44038814
Upper limb disorders among biomedical laboratory workers using pipettes
Abstract Laboratory workers engaged with biomedical work often process series of specimens by repetitive or static manual activities. The widespread use of stamp pipettes has in particular been suspected to entail upper-limb disorders. Our primary aim was to test, if cumulated pipette work is associated with self-reported and clinically examined upper-limb disorders. Additionally we explored, if non-pipette repetitive or static laboratory tasks are associated with upper-limb complaints. We also explored, if use of electrically driven pipettes (reducing the forces needed to activate the pipette) are in lesser degree associated with upper limb complaints than manually driven pipettes. In all, 1,398 female laboratory technicians at two workplaces were included in a questionnaire survey. Among 1,202 respondents, 167 cases with significant upper-limb symptoms and 134 controls without participated in a case-control study. Amount of pipette work (especially when cumulated over the last 2 years) was associated with symptoms in dominant upper limb, especially in the hand/wrist and thumb, and with impingement syndrome and muscle pain in dominant shoulder. Use of electrical pipettes did not modify this association. The non-pipette tasks were at highest vaguely related to upper-limb symptoms. In biomedical laboratory work, intensive pipette use seems to constitute a dominating major ergonomic problem.
19219454
Hand and shoulder ailments among laboratory technicians using modern plunger-operated pipettes.
Laboratory technicians working with plunger-operated pipettes have a monotonous work task loading the arm. A study was performed to evaluate the prevalence of hand and shoulder ailments among laboratory technicians in relation to the 'dose' of pipetting and relation to some psychosocial factors was used to compare a cohort of 128 females employed by university research laboratories with reference data obtained from 25 378 female Swedish state employees in general. The prevalence of hand ailments among the laboratory assistants was found to be twice that among female state employees in general. In the cohort a nested case-control study indicated that an increased risk of hand (OR = 5, 0) and shoulder (OR = 2, 4) ailments was associated with more than 300 h/year pipetting. Suggestions for permissible exposure levels for pipetting are presented.
26146282
Ergonomic intervention: its effect on working posture and musculoskeletal symptoms in female biomedical scientists.
This study investigates the effect of ergonomic intervention on working posture and musculoskeletal symptoms in female biomedical scientists. The Nordic musculoskeletal questionnaire (NMQ), body discomfort chart (BDC) and rapid upper-limb assessment (RULA) are the tools for assessment. The study was conducted in three phases: pre-intervention, intervention and post-intervention. Pre-intervention, 79% of subjects reported a three-month prevalence of symptoms, and these were reported more frequently by those working in haematology/transfusion. Analysis by RULA showed that the majority (59%) of postures had a grand score of four. A further 24% had scores of five or six. The highest frequency of poor postures was seen in haematology/transfusion. Intervention comprised physical workplace changes, a seminar, and advice on risk factors. In the post-intervention phase, baseline measurements were repeated. Reporting of three-month prevalence of symptoms had decreased to 54%, and reports of body discomfort also had decreased. The majority (64%) had a RULA grand score of three. No observed postures had scores of five or six. In conclusion, ergonomic intervention resulted in an improvement in working postures, and a decrease in the prevalence of musculoskeletal symptoms and body discomfort. Analysis of findings indicate that RULA scores generally corresponded with reporting of symptoms (NMQ) and discomfort (BDC).
205405600
Effects of work surface height on muscle activity and posture of the upper extremity during simulated pipetting
In order to examine the effects of work surface height (WSH) on muscle activity, posture and discomfort during simulated pipetting, an experimental study was conducted using electromyography, electrogoniometry, video techniques and also qualitative data. The experimental design consisted of one independent variable (WSH with six heights) and 13 dependent variables. The levels of muscle strain and discomfort were significantly lower at the shoulder when the WSHs were low but thumb muscle activities and neck flexion levels were markedly higher at these WSHs compared to higher WSHs. To reduce shoulder strain, without raising thumb and neck strain beyond acceptable limits, the findings suggest that the height of a laboratory workbench should be at the level of the pipette tip when held in a standing position with the hand at elbow height. It was also found that pipetting should not be done in a seated posture. Practitioner Summary: An experimental study was conducted to examine the effects of work surface height on upper extremity muscle activity, posture and discomfort during simulated pipetting. The findings suggest that the laboratory workbench height should be at the pipette-tip level when held in a standing position with the hand at elbow height.
1945497
Upper limb disorder due to manual pipetting.
This case report describes the occurrence of non-specific upper limb symptoms, in a 47-year-old female scientific officer, associated, with manual pipetting. The discussion considers the difficulty of risk assessment and reduction for this common procedure.
38605508
Pipette pusher's paresthesia
A 56-year old, left-handed female laboratory analyst visited our outpatient clinic because of numbness and tingling of the tip of her left thumb which had started 2 months earlier. She had a history of migraine and was operated twice because of a lumbar disc herniation. Neurological examination revealed hypoesthesia and hypoalgesia of the tip of the left thumb. The area extended along the ventral aspect of the thumb, from distal to the interphalangeal joint to close to the tip of the thumb (Fig. 1). An absent Achilles tendon reflex was found on the right side, as a consequence of a previous lumbar disc herniation. No nerve conduction study of the digital branches of the median and radial nerve was performed, as inconsistent findings were expected, because of the small symptomatic area involved. We concluded that the paresthesia resulted from repetitive local compression by a pipette, which she often uses during her work as a laboratory analyst. Despite our instructions, the patient continued her work and sensory symptoms persisted at follow-up 2 months after her initial visit. Although she had been working in the laboratory for many years, she had never noticed these symptoms before. Nor did she experience sensory symptoms before, during other activities such as carrying shopping bags or using scissors. No other clues suggestive of a diagnosis of hereditary neuropathy with liability to pressure palsies were found. We assume that the repetitive use of the pipette resulted in demyelination by compression of a digital branch of the median nerve. This syndrome as a result of frequent pipette use has not been described before. A case describing an area of anesthesia on the middle finger, designated pen pusher’s paresthesia , has previously been described [1]. As a results of frequent writing with a pen in an administrative job, the patient experienced an area of anesthesia on the radial side of the middle finger between the distal interphalangeal joint and the tip of the finger. We think that similar local compression neuropathies in the hands are much more frequent than previously assumed.
