A literature review of the effects of computer input device design on biomechanical loading and musculoskeletal outcomes during computer work

Prevalence of low back pain and its associated factors among traditional cloth weavers in Gulele sub-city, Addis Ababa, Ethiopia

The prevalence of work-related musculoskeletal disorders particularly low back pain is significantly high among common informal or small-scale enterprises within developing countries like weaving. However, there is little information on risk factors for low back pain in the informal sector such as the weaving sector in the areas of Addis Ababa as well as in Ethiopia. Therefore this study was aimed to assess the magnitude of low back pain and its associated factors among traditional cloth weavers in the Gulele sub-city, Addis Ababa, Ethiopia. A cross-sectional study with internal comparison was conducted from June 1, 2022, and August 30, 2022. A total of 660 traditional cloth weavers were included in the study by using a systematic random sampling method to select participants in each of cooperatives as well as individual households in 5 woredas in Gulele sub-city. The data was analyzed and managed using SPSS version 20. A multivariate logistic regression analysis was used to control potential confounding factors and to determine the association. Among 660 (100%) respondents, 330 (50%) of them experienced low back pain after starting weaving. Out of the respondents with low back pain through their job career, 291 (44.1%) of them experienced low back pain during the last 12 months. Working greater than 8 h per day (AOR = 4.60, 95%CI: 2.35, 8.87), working with frequent bending (AOR = 3.32, 95%CI: 1.49, 7.40), job stress (AOR = 1.68, 95%CI: 1.18, 2.40) were among factors significantly associated with the occurrence of low back pain. This study has shown a high prevalence of low back pain among traditional cloth weavers which indicates the need for immediate public health action. However, very small improvements in the working condition, weaving tools design, working methods can potentially lead to large benefits.

The Effects of Standing Working Posture on Operation Force and Upper Limb Muscle Activation When Using Different Pointing Devices

This study investigated how sitting and standing working postures affected operation force, upper limb muscle activation, and task performance using different pointing devices. Fifteen male participants completed cursor aiming and dragging tasks using a conventional mouse, a vertical mouse, and a trackball at sitting and standing workstations. A custom-made force plate was used to measure operation forces applied to the pointing devices. Surface electromyography (EMG) was used to capture the activation of the biceps brachii, triceps brachii, deltoid, and trapezius. Task performance was measured by task success rates, and subjective ratings were obtained for the force required for operation, smoothness of operation, accuracy, and local fatigue in the upper limb. We quantified the following significant outcomes: (1) greater operation forces were found when standing; (2) standing reduced EMG amplitudes of the triceps and trapezius muscles for all tasks; (3) during the aiming task, the vertical mouse had greater operation forces; (4) during the dragging task, both the vertical mouse and trackball had greater operation forces; and (5) task success rates differed for pointing devices only when sitting. This study revealed the distinct biomechanical properties of standing working posture and suggested limited beneficial effects of alternative pointing devices in terms of task performance and subjective ratings.

Time to re-think our strategy with musculoskeletal disorders and workstation ergonomics

Background

The dramatic increase in visual display units (VDU) in the workplace over a 20-year period is linked to the increased prevalence of musculoskeletal disorders (MSDs).

Objectives

The objective of our study was to compare ergonomic risk factors and work-related psychosocial factors in VDU users with and without MSD.

Methods

Participants, with and without MSD, working with VDU for more than 4 h a day completed the Nordic Musculoskeletal Questionnaire and the Effort-Reward Imbalance Model and Over-commitment Questionnaire. The workstation of each participant was assessed for ergonomic risk factors using the Rapid Office Strain Assessment (ROSA).

Results

Sixty-eight VDU users with and 68 without MSDs participated. The workstation ergonomic risk factors as measured with the ROSA were similar for the two groups: 4.5 ± 1.0 for the MSD group and 4.3 ± 0.8 for the reference group (p = 0.10). The work-related psychosocial factors, namely over-commitment, were higher in the MSD group (14.9 ± 3.1) than in the reference group (13.8 ± 3.4; p = 0.041).

