A systematic review of musculoskeletal disorders among school teachers

Empirical research, case studies and literature reviews published in peer reviewed English journals were considered for inclusion, with letters to the Editor and conference proceedings excluded. Participants in the studies had to have been listed as school teachers. No restrictions were placed on age, gender, race or socioeconomic status. Only articles that documented the prevalence of MSD and its risk factors were considered. Articles not written in English were excluded from the literature review, as were studies which reported on university academic staff.

An extensive literature search was undertaken in MEDLINE and EMBASE databases during 2011. Further searches were performed in occupational health and safety databases such as CISILO database and MAK Collection for Occupational Health and Safety. Other relevant databases that were searched for publications included AMED, CINAHL, Scopus, ProQuest and PubMed. Following the initial database search, the reference lists of articles initially identified were then examined for additional publications. Keywords used for the search were; musculoskeletal disorders, musculoskeletal discomfort, back pain and teachers.

For all research articles identified during the search, the titles, keywords and abstracts, where available, were considered for possible relevance to this literature review. Full text copies were obtained for analysis and data extraction for all articles that met the inclusion criteria.

Following a thorough search of the databases, a total of 80 articles were located, albeit with a number of titles having been duplicated. The titles, keywords and abstracts (where available) were examined for relevance and assisted in the exclusion of duplicates. Following this process, a total of 40 potentially relevant papers were obtained. After further analysis of these articles, seven papers were excluded from the review as they did not measure the prevalence of MSD or demonstrate possible MSD risk factors among teachers. Articles that did not describe a research study or literature review were also excluded from the review. Following exclusions, a final group of 33 articles were considered suitable for the review.

The 33 studies located during this review had either measured the prevalence of MSD or reported on possible risk factors for MSD among teachers. All studies had been published in English. Figure 1 provides a flow chart of the literature search methodology.

International studies on MSD among school teachers have reported a high prevalence of MSD as indicated in Table 1. A number of articles reported a high prevalence of MSD, generally. A study of school teachers in Hong Kong, for example, found that 95.1% had experienced some form of pain in the previous month [14]. In a study carried out in Estonia which looked at physical activity, MSD and cardiovascular risk factors in male physical education teachers (PETs), 66.7% of teachers reported MSD in the previous 12 months, compared to 51.2% of PETs who reported MSD for the same period [16]. Furthermore, a study of Swedish music teachers found that 92% had experienced some form of pain in the previous 12 months [18], and a study of United States (US) music teachers found that 91% had experienced MSD [17]. In another Swedish study, 40% of school teachers and nursery school teachers were found to have reported MSD [13].

In more recent studies, MSD prevalence rates have been found to be 68% for music teachers in Perth, Australia [7], and 55% and 51.4% for school teachers in Brazil [3] and Turkey [15], respectively. Music teachers may be at an increased risk for MSD when compared with other school teachers. In comparison, PETs tended to have low risk of MSD, while preschool teachers have been reported to be at an increased risk of MSD [11]. As most of the studies reviewed had examined prevalence in selected musculoskeletal regions, these results will be examined separately.

Most studies have measured neck and shoulder pain separately as being 'neck pain' or 'shoulder pain,' although a few have combined them as 'neck and/or shoulder pain'. In a study of secondary school teachers in Hong Kong, the life-long prevalence of neck pain has been reported at 69.3%, within 12 month prevalence of 66.7%, and the prevalence after becoming a teacher being 59.7% [9]. Similar findings have been demonstrated in another Chinese study where secondary school teachers reported a life-long prevalence of neck pain as 68.2%, 64.4% for 12 months, and neck pain prevalence after becoming a teacher of 56.8% [6]. In a more recent Chinese study, school teachers reported a high neck pain prevalence rate of 68.9% for the previous month [14]. Parallels can be drawn to other studies where 59% of Swedish music teachers reported neck pain in the previous 12 months [19]. Furthermore, in a more recent study of Swedish music teachers, 47% reported having experienced neck pain in the previous 12 months [20]. Similar results have been found in another study of Swedish music teachers [18] where 44.4% experienced neck pain. In other studies, 42.5% of Turkish school teachers reported having experienced neck pain [15]. In comparison, PETs reported the lowest neck pain prevalence rate of all, being 9.3% [16].

