Radiographic findings in patients suspected of subacromial impingement syndrome: prevalence and reliability.

OBJECTIVE: Aims were to (i) report prevalence and (ii) evaluate reliability of the radiographic findings in examinations of patients suspected of subacromial impingement syndrome (SIS), performed before a patient's first consultation at orthopaedic department. MATERIALS AND METHODS: This cross-sectional study examined radiographs from 850 patients, age 18 to 63 years, referred to orthopaedic clinic on suspicion of SIS. Prevalence (%) of radiographic findings were registered. Inter- and intrarater reliability was analysed using expected and observed agreement (%), kappa coefficients, Bland-Altman plots, or intraclass coefficients. RESULTS: A total of 850 patients with a mean age of 48.2 years (SD = 8.8) were included. Prevalence of the radiographic findings was as follows: calcification 24.4%, Bigliani type III (hooked) acromion 15.8%, lateral/medial acromial spurs 11.1%/6.6%, acromioclavicular osteoarthritis 12.0%, and Bankart/Hill-Sachs lesions 7.1%. Inter- and intrarater Kappa values for most radiographic findings ranged between 0.40 and 0.89; highest values for the presence of calcification (0.85 and 0.89) and acromion type (0.63 and 0.66). The inter- and intrarater intraclass coefficients ranged between 0.41 and 0.83; highest values for acromial tilt (0.79 and 0.83) and calcification area (0.69 and 0.81). CONCLUSION: Calcification, Bigliani type III (hooked) acromion, and acromioclavicular osteoarthritis were prevalent findings among patients seen in orthopaedic departments on suspicion of SIS. Spurs and Bankart/Hill-Sachs lesions were less common. Optimal reliabilities were found for the presence of calcification, calcification area, and acromial tilt. Calcification qualities, acromion type, lateral spur, and acromioclavicular osteoarthritis showed suboptimal reliabilities. Newer architectural measures (acromion index and lateral acromial angle) performed well with respect to reliability.

Return to Work After Surgery For Trapeziometacarpal Joint Osteoarthritis in Relation to Occupational Hand Force Requirements.

PURPOSE: This study evaluated the hypothesis that higher occupational hand force requirements are related to slower return to work (RTW) after surgery for trapeziometacarpal joint osteoarthritis. METHODS: Patients treated surgically for trapeziometacarpal joint osteoarthritis from 2001 to 2017 were identified in the Danish National Patient Register. Sustainable RTW (sRTW) was defined as the first period of 4 consecutive weeks without health-related public transfer payments, according to the Danish National Register on Public Transfer Payments. Occupational codes from the Danish Employment Classification Module were linked to a hand-arm job exposure matrix to obtain occupational hand force requirements for each patient. Cox regression models were used to analyze time until sRTW in relation to hand force requirements with adjustment for age, sex, type of surgery, preoperative sick leave, and calendar year of surgery. RESULTS: The study included 2,090 patients. Within 104 weeks, 91% sustainably returned to work. The percentage of individuals in the subgroups that did not RTW was 8% of low-force- and medium-force-exposed patients and 14% of high-force-exposed patients. Medium and high occupational hand force requirements were associated with slower sRTW. The adjusted hazard ratio for sRTW was 0.84 (95% confidence interval, 0.74-0.95) for medium and 0.59 (95% confidence interval, 0.50-0.68) for high compared with low hand force requirements. Among patients who returned to work, patients with medium and high hand force requirements had median periods until sRTW of 16 and 18 weeks, respectively, compared with 10 weeks among patients with low hand force requirements. CONCLUSIONS: The prognosis regarding RTW after surgery for trapeziometacarpal joint osteoarthritis is generally good, but patients with higher occupational hand force requirements can expect slower RTW. TYPE OF STUDY/LEVEL OF EVIDENCE: Prognostic II.

Increased shoulder pain across an exercise session and subsequent shoulder exercise: a prospective cohort study.

