidence supports that a number of nonsurgical interventions benefit CTS in the short term, but there is sparse evidence on the midterm and long-term effectiveness of these interventions. Therefore, future studies should concentrate not only on short-term but also on midterm and long-term results.
Amitriptyline is sometimes used to treat arm pain related to repetitive use, but rigorous evidence of its benefit is lacking. This randomized controlled trial investigated whether amitriptyline provided greater pain relief or improved arm function than a placebo pill in adults with arm pain associated with repetitive use that had persisted for at least 3 months. Participants (N=118) were randomly assigned to receive 25mg of amitriptyline or a placebo pill for 6 weeks. The primary outcome was intensity of pain (10-point numerical rating scale) and secondary outcomes were arm symptoms, arm function, grip strength, mood, and sleep. Assessments were done at baseline, 3 and 6 weeks of treatment, and 1 month after the treatment ended. Changes in arm pain were not statistically significant. However, the amitriptyline group improved more than the placebo group in arm function (p=0.023) and sense of well being (p=0.034). In a longitudinal analysis, the amitriptyline group's arm function score improved 0.45 points per week faster than placebo after adjusting for subject characteristics (p=0.015). At the treatment's midpoint, the amitriptyline group reported more "troublesome side-effects" than the placebo group (52.5% vs. 27.1%, p=0.005), but this difference decreased by the end of the treatment (30.5% vs. 22.0%, p=0.30). The most frequent side effect was drowsiness. In conclusion, this study found that low-dose amitriptyline did not significantly decrease arm pain among these participants but did significantly improve arm function and well being. Future research is needed to explore the effects of higher doses and longer duration of treatment.
Conventional, straight keyboards remain the most popular design among keyboards sold and used with personal computers despite the biomechanical benefits offered by alternative keyboard designs. Some typists indicate that the daunting medical device-like appearance of these alternative 'ergonomic' keyboards is the reason for not purchasing an alternative keyboard design. The purpose of this research was to create a new computer keyboard that promoted more neutral postures in the wrist while maintaining the approachability and typing performance of a straight keyboard. The design process created a curved alphanumeric keyboard, designed to reduce ulnar deviation, and a built-in, padded wrist-rest to reduce wrist extension. Typing performance, wrist postures and perceptions of fatigue when using the new curved keyboard were compared to those when using a straight keyboard design. The curved keyboard reduced ulnar deviation by 2.2 degrees +/- 0.7 (p < 0.01). Relative to the straight keyboard without a built-in wrist-rest, the prototype curved keyboard with the built-in padded wrist-rest reduced wrist extension by 6.3 degrees +/- 1.2 (p < 0.01). There were no differences in typing speed or accuracy between keyboards. Perceived fatigue ratings were significantly lower in the hands, forearms and shoulders with the curved keyboard. The new curved keyboard achieved its design goal of reducing discomfort and promoting more neutral wrist postures while not compromising users' preferences and typing performance.
Questionnaire-based measures of function have been validated extensively in studies of chronic illness and work-related low back pain. These measures have only recently been developed for upper extremity disorders (UEDs), and there is little information on their utility in evaluation of injured workers. We developed the Upper Extremity Function Scale (UEFS), an eight-item, self-administered questionnaire, to measure the impacts of UEDs on function. This instrument was tested in a cohort of 108 patients with work-related UEDs and 165 patients with the carpal tunnel syndrome (CTS); both groups were enrolled in prospective follow-up studies. The UEFS demonstrated excellent psychometric properties, including good internal consistency (Cronbach's alpha > 0.83), relative absence of floor effects, and excellent convergent and discriminant validity, compared with measures of symptom severity and clinical findings. In the CTS group, the UEFS was more responsive to significant improvements over time than clinical measures such as grip and pinch strength. These data support the use of a self-reported functional scale as a measure of outcome in studies of work-related UEDs. Further investigations in working populations are needed to substantiate its utility in workers with UEDs who have not yet sought medical care.
