Classical syndromes in occupational medicine. Peripheral nerve entrapment syndromes and ergonomic factors

Pinch force sense test-retest reliability evaluation using contralateral force matching task

A high test-retest reliability in measurement of pinch force sense is required to assess a clinical parameter accurately over a longitudinal study. Ipsilateral reproduction (IR) task and contralateral matching (CM) task have commonly been used for the assessment of force sense. To date, there has been little research on the test-retest reliability of pinch force sense utilizing the contralateral force matching task. This research aimed to explore this phenomenon across a spectrum of reference force levels (10, 30, and 50 percent maximum voluntary isometric contraction (MVIC)) using a contralateral matching task. Every participant in the study was tested twice by the same skilled experts, with each session separated by one week. Although normalized variable error indicated a poor level of reliability (intraclass correlation coefficient (ICC) = - 0.25 to 0.05) for these force sense tests, normalized constant error (ICC = 0.76-0.85) and normalized absolute error (ICC = 0.61-0.81) results indicated a fair to good of reliability. The lower bound of 95% CI of ICC for NAE and NCE indicated fair test-retest reliability (0.41-0.69). These findings suggest that investigators can reasonably obtain a fair to good test-retest reliability when investigating pinch force sense using the contralateral matching task. The Bland-Altman plots, SEM, and MDD95% were lower at these lower reference force level (10% MVIC) compared to the level of higher reference forces (30% and 50% MVIC). Therefore, when the reference force level increases, the participant needs a larger NAE or NCE decrease to show that their pinch force sense has indeed improved.

Evaluation of the socioprofessional consequences of thoracic outlet syndrome

PURPOSE

Thoracic outlet syndrome (TOS) is a ductal syndrome that can have a significant functional impact. Various studies have highlighted positional factors and repetitive movements as risk factors for the development of TOS. However, there are few literature data on the socioprofessional consequences of TOS.

METHODS

We performed a prospective, cross-sectional, descriptive, multicentre study of workers having received a Doppler ultrasound diagnosis of TOS between December 17th, 2018, and March 16th, 2021. Immediately after their diagnosis, patients completed a self-questionnaire on the impact of TOS on their work activities. We assessed the frequency of TOS-related difficulties at work and the associated socioprofessional consequences. Trial Registration Number (TRN) is NCT03780647 and date of registration December 18, 2018.

RESULTS

Eighty-two participants (95.3%) reported difficulties at work. Seventy-seven of the participants with difficulties (94%) worked in the tertiary sector; these difficulties were due to prolonged maintenance of a posture, carrying loads, and repetitive movements. Although the majority of participants experienced organizational problems and lacked support at work, few of them had approached support organizations, expert and/or healthcare professionals.

CONCLUSIONS

TOS was almost always associated with difficulties at work (95.3%). However, poor awareness of sources of help or a perceived lack of need may discourage people with TOS from taking steps to resolve these difficulties. It is clear that the socioprofessional management of TOS requires significant improvements.

Effect of pinch types on pinch force sense in healthy adults

Pinch force sense plays an important role in the performance of daily finger movements, including tip, key, palmar pinch. The present study investigated the roles of pinch type in the sensation of pinch force among healthy participants in the ipsilateral force reproduction trial. This study instructed forty healthy adult subjects (20 women and 20 men) in producing reference forces at different levels [10, 30, 50% maximal voluntary isometric contraction (MVIC)] by adopting 3 pinch types (tip, key, and palmar pinches) and in reproducing the above force levels with the identical hand. Our study revealed that subjects are significantly more sensitive detecting alterations of pinching forces with tip pinch but not key or palmar pinch under high forces (30 and 50% MVIC) but not at lower force levels (10% MVIC).

Cumulative Trauma Disorders

Data from individual studies and worksites indicate that CTDs are a major problem in some industries. Evidence exists for an association between symptoms of CTDs and occupational risk factors such as forceful exertion, repetitiveness, and extreme postures. Although the pathogenesis of these disorders is not known, they are believed to involve physiological and mechanical responses of soft tissues to repeated or sustained biomechanical stress.

The efficacy of ergonomic interventions or programs must be evaluated using the same methods as used to identify problems initially. User (worker) feedback about any job or tool redesigns is essential.

Implementing ergonomic interventions likely will be an ongoing, iterative process. The ability of the occupational health nurse to carry out basic nursing functions of health promotion and prevention of injury and illness will be enhanced through the application of the ergonomic principles.

Effect of Force Level and Gender on Pinch Force Perception in Healthy Adults

This study investigated the effects of both force level and gender on pinch force reproduction errors in normal participants during an ipsilateral force reproduction task. In total, 20 healthy participants were asked to generate a range of levels of reference forces ranging from 5% to 60% maximal voluntary isometric contraction (MVIC) in increments of 5% MVIC using the tip pinch and to reproduce these forces using the same hand. The results showed that the males more accurately and consistently reproduced the forces than did the females, and the most accurate estimation occurred at approximately 20% to 35% MVIC. This finding can help us better understand the reasons for the higher rate of musculoskeletal disorders in females than in males and to develop tools and preventive strategies to decrease the rate of hand injuries in both genders.

