Risk Of Carpal Tunnel Syndrome Research Articles

Off-road machine controls: investigating the risk of carpal tunnel syndrome

Occupationally induced hand and wrist repetitive strain injuries (RSI) such as carpal tunnel syndrome (CTS) are a growing problem in North America. The purpose of this investigation was to apply a modification of the wrist flexion/extension models of Armstrong and Chaffin (1978, 1979) to determine if joystick controller use in oV-road machines could contribute to the development of CTS. A construction equipment cab in the laboratory was instrumented to allow force, displacement and angle measurements from 10 operators while they completed an ˜ 30-min joystick motion protocol. The investigation revealed that both the external fingertip and predicted internal wrist forces resulting from the use of these joysticks were very low, indicating that the CTS risk associated with this factor was slight. However, the results also indicated that, particularly for the ‘forward’ and ‘left’ right side motions and for all left side motions, force was exerted by other portions of the fingers and hand, thereby under-predicting the tendon tension and internal wrist forces. Wrist angles observed were highest for motions that moved the joysticks to the sides rather than front to back. Thus, the ‘right’ and ‘left’ motions for both hands posed a higher risk for CTS development. When the right hand moved into the ‘right’ position and the left hand moved into the ‘left’ position, the wrist went into extension in both cases. Results indicate that neither learning nor fatigue aVected the results.

Gender differences in carpal tunnel syndrome? occupational and non-occupational risk factors in a population-based case-control study

PURPOSE: To determine the role of occupational and personal risk factors of carpal tunnel syndrome (CTS) separately in men and women.METHODS: Men (n = 404) and women (n = 404) younger than 65 years with first surgery for CTS in 1995/96 were sampled at random from the Bremen population (0.65 million) and matched to controls by age and gender sampled from the population registry. A self-administered questionnaire with 77 questions inquired about personal factors and activities during work and private environment (response: 60% of eligible cases and 52% in controls, respectively).RESULTS: CTS risk increased with body mass index (BMI): odds ratio for each unit of BMI [kg/m2] ORmen = 1.13; (95%-confidence-limits CLmen 1.06, 1.20), ORwomen = 1.09 (CLwomen 1.04, 1.14). Multivariate analysis adjusting for BMI showed more pronounced risks in men compared with women for repetitive movements of the hand: ORm = 2.89 (CL 1.82, 4.58); ORw = 2.10 (CL 1.37, 3.22), for forceful grip: ORm = 2.69 (CL 1.70, 4.27); ORw = 2.29 (CL 1.43, 3.66), but not for household chores: ORm = 0.64 (CL 0.40, 1.03); ORw = 0.88 (CL 0.34, 2.29). Women worked less hours per week than men but manual exposures remained more relevant in men after adjustment. Exposure-response-relationships could be demonstrated for all work related exposures. Women were at higher risk for CTS if they had had more than two births or a history of hysterectomy. Adding these factors to the logistic model still showed an association between manual work and CTS. Blinded expert rating (manual vs. non-manual) of jobs held by respondents and non-respondents and by cases and controls did not reveal relevant selection effects or recall-bias.CONCLUSIONS: CTS is a work related disease in both men and women, the fraction attributable to work in the Bremen population under age 65 is estimated to be 33% in men and 15% in women. Funding: German Federal Ministry for Education & Research: 01 EG 9512.

A fuzzy linguistic model for the prediction of carpal tunnel syndrome risks in an occupational environment

This research presents the development and evaluation of a fuzzy linguistic model designated to predict the risk of carpal tunnel syndrome (CTS) in an occupational setting. CTS has become one of the largest problems facing ergonomists and the medical community because it is developing in epidemic proportions within the occupational environment. In addition, practitioners are interested in identifying accurate methods for evaluating the risk of CTS in an occupational setting. It is hypothesized that many factors impact an individual's likelihood of developing CTS and the eventual development of CTS. This disparity in the occurrence of CTS for workers with similar backgrounds and work activities has confused researchers and has been a stumbling block in the development of a model for widespread use in evaluating the development of CTS. Thus this research is an attempt to develop a method that can be used to predict the likelihood of CTS risk in a variety of environments. The intent is that this model will be applied eventually in an occupational setting, thus model development was focused on a method that provided a usable interface and the desired system inputs can also be obtained without the benefit of a medical practitioner. The methodology involves knowledge acquisition to identify and categorize a holistic set of risk factors that include task-related, personal, and organizational categories. The determination of relative factor importance was accomplished using analytic hierarchy processing (AHP) analysis. Finally a mathematical representation of the CTS risk was accomplished by utilizing fuzzy set theory in order to quantify linguistic input parameters. An evaluation of the model including determination of sensitivity and specificity is conducted and the results of the model indicate that the results are fairly accurate and this method has the potential for widespread use. A significant aspect of this research is the comparison of this technique to other methods for assessing presence of CTS. The results of this evaluation technique are compared with more traditional methods for assessing the presence of CTS.

