Hand osteoarthritis and pinch grip strength among middle-aged female dentists and teachers.

OBJECTIVES: Among female dentists and teachers, we investigated the relationship of pinch grip strength with radiographic hand osteoarthritis (OA) and hand joint pain. MATERIALS AND METHODS: We studied 295 female dentists and 248 female teachers aged 45-63 years for pinch grip strength using the Martin Vigorimeter. Hand radiographs were examined for the presence of OA in the wrist and each joint of the first, second, and third fingers. Joint pain and tasks with high hand loading during leisure were assessed by questionnaire. Glove size was used as proxy for hand size. RESULTS: Symptomatic hand OA (jointwise co-occurrence of radiological findings and pain) increased the risk of low pinch grip strength in both hands, with an odds ratio (OR) of 3.3 (95% CI 1.8-6.2) for the right and 2.0 (95% CI 1.1-3.8) for the left hand, allowing for age, occupation, body mass index (BMI), hand size, and hand-loading leisure-time activity. The occurrence of findings and pain in non-corresponding joints was also associated with pinch grip strength in the right hand, but not in the left. Having only radiographic findings or pain was not associated with pinch grip strength. CONCLUSIONS: Our findings support the view that hand function is related to the severity of hand OA.

Prospective study on shoulder symptoms among kitchen workers in relation to self-perceived and observed work load.

OBJECTIVES: To study the occurrence of shoulder symptoms among professional kitchen workers, and whether reduction in self-perceived and observed physical work load decreases future symptoms. METHODS: In this prospective study conducted in 2002-2005 in municipal kitchens in Finland, changes during a 1-year follow-up in the physical strenuousness of work tasks were self-assessed by 376 female workers (substudy I). Changes in exposure to manual lifting and awkward upper arm posture during the follow-up were also observed by experts in 69 kitchens with 183 workers (substudy II). Information on shoulder symptoms was collected with questionnaires at baseline and at follow-up. The risk of shoulder symptoms at follow-up related to changes in exposure was estimated with logistic regression. RESULTS: The 3-month prevalence of shoulder pain was 34% at baseline and 41% at follow-up. Reduction during follow-up in work tasks perceived as the most strenuous physically (ie, receiving and storing raw food) led to a significantly reduced risk of future shoulder pain with an adjusted odds ratio (OR) of 0.41 (95% CI 0.17 to 0.98) and trouble caused by the pain with an OR of 0.34 (0.14 to 0.83). The observed reduction in lifting was also associated with a lower risk for future shoulder symptoms. CONCLUSIONS: Reduction in lifting showed beneficial protective effects on the shoulder. Although more risk factor and intervention studies are needed to estimate the health impacts of kitchen work, special attention should be paid to work tasks that include lifting when assessing risk and designing preventive measures.

COL2A1 gene polymorphisms and susceptibility to osteoarthritis of the hand in Finnish women.

OBJECTIVES: To study the role of two COL2A1 single nucleotide polymorphisms (rs3737548 and rs2276455) and their haplotypes in individual susceptibility to osteoarthritis (OA) of the hand in Finnish women. METHODS: Bilateral hand radiographs of 543 Finnish female dentists and teachers aged 45-63 years were examined and classified for the presence of OA by using reference images. The COL2A1 genotypes were determined by PCR-based methods. Data regarding other risk factors were collected by questionnaire. The haplotypes were statistically reconstructed from the genotype data by the PHASE program. Associations between the genotypes/diplotypes and hand OA were studied by logistic regression. RESULTS: Allowing for age and occupation, the carriage of at least one COL2A1 intron 33 minor allele was associated with an increased risk of hand OA (odds ratio (OR) 1.58, 95% CI 1.05 to 2.36) and the number of affected joints. When stratified by occupation, the increased risk associated with the intron 33 minor allele carriage appeared to be mainly attributable to the dentists (OR 2.18, 95% CI 1.18 to 4.06). The 2-1 haplotype (exon 5B minor allele-intron 33 major allele) posed a significantly higher risk of hand OA (OR 3.21, 95% CI 1.08 to 9.55) compared with non-carriers. Moreover, an interaction was observed between intron 33 minor allele carriage and low task variation history in dental work (OR 2.87, 95% CI 1.05 to 7.89 for their joint effect). CONCLUSIONS: The results suggest that the studied COL2A1 gene polymorphisms may play a role in the aetiology of hand OA and that this effect may be enhanced by repetitive loading work tasks.

A randomised controlled trial on whether a participatory ergonomics intervention could prevent musculoskeletal disorders.