Test-retest reliability of tip, key, and palmar pinch force sense in healthy adults

Background

No previous studies have investigated the test–retest reliability of tip, key, and palmar pinch force sense in healthy adults. The present study explores the test-retest reliability of tip, key, and palmar pinch force sense for different force levels in healthy adults during an ipsilateral force reproduction task.

Methods

Fifty-six healthy subjects were instructed to produce varying levels of reference forces (10, 30, and 50% maximal voluntary isometric contraction (MVIC)) using three types of pinches (tip pinch, palmar pinch, and key pinch) and to reproduce these forces using the same hand. The subjects were tested twice by the same experienced testers, 1 week apart.

Results

Based on the high values of the intraclass correlation coefficient (ICC), the tip pinch (0.783–0.895) and palmar pinch (0.752–0.903) force sense tests demonstrated good reliability for all the variables. The ICCs for the key pinch (0.712–0.881) indicated fair to good relative test-retest reliability.

Conclusion

1) This study demonstrates that high test-retest reliability of tip, key, and palmar pinch force sense in healthy adults can be achieved using standardized positioning and the proposed approach. 2) According to the reliability measurements, 30 and 50% maximal voluntary isometric contraction (MVIC) are the most reliable pinch force sense levels.

Work-Related Musculoskeletal Injuries in Plastic Surgeons in the United States, Canada, and Norway

BACKGROUND

Musculoskeletal injuries are more common among surgeons than among the general population. However, little is known about these types of injuries among plastic surgeons specifically. The authors' goals were to evaluate the prevalence, nature, causes, and potential solutions of these musculoskeletal injuries among plastic surgeons in three different countries: the United States, Canada, and Norway.

METHODS

A survey was e-mailed to plastic surgeons in the United States, Canada, and Norway, soliciting their demographics, practice description, history of musculoskeletal issues, potential causes of these symptoms, and proposed suggestions to address these injuries. The prevalence of various musculoskeletal symptoms was calculated, and predictors of these symptoms were evaluated using multivariate logistic regression.

RESULTS

The survey was sent to 3314 plastic surgeons, with 865 responses (response rate, 26.1 percent); 78.3 percent of plastic surgeons had musculoskeletal symptoms, most commonly in the neck, shoulders, and lower back. U.S. surgeons were significantly more likely to have musculoskeletal symptoms than Norwegian surgeons (79.5 percent versus 69.3 percent; p < 0.05); 6.7 percent of all respondents required surgical intervention for their symptoms. The most common causative factors were long surgery duration, tissue retraction, and prolonged neck flexion. The most common solutions cited were core-strengthening exercises, stretching exercises, and frequent adjustment of table height during surgery.

CONCLUSIONS

Plastic surgeons are at high risk for work-related musculoskeletal injuries. Ergonomic principles can be applied in the operating room to decrease the incidence and severity of those injuries, and to avoid downstream sequelae, including the need for surgery.

Maf for Males Performing Drilling Tasks

A laboratory experiment was conducted using the psychophysical approach to determine maximum acceptable frequency (MAF) for a simulated sheet metal drilling task under varying angles of wrist flexion. Fifteen male students served as subjects for this study. The subjects were asked to perform a simulated drilling task in five different wrist flexion postures. Results indicated that MAF was significantly reduced (p<0.001) for deviated wrist postures in the transverse plane. It was noted that there was a 33% decrease in MAF values from 0 degree wrist flexion (neutral posture) to 40 degree wrist flexion. These results imply that industrial guidelines for drilling operations involving wrist flexion must consider the MAPs in order to reduce the risk of cumulative trauma disorders.

Occupational mononeuropathies in industry

Peripheral nerve injuries have the potential to cause significant disability and can be commonly associated with recreational and occupational activities. Acute nerve injuries are mainly related to violent trauma, while repeated mechanical trauma due to external forces or repetitive motions can produce chronic nerve compression injury. This chapter will present a narrative review of the existing evidence of the association between peripheral compressive nerve disorders and work-related risk factors. Carpal tunnel syndrome (CTS) is the most common peripheral neuropathy in the general population and in working populations employed in manual repetitive and forceful activities. The work-relatedness of CTS is essentially based on epidemiologic evidence and the results of experimental studies showing the capability of repetitive wrist extreme postures, associated with hand-wrist forceful exertions, to increase the pressure inside the carpal tunnel and to compress the median nerve. Assembly industry, food processing and packaging, hand-arm vibrating tools, and jobs involving high-repetition, high-force tasks put workers at risk for CTS. Less strong evidence exists of the association between ulnar elbow neuropathy and manual tasks or repetitive stretch on squatting and peroneal nerve neuropathy at the fibular head. Very few reports are available about the association between occupation and other compressive peripheral nerve injuries.