The highest shoulder pain prevalence (73.4%) for the previous month has been reported by Chinese school teachers [14], while in Turkey, 28.7% of school teachers had experienced MSD symptoms in the shoulder area [15]. Furthermore, the prevalence of shoulder pain varied greatly between 28% and 55% in studies of Swedish music teachers carried out between 1988 and 2009 [16, 18‐20]. In Estonia, 7.8% of non-PETs and 18.6% of PETs reported pain on their shoulders [16]. In Japan, 25% to 35.4% of preschool teachers had experienced neck and/or shoulder pain in the previous month [21]. Comparable to these findings are the results of a US study in which 33% of preschool teachers reported neck and/or shoulder pain [11].

Several studies have investigated MSD in the upper extremities such as the elbows, wrist, arm or hands. Upper limb pain was reported by 72% of Japanese teachers of physically and intellectually disabled pupils [22], and by 23.7% of Brazilian school teachers [3]. In a Chinese study of secondary school teachers, 35.8% reported life-long upper limb pain whilst 33.3% had experienced upper limb pain in the previous 12 months and 31.8% had experienced upper limb pain since becoming a teacher [9]. Elbow pain has been reported as a symptom, mainly by music teachers. From the Swedish studies carried out among music teachers, the prevalence of elbow pain ranged between 11.1% and 22.2%. Pain in the hand region has also been the most prevalent symptom among Swedish music teachers, ranging from 13 - 22.2% of the teachers surveyed [18‐20]. Only 8% of school teachers in Turkey reported elbow pain [15], however, a total of 43.9% of primary and secondary school teachers in Hong Kong reported MSD in the arm during the previous month [14]. In contrast, 9.1% to 17.7% of Japanese preschool teachers reported having experienced arm pain, while 11% of US preschool teachers had experienced hand/wrist pain [11]. Wrist pain was a symptom reported by only 13% of the Turkish school teachers [15].

Many studies examined in the current review had measured back pain in different ways. Most reported back pain in general, while comparatively fewer studies reported low back and upper back pain separately. For example, 63% of Greece PETs [23] and 52.4% of teachers in a special school for the severely handicapped reported back pain [24]. Similar results were found in two studies conducted in Japan where 45.7% of teachers for physically and mentally handicapped children [25] and 76.7% of teachers for physically and intellectually disabled pupils [22] reported higher prevalence rates of back pain. The prevalence of back pain among preschool teachers also varied greatly. In two separate studies of Japanese preschool teachers, 17.7% [26] and 43.3% [5] reported back pain, while a higher prevalence of 61% has been reported among US preschool teachers [11].

In the Philippines and Brazil, 53.3% of secondary school teachers [8], and 41.1% of primary and secondary school teachers [3] have reported back pain, respectively. Parallels can be drawn to other studies where 40.4% of Malay teachers [1] and 40% of Chinese primary school teachers also reported back pain [27] in the 12 months prior to the study. In France, 34.8% of school teachers had experienced back pain in the previous six months [28]. Conversely, only 20.6% of Japanese preschool school teachers had experienced back pain [5].

Lower back pain appears to be more prevalent than upper back pain among teachers. Supporting this hypothesis is a Turkish study which found that 43.8% of school teachers reported low back pain, compared to 36.9% of whom reported upper back pain [15]. Similar results have been demonstrated in a Chinese study where 59.2% teachers reported low back pain compared to 52.5% who reported upper back pain [14]. Furthermore, a number of Swedish studies conducted among music teachers have found similar trends [18‐20]. It must be noted, however, that in Estonia, PETs reported a significantly lower prevalence of low back pain (4.7%), when compared to non-PETs (11.8%) [16].

A few studies have investigated MSD of the lower extremities such as hips, legs, knees, ankles and/or feet among teachers. MSD in the lower extremities have been reported by 41.1% and 33% of Brazilian school teachers [3] and US preschool teachers [11], respectively. In China, 54.6% of school teachers reported having experienced leg pain during physical activity in the previous month [14]. In a recent Turkish study, lower extremity pain had been experienced by 8.4% of teachers in the hip area, 32% in the knees and 21.8% in the ankles [15]. In another study, 12% of Swedish music teachers reported hip pain, 16% knee pain and 9% foot pain in the previous 12 months [19]. In Estonia, 3.9% of non-PETs reported hip pain in the previous 12 months, whilst 2.3% of PETs reported hip pain over the same time period. In comparison, in the same Estonian study, only 7.8% of non-PETs reported knee pain whilst 14% of PETs reported experiencing knee pain [16]. The prevalence of pain in the lower extremities of teachers seems to be relatively low when compared to the prevalence of pain in the upper extremities and the back.