OBJECTIVES: To examine the efficacy of a participatory ergonomics intervention in preventing musculoskeletal disorders among kitchen workers. Participatory ergonomics is commonly recommended to reduce musculoskeletal disorders, but evidence for its effectiveness is sparse. METHODS: A cluster randomised controlled trial among the 504 workers of 119 kitchens in Finland was conducted during 2002-2005. Kitchens were randomised to an intervention (n = 59) and control (n = 60) group. The duration of the intervention that guided the workers to identify strenuous work tasks and to seek solutions for decreasing physical and mental workload, was 11 to 14 months. In total, 402 ergonomic changes were implemented. The main outcome measures were the occurrence of and trouble caused by musculoskeletal pain in seven anatomical sites, local fatigue after work, and sick leave due to musculoskeletal disorders. Individual level data were collected by a questionnaire at baseline and every 3 months during the intervention and 1-year follow-up period. All response rates exceeded 92%. RESULTS: No systematic differences in any outcome variable were found between the intervention and control groups during the intervention or during the 1-year follow-up. CONCLUSIONS: The intervention did not reduce perceived physical work load and no evidence was found for the efficacy of the intervention in preventing musculoskeletal disorders among kitchen workers. It may be that a more comprehensive redesign of work organisation and processes is needed, taking more account of workers' physical and mental resources.

Manual material handling advice and assistive devices for preventing and treating back pain in workers.

BACKGROUND: Training and assistive devices are considered major interventions to prevent back pain among workers exposed to manual material handling (MMH). OBJECTIVES: To determine the effectiveness of MMH advice and training and the provision of assistive devices in preventing and treating back pain. SEARCH STRATEGY: We searched MEDLINE to November 2005, EMBASE to August 2005, and CENTRAL, the Back Group's Trials Register, CINAHL, Nioshtic, CISdoc, Science Citation Index, and PsychLIT to September 2005. SELECTION CRITERIA: We included randomized controlled trials (RCT) and cohort studies with a concurrent control group, aimed at changing human behaviour in MMH and measuring back pain, back pain-related disability or sickness absence. DATA COLLECTION AND ANALYSIS: Two authors independently extracted the data and assessed the methodological quality using the criteria recommended by the Back Review Group for RCTs and MINORS for the cohort studies. One author of an original study supplied additional data for the review. The results and conclusions are based on the primary analysis of RCTs. We conducted a secondary analysis with cohort studies. We compared and contrasted the conclusions from the primary and secondary analyses. MAIN RESULTS: We included six RCTs (17,720 employees) and five cohort studies (772 employees). All studies focused on prevention of back pain. Two RCTs and all cohort studies met the majority of the quality criteria and were labeled high quality. We summarized the strength of the evidence with a qualitative analysis since the lack of data precluded a statistical analysis. There is moderate evidence that MMH advice and training are no more effective at preventing back pain or back pain-related disability than no intervention (four studies) or minor advice (one study). There is limited evidence that MMH advice and training are no more effective than physical exercise or back belt use in preventing back pain (three studies), and that MMH advice plus assistive devices are not more effective than MMH advice alone (one study) or no intervention (one study) in preventing back pain or related disability. The results of the cohort studies were similar to the randomised studies. AUTHORS' CONCLUSIONS: There is limited to moderate evidence that MMH advice and training with or without assistive devices do not prevent back pain, back pain-related disability or reduce sick leave when compared to no intervention or alternative interventions. There is no evidence available for the effectiveness of MMH advice and training or MMH assistive devices for treating back pain.

Neck muscle training in the treatment of chronic neck pain: a three-year follow-up study.

AIM: The objective of the trial was to evaluate whether the positive results achieved with a one-year training regimen in patients with chronic nonspecific neck pain would have long-standing effects. METHODS: A follow-up study of two neck muscle training groups after a randomized controlled study was carried out. One-hundred and eighteen women included were those who had performed neck strength and endurance exercises in a previous randomised controlled trial. The primary outcome measures were neck pain measured by the visual analogue scale and disability indices. Isometric neck strength, range of motion (ROM) and pressure pain threshold (PPT) were measured and training frequency for the previous month elicited by a questionnaire. RESULTS: At the 3-year follow-up, neck pain and the disability indices showed no statistically discernible change compared to the situation at the 12-month follow-up. Also, gains in neck strength, ROM and PPT achieved during the training year were largely maintained. However, adherence to the specific home training program faltered considerably. CONCLUSION: The improvements achieved through long-term training were maintained at the 3-year follow-up. Since a 12-month exercise programme shows a long-term effect, exercise may not need to be performed regularly for the remainder of the subject's life.

