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Biomedical subjects

W M Keyserling

Publications and source records attributed to W M Keyserling.

At least 19 recordsLinked to original sources
PubMed1997

Work-related musculoskeletal disorders: comparison of data sources for surveillance.

Work-related upper extremity musculoskeletal disorders "associated with repeated trauma" account for more than 60% of all newly reported occupational illness, 332,000 in 1994 according to the U.S. Department of Labor. These numbers do not include, for example, those disorders categorized as "injuries due to overexertion in lifting," approximately 370,000. Early identification of potential disorders and associated risk factors is needed to reduce these disorders. There are a number of possible methods for conducting surveillance for work-related musculoskeletal disorders (WMDs) based on health outcome: workers' compensation, sickness and accident insurance, OSHA 200 logs, plant medical records, self-administered questionnaires, professional interviews, and physical examinations. In addition, hazard surveillance based on evaluation of job exposures to physical stressors by nonoccupational health personnel is possible. As part of a large labor-management-initiated intervention study to reduce the incidence of WMDs in four automotive plants, we were able to compare the strengths and limitations of each of these surveillance tools. University administered health interviews yielded the highest rate of symptoms; combined physical examinations plus interview (point prevalence) rates were similar to self-administered questionnaires (period prevalence) rates. Plant medical records yielded the lowest rate of WMDs. WMD status on self-administered questionnaire and on physical examination were associated with risk factor exposure scores. This study suggests that symptoms questionnaires and checklist-based hazard surveillance are feasible within the context of joint labor-management ergonomics programs and are more sensitive indicators of ergonomic problems than pre-existing data sources.

Cumulative Trauma Disorders↗
PubMed1995

The effect of size and fabric weight of protective coveralls on range of gross body motions.

This study evaluated the effects of garment size and fabric weight on range-of-motion (ROM). Ten male subjects performed a series of twelve gross body movements while wearing each of nine similarly styled coveralls. The coveralls were undersized, appropriately sized, and oversized, and were constructed from three different weights of poly/cotton fabric. A balanced 3 x 3 repeated measures experimental design was used, along with a seminude control condition. ROM was measured with a two-arm manual goniometer. Garment size significantly affected (p < .05) ROM for all movements except shoulder extension and trunk lateral flexion. Compared to seminude ROM, undersized garments reduced the mean ROM by as much as 24% in the case of hip flexion. Fabric weights on ROM were significant for shoulder extension and elbow, hip, knee, and shoulder horizontal flexion. Fabric weight affected ROM less than garment size. Interaction effects between fabric weight and size generally were not significant. These results demonstrate that undersized garments can measurably reduce the wearer's movement capability. Providers of protective clothing should ensure that garments are not undersized and should consider the benefits of oversizing against possible safety and wearer acceptance problems.

Adult↗
PubMed1993

Median sensory distal amplitude and latency: comparisons between nonexposed managerial/professional employees and industrial workers.

To test for associations between occupation and median nerve dysfunction, measures of median motor and median and ulnar sensory amplitude and distal latency were compared among three populations: control subjects without occupational exposure to highly forceful or repetitive hand exertions (N = 105), industrial workers with hand/wrist symptoms (N = 103), and asymptomatic industrial workers (N = 137). Mean sensory amplitudes were significantly smaller (p < 0.05) and motor and sensory distal latencies were significantly longer (p < 0.001) in the industrial "asymptomatic hand" population compared to the control population. Prolongation of median relative to ulnar latency was significantly longer in the asymptomatic industrial population (p < 0.05). Results were most plausibly explained by differences in checklist identified ergonomic stressors. Median sensory amplitudes were significantly smaller (p < 0.01) and latencies longer (p < 0.05) for industrial workers with exposure to high grip forces compared to those without. Exposure misclassification may have reduced power to detect statistically significant differences between exposed and nonexposed population groups.

Adult↗
PubMed1993

A checklist for evaluating ergonomic risk factors associated with upper extremity cumulative trauma disorders.

A two-page checklist for determining the presence of ergonomic risk factors associated with the development of upper extremity cumulative trauma disorders (e.g., repetitiveness, local mechanical contact stresses, forceful manual exertions, awkward postures, and hand tool usage) was developed and evaluated as part of a joint labour-management ergonomics intervention programme. This checklist was used by plant personnel at four work sites to assess the presence of upper extremity risk factors in 335 manufacturing and warehouse jobs. In addition, results generated by the checklist were compared to the results of ergonomic analyses performed by persons with advanced training (Masters degree) in occupational ergonomics for a subset of 51 jobs. Most of the jobs included in the survey were found to have significant exposures to upper extremity risk factors. Awkward work postures were common, with 90% of the jobs requiring wrist deviations outside the neutral range-of-motion. The jobs were also highly repetitive and frequently required workers to exert high hand forces. Results generated by the checklist were generally in agreement with results generated by the ergonomic analysts; however, the checklist was found to be more sensitive in identifying the presence of risk factors. The checklist was found to be an effective rapid-screening instrument for identifying jobs that expose workers to potentially harmful ergonomic stresses. However, the checklist methodology did not include sufficient documentation of work methods to identify specific job attributes associated with these exposures.

