The effect of shaped wheelchair cushion and lumbar supports on under-seat pressure,comfort, and pelvic rotation

Aim. A wheelchair seat and position help clients perform daily activities. The comfort of the wheelchair can encourage clients to participate in daily activities and can help prevent future complications.

Purpose. This study evaluates how a shaped seat-cushion and two different back supports affect under-seat pressure, comfort, and pelvic rotation.

Method. Thirty healthy subjects were tested using two differently equipped manual wheelchairs. One wheelchair had a Velcro? adjustable back seat and a plane seat-cushion. The other wheelchair had a non-adjustable sling-back seat and a plane cushion. The second wheelchair was also equipped with a shaped cushion and/or a detachable lumbar support. Under-seat pressure, estimated comfort, and pelvic rotation were measured after 10 min in each wheelchair outfit.

Results. Peak pressure increased with the shaped cushion compared to the plane cushion. No significant difference in estimated comfort was found. Pelvic posterior-rotation was reduced with the adjustable or detachable back-support irrespective of the shape of the seat cushion.

Conclusions. To support a neutral pelvic position and spinal curvature, a combination of a shaped cushion and a marked lumbar support is most effective.     

Evaluation of a participatory ergonomic intervention aimed at improving musculoskeletal health

BACKGROUND: Participatory ergonomic (PE) interventions have been increasingly utilized to deal with work-related musculoskeletal disorders (WMSD). METHODS: Using a longitudinal quasi-experimental design, a PE process was launched at one depot of a large courier company, with a nearby depot serving as a control. Evaluations focused on 122 employees across the two depots who participated in both pre- and post-questionnaires. An evaluation framework assessed the process of implementation, changes in risk factors, and changes in musculoskeletal health outcomes. Partial and multiple regressions explored the relationships in the evaluation framework. RESULTS: Changes in work organizational factors had a consistent impact upon changes in health outcomes. Greater participation in the process was associated with increased levels of job influence and communication (P = 0.0059 and P = 0.0940 respectively). Improvements in communication levels were associated with reduced pain intensity and improved work role function (WRF) (P = 0.0077 and P = 0.0248 respectively). Lower levels of pain post-intervention were related to greater WRF (P = 0.0493). CONCLUSIONS: A PE approach can improve risk factors related to WMSD, and meaningful worker participation in the process is an important aspect for the success of such interventions.     

Working Postures: A Literature Review

Working postures are addressed in many papers in the ergonomics field but, surprisingly, scientific literature dealing with working posture itself is not common; knowledge has been elusive. This article reviews the working postures literature. Selected papers published in the English language before March 2003 including the phrase "working postures" in the title, abstract, or keywords were searched in the PubMed, Scirus, and Science Direct databases and reviewed. The literature provides evidence that working postures and musculoskeletal health are related. This relationship is supported by the overexertion, differential fatigue, and cumulative load theories of musculoskeletal injuries' precipitation. Goniometers, inclinometers, photographic techniques, electrogoniometers, and video recording systems are the means that are most often used to measure working postures. Information about working postures need to be collected and analyzed in a more systematic way in order to contribute for a deeper understanding of the relationship between working postures and work-related musculoskeletal disorders. This information will help to improve the control and rehabilitation of these highly prevalent disorders.     

Computer vision syndrome: a review

As computers become part of our everyday life, more and more people are experiencing a variety of ocular symptoms related to computer use. These include eyestrain, tired eyes, irritation, redness, blurred vision, and double vision, collectively referred to as computer vision syndrome. This article describes both the characteristics and treatment modalities that are available at this time. Computer vision syndrome symptoms may be the cause of ocular (ocular-surface abnormalities or accommodative spasms) and/or extraocular (ergonomic) etiologies. However, the major contributor to computer vision syndrome symptoms by far appears to be dry eye. The visual effects of various display characteristics such as lighting, glare, display quality, refresh rates, and radiation are also discussed. Treatment requires a multidirectional approach combining ocular therapy with adjustment of the workstation. Proper lighting, anti-glare filters, ergonomic positioning of computer monitor and regular work breaks may help improve visual comfort. Lubricating eye drops and special computer glasses help relieve ocular surface-related symptoms. More work needs to be done to specifically define the processes that cause computer vision syndrome and to develop and improve effective treatments that successfully address these causes.     