BACKGROUND: Shoulder complaints are common and the recommended first-line treatment is exercise therapy. However, it remains unknown if increased shoulder pain after an exercise session is a barrier for subsequent exercise dose, particularly in people with high fear-avoidance beliefs. Such knowledge could indicate ways to optimise shoulder rehabilitation. The aim was to examine whether increased shoulder pain across an exercise session was associated with a lower subsequent exercise dose, and if high fear-avoidance beliefs exaggerated this association. METHODS: We conducted a prospective cohort study using data from a randomised controlled trial in Central Denmark Region 2017-2019. Participants were employees (n = 79) with shoulder complaints and high occupational shoulder exposures. The intervention was a home-based or partly supervised exercise programme lasting 2-3 months. Linear mixed models were used to examine the associations between change in shoulder pain and exercise dose (number of repetitions, progression level (1-3), resistance level (1-3), and time until next exercise session [days]). RESULTS: At baseline, the participants had a median pain intensity at rest of 2 on a numerical rating scale (0-10). For a 1-cm increase in pain on a visual analogue scale (0-10 cm) during an exercise session, the subsequent number of repetitions, progression level and resistance level were - 1.3 (95% confidence interval [CI] - 3.4 to 0.9), 0.0 (95% CI - 0.1 to 0.0) and - 0.0 (95% CI - 0.1 to 0.0), respectively. Likewise, the time until next exercise session was - 0.6 (95% CI - 2.4 to 1.3) days for a 1-cm increase. There were no interactions with fear-avoidance beliefs. CONCLUSION: Increased pain across an exercise session was not associated with subsequent exercise dose, regardless of fear-avoidance beliefs, among employees with shoulder complaints and high occupational shoulder exposures. TRIAL REGISTRATION: The trial was registered at Clinicaltrials.gov 19/05/2017 (ID: NCT03159910).

Surgery for trapeziometacarpal osteoarthritis in relation to cumulative occupational hand force requirements: a Danish nationwide cohort study.

OBJECTIVES: To evaluate if higher cumulative occupational hand force requirements are associated with higher risks of surgery for trapeziometacarpal osteoarthritis and with surgery earlier in life. METHODS: The study was based on Danish national registers. Among all persons born in Denmark 1931 to 1990, we included those who had been employed for at least 5 years since 1991 by the end of 2000, or later when this employment criterion was reached, up until the end of 2016. Cumulative exposure estimates for 10-year time windows (force-years) were assessed by combining individual year-by-year information on occupational codes with an expert based hand-arm job exposure matrix. First-time events of surgery for trapeziometacarpal osteoarthritis 2001 to 2017 constituted the outcome. Surgery rates were analysed by a logistic regression technique equivalent to discrete survival analysis using a 1-year lag. We also calculated rate advancement periods. RESULTS: A total of 2 860 448 persons contributed with around 48 million person-years of follow-up, during which 3977 cases appeared (821 among men and 3156 among women). Compared with <5 force-years, the adjusted OR (ORadj) for ≥5 to <10 force-years was 1.39 (95% CI 1.14 to 1.68) and for ≥10 to 30 force-years 1.47 (95% CI 1.26 to 1.71) among men and 1.64 (95% CI 1.50 to 1.78) and 1.29 (95% CI 1.16 to 1.43) among women. The sex combined ORadj were 1.59 (95% CI 1.47 to 1.72) and 1.36 (95% CI 1.25 to 1.48). Among the exposed, surgery was advanced by 3 to 7 years. CONCLUSION: Medium/high cumulative hand force requirements were associated with elevated hazard rates of surgery for trapeziometacarpal osteoarthritis and advanced the time of surgery by several years.

Influence of Occupational Hand Force Requirements on Return to Work, Pain, and Disability After Trapeziometacarpal Total Joint Arthroplasty: A 12-Month Follow-Up Study.