Brachial plexopathy: a case-control study of the relation to physical exposures at work

BACKGROUND

Work-related upper limb disorders constitute a diagnostic challenge. However, patterns of neurological abnormalities that reflect brachial plexus dysfunction are frequent in limbs with pain, weakness and/or numbness/tingling. There is limited evidence about the association between occupational physical exposures and brachial plexopathy.

METHODS

80 patients with brachial plexopathy according to defined criteria and 65 controls of similar age and sex without upper limb complaints were recruited by general practitioners. Patients and controls completed a questionnaire on physical and psychosocial work-exposures and provided psychophysical ratings of their perceived exposures. The exposures of cases and controls were compared by a Wilcoxon rank sum test. Odds ratios and dose-response relationships were studied by logistic regression.

RESULTS

Whether assessed as the extent during the workday or days/week, most physical exposures, in particular upper limb posture and repetition, were significant risk indicators with clear dose-response relationships. These findings were supported by psychophysical responses that also identified perceived work pace and the use of force as risk indicators. The identified psychosocial relations were limited to measures reflecting physical exposures.

CONCLUSIONS

While the identified risk indicators have previously been associated to upper limb symptoms as well as to diagnosed disorders other than brachial plexopathy, this study indicates an association between physical and work-exposures and brachial plexopathy. Longitudinal studies should be conducted in order to exclude bias from information and selection, both of which may occur with the applied case-control design.

Impact of occupational variables in carpal tunnel syndrome

OBJECTIVE

We studied the impact of work-related factors on the outcome in patients operated for carpal tunnel syndrome.

METHODS

The population consisted of 106 CTS patients who worked at the time of operation. We registered social and occupational data from the patients.

RESULTS

Median time of sick leave was 7 weeks for the total group. Sixty-four percent reported a relationship between their work and the disease. Eighty-nine percent of the operated patients returned to their previous work after operation.

CONCLUSIONS

A majority of the patients attributed the CTS-related symptoms to their occupation. Work-related factors may therefore be one possible explanation for the socioeconomical consequences of CTS. A permanent drop-out from work in more than 1 out of 10 patients after CTS treatment indicate that CTS form a substantial socioeconomical burden in the society.

Evaluation and management of chronic work-related musculoskeletal disorders of the distal upper extremity

This clinical review will describe the epidemiology, clinical presentation, and management of the following work-related musculoskeletal disorders (WMSDs) of the distal upper extremity: deQuervain's disease, extensor and flexor forearm tendinitis/tendinosis, lateral and medial epicondylitis, cubital tunnel syndrome, and hand-arm vibration syndrome (HAVS). These conditions were selected for review either because they were among the most common WMSDs among patients attending the New York State Occupational Health Clinics (NYSOHC) network, or because there is strong evidence for work-relatedness in the clinical literature. Work-related carpal tunnel syndrome is discussed in an accompanying paper. In an attempt to provide evidence-based treatment recommendations, literature searches on the treatment of each condition were conducted via Medline for the years 1985-1999. There was a dearth of studies evaluating the efficacy of specific clinical treatments and ergonomic interventions for WMSDs. Therefore, many of the treatment recommendations presented here are based on a consensus of experienced public health-oriented occupational medicine physicians from the NYSOHC network after review of the pertinent literature. A summary table of the clinical features of the disorders is presented as a reference resource.

Clinical evaluation and management of work-related carpal tunnel syndrome

Carpal tunnel syndrome (CTS) is a clinical entity characterized by pain, paresthesias, and numbness in the distribution of the median nerve with weakness and atrophy of the thenar muscles in advanced cases. It is universally accepted that CTS is the clinical concomitant of compression of the median nerve as it passes through the carpal canal. It is reported to be the most common of the entrapment neuropathies. Increasing evidence suggests that occupational factors, including forceful use of the hands, repetitive use of the hands, and hand-arm vibration, are etiologic for CTS. When occurring as a result of occupational exposures, the term "work-related carpal tunnel syndrome" is applied. Clinical approaches to the diagnosis and treatment of work-related CTS are described in this paper. Particular attention is paid to the clinical features and pathophysiology of CTS, the epidemiology of work-related CTS, ascertainment of work-relatedness in the clinical setting, treatment including both work and non-work interventions, and control of occupational ergonomic risk factors that may contribute to the illness.

Repetitive strain injury in computer keyboard users: pathomechanics and treatment principles in individual and group intervention

Computer users experience high rates of injury and disability, broadly termed repetitive strain injury (RSI). With more than 60 million Americans using computers in offices and homes, the potential magnitude of the RSI problem indicates a need for increased attention to prevention and treatment. The purpose of this article is to: 1) present a conceptual model of RSI as a kinetic-chain, multifactorial disorder; 2) outline the salient features of the clinical evaluation of the RSI patient; 3) describe the role of postural deviation in the pathogenesis of RSI; 4) present the principles of individual manual therapy; and 5) discuss the rationale, admission criteria, educational principles, and outcome of a multidisciplinary group intervention.