Cumulative trauma disorders due to performance of repetitive tasks account for more than 50% of all occupational illnesses in the United States today. Employees affected by these disorders frequently experience substantial pain and functional impairment that may require a change in occupation. For the employer, these injuries result in loss of productivity and increased costs in the form of higher medical expenses and disability payments for injured workers. Successful treatment of work-related repetitive tissue injuries depends on early diagnosis and appropriate therapy. Prevention requires identifying sites and tasks that place employees at risk of injury and supporting efforts to develop safer work environments.
The association between specific job characteristics and subsequent cardiovascular disease was tested using a large random sample of the male working Swedish population. The prospective development of coronary heart disease (CHD) symptoms and signs was analyzed using a multivariate logistic regression technique. Additionally, a case-controlled study was used to analyze all cardiovascular-cerebrovascular (CHD-CVD) deaths during a six-year follow-up. The indicator of CHD symptoms and signs was validated in a six-year prospective study of CHD deaths (standardized mortality ratio 5.0; p less than or equal to .001). A hectic and psychologically demanding job increases the risk of developing CHD symptoms and signs (standardized odds ratio 1.29, p less than 0.25) and premature CHD-CVD death (relative risk 4.0, p less than .01). Low decision latitude-expressed as low intellectual discretion and low personal schedule freedom-is also associated with increased risk of cardiovascular disease. Low intellectual discretion predicts the development of CHD symptoms and signs (SOR 1.44, p less than .01), while low personal schedule freedom among the majority of workers with the minimum statutory education increases the risk of CHD-CVD death (RR 6.6, p less than .0002). The associations exist after controlling for age, education, smoking, and overweight.
This paper presents a conceptual model for the pathogenesis of work-related musculoskeletal disorders. The model contains sets of cascading exposure, dose, capacity, and response variables, such that response at one level can act as dose at the next. Response to one or more doses can diminish or increase the capacity for responding to successive doses. The model is used as a framework for discussing the development of work-related muscle, tendon, and nerve disorders. It is intended as a beginning, to be modified to explain new findings as they become available. In research, it can help to identify areas needing additional data for the development and expression of work-related musculoskeletal disorders. Researchers can use it to design laboratory and field studies. In practice, it demonstrates the relationship between common exposure factors and different responses. This information can be used to evaluate and design jobs for the prevention of work-related musculoskeletal disorders.
Questionnaire-based measures of function have been validated extensively in studies of chronic illness and work-related low back pain. These measures have only recently been developed for upper extremity disorders (UEDs), and there is little information on their utility in evaluation of injured workers. We developed the Upper Extremity Function Scale (UEFS), an eight-item, self-administered questionnaire, to measure the impacts of UEDs on function. This instrument was tested in a cohort of 108 patients with work-related UEDs and 165 patients with the carpal tunnel syndrome (CTS); both groups were enrolled in prospective follow-up studies. The UEFS demonstrated excellent psychometric properties, including good internal consistency (Cronbach's alpha > 0.83), relative absence of floor effects, and excellent convergent and discriminant validity, compared with measures of symptom severity and clinical findings. In the CTS group, the UEFS was more responsive to significant improvements over time than clinical measures such as grip and pinch strength. These data support the use of a self-reported functional scale as a measure of outcome in studies of work-related UEDs. Further investigations in working populations are needed to substantiate its utility in workers with UEDs who have not yet sought medical care.
This study presents an evaluation of an adjustable keyboard based on subjective preference and wrist joint motion during typing. Thirty-five computer users used the adjustable split design keyboard for 7-14 days during their usual work and were instructed to adjust the keyboard to the opening angle they preferred. At the end of this period, three-dimensional motion analysis was performed to compare the distribution of wrist joint angles while subjects typed on a conventional keyboard and the adjustable keyboard adjusted to the subject's preferred angle. The mean preferred opening angle was 14 degrees +/- 10. The mean ulnar deviation of the subjects who selected the opening angles between 21 and 28 degrees (n = 12) decreased from 18 degrees +/- 5 on the flat to 14 degrees +/- 5 on the adjustable (p < 0.05), while those who selected 0 to 10 degrees (n = 6) and 11 to 20 degrees (n = 17) split angles showed no significant differences in ulnar deviation. Mean wrist extension on the adjustable keyboard was 17 degrees +/- 5 and was significantly less than the 24 degrees +/- 5 observed on the conventional keyboard and most likely due to the presence of palm support. On average, subjects reported that the adjustable keyboard was more comfortable (0.5 +/- 0.5) (worse = -1, same = 0, better, = 1) in comparison with the conventional keyboard.
