Associations between work-related factors and specific disorders at the elbow: a systematic literature review

Transcription

1 Rheumatology 2009;48: Advance Access publication 17 February 2009 doi: /rheumatology/kep013 Associations between work-related factors and specific disorders at the elbow: a systematic literature review Rogier M. van Rijn 1, Bionka M. A. Huisstede 1, Bart W. Koes 1 and Alex Burdorf 2 Objectives. To assess the exposure response relationships between work-related physical and psychosocial factors and lateral epicondylitis, medial epicondylitis, cubital tunnel syndrome and radial tunnel syndrome in occupational populations. Methods. A systematic review of the literature was conducted on the associations between type of work, physical load and psychosocial aspects at work and the occurrence of specific elbow disorders. Associations between work factors and these elbow disorders were expressed in quantitative measures: odds ratio (OR) or relative risk (RR).. Handling tools >1 kg (ORs of ), handling loads >20 kg at least 10 times/day (OR 2.6) and repetitive movements >2 h/day (ORs of ) were associated with lateral epicondylitis. Psychosocial factors associated with lateral epicondylitis were low job control (OR 2.2) and low social support (OR ). Handling loads >5 kg (2 times/min at minimum of 2 h/day), handling loads >20 kg at least 10 times/day, high hand grip forces for >1 h/day, repetitive movements for >2 h/day (ORs of ) and working with vibrating tools >2 h/day (OR 2.2) were associated with medial epicondylitis. The occurrence of cubital tunnel syndrome was associated with the factor holding a tool in position (OR 3.53). Handling loads >1 kg (OR 9.0; 95% CI 1.4, 56.9), static work of the hand during the majority of the cycle time (OR 5.9) and full extension (0 458) of the elbow (OR 4.9) were associated with radial tunnel syndrome. Conclusions. Several physical and psychosocial factors at work may result in an increased occurrence of specific disorders at the elbow. KEY WORDS: Musculoskeletal disorders, Lateral epicondylitis, Medial epicondylitis, Cubital tunnel syndrome, Radial tunnel syndrome, Review. Introduction Work-related upper extremity disorders are a common problem in working populations in western countries [1]. These complaints consist of a range of symptoms and disorders localized in the neck, shoulder, elbow and wrist/hand [1]. Recently, in the Netherlands consensus about the term complaints of the arm, neck and/or shoulder (CANS) was reached [2]. The CANS model distinguishes the following specific tendinopathies and neuropathies at the elbow: lateral epicondylitis, medial epicondylitis, cubital tunnel syndrome and radial tunnel syndrome [2]. Of these, epicondylitis (i.e. lateral epicondylitis and medial epicondylitis) is one of the most prevalent disorders, with an estimated prevalence of 5% in the general population, 8.9% among meat cutters and 14.5% among workers in the fish processing industry [3 6]. Silverstein et al. [7] reported a claim incidence rate for epicondylitis of 11.7/ full-time workers per year. Epicondylitis can be divided into lateral epicondylitis, known as tennis elbow, and medial epicondylitis, which is known as golfers elbow. Lateral epicondylitis and medial epicondylitis are the result of overuse of the extensor and flexor muscles, respectively, which lead to inflammation or irritation of the tendon insertion [8]. Certain workers are reported to be at increased risk for these disorders. The prevalence of lateral epicondylitis and medial epicondylitis in workers whose job required repetitive work varied from 1.3 to 12.2% and from 0.2 to 3.8%, respectively [6, 9 14]. Shiri et al. [6] have concluded that occupational physical factors such as repetitive movements of hands or wrists, handling loads heavier than 5 kg, activities demanding high hand grip forces and the use of vibrating tools were risk factors for lateral epicondylitis and medial epicondylitis. Cubital tunnel syndrome is the second most common nerve entrapment in the upper limb and is caused by pressure on or stretch of the nervus ulnaris near the elbow at the cubital tunnel [15, 16]. Mondelli et al. [17] reported an incidence of 24.7/ person-year in a general population. The prevalence of cubital tunnel syndrome reported in the literature varied from 2.8% among workers whose occupations required repetitive work to 6.8% in floor cleaners [15, 