28719665
A questionnaire survey of the ergonomic problems associated with pipettes and their usage with specific reference to work-related upper limb disorders.
This study has considered the ergonomic problems associated with the use of pipettes through a questionnaire study of users. The study groups comprised an exposed (i.e. pipette users) and a non-exposed (i.e. non-users) cohort. Eighty questionnaire responses were returned by pipette users and 85 by non-users from six organisations; a response rate of approximately 55% for each of the study cohorts. The reported occurrence of elbow and hand complaints [using the general version of the Nordic musculoskeltal questionnaire (Kuorinka et al, 1987)] was significantly higher in the pipette user population as compared to the control population. There is an increase in the percentage of those reporting hand complaints as the duration of the working period involving continuous use of pipettes increases. Almost 90% of subjects in the longest exposure group (continuous use for more than 60 min) reported hand complaints. Users identified a number of features which made plunger operated pipettes more difficult to use: almost all of the female population who reported difficulties identified plunger operation as a design deficiency. Users also identified features of the general working environment which made the pipetting tasks more difficult. The study concludes that a number of work-related factors may affect the efficiency and comfort of staff performing laboratory tasks using pipettes.
32431748
The Strain Index: a proposed method to analyze jobs for risk of distal upper extremity disorders.
Based on existing knowledge and theory of the physiology, biomechanics, and epidemiology of distal upper extremity disorders, a semiquantitative job analysis methodology was developed. The methodology involves the measurement or estimation of six task variables (intensity of exertion, duration of exertion per cycle, efforts per minute, wrist posture, speed of exertion, and duration of task per day); assignment of an ordinal rating for each variable according to exposure data; then assignment of a multiplier value for each variable. The Strain Index is the product of these six multipliers. Preliminary testing suggests that the methodology accurately identifies jobs associated with distal upper extremity disorders versus jobs that are not; however, large-scale studies are needed to validate and update the proposed methodology.
34557274
Grading the severity of chronic pain
&NA; This research develops and evaluates a simple method of grading the severity of chronic pain for use in general population surveys and studies of primary care pain patients. Measures of pain intensity, disability, persistence and recency of onset were tested for their ability to grade chronic pain severity in a longitudinal study of primary care back pain (n = 1213), headache (n = 779) and temporomandibular disorder pain (n = 397) patients. A Guttman scale analysis showed that pain intensity and disability measures formed a reliable hierarchical scale. Pain intensity measures appeared to scale the lower range of global severity while disability measures appeared to scale the upper range of global severity. Recency of onset and days in pain in the prior 6 months did not scale with pain intensity or disability. Using simple scoring rules, pain severity was graded into 4 hierarchical classes: Grade I, low disability‐low intensity; Grade II, low disability‐high intensity; Grade III, high disability‐moderately limiting; and Grade IV, high disability‐severely limiting. For each pain site, Chronic Pain Grade measured at baseline showed a highly statistically significant and monotonically increasing relationship with unemployment rate, pain‐related functional limitations, depression, fair to poor self‐rated health, frequent use of opioid analgesics, and frequent pain‐related doctor visits both at baseline and at 1‐year follow‐up. Days in Pain was related to these variables, but not as strongly as Chronic Pain Grade. Recent onset cases (first onset within the prior 3 months) did not show differences in psychological and behavioral dysfunction when compared to persons with less recent onset. Using longitudinal data from a population‐based study (n = 803), Chronic Pain Grade at baseline predicted the presence of pain in the prior 2 weeks, Chronic Pain Grade and pain‐related functional limitations at 3‐year follow‐up. Grading chronic pain as a function of pain intensity and pain‐related disability may be useful when a brief ordinal measure of global pain severity is required. Pain persistence, measured by days in pain in a fixed time period, provides useful additional information.
40055902
Identification of neck-shoulder disorders in a 1 year follow-up study. Validation of a questionnaire-based method
&NA; A cohort of 243 female sewing machine operators were studied by questionnaire and clinical examinations with the purpose to study the efficiency of a screening questionnaire‐based method to identify prevalent and incident cases of neck‐shoulder disorders. The cross‐sectional correlation between self‐reported neck‐shoulder complaints scores and clinical signs of a neck‐shoulder disorder was high. An assessed cut‐of point of complaints could identify 90% of all cases fulfilling the criteria of rotator cuff tendinitis, while the complaint score with regard to clinical signs of myofascial pain syndrome was about 67%. In the follow‐up analyses, incident clinical signs of disorders at 1 year follow‐up were used as ‘golden standard’ in the validation of screening criteria, which included a defined increase of symptoms. Apparently increase of symptoms did not seem to be the optimal criteria for identification of incident cases. Alternatively a cut‐of point of regional complaints in close relation to clinical examinations is recommended.