Conclusions

As over-commitment is an indication of intrinsic factors and personal characteristics, the significant difference between the MSD group’s over-commitment score and that of the reference group suggests that interventions to empower individuals are needed.

Clinical implications

Physiotherapists should only adjust ergonomic workstation risk factors when established as contributory to MSD, and should be cognisant of work-related or individual psychosocial factors that may impact the patient with MSD. The use of ergonomic advice to patients with MSD should be performed with caution, taking all the work place risk factors for MSD into account.

Changes in the Sagittal Cranio-Cervical Posture Following a 12-Week Intervention Using a Simple Spinal Traction Device

STUDY DESIGN

Non-controlled clinical trial.

OBJECTIVE

To assess the efficacy of a simple home spinal traction device on sagittal cranio-cervical posture and related symptoms.

SUMMARY OF BACKGROUND DATA

Forward head protraction (FHP) and cranio-cervical malalignment were shown to be consequential in the development adverse musculoskeletal radiographic findings and symptoms in that region.

METHODS

Participants (n = 13, 18-36-year-old) were drawn from a mildly symptomatic population, all presented with cranio-cervical malalignment and considerable FHP. Participants used a simple home spinal traction device for 12 weeks, 10 min/d. Sagittal cervical radiographs and the SF36 health survey were obtained pre/post intervention and guideline compliance was recorded. Radiographic evaluation included typical measurements of sagittal cranio-cervical alignment and FHP (e.g., atlas plane line, vertical axis line, sagittal cranial angle, absolute rotation angle). Standard paired samples t tests, chi-squared, and effect size analyses were used to assess pre- and post-intervention changes.

RESULTS

Each of the key radiographic variables recorded significant moderate to very large positive changes as a result of the intervention. Similarly, Chi-squared analyses indicated that saggital cervical spine configuration tended to become more lordotic (P = 0.007), with four participants shifting from a kyphotic to a lordotic presentation. SF36 health survey data demonstrated mostly significant positive changes throughout all tested domains, and moderate positive changes were recorded across all radiographic cranio-cervical mesured paramenters (e.g., decreased FHP, increased cervical lordosis, and cranial extention). Participants indicated high level of protocol compliance.

CONCLUSION

This study has demonstrated that the unsupervised daily use of a simple home spinal traction device (Thoracic Pillow) proved effective in bringing positive plastic changes to the sagittal cranio-cervical alignment and reduction in symptoms in the tested population during a short intervention period.

LEVEL OF EVIDENCE

3.

Posture and discomfort assessment in computer users while using touch screen device as compared with mouse-keyboard and touch pad-keyboard

BACKGROUND

Touch screen computers require significant arm and hand movements. This can result to body discomfort and biomechanical load in users.

OBJECTIVES

This study was carried out to examine posture and users' discomfort while using touch screen device as compared with mouse-keyboard and touch pad-keyboard.

METHODS

Twenty three (23) students participated in this experimental study. The subjects completed pre-defined tasks in three 15 min trials by means of touch screen, touch pad-keyboard and mouse-keyboard as input devices. Postural angles were measured by Qualisys motion capture system. Body discomfort was assessed by a 10-cm visual analog scale. Rating scale was employed to assess the perception of subjects on the posture of body parts while utilizing the three devices.

RESULTS

There was no significant difference in head inclination when using the three types of devices. Nevertheless, the mean of neck (p = 0.005) and trunk (p < 0.0001) inclinations as well as arm angle (p < 0.0001) while using touch screen, differed significantly from the two other devices and were more deviated from neutral posture. The type of input device was found to have significant effect on the right shoulder (p = 0.017), right elbow (p = 0.031), right wrist/hand (p = 0.004) and whole body discomfort (p = 0.026). Touch screen caused more discomfort in the mentioned regions when compared to the other two devices. Friedman test showed that differences of mean ratings for perceived shoulder and elbow postures in the 3 trials were significant (p = 0.005 and p = 0.011, respectively). Touch screen was the most unfavorable input device based on the subjects' judgment.

CONCLUSION

Touch screen caused more deviated postural angles, increased body discomfort and unfavorable postures.