18]. Also, employees working with flexed elbows and direct pressure on the ulnar nerve are at risk for the development of cubital tunnel syndrome [16]. Less often seen is radial tunnel syndrome. There are different hypotheses about the cause of radial tunnel syndrome [19, 20]. Some attribute radial tunnel syndrome to compression of the radial nerve in the radial tunnel of the upper arm [21, 22]. Others suggested that radial tunnel syndrome is caused by a lesion in the supinator muscle or in the septum between the extensor muscles of the forearm [23]. Little information is available about occurrence of radial tunnel syndrome in working populations. Various psychosocial work factors have been reported to influence symptoms of elbow, wrist and hand, but information on their associations with the four specific tendino- and neuropathies of the elbow and psychosocial factors is scarce. Until now, available reviews have only presented overviews of occupations at risk and occupational risk factors for epicondylitis. However, little information is given with regard to the duration and magnitude of exposure to risk factors that are associated with the occurrence of lateral epicondylitis and medial epicondylitis and cubital tunnel syndrome or radial tunnel syndrome. Therefore, a systematic review of the available evidence in the scientific literature was conducted with the aim to provide a quantitative assessment of the exposure response associations between work-related physical and psychosocial exposures and the occurrence of lateral epicondylitis, medial epicondylitis, cubital tunnel syndrome and radial tunnel syndrome. 1 Department of General Practice and 2 Department of Public Health, Erasmus MC, Rotterdam, The Netherlands. Submitted 7 October 2008; revised version accepted 13 January Correspondence to: Rogier M. van Rijn, Department of General Practice, Erasmus MC, Room wk-109, PO Box 2040, 3000 CA Rotterdam, The Netherlands. r.vanrijn@erasmusmc.nl Methods Literature search Comprehensive literature searches were conducted by the first author (R.M.vR.) using DLINE (from 1966 to September 2007), Embase (from 1984 to September 2007) and the Cochrane Central Register of Controlled Trials. The keywords used 528 ß The Author Published by Oxford University Press on behalf of the British Society for Rheumatology. All rights reserved. For Permissions, please journals.permissions@oxfordjournals.org

2 Work and elbow disorders 529 are: for lateral epicondylitis: tennis elbow OR lateral epicondylitis; for medial epicondylitis: medial epicondylitis OR epicondylitis; for cubital tunnel syndrome: cubital tunnel syndrome OR ulnar nerve compression syndrome; for radial tunnel syndrome: radial neuropathy OR radial tunnel syndrome; for exposure: work related OR physical load OR psychosocial load OR exposure; and for association: association OR risk factors OR odds ratio OR relative risk. The complete search strategy is available at request. Two reviewers (R.M.vR. and B.M.A.H.) independently selected the articles initially based on title and abstract. For final inclusion articles had to fulfil all of the following criteria: (i) the occurrence of lateral epicondylitis, medial epicondylitis, cubital tunnel syndrome or radial tunnel syndrome was reported on occupational populations; (ii) a quantitative description of the measures of exposure was presented; (iii) the association between work-related risk factors and one of the disorders at the elbow was expressed in a quantitative measure, such as odds ratio (OR) or relative risk (RR); and (iv) the article was published in peer-reviewed scientific journals written in English, German, French or Dutch. A consensus method was used to resolve disagreements. Assessment of methodological quality A quality assessment list was constructed using criteria from Huisstede et al. [20], Lievense et al. [24], Van Tulder et al. [25] and the Dutch Cochrane Centre, which were adapted to the specific aim of this review (see supplementary data appendix II, available at Rheumatology Online). The list covers five topics, with 16 items in total, namely: study population, assessment of exposure, assessment of outcome, study design and analysis and data presentation (Table 1). Two reviewers (A.B. and B.W.K.) independently assessed the quality of each study by scoring each criterion as positive, negative or unclear. Disagreements were resolved by consensus. The