39453894
Articular mobility in an African population.
There is considerable variation in the range ofmovements which are possible in the joints of normal individuals. In general, females are more mobile than males, while joint laxity decreases with age (Ellis and Bundick, 1956; Wynne-Davies, 1971). Ethnic differences in joint mobility have also been described. For instance, Negroes and Indians have been shown to have a greater range of movements than Caucasians of the same age and sex (Harris and Joseph, 1949). Similarly, in an investigation in Cape Town, Indians were found to be more loose-jointed than indigenous Xhosa and Hlubi, who in turn had a greater degree of joint laxity than white South Africans (Schweitzer, 1970). Articular mobility is a graded trait and at one end of the spectrum a considerable degree of joint laxity may occur in normal individuals (Wood, 1971). Apart from this form of hypermobility, joint laxity is also a component of a variety of genetically determined syndromes (McKusick, 1966; Beighton, 1970). It can also occur in the absence of other stigmata as a simple inherited entity (Sturkie, 1941; Carter and Sweetnam, 1958, 1960; Beighton and Horan, 1970). It has been suggested that hypermobile individuals are prone to orthopaedic disorders, such as degenerative joint disease, dislocations, joint effusions, and muscular pains (Hass and Hass, 1958; Kirk, Ansell, and Bywaters, 1967; Grahame, 1971). Articular laxity has also been implicated as an important factor in the genesis of congenital dislocation of the hip (Wynne-Davies, 1970). For these reasons, hypermobility may well be of considerable clinical significance. An epidemiological survey has recently been completed among the Tswana people of the Western Transvaal. The main aims of this investigation were the study of various bone and joint conditions, but the survey also provided an excellent opportunity for the measurement of the range ofjoint movements in a large number of individuals and for the assessment of the influence of age, sex, and somatotype on their articular mobility. The importance of joint laxity in the production of non-specific musculo-skeletal complaints was also evaluated. The purpose of this paper is to present the results of this investigation and to discuss the clinical significance of the observations which were made.
83622
Impingement syndrome in athletes
Athletes, particularly those who are involved in sporting activ ities requiring repetitive overhead use of the arm (for example, tennis players, swimmers, baseball pitchers, and quarterbacks), may develop a painful shoulder. This is often due to impinge ment in the vulnerable avascular region of the supraspinatus and biceps tendons. With the passage of time, degeneration and tears of the rotator cuff may result. Pathologically, the syndrome has been classified into Stage I (edema and hemor rhage), Stage II (fibrosis and tendonitis), and Stage III (tendon degeneration, bony changes, and tendon ruptures). The im pingement syndrome may be a problem for the young, active, competitive athlete as well as the casual weekend athlete. The "impingement sign" which reproduces pain and resulting facial expression when the arm is forceably forward flexed (jamming the greater tuberosity against the anteroinferior surface of the acromion) is the most reliable physical sign in establishing the diagnosis. Flexibility exercises, strengthening programs, and special training techniques are a preventive and treatment requirement. Rest and local modalities such as ice, ultrasound, and antiinflammatory agents are usually effective to lessen the inflammatory reaction. Surgical decompression by resecting the coracoacromial ligament or a more definitive anterior ac romioplasty may rarely be indicated.
68403418
Chronic musculoskeletal injuries in the workplace
A Controversial Issue. Scientific Basis: Pathological and Clinical Basis. Muscle Pathology with Overuse. Task Analysis. Tissue Tolerance. Pain Perception. Diagnosis: Diagnostic Criteria. Physical Assessment: Neck, Shoulder and Back. Physical Assessment: Forearm, Wrist and Hand. Physical Assessment: Nerves and Vessels. Psychological Assessment. Management: Sociological Considerations. Physical Therapy for Physical Problems. When Chronic Pain Is the Problem. Mind, Body, Society, And the Workplace Environment. Appendix I: Minimum Clinical Criteria for Establishing a Provisional Diagnosis on First Assessment. Appendix II: Intake Questionnaire and Assessment Profile. Appendix III: Physical Assessment Forms. Appendix IV: Disability Assessment Forms. Appendix V: Worksite Assessment Tools.
28053426
Epidemiologic screening of occupational neck and upper limb disorders. Methods and criteria.
A method for screening occupational neck and upper limb disorders and criteria for diagnosis are presented.
8077917
Musculoskeletal disorders of the neck and upper limb among sewing machine operators: a clinical investigation.
One hundred and seven women participated in a clinical study of an age-stratified random sample of sewing machine operators compared to a group of auxiliary nurses and home helpers. Four groups, according to years of being a sewing machine operator, consisted of: (controls) 25; (0-7 years) 21; (8-15 years) 25; and (more than 15 years) 36. The numbers of the main clinical diagnoses in the four groups were: cervicobrachial fibromyalgia (myofascial pain syndrome) 2, 4, 11, 24; cervical syndrome 0, 1, 3, 10; and rotator cuff syndrome 1, 1, 6, 11. The observed exposure-response relationship between clinical outcomes and years as a sewing machine operator was maintained when adjusting for current exposure to musculoskeletal strain and other potential confounders. Muscle palpation proved to be a reproducible examination with kappa values around 0.70.
107054060
Healthy Work : Stress, Productivity, and the Reconstruction of Working Life
Suggests a strategy for redesigning jobs to reduce unnecessary stress and improve productivity and job satisfaction.
24664709
Explaining socioeconomic differences in sickness absence: the Whitehall II Study.
