Introduction
Musculoskeletal disorders are among the most common and costly occupational injuries in developed and developing countries, especially prevalent among teachers [1]. National Occupational Research Agenda (NORA) programs in the United States indicate that work-related musculoskeletal injuries are a major component of healthcare costs in the United States, estimated at around 59-13 billion dollars annually [2]. Musculoskeletal disorders affect up to 95% of teachers in various body regions and are considered a primary occupational health hazard, leading to absenteeism, early retirement, decreased quality of life, and teaching quality [2]. Risk factors for these disorders include age, body mass index (BMI), work history, and number of working hours, especially sitting and standing hours during the day. Aging and increased BMI lead to gradual muscle mass reduction, decreased connective tissue flexibility, increased pressure, joint cartilage degeneration, and decreased tissue quality. Additionally, maintaining a prolonged body position such as standing or sitting, repetitive movements, poor posture (like neck and back bending) for extended periods, long working hours over time, and years of experience contribute to inappropriate musculoskeletal conditions in teachers [2-8].
Furthermore, research indicates a relationship between gender and musculoskeletal disorders, with a higher prevalence of these disorders reported in women compared to men [5]. Factors such as low pain threshold, female body anatomy, daily household chores, lower wages, higher responsibility, and higher work demands compared to men have led to differences in the prevalence of musculoskeletal disorders between genders [6]. Therefore, given the high prevalence of musculoskeletal disorders and the complex nature of associated risk factors, intervention strategies may be challenging and complex in reducing and treating musculoskeletal disorders in female teachers. Conducting studies in various communities, including Damascus, to examine the prevalence of musculoskeletal disorders in different body regions and investigate risk factors in this area can significantly aid in preventing and treating teachers, especially women at higher risk. Thus, the present study aims to investigate the prevalence and identify risk factors for musculoskeletal disorders in female teachers of middle and high schools in Damascus, which has not been done before. 

Materials and Methods 
This study is a descriptive cross-sectional epidemiological study. The study population included female teachers working in middle and high schools in Damascus in the spring and summer of 1402. According to a study by Althomali et al. conducted in Saudi Arabia, the prevalence of wrist pain was estimated at 40% (P=0.4), considering a 95% confidence level (z=1.96) and a 5% error rate (d=0.05) and using the sample size formula (Equation 1), a sample size of 368 individuals was determined [2].


The samples were selected in a two-stage cluster sampling based on the inclusion and exclusion criteria. According to information from schools in Damascus City, there are 305 private schools (middle and high schools) and 571 public schools (middle and high schools). Schools are located in 15 regions. One private school (15 classes) and two public schools (30 classes) from each region, totaling 45 schools, were randomly selected in this design. Eight or nine teachers from the selected schools were chosen and invited to participate in the study. 

The inclusion and exclusion criteria
The inclusion criteria were female teachers working in middle and high schools in Damascus who were willing to participate in the study, had at least 1 year of work experience, were between 20 and 50, and had no specific medical treatment [5]. 
The exclusion criteria were unwillingness to continue cooperation, incomplete questionnaire completion, pregnancy, and musculoskeletal system injuries resulting from accidents, trauma, or surgery [5]. 
Initially, ethical approval for the research (IR.USWR.REC.1402.109) was obtained from the Ethics Committee of the University of Social Welfare and Rehabilitation Sciences, Iran, Tehran, and necessary approvals were obtained from the Ministry of Education in Syria, Damascus City. The researcher then visited the research units, explained the research objectives, informed individuals about the confidentiality of their information, and obtained written consent from them to participate in the study. In this study, demographic and Nordic questionnaires were used to collect data. 
The demographic questionnaire contained personal information such as name, work experience, teaching level, age, weight, height, working hours, work history, and number of hours standing and sitting per day. The Nordic questionnaire was designed by Kuorinka et al. [9]. This questionnaire consists of 27 sections recording symptoms of musculoskeletal disorders throughout the body. This questionnaire can be used to assess the results of epidemiological studies on musculoskeletal disorders. It is one of the most widely used questionnaires for investigating musculoskeletal disorders [10], and Amer et al. confirmed its Arabic version’s validity and reliability [11]. 
Data analysis was performed using SPSS version 27 software. A significance level of 0.05 was considered for the study. The prevalence of various types of pain in each body part was reported in 3 time points with the number and percentage. An independent t test (for quantitative variables) was used to determine background factors associated with each type of disorder in teachers at 3 time points. Then, each variable was defined as a single-variable regression model. Any variable with a probability value above 0.2 was entered into a multivariable logistic regression model. The odds ratios of these models are presented as the outcome of the findings.