Male and Female Rate Differences in Carpal Tunnel Syndrome Injuries: Personal Attributes or Job Tasks?

Carpal tunnel syndrome (CTS) exacts a significant toll on the health and productivity of American workers. In 1996, 29,937 workers lost time from work due to CTS. Half of these were out for more than 25 days, compared to a median of 5 days for all injuries/illnesses. There are striking gender disparities in CTS rates. Overall, three times more women suffer from CTS than men. While some authors have emphasized the role of gender attributes in this risk disparity, the multifactoral causes of CTS, and the sex segregation of women into jobs with high-risk tasks, may be obscuring the work-related contributions to CTS risk. We argue here that men and women doing the same work tasks will have similar rates of CTS. To examine this premise, we used Bureau of Labor Statistics injury counts (numerator) and census data from the Current Population Survey (denominator) to determine injury rates of CTS for both men and women in six high-risk occupations: (1) assembler, (2) laborer—nonconstruction, (3) packaging and filling machine operators, (4) janitors and cleaners, (5) butchers and meat cutters, and (6) data entry keyers. Variable job tasks exist within five of the six high-risk occupational titles. Among those five, the male to female (M:F) risk rate ratio ranged from 0.29 to 0.50. However, the sixth occupational title, data entry keyers, which requires a single physical task, had a risk rate ratio of 1.06. This suggests that an equal risk between genders exists when the occupational tasks (exposure) are truly similar. Job task analysis unmasks potential biases that may wrongly attribute disproportionate CTS rates to gender attributes. This focus on gender attributes fails all workers because preventive interventions in the workplace are deferred. It fails women disproportionately because they are overrepresented in jobs at high risk for CTS.

Beating Injury with a Different Drumstick: A Pilot Study

Many studies indicate that percussionists are among the instrumentalists at higher risk for playing-related musculoskeletal disorders. Several drummers with musculoskeletal disorders have reported an alleviation of symptoms and a return to pain-free playing with the use of a newly developed oriented polymer drumstick. These anecdotal reports have prompted the authors to investigate the properties of the oriented drumsticks compared with wooden drumsticks. This paper reviews the musculoskeletal problems of percussionists as well as the risk factors for work-related musculoskeletal disorders, and presents the results of preliminary tests comparing the properties of the oriented polymer drumsticks with those of wooden drumsticks. Electronic devices for measuring vibration amplitude were attached to the drumsticks, which were mounted with a clamp on one end. The drumsticks were tapped gently and the response was recorded. There was a noticeable difference in amplitude between the two types of drumsticks: the oriented polymer drumsticks stopped vibrating sooner than the wooden drumsticks. Risk factors for work-related musculoskeletal disorders include high repetition, high force, and other factors, such as vibration. With regard to carpal tunnel syndrome risk, the vibration properties of oriented polymer drumsticks are potentially favorable compared with wooden drumsticks. The authors’ next step is to determine whether the oriented polymer drumsticks are associated with a reduction of risk for playing-related musculoskeletal disorders in drummers.

Wrist positions and movements as possible risk factors during machine milking

High prevalence of hand and wrist symptoms has been found in females working with machine milking. Therefore the aim of this study was to quantify the positions and movements of the wrist during machine milking, and to compare tethering and loose-housing systems with respect to this. Biaxial electrogoniometers and data loggers were used for recording flexion and deviation angles of both the right and left wrists in 11 healthy milkers. For each individual 25 min of representative work was recorded in each system. High values of dorsiflexion and radial deviation were found, which might induce an increased risk of carpal tunnel syndrome. Moreover, the velocity and repetitiveness were close to those values described in repetitive work with a high risk of elbow and hand disorders in the fish-processing industry and giro-form data entry work. According to our findings, the load on the upper extremities has increased with respect to dorsiflexed hand position and repetitiveness when milking in the modern loose-housing milking system. This is probably due to the change of the working position and/or the higher productivity (number of cows that milked per time unit) in the loose-housing system as compared to the old-fashioned tethering system. These negative effects on wrist positions and movements should be considered when building new milking systems.