OBJECTIVE--To describe and explain the socioeconomic gradient in sickness absence. DESIGN--Analysis of questionnaire and sickness absence data collected from the first phase of the Whitehall II study. Grade of employment was used as a measure of socioeconomic status. SETTING--20 civil service departments in London. SUBJECTS--6900 male and 3414 female civil servants aged 35-55 years. MAIN OUTCOME MEASURES--Rates of short spells (< or = 7 days) and long spells (> 7 days) of sickness absence. RESULTS--A strong inverse relation between grade of employment and sickness absence was evident. Men in the lowest grade had rates of short and long spells of absence 6.1 (95% confidence interval 5.3 to 6.9) and 6.1 (4.8 to 7.9) times higher than those in the highest grade. For women the corresponding rate ratios were 3.0 (2.3 to 3.9) and 4.2 (2.5 to 6.8) respectively. Several risk factors were identified, including health related behaviours (smoking and frequent alcohol consumption), work characteristics (low levels of control, variety and use of skills, work pace, and support at work), low levels of job satisfaction, and adverse social circumstances outside work (financial difficulties and negative support). These risk factors accounted for about one third of the grade differences in sickness absence. CONCLUSION--Large grade differences in sickness absence parallel socioeconomic differences in morbidity and mortality found in other studies. Identified risk factors accounted for a small proportion of the grade differences in sickness absence. More accurate measurement of the risk factors may explain some of the remaining differences in sickness absence but other factors, as yet unrecognised, are likely to be important.
119351629
Applied Logistic Regression
"A new edition of the definitive guide to logistic regression modeling for health science and other applicationsThis thoroughly expanded Third Edition provides an easily accessible introduction to the logistic regression (LR) model and highlights the power of this model by examining the relationship between a dichotomous outcome and a set of covariables. Applied Logistic Regression, Third Edition emphasizes applications in the health sciences and handpicks topics that best suit the use of modern statistical software. The book provides readers with state-of-the-art techniques for building, interpreting, and assessing the performance of LR models. New and updated features include: A chapter on the analysis of correlated outcome data. A wealth of additional material for topics ranging from Bayesian methods to assessing model fit Rich data sets from real-world studies that demonstrate each method under discussion. Detailed examples and interpretation of the presented results as well as exercises throughout Applied Logistic Regression, Third Edition is a must-have guide for professionals and researchers who need to model nominal or ordinal scaled outcome variables in public health, medicine, and the social sciences as well as a wide range of other fields and disciplines"--
941775
Thumb Force and Muscle Loads Are Influenced by the Design of a Mechanical Pipette and by Pipetting Tasks
Work involving pipetting is associated with elevated rates of musculoskeletal disorders of the hand and wrist. The purpose of this study was to quantify thumb loading and muscle activity and determine if they varied among pipetting tasks. Fourteen experienced participants performed nine pipetting tasks while surface electromyography was measured for the extensor pollicis brevis, abductor pollicis longus, flexor pollicis longus, and abductor pollicis brevis muscles. For five tasks, participants used a pipette instrumented to measure the thumb force applied to the plunger. High-precision tasks significantly increased static muscle activity but reduced peak thumb force on average 5% as compared with low-precision tasks. Pipetting high-viscosity fluids increased peak thumb forces on average 11% as compared with pipetting low-viscosity fluids. Use of a latch pipette increased muscle activity of three muscles. We conclude that pipette design and pipetting tasks can influence applied thumb force and muscle activity. We recommend that pipettes be designed to limit applied peak forces and that pipette users be instructed in use patterns that will reduce applied forces. Actual or potential applications of this research include modifications to pipette designs and worker training in order to reduce hand pain associated with pipetting.
42156094
Laboratory work with automatic pipettes: a study on how pipetting affects the thumb.
The aim of this study was to assess the strain that is exerted on the thumb when working with automatic pipettes. The study consisted of three parts: a survey concerning stress-related symptoms in general and in the thumb in particular, a study of the working conditions in the laboratory with the help of a video-film, and a power test. In the survey the Nordic Council of Ministers' questionnaire and a newly developed questionnaire about the thumb were used. A usual and frequently carried out analysis that included several different methods of pipetting was filmed on video. The power test measured two things, the power that is necessary to press down the button of the pipette into different positions and the maximal strength when performing a movement in the same direction. It was shown that the strain on the thumb for a woman with weak muscular structures is unacceptably high. The symptoms increase with the amount of time spent with pipetting and with age. In addition, pipetting is done in a position where the thumb is not stable but nevertheless has to work to stabilize the grip around the pipette and to press down the button of the pipette. Therefore the muscles have to work both as mobilizing and stabilizing structures. It is concluded, therefore, that some form of automation ought to be taken into consideration if the amount of pipetting work tends to increase. The pipettes should be constructed with as little button resistance as possible and the handle should be designed to fit different hand sizes.
30824108
An ergonomic design and performance evaluation of pipettes.
This paper describes the results of an investigation of the differences in performance, postures, strains on hand-arm-shoulder musculature, and subjective ratings of three pipettes (models A, B, and C). Both models A and B were pipettes available on the market. Model C was developed for this study of an ergonomically designed pipette. The gripping posture of the three models was distinct both in the anatomical and in the functional sense. Working with models A and B required a four-finger grasp with a thumb operated plunger. Model C required a finger-palmar power grip and the plunger was operated by the fingers. Performance evaluation of the different pipettes in different tasks indicated that using the proposed model C resulted in a 2-3% lower fault rate, a 10% shorter completion time, and the highest subjective ratings among the three. Postural analysis results indicated that when using model C, the shoulder was the least abducted, the wrist was the least extended, and the wrist was the least radially extended. Model C appeared to provide the greatest opportunity for delicate adjustments of posture in response to the activity of the skin receptors and reduced the strains on the upper body musculature, justifying the ergonomic input into the design.
9719799
Ergonomic evaluation of ten single-channel pipettes.
UNLABELLED
Repetitive pipetting is a task that is associated with work-related musculoskeletal disorders of the hand and arm.


