Ergonomic and psychosocial risk factors associated with work-related musculoskeletal disorders in Mohs histotechs

Abstract

Mohs histotechs are at high risk for work-related musculoskeletal disorders (WRMSDs) due to repetitive motions, forceful exertions, and fixed postures required for their work. Psychosocial factors such as perceptions of pressure to achieve deadlines may exacerbate risk of occupational injury. To assess the prevalence of and risk factors for WRMSD in Mohs histotechs, an online survey was created using literature review, expert opinion, and two validated instruments (the Nordic Musculoskeletal Questionnaire and the Oldenburg Burnout Inventory) and distributed to Mohs histotechs. 88% of respondents reported musculoskeletal problems in 2 or more of the 9 body sites assessed in the past year. Standing during specimen processing was correlated with having neck pain and upper back pain, while sitting was protective against lower back pain. Individuals that felt that they could not take breaks or slow their pace of work were more likely to report pain at multiple body sites. Total pain scores were significantly lower in those reporting extensive ergonomic training. There is a high prevalence of WRMSD in Mohs histotechs. Addressing poor posture as well as psychosocial risk factors could further reduce injury.

Introduction

Work-related musculoskeletal disorders (WRMSDs) can cause chronic pain and disability, leading to decreased productivity and absenteeism in the workforce [1]. Laboratory workers are at risk for developing WRMSDs due to chronic microtrauma sustained from performing repetitive, fine motor tasks for extended periods of time as well as holding static, non-ergonomic postures while using lab equipment such as the cryostat or microscope [2–6]. Several studies from America [7], Europe [8], Australia [1], Africa [3], and the Middle East [9] have established the high prevalence (40–80%) of WRMSDs in laboratory professionals, namely technicians, pathologists, and trainees. However, there is a lack of data about musculoskeletal problems and risk factors in the Mohs laboratory.

Mohs histology technicians and technologists, henceforth referred to as histotechs, play a vital role in the patient care delivered by Mohs micrographic surgeons. Routine tasks performed for each surgical case include grossing, embedding, cutting, staining, and mounting tissue. Mohs histotechs are challenged to perform these tasks expeditiously as patients wait in the clinic until all surgical margins are clear of carcinoma. Therefore, this group is at high risk for WRMSDs due to repetitive motions, forceful exertions, and fixed postures required for their work. Psychosocial risk factors such as perceptions of pressure to achieve deadlines and feeling unable to take breaks may increase their risk of injury.

The primary aim of this study is to investigate the prevalence and anatomic sites of WRMSDs affecting Mohs histotechs. Our survey-based study characterizes the postures, movements, and psychosocial factors that contribute to these injuries. These findings are essential for creating educational programming and intervention strategies to reduce WRMSDs in this group. A secondary aim of this study is to identify poor ergonomic behaviors and develop recommendations to reduce the risk for workplace injury.

Methods

This was an internet survey-based cross-sectional evaluation of ergonomic and psychosocial risk factors associated with WRMSDs in Mohs histotechs in the USA. Members of the American Society of Mohs Histotechnology (ASMH) were asked 91 questions using a combination of the literature review and expert opinion, as well as two validated survey instruments: the standardized Nordic Musculoskeletal Questionnaire (NMQ) and the Oldenburg Burnout Inventory (OLBI). The survey was approved and distributed via email by the ASMH. Information about demographics, work history, and organizational structure was also collected.

The NMQ is a validated tool that is used to assess the prevalence of occupational musculoskeletal symptoms across many workplace settings [10]. It is composed of 40 forced-choice items that identify musculoskeletal symptoms (ache, pain, discomfort, or numbness) in nine key body areas: neck, shoulders, upper back, elbows, wrists/hands, lower back, hips/thighs, knees, and ankles/feet within the last 12 months. If respondents replied that they had experienced symptoms in the last year, they were prompted to answer whether they had seen a physician for the symptoms and if they experienced the symptoms in the past 7 days. In addition to the NMQ, a summary measure of reported pain in the past year was created by summing each respondent’s evaluation of pain for the nine anatomic location categories. The resulting pain summary measure has a range from 0 to 9. The OLBI is a 16-item survey aimed to measure burnout in the workplace [11]. Questions are both positively and negatively framed and measure the participants level of exhaustion and disengagement from work on a scale of 1–4. The burnout score is calculated by adding scores for each question—the higher the score, the greater the level of burnout. There is currently no consensus on which numerical scores correlate with low, medium, or high levels of burnout.