Finger osteoarthritis and differences in dental work tasks.

Mechanical load has been proposed as a risk factor for hand osteoarthritis. Dentists produce high manual forces in their work tasks. We studied whether the pattern of dental work tasks was associated with finger osteoarthritis. Radiographs of both hands of 291 middle-aged female dentists were examined for the presence of osteoarthritis. Patterns of dental work tasks during work history were empirically defined by cluster analysis. Three patterns emerged reflecting high, moderate, and mild task variation. Age, specialization, years in clinical work, various activities requiring hand use, family history of Heberden's nodes, body mass index, and smoking were accounted for in logistic regression analyses. The dentists with a history of low task variation had a greater prevalence of osteoarthritis in the thumb, index, and middle fingers compared with dentists with high variation (OR 2.22; 95%CI 1.04-4.91). The pattern of dental work task history is associated with the localization of osteoarthritis in the fingers.

Physical exercise and musculoskeletal pain among forest industry workers.

The study investigated the relations between physical exercise and musculoskeletal pain among forest industry workers. We studied a population of 3312 Finnish forest industry workers, who replied to a questionnaire survey in 1994 (response rate 77%). The outcome variables in this cross-sectional study were the number of days with pain in the low back, neck, shoulder and knee during the preceding 12 months. Multivariable logistic regression models were used in statistical analyses. Active walkers had more sciatic pain, active volleyball players had more shoulder pain and those who practiced trekking actively had more knee pain than those who practiced these activities less. The risk of shoulder pain was more than three times higher for those who played volleyball actively compared to those who played less. In addition, age, mental stress and work-related physical loading were strongly associated with musculoskeletal pain. When studying the relations between physical exercise and musculoskeletal pain in a working population, it is important to not only detect the general physical activity but also to specify the different modes of exercise. In addition, the other factors which are strongly related to pain (such as mental stress and work-related physical loading) should be taken into account.

A prospective study of work related factors and physical exercise as predictors of shoulder pain.

OBJECTIVES: To evaluate the effects of work related and individual factors as well as physical activity and sports on the incidence and persistence of shoulder pain among forestry workers. METHODS: Workers in a large Finnish forestry company replied to a questionnaire (a modified version of the Nordic questionnaire) on musculoskeletal pain and its possible risk factors for 4 consecutive years 1992-5. This 1 year follow up study covers the time 1994-5. Year 1994 was chosen as baseline because in that year the questionnaire contained for the first time more detailed questions about different sports. The response rate in 1995 was 90%. The effects of the predictors on 1 year incidence and persistence of shoulder pain were studied with multivariate logistic regression modelling. RESULTS: At baseline, 2094 subjects had been free of shoulder pain during the preceding 12 months. After 1 year, 14% (n=285) reported having mild or severe shoulder pain. Higher age, obesity, and mental stress as well as physically strenuous work and working with trunk forward flexed or with a hand above shoulder level increased the risk of incident shoulder pain. Of the different sports activities, dancing increased the risk of incident pain whereas jogging decreased the risk significantly. Of those 419 workers who had severe shoulder pain at baseline, 55% (n=230) still had severe pain 1 year later. Higher age, overload at work, and working with a hand above shoulder level increased the risk of persistent severe shoulder pain whereas cross country skiing and general sports activity decreased the risk. CONCLUSION: Our results support the current view that shoulder pain is the result of many factors, including occupational and individual factors. In this longitudinal study, physical work with a heavy load, awkward work postures, mental stress, and obesity were the risk factors at which preventive measures could be aimed. As a new finding, physical exercise had more protective than impairing effects on the shoulders.

A dynamic model of the forearm including fatigue.

A biomechanical model of the forearm, consisting of 61 muscle-tendon systems or tendons and 8 sections, is presented. The model can be used to calculate the muscle forces when resultant of the external forces and the motion is known. Calculations are based on constraints of muscle forces, joint forces, contact forces, and tendon junctions, and a load sharing principle telling which of the feasible solutions are likely and which are not. Fatigue is accounted for by updating the upper limits of the muscle forces according to the loading history. As an example, the model is used to predict the load sharing between the fingers when they are pressed against a table with a given total force.

Longitudinal study on work related and individual risk factors affecting radiating neck pain.

