Key Words: work-related disorders, upper limb, neck musculoskeletal, ergonomic design, training
What effects do workplace ergonomic design or training interventions, or both, have in the prevention of work-related upper limb and neck musculoskeletal disorders (MSD) in adults?
Work-related upper limb and neck MSD are one of the most common occupational disorders around the world. The evidence is unclear as to whether ergonomic design and training is likely to reduce the risk of workers developing work-related upper limb and neck MSD.
This is a summary of a Cochrane Systematic Review containing 13 randomized controlled trials (RCT’s) involving 2,397 workers. Eleven studies were conducted in an office environment and two in a healthcare setting. The participants included adults working at the time of the intervention and who were exposed to risk factors for work-related upper limb musculoskeletal disorders (WRULDs) at their workplace. As the review was focused on prevention of WRULDs, the majority of participants (75% or more) should have been free of WRULDs at the time of the intervention. The included studies examined at least one ergonomic design or training intervention, or both.
Ergonomic design was categorized as:
- Ergonomically designed equipment such as specially designed computer mouse or arm support;
- Ergonomically designed work environment, including workplace and job design;
- Ergonomic training;
- Ergonomic training combined with ergonomic equipment.
The primary outcomes for this review were:
- Number of people with newly diagnosed or verified WRULDs;
- Complaints or symptoms of pain or discomfort in the upper limb or neck, or both; and
- Work-related function
Secondary outcomes included change in productivity, costs and compliance.
The follow-up period ranged from three weeks to 12 months. The risk of bias was judged to be high in 12 of the 13 studies. This was mainly due to the study authors not having blinded participants, personnel, or outcome assessment and because of incomplete outcome data. Meta-analysis was undertaken where possible.
Summary of Key Evidence:
Studies evaluating the effectiveness of ergonomic equipment among computer users (two studies). A meta-analysis of two studies demonstrated using an arm support together with an alternative mouse compared to using a conventional mouse alone significantly decreased the incidence of neck/shoulder disorders (Relative Risk [RR] 0.52; 95% Confidence Interval [CI] 0.27 to 0.99). There was no difference in the incidence of right upper limb or upper body disorders The intervention group also significantly decreased neck/shoulder discomfort scores (Standardized Mean Difference [SMD] –0.41; 95% CI –0.69 to –0.12) and right upper limb discomfort scores (SMD –0.34; 95% CI –0.63 to –0.06) when compared to the control.
There was no difference in the incidence of disorders of the neck/shoulder, right upper limb, or upper body, or discomfort scores for neck/shoulder or right upper limb between using an alternative mouse alone and a conventional mouse alone.
The results comparing arm support with conventional mouse and conventional mouse alone showed that there was no difference in the incidence of disorders of the neck/shoulder right upper limb or upper body and discomfort scores for neck/shoulder or right upper limb.
The results comparing alternative mouse with arm support and conventional mouse with arm support showed no difference in the incidence of disorders of the neck/shoulder, right upper limb, or upper body. The results did show a significant decrease in the discomfort scores for the neck/shoulder (SMD –0.39; 95% CI –0.67 to –0.10) and also a non-significant decrease in the right upper extremity.
Studies evaluating the effectiveness of supplementary breaks or reduced work hours (four studies). Two studies measuring supplementary breaks underwent a meta-analysis demonstrating no differences in the end of the shift discomfort scores for the neck, right shoulder/upper arm and right forearm/wrist/hand.
The results comparing reduced work hours (37.5 hours/week) and normal work hours (40 hours/week) showed that there was no difference in upper-extremity symptoms, pain or work ability at six or 12 months or in productivity.
Studies evaluating the effectiveness of ergonomic training (three studies). The results of only two studies could be reported due to issues with incomplete data and limited follow-up. No significant differences were found in risk for neck-shoulder symptoms or hand-wrist symptoms, intensity, frequency, or duration of upper extremity symptoms.
Studies evaluating the effectiveness of ergonomic training and equipment (one study). No significant differences in frequency of neck, shoulder, or wrist/hand ache or pain, and intensity of neck, shoulder or wrist/hand ache or pain were demonstrated at the end of 16 weeks.
Studies evaluating the effectiveness of lifting interventions (one study). There was no significant difference in shoulder symptoms score. The cost of all injuries and time loss injuries was highest for the control group.
Best Practice Recommendations:
The current available evidence demonstrates moderate-quality evidence to suggest that the use of an arm support together with an alternative mouse may reduce the incidence of neck or shoulder MSDs, but not right upper limb MSDs among Visual Display Unit users. There was moderate-quality evidence to suggest that the incidence of neck or shoulder and right upper limb MSDs is not reduced by using an alternative mouse as compared to a conventional mouse, with and without arm support. High-quality evidence is needed to clearly determine the effectiveness of all these interventions.
A member of the Cochrane Nursing Care Field (CNCF)
Hoe, V. C. W., Urquhart, D. M., Kelsall, H. L., & Sim, M. R. (2012). Ergonomic design and training for preventing work-related musculoskeletal disorders of the upper limb and neck in adults. Cochrane Database of Systematic Reviews 2012, 8. Art No.: CD008570. DOI: 10.1002/14651858.CD008570.pub2. http://onlinelibrary.wiley.com/doi/10.1002/14651858.CD008570.pub2/abstract