PURPOSE: We aimed to determine the prognosis after trapeziometacarpal total joint arthroplasty for basal thumb osteoarthritis with respect to sustainable return to work (RTW), pain, and disability. Our main hypothesis was that high occupational hand force requirements are related to slower RTW. METHODS: We conducted a 12-month follow-up study of patients who were treated with a trapeziometacarpal total joint arthroplasty in 2003 to 2015 and were active in the labor market at the time of surgery. We used registry information about RTW. Before surgery and at the 12-month follow-up, we obtained data on pain and disability. To obtain estimates of occupational hand force requirements for individual patients, we linked the patients' self-reported job title to a job exposure matrix based on experts' ratings. We used Cox regression models to analyze the time until sustainable RTW and logistic regression models to analyze pain and disability. RESULTS: A total of 133 patients were included. Most patients returned to work within 12 months after surgery (86%). For those who returned to work within 12 months (n = 114), mean time until sustainable RTW was 14 weeks (SD, 9 weeks). Higher hand force requirements were associated with slower RTW (for medium- and high-force requirements, adjusted hazard ratios were 0.48 [95% confidence interval, 0.30-0.78] and 0.41 [95% confidence interval, 0.25-0.69]). Occupational hand force requirements were not associated with pain and disability at follow-up. CONCLUSIONS: High occupational hand force requirements were associated with slower RTW, but not with pain and disability 12 months after surgery. TYPE OF STUDY/LEVEL OF EVIDENCE: Prognostic I.

Exposure-response relationships between cumulative occupational shoulder exposures and different diagnoses related to surgery for subacromial impingement syndrome.

PURPOSE: The aim was to examine associations between cumulative occupational shoulder exposures and different diagnoses related to surgery for subacromial impingement syndrome (SIS). METHODS: We re-analysed data from a previous register-based cohort study of the Danish working population (2,374,403 persons) with follow-up 2003-2008. The outcomes were eight different SIS-related diagnosis codes (M19, M75.1-5, and M75.8-9) in combination with SIS-related surgery codes. Occupational shoulder exposures were estimated by combining occupational codes with an expert-rated job exposure matrix. Cumulative exposure estimates were calculated for 10-year time windows and expressed as exposure-years. We used a logistic regression technique equivalent to discrete survival analysis. RESULTS: Exposure-response relationships were found between most occupational shoulder exposures and the different SIS-related diagnosis codes. For arm-elevation-years, M19, M75.1, and M75.4 reached maximum adjusted odds ratio (ORadj) of 2.0-2.4, while the maximum ORadj for M75.3 was 1.6; we found intermediate values for the remaining diagnoses. The relationships were almost similar for repetition-years and shoulder-load-years. For force-years, maximum ORadj of 1.7-1.9 was seen for M19, M75.1, and M75.4, while M75.3 reached a maximum ORadj of 1.3. For HAV-years, M19, M75.1, and M75.4 reached maximum ORadj of 1.5-1.7, while M75.3 reached a maximum ORadj of 1.1. CONCLUSION: We found associations between all occupational shoulder exposures and the eight different SIS-related diagnoses; exposure-response relationships were found for most diagnoses. The highest risks were seen for M19 (acromioclavicular osteoarthritis), M75.1 (rotator cuff syndrome), and M75.4 (impingement syndrome), and the lowest for M75.3 (calcific tendinitis).

Persistent postoperative pain after inguinal hernia repair in relation to occupational lifting and standing/walking: a 6-month follow-up study.

OBJECTIVES: This study aims to evaluate the risk of persistent postoperative pain after inguinal hernia repair in relation to occupational lifting and standing/walking. METHODS: We conducted a 6-month follow-up study that included all men with an inguinal hernia repair registered in the Danish Hernia Database from 1 January 2015 to 31 October 2016, who were born from 1 October 1949 to 1 October 1998, and who were alive, living in Denmark, and active in the labour market in the week before surgery. Members of the cohort received a questionnaire 6 months after surgery. Exposure estimates were allocated by combining self reported job titles with a job exposure matrix. Prevalence ratios of persistent postoperative pain during activity ≥2 on a numerical rating scale (range 0-10) according to occupational lifting and standing/walking were estimated using Poisson regression. RESULTS: Of 4817 eligible patients, 2609 (54%) returned the questionnaire and 2508 contributed to the analyses. A total of 473 men (18.9%) reported persistent postoperative pain. In the group lifting >1000 to 6125 kg/day, the prevalence was 26.8% compared with 17.5% in the minimally exposed group; adjusted prevalence ratio: 1.44 (95% CI 1.16 to 1.79). For standing/walking >6 hours/day, the prevalence was 23.6% compared with 17.0% in the group standing <4 hours/day; adjusted prevalence ratio: 1.18 (95% CI 0.92 to 1.50). CONCLUSIONS: The risk of persistent postoperative pain after inguinal hernia repair was elevated among men with occupational lifting exposures >1000 kg/day. This finding suggests a preventive potential.