Fingertip loading and carpal tunnel pressure: differences between a pinching and a pressing task

Carpal tunnel syndrome may be caused by repeated or sustained elevated carpal tunnel pressure. This study examined the relationship between carpal tunnel pressure, posture, and fingertip load. In 20 healthy individuals, carpal tunnel pressure was measured with a catheter inserted into the carpal tunnel of the dominant hand and connected to a pressure transducer. With the wrist in a pressure-neutral position, the subjects pressed on a force transducer with the index finger to levels of 0, 5, 10, and 15 N. They then pinched the transducer at the same levels of force. For both fingertip-loading postures, the carpal tunnel pressure increased with increasing fingertip load. Carpal tunnel pressures were significantly greater (p < 0.015) for the pinching task (14.2, 29.9, 41.9, and 49.7 mm Hg [1.89, 3.99, 5.59, and 6.63 kPa] for 0, 5, 10, and 15 N force levels, respectively) than for simple finger pressing (7.8, 14.1, 20.0, and 33.8 mm Hg [1.04, 1.88, 2.67, and 4.51 kPa]). This study indicates that although the external load on the finger remained constant between the two tasks, the internal loading, as measured by carpal tunnel pressure, experienced a near 2-fold increase by using a pinch grip. These findings should be given consideration in designing work tasks and tools because relatively low fingertip forces, especially in a pinch grip, elevate carpal tunnel pressures to levels that, if prolonged, may lead to the development or exacerbation of carpal tunnel syndrome.

Medical and functional status of adults with cerebral palsy

One hundred and one adults (19 to 74 years of age) with cerebral palsy were interviewed and examined. There were 52 subjects with dyskinesia, 28 with spastic quadriparesis, 11 with spastic diplegia, and 10 with spastic hemiplegia. Neuromuscular dysfunction was mild in two cases, moderate in 72 and severe in 27. 76 per cent of the subjects had multiple musculoskeletal problems. In 63 per cent, these occurred under 50 years of age, suggesting that abnormal biomechanical forces and immobility had led to excessive physical stress and strain, overuse syndromes, and possibly early joint degeneration. A number of the patients had urinary complaints due to difficulties with toilet accessibility and possible neurogenic bladder. General health care seemed satisfactory for acute illnesses, but preventive health care was almost totally lacking. Treatment for the musuculoskeletal system and availability of adaptive devices were less adequate than for children with cerebral palsy.

Repetitive industrial work and neck and upper limb disorders in females

A cross-sectional study was performed in which physical examinations of the neck and upper limbs were conducted on 82 currently working female industrial workers with exposure to repetitive work tasks and on 64 currently working referent subjects without exposure to repetitive work tasks. Associations between results of symptom questions and physical examination were sought with variables related to the work environment and to the individuals. In a multivariate model, there were statistically significant associations between exposure to repetitive work and diagnoses in both the neck/shoulders (prevalence odds ratio, POR = 4.6) and elbows/hands (POR = 3.5). In addition, age (POR = 1.9, 75th vs. 25th percentiles), tendencies towards subjective muscular tension (POR = 2.3), and stress/worry (POR = 1.9) were also associated with diagnoses in the neck/shoulders; however, there was not an association between these variables and the prevalence of diagnoses in elbows/hands. Standardized evaluation of videotape recordings in 74 of the industrial workers revealed significant associations between neck flexion, and elevation and abduction of the arm and the prevalence of neck/shoulder diagnoses. In the multivariate model, neck flexion was significantly associated with diagnoses in the neck/shoulders (p = 0.005). In addition, low muscle strength, lack of emotional well-being at work, and a variety of psychosomatic symptoms were associated with diagnoses in the neck/shoulders (all p < 0.001). Lack of strength was also associated with disorders of elbows/hands (p = 0.007). This study demonstrated a substantial prevalence of neck and upper limb disorders associated with repetitive work performed with a flexed neck and elevated and abducted arms, as well as a possible potentiation of these ergonomic factors by certain personal traits in some workers.