General Introduction Anatomy of the Spine Vasculature of the Spine Basic neurology Upper / Lower motor neuron disease testing musculature reflex sensation, temperature, pain, vibration, and grading systems cervical eye examination thoracic spine examination lumbar examination
This study utilizes a variable geometry keyboard to analyze the optimal configuration for a split QWERTY-type keyboard. The measured criteria were muscle activity as measured by EMG and reported operator discomfort. A variable geometry keyboard, simultaneously adjustable in opening angle (yaw) and lateral angle (roll) was obtained. The upward slope (tilt) was preset at 10%. The study manipulated the keyboard geometry to assess the difference in musculoskeletal activity between using (1) a conventional, flat, linear keyboard; (2) a neutral, undeviated wrist position; and (3) two forearm positions that essentially eliminate pronation. Eight experienced subjects with no prior history of wrist injury or other pathology were tested. EMG activity of four relevant muscle groups was measured on each subject for each of the four keyboard positions. The study suggested an 18° opening angle and a 30°–60° lateral angle as optimal when compared with a flat, standard keyboard (they minimize objective EMG activity and subjective discomfort).
Twenty experienced typists participated in a laboratory based study to determine whether wrist and forearm postures changed over a 4 hour period of intensive keyboard use. Subjects were randomly assigned to use a conventional keyboard or a fixed split keyboard. Posture data was acquired using electrogoniometers after a 10 warm-up period and at the end of each hour. Wrist and forearm postures did not change significantly over the four hour period among subjects using the split geometry keyboard. On the conventional keyboard, all joint postures were stable except right wrist extension and left forearm pronation. The right wrist extension increased by 5° over the four hour period (p=.002) and left pronation decreased by approximately 9° (p=.001). Wrist postures among typists exposed for the first time to a split keyboard remained constant throughout a four hour period of intensive typing. On the conventional keyboard, some postures drifted over the four hour period.
Fifty experienced typists participated in a laboratory based repeated measures study with two factors: keyboard height (three) and keyboard configuration (three). The work surface heights tested were 63, 67 and 71 cm. The three keyboard configurations tested were: standard (Apple Extended™), alternative keyboard A (Microsoft Natural Keyboard) and alternative keyboard B (equivalent to Natural Keyboard with Leveler™ extended). Wrist and forearm posture data was acquired using electronic goniometers during 10 minutes of typing at each keyboard/height level. Across all heights tested, wrist extension, wrist ulnar deviation, and forearm pronation were statistically significantly closer to neutral when using alternative keyboard B than when using the standard keyboard.
Video display terminal (VDT) operators (n = 150) in the editorial department of a large metropolitan newspaper participated in a study of day-to-day musculoskeletal symptoms. Work posture related to the VDT workstation and psychosocial work factors were also investigated for their contributions to the severity of upper body pain, numbness, and stiffness using a representative subsample (n = 70). Self-report measures included Karasek's Job Content Instrument and the author-designed Work Interpersonal Relationships Inventory. Independent observations of work posture were performed using techniques similar to those reported by Sauter et al. [1991]. Pain during the last week was reported by 59% (n = 88) of the respondents, and 28% (n = 42) were categorized by symptom criteria potentially to have musculoskeletal disorders. More hours per day of VDT use and less decision latitude on the job were significant risk factors for potential musculoskeletal CTDs. Head rotation and relative keyboard height were significantly related to more severe pain and stiffness in the shoulders, neck, and upper back. Lower levels of co-worker support were associated with more severe hand and arm numbness. For both the region of the shoulders, neck, and upper back and the hand and arm region, however, the contributions of relative keyboard and seat back heights to symptom severity were modified by psychological workload, decision latitude, and employee relationship with the supervisor. Alternative explanations for these findings are discussed.