Prevalence and severity of fatigue in adolescents and young adults with acquired brain injury: A nationwide study.

Objective: To investigate the prevalence and severity of fatigue in adolescents and young adults with acquired brain injury (ABI) compared with healthy controls (HCs) and to examine associations between fatigue and gender, age and level of education. Methods: This cross-sectional study included 15-30 year old patients with ABI and a convenience sample of 15-30 year old HCs. All participants completed the 20-item Multidimensional Fatigue Inventory (MFI-20). Pathological fatigue was defined as "General Fatigue" ≥12. Adjusted mean differences between groups were calculated using multivariate analysis of covariance (MANCOVA). The adjusted prevalence proportion ratio (PPRadj) of pathological fatigue was calculated using Poisson regression. Results: The patients (n = 334) had higher scores than the HCs (n = 168) on all MFI-20 subscales with adjusted mean differences ranging from 1.7 to 4.7 and a higher prevalence of pathological fatigue (73% versus 29%), PPRadj 2.7 (95% confidence interval 2.1-3.5). Female patients experienced more fatigue than males on the "General Fatigue" and "Reduced Activity" subscales, while no gender differences were found in the HC group. Patients and HCs with elementary education had elevated scores on the "Reduced Activity" and "Mental Fatigue" subscales. Age was not associated with any of the subscale scores. Conclusion: Young patients with ABI had markedly higher prevalence and severity of fatigue than HCs. Age (15-30 years) was not associated with fatigue. No clear patterns of associations were evident with gender and level of education. Abbreviations: ABI: acquired brain injury; CI: confidence interval; GF: general fatigue; GOSE: Glasgow Outcome Scale Extended; HC: healthy control; MANCOVA: multivariate analysis of covariance; MF: mental fatigue; MFI-20: Multidimensional Fatigue Inventory-20; PF: physical fatigue; RA: reduced activity; RM: reduced motivation; TBI: traumatic brain injury.

Surgery for subacromial impingement syndrome in relation to intensities of occupational mechanical exposures across 10-year exposure time windows.

OBJECTIVES: We aimed to identify intensities of occupational mechanical exposures (force, arm elevation and repetition) that do not entail an increased risk of surgery for subacromial impingement syndrome (SIS) even after prolonged durations of exposure. Additionally, we wanted to evaluate if exposure to hand-arm vibration (HAV) is an independent risk factor. METHODS: We used data from a register-based cohort study of the entire Danish working population (n=2 374 403). During follow-up (2003-2008), 14 118 first-time events of surgery for SIS occurred. For each person, we linked register-based occupational codes (1993-2007) to a general population job exposure matrix to obtain year-by-year exposure intensities on measurement scales for force, upper arm elevation >90° and repetition and expert rated intensities of exposure to HAV. For 10-year exposure time windows, we calculated the duration of exposure at specific intensities above minimal (low, medium and high). We used a logistic regression technique equivalent to discrete survival analysis adjusting for cumulative effects of other mechanical exposures. RESULTS: We found indications of safe exposure intensities for repetition (median angular velocity <45°/s), while force exertion ≥10% of maximal voluntary electrical activity and upper arm elevation >90° >2 min/day implied an increased risk reaching ORs of 1.7 and 1.5 after 10 years at low intensities. No associations were found for HAV. CONCLUSIONS: We found indications of safe exposure intensities for repetition. Any intensities of force and upper arm elevation >90° above minimal implied an increased risk across 10-year exposure time windows. No independent associations were found for HAV.

Diffusion MRI findings in patients with extensive and minimal post-concussion symptoms after mTBI and healthy controls: a cross sectional study.