quality score for every study was calculated by summing the number of positive criteria. Data extraction Relevant data from the articles were extracted by the first author (R.M.vR.). Information was collected on the study population, study design, outcome ascertainment, exposure characteristics, measure of association and confounding factors using a standardized form. The core findings in each article were expressed by measures of association (ORs or RRs) with corresponding 95% CIs. Where possible these associations were directly extracted from the original article. In articles where this information was not presented, associations were calculated if sufficiently raw data were provided. Data analysis In this review three types of statistical associations were distinguished. The association was described as positive when the occurrence of one of the four disorders at the elbow was statistically associated with higher values of the risk factor. In a negative association, a higher value of the risk factor was statistically associated with a lower occurrence of one of the four disorders at the elbow. In null associations, the risk estimate was not statistically different from unity. The null associations were further evaluated as to whether the results actually suggest the absence of an effect or whether the studies were inconclusive due to lack of information. Pooling of the results of individual studies was considered only when health outcomes were clinically homogeneous and the measures of exposure were sufficiently similar according to the reviewers. The outcome of the quality assessment was used in a sensitivity analysis to evaluate whether design characteristics and methodological quality of studies have an impact on the reported associations between work-related risk factors and one of the four disorders at the elbow. First, we will focus on the association between type of work (based on, for example, job title) and the occurrence of one of the four disorders at the elbow. Secondly, we will focus in more detail on the association of four types of exposure and a mixture of these exposures to physical load and the occurrence of one of the four disorders at the elbow. The four types of exposure were: (i) force, (ii) repetitiveness, (iii) hand arm vibration and (iv) posture. Finally, we focused on the association of psychosocial risk factors and the occurrence of the four disorders at the elbow. Characteristics of the included articles Our search resulted in 633 potentially relevant articles (Fig. 1). Of these, 13 publications met our inclusion criteria: 9 crosssectional studies, 2 case control studies and 2 cohort studies SEARCH TAB 1. Methodological quality assessment Medline EMbase CCRCT Criteria Score Study population 1 Study groups are (exposed and unexposed) clearly defined þ/ /? 2 Participation 570% þ/ /? 3 Cases 550 þ/ /? Assessment of exposure Adequate description of the exposure 4 Exposure definition þ/ /? 5 Assessment of exposure þ/ /? 6 Blind for outcome status þ/ /? Assessment of outcome (specific disorder) Adequate description of the outcome 7 Outcome definition þ/ /? 8 Assessment method þ/ /? 9 Blind for exposure status þ/ /? Study design 10 Prospective design þ/ /? 11 Inclusion and exclusion criteria þ/ /? 12 Follow-up period 51 year þ/ /? 13 Information between completers vs withdrawals þ/ /? Analysis and data presentation 14 Data presentation þ/ /? Identifying confounders 15 Consideration of confounders þ/ /? 16 Control for confounding þ/ /? Potentially relevant articles identified and screened for retrieval (n = 633) Articles retrieved for more detailed evaluation (n =188) Potentially relevant articles identified and screened for retrieval (n = 54) Articles included in the systematic review (n = 13) FIG. 1. Flow chart of the selected articles. Articles excluded based on title (n = 445) Articles excluded based on abstract (n =134) Studies excluded: Do not meet inclusion criteria (n = 42) Studies retrieved by other sources: Screening of references (n = 1)