OBJECTIVE
The purpose of this study was to evaluate the usability and ergonomic performance of commercially available pipettes as determined by user ratings and objective measurements.


PARTICIPANTS
Participants were laboratory technicians and scientists at the Lawrence Berkeley National Laboratory with experience performing pipetting tasks.


METHODS
Twenty-one experienced pipette users completed a standardized pipetting task with 5 manual and 5 electronic pipettes. After using each pipette, the user rated it for attributes of comfort and usability.


RESULTS
Although no single pipette was rated significantly better than all of the others for every attribute tested, some significant differences were found between pipettes. The Rainin Pipet-Lite received the highest overall quality score among manual pipettes, while the Thermo Scientific Finnpipette Novus was the top-ranked electronic pipette. Features correlated with greater hand and arm comfort were lower tip ejection force, lower blowout force, and pipette balance in the hand.


CONCLUSIONS
The findings, when considered with participant comments, provide insights into desirable pipette features and emphasize the value of user testing and the importance of the interactions between task, workplace layout, and pipette design.
55830499
An investigation of hand forces and postures for using selected mechanical pipettes
Abstract The present study evaluated thumb, hand forces, wrist, forearm and shoulder postures used for pipetting with three selected mechanical pipettes. Twelve pipette users in a large university health system participated in pipetting simulation in their own laboratories to investigate the effects of pipette type, body posture (standing/seated), sample volume (200/1000 μL) and pipetting task on the physical risk factors. The thumb and hand forces were measured with 19 Flexiforce™ sensors. Wrist and forearm postures were measured with an electrogoniometer and a torsiometer, respectively. Humeral elevation as shoulder postural stress was assessed by observations from videos recorded during pipetting simulation. The study results showed several advantages of using the non-axial pipette over the traditional axial ones. The non-axial pipette was associated with approximately 2–6 times less thumb and hand force than the traditional axial pipettes. In addition, there were approximately 20–30% reductions in ulnar deviation and 30–70% reductions in humeral elevation to operate the non-axial pipette for most of the pipetting actions. One disadvantage of using the non-axial pipette appears to be increased forearm pronation by approximately 100–150% for the entire pipetting cycle, as compared to the axial pipettes. The results of the study may provide useful information regarding design of pipettes for reducing physical risk factors associated with pipetting. Relevance to industry This paper demonstrated hand forces and postures for common pipetting tasks with selected mechanical pipettes. The hand force and postural data for using axial and non-axial pipettes may provide key information for hand injury prevention due to pipetting in the industry.
17292142
The effect of two alternative arm supports on shoulder and upper back muscle loading during pipetting.
OBJECTIVE
Pipetting involves static upper arm positions with the pipette held away from the body for sustained periods of time, putting increased musculoskeletal load on the shoulder and upper back. This study explores the effect of using two alternative arm supports while pipetting on muscle loading in the shoulder/neck region.


PARTICIPANTS
15 experienced pipette users participated in this study.


METHODS
In a repeated-measures design, participants performed simulated pipetting in a laboratory setting under three arm support conditions: (1) a gel pad on the work surface, (2) a freely-moving counter-balanced forearm support, and (3) no support (control). Surface electromyography (EMG) of the anterior deltoid and upper trapezius muscles were recorded, as well as productivity and subjective usability.


