Grace P.Y. Szeto

A field comparison of neck and shoulder postures in symptomatic and asymptomatic office workers

Poor neck and shoulder postures have been suggested to be a cause of neck and shoulder pain in computer workers. The present study aimed to evaluate and compare the head, neck and shoulder postures of office workers with and without symptoms in these regions, in their actual work environments. The two all female subject groups reported significantly different discomfort scores across five trials repeated in a single working day. The results of repeated video capture and two-dimensional motion analysis showed that there were trends for increased head tilt and neck flexion postures in the symptomatic subjects (n = 8), compared to the asymptomatic subjects (n = 8). Symptomatic subjects also tended to have more protracted acromions compared with asymptomatic subjects and showed greater movement excursions in the head segment and the acromion. All subjects demonstrated an approximately 10% increase in forward head posture from their relaxed sitting postures when working with the computer display, but there were no significant changes in posture as a result of time-at-work.

A comparison of muscle activity in using touchscreen smartphone among young people with and without chronic neck-shoulder pain

This study aimed to examine differences in muscle activity between young people with and without neck–shoulder pain (n = 20 in each group), when they performed texting on a smartphone. Texting was compared between using both hands (‘bilateral texting’) and with only one hand (‘unilateral texting’). Texting tasks were also compared with computer typing. Surface electromyography from three proximal postural muscles and four distal hand/thumb muscles on the right side was recorded. Compared with healthy controls, young people with neck–shoulder pain showed altered motor control consisting of higher muscle activity in the cervical erector spinae and upper trapezius when performing texting and typing tasks. Generally, unilateral texting was associated with higher muscle loading compared with bilateral texting especially in the forearm muscles. Compared with computer typing, smartphone texting was associated with higher activity in neck extensor and thumb muscles but lower activity in upper and lower trapezius as well as wrist extensors. Practitioner Summary: This study demonstrated that symptomatic individuals had increased muscle activity in the neck–shoulder region when texting on a smartphone. Contemporary ergonomic guidelines should include advice on how to interact with handheld electronic devices to achieve a relaxed posture and reduced muscle load in order to reduce the risk of musculoskeletal disorders.

A study of surgeons’ postural muscle activity during open, laparoscopic, and endovascular surgery

BackgroundDifferent surgical procedures impose different physical demands on surgeons and high prevalence rates of neck and shoulder pain have been reported among general surgeons. Past research has examined electromyography in surgeons mainly during simulated conditions of laparoscopic and open surgery but not during real-time operations and not for long durations. The present study compares the neck-shoulder muscle activities in three types of surgery and between different surgeons. The relationships of postural muscle activities to musculoskeletal symptoms and personal factors also are examined.MethodsTwenty-five surgeons participated in the study (23 men). Surface electromyography (EMG) was recorded in the bilateral cervical erector spinae, upper trapezius, and anterior deltoid muscles during three types of surgical procedures: open, laparoscopic, and endovascular. In each procedure, EMG data were captured for 30 min to more than 1 h. The surgeons were asked to rate any musculoskeletal symptoms before and after surgery.ResultsThe present study showed significantly higher muscle activities in the cervical erector spinae and upper trapezius muscles in open surgery compared with endovascular and laparoscopic procedures. Muscle activities were fairly similar between endovascular and laparoscopic surgery. The upper trapezius usually has an important role in stabilizing both the neck and upper limb posture, and this muscle also recorded higher activities in open compared with laparoscopic and endovascular surgeries. Surgeons reported similar degrees of musculoskeletal symptoms in open and laparoscopic surgeries, which were higher than endovascular surgery.ConclusionsThe present study showed that open surgery imposed significantly greater physical demands on the neck muscles compared with endovascular and laparoscopic surgeries. This may be due to the lighter manual task demands of these minimally invasive surgeries compared with open procedures, which generally required more dynamic movements and more forceful exertions.

Prevalence of work-related musculoskeletal symptoms of the neck and upper extremity among dentists in China

Objectives Studies from western countries show that dentists are vulnerable to work-related musculoskeletal disorders (WMSDs) of the neck and upper extremities, but little is known about their epidemiology among members of this rapidly growing profession in China. This study aims to investigate the prevalence of WMSDs and identify potential risk factors associated with their occurrence in the dental profession in China. Setting and participants A cross-sectional survey was carried out in 52 different hospitals in a large metropolitan city in China. A total of 304 questionnaires were distributed to respondents identified via stratified random sampling and 272 dentists (121 females and 151 males) completed the survey. The response rate was 89.5%. Outcomes Visual analogue score was used to record neck and upper limb musculoskeletal symptoms on a body chart. Work-related risk factors, including physical and psychosocial factors, were accounted for in the regression analysis. Results 88% of the dentists reported at least one musculoskeletal disorder and 83.8% suffered from neck pain. In the multivariate analyses, working hours per day were associated with neck pain (OR=1.43; 95% CI 1.03 to 1.98). Inability to select the appropriate size of dental instrument was associated with shoulder (OR=2.07; 95% CI 1.00 to 4.32) and wrist/hand (OR=2.47; 95% CI 1.15 to 5.32) pain. As for psychosocial factors, high job demand was associated with symptoms in the shoulder (OR=1.09; 95% CI 1.00 to 1.18), elbow (OR=1.11; 95% CI 1.03 to 1.19) and wrist/hand (OR=1.09; 95% CI 1.02 to 1.17). Regular physical exercise was associated with decreased neck pain (OR=0.37; 95% CI 0.14 to 1.00). Conclusions The prevalence of WMSDs among Chinese dentists is high. Specifically, long working hours, inability to select the appropriate size of dental instrument and high job demand are the most significant risk factors.