3 530 Rogier M. van Rijn et al. TAB 2. Studies that report the risk of musculoskeletal disorders in the elbow region by job title Study population Reference Study design Exposed Reference Outcome OR 95% CI Luopajarvi et al. [11] CS Female asssembly line workers in a food production factory (152) Female shop assistants (133) , 5.33 Roto and Kivi [5] CS meat cutters (90) Foremen construction industry (72) , 56.7 Wang et al. [26] CS Female betel pepper leaf cullers (20) Female non-cullers (47) , 6.90 CS, cross-sectional;, lateral epicondylitis. (see supplementary data appendix I, available at Rheumatology Online). Three articles compared the occurrence of lateral epicondylitis across occupations (Table 2) [5, 11, 26]. Seven articles reported on associations of physical risk factors and lateral epicondylitis [4, 6, 10, 12, 13, 27, 28]. Of these, three articles also reported on the association of physical risk factors and medial epicondylitis [6, 12, 13]. Three articles reported, separately, on associations of physical risk factors and medial epicondylitis, cubital tunnel syndrome and radial tunnel syndrome alone (Table 3) [9, 15, 29]. The associations between psychosocial factors and the occurrence of lateral epicondylitis and cubital tunnel syndrome were presented in two and one article respectively (Table 4) [10, 15, 28]. Methodological quality The methodological quality assessment of the included articles is presented in Table 5 and the quality score ranged from 3 to 15. The initial agreement of the two reviewers was 77% (160 of 208 items). Initial disagreements were all solved in a consensus meeting. A higher quality score was associated with the likelihood of reporting a significant association (Fig. 2). Figure 3 shows that 46% of the articles (n ¼ 6) with a high quality score (511) were published in the last 8 years. Job title and occurrence of lateral epicondylitis Only three articles reported on the association between job titles and the occurrence of lateral epicondylitis [5, 11, 26]. In these articles no significant associations were found. In male meat cutters an OR of 6.93 (95% CI of 0.85, 56.7) was found. The prevalence of lateral epicondylitis in this occupation was 1% [5]. Exposure and occurrence of lateral epicondylitis Force. A case control study showed a significant association between handling loads >20 kg at least 10 times/day for >20 years and lateral epicondylitis (OR 2.6), but no significant effects of handling loads >5 kg at least 2 times/min for 2 h/day and high hand grip forces for at least >1 h/day (OR ) [6]. Further, a cross-sectional study reported significant associations between handling tools 51 kg and lateral epicondylitis (OR ) [10]. Repetitiveness. Four articles reported on the association between repetitiveness and the occurrence of lateral epicondylitis. Highly repetitive hand arm movements were a risk factor for lateral epicondylitis (OR 4.7) [12]. In a cross-sectional study, repetitive movements >2 h/day for 9 19 years and 520 years were statistically associated with the occurrence of lateral epicondylitis, with ORs of 2.4 and 2.8, respectively [6, 12]. Besides, a significant association was found in female workers between movements of the arm for 75 to almost 100% of the time and lateral epicondylitis, with an OR of 3.7 [10]. Hand arm vibration. Using a hand-held vibrating tool for 25 50% of the time was associated with lateral epicondylitis in male workers, but not in female workers, with an OR of 2.9 [10]. However, no associations were found in using a hand-held vibrating tool for 75 to almost 100% of the time and lateral epicondylitis [10]. Besides, working with vibrating tools >2 h/day was not associated with the occurrence of lateral epicondylitis, with an OR of 0.7 [6]. Posture. In a cohort study among employees working in different branches of industry, the exposure turn and screw was associated with the development of lateral epicondylitis (OR 2.07) [28]. In a case control study it was reported that arms lifted in front of the body, hands bent or twist, and precision movements during a part of the working day were risk factors for lateral epicondylitis in female as well as male workers (ORs of ) [10]. Combined exposure measure. One article found statistically significant associations between combinations of exposures (force, repetitiveness and posture) and the occurrence of lateral epicondylitis [10]. In female workers three combinations of exposure (low repetition extreme posture, high repetition extreme posture and high force extreme posture) showed an association with the occurrence of lateral epicondylitis, with ORs of In these combinations extreme posture was always a part of the exposure. In male workers, a combination of high repetition high force and high force neutral posture was associated with lateral