Results 
This study showed that over the past 12 months, the prevalence of musculoskeletal disorders in different body regions varied among participants. The distribution of musculoskeletal disorders in different body regions among participants at 3 different time points is shown in Table 1. 


In the surveys conducted, the prevalence of musculoskeletal disorders resulting from work in the past 12 months in teachers was experienced primarily in the lower back (85.7%), followed by the neck (70%), shoulder (62.4%), wrist (60.2%), knee (59%), ankle (36%), thigh (35%), back (35.1%), and elbow (30.5%). 
In disorders that led to disability and hindrance in performing tasks in the past 12 months, teachers experienced the most pain in the lower back (70.3%), followed by the neck (66.6%), shoulder (50.6%), and wrist (50.4%). Almost half of the participants (49.4%) had knee pain. 
In disorders resulting from work in the past week, teachers experienced the most pain in the lower back (41.6%), followed by the neck (41%), shoulder (41%), and wrist (41.8%). Also, 41.3% had knee pain. 
Demographic variables “quantitatively” compared among teacher participants based on musculoskeletal disorders in different body regions in three different time intervals are presented in Table 2. 




Based on Table 2 and considering the time points of musculoskeletal disorders resulting from work in the past 12 months, the following information was obtained regarding relevant factors: 
average age, work experience, working hours, and standing hours per day among teachers with neck pain and those without significant differences (P>0.05). 
Similarly, the average age, work experience, and number of standing and sitting hours during the day among teachers who had back pain and those who did not show a significant difference (P>0.05). 
The findings indicated that among demographic variables, BMI and the average number of standing and sitting hours during the day among teachers who had lower back pain and those who did not show a significant difference (P>0.05). 
The average age and BMI among teachers who had thigh pain and those who did not showed a significant difference, too (P>0.05). 
Additionally, the average age, BMI, work experience, number of working hours per day, and number of standing hours during the day among teachers who had knee pain and those who did not show a significant difference (P>0.05). 
Furthermore, the results showed a significant difference in the average BMI, number of working hours, and standing duration among teachers with ankle pain and those without (P>0.05). 
Table 3 presents the results of the multivariable logistic regression model for examining factors associated with pain in each region and time interval.


The numbers inside the Table represent the odds ratio. If a variable was not significant, it is indicated in the Table with a dashed line, and the results are summarized as follows in different regions: 
Regarding the neck, two variables, “work experience” and “sitting hours,” are predictive variables for neck disorders in the past 12 months. Based on this, the chance of having a neck disorder for teachers with more than 20 years of work experience is 3.65 times higher than for teachers with less than 20 years of experience. The chance of a neck disorder increases by 1.76 times for teachers with each additional sitting hour. 
The predictive variables for disability in the past 12 months due to neck pain are BMI and sitting hours. The chance of disability due to neck pain for teachers with a BMI over 25 kg/m2 (overweight and obese) is approximately 1.77 times higher than for other teachers. The chance of disability due to neck pain increases by 2.03 times for teachers with each additional sitting hour. 
Additionally, the predictive variable for developing a neck disorder in the past 7 days is work experience. The chance of developing a neck disorder in teachers with more than 20 years of work experience is 2.04 times higher than in teachers with less experience. 
Regarding the shoulder, work experience of over 20 years in all three intervals (1, 2, and 3) leads to a 2.28, 2.54, and 2.49 times higher likelihood of disorder or disability than teachers with less experience. 
Considering the elbow, in the elbow region, a BMI over 25 kg/m2 leads to a 1.77, 2.06, and 1.83 times higher likelihood of disorder or disability compared to a lower BMI in all three intervals, respectively. Additionally, work experience of over 20 years leads to a 2.15 times higher likelihood of joint disorder in the elbow, and prolonged sitting hours result in a 1.60 times higher disability in the past 12 months, with longer working hours leading to a 1.60 times higher likelihood of more significant disorder in the past seven days in the elbow region. 
Regarding the wrist, none of the time points showed a significant difference. 
In the back region, age, standing, and sitting hours contribute significantly to developing disorders and disabilities in the back at different times (Table 3). 
In the lower back region, BMI and standing and sitting hours contribute significantly to developing disorders and disabilities in the lower back, showing significance. 
Generally, age, BMI, work experience, and sitting hours in the thigh region contribute significantly to the development of disorders and disabilities in the thigh. 
In the knee region, age, BMI, working hours, and standing and sitting hours contribute significantly to developing disorders and disabilities. 
In the ankle region, BMI, work experience, and standing hours contribute significantly to developing disorders and disabilities in the ankle. 