A hyperventilation theory of job stress and musculoskeletal disorders

BACKGROUND: There is evidence of a link between job stress and upper extremity work-related musculoskeletal disorders. However, the biobehavioral mechanisms by which psychosocial stress factors contribute to the development of musculoskeletal disorders are uncertain. METHODS: Based on established principles of breathing and job stress and the relevant empirical literatures, a hyperventilation theory of job stress and work-related musculoskeletal disorders was developed. RESULTS: Hyperventilation (overbreathing) refers to a drop in arterial CO2 caused by ventilation that exceeds metabolic demands for O2. Excessive loss of CO2 (increase in rate of flow of CO2 from cells to longs) that results from hyperventilation produces a rise in blood pH (i.e., respiratory alkalosis). This disruption in the acid-base equilibrium triggers a chain of systemic physiological reactions that have adverse implications for musculoskeletal health, including increased muscle tension, muscle spasm, amplified response to catecholamines, and muscle ischemia and hypoxia. Hyperventilation is often characterized by a shift from a diaphragmatic to a thoracic breathing pattern, which imposes biomechanical stress on the neck/shoulder region due to the ancillary recruitment of sternocelidomastoid, scalene, and trapezius muscles in support of thoraci breathing. CONCLUSIONS: A hyperventilation theory provides an innovative framework for understanding how job stress contributes to pathophysiological processes that increase the risk of work-related musculoskeletal disorders. With respect to the control of these disorders, a hyperventilation theory has important implications for establishing effective work organization interventions and individual stress-management methods. In this regard, breathing is a biobehavioral metric for assessing whether psychosocial aspects of work organization are in balance with a worker's needs and resources. A hyperventilation theory also provides a unique rationale for coping with job stress and musculoskeletal discomfort through breathing training, light physical exercise, and rest breaks.     

Evaluation of symptom surveys for occupational musculoskeletal disorders

Symptom surveys have been used extensively as part of workplace ergonomic screening programs and epidemiologic assessments of musculoskeletal disorders in groups of workers. This paper examines the reliability and validity of two musculoskeletal symptom surveys, the Nordic Musculoskeletal Questionnaire (NMQ) and a survey used in conjunction with epidemiologic assessments by the National Institute for Occupational Safety and Health (NIOSH). Journal articles assessing the validity and reliability of the NMQ were reviewed. A retrospective assessment combining two NIOSH cohorts with a total of 852 workers assessed the reliability and validity of that survey. Reliability was assessed through test-retest methods and interitem correlations between similar questions. Validity was assessed by comparison with results from physical examination assessments of workers and self-reports of workers seeking medical care. Both reliability and validity were found to be acceptable for the purposes of workplace ergonomics programs. Implications for use of these surveys for prevention and treatment outcomes research are discussed. (This article is a US Government work and, as such, is in the public domain in the United States of America.) © 1996 Wiley-Liss, Inc.     

The correlation between ART and OCRA methods used for posture assessment of repetitive tasks

Background and Objective: Repetitive tasks are among the causes of musculoskeletal disorders. Assessment of repetitive tasks is performed through various methods with different scores and significance given to risk factors considered in these methods. Knowing the strengths and weaknesses of each method can contribute to modifying the methods and improving the correlation between them. This study aimed to investigate the correlation between ART and OCRA methods in a career with repetitive movements. Methods: After hierarchical task analysis in a vegetable grower job with repetitive movements, the subtasks were assessed by an assessor who mastered both ART and OCRA methods. The final score of each method was checked using the Pearson correlation coefficient in SPSS 18, after testing the normality of data. Results: Moderate risk levels were reported for 16 out of the 14 sub-tasks analyzed using both methods. In the ART method, 3 sub-tasks and in the OCRA method, 2 sub-tasks had high-risk levels. The Pearson correlation coefficient was 0.842 indicating a moderate correlation between the two posture assessment methods. Conclusion: The findings of the study showed an acceptable correlation and compatibility between the two methods considering the risk levels.     

The Impact of Carpal Tunnel Syndrome on Work Status: Implications of Job Characteristics for Staying on the Job

This prospective study tested the contribution of occupational factors to a multifactorial predictive model of work status among patients with carpal tunnel syndrome (CTS). The study recruited a community-wide sample of patients and included cases that were non-occupational as well as occupational in etiology. At baseline and follow-up 18 months later, trained interviewers administered a structured telephone questionnaire to 102 participants, that included items on demographics, medical history, psychosocial, and occupational factors. Multivariate logistic regression analyses indicated that patients presenting with CTS were more likely to continue working if they had modifications to their jobs, worked for employers with fewer than 250 employees, and held jobs not characterized by the frequent use of force. We also found that White (non-Hispanic) patients were more likely to continue working than those from other ethnic groups. Our findings also suggest that job strain may contribute to earlier changes in work status following diagnosis. The receipt of worker compensation was not found to be a significant predictor of work status. Workplace assessment and job modification appear to be important aspects of care for the worker presenting with CTS, regardless of whether the CTS is occupationally caused or not.     

Fear avoidance and chronic musculoskeletal pain

Confrontation and avoidance are the two extreme responses to the fear of pain. Life-events, personality, previous experience of and coping strategies for pain, together with iatrogenic factors and parental attitudes, comprise the psychosocial context in which fear of pain may persist. This leads to avoidance of anything which might conceivably provoke it. Pain avoidance, if unrecognized and untreated, may then become a pathological factor itself, independent of any concomitant organic changes and causing progressive stiffness, weakness and reinforcement of the invalid status.