Prevalence and incidence of carpal tunnel syndrome in a meat packing plant.

OBJECTIVES: To determine prevalence and incidence of carpal tunnel syndrome (CTS) in a modern meat packing plant. The secondary objective was to explore the relation between ethnicity and CTS. METHODS:...

Occupational illnesses within two national data sets.

To describe occupational illness data in two large data sets, two national data sets were aggregated, and the numbers, percentages, and rates of cases of occupational illnesses were determined. Job-related illness data were from Bureau of Labor Statistics documents containing Annual Survey and Census of Fatal Occupational Injury data. A severity index was created to assess the overall burden of a disease. The index multiplies the number of cases times the median days lost. Circulatory disease accounted for 85% of the deaths in the Census and at least 80% in the Annual Survey. More fatal myocardial infarctions occurred on Monday than on any other day. Low-paying occupations had the most myocardial infarctions: operators, laborers, and truck drivers; high-paying occupations had the least: executives, administrators, and managers. Carpal tunnel syndrome and hearing loss accounted for more morbidity, measured by cases and days lost, than any other illness. Persons at great risk for carpal tunnel syndrome included dental hygienists, butchers, sewing machine operators, and dentists. Mental disorders generated more morbidity than is generally acknowledged. Neurotic reactions to stress were highest in the transportation and public utility industries, as well as in finance, insurance, and real estate. Manufacturing contributed far more cases than any other industry. Industries generating significant asbestos-related deaths included construction and boat building. Ninety-three percent of all illness fatalities were among men. Few African Americans died from coal-workers' pneumoconiosis. Illness cases increased much faster than injury cases in recent years. The two data sets provide insights into the incidences and prevalences of occupational illnesses, but underestimate the burden of job-related illnesses.

Predictive models of carpal tunnel syndrome causation among VDT operators

Carpal tunnel syndrome (CTS), a cumulative trauma disorder of the hand and wrist, is one of the most common disabling injuries experienced by video-display terminal (VDT) operators. The purpose of this study was to develop a theoretically based operational quantitative predictive model of the risk of work-related CTS among VDT operators. A total of 100 female VDT operators, who performed a variety of office functions, were studied at a major midwestern university. Data were collected on job exposure, anthropometry and posture factors using questionnaires, direct observation and video-recording. Discriminant analysis and logistic regression were performed to develop the operational models. The results of the study indicated the following: (1) percentage of workday working with a VDT was the most significant factor and accounted for 60% of the variance explaining the causation of musculoskeletal discomforts associated with CTS; (2) discriminant function with six variables (i.e. work duration, trunk incline, wrist extension, wrist ulnar deviation, overall anthropometric measure, weighted anthropometric measure) correctly classified 73% of the CTS group and 72% of the non-CTS group; (3) using the logistic regression model, the probabilities associated with changes in the predictive variables as affecting CTS risk are presented such that increasing the daily work duration from 1 h to 4 h increases the probability of CTS risk from 0.45 to 0.92. The results of the study suggest that the main causation of CTS is job design, the secondary (and lesser cause) is posture associated with the workplace design and the least contributing factor to CTS causation is the individual's anthropometric make-up.

Risk factors for carpal tunnel syndrome in a general population.

OBJECTIVE: To determine the individual, physical, and psychosocial risk factors for carpal tunnel syndrome in a general population. METHODS: Population based case-control study in Marshfield epidemiological study area in Wisconsin,...

Switch from conventional to high-flux membrane reduces the risk of carpal tunnel syndrome and mortality of hemodialysis patients

The use of a high-flux membrane, which eliminates larger molecular weight solutes with better biocompatibility, has steadily increased since the discovery of beta-2 microglobulin (beta 2m) amyloidosis in 1985. The long-term effects of a dialyzer membrane on morbidity and mortality are not completely understood. To examine the membrane effect as a factor of carpal tunnel syndrome onset and mortality, multivariate Cox regression analysis with time-dependent covariate was conducted on 819 patients from March 1968 to November 1994 at a single center. Two hundred and forty-eight of the patients were either switched from the conventional to high-flux membrane or treated only with a high-flux membrane. Fifty-one patients underwent a CTS operation and 206 died. Membrane status (on high-flux or on conventional) was considered as time-dependent covariate and risk was adjusted for age, gender, type of renal disease and calendar year of dialysis initiation. The relative risk of CTS was reduced to 0.503 (P < 0.05) and mortality 0.613 (P < 0.05) by dialysis on the high-flux membrane, compared to the conventional membrane. Serial measurements of beta 2m indicated significantly lower beta 2m to persist in patients on the high-flux membrane. The high-flux membrane decreased the risk of morbidity and mortality substantially. Larger molecule elimination was shown important not only for preventing beta 2m amyloidosis, but for prolonging survival of dialysis patients as well.