OBJECTIVES: To study the effects of work related and individual factors affecting radiating neck pain. METHODS: A longitudinal study was carried out with repeated measurements. A total of 5180 Finnish forest industry workers replied to a questionnaire survey in 1992 (response rate 75%). Response rates to follow up questionnaires in 1993, 1994, and 1995 were 83%, 77%, and 90%, respectively. The outcome variable was the number of days with radiating neck pain during the preceding 12 months with three levels (<8, 8-30, >30 days). The generalised estimating equations method was used to fit a marginal model and a transition model was used in a predictive analysis. RESULTS: Items showing associations with radiating neck pain in both analyses were sex, age, body mass index, smoking, duration of work with a hand above shoulder level, mental stress, and other musculoskeletal pains. In the transition model, radiating neck pain in a previous questionnaire was included in the model. Although it was a strong predictor, the variables already mentioned retained their significance. CONCLUSION: Programmes targeted to reduce physical load at work, mental stress, being overweight, and smoking could potentially prevent radiating neck pain.

"A good future for deaf children": a five-year sign language intervention project.

Deaf preschoolers and hearing family members learned sign language in a 5-year intervention project. Once weekly, each child met with a teacher who was deaf. Parents, siblings, and other relatives met about once monthly to study sign language, and all families in the project signed together about twice yearly. The present study addressed four questions asked of parents about the project: (a) How did the children learn to sign? (b) Did both the parents and the children benefit from the project? (c) What was the position of sign language in the family? (d) Did the project have some impact on the family's social network? The families indicated satisfaction with the project; they learned to sign and their social networks expanded. Parents favored bilingual education: Sign language was the main language but learning Finnish was also important. Learning sign language was not easy, especially for the fathers. The families that were most actively involved in the lessons learned the most.

Effects of two ergonomic aids on the usability of an in-line screwdriver.

We assessed the effects of two ergonomic aids on the usability of an in-line screwdriver. The simple aids considered were a hand support and a sleeve which softened the handle. In an experiment, 15 subjects drove screws into horizontal plywood plates with four combinations of a screwdriver and an ergonomic aid. The activities of four forearm muscles (EMG) and the force acting on the screw were measured. The subjects rated the properties of the tools as regards physical exertion, the ease of taking hold of the tool, comfort of the grip, and the surface texture. The hand support and the sleeve had positive effects on the subjective perception of exertion and the surface texture, respectively. Differences in EMG and thrust force along the shaft of the screwdriver handle were found to be too small for reliable deductions in the effects of the ergonomic aids.

Do functional tests predict low back pain?

STUDY DESIGN: A cohort of 307 nonsymptomatic workers and another cohort of 123 workers with previous episodes of low back pain were followed up for 2 years. The outcomes were measured by symptoms, medical consultations, and sick leaves due to low back disorders. OBJECTIVES: To study the predictive value of a set of tests measuring the physical performance of the back in a working population. The hypothesis was that subjects with poor functional capacity are liable to back disorders. SUMMARY OF BACKGROUND DATA: Reduced functional performance has been associated with back pain. There are few data to show whether reduced functional capacity is a cause or a consequence of pain. METHODS: Mobility of the trunk in forward and side bending, maximal isokinetic trunk extension, flexion and lifting strength, and static endurance of back extension were measured. Standing balance and foot reaction time were recorded with a force plate. Clinical tests for the provocation of back or leg pain were performed. Gender, workload, age, and anthropometrics were managed as potential confounders in the analysis. RESULTS: Marked overlapping was seen in the measures of the subjects with different outcomes. Among the nonsymptomatic subjects, low performance in tests of mobility and standing balance was associated with future back disorders. Among workers with previous episodes of back pain, low isokinetic extension strength, poor standing balance, and positive clinical signs predicted future pain. CONCLUSIONS: Some associations were found between the functional tests and future low back pain. The wide variation in the results questions the value of the tests in health examinations (e.g., in screening or surveillance of low back disorders).

Assessment of duration and frequency of work tasks by telephone interview: reproducibility and validity.

Quantitative estimation of physical work load requires breakdown of jobs into smaller entities. The objective was to study the inter-rater reproducibility of the contents, frequency and duration of work tasks assessed by telephone interview. Two researchers interviewed 18 industrial workers with an interval of from 2 to 3 weeks in a balanced and blinded design. Altogether 114 tasks were identified, 68 of which were recorded by both interviewers. The tasks were classified into regularly occurring (n = 34) and occasional (n = 80). The outcome was the total duration of the tasks per day computed from the data on frequency and duration. Validity of the interview was studied against prestructured diaries filled in by nine workers. The interviewers' assessments of the overall contents of the tasks were rated as 'similar' or 'very similar' for 17 of the 18 workers. Both interviewers detected all 34 regularly occurring tasks. The intraclass correlation coefficient (ICC) of the total duration between the interviewers was 0.81 for regularly occurring tasks. ICCs of the total duration between the diary and the two interviewers were 0.90 and 0.91. However, in many cases the workers could not give a numerical value for duration or frequency. A telephone interview can be used as a first step in exposure assessment in epidemiological studies on risk factors of musculoskeletal disorders. These results show that a single telephone interview can give reproducible and valid information of the frequency and duration of tasks occurring daily. For occasional tasks interview methods should be developed further.