Descriptive and relative frequencies, means, and associated standard deviations, along with graphical methods were used to assess the distribution survey responses. To evaluate possible associations between pain in specific anatomic locations and workflow characteristics, univariate logistic regression analysis was used. In these analyses, the presence or absence of pain at each specific anatomic location was the outcome variable and inability to slow the pace of work, and inability to have defined breaks during the workday were the independent variables. Multinomial logistic regression was used to evaluate the association between working position (sitting, standing, and combination of sitting and standing) and the summary pain measure. Results of these analyses are presented as odds ratios along with 95% confidence intervals. All analyses were performed using Stata, version 16.1, Stata Corporation, College Station, TX, USA.

Following completion of the internet-based survey, a professional ergonomist conducted an ergonomic risk assessment of four histotechs at our institution. The goal was to identify ergonomic risk factors and provide recommendations to histotechs to reduce the risk WRMSDs.

Results

A total of 121 Mohs histotechs from across the USA completed the survey. The approximate response rate was 30%. Most respondents were women (79.3%) with a mean age 47.2 years (range 25–70 years). The average body mass index (BMI) was 28.4 (range 17.5–46.1). Over 70% of participants reported that they regularly exercised at least 1–2 times per week. Less than 50% of participants reported prior non-work-related musculoskeletal injuries (Table 1).

Table 1.

Demographics of survey respondents

Demographics
Age, mean (SD)	47.2 (11.6)
Gender, n (%) Male	25 (20.7)
Female	96 (79.3)
BMI, mean (SD)	28.4 (5.9)
Exercise frequency, n (%)
Not currently	1 (0.8)
Never	14 (11.6)
2–3 times per month	19 (15.7)
1–2 times per week	34 (28.1)
3–4 times per week	38 (31.4)
5 times per week	1 (0.8)
Daily	14 (11.6
History of non-work-related injury, n (%)
No	73 (60.3)
Yes, in the distant past	36 (29.8)
Yes, in the recent past	12 (9.9)

Respondents reported working as Mohs histotechs for an average of 12.3 years (min/max: 0.5–31 years) and over 50% of surveyed individuals were either currently or previously employed as lab technicians outside of the Mohs setting. Routine Mohs laboratory tasks included accessioning, grossing, embedding, staining, and sectioning tissue. Automatic slide stainers were used by over 75% of participants. Respondents reported that these tasks were typically performed at independent workbenches and most study participants did not have to accommodate another histotech at their workstation. Sixty percent of participants reported standing while working. Most histotechs reported a daily case workload of 5–10 cases per day, producing 21–30 slides per day (Table 2). Only 42% of surveyed histotechs received at least some ergonomic training and less than 40% reported that ergonomics was considered when purchasing lab equipment.

Table 2.

Work history of survey respondents

Work history
Years as a Mohs technician, mean (SD)	12.3 (8.1)
Years as a lab technician outside of Mohs	10.2 (8.6)
Cases done per day, n (%)
1–4 cases	6 (5)
5–10 cases	60 (49.6)
11–15 cases	38 (31.4)
16–20 cases	13 (10.7)
21–25 cases	2 (1.7)
> 26 cases	2 (1.7)
Slides produced per day, n (%)
1–10 slides	2 (1.7)
11–20 slides	26 (21.5)
31–40 slides	23 (19)
41–50 slides	9 (7.4)
> 50 slides	13 (10.7)
Position while working, n (%)
Mostly stand	73 (60.3)
Mostly sit	48 (39.7)
Ergonomic training in workplace, n (%)
No	70 (57.9)
Yes, some	41 (33.9)
Yes, extensive	10 (8.3)

Overall, 88% of respondents reported musculoskeletal trouble in two or more of the nine body areas in the last 12 months. The body areas with the highest prevalence of problems in the last 12 months were the neck (76%), shoulder (61.1%), and lower back (61.1%). About half of participants reported active problems (defined as problems within the last 7 days) in at least one body site at the time of the survey. The shoulder and neck were the most prevalent anatomic sites for active problems (36 and 34.7%). While many participants reported either ache, pain, discomfort, or numbness in these areas, most injuries did not impact the participants ability to complete normal activities but over 60% reported regularly taking medications to manage pain to continue working. Despite this, a minority sought medical attention for these problems (Fig. 1).