A fuzzy linguistic model for the prediction of carpal tunnel syndrome risks in an occupational environment

This research presents the development and evaluation of a fuzzy linguistic model designated to predict the risk of carpal tunnel syndrome (CTS) in an occupational setting. CTS has become one of the largest problems facing ergonomists and the medical community because it is developing in epidemic proportions within the occupational environment. In addition, practitioners are interested in identifying accurate methods for evaluating the risk of CTS in an occupational setting. It is hypothesized that many factors impact an individual's likelihood of developing CTS and the eventual development of CTS. This disparity in the occurrence of CTS for workers with similar backgrounds and work activities has confused researchers and has been a stumbling block in the development of a model for widespread use in evaluating the development of CTS. Thus this research is an attempt to develop a method that can be used to predict the likelihood of CTS risk in a variety of environments. The intent is that this model will be applied eventually in an occupational setting, thus model development was focused on a method that provided a usable interface and the desired system inputs can also be obtained without the benefit of a medical practitioner. The methodology involves knowledge acquisition to identify and categorize a holistic set of risk factors that include task-related, personal, and organizational categories. The determination of relative factor importance was accomplished using analytic hierarchy processing (AHP) analysis. Finally a mathematical representation of the CTS risk was accomplished by utilizing fuzzy set theory in order to quantify linguistic input parameters. An evaluation of the model including determination of sensitivity and specificity is conducted and the results of the model indicate that the results are fairly accurate and this method has the potential for widespread use. A significant aspect of this research is the comparison of this technique to other methods for assessing presence of CTS. The results of this evaluation technique are compared with more traditional methods for assessing the presence of CTS.

Carpal tunnel syndrome: what is attributable to work? The Montreal study.

OBJECTIVE: To estimate the fraction of carpal tunnel syndrome (CTS) that is attributable to work in the total adult population of the island of Montreal. METHODS: The population consisted of...

Evidence for Work-Related Musculoskeletal Disorders

Evidence for Work-Related Musculoskeletal Disorders

Cumulative Trauma Disorders: Behavioral Injury Prevention at Work

The purpose of this study was to decrease the risk of carpal tunnel syndrome (CTS) during keyboard entry tasks through a combination of training, self-monitoring, feedback, goal-setting, and reinforcement. Technologies from biomechanics, ergonomics, and behavioral psychology were combined effectively to construct a powerful training package. As the subjects entered text on a keyboard, their postures and hand-wrist positions were recorded. After baseline data were gathered, subjects received training and self-monitored either posture or hand-wrist position. Feedback, goal-setting, and reinforcement were given later on both behaviors in a staggered fashion. The results indicate dramatic increases in the percentages of correctly performed postures and neutral hand-wrist positions, for all subjects. The training components used are reviewed in detail and the impact of these results is discussed.

Upper Extremity Disorders in a Pork Processing Plant: Relationships Between Job Risk Factors and Morbidity

Thirty-two jobs at a pork processing plant were semi-quantitatively analyzed in terms of their ergonomic characteristics, then classified as “hazardous” or “safe” in terms of potential risk for elbow or hand/wrist disorders. The spectrum, number, and incidence of such disorders occurring during the preceding 20 months were then compared to the job analyses and hazard classifications. There were 104 disorders associated with 15 job categories. The disorders included epicondylitis (24), nonspecific hand/wrist pain (41), carpal tunnel syndrome (CTS) (21), trigger finger (12), trigger thumb (3), and DeQuervain's tenosynovitis (3). The strength demands of the jobs associated with morbidity were significantly greater than those of jobs without morbidity. Differences in wrist posture were less significant. Type of grasp and repetitiveness were not significantly different. Practically all morbidity (96%) was associated with the hazardous job categories and occurred with a characteristic pattern of co-morbidity. The hazard classification scheme correctly predicted risk of upper extremity morbidity for 13 (87%) of the 15 job categories associated with morbidity and correctly predicted a lack of risk of morbidity for 16 (94%) of the 17 job categories not associated with morbidity. Significantly elevated relative risks were observed for any upper extremity disorder (11.4), any disorder excluding CTS (39.4), all specific disorders (6.9), and all specific disorders excluding CTS (19.4). The relative risk for CTS was 2.8 and not statistically significant. The results of this study provide additional epidemiological evidence that upper extremity musculotendinous disorders and some cases of CTS may be causally associated with work. The exertional demands of a task best explained the occurrence of morbidity.