Discussion 
According to the study findings, the prevalence of musculoskeletal disorders resulting from work in the past 12 months among female teachers in Damascus was high, with the highest prevalence in the lower back, followed by the neck, shoulder, wrist, knee, ankle, thigh, back, and elbow. Overall, average age, BMI, work experience, working hours, and standing and sitting hours during work are associated with spinal column pain (neck, lower back, and back) and lower limb pain. Individuals with higher age and BMI, longer work experience, and longer standing and sitting hours are more susceptible to musculoskeletal pain. 
The results of this study, in line with Abdel-Salam’s study conducted in Saudi Arabia on school teachers, reported the highest prevalence of musculoskeletal disorders in the lower back, knees, shoulders, neck, and wrists [4]. In this study, the incidence of musculoskeletal disorders had a significant and meaningful positive correlation with age, lack of exercise, teaching experience, and lacking easy and standard teaching equipment [4]. Age and work history were considered active risk factors in our study, indicating a logical association with tissue changes and degradation with increasing age and work experience.
Additionally, it was mentioned in Abdel-Salam’s study that musculoskeletal pains affect teachers more than other professions, especially with inappropriate working conditions, which are more prevalent among female teachers. Furthermore, Moon showed the highest prevalence of musculoskeletal disorders in the lower back, back, neck, wrists, and shoulders [10]. Chong also reported the prevalence of musculoskeletal problems in the lower back, neck, shoulders, and back, consistent with our study [11]. Darwish’s studies also highlighted the highest prevalence of musculoskeletal pains among female teachers, particularly in the lower back region, due to prolonged standing hours in schools and other factors such as improper posture during work and physical unpreparedness [1, 2, 8, 12-16]. In a study by Darwish in Saudi Arabia, like the present study, the most common areas of musculoskeletal problems after the lower back were the neck, shoulders, and wrists [1]. Additionally, Egger reported the highest prevalence of musculoskeletal disorders in the neck, shoulders, and lower back [12], mainly attributed to prolonged neck bending during tasks like questioning, paper correction, reading, and so on, affecting the entire neck and upper body column [1, 17-19]. Risk factors for musculoskeletal pains in this study included age, weight, number of children, footwear type, teaching years, and daily working hours, with some factors like age, weight, and daily working hours also examined in our study with similar results [1].
In the study conducted by Alias et al. in Terengganu, Malaysia, on elementary school teachers, the highest prevalence of musculoskeletal problems was shown in the leg area and the knee, back, and waist areas. Also, the prevalence of these disorders had a significant and positive relationship with risk factors such as age, body mass index, physical activity, type of footwear, working hours, and standing hours [5]. Considering the similar risk factors in our study, it can be concluded that age, working hours, and standing hours, due to prolonged and improper loading on joints and tissue degradation and wear, are predictable factors in pain and musculoskeletal disorders. 
Khanom’s study among teachers in Bangladesh shows the highest prevalence of musculoskeletal disorders in the neck, lower back, shoulders, knees, and ankles. Interestingly, there was no strong correlation between social and demographic factors and general factors like age, sex, type of school, and shoe heel [18]. Conversely, prolonged standing or sitting, writing on the board, bending the neck and back for extended periods, and over-shoulder hand activities were considered risk factors [18]. These results emphasize the importance of proper biomechanics and ergonomics in preventing such issues. In another study by Sethy, which used the standard DASH (Disabilities of the Arm, Shoulder, and Hand) questionnaire to assess the prevalence of musculoskeletal disorders in northern and western cities of India, neck pain was the most common musculoskeletal problem, followed by shoulder, back, wrist, hand, and knee pain in that order [8]. The most common risk factor reported in this study was working with hands above shoulder level [8]. Other risk factors included long-term work postures, especially with head and neck bending, repetitive movements involving wrists and hands, and prolonged standing [8]. Once again, this result emphasizes the importance of biomechanical and ergonomic considerations in preventing and treating these disorders.
Yadav’s study in Delhi, similar to our study using the Nordic questionnaire, reported the knee, ankle, neck, and lower back as the most common areas of injury, with BMI and stress being significant risk factors, especially due to prolonged standing leading to knee pain and prolonged neck bending causing neck problems [17]. 
In a review study conducted by Erick and Smith on the prevalence of musculoskeletal disorders self-reported by various teachers using different questionnaires, it was shown that the prevalence of these disorders among different communities ranged from 39% to 95%, with the most common locations being the lower back, neck, and upper limbs [6]. In general, considering the studies in this field, it can be said that various factors, such as individual characteristics, work-related factors, and socio-psychological issues, play a role in the development of musculoskeletal problems. Age, gender, work history, poor workplace posture, and inappropriate work equipment are considered individual and work-related risk factors [6, 12, 19]. Social-psychological factors include the fact that women are more at risk of musculoskeletal problems due to lower physical strength, family pressure, different job prospects, and pain thresholds compared to men. Individuals with more work experience are more likely to suffer from musculoskeletal pain due to prolonged exposure to occupational risk factors. However, some studies have shown that newly hired young individuals who have not yet adapted to the new work environment and physical and psychological stressors may also be more susceptible to such disorders. Additionally, the contradiction regarding age is evident in studies, as although the risk of musculoskeletal disorders increases with age due to decreased collagen, muscle mass, and connective tissue flexibility, some disorders, such as lower back pain and neck pain, are more common in young individuals who are expected to work more than older individuals [6-8].
Furthermore, some studies have considered psychological factors such as high work pressure, high stress, low social support, low job satisfaction, and monotonous work factors related to musculoskeletal problems [6, 12, 19]. On the other hand, regular physical activity has been considered a protective factor in some studies, as teaching is often perceived as a sedentary job involving long periods of static postures (sitting and standing). In contrast, a sedentary lifestyle is associated with obesity as a significant risk factor. Dragoo found that teachers spend more hours at work due to their contractual conditions, and these extra working hours significantly limit their participation in physical activities and sports [20].