Fig. 1.

Musculoskeletal problems in Mohs histotechs by anatomic site

Total pain scores were not associated with participant age, BMI, number of daily cases, or total years worked as a Mohs histotech. Lower back pain was positively associated with number of slides produced per day (OR 1.5, p = 0.045). Pain scores were significantly lower in those that reported extensive ergonomic training (Fig. 2) and those who performed tasks in the seated position (Fig. 3). From a multinomial logistic model, for every 1-point increase in the total pain score, respondents were 20% more likely to report “only standing” during specimen grossing, embedding, and sectioning compared to those who reported both “sitting and standing” for these tasks. Standing during specimen grossing, embedding, and sectioning was also associated with reported neck pain (OR 3.0, p = 0.057) and upper back pain (OR 2.5, p = 0.028). Sitting was protective against reported lower back pain (OR 0.3, p = 0.031). Participants that felt that they could not take breaks (54.6%) or slow their pace of work (66.9%) were more likely to have pain at multiple body sites (Table 3).

Fig. 2.

Boxplot of total pain scores based on workplace ergonomic training. Total pain scores were lower in those that received extensive ergonomic training. *p = 0.833 for the difference mean values of total pain score between those who report ‘no training’ versus ‘yes—some training’ in ergonomics. **p < 0.001 for the difference mean values of total pain score between those who report ‘no training’ versus ‘yes— extensive training’in ergonomics

Fig. 3.

Boxplot of total pain scores by whether the respondent sits, sits and stands, or stands while grossing specimens, embedding tissue, and using the cryostat. Total pain scores were the lowest in individuals that mostly sit while performing work tasks. *p = 0.125 for the difference mean values of total pain score between those who report ‘sitting’ versus ‘sitting and standing’ while performing work tasks. **p = 0.017 for the difference mean values of total pain score between those who report ‘sitting’ versus ‘standing’ while performing work tasks

Table 3.

Univariate logistic regression analyses of reported pain in the past year for each anatomic location based on whether the respondent reported an inability to take breaks during the workday or whether the respondent reported not feeling they could slow the pace of work

Anatomic location	Breaks during the day		p value	Pace of work		p value
	Enough time for breaks	Not enough time for breaks		Able to slow pace of work	Unable to slow pace of work
	OR	OR (95% CI)		OR	OR (95% CI)
Neck	1.0 (referent)	3.6 (1.5–8.8)	0.005	1.0 (referent)	3.5 (1.5–8.3)	0.005
Shoulder	1.0 (referent)	2.2 (1.1–4.7)	0.036	1.0 (referent)	3.8 (1.7–8.4)	0.001
Upper back	1.0 (referent)	1.6 (0.8–3.3)	0.185	1.0 (referent)	2.4 (1.1–5.3)	0.026
Elbows	1.0 (referent)	3.3 (1.2–9.0)	0.019	1.0 (referent)	4.6 (1.3—16.4)	0.019
Hands	1.0 (referent)	3.0 (1.4–6.3)	0.004	1.0 (referent)	2.5 (1.1–5.5)	0.025
Lower back	1.0 (referent)	2.2 (1.1–4.7)	0.036	1.0 (referent)	1.5 (0.7–3.2)	0.330
Hips/thighs	1.0 (referent)	2.3 (1.1–5.0)	0.036	1.0 (referent)	2.5 (1.1–5.9)	0.038
Knees	1.0 (referent)	1.4 (0.7–3.1)	0.372	1.0 (referent)	1.3 (0.6–3.0)	0.516
Ankles/feet	1.0 (referent)	1.8 (0.8–3.9)	0.147	1.0 (referent)	1.4 (0.6–3.2)	0.435