epicondylitis, with ORs 3.5 and 3.3, respectively. Here, high force was always a part of the exposure. In workers in the fish processing industry associations, although not significant, were found between high repetition or high force and high repetition and high force, with ORs of 1.65 and 2.50, respectively [4]. Psychosocial risk factors. Low job control and low social support at work were positively associated with the occurrence of lateral epicondylitis in the general workforce with ORs of 2.2 and, respectively [10]. Depressive symptoms and high job demands were not clearly related with an increased risk to develop lateral epicondylitis [10, 28]. Exposure and occurrence of medial epicondylitis Force. Handling loads >5 kg for 2 times/min at a minimum of 2 h/day (1 8 years), handling loads >20 kg for 10 times/day (1 8 and 520 years) and working with high hand grip forces >1 h/day (1 8 and 520 years) were positively associated with the presence of medial epicondylitis, with ORs varying between 2.2 and 2.5 [6]. Repetitiveness. The exposure to repetitive movements >2 h/day was positively associated with the occurrence of medial epicondylitis and increased with longer exposure duration, with ORs of 2.2 (9 19 years) and 3.6 (520 years) [6]. An association, although not significant, was found in female cooks and nurses who were exposed to highly repetitive hand arm movements with an OR of 12.4 (95% CI 0.6, 242). The prevalence of medial epicondylitis in this population was 1.4%. Hand arm vibration. Working with vibrating tools >2 h/day was associated with the occurrence of medial epicondylitis, OR of 2.2. The examined working population was selected at random from a National Population Register [6].

4 Work and elbow disorders 531 TAB 3. Studies that report the risk of musculoskeletal disorders in the elbow region by physical risk factors in the occupation Author (year) Study design Study population Outcome Physical risk factor OR 95% CI Force Haahr and Andersen [10] CC General population who were Handling tools of 51 kg (yes vs no) , , 3.8 Descatha et al. [9] CS Workers whose jobs involved repetitive work (assembly line, clothing and shoe industry, food industry, packaging and cashiers) (1757) Descatha et al. [15] Cohort Workers whose jobs involved repetitive work (assembly line, clothing and shoe industry, food industry, packaging and cashiers) with 3-year follow-up (598) Roquelaure et al. [29] CC Workers with RTS (21 cases) and workers without RTS (21 referents) in three plants were TV sets, shoes and automobile breaks were manufactured Ono et al. [12] CS Female cooks in nursery schools (209) and female nursing assistants, nurses for the aged and handicapped, home care service workers, handywomen (366) Hansson et al. [27] CS Female workers in a laminate industry and performing repetitive work (95) vs female workers in same company with mobile and varied works tasks and office workers (74) Haahr and Andersen [10] CC General population who were Shiri et al. [26] CS Working population selected Handling of loads >5 kg (year) Handling of loads >20 kg (year) High hand grip forces (year) 9 19 vs vs 1 8 Forceful work (yes/no) Pressing with the hand (yes/no) Handling of loads >5 kg (year) Handling of loads >20 kg (year) High hand grip forces (year) , , , , , , , , , , , , , , , , , , , 4.5 Cubital Working with force (yes/no) , 3.22 RTS High force , 56.9 Repetitiveness Highly repetitive hand arm movements vs no highly repetitive hand arm movements Repetitive work vs no repetitive work Movements of fingers or hands three-quarters to almost all the time vs never Movements of arm Repetitive movements (year) , , , , , , , , , , , , , 5.8 (continued)

5 532 Rogier M. van Rijn et al. TAB 3. Continued Author (year) Study design Study population Outcome Physical risk factor OR 95% CI Ono et al. [12] CS Female cooks in nursery schools (209) and female nursing assistants, nurses for the aged and handicapped, home care service workers, handywomen (366) Shiri et al. [26] CS Working population selected Haahr and Andersen [10] CC General population who were Descatha et al. [15] Cohort Workers whose jobs involved repetitive work (assembly line, clothing and shoe industry, food industry, packaging and cashiers) with 3-year follow-up (598) Ritz [13] CS Male workers of gas and waterworks (290) Leclerc et al. [28] Cohort Employees in different branches of activity at national level (assembly