PRIMARY OBJECTIVES: We hypothesized that the microstructure of the corpus callosum, thalamus and hippocampus, as measured with diffusion and Mean of the Kurtosis Tensor (MKT) MRI, differs between healthy subjects and patients with extensive and minimal post-concussion symptoms (PCS) and that MKT measures correlate with PCS severity and self-reported cognitive symptoms. RESEARCH DESIGN: A cross-sectional study comparing patients with extensive PCS and patients with minimal PCS 2-5 months after mild traumatic brain injury (mTBI) with each other and with an external healthy control group. METHODS AND PROCEDURES: Diffusion MRI was obtained in 25 patients with extensive PCS and in 25 patients with minimal PCS as measured by the Rivermead Post-concussion Symptoms Questionnaire. The patients were matched on age, sex and time since accident. Data from an external healthy control group (n = 27) was included. MAIN OUTCOME AND RESULTS: There was no difference in MKT between the two groups with mTBI and no correlation between MKT and PCS. There was no difference between the three groups in other diffusion measures. CONCLUSIONS: Our results did not point to microstructural changes in the corpus callosum, thalamus and hippocampus in relation to PCS after mTBI.

Surgery for subacromial impingement syndrome in relation to occupational exposures, lifestyle factors and diabetes mellitus: a nationwide nested case-control study.

OBJECTIVES: To estimate the risk of surgery for subacromial impingement syndrome (SIS) in relation to occupational exposures, lifestyle factors and diabetes mellitus. METHODS: We conducted a case-control study nested in a register-based cohort study of the Danish working population. For each of 3000 first-time cases of surgery for SIS, two age-matched and sex-matched controls were drawn. Cases and controls received a questionnaire on job history and other factors. Job histories were combined with a psychosocial job exposure matrix (JEM) and the updated Shoulder JEM, which provided exposure intensities on measurement scales. Ten-year cumulative exposures to upper arm elevation >90°, repetitive shoulder movements, forceful shoulder exertions and hand-arm vibrations (HAVs) were estimated. We used conditional logistic regression. RESULTS: There were 5396 persons (60%) who answered the questionnaire. For occupational mechanical exposures, the adjusted OR (ORadj) ranged from 1.9 (95% CI 1.5 to 2.5 for HAVs) to 2.5 (95% CI 1.9 to 3.5 for force) among men and 1.7 (95% CI 1.2 to 2.5 for HAVs) to 2.0 (95% CI 1.3 to 2.9 for force) among women. No statistically significant associations were found for occupational psychosocial factors. Body mass index (BMI) and pack-years of smoking showed ORadj up to 2.0. Diabetes mellitus showed ORadj of 1.5 (95% CI 1.1 to 2.2) for men and 2.2 (95% CI 1.4 to 3.4) for women. CONCLUSIONS: Our findings add to the evidence of an increased risk of surgery for SIS in relation to occupational cumulative mechanical exposures, even when an increased risk in relation to BMI, smoking and diabetes mellitus is taken into account.

Inguinal hernia repair among men in relation to occupational mechanical exposures and lifestyle factors: a longitudinal study.

OBJECTIVES: To evaluate exposure-response relationships between occupational mechanical exposures and first-time lateral and medial inguinal hernia repair and effects of lifestyle factors. To estimate if occupational mechanical exposures advance the repairs. METHODS: This longitudinal study was based on a cohort of men aged 18-65 years with questionnaire data from the Musculoskeletal Research Database at the Danish Ramazzini Centre. We estimated occupational mechanical exposures using a job exposure matrix. First-time inguinal hernia repairs from 1998 to 2014 were identified in the Danish Hernia Database. We used Cox regression analyses and calculated excess fractions among the exposed and rate advancement periods (RAPs). RESULTS: Among 17 967 men, we identified 382 lateral and 314 medial repairs. The risk of lateral repairs increased with time spent standing/walking with an HR of 1.45 (95% CI 1.12 to 1.88) for ≥6 hours/day versus <4 hours/day, corresponding to an excess fraction of cases of 31% in the group with ≥6 hours/day. This group had a RAP of 6.7 (95% CI 2.6 to 10.8) years. Medial repairs were not associated with occupational mechanical exposures. A body mass index ≥30 kg/m2 showed lower HRs for both repair types. Leisure-time physical activity and smoking status were not related to any of the outcomes. CONCLUSIONS: Assuming a causal relationship, the results suggest that around 30% of all first-time lateral inguinal hernia repairs in the highest exposure category would be preventable if the time spent standing/walking could be reduced from ≥6 to <4 hours/day. The repairs might even be postponed by 6-7 years.

