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Biomedical subjects

T J Armstrong

Publications and source records attributed to T J Armstrong.

At least 55 records · Page 3Linked to original sources
PubMed1988

Can in-plant exercise control musculoskeletal symptoms?

After 1 year of an on-job exercise program to control musculoskeletal symptoms in the neck and upper limb, there were no statistically significant differences in localized postural discomfort scores or in the proportion of those whose discomfort decreased based on exercise participation. Although no clear reduction in discomfort was achieved by the exercise program alone, at least 67% of respondents who participated in the exercise program reported that the program made them feel better.

Adult↗
PubMed1987

Occupational factors and carpal tunnel syndrome.

Carpal tunnel syndrome (CTS) is the most commonly reported nerve entrapment syndrome. The prevalence of CTS among 652 active workers in jobs with specific hand force and repetitiveness characteristics was estimated. The prevalence of CTS ranged from 0.6% among workers in low force-low repetitive jobs to 5.6% among workers in high force-high repetitive jobs. When controlling for potential confounders, the odds ratio for the high force-high repetitive jobs was more than 15 (p less than .001) compared to the low force-low repetitive jobs. High repetitiveness appears to be a greater risk factor than high force (odds ratio of 5.5 p less than .05 versus 2.9 and not statistically significant).

Adult↗
PubMed1987

Analysis of cumulative strain in tendons and tendon sheaths.

Twenty-five fresh frozen flexor digitorum profundus tendons stratified by sex were subjected to uniaxial step stress and cyclic loads in twelve intact human cadaver hands. By attaching specially designed clip strain gage transducers on tendons just proximal and distal to an undisrupted carpal tunnel, the interactions of the tendons, tendon sheath and retinacula were measured. The elastic and viscous response of the tendon composites to step stresses were found to fit fractional power functions of stress and time respectively. A significant and quantifiable decrease in strain from the proximal to the distal tendon segment was found to be a function of wrist deviation. The results indicate that an accumulation of strain does occur in tendinous tissues during physiologic loading.

Aged↗
PubMed1987

Ergonomics considerations in hand and wrist tendinitis.

The objectives of this article are to present (1) a historical perspective on hand and wrist tendinitis in workers, (2) new data that demonstrate a relationship between the repetitiveness and forcefulness of manual work and the prevalence of tendinitis, (3) possible biomechanical factors in tendinitis, and (4) possible job modifications for the prevention of tendinitis. Numerous studies during the last 100 years show that tendinitis is a major cause of worker suffering and workers' compensation in intensive hand work. Epidemiologic data show that the risk of hand and wrist tendinitis in persons who perform highly repetitive and forceful jobs is 29 times greater than in persons who perform jobs that are low in repetitiveness and force. A possible factor in this relationship is viscous deformation of the tendons and adjacent tissues. Although these data suggest that the risk of tendinitis among workers can be reduced by reduction of the repetitiveness and the forcefulness of the work, this hypothesis has not yet been fully tested.

Ergonomics↗
PubMed1987

Ergonomics and the effects of vibration in hand-intensive work.

Along with ergonomic factors, such as forceful and repeated exertion and certain postures, vibration has been cited as a factor of chronic nerve and tendon disorders such as carpal tunnel syndrome and tendinitis. The arguments for the contribution of vibration come from epidemiologic studies, clinical case analyses, and studies of short-term effects. It is well established that vibration stimulates muscle contraction, which is called the tonic vibration reflex. It is also known that vibration reduces tactility and that tactility affects the amount of force exerted to hold or manipulate a given object. For localized vibration exposure of the hand and arm to occur, the hand must grip a vibrating object. Vibration may increase the risk of chronic tendon and nerve disorders by increasing the force exerted in repetitive manual tasks. This close relationship between force and vibration, and difficulties in measuring force and vibration in manual work, makes it very difficult to determine their relative contributions in epidemiologic and clinical studies.

Carpal Tunnel Syndrome↗
PubMed1986

Detection of cumulative trauma disorders of upper extremities in the workplace.

Surveillance for musculoskeletal disorders of the upper extremity in industry is in its infancy. Research efforts to elucidate the causal factors of these disorders often rely on either the analysis of existing medical records, worker compensation records (passive surveillance), or the surveying of workers with questionnaire and physical examination (active surveillance). The use of either type of data for routine surveillance presents several difficulties illustrated with the results presented in this paper. The analysis of existing records is generally less costly but the reliability of the data is difficult to assess. Standardized questionnaire and physical examinations can be as sensitive as the use of unusually thorough existing occupational medical records; however, it is unclear whether the additional cost of an active surveillance system will deter the routine use of such systems.

Arm↗
PubMed1986

Hand wrist cumulative trauma disorders in industry.

A total of 574 active workers from six different industrial sites were categorised into four force repetitive exposure groups. Workers in low force-low repetitive jobs served as an internal comparison population for the three other groups. Videotapes and surface electromyography were used to estimate hand force and repetitiveness. The presence of cumulative trauma disorders (CTD) was determined by structured interview and standardised non-invasive physical examination. Only workers who had been working on the study jobs for at least one year at the time of evaluation were eligible for selection. Categorisation of jobs and identification of CTDs were carried out independently by investigators who were appropriately blinded to exposure and outcome. The analysis of associations between CTDs and exposure categories were performed using Mantel-Haenszel plant adjusted odds ratios and unconditional multiple logistic regression. Significant positive associations were observed between hand wrist CTDs and high force-high repetitive jobs. These associations were independent of age, sex, years on the specific job, and plant.