A formal ergonomic assessment of four Mohs histotechs identified multiple modifiable risks that led to poor workplace ergonomics. These factors can be grouped into two primary categories: static awkward postures and contact stress. Vertical and lateral neck flexion and trunk flexion > 20° was observed while histotechs were viewing tissue samples and working at the cryostat. Upper arm flexion > 20° with shoulder abduction was noted when operating the cryostat handle. Finally, wrist flexion/extension with ulnar or radial deviation occurred frequently when manipulating specimens and slides. Contact stress, defined as prolonged contact between a body part and a hard or sharp object, occurred when histotechs rested forearms on the cryostat while cutting tissue. The validated Rapid Entire Body Assessment (REBA) score [12] of Mohs histotechs was 10 (out of a maximum score of 15), indicating very high risk of musculoskeletal disorders in the Mohs lab. This real-world assessment characterized risk behaviors that corresponded to the problem areas identified by survey respondents. Furthermore, it uncovers the potential to reduce WRMSDs among histotechs.

Discussion

Mohs histotechs are at risk for WRMSDs due to specific static postures and fine motor movements required in their work. This study confirms the high prevalence (88%) of WRMSDs in Mohs histotechs, as well as risk factors that contribute to these injuries. The anatomic sites with the highest rates of reported musculoskeletal problems in the preceding 12 months were the neck, lower back, and shoulder. Furthermore, the neck and shoulder were the highest reported sites of active musculoskeletal problems. Sixty percent of participants reported taking medications to alleviate pain to continue with work, signifying an immense need for ergonomic occupational safety intervention in this group to reduce sick days and preserve career longevity. Our findings are consistent with published research [1, 2, 7–9, 13, 14] of laboratory technicians and pathologists outside of the Mohs setting likely due to analogous workstation setup and non-ergonomic work habits. We found that age, sex, BMI, years of laboratory experience, and daily case load did not correlate with the degree of reported musculoskeletal problems. However, respondents that produced a higher number of slides trended toward having higher lower back pain scores. Therefore, the number of slides produced may be a better indicator of work volume than case load and increased sectioning and use of the cryostat may contribute to lower back WRMSDs.

Our results differed from published literature with regard to the impact of sex, age, and years in practice on the prevalence of WRMSDs. Two prior studies of laboratory workers [8, 9] concluded that female sex correlated with high WRMSDs reported; however, this was not corroborated in our study. As both studies were conducted outside of the USA, population differences such as relative muscle mass and BMI, as well as non-occupational factors such as gender balance of domestic work may have contributed to the differing results. Furthermore, Mohs histotechs primarily perform repetitive fine motor movements rather than gross motor movements so the physiological differences in muscle strength between sexes play less of a role in the susceptibility to musculoskeletal injury in this specific cohort. Early ergonomics literature in laboratory workers [3] suggests that age and years in practice are directly correlated to prevalence of musculoskeletal disorders. Our study, as well as contemporary studies in lab technicians [1, 13] and Mohs surgeons [15] found no association between these demographic factors and WRMSD. WRMSD can develop early in a histotechs career; therefore, ergonomic education should occur in training and ergonomic work habits should be reinforced throughout the career. Taken together, these findings suggest that the laboratory environment, much of which is modifiable, contributes significantly to musculoskeletal problems in Mohs histotechs.

Participants in our study that reported mainly standing while working had higher pain scores compared to those who reported a combination of sitting and standing. Interestingly, those who reported sitting all day had lower total pain scores than those who reported a combination of sitting and standing, although this finding was not statistically significant. Studies conducted in other medical specialties such as surgery (including Mohs surgery), dentistry, and radiology suggest that any static axial skeleton posture, whether sitting or standing, can lead to WRMSDs [16]. Most ergonomic literature recommends alternating between sitting and standing working positions to reduce static postures that are known to contribute significantly to neck and back pain. Maintaining a neutral spine through the use of adjustable chairs, stools, tables, and ergonomic microscopes is paramount in reducing musculoskeletal strain [1–3, 6, 13, 16].