Normal kinematics of the neck: The interplay between the cervical and thoracic spines

The movement coordination between the cervical and thoracic spine was examined in 34 asymptomatic participants (24 female and 10 male). Three-dimensional electromagnetic motion sensors were attached to the skin overlying the head, T1, T6, and T12 spinous processes to measure the angular displacement of the cervical, upper thoracic, and lower thoracic spine during active neck movements. These displacement measurements were found to have excellent reliability, with intraclass correlation coefficient ranging from 0.899 to 0.993. The angular displacement-time curves of the cervical and upper thoracic spine were also highly repeatable, with coefficient of multiple determinations ranging from 0.900 to 0.967. Both the cervical and thoracic spines were found to contribute to active neck motion, the greatest contribution being from the cervical region in all movement directions. The inter-regional movement coordination between the cervical spine and upper thoracic spine in all three planes of movement was found to be high, as determined by cross-correlation analysis of the movements of the regions. The current results suggest that the motion of the thoracic spine, in particular the upper thoracic spine, contributes to neck mobility, and that the upper thoracic spine should be included during clinical examination of neck dysfunction.

Altered spinal kinematics and muscle recruitment pattern of the cervical and thoracic spine in people with chronic neck pain during functional task

Knowledge on the spinal kinematics and muscle activation of the cervical and thoracic spine during functional task would add to our understanding of the performance and interplay of these spinal regions during dynamic condition. The purpose of this study was to examine the influence of chronic neck pain on the three-dimensional kinematics and muscle recruitment pattern of the cervical and thoracic spine during an overhead reaching task involving a light weight transfer by the upper limb. Synchronized measurements of the three-dimensional spinal kinematics and electromyographic activities of cervical and thoracic spine were acquired in thirty individuals with chronic neck pain and thirty age- and gender-matched asymptomatic controls. Neck pain group showed a significantly decreased cervical velocity and acceleration while performing the task. They also displayed with a predominantly prolonged coactivation of cervical and thoracic muscles throughout the task cycle. The current findings highlighted the importance to examine differential kinematic variables of the spine which are associated with changes in the muscle recruitment in people with chronic neck pain. The results also provide an insight to the appropriate clinical intervention to promote the recovery of the functional disability commonly reported in patients with neck pain disorders.

A study of forearm muscle activity and wrist kinematics in symptomatic office workers performing mouse-clicking tasks with different precision and speed demands

The present study examined various biomechanical parameters in symptomatic and asymptomatic computer users during mouse-clicking tasks with different speed and precision demands. Surface electromyography (EMG) of right wrist flexors and extensors were compared between individuals with computer-related wrist/hand symptoms (n=9) and pain-free controls (n=8). Each subject performed four mouse tasks with high and low precision, constant and fastest speed of 5 min each. Results showed that Case subjects recorded significantly lower EMG amplitudes during maximum voluntary contractions in three out of four forearm muscles (p=0.001-0.019). Normalised median amplitudes of extensor carpi radialis and flexor carpi ulnaris showed significant differences between groups in the speed conditions (p=0.01, 0.04, respectively). Case subjects reported significant discomforts in the wrist/hand region in all tasks, while recorded significantly longer response time and fewer mouse clicks compared to controls. Results suggested that forearm muscles in symptomatic individuals were inhibited in their maximal activation as well as during functional tasks, and this may imply altered motor control mechanisms in forearm muscles contributing to work-related musculoskeletal disorders.

A Comparison of Wrist Posture and Forearm Muscle Activities While Using an Alternative Keyboard and a Standard Keyboard

The wrist posture associated with the use of the conventional “QWERTY” keyboard is a risk factor for work-related musculoskeletal disorders in the upper limbs. Newly designed keyboards have been produced with the aim to reduce the strain in the wrist and forearm region. The present study compared the effects of using a standard keyboard and a split/angled keyboard on the forearm muscle activities and wrist joint angles. Ten subjects (6 males and 4 females) performed a standard keyboard task for 30 min, using each of the two keyboards while wrist joint angles and electromyography (EMG) were recorded. Wrist extension and ulnar deviation angles were both significantly reduced with the split/angled keyboard (p = .030 and .010), and lower EMG activities were recorded in the extensor carpi radialis and ulnaris muscles. The present results implied that the split/angled keyboard may be a better instrument for prolonged keyboard operation, resulting in reduced strain in the wrist and forearm region.

The pattern of electronic game use and related bodily discomfort in Hong Kong primary school children

The present study examined the usage pattern of electronic game devices among primary school children in Hong Kong. Commonly used types of games devices were grouped into three main categories: large-screen/TV-based games, small handheld game devices and active game devices. A survey was conducted among 476 students in a local primary school, with 258 males and 205 females in the age range of 8-13. A self-reported questionnaire was administered at the school and students reported on the frequency and duration of play with eight types of common electronic game devices in the past month and any bodily discomforts associated with this activity. The results showed that use of several game devices (as many as 3-5 types) were common, with about 40% of the respondents being weekly users and 18% daily users. The design of the different electronic game controllers may affect the postures and muscle loading in the body in different ways, and prolonged exposure can lead to musculoskeletal symptoms. Nearly one third of the respondents (28.9%) reported some bodily discomfort associated with electronic game use. Neck discomfort was most commonly reported, followed by shoulders and fingers. Use of more than 2 h daily of small-screen handheld game devices significantly increased the risk of developing bodily discomfort in any region with an odds ratio of 4.75. The present results have highlighted the importance of monitoring primary school childrens exposure to electronic games, especially with small handheld devices, as this may have adverse effect on their musculoskeletal health.

Prevalence and risk factors associated with musculoskeletal complaints among users of mobile handheld devices: A systematic review

This systematic review aimed at evaluating the prevalence and risk factors for musculoskeletal complaints associated with mobile handheld device use. Pubmed, Medline, Web