Overall, this review suggests that while MSD is most likely an under researched topic among teachers, teaching itself represents a high risk occupation for MSD. The findings of this literature review have been drawn from 33 papers, each of which had measured different musculoskeletal regions using different methods. As most studies had used self-developed questionnaires [3, 7, 15, 21‐23, 26, 28], or the Standardized Nordic Questionnaire [1, 18, 27], it appears that these are commonly accepted methods for measuring the prevalence of MSD. Other methods used included pilot tested surveys and questionnaires such as the Northwick Neck Pain Questionnaire [6, 9], Health Questionnaires [25], Job Content questionnaires [5] and the Subjective Health Complaints Questionnaire [14]. While questionnaires are an inexpensive and convenient mode of data collection, they can introduce recall bias and make follow up difficult, especially when anonymous reporting is utilised. More accurate results might be obtained by physical examination and assessment, although these methods are expensive and time consuming, and therefore, ultimately uncommonly seen in the literature.

The response rate among most of the studies examined in this review was acceptable, although one investigation reported a response rate of only 3.5% [17]. For this study, the participants had been recruited during a conference using a poster placed near the main conference rooms. Some conference attendees might not have seen the poster while others might have been too busy with the conference proceedings to participate, consequently leading to the low response rate.

The most prevalent body regions on which teachers reported MSD have been the back [1, 3, 5, 8, 14‐16, 18‐20, 22‐28], neck [6, 9, 14, 15, 18‐20] and upper limbs [3, 9, 14, 15, 18‐20, 22]. It is important to note that while a number of studies have been carried out to specifically investigate back and neck pain, few studies have specifically looked at whole body MSD, and no studies have been carried out to specifically investigate lower extremity MSD. It is important, however, to note that the reported prevalence of back pain varied greatly across the literature, ranging from 4.7% to 76.7%.

Teachers of physically disabled pupils have reported the highest back pain prevalence [22] and this might be attributed to the lifting of the disabled pupils. On the other hand, PETs had reported the lowest back pain prevalence, and this may be because PETs are physically active and may also be involved in leisure-time physical activity [16]. However, the absence of personal training in order to maintain physical fitness among PETs could contribute to low back pain [23]. PETs have been reported to have a higher prevalence of knee disorders than non-PETs and were more likely to change work due to knee dysfunction [31].

MSD among teachers has been positively associated with female gender in a number of studies. It has been suggested that women might be more likely to report pain than men because women have lower physical strength, pressure from family and career prospects; or simply the fact that men and women have different traditions and thresholds for when and how they report pain [14]. While MSD has been positively associated with length of employment, research findings are somewhat inconsistent with some studies reporting longer length of employment as being positively associated with MSD, while others have reported that new teachers are more likely to report MSD. It has also been reported that the longer the exposure time to occupational risk factors, the higher the possibility of incurring job-related disorders [9]. This association can be interpreted as the effect of aging or a cumulative effect of workload on the musculoskeletal system of workers [21]. Where teachers with lesser teaching experience had reported MSD, it has been suggested that this may occur because new teachers might not be adapting well to the new working environment, and that physical and psychological stress might be affecting the wellbeing of their musculoskeletal conditions [9]. Further studies will be needed to investigate such a hypothesis.

The use of a 'head down' posture has been significantly associated with neck pain (OR: 2.17, 95% CI: 1.38-2.74) and this may impact on teachers who spend considerable time correcting students' work [9] and preparing for lessons. Neck pain among teachers has been positively correlated with computer processing posture [9]. It has been hypothesised that working with a 'poking chin' posture during computer processing might induce considerable load on the posterior, leading to increased loading on non-contractile structures and posterior cervical structures, thereby resulting in neck pain [9].

Psychosocial factors have been positively associated with MSD among school teachers, and the current review suggests that psychosocial factors such as high workload/demands, high perceived stress level, low social support, low job control, low job satisfaction and monotonous work are most likely associated with MSD among school teachers [1, 5, 6, 9, 21]. This may occur because teachers often work in stressful conditions with large classes, a lack of educational resources, and limited reward for their work [3].

A number of limitations were identified in this review. Recall bias and self-reporting can be considered as limitations for a number of studies, given that many used anonymous survey for data collection [3, 7‐9, 15, 19, 20, 25, 27, 28, 32, 33]. Cause and effect inferences cannot be ascertained, however, given that a number of studies used a cross-sectional study design [3, 7‐9, 19, 27]. Sample sizes and response rates were suboptimal in some studies [14, 17, 18]. Additionally, it must be noted that the review considered articles that were written in English only.