RESULTS
Both arm support conditions resulted in significantly lower mean muscle activity of the anterior deltoid and upper trapezius muscles (p<0.001) and significantly higher subjective comfort ratings (p<0.001) compared to the control condition. The freely moving forearm support resulted in significantly lower peak muscle activity in the anterior deltoid compared to the control condition (p<0.001). Productivity was not affected by the arm supports. These findings suggest that arm support may be beneficial in reducing muscle loading and improving comfort in the shoulder and upper back during pipetting. Future studies are needed to measure the impact of these arm supports in the workplace.
35552126
Inverse dynamic analysis of the biomechanics of the thumb while pipetting: a case study.
Thumb-push manual pipettes are commonly used tools in many medical, biological, and chemical laboratories. Epidemiological studies indicate that the use of thumb-push mechanical pipettes is associated with musculoskeletal disorders in the hand. The goal of the current study was to evaluate the kinematics and joint loading of the thumb during pipetting. The time-histories of joint angles and the interface contact force between the thumb and plunger during the pipetting action were determined experimentally, and the joint loadings and joint power in the thumb were calculated via an inverse dynamic approach. The moment, power, and energy absorption in each joint of the thumb during the extraction and dispensing actions were analyzed. The results indicate that the majority of the power is generated in the interphalangeal (IP) and carpometacarpal (CMC) joints for the pipetting action. The analysis method and results in the current study will be helpful in exploring the mechanism for musculoskeletal injuries of the hand associated with pipetting, providing a preliminary foundation for ergonomic design of the pipette.
109661796
Ergonomics and the usability of mechanical single-channel liquid dosage pipettes
Abstract The aim of this study was to compare the ergonomics and usability of five mechanical single-channel pipettes as healthy female laboratory workers ( N = 1 1 ) performed pipetting tasks in simulated work situations. The muscular activity, wrist angle, perceived musculoskeletal strain, perceived features of usability, and work efficiency of each worker were measured during 1 day. Muscular activity of the musculus flexor pollicis longus ( p 0.0 0 1 ), ulnar deviation of the right wrist ( p 0.0 0 1 ), and perceived strain of the shoulder, forearm, wrist and thumb ( p 0.0 1 ) after the pipetting task were the least when the shortest and lightest pipette with the thickest handle and with three different sizes (small, medium, large) was used. The longest pipette and the second heaviest pipette caused the least perceived strain in the right-hand fingers. The shortest and lightest pipette with the thickest handle and with three different sizes earned the best average assessments for most of the usability features. No differences were found in work efficiency when the different pipette models were used. Relevance to industry The results of this study can be of value when pipettes are being designed and tested and when the ergonomics of work in laboratories is under development.
22686049
Risk factors in the onset of neck/shoulder pain in a prospective study of workers in industrial and service companies
Aims: To quantify the relative contribution of work related physical factors, psychosocial workplace factors, and individual factors and aspects of somatisation to the onset of neck/shoulder pain. Methods: Four year prospective cohort study of workers from industrial and service companies in Denmark. Participants were 3123 workers, previously enrolled in a cross sectional study, where objective measurement of physical workplace factors was used. Eligible participants were followed on three subsequent occasions with approximately one year intervals. Outcomes of interest were: new onset of neck/shoulder pain (symptom cases); and neck/shoulder pain with pressure tenderness in the muscles of the neck/shoulder region (clinical cases). Results: During follow up, 636 (14.1%) participants reported neck/shoulder pain of new onset; among these, 82 (1.7%) also had clinical signs of substantial muscle tenderness. High shoulder repetition was related to being a future symptom case, and a future clinical case. Repetition was strongly intercorrelated with other physical measures. High job demands were associated with future status as a symptom case, and as a clinical case. A high level of distress predicted subsequent neck/shoulder pain, and neck/shoulder pain with pressure tenderness. Conclusions: High levels of distress, and physical and psychosocial workplace factors are predictors of onset of pain in the neck and/or shoulders, particularly pain with pressure tenderness in the muscles.
41976370
Associations between work-related factors and specific disorders of the shoulder--a systematic review of the literature.
OBJECTIVE
Our aim was to provide a quantitative assessment of the exposure-response relationships between work-related physical and psychosocial factors and the occurrence of specific shoulder disorders in occupational populations.


METHODS
A systematic review of the literature was conducted on the associations between type of work, physical load factors, and psychosocial aspects at work, on the one hand, and the occurrence of tendinitis of the biceps tendon, rotator cuff tears, subacromial impingement syndrome (SIS), and suprascapular nerve compression, on the other hand. Associations between work factors and shoulder disorders were expressed in quantitative measures as odds ratio (OR) or relative risk (RR).


RESULTS
The occurrence of SIS was associated with force requirements >10% maximal voluntary contraction (MVC), lifting >20 kg >10 times/day, and high-level of hand force >1 hour/day (OR 2.8-4.2). Repetitive movements of the shoulder, repetitive motion of the hand/wrist >2 hours/day, hand-arm vibration, and working with hand above shoulder level showed an association with SIS (OR 1.04-4.7) as did upper-arm flexion > or =45 degrees > or =15% of time (OR 2.43) and duty cycle of forceful exertions > or =9% time or duty cycle of forceful pinch >0% of time (OR 2.66). High psychosocial job demand was also associated with SIS (OR 1.5-3.19). Jobs in the fish processing industry had the highest risk for both tendinitis of the biceps tendon as well as SIS (OR 2.28 and 3.38, respectively). Work in a slaughterhouse and as a betel pepper leaf culler were associated with the occurrence of SIS only (OR 5.27 and 4.68, respectively). None of the included articles described the association between job title/risk factors and the occurrence of rotator cuff tears or suprascapular nerve compression.