Arm Injuries↗
PubMed1993

Perceived exertion and discomfort associated with driving screws at various work locations and at different work frequencies.

Eighteen subjects drove screws with air-powered tools into perforated sheet metal at three vertical and two horizontal work locations using three different work paces (8, 10, and 12 screws/min). Subjects drove screws with a pistol-shaped tool on the vertical orientation at knee, elbow, and shoulder height. They used an in-line tool to drive screws on the horizontal surface. A horizontal beam was placed just below each subject's elbow height and they drove screws into it with the lower arm perpendicular to the torso and with the arms fully extended. Subjects drove screws for 10 min at each work location and frequency combination before they assessed the condition using the Borg ten-point ratio rating scale. Subjects also ranked seven body areas according to discomfort for each work location. A two-factor ANOVA (and comparable non-parametric statistics) showed that both work location and frequency were significant factors in determining the Borg ratings. As work pace increased, so did the Borg ratings of perceived exertion for each work location. For each incremental increase in work pace, the Borg ratings of perceived exertion increased 12% to 25%, depending on the work location. Driving screws at elbow height on the vertical surface and with the lower arm close to the body on the horizontal surface were the work locations with the smallest ratings of perceived exertion. The ratings of perceived exertion for driving screws at elbow height on the vertical surface were 18% to 50% lower than the ratings for driving screws at knee or shoulder height and the ratings of perceived exertion for driving screws with the lower arm close to the body on the horizontal surface were 21% to 24% lower than driving screws with the arms fully extended. No significant difference was found among the discomfort ranks given to the various body parts for the two horizontal work locations. Differences were found among the body part discomfort rankings for the vertical work locations. While driving screws at knee height, the torso was most stressed; the wrist and hand were most stressed while driving screws at elbow height, and the shoulder and upper arm were the body parts that were stressed the most while driving screws at shoulder height.

Adult↗
PubMed1991

Back disorders and nonneutral trunk postures of automobile assembly workers.

A case-referent study was conducted in an automobile assembly plant to evaluate the health effect of trunk postures, such as bending and twisting, that deviate from anatomically neutral. Cases of back disorders were all those of workers who reported back pain to the medical department in a ten-month period and met the severity criteria of an interview. The referents were randomly selected workers free of back pain according to medical department records, an interview, and an examination. For each of the final 95 cases and 124 referents, the job was analyzed for postural and lifting requirements with a video recording and software analysis system by analysts blinded to the case/referent status. Back disorders were associated with mild trunk flexion [odds ratio (OR) 4.9, 95% confidence interval (95% CI) 1.4-17.4], severe trunk flexion (OR 5.7, 95% CI 1.6-20.4), and trunk twist or lateral bend (OR 5.9, 95% CI 1.6-21.4). The risk increased with exposure to multiple postures and increasing duration of exposure.

Adult↗
PubMed1990

A three-dimensional ultrasonic system for posture measurement.

A time-efficient, cost-effective, and accurate system has been developed for measuring static three-dimensional joint coordinates in the laboratory. This system uses a personal computer interface to determine the distance between transmitters positioned at body joints and receivers positioned near the subject by measuring the travel time of ultrasound. Distance data are then converted to spatial coordinates and joint angles. The system can determine the location of 14 joints at one time. An experiment using three distances and five orientations between a transmitter and a receiver was performed to investigate the significance of measurement errors for the new system. The results showed that the standard deviation of the distance measurement was about 0.2 cm for single orientation conditions and was about 1 cm for all conditions tested. A second experiment using 11 transmitters and four receivers was performed to investigate the significance of measurement errors when determining three-dimensional coordinates. The results showed no significant difference between actual and measured coordinates. The system was then used to study the posture of a subject's upper extremity. Eight postures representing a variety of typical reaching tasks were examined. The results showed that the system was suitable for three-dimensional posture measurement.

Ergonomics↗
PubMed1989

Analysis of manual lifting tasks: a qualitative alternative to the NIOSH work practices guide.

A new method for evaluating ergonomic stresses on lifting tasks has been developed. This method utilizes the general procedures and hazard classification categories described in the National Institute for Occupational Safety and Health's (NIOSH) Work Practices Guide for Manual Lifting. The quantitative measurements of workplace dimensions and computations used by the NIOSH method to classify a job as "acceptable," "administrative controls required," or "hazardous" have been eliminated in favor of a table look-up procedure. A computer simulation was performed to compare results generated by the new method to results generated by the NIOSH method. The results of this simulation found that the new method was unbiased and was reasonably precise for most lifting activities.

Back Injuries↗
PubMed1987

Risk assessment in electronic assembly workers: carpal tunnel syndrome.