When comparing our results to two prior survey-based studies of Mohs surgeons [15–17], we found many parallels in WRMSD between Mohs surgeons and Mohs histotechs. The prevalence of musculoskeletal symptoms or pain was 90% in surveyed Mohs surgeons and the most common sites of injury in Mohs surgeons were also the neck, lower back, and shoulder [15, 17]. About half of surveyed surgeons reported receiving medical attention for these musculoskeletal issues and a small percentage reported that WRMSD interfered with activities of daily living [15]. These commonalities suggest that similar ergonomic hazards exist in the operating suite and the histotechnology lab. Holding static postures at angles greater than 20° is one major modifiable risk behavior for WRMSDs that is observed in Mohs surgeons performing surgery and Mohs histotechs processing tissue in the laboratory [13, 16, 17]. Maintaining neck flexion and trunk flexion angles of less than 15° while operating and processing tissue can significantly reduce injury to the neck and lower back (Fig. 4). This can be accomplished by performing tasks seated on stools with sternal support, or by using magnifying loupes [15–17]. As with Mohs histotechs, Mohs surgeons had limited ergonomic education and evaluation of their workspace and habits [15].

Fig. 4.

Recommended posture (A) and grip (B) to reduce WRMSDs when operating cryostat.

Psychosocial factors such as lack of adequate break time and inability to slow the pace of work also significantly increased the risk WRMSD among Mohs histotechs in this study. Additionally, a 2010 survey of Mohs surgeons reported that Mohs surgeons likewise place immense pressure on themselves and working in a way that contributed to pain in order to complete daily work tasks [15]. Addressing these issues as a practice, through wellness interventions and microbreaks, could further reduce musculoskeletal injury in both Mohs surgeons and histotechs. Microbreaks are scheduled rest breaks that are less than 2 min long and may include light stretching. Despite their short duration, they can be effective in providing relief for a specific set of muscles that are engaged during repetitive tasks or static postures.

Extensive ergonomic training was protective against WRMSDs in our cohort. A recent systematic review of education for management of WRMSD demonstrated that ergonomic training may positively influence musculoskeletal pain. However, the optimal content, timing, and delivery of educational material remains to be elucidated [18]. Other interventions that may improve occupational safety in the Mohs lab include adjusting workstation design, purchasing ergonomic equipment, and workplace strength training [19]. For precision work, such as that performed by Mohs histotechs, workbench height or seat height can be pneumatically adjusted to allow for horizontal thighs, vertical lower legs, feet flat on the ground, and a 90° angle at the elbows. Ergonomic microscopes that reduce the need for forward-leaning posture may be employed [6, 16]. Padding at the cryostat can reduce exposure to contact stress. It is essential, however, that ergonomic intervention include both optimized workstation/equipment design and behavior modification as pain may persist if only one component is addressed [15]. While cost may be perceived as the limiting factor, most Mohs surgeons cited that they did not use or purchase ergonomic equipment due to lack of awareness. Only 8% reported cost as a concern [15].

Limitations of this study include retrospective survey-based design. Respondents self-reported musculoskeletal issues, which has the potential for recall bias. The response rate was relatively low, approximately 30%. Therefore, this study may in fact overestimate the prevalence of WRMSDs in this population as it is possible that technicians experiencing musculoskeletal issues were more likely to respond. Lastly, since no comparator group was used it is difficult to conclude whether all reported musculoskeletal issues in this cohort can be fully attributed to the workplace.

This study draws attention to the high level of WRMSDs in Mohs histotechs. Furthermore, our ergonomic assessment highlights the risks in Mohs laboratory design and equipment, as well as specific postures and methods technicians use to perform tasks. The results emphasize the importance of early ergonomic education in histotech training as well as continued ergonomic optimization throughout a technician’s career. Mohs surgeons and practice managers can systematically evaluate the ergonomic risks in their lab and among their histotechs with validated tools such as the Quick Exposure Checklist [20] and the Rapid Entire Body Assessment [12, 21]. Future studies are needed to better characterize the specific tasks and behaviors that are high-risk for musculoskeletal injury, as well as develop formal best practices to improve ergonomic design of the Mohs histotechnology lab.