line, clothing and shoe industry, food industry, packaging and supermarket cashiers) with 3-year follow-up (525) Haahr and Andersen [10] CC General population who were Ritz [13] CS Male workers of gas and waterworks (290) Descatha et al. [15] Cohort Workers whose jobs involved repetitive work (assembly line, clothing and shoe industry, food industry, packaging and cashiers) with 3-year follow-up (598) Highly repetitive hand arm movements vs no highly repetitive hand arm movements Repetitive movements (year) Hand arm vibration Using hand-held vibrating tools , , , , , , , , 5.3 Work with vibrating tools , 2.1 Work with vibrating tools Yes vs no , 4.4 Cubital Using a vibrating tool (yes/no) , 5.46 Posture High elbow strain vs no elbow strain , 3.99 Moderate elbow strain vs no elbow , 2.41 strain Turn and screw , 3.70 Arms lifted in front of body Hands bent or twist Precision movements , , , , , , , , , , , , 17.9 Keying , 1.1 Cubital High elbow strain vs no elbow strain Moderate elbow strain vs no elbow strain , , 3.42 Keying Yes vs no , 0.9 Holding in position (yes/no) Turning and screwing (yes/no) Using of elbow support (yes/no) Holding a tool in position (yes/no) , , , , (continued)

6 Work and elbow disorders 533 TAB 3. Continued Author (year) Study design Study population Outcome Physical risk factor OR 95% CI Roquelaure et al. [29] CC Workers with RTS (21 cases) and workers without RTS (21 referents) in three plants where TV sets, shoes and automobile breaks were manufactured Chiang et al. [4] CS Workers in the fish processing industry (207) Haahr and Andersen [10] CC General population who were RTS Static work Full extension of the elbow Combined exposure measure High repetitive or high force vs low repetitive and low force High repetitive and high force vs low repetitive and low force Repetition (R) and force (F) Low R, high F vs Low R, F High R, low F vs Low R, F High R, F vs Low R, F Repetition (R) and posture (P) Low R, extreme P vs Low R, neutral P High R, neutral P vs Low R, neutral P High R, extreme P vs Low R, neutral P Force (F) and posture (P): Low F, extreme P vs Low F, neutral P High F, neutral P vs Low F, neutral P High F, extreme P vs Low F, neutral P CC, case control; CS, cross-sectional;, lateral epicondylitis;, medial epicondylitis; Cubital, cubital tunnel syndrome; RTS, radial tunnel syndrome , , , , , , , , , , , , , , , , , , , , , , 4.5 Posture. Two articles described the association between postural load and medial epicondylitis. A negative association (OR 0.5) was found in employees exposed to keying in relation to medial epicondylitis [6]. No association was found between high and moderate elbow strain and medial epicondylitis [13]. Exposure and occurrence of cubital tunnel syndrome Only one cohort study described the association between physical load factors and psychosocial aspects at work and the development of cubital tunnel syndrome in workers whose jobs involved repetitive work [15]. This study showed a significant association between holding a tool in position and cubital tunnel syndrome (OR 3.53). Null associations were reported between working with force, and using a vibrating tool and the development of cubital tunnel syndrome, with ORs of 1.13 (95% CI 0.40, 3.22) and 1.70 (95% CI 0.53, 5.46), respectively. Besides, exposure to turning and screwing and low job control were not associated with the development of cubital tunnel syndrome. Exposure and occurrence of radial tunnel syndrome The case control study of Roquelaure et al. [29] reported significant associations between exposure to force, and postural load and the occurrence of radial tunnel syndrome, with ORs ranging from 4.9 to 9.0. Working with a load >1 kg with a frequency of exertion of 10 times/h, static work of the hand during the majority of the cycle time and full extension (0 458) of the elbow were risk factors for RTS. Discussion This review evaluated the association between occupations, physical and psychosocial risk factors and the occurrence of lateral epicondylitis, medial epicondylitis, cubital tunnel syndrome and radial tunnel syndrome. Frequent handling of loads, highly repetitive movements and forceful work were associated with the occurrence of lateral epicondylitis and medial epicondylitis. Postural load, low job control and low social support were associated with lateral epicondylitis alone. Hand arm vibration was only associated with the occurrence