Bilateral median and ulnar neuropathy at the wrist in a parquet floorer

Many cases of work related compression neuropathy of the ulnar and median nerves at the wrist have been described. This report presents a case of bilateral distal neuropathy of the median and ulnar nerves in a parquet floorer, who laid wooden block flooring by hand and used the palms and volar surface of both hands to hit the blocks into place. He also used an electric sander and polisher. Bilateral numbness and paraesthesias in all fingers had been present for about one year. Clinical examination was normal; the neurological assessment indicated slight impairment in response to tactile, heat, and pain stimuli in all 10 fingers. Electroneurography showed increased distal motor latencies of median and ulnar nerves at both wrists, although the lower limbs were normal. The results of blood, urine, and instrumental tests excluded systemic disease or local factors that could cause compression neuropathy. After stopping work for three months, the clinical picture and electroneurographic results improved. These data support the hypothesis that the damage to the median and ulnar nerves had been caused by the patient's way of working, which provoked repeated bilateral microtrauma to his wrists. To diagnose work related multiple neuropathy can be difficult and an accurate work history is necessary. Preventive measures and diligent health care are required for this category of worker.

Effect of lumbrical muscle incursion within the carpal tunnel on carpal tunnel pressure: a cadaveric study

Lumbrical muscle incursion within the carpal tunnel has been implicated as a possible cause of carpal tunnel syndrome. During finger flexion, surgeons have observed the presence of lumbrical muscles in the carpal tunnel. However, the significance of this incursion has not been evaluated. To evaluate the effect of lumbrical muscle incursion within the carpal tunnel as a cause of carpal tunnel syndrome, carpal canal pressures were measured in cadaver hands at the level of the hamate hook for four finger positions: (1) 100% finger flexion; (2) 75% finger flexion; (3) 50% finger flexion; and (4) full extension. After measuring carpal tunnel pressures for each position, the lumbrical muscles were excised and the pressures were again recorded. A progressive increase in carpal tunnel pressure was noted for each degree of finger flexion in the group with intact lumbricals. This is in sharp contrast to a relatively stable carpal tunnel pressure during finger flexion for the group without lumbrical muscles. Two-way repeated measures analysis of variance revealed a significant difference in carpal tunnel pressure for both variables, lumbrical muscles and finger position. One-way repeated measures analysis of variance for carpal tunnel pressures demonstrated that the effect of finger position was significant for the group with intact lumbricals but not for the group with lumbricals removed. We conclude that lumbrical muscle incursion into the carpal tunnel can result in elevation of carpal tunnel pressure in cadaver hands and could be a variable in the cause of work-related carpal tunnel syndrome.

Occupation and the carpal tunnel syndrome

Repetitive physical tasks, particularly executed with force or using vibrating hand tools, carry the chief risk of carpal tunnel syndrome for workers. Treatment may require removing the worker from the task or redesigning the task for the worker, while proper attention to ergonomics can prevent carpal tunnel injuries in the first place.

Evaluating the fit of ambidextrous and fitted gloves: implications for hand discomfort

Ambidextrous gloves stretch significantly more and exert greater force than fitted gloves when worn. Over time, this force could contribute to vascular constriction, nerve compression, muscle fatigue and hand pain. This study suggests that research on the effects of glove use by dental care personnel is needed.

Lumbrical muscle incursion into the carpal tunnel during finger flexion

Carpal tunnel syndrome is one of the many so-called cumulative trauma disorders thought by some to be related to the performance of repetitive tasks in the work-place. The cause of this disorder is unknown. We have observed lumbrical muscle incursion into the carpal tunnel during finger flexion. This study was conducted to determine the amount of this incursion in normal wrists. Five cadaver upper limbs were analyzed radiographically with radiopaque markers on the flexor retinaculum and the lumbrical muscle origins in four finger positions: full extension, 50% flexion, 75% flexion, and 100% finger flexion. The lumbrical muscle origins were an average of 7.8 mm distal to the carpal tunnel in full finger extension. They moved an average of 14 mm into the carpal tunnel with 50% finger flexion, 25.5 mm with 75% flexion, and 30 mm with 100% flexion. Abnormal lumbrical muscles have been cited as a possible cause of carpal tunnel syndrome. These findings suggest that lumbrical muscle incursion during finger flexion is a normal occurrence and is a possible cause of work-related carpal tunnel syndrome.

Carpal tunnel syndrome among grocery store workers

The California Department of Health Services evaluated carpal tunnel syndrome (CTS), a median nerve entrapment condition associated with forceful and repetitive wrist motion, among grocery store workers at a large California supermarket where a CTS cluster had been reported. Forceful and repetitive wrist motion was measured, in three exposure levels, through a job classification scheme based upon type of work tasks and average time per week spent performing these tasks. A medical questionnaire and measurements of median sensory nerve conduction were used to measure CTS. CTS prevalence was 23% based upon a sample of 56 participants drawn from a workforce of 69 employees. A relative risk of 8.3 (95% confidence interval 2.6-26.4) for a history of CTS-like symptoms between the high and low exposure level groups held up after adjustment for the potential confounders of age, sex, alcohol consumption, and high-risk medical history. It was concluded that the basic principles of good ergonomic design should be used to prevent or diminish the risk of musculoskeletal injury in the workplace.