The objective of this research project was to compare two different computer keyboard designs with respect to their effect on the extent of muscular loading in the right and left trapezius and extensor muscles during typing. The two computer keyboards used in this study were (1) a classic or standard keyboard, and (2) a split‐design keyboard. Evaluation of muscular loading was done using the electromyography (EMG) technique and subjective ratings of muscular tension. Sixteen women, between 18 and 26 years of age, with similar secretarial experience and limited typing abilities, took voluntary part in the experiment. Each subject used both keyboards for 15 min. The EMG signals recorded during typing sessions were those of the left and right sides of trapezius (m. trapezius pars descendeus) and extensor (m. extensor carpi radialis brevis et longus) muscles. Upon completion of each task, subjects were asked to evaluate perceived levels of muscular tension in the shoulder‐neck area and forearms. The results showed that the split‐design computer keyboard significantly reduces muscular loading of the trapezius muscle and subjective feelings of muscular tension in the shoulder‐neck area.
The acceptance of a split keyboard with a user-adjustable angle (adjustable keyboard) and its impact on postural discomfort and general comfort of users was tested in a comparative laboratory experiment with 26 typists as subjects. The comparison was made with a standard keyboard. The results were interpreted using the findings of an earlier field study with another split keyboard with a fixed angle between the halves of the device. Both split keyboards improved postural comfort; however, the period of familiarization was much longer with the fixed-angle split keyboard. Since the adjustable keyboard allows a change, in the angle from 0 to 30-degrees, a person's posture can be adopted on a step-by-step basis. Thus, the new adjustable design has much better prospects of being accepted in practice than former attempts where the value was more academic than practical. The analysis of throughput and errors, under self-determined angles of the test object and with an angle comparable with those of fixed-angle split keyboards, reveals that users in work situations are not likely to accept fixed-angle split keyboards (30-degrees) since throughput is substantially reduced during the long period of familiarization, accompanied by a substantial increase in errors. The results of this study confirm the assumption that new adjustable split keyboard design, once accepted by the users, may improve postural comfort, general comfort, and reduce fatigue. These effects could be demonstrated both in a short-term experiment and a long-term field study. The basic design feature of the adjustable keyboard, adjustability, is in agreement with the conclusions of recent studies on the introduction of ergonomically designed keyboards.
Abstract. Thesis (M.S.)--Auburn University, 1992. Vita. Includes bibliographical references (leaves 57-61).
Although common and frequently transitory, tendonitis in the upper extremity may be quite disabling and resistant to treatment. The physician's best hope for a swift and successful resolution lies in a careful history of all possible precipitating causes and a precise localization of symptoms to obtain an exact diagnosis.
A keyboard concept based on biomechanical considerations was studied with 51 trained typists. The keyboard is split into two half-keyboards. An adjustable model allowed study of the preferred settings of opening angles, lateral inclinations, and distances of the split keyboard. The preferred split keyboards decrease the lateral deviation of the hands, and the use of a large forearm-wrist support is associated with a backwards leaning of the subjects and with an increased pressure of forearm-wrists onto the support. After the typing tasks, about two-thirds of the subjects asserted that they preferred the split keyboard models. Less pain and an increased feeling of relaxation were reported by the subjects when operating the split keyboards.
A trial of physiotherapy for muscle incoordination and aching (occupational cramp and myalgia) in teleprinter operators revealed an association between these types of symptoms of operating difficulty and disadvantageous operating postures, which in turn were thought to be related to keyboard layout. The purpose of this paper is to analyse the relationship between posture and symptoms. Subjects of symptoms and unaffected operators were interviewed, tested in various ways, and observed in teleprinter operating. Adverse operating postures of arm and hand were, with the exception of two types of posture, more often right than left sided (when they were not bilateral) and commoner in subjects than controls. Every part of the upper limb which was a site of symptoms in operating was more often affected on the right side than the left (when not bilaterally affected). Part of limb affected was usually associated with some adverse operating posture of that region. It was concluded that keyboard design and work height predispose to operating postures which in some operators give rise to symptoms in operating.