of medial epicondylitis. Furthermore, postural load was associated with the occurrence of cubital tunnel syndrome as well as radial tunnel syndrome. Besides, frequent handling of loads was associated with radial tunnel syndrome alone. The evidence for the above mentioned associations is primarily based on results presented in crosssectional studies, therefore the causality of the reported associations between exposure and the occurrence of one of the specific disorders at the elbow is debatable. The two cohort studies included evaluated the relation of psychosocial and physical factors with, respectively, lateral epicondylitis and cubital tunnel syndrome. The two cohort studies were initially the same longitudinal studies, but the authors used a different health outcome. Descatha and colleagues [15] found 15 incident cases

7 534 Rogier M. van Rijn et al. TAB 4. Psychosocial risk factors and work-related musculoskeletal disorders in the elbow region References Study design Study population (n) Outcome Psychosocial risk factor OR 95% CI Leclerc et al. [28] Cohort Employees in different branches of activity at Depressive symptoms , 2.90 national level (assembly line, clothing and shoe industry, food industry, packaging and supermarket cashiers) with 3 year follow-up (525) Haahr and Anderson [10] CC General population who were enrolled in the practices of the High job demands Low job control Low social support at work , , , 2.7 Descatha et al. [15] Cohort Workers whose jobs involved repetitive work (assembly line, clothing and shoe industry, food industry, packaging and cashiers) with 3-year follow-up (598) CC, case-control;, lateral epicondylitis; Cubital, cubital tunnel syndrome. Cubital Low job control, defined as a score of 55 (sum of 8 yes/no items) , 3.37 TAB 5. Methodological quality scores of the included articles Reference Score Leclerc et al. [28] þ þ þ þ þ þ þ þ þ þ þ þ þ þ þ 15 Shiri et al. [6], þ þ þ þ þ þ þ þ? þ þ þ þ þ 13 Descatha et al. [9] þ þ þ þ þ þ þ þ þ þ þ þ 12 Descatha et al. [15] CUTS þ þ þ þ þ þ þ þ þ þ þ þ 12 Roquelaure et al. [29] RTS þ? þ þ þ þ þ þ þ þ þ þ 11 Haahr and Anderson [10] þ þ þ þ þ þ þ þ þ þ þ 11 Ono et al. [12], þ þ þ þ þ þ þ þ þ þ 10 Roto and Kivi [5] þ? þ þ þ þ þ þ þ þ þ 10 Chiang et al. [4]? þ þ þ þ þ þ þ þ þ 9 Ritz et al. [13], þ þ þ þ þ þ þ þ þ 9 Hansson et al. [27] þ þ þ þ? þ þ þ þ 8 Luopajärvi et al. [11] þ þ þ þ þ þ 6 Wang et al. [26] þ þ þ þ þ þ 6, lateral epicondylitis;, medial epicondylitis; Cubital, cubital tunnel syndrome; RTS, radial tunnel syndrome. Methodological quality score NS Level of significance FIG. 2. Association between methodological quality and level of significance of all included articles that evaluated the association between job title/risk factors and the development of lateral epicondylitis, medial epicondylitis, cubital tunnel syndrome and radial tunnel syndrome. of cubital tunnel syndrome among 598 industrial workers during a 3-year follow-up, resulting in an estimated incidence of 8.4/1000 person-years. A large heterogeneity was observed in the assessment of exposure to physical risk factors. None of the included articles used the same definition to determine exposure to force, repetitiveness, hand arm vibration or awkward posture. Besides, six studies (46%) used questionnaires or interviews only to determine magnitude, frequency or duration of exposure. S 6 Methodological quality score Year of publication FIG. 3. Association between methodological quality and year of publication of all articles that evaluated the association between job title/risk factors and the development-specific disorders at the elbow. The diagnosis of lateral epicondylitis, medial epicondylitis, cubital tunnel syndrome or radial tunnel syndrome was made using different diagnostic tools, namely: questionnaires, physical examination and electrophysiological examination. In 62% (n ¼ 8) of the studies, a combination of physical examination and selfreported complaints was used. In none of the studies the diagnosis was based on self-reported complaints only. The scores on the methodological quality assessment ranged from 4 to 15 (on a scale from 0 to 16). The items study design was prospective or a retrospective cohort and follow-up period