Active treatment of chronic neck pain: a prospective randomized intervention.

STUDY DESIGN: A randomized comparative study with single-blind outcome assessments. OBJECTIVES: To compare the efficacy of a multimodal treatment emphasizing proprioceptive training (ACTIVE) with activated home exercises (HOME) and recommendation of exercise (CONTROL) in patients with nonspecific chronic neck pain. SUMMARY OF BACKGROUND DATA: The efficacy of active exercises and passive physiotherapy for neck trouble has been somewhat disappointing in the previous few studies. METHODS: Seventy-six patients (22 men, 54 women) with chronic, nonspecific neck pain participated. Sixty-two participated the 1-year follow-up. Subjective pain and disability, cervical ranges of motion, and pressure pain threshold in the shoulder region were measured at baseline, at 3 months, and at 12 months. The ACTIVE treatment consisted of 24 sessions of proprioceptive exercises, relaxation, and behavioral support. The HOME regimen included a neck lecture and two sessions of practical training for home exercises and instructions for maintaining a diary of progress. The CONTROL treatment included a lecture regarding care of the neck with a recommendation to exercise. RESULTS: The average self-experienced total benefit was highest in the ACTIVE group, and the HOME group rated over the CONTROL group (P < 0.001). Differences between the groups in favor of the ACTIVE treatment were recorded in reduction of neck symptoms and improvements in general health and self-experienced working ability (P < 0.01-0.03). Changes in measures of mobility and pressure pain threshold were minor. CONCLUSIONS: Regarding self-experienced benefit, the multimodal treatment was more efficacious than activated home exercises that were clearly more efficacious than just advising. No major differences were noted in objective measurements of cervical function between the groups, but the content validity of these assessments in chronic neck trouble can be questioned.

Do psychological factors predict changes in musculoskeletal pain? A prospective, two-year follow-up study of a working population.

Our aim was to determine the predictive value of some psychometric instruments for the development and persistence of musculoskeletal pain. In 452 subjects, pain in the shoulder, neck, and low back during the preceding year was assessed at baseline, one year, and two years' follow-up. Psychological distress, depression, self-efficacy beliefs, subjective work prognosis, disability, and work characteristics were assessed at baseline. The best predictor of future pain was disability. The psychometric measures did not predict changes in pain. The explanatory power of the variables in the multivariate analyses was low. Perceived disability in persons with musculoskeletal symptoms should be acknowledged early. The traditional research paradigm focusing on a few hypothetically relevant variables does not take into account the reflective, dynamic, reciprocal nature of human behavior during the process of recovery from or development of a pain problem.

Standardized physical examination protocol for low back disorders: feasibility of use and validity of symptoms and signs.

A standardized examination protocol was developed for the assessment of low back disorders in primary care. The protocol was found feasible in the occupational health service setting. The interexaminer repeatability between an occupational physician and an occupational physiotherapist was good for most items. The predictive validity of different symptoms and signs was investigated with regard to future sick leaves due to low back disorders. Relief of pain when lying, severe trouble at work caused by pain, continuous pain, and pain in the leg or numbness or diminished sensitivity in the foot predicted sick leaves. Of physical signs, pain in the low back or buttock during lateral flexion and a side difference > or = 20 degrees in the straight-leg-raising angle were predictors for sick leaves. The predictive validity of the protocol items should be tested in another patient population before conclusions can be drawn concerning the external validity of our results.

Validation of Portable Ergonomic Observation (PEO) method using optoelectronic and video recordings.

The validity of the 'Portable Ergonomic Observation' method (PEO) was investigated against posture measurements based on continuous optoelectronic and video recordings made simultaneously with the observation. Work postures and actions during different frequently changing tasks were analyzed using both methods. In general, a high agreement between measured and observed data was achieved for the duration of clearly identifiable sustained postures and actions (such as repetitive movements of hands when typing), as well as for the frequency of clearly distinguishable actions (such as lifts). The agreement between observations and measurements was low for neck postures. In dynamic tasks the agreement was generally low. This was probably because of high levels of simultaneous information for the observer. No improvement in the agreement between measured and observed events could be achieved by leaving parts of the PEO categories unobserved at a time. Playback of video tapes to observe each category separately would increase the reliability of the observations but at the expense of increased time for the analysis.