Work-related chronic injuries of the forearm and hand: their specific diagnosis and management

Work-related chronic injuries occur in muscles, tendons, and nerves. Epidemiological, histological, and physiological data confirm their often disputed physical basis. Terms such as repetitive strain injury and cumulative trauma disorder, when used as a diagnosis, have obscured the issue for they are really statements of causation. Definitive diagnosis is required both to treat and prevent such injuries. Precise terminology that identifies the tissue and its pathology is required. A detailed assessment methodology is described that allows a precise diagnosis. A clear relationship to work stress is necessary both to establish the cause and formulate prevention strategies. Treatment must begin early and be appropriate to the tissue and the nature of the injury. Examples are presented and discussed. Early treatment begins before too much damage has been done and yields better results.

Hand abnormalities are strongly associated with the duration of diabetes mellitus

OBJECTIVES

To study the prevalence of hand abnormalities in diabetic patients and to evaluate associations between the hand abnormalities and diabetic variables, ergonomic factors and smoking habits.

DESIGN

Cross-sectional study of 100 patients selected at random. Setting. Out-patient clinic, Department of Internal Medicine, Orebro Medical Centre Hospital in Sweden.

MAIN OUTCOME MEASURES

Presence and extent of carpal tunnel syndrome (CTS), Dupuytren's contracture (DC), flexor tenosynovitis (FTS), and limited joint mobility (LJM). Duration of diabetes, metabolic control, chronic diabetic complications, blood pressure, ergonomic factors and smoking habits.

RESULTS

Carpal tunnel syndrome, DC, FTS and LJM were each present in about 20% of the patients. Hand abnormalities were observed in 50 patients and more than one abnormality was found in 26 of the patients. The hand abnormalities were associated with the duration of diabetes but not with the metabolic control or with other diabetic complications. However, the diabetic complications were associated with bad metabolic control and with the duration of diabetes. Hand abnormalities correlated with heavy manual work but not with smoking habits. Twenty-five of the 50 patients with hand syndromes were disabled to such an extent that surgery was recommended.

CONCLUSION

The prevalence of hand abnormalities in diabetic patients is high and increases with the duration of diabetes. In many cases patients with hand abnormalities can be helped by surgery.

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.

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.

Occupational risk factors associated with soft tissue disorders of the shoulder: a review of recent investigations in the literature

Cumulative trauma illness currently accounts for over half of all occupational illness in the United States. From 1987 to 1989 there was a 100% increase in the reported number of cases of cumulative trauma illness (Bureau of Labor Statistics 1990). Shoulder region pain ranks second only to low back and neck pain in clinical frequency, and the occurrence of occupational shoulder illness is on the rise. This paper summarizes findings of a subset of recent epidemiologic, laboratory, and field studies conducted in order to identify occupational risk factors for cumulative trauma disorders (CTDs) of the shoulder region. These studies have identified the following risk factors as being associated with particular shoulder pain syndromes: awkward or static postures, heavy work, direct load bearing, repetitive arm movements, working with hands above shoulder height, and lack of rest. The paper begins with a discussion of several shoulder disorders, includes problems in studying cumulative trauma, presents results of recent studies, and concludes with suggested ergonomic controls that could help to reduce the incidence of shoulder disorders, by eliminating or reducing exposure to the associated risk factors.

Use of provincial health insurance plan billing data to estimate carpal tunnel syndrome morbidity and surgery rates

Following a work refusal at a plant manufacturing ice cream novelties in Ontario, we were asked to document cases of cumulative trauma disorders (CTDs) and carpal tunnel syndrome (CTS) in this workplace. There were 17 employees with possible hand and wrist problems identified from Workers Compensation Board (WCB) Forms, and from a list prepared at the time of the refusal. After obtaining consents, confirmations of the diagnoses of CTDs, CTS, and of surgical procedures for CTS were obtained from the physicians involved. The relative risk for these disorders among plant employees was estimated in two ways: 1) the rate of CTS operations between 1979 and 1990 was compared to that in the general population using Ontario Health Insurance Plan (OHIP) data on physicians' billings for these operations; and 2) the frequency of WCB first payment claims for tendinitis and CTS during 1987 to 1989 at the plant was compared to that among the entire labor force of Ontario. CTDs had been diagnosed in all 17 workers: 9 had had operations for CTS, but one had had this operation prior to working at the plant. Compared to the remaining 8 workers who had CTS operations, an estimated 0.08 CTS operations would be expected among the 150 employees on the plant's seniority lists between 1979 and 1990, if the estimated rates in the general population were present at the plant, giving a Standardized Morbidity Ratio of 10.0 (95% confidence interval [CI] 4.3-19.7; one-sided p = 2.1 x 10(-6)). There were 6 WCB claims for tendinitis and CTS among plant employees during 1987 through 1989. This frequency was about 68 times that in the entire Ontario labor force (95% CI 24.7-150). This investigation has shown that CTDs, and particularly CTS, documented by medical records, have occurred at least 10 times more frequently than expected at this plant. Use of health insurance billing data to estimate CTS operation rates represents a simple method for estimating the burden of illness at the individual plant level due to CTS (at least for that portion proceeding to surgery), using an objective outcome that can be confirmed from medical records.