8 Work and elbow disorders 535 was 51 year were scored positive in only 23% of the articles (n ¼ 3), due to a lack of cohort studies. Other critical items were total number of cases was 550 (n ¼ 3), participation of the exposed group and unexposed group was 570% (n ¼ 5) and demographic information between completers vs withdrawals (n ¼ 5). The methodological quality score of a study was associated with the presence of a significant association between workrelated factors and specific disorders at the elbow. It is promising to notice that the methodological quality score of the included articles seemed to have improved over time, since the studies with highest quality were predominantly published in the past years. In a recent review by Palmer et al. [30], risk of epicondylitis was described by job title. However, in the current study, epicondylitis was subdivided in lateral and medial epicondylitis. Articles that only reported results concerning epicondylitis were excluded. Palmer and colleagues found an increased risk for epicondylitis in vibration exposed workers, foresters, pipe fitter and water/gas suppliers, meat cutters, packers and Japanese nursery school cooks. In line with these findings are the results of the present study in which we found an increased risk for lateral epicondylitis in men meat cutters. The current review extends the existing knowledge with quantitative information of exposure response relationships between work-related factors and the occurrence of four specific disorders at the elbow. Unfortunately, pooling of study results was not possible for exposure to all of the risk factors because of the large heterogeneity in exposure assessment and the ascertainment of the diagnosis of the specific disorders at the elbow. A comparison of the results found across studies on lateral epicondylitis and medial epicondylitis showed us that there are some differences between exposures and the occurrence. It seems that there is more evidence for the relationship between forceful work and exposure to hand arm vibration and medial epicondylitis compared with the association between these physical risk factors and lateral epicondylitis. The results for the association between repetitiveness and lateral epicondylitis or medial epicondylitis show no differences between both disorders. Thus, in future research, it will be worth making a distinction between lateral epicondylitis and medial epicondylitis in order to investigate disorder-specific physical and psychosocial risk factors. Cubital tunnel syndrome is the second most common nerve entrapment at the upper limb after carpal tunnel syndrome, but the literature about this complaint in a working population is scarce. In a review by Piligian et al. [31], some work-related risk factors were mentioned and appeared to be common to cubital tunnel syndrome: repetitive and sudden elbow flexion, and repeated trauma or pressure to the elbow at the ulnar groove. However, no quantitative information from this review is available. The findings in this systematic review cannot confirm these associations. Just as for cubital tunnel syndrome, relevant literature about radial tunnel syndrome in an occupational setting is mostly lacking. However, the study of Roquelaure et al. [29] demonstrated that forceful work, hand arm vibration and postural load are associated with the development of radial tunnel syndrome. However, these findings need to be corroborated in longitudinal studies. In summary, with this overview some quantitative information is available on duration and magnitude of exposure to physical risk factors. This systematic review provides indications that the occurrence of lateral epicondylitis is associated with the following physical risk factors: handling loads >20 kg (at least 10 times/day), handling tools >1 kg, repetitive hand/arm movements >2 h/day, arms lifted in front of the body, hands bent or twist and precision movements during a part of the working day. Psychosocial risk factors that are associated with the occurrence of lateral epicondylitis are: low job control and low social support. Risk factors associated with the occurrence of medial epicondylitis were: handling loads >5 kg (2 times/min at a minimum of 2 h/day), handling loads >20 kg (at least 10 times/day), high hand grip forces >1 h/day, repetitive movements >2 h/day and using vibrating tools >2 h/day. Furthermore, the current study provides information that the occurrence of cubital tunnel syndrome is associated with the risk factor holding a tool in position. 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