Upper arm elevation and repetitive shoulder movements: a general population job exposure matrix based on expert ratings and technical measurements.

OBJECTIVES: We recently constructed a general population job exposure matrix (JEM), The Shoulder JEM, based on expert ratings. The overall aim of this study was to convert expert-rated job exposures for upper arm elevation and repetitive shoulder movements to measurement scales. METHODS: The Shoulder JEM covers all Danish occupational titles, divided into 172 job groups. For 36 of these job groups, we obtained technical measurements (inclinometry) of upper arm elevation and repetitive shoulder movements. To validate the expert-rated job exposures against the measured job exposures, we used Spearman rank correlations and the explained variance[Formula: see text] according to linear regression analyses (36 job groups). We used the linear regression equations to convert the expert-rated job exposures for all 172 job groups into predicted measured job exposures. Bland-Altman analyses were used to assess the agreement between the predicted and measured job exposures. RESULTS: The Spearman rank correlations were 0.63 for upper arm elevation and 0.64 for repetitive shoulder movements. The expert-rated job exposures explained 64% and 41% of the variance of the measured job exposures, respectively. The corresponding calibration equations were y=0.5%time+0.16×expert rating and y=27°/s+0.47×expert rating. The mean differences between predicted and measured job exposures were zero due to calibration; the 95% limits of agreement were ±2.9% time for upper arm elevation >90° and ±33°/s for repetitive shoulder movements. CONCLUSIONS: The updated Shoulder JEM can be used to present exposure-response relationships on measurement scales.

Exposure-response relationships between movements and postures of the wrist and carpal tunnel syndrome among male and female house painters: a retrospective cohort study.

OBJECTIVES: To investigate exposure-response relationships between measured movements and postures of the wrist and the incidence of carpal tunnel syndrome (CTS), and any modifications by sex. METHODS: In 2011, we established a historical cohort of 9364 members of the Painters' Union in Denmark. Self-reported task distributions were obtained by questionnaire (53% responded) and combined with sex-specific task exposure matrices to get individual estimates of exposure intensity, that is, velocity of wrist flexion/extension, mean power frequency (MPF) and non-neutral wrist postures. Exposure duration was assessed from yearly working proportions. Registered first-time hospital discharge CTS diagnoses and CTS surgery were collected as outcomes. The cohort was followed from 1994 to 2010. Log-linear Poisson regression was used. RESULTS: For CTS diagnoses, the adjusted incidence rate ratios (IRRs) increased with increasing wrist velocity (IRR=1.37 (95% CI 1.10 to 1.71) per °/s) and MPF (IRR=1.53 (95% CI 1.21 to 1.91) per 0.01 Hz). For CTS surgery, the results were similar. The outcomes were not related to non-neutral postures or exposure duration. The adjusted IRRs for women were higher than those for men. There were no multiplicative interaction effects between exposure intensity, exposure duration and sex. However, the absolute incidence rates (IRs) increased at a steeper rate for women than for men, indicating an additive interaction. CONCLUSIONS: The incidence of CTS increased with increasing velocity of wrist flexion/extension and MPF of wrist movements. The relative increase in incidence rates was the same for women and men, but the absolute incidence rates increased at a steeper rate for women than for men.

Varicose veins in the lower extremities in relation to occupational mechanical exposures: a longitudinal study.