Biomechanical analysis of upper extremity risk in Sign Langauge Interpreting

Upper extremity cumulative trauma distorders (UECTD) have been identified as an occupational health problem in professional Sign Language Interpreters (SLI). A previous study of UECTD in SLI has indicated significant differences between interpreters working with pain and those working without pain. This earlier research focused on gross measures of hand/wrist movement, work/rest cycles, and deviations from an optimal work envelope. The present paper describes a detailed biomechanical analysis of wrist and forearm activity associated with SLI. This assessment included forearm (flexion and extension) and wrist (flexion/extension and radial/ulnar deviation) measures of movement frequency, counts of individual motion, joint movement velocities and accelerations as well as range of motion. The analyses revealed that the postures required for interpreting result in the signing hand frequently held in a fully pronated position, with the palm facing out. The wrist was most frequently in an ulnar deviation and/or extension while the elbow was flexed more than 90° and held in close to the body with the fingers pointing up. The frequency of motions for the forearm and wrist were observed to be 270 per minute (4.5 Hz), which is equivalent to 13,600 per 50 minute lecture hour. The mean absolute joint movement velocity and acceleration values were relatively high in contrast to industrial jobs with wrist and forearm accelerations between 34,754 degreees/sec(2) and 36,046 degrees/sec(2), respectively. The findings from this biomechanical analysis indicates that SLI can involve highly repetitive, awkward movements with significant accelerations of the hand and wrist. Such job characteristics may predispose interpreters to upper extremity CTD-related disorders.

A cross-sectional study of hand/wrist symptoms in female grocery checkers

A questionnaire was mailed, in 1986, to 1,345 grocery checkers who belonged to one union local in south-central California. Among the 1,058 female respondents (82% response rate), we found a 12% prevalence of hand/wrist symptoms characteristic of carpal tunnel syndrome (CTS). Symptom prevalence was positively associated with age, average work hours per week, years worked as a checker, and use of diuretics. The estimated effect of years worked as a checker was greater for younger subjects than for older subjects, in whom the association reversed, suggesting the selective loss of symptomatic workers from their jobs (a form of the healthy-worker effect). Although no effects were found for specific job-related activities, we estimate that CTS symptoms in at least three of every five symptomatic workers were attributable to occupational exposures.

Workplace ergonomic factors and the development of musculoskeletal disorders of the neck and upper limbs: a meta-analysis

In the past 10 years there has been growing awareness among occupational health professionals worldwide of the large burden of illness associated with musculoskeletal disorders of the neck and upper limbs. It has been suggested that these disorders are associated with highly repetitive work and are due, at least in part, to ergonomic factors. This review examines the epidemiologic evidence of the relationship between workplace ergonomic factors such as repetition, force, static muscle loading, and extreme joint position and the development of muscle, tendon, and nerve entrapment disorders of the neck and upper limbs of exposed workers. An extensive search for relevant studies was undertaken. Of 54 potentially relevant studies identified, three met the a priori inclusion criteria. The validity of these studies was assessed, and one study was found to have major flaws. Criteria to demonstrate causality were also applied and were met in the most rigorously conducted study. When the results of these studies are compared and aggregated where appropriate, they provide strong evidence of a causal relationship between repetitive, forceful work and the development of musculoskeletal disorders of the tendons and tendon sheaths in the hands and wrists and nerve entrapment of the median nerve at the carpal tunnel. The comparison of exposed to controls for hand/wrist tendinitis gives an unadjusted common odds ratio of 9.1 (95% CI 4.9-16.2). The adjusted odds ratio for carpal tunnel syndrome is 15.5 (95% CI 1.7-141.5) based on the most rigorous study.

Overuse syndrome in musicians. When playing an instrument hurts

Musicians with overuse syndrome most commonly present with pain, inflammation, and soreness. The patient history and physical examination are the best diagnostic tools. Treatment may involve rest, splinting, and drug intervention. After the pain has subsided, progressive exercises may be appropriate. Prognosis is best with early detection and treatment.

Cumulative trauma disorders: their recognition and ergonomics measures to avoid them

Cumulative Trauma Disorders, CTD, are the summary results of many microtrauma. Though known since the early 1800s, they have become a matter of urgent ergonomics concern in the 1980s. They are usually caused by repeated and/or forceful exertions, often in the hand-arm-shoulder region. They predominantly occur to soft tissues, such as tendons and ligaments, and to nerves and blood vessels. They are commonly associated with certain occupational and leisure activities. Many CTD can be avoided by a set of fairly simple and straightforward ergonomics procedures.