Adult↗
PubMed1986

Ergonomics and cumulative trauma disorders.

Chronic tendon and nerve disorders of the upper extremity, such as tendinitis and carpal tunnel syndrome, are a common problem among persons who routinely perform hand-intensive work. This article summarizes the most commonly reported occupational risk factors: repetitiveness, forcefulness, certain postures, mechanical stresses, exposure to vibration, and exposure to low temperatures. It describes how to look for these factors and how to control them through the design of work equipment and procedures.

Arm Injuries↗
PubMed1985

Mechanical considerations of skin in work.

Skin forms a link through which the forces required to hold and manipulate objects are transmitted from the musculoskeletal system to the objects; while these forces are necessary for most work, excessive forces can be injurious. This paper discusses some of the mechanical properties of skin and discusses how they are important in manual work. Recommendations for the design of hand-held objects and for future research are given.

Biomechanical Phenomena↗
PubMed1985

Assessment of hand vibration exposure on an assembly line.

This paper describes a study undertaken to evaluate and control vibration exposure associated with pneumatic screwdrivers used in an electrical appliance assembly plant. The study was motivated by management's concern about reports of cumulative trauma disorders in the upper extremities of workers who used pneumatic screwdrivers. Vibration exposure from power hand tools on an assembly line is difficult to predict due to highly variable conditions and techniques used between operators. Vibration exposure was measured using observation samples of tool vibration obtained on the assembly line for individual assembly tasks. Typical tool one-third octave band acceleration spectra estimated from laboratory measurements were used in conjunction with the measured exposure times to compare workers' risk of exposure to the hazards associated with operating vibrating hand tools. Characteristic vibration produced by the tools during phases of operation were separated and analyzed individually to identify and control the source.

Hand↗
PubMed1985

A program for control of repetitive trauma disorders associated with hand tool operations in a telecommunications manufacturing facility.

This paper summarizes efforts to control the incidence and severity of repetitive trauma disorders associated with hand tool operations in a telecommunications manufacturing facility with 6,600 employees. Repetitive trauma disorders--including strains, tendinitis, ganglions and carpal tunnel syndrome--were the leading cause of lost time and workers' compensation expenses at this plant in 1979. The plant-wide incidence rate of OSHA reportable repetitive trauma disorders was 2.2 cases per 200,000 workhours and resulted in 1,001 lost workdays. Incidence rates as high as 4.6 were reported in some areas, but were believed to be much higher among persons who actually perform repetitive work in these areas. In the spring of 1981, the plant safety and health committee undertook a control program that included creation of a task force, a training program, improvements in the design of workstations and tooling, and management of restricted workers. During 1982, the incidence rate of repetitive motion disorders has decreased to .53 cases per 200,000 workhours and resulted in only 129 lost workdays.

Equipment Safety↗
PubMed1984

Some histological changes in carpal tunnel contents and their biomechanical implications.

The purpose of this study was to investigate the pathological influence of mechanical stresses that occur inside the carpal tunnel during exertions of the hand. Microscopic changes in fibrous tissue density, in synovial, subsynovial, and adjacent connective tissue density, and in median nerve epineurium density, arteriole wall muscle thickness, and arterial and venule endoproliferation were investigated at 5-mm increments along a 9-cm range of six postmortem wrist specimens. All of these changes increased from normal in the proximal portions of the wrist, -30 to -40 mm from the wrist crease, to maximal values 0- to 20-mm distal to the wrist crease. The changes then decreased toward normal in the distal sections, 20 to 40 mm. The location and character of these changes suggest that repeated exertions with a flexed or extended wrist are an important factor in their etiology. The consistency with which they are found in this and other studies suggests that extreme changes associated with highly repetitive work or additional stress factors are required to produce symptoms in most cases of carpal tunnel syndrome.

Aged↗
PubMed1982

Investigation of cumulative trauma disorders in a poultry processing plant.

Cumulative trauma disorders such as carpal tunnel syndrome and tenosynovitis can be caused, precipitated, or aggravated by repeated exertions with the hand. This paper describes a study in a poultry processing factory that proceeds from an analysis of health records to an analysis of work methods, postures and forces. Alternative work procedures and knife designs are recommended to reduce stressful work postures and forces.

Animals↗
PubMed1982

Health effect of occupational exposure to steady magnetic fields.

An observational cross sectional study was conducted to determine if long term exposure to steady magnetic fields of up to 200 Oersteds could be related, on a dose-response basis, to findings of medical examinations. Health data were obtained for 320 workers who spent a major portion of their workday in the magnetic fields produced by the direct current through large electrolytic cells. These data were compared to those for a control group of 186 workers. The vertical and horizontal components of the magnetic fields were measured in each cell room and the time weighted average exposure to magnetic fields was calculated for each job classification. The leukocyte count and the monocyte percent were found to decrease, while the lymphocyte percent was found to increase with increased exposure to the horizontal component of the magnetic field. A slight tendency of both the systolic and diastolic blood pressures to increase with increasing exposure to the vertical component of the magnetic field was found in the black workers in the study. No such effect was found in the other racial groups. No other signs or symptoms were found to depend on magnetic field exposure.

Analysis of Variance↗