OBJECTIVES: To evaluate if occupational mechanical exposures are associated with an increased risk of surgery for varicose veins (VV) in the lower extremities. METHODS: We conducted a longitudinal study of persons from the Musculoskeletal Research Database at the Danish Ramazzini Centre who were 18-65 years old when they provided baseline questionnaire data during 1993-2004. Exposure estimates were obtained from a job exposure matrix based on expert ratings. The register information on first-time surgery for VV was retrieved. We used Cox regression analyses. RESULTS: During 416,317 person-years of follow-up among 38,036 persons, 851 first-time operations for VV occurred. Using standing/walking <4 h/day and uncommon lifting as references, exposure-response relationships with risk of surgery were found for men. For women, the risk increased too, but without clear exposure-response patterns. The adjusted HRs for ≥6 h/day spent standing/walking were 3.17 (95% CI 2.06 to 4.89) and 2.34 (95% CI 1.72 to 3.19) for men and women, respectively. For high lifting exposures (≥1000 kg/day), the adjusted HRs were 3.95 (95% CI 2.32 to 6.73) for men and 2.54 (95% CI 1.95 to 3.31) for women. Other risk factors were increasing age for men and parity for women. Minimal leisure-time physical activity, a high body mass index and smoking were not associated with increased risk. CONCLUSIONS: The results suggested an increased risk of surgery for VV in relation to prolonged standing/walking and heavy lifting and a preventive potential of more than 60% of all cases in exposed occupations.

Combined musculoskeletal pain in the upper and lower body: associations with occupational mechanical and psychosocial exposures.

PURPOSE: Pain in more than one site is common in working populations. We aimed to characterise combined pain (pain in the upper and lower body) and to evaluate whether the prevalence of combined pain is positively related to combined occupational mechanical exposures to the upper and lower body and to high psychosocial job strain. METHODS: This cross-sectional study was based on questionnaire data from the Musculoskeletal Research Database at the Danish Ramazzini Centre. The study included 14,081 men and 20,173 women. Occupational exposures were assessed by job exposure matrices. We analysed the prevalence of pain limited to the upper body, pain limited to the lower body, and combined pain in relation to occupational exposures using Poisson regression. RESULTS: During the last year, 23.2 % of the men and 33.9 % of the women reported combined pain, which was characterised by somatisation, illness worrying, and low SF-36 scores. For men, the adjusted prevalence ratio for combined pain was 1.51 [95 % confidence interval (95 % CI) 1.40-1.64] in relation to exposures limited to the upper body and 2.24 (95 % CI 2.11-2.39) in relation to combined exposures. For women, the corresponding adjusted prevalence ratios were 1.56 (95 % CI 1.50-1.63) and 1.55 (95 % CI 1.50-1.61). High job strain was related to pain among men, only. CONCLUSION: Combined pain may in part be explained by local effects of occupational mechanical exposures acting at more than one site.

Cumulative occupational shoulder exposures and surgery for subacromial impingement syndrome: a nationwide Danish cohort study.

OBJECTIVES: The primary aim was to examine exposure-response relationships between cumulative occupational shoulder exposures and surgery for subacromial impingement syndrome (SIS), and to compare sex-specific exposure-response relationships. The secondary aim was to examine the time window of relevant exposures. METHODS: We conducted a nationwide register study of all persons born in Denmark (1933-1977), who had at least 5 years of full-time employment. In the follow-up period (2003-2008), we identified first-time events of surgery for SIS. Cumulative exposure estimates for a 10-year exposure time window with a 1-year lag time were obtained by linking occupational codes with a job exposure matrix. The exposure estimates were expressed as, for example, arm-elevation-years in accordance with the pack-year concept of tobacco consumption. We used a multivariable logistic regression technique equivalent to discrete survival analysis. RESULTS: The adjusted OR (ORadj) increased to a maximum of 2.1 for arm-elevation-years, repetition-years and force-years, and to 1.5 for hand-arm-vibration-years. Sex-specific exposure-response relationships were similar for men and women, when assessed using a relative risk scale. The ORadj increased gradually with the number of years contributing to the cumulative exposure estimates. The excess fraction was 24%. CONCLUSIONS: Cumulative occupational shoulder exposures carried an increase in risk of surgery for SIS with similar exposure-response curves for men and women. The risk of surgery for SIS increased gradually, when the period of exposure assessment was extended. In the general working population, a substantial fraction of all first-time operations for SIS could be related to occupational exposures.