The standard typewriter keyboard serves as a model for keyboards of teletypewriters, desk calculators, consoles, computer keysets, cash registers, etc. This man-machine interface should be designed to allow high-frequency, error-free operation with the least possible strain on the operator. This paper discusses several feasible biomechanical improvements of the keyboard. Some experimental findings are described which support the following design concepts: (1) the keys should be arranged in a “hand-configured” grouping to simplify the motion patterns of the fingers; (2) the keyboard sections allotted to each hand should be physically separated to facilitate the positioning of the fingers; and (3) the keyboard sections allotted to each hand should be declined laterally to reduce postural muscular strain of the operator.
Relationships between visual display terminal (VDT) use and musculoskeletal problems were examined in a group of 353 office workers, using data from medical and workplace investigations as well as questionnaires. There were no general differences between VDT and non-VDT users as to the occurrence of muscle problems. Combinations of specific VDT work situations such as data entry work or work with a VDT for more than 20 h/week and the presence of some other factors were, however, associated with excess risks of certain muscle problems. The extraneous factors involved in the definitions of such risk groups were: use of bifocal or progressive glasses at a VDT; stomach-related stress reactions; limited rest break opportunity; repetitive movements; non-use of lower arm support; and possibly the vertical position of the keyboard; and presence of specular glare.
This paper considers one way that occupational health professionals can assess the force exerted by keyboard users and the possible relationship between that force and the key force-displacement relationship. First, three personal-computer keyboards with the standard QWERTY layouts were tested as described by the American National Standard for Human Factors Engineering of Visual Display workstations (ANSI/HFS 100-1988) to determine the peak forces, 0.47-0.89N; displacements prior to the "breakaway" force that acknowledges key registration, 2.0-2.5 mm; and total key travel, 3.3-4.3 mm. Second, keyboard reaction forces were recorded while 10 subjects typed 4 alphanumeric sentences on the keyboards. It was found that the peak forces corresponding to each keystroke were 2.5 to 3.9 times the required activation forces, indicating that the subjects consistently displaced the keys to their limits. The average of the peak forces for all keystrokes was lowest for the keyboard with the lowest required activation force. It was concluded that keyboard reaction forces can be used as an index of finger forces for keying tasks. Further studies are necessary to evaluate the relationship between keyboard reaction forces, fatigue, and chronic muscle, tendon, and nerve disorders.
This study investigated how ergonomic design influences neck-and-shoulder muscle strain, through keyboard assessment. Muscular activity was measured electromyographically (EMG) from six muscles in the forearm and shoulders of eight experienced typists using each of five different types of keyboard: one mechanical, one electromechanical, and one electronic typewriter; one personal computer/word processor (PC-XT) keyboard; and one angled at 20 degrees in the horizontal plane. The impact on muscular activity of using a palmrest was also studied. The mechanical typewriter induced a higher strain in the forearm and finger muscles than did the modern typewriters and keyboards. These induced no different strain on the neck-and-shoulder muscles, except for the right shoulder muscle, which was more active with the electronic typewriter than with the other machines. Using a palmrest did not decrease the strain on the muscles investigated. Use of the 'angled' PC-XT keyboard did not influence the measured muscular load on the forearm and finger muscles compared to typing on an ordinary PC-XT keyboard, but decreased the extensor muscular strain compared to the electronic typewriter.
We developed a self-administered questionnaire for the assessment of severity of symptoms and functional status in patients who have carpal tunnel syndrome. The reproducibility, internal consistency, validity, and responsiveness to clinical change of scales for the measurement of severity of symptoms and functional status were evaluated in a clinical study. The scales were highly reproducible (Pearson correlation coefficient, r = 0.91 and 0.93 for severity of symptoms and functional status, respectively) and internally consistent (Cronbach alpha, 0.89 and 0.91 for severity of symptoms and functional status, respectively). Both scales had positive, but modest or weak, correlations with two-point discrimination and Semmes-Weinstein monofilament testing (Spearman coefficient, r = 0.12 to 0.42). In thirty-eight patients who were operated on in 1990 and were evaluated a median of fourteen months postoperatively, the mean symptom-severity score improved from 3.4 points preoperatively to 1.9 points at the latest follow-up examination, while the mean functional-status score improved from 3 to 2 points (5 points is the worst score and 1 point is the best score for each scale). Similar improvement was noted in twenty-six patients who were evaluated before and three months after the operation. We concluded that the scales for the measurement of severity of symptoms and functional status are reproducible, internally consistent, and responsive to clinical change, and that they measure dimensions of outcomes not captured by traditional measurements of impairment of the median nerve. These scales should enhance standardization of measurement of outcomes in studies of treatment for carpal tunnel syndrome.