CONCLUSIONS
Highly repetitive work, forceful exertion in work, awkward postures, and high psychosocial job demand are associated with the occurrence of SIS.
12508022
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.
7328086
User-oriented evaluation of mechanical single-channel axial pipettes.
Hand tools should be designed so that they are comfortable to use, fit the hand and are user-oriented. Six different manual, single-channel axial pipettes were evaluated for such objective outcomes as muscular activity, wrist postures and efficiency, as well as for subjective outcomes concerning self-assessed features of pipette usability and musculoskeletal strain. Ten experienced laboratory employees volunteered for the study. The results showed that light and short pipettes with better tool comfort resulted in reduced muscular activity and perceived musculoskeletal strain when they were compared with a long and heavy pipette. There were no differences in the efficiency between the different pipettes. Combining both the objective and subjective measures enabled a broader evaluation of product usability. The results of this study can be used both in product development and as information on which to base the purchase of new pipettes for laboratory work.
19622075
Effect of speed and precision demands on human shoulder muscle electromyography during a repetitive task
Abstract Effects of speed and precision on electromyography (EMG) in human shoulder muscles were studied during a hand movement task where five points were marked repeatedly with a pencil. Six female subjects performed with three precision demands and at four speeds. Three of the speeds were predefined, while the last speed was performed as fast as possible. The EMG were recorded from 13 shoulder muscles or parts of muscles. Elbow velocity, acceleration and rectified EMG were calculated for each task. The mean elbow velocity and acceleration increased with speed and precision demands. There was an increase in EMG as the speed demand increased for all three precision demands (P < 0.001), and as the precision demand increased for the two highest predefined speed demands (P < 0.05). The combination of a high speed and a high precision demand resulted in the highest EMG. Different EMG levels were attained for the 13 muscles and the supraspinatus muscle always showed the highest normalized EMG. However, analysis of variance showed the same relative increase for all muscles with speed and precision demands. The EMG changes in response to precision demand can only be explained in part by the differences in movement velocity and acceleration, and other factors such as increased co-contraction must also be taken into account.
21846700
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.
2122550
Validity of a Self-Administered Questionnaire for Assessing Physical Work Loads in a General Population
Learning ObjectivesDescribe the design and rationale for this study evaluating eight questions on perceived physical load that are commonly a part of public health questionnaires.Recount the findings on validity of the eight physical-load questions, and the implications for which questions may be retained and which should be redesigned.Explain whether and how these findings were influenced by gender, type of work, and the presence of musculoskeletal complaints. The aim of the study was to evaluate eight questions concerning physical loads, used in public health questionnaires. Working women and men (203) completed a self-administered questionnaire twice, following a test-retest method. The questions were also validated with a structured interview. Response agreement was calculated with Cohen’s &kgr; statistics with quadratic weights (&kgr;w). Test-retest agreement varied from 0.74 to 0.92, and inter-method agreement from 0.38 to 0.81. The lowest coefficients were for the questions concerning bent/twisted work postures (&kgr;w 0.38) and repetitive movements (&kgr;w 0.39). The results did not indicate any substantial influence of gender, type of work or musculoskeletal complaint. The questions concerning general physical activity and sitting work postures, and physical exercise/sports during leisure times, had good validity. The questions concerning bent/twisted work posture and repetitive movements need to be re-designed.
36297014
Validity of self-reported physical work load in epidemiologic studies on musculoskeletal disorders.
OBJECTIVES
This study assessed the validity of self-reported physical work load by questionnaire and logbook against task analysis and observation. It also investigated factors (job type and low-back or neck pain) affecting the self-assessment of physical work load and compared the assessments between the questionnaire and the logbook.


METHODS
A self-administered questionnaire including 10 questions (ordinal scales) on physical work load and musculoskeletal symptoms was filled out by 2756 men in the forest industry. From this population, 36 men were selected for task analysis and observation. Logbooks including 10 continuous variables were analyzed for 386 men.


RESULTS
The Spearman rank correlation coefficients between the self-assessments and observations for the frequency of manual handling, duration of trunk flexion, neck rotation, hand above shoulder level, and squatting or kneeling ranged between 0.42 and 0.55. The correlation coefficients for the questionnaire items were higher in general, and the accuracy better, for those with no low-back pain than for those with pain. The duration of trunk flexion, neck flexion and hand above shoulder level was overestimated in the questionnaires and less so in the logbooks.


CONCLUSIONS
Self-administered questionnaires may help to classify groups with heterogeneous occupational tasks according to some work-load factors. The accuracy of the assessments is not good for studying quantitative exposure-effect relationships, however. The logbook method might give more valid information. The perception of musculoskeletal pain may bias the self-assessment of work load.
5871248
Interview versus questionnaire for assessing physical loads in the population-based MUSIC-Norrtälje Study.
BACKGROUND
MUSIC-Norrtälje study is a case-referent study, the aim of which is to find risk and health factors for low back and neck/shoulder disorders. In this part of the study, the interview technique and the self-administered questionnaire used for assessment of physical loads are described and the inter-method reliability of parts of the self-administered questionnaire is estimated. The distribution of exposure levels in a general population is also described.


METHODS
The study period was three years from November 1993 to November 1996, and the study subjects totaled 2,480 persons (813 female and 610 male referents, 380 female and 315 male low back cases, 252 female and 106 male neck/shoulder cases). The interview concerned "a typical working day" during the preceding 12 months and comprised assessment of energy expenditure, work postures, and manual materials handling for work and leisure time, including regular sport activities. The self-administered questionnaire comprised 18 questions, each covering 5 different points of time: right now, 5, 10, 15, 20 years ago. The answers to eight of the questions about current conditions were compared to corresponding interview responses. The interview was considered as the "gold standard."


RESULTS
Ninety-eight percent of the subjects completed the interview without any great difficulties. According to the interview, the distributions of different exposure levels were generally positively skewed, i.e., the frequency of highly exposed subjects was low in the study base. The correlation between interview and questionnaire responses among the referents was high for time spent "sitting at work" (r = 0.82), "VDU work" (r = 0.87), and work related "motor vehicle driving" (r = 0.80). The correlation was moderate for work-related "hands above shoulder level" (rs = 0.63), and "hands below knee level (trunk flexion)" (rs = 0.66). The correlation was lower for leisure time activities such as "domestic work" (r = 0.55), "time for own activities" (r = 0.39), and "sitting during leisure time" (r = 0.38). Subjects seeking care for low back or neck/shoulder disorder estimated equally correctly or not, as had the referents. However, non-differential misclassification was present in all questions, which will attenuate observed estimates of the relative risk.


CONCLUSIONS
Even though interview data are preferable, questionnaire data may be useful for assessing well-defined work tasks and for "sitting at work."
45835042
Physical exposure assessment in monotonous repetitive work--the PRIM study.
OBJECTIVES
A program called the Project on Research and Intervention in Monotonous Work (PRIM) was initiated in 1994 as a prospective cohort study of work-related musculoskeletal disorders. The group-based exposure assessment strategy, focusing on task-related exposure and used to obtain baseline measures of physical exposures, is reported in this paper.