Conclusion 
In conclusion, musculoskeletal disorders and pains are common and multidimensional problems influenced by various factors such as demographic, social, individual characteristics, and work environment. They are more prevalent in individuals with higher weights and ages, lack of exercise, longer work experience, inadequate footwear and teaching equipment, and longer working hours. Therefore, preventive measures such as reducing work pressure, increasing rest hours between classes, especially for older individuals, engaging in regular physical activities and sports, using appropriate footwear, following biomechanical and ergonomic standards, and using suitable job equipment like desks, chairs, and computers with proper height settings can reduce the prevalence of musculoskeletal pain among teachers and control the significant costs imposed on individuals and society in this regard. Government policies and planning to improve teachers’ working conditions are also crucial.
One limitation of this study is that all samples examined in this study were selected from the city of Damascus, so the study’s results cannot be generalized to other cities in Syria, considering their potentially different occupational conditions. Another limitation of the study is the small sample size. Therefore, the results of this study are not widely generalizable. 
It is recommended that future studies on the prevalence of musculoskeletal disorders among teachers and related factors be conducted with a larger sample size in several cities across Syria due to the different conditions in various cities. Clinical examinations and ergonomic assessments should be conducted simultaneously with questionnaires to obtain more accurate results.

Ethical Considerations
Compliance with ethical guidelines
This study was approved by the Ethics Committee of the University of Social Welfare and Rehabilitation Sciences, Tehran, Iran (code: (IR.USWR.REC.1402.109), and the necessary permits were obtained from the Ministry of Education of Syria. After explaining the study objectives to the participants and ensuring their confidentiality, they signed an informed consent form. They were free to leave the study at any time.

Funding
This article was extracted from the master’s thesis of Hossein Alkhodr at the Department of Physiotherapy, University of Social Welfare and Rehabilitation Sciences, Tehran, Iran. This research did not receive any specific grant from funding agencies in the public, commercial, or not-for profit sectors.

Authors' contributions
Conceptualization: Hossein Alkhodr, Samieh Mohammadi, Iradj Abdollahi, and Nooraldin Karimi; Methodology: Hossein Alkhodr, Samieh Mohammadi, Nooraldin Karimi, and Samaneh Hosseinzadeh; Validation, initial draft preparation, resources: Hossein Alkhodr and Samieh Mohammadi; Data analysis: Samaneh Hosseinzadeh; Editing and review: Samieh Mohammadi; Supervision, project management: Samieh Mohammadi, Iradj Abdollahi, and Nooraldin Karimi;Investigation: All authors.

Conflict of interest
The authors declare no conflicts of interest.



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