Sex differences in muscular load among house painters performing identical work tasks.

PURPOSE: The present study aimed to estimate possible differences in upper body muscular load between male and female house painters performing identical work tasks. Sex-related differences in muscular load may help explain why women, in general, have more musculoskeletal complaints than men. METHODS: In a laboratory setting, 16 male and 16 female house painters performed nine standardised work tasks common to house painters. Unilateral electromyography (EMG) recordings were obtained from the supraspinatus muscle by intramuscular electrodes and from the trapezius, extensor and flexor carpi radialis muscles by surface electrodes. Relative muscular loads in %EMGmax as well as exerted force in Newton, based on ramp calibrations, were assessed. Sex differences were tested using a mixed model approach. RESULTS: Women worked at about 50% higher relative muscular loads than men in the supraspinatus and forearm muscles at all percentiles and in all tasks. Women exerted about 30% less force in the trapezius muscle at the 50th percentile. CONCLUSIONS: Female house painters had a higher relative muscular load than their male colleagues without exerting more force. The effects of a higher relative muscular load accumulated over years of work may in part explain why musculoskeletal complaints in the upper body occur more frequently among women than men.

An expert-based job exposure matrix for large scale epidemiologic studies of primary hip and knee osteoarthritis: the Lower Body JEM.

BACKGROUND: When conducting large scale epidemiologic studies, it is a challenge to obtain quantitative exposure estimates, which do not rely on self-report where estimates may be influenced by symptoms and knowledge of disease status. In this study we developed a job exposure matrix (JEM) for use in population studies of the work-relatedness of hip and knee osteoarthritis. METHODS: Based on all 2227 occupational titles in the Danish version of the International Standard Classification of Occupations (D-ISCO 88), we constructed 121 job groups comprising occupational titles with expected homogeneous exposure patterns in addition to a minimally exposed job group, which was not included in the JEM. The job groups were allocated the mean value of five experts' ratings of daily duration (hours/day) of standing/walking, kneeling/squatting, and whole-body vibration as well as total load lifted (kg/day), and frequency of lifting loads weighing ≥20 kg (times/day). Weighted kappa statistics were used to evaluate inter-rater agreement on rankings of the job groups for four of these exposures (whole-body vibration could not be evaluated due to few exposed job groups). Two external experts checked the face validity of the rankings of the mean values. RESULTS: A JEM was constructed and English ISCO codes were provided where possible. The experts' ratings showed fair to moderate agreement with respect to rankings of the job groups (mean weighted kappa values between 0.36 and 0.49). The external experts agreed on 586 of the 605 rankings. CONCLUSION: The Lower Body JEM based on experts' ratings was established. Experts agreed on rankings of the job groups, and rankings based on mean values were in accordance with the opinion of external experts.

Occupational lifting of heavy loads and preterm birth: a study within the Danish National Birth Cohort.

OBJECTIVES: To examine the association between occupational lifting during pregnancy and preterm birth. The risk of preterm birth was estimated for total burden lifted per day and number of medium and heavy loads lifted per day. METHODS: In a study population of 62 803 pregnant women enrolled to the Danish National Birth Cohort from 1996 to 2002, the association between self-reported occupational lifting in the first part of pregnancy and preterm birth was analysed using logistic regression models with adjustment for age, parity, cervical cone biopsy, assisted reproduction and smoking. Associations between lifting and extremely (before 28 weeks), very (28-32 weeks) and moderately (33-37 weeks) preterm birth were analysed using Cox regression models. RESULTS: We found a dose-response relation between total daily burden lifted and preterm birth with an OR of 1.50 (95% CI 1.03 to 2.19) with loads over 1000 kg/day. No threshold value was found. The associations were strongest for extremely and very preterm birth with HRs (95% CIs) of 4.3 (1.4 to 13.8) and 1.7 (0.7 to 4.0), respectively. Lifting heavy loads (>20 kg) more than10 times/day was associated with preterm birth up to an OR of 2.03 (95% CI 1.14 to 3.62). CONCLUSION: In a society with social welfare and a highly regulated working environment, occupational lifting was associated with an increased risk of preterm birth.