In this article a basic distinction is made between etiologic and prevention effectiveness intervention studies. Etiologic intervention studies focus on elucidating causes of disease, while the purpose of prevention effectiveness intervention studies is to study methods of prevention. The design requirements for each of these studies are very different: etiologic intervention studies usually need large study populations, large exposure contrasts, ascertainment of exposure, as well as health outcome. Ideally, randomization and blinding should also be applied. Effective preventive strategies may, on the other hand, be identified in small study populations with exposure as the only outcome measure, and randomization and blinding may be superfluous. At present, intervention studies are in great demand, and often there is a wish that etiologic questions as well as prevention effectiveness be addressed in the same study. We argue that this should not be done without careful consideration of possible conflicting design aspects.
The relationships between musculoskeletal symptoms and both video display terminal (VDT) use and occupational psychosocial stress were assessed among women office workers by self-administered questionnaires. Significantly increased odds ratios for neck or shoulder symptoms were observed for subjects who had ever used a VDT, had less job security, and had more stressful work during the 2 weeks prior to completion of the questionnaire. Significantly increased odds ratios for arm and hand symptoms were observed for subjects who had used a VDT for more than 6 years, reported a very crowded workplace, or reported very stressful work during the 2 weeks prior to completion of the questionnaire. Among current non-users, those who previously used VDTs were more likely to report upper extremity musculoskeletal symptoms than those who had never used VDTs. This suggests that individuals with symptoms may be more likely to reduce their VDT usage, distorting results of cross-sectional studies.
Concerns have arisen that the keyboard is a causal factor in the development of work-related musculoskeletal disorders (WRMDs) among video display terminal (VDT) operators. A number of alternative keyboard designs have been developed with altered geometry in an effort to improve comfort in keyboard operation. However, few data are available to substantiate whether these new keyboard designs are actually effective in reducing discomfort and musculoskeletal problems in users. The purpose of this study was to provide data on the efficacy of certain alternative keyboard design features (e.g. splitting the keyboard in half, and laterally inclining the keyboard halves) in reducing fatigue and musculoskeletal discomfort among keyboard operators. The study also explored the effects of these design features on performance. Fifty subjects performed a text-entry task for one day on a standard keyboard, then were assigned to one of five keyboard conditions for an evaluation period of two days (i.e. 10 subjects/condition). Outcome measures included performance (i.e. keystrokes/h, errors/h) and self-report measures of discomfort and fatigue. The results indicated an initial decline in productivity when subjects began typing on two of the alternative keyboards, but these productivity losses were recovered within the two-day evaluation period. The results also indicated no significant differences between keyboard conditions in discomfort and fatigue. These results suggest a minimal impact of the keyboard design features examined in this study on productivity, comfort and fatigue, at least after two days of exposure.
This randomized clinical trial evaluated the effects of keyboard keyswitch design on computer users with hand paresthesias. Twenty computer users were matched and randomly assigned to keyboard A (n = 10) or B (n = 10). The keyboards were of conventional layout and differed in keyswitch design. Various outcome measures were assessed during the 12 weeks of use. Subjects assigned keyboard A experienced a decrease in hand pain between weeks 6 and 12 when compared with keyboard B subjects (P = 0.05) and demonstrated an improvement in the Phalen test time (right hand, P = 0.006; left hand, P = 0.06). Keyboard assignment had no significant effect on change in hand function or median nerve latency. We conclude that use of keyboard A for 12 weeks led to a reduction in hand pain and an improved physical examination finding when compared with keyboard B. There was no corresponding improvement in hand function or median nerve latency.
The physiologically tolerable range of positions for the joints of the upper extremities have been investigated for typing tasks by recording the myoelectric activities of the involved muscles. For long-term typing tasks a split keyboard is recommended allocating a key field to each hand. The fields should be rotated against each other in the horizontal plane and inclined laterally.
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