The selection and definition of targeted work-related conditions for surveillance under SENSOR

Lists of reportable conditions and case definitions are important tools for epidemiologic surveillance. As part of an initiative to encourage occupational disease surveillance systems linked to intervention at the state level, we have proposed a list of target conditions and are developing a set of standard epidemiologic case definitions. Experience gained from state health department pilot projects using SENSOR and other surveillance approaches will be used to promote effective condition-specific surveillance strategies on a wider scale.

Peripheral nerve disorders in instrumentalists

I evaluated 226 instrumentalists for playing-related symptoms. There were 103 players (46%) of string instruments, 7 keyboard instrumentalists (32%), 44 players (19%) of wind instruments, and 6 percussionists (3%). The mean age was 32 years; 58% were women. Sixty-five patients (29%) had a peripheral nerve disorder; 27 had symptoms of thoracic outlet syndrome; 12 had median neuropathies (carpal tunnel syndrome in 9); 9 had ulnar neuropathies; 6 had cervical radiculopathy; 5 had digital neuropathies; 3 had cranial neuropathies; and 3 had other peripheral nerve disorders. Treatment consisted of modification of playing schedules and technique, plus physical and occupational therapy in 51 and surgical procedures in 9 patients; 5 were not treated. Follow-up at 1 to 8 years showed 74% had a satisfactory result, 14% had slight or minimal improvement, and 12% had no improvement. At the time of writing, all but 4 patients remained in the music profession. It is concluded that playing-related symptoms among instrumentalists are frequently neurological in origin and that the large majority can be helped by conservative or, on occasion, surgical means.

AAEE case report #18: Ulnar neuropathy in the distal forearm

A 66-year-old professional golf instructor developed pain, numbness, and weakness in an ulnar distribution, but the lesion could not be localized to either elbow or wrist by routine nerve conduction techniques. Stimulation along serial 1-cm increments in the distal forearm disclosed a point of focal conduction block approximately 7 cm proximal to the ulnar styloid. At surgery, the flexor carpi ulnaris was enlarged, with muscle fibers extending all along the normally tendinous distal portion. A dense fibrovascular band coursed from the ulnar artery to the abnormal muscle, compressing the adjacent ulnar nerve. Intraoperative electroneurography precisely localized the area of conduction abnormality and helped identify the band as the compressing structure. Within 2 months following surgical decompression there was complete resolution of conduction block with excellent clinical recovery.

Vibration disease

Today, in this age of technology, vibration caused by machinery is an almost universal hazard. Vibration transferred from a machine to the human body may cause discomfort, a reduction of performance, and even injury. Vibratory manual tools may cause damage to the circulatory system of the upper extremities (Raynaud's syndrome), to the peripheral nerves (peripheral neuropathy), and to the bones and joints (aseptic necrosis, fatigue fractures, degenerative joint disease). Vehicles and machines causing floor vibration cause degenerative disc disease of the lumbar spine. The pathogenesis of vibration injuries is still not completely clear and there is no effective treatment. Some of the abnormalities are irreversible and may cause permanent decrease of working ability, and even unemployment. This is why prevention is so important. Prevention is complex, including technical and organizational measures, use of individual protective clothing and footwear, and medical supervision both before and during employment. Workers who are exposed to vibration should be protected against other aggravating factors such as cold and noise, etc. Vibration-induced injuries are recognized in law in many countries as grounds for financial compensation. Their cost to industry is rising and, unless a means of prevention or cure is found, will continue to do so in the foreseeable future.

Self-reported musculoskeletal complaints among garment workers

One hundred forty-four sewing machine operators answered questionnaires concerning occupational history and musculoskeletal symptoms adapted from the National Health and Nutrition Examination Survey. They were matched for age within 5 years, race, and sex with persons completing the HANES I Augmentation Survey, and the prevalence of self-reported musculoskeletal morbidity was compared. Operators complained significantly more often of knee pain (prevalence odds ratio [POR] = 1.84, p = .0001) and knee swelling (POR = 9.98, p less than .00001), although they were no more likely to have had knee surgery. Similar increases were reported for upper-back pain (POR = 2.13, p = .002) joint ache, and joint swelling (both were significant for fingers, wrists, elbows, and shoulders at p less than .05 levels). No differences in low-back pain or in hospitalization for joint conditions were noted. Ergonomic redesign of sewing machines needs to address knee and upper-back movements as well as the arm, wrist, and finger movements.

Neurologic syndromes from repetitive trauma at work

Overuse syndrome and peripheral nerve entrapment syndromes arise in work situations in which the body is stressed beyond its limits by cumulative, repetitive trauma. These syndromes arise in some nonwork situations as well. When such an injury occurs, prompt diagnosis, treatment, and retraining aid in returning the employee to work. Prevention, of course, is the ultimate goal. This can be accomplished with close attention to basic ergonomic principles, from the design of work stations to the use of proper body mechanics.

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.

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).

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.