METHODS
Monotonous, repetitive worktasks were evaluated at 19 factories. Tasks with an estimated similarity in physical exposure were aggregated before 103 exposure groups were formed. Subjects from the exposure groups were randomly sampled for measurements, and task-related exposure levels were quantified by 43 single exposure items using a real-time video-based observation method that allowed computerized estimates of repetitiveness, body postures, force, and velocity. In combination with questionnaire-based data on task distribution, the duration of exposure was calculated at the individual level.


RESULTS
The video-based observational method and the large number of exposure variables enabled the establishment of detailed quantitative exposure profiles in 103 task-based exposure groups. However, methodological problems associated with the use of grouped exposure assessment were revealed. Despite efforts to optimize group homogeneity, the within-group variance was larger than the between-group variance for several shoulder postural variables.


CONCLUSIONS
A task-based exposure-assessment strategy can be successful in solving some of the main problems associated with the assessment of physical workplace exposures. The large within-group variance in exposure to nonneutral shoulder postures may eventually require individual assessment or the inclusion of groups with maximal contrast in exposure or both.
33031960
Validity of generic risk factors and the strain index for predicting nontraumatic distal upper extremity morbidity.
Nine individual generic risk factors, eight combinations of generic risk factors, the presence of any generic risk factor, and the Strain Index were evaluated for 56 jobs by 2 evaluators blinded to morbidity measures. Jobs then were assigned to dichotomous hazard classifications (problem versus safe) according to recommendations from the literature. OSHA 200 logs were used to ascertain historical evidence of distal upper extremity (DUE) morbidity, and jobs were assigned to a dichotomous morbidity classification (positive versus negative) using none versus one or more recorded cases as the criterion. Evidence of association and measures of predictive validity were evaluated by comparing hazard and morbidity classifications using 2 x 2 contingency tables. Five individual generic risk factors, three generic risk factor combinations, and the presence of any generic risk factor were not associated with morbidity classification. The odds ratio estimates among the four individual generic risk factors and the five combinations of generic risk factors associated with DUE morbidity varied from 3.3-36.0. The Strain Index had the largest estimated odds ratio of any exposure factor at 108.3. The exposure methods were grouped according to patterns of predictive validity. With one exception, the individual generic risk factors and their combinations had high sensitivity with low specificity (many false-positives), low sensitivity with high specificity (many false-negatives), or low sensitivity with low specificity. The only generic risk factor that demonstrated reasonable predictive validity was the use of gloves--its sensitivity, specificity, positive predictive value, and negative predictive value were equal to 0.75. The Strain Index performed better than any of the individual or combinations of generic risk factors. Its sensitivity, specificity, positive predictive value, and negative predictive value were all approximately 0.90.
17807979
Can we rely on retrospective pain assessments?
The objective of this paper was to study whether subjects in a workplace setting are able to assess the intensity of musculoskeletal pain retrospectively for a period of 3 months. The intensity of average pain and maximum pain in eight anatomic regions was assessed on a numeric rating scale. The results of 12 consecutive weekly pain recordings were compared with a final retrospective assessment of pain intensity covering the same 3-month period (119 subjects). The degree of agreement was good or excellent. The subjects were able to distinguish between the worst complaints and average complaints, and the subjective perception of aggravations or improvements corresponded to the direction of a change in score. Current complaint status slightly influenced the memory of pain. The reproducibility of the questionnaire was also assessed and showed kappa coefficients between 0.44 and 0.91 (36 subjects). The results suggest that subjects are able to accurately recall and rate the severity of pain or discomfort for a period of 3 months. These findings are of practical importance in epidemiologic studies, because they imply that retrospective reports on pain intensity are sufficiently reliable.
17676214
Implementation of neck/shoulder exercises for pain relief among industrial workers: A randomized controlled trial
BackgroundAlthough leisure-time physical activity is important for health, adherence to regular exercise is challenging for many adults. The workplace may provide an optimal setting to reach a large proportion of the adult population needing regular physical exercise. This study evaluates the effect of implementing strength training at the workplace on non-specific neck and shoulder pain among industrial workers.MethodsCluster-randomized controlled trial involving 537 adults from occupations with high prevalence of neck and shoulder pain (industrial production units). Participants were randomized to 20 weeks of high-intensity strength training for the neck and shoulders three times a week (n = 282) or a control group receiving advice to stay physically active (n = 255). The strength training program followed principles of progressive overload and periodization. The primary outcome was changes in self-reported neck and shoulder pain intensity (scale 0-9).Results85% of the participants followed the strength training program on a weekly basis. In the training group compared with the control group, neck pain intensity decreased significantly (-0.6, 95% CI -1.0 to -0.1) and shoulder pain intensity tended to decrease (-0.2, 95% CI -0.5 to 0.1, P = 0.07). For pain-cases at baseline (pain intensity > = 3) the odds ratio - in the training group compared with the control group - for being a non-case at follow-up (pain intensity < 3) was 2.0 (95% CI 1.0 to 4.2) for the neck and 3.9 (95% CI 1.7 to 9.4) for the shoulders.ConclusionHigh-intensity strength training relying on principles of progressive overload can be successfully implemented at industrial workplaces, and results in significant reductions of neck and shoulder pain.Trial registrationNCT01071980.