Symptoms that develop in workers after repeated mechanical injury may be overlooked until the disability affects their productivity and safety. Modifications in the design of hand-operated tools or adaptations in production ergonomics may prevent further damage and permit affected workers to recover while avoiding the development of repetitive cumulative trauma in workers who are new to the job task. This article describes the results of an on-site survey, a biomechanical analysis, and a special neurologic assessment in an electronic assembly plant and provides a structured approach to worker surveillance and intervention to reduce the risk of carpal tunnel syndrome caused by repetitive motions.

Biomechanical Phenomena↗
PubMed1986

A computer-aided system to evaluate postural stress in the workplace.

Stress caused by awkward working posture of the trunk and shoulders can result in fatigue, musculoskeletal disorders and nerve entrapment syndromes. To aid in evaluating the relationship between work activities and postural stress, a computer-aided system was developed. This system produces a detailed description of work tasks and a continuous record of trunk and shoulder activity on the same time scale. The system was used to evaluate postural stresses on a case study job in an automobile assembly plant. The results of the postural analysis were used to identify specific causes of postural stress and to develop recommendations for changes in work station equipment and methods to reduce stress.

Diagnosis, Computer-Assisted↗
PubMed1986

Occupational ergonomics--methods to evaluate physical stress on the job.

Ergonomics is the study of people at work to understand the complex relationships among people, machines, job demands, and work methods. All work, regardless of its nature, results in stress. As long as stress is kept within reasonable limits, work performance will be satisfactory and the worker's health and well-being will be maintained. However, if stress is excessive, undesirable outcomes may result in the form of accidents and injuries. A variety of musculoskeletal injuries and disorders can be caused by physical stress in the work environment. Because of the high medical and compensation costs associated with these problems, it becomes essential in many manufacturing situations to implement programs for controlling physical stress. An important part of any control program is job evaluation. We have presented several analytical methods for measuring and evaluating physical stress in the workplace. In almost all instances in which it is found to be excessive, stress can be reduced to acceptable levels by applying ergonomic principles to the design of facilities, processes, equipment, tools, and work methods. This design effort should be multidisciplinary, with inputs from medical personnel, engineers, ergonomists, and workers.

Accidents, Occupational↗
PubMed1985

Soft tissue disorders in the upper limbs of female garment workers.

In this cross-sectional investigation of female garment workers the prevalence of soft tissue disorders of the hands and arms was studied. The findings were compared with the prevalence of disorders in a group of female hospital employees not required to use repetitive hand motion. One hundred and eighty-eight garment workers and 76 hospital employees were surveyed by questionnaire and physical examination. The prevalences of persistent shoulder, wrist, and hand pain were significantly greater among the garment workers (rate ratio 2, 4, and 3, respectively). In both groups about 60% of the persistent hand pain was consistent with carpal tunnel syndrome (rate ratio 3). These associations held when the comparisons were stratified by age and by length of employment. Workers whose native language was not English were significantly less likely to report symptoms (rate ratio 0.6). Workers in hand sewing and trimming suffered especially high prevalences of persistent pain in all upper limb sites. Stitchers had elevated rates of pain in the shoulders, wrists, and hands. Workers ironing by hand had a significant elevation in elbow pain rates. Garment assembly tasks appear to be associated with cumulative trauma of the hands and wrists; the biomechanical features of these jobs should be studied in greater detail.

Adult↗
PubMed1980

Establishing an industrial strength testing program.

This study was performed to develop and evaluate a scheme for matching the strength of workers to the strength demands of their jobs. Biomechanical analyses were performed on production jobs in an aluminum reduction plant to identify and quantify strength demands. These data were used to design a set of nine strength tests which simulated job activities with the greatest strength requirements. A cross section of plant employees assigned to these jobs was strength tested and monitored for medical incidents for a period of over two years. Significant relationships were found among job strength requirements, worker strengths, and medical incidents. Workers with strength abilities (as determined by the tests) less than job strength requirements suffered a higher rate of medical incidents than workers whose strength abilities matched or exceeded job demands. It was concluded that strength testing can be used to identify workers who would be at increased risk of suffering medical incidents if placed on jobs which exceeded their strength abilities.

Adolescent↗
PubMed1980

Isometric strength testing as a means of controlling medical incidents on strenuous jobs.

This investigation was performed to determine if isometric strength tests can be used to select workers for strenuous jobs and to reduce occupational injuries which are caused by a mismatch between worker strength and job strength requirements. Twenty jobs in a tire and rubber plant were studied biomechanically to identify critical strength-demanding tasks. Four strength tests were designed to simulate these tasks, and performance criteria were established for passing the tests. New applicants were administered the tests during their preplacement examinations to determine if they possessed sufficient strength to qualify for the jobs. The medical incidence rate of employees who were selected using the strength tests was approximately one-third that of employees selected using traditional medical criteria. It was concluded that isometric strength tests can be used to reduce occupational injuries and should be considered for implementation in industries with strenuous jobs.

Accidents, Occupational↗