Upper Extremity Disorders in a Pork Processing Plant: Relationships Between Job Risk Factors and Morbidity

Thirty-two jobs at a pork processing plant were semi-quantitatively analyzed in terms of their ergonomic characteristics, then classified as "hazardous" or "safe" in terms of potential risk for elbow or hand/wrist disorders. The spectrum, number, and incidence of such disorders occurring during the preceding 20 months were then compared to the job analyses and hazard classifications. There were 104 disorders associated with 15 job categories. The disorders included epicondylitis (24), nonspecific hand/wrist pain (41), carpal tunnel syndrome (CTS) (21), trigger finger (12), trigger thumb (3), and De-Quervain's tenosynovitis (3). The strength demands of the jobs associated with morbidity were significantly greater than those of jobs without morbidity. Differences in wrist posture were less significant. Type of grasp and repetitiveness were not significantly different. Practically all morbidity (96%) was associated with the hazardous job categories and occurred with a characteristic pattern of co-morbidity. The hazard classification scheme correctly predicted risk of upper extremity morbidity for 13 (87%) of the 15 job categories associated with morbidity and correctly predicted a lack of risk of morbidity for 16 (94%) of the 17 job categories not associated with morbidity. Significantly elevated relative risks were observed for any upper extremity disorder (11.4), any disorder excluding CTS (39.4), all specific disorders (6.9), and all specific disorders excluding CTS (19.4). The relative risk for CTS was 2.8 and not statistically significant. The results of this study provide additional epidemiological evidence that upper extremity musculotendinous disorders and some cases of CTS may be causally associated with work. The exertional demands of a task best explained the occurrence of morbidity.

Issue &amp; Opinions: Receiver operating characterist curve anic analysis in the prediction of carpal tunnel syndrome: A model for reporting Electrophysiological data

Receiver operating characteristic (ROC) curves were used to predict the risk of carpal tunnel syndrome (CTS). Patients were classified clinically as: (1) normal exam and no symptoms (169 hands); (2) having a motor and/or sensory deficit typical of CTS (115 hands); (3) having a history characteristic of CTS (156 hands); and (4) nondiagnostic symptomatology (122 hands). Electrophysiological studies consisted of median and ulnar motor, sensory, and palmar measurements. Group mean values for group 1 differed significantly from groups 2 and 3 (not 4) for all measurements, but values overlapped considerably. Median distal motor latency (DMML) combined with median-ulnar palmar latency differences (MUPLD) had significantly superior discriminant power than other measurements and correlated highly for all groups (r values = 0.71-0.73). These variables were used to construct ROC curves and prediction tables. The approach used allows one to assign a percentage risk of having a CTS and can be used in outcome studies.

CARPAL TUNNEL SYNDROME AND ITS RELATION TO GENERAL PHYSICAL CONDITION

Risk for carpal tunnel syndrome is closely related to general physical condition. Our findings confirm that healthy people are less likely to develop median nerve conduction abnormalities at the carpal tunnel than are unhealthy people. Being overweight, older, and physically inactive are major risk factors for slowing and clinical CTS. Workers' compensation patients with CTS, as a group, are identifiable by being overweight and physically inactive. Individual factors, such as body mass index, age, wrist dimensions, and physical activity, are far more important for determining who develops clinical CTS than are job-related factors, such as specific job, force or repetitions, duration of employment, or industry.

Aerodynamic Handlebars-Reply

In Reply. —The letter by Dr Jacques adds to the minuscule literature on aerodynamic handlebars. It is reassuring that the riders who were observed using these handlebars were adults and uniformly wore helmets. Overuse injuries from the hyperextended neck position have been reported. 1 However, the forearm rests and resultant neutral wrist position might lessen the risk of carpal tunnel syndrome (Eric S. Smith, MD, written communication, July 1991), a common malady of endurance cyclists. In suggesting more research on aerobars, I did not want to lessen the important research focus on head injury prevention by helmets. As Jacques points out, the majority of bicyclists would benefit from data already available showing that helmets reduce head injury. 2 Trauma might be avoided by a mandatory helmet law. 3 Cycling is increasing in popularity among adult fitness enthusiasts. With this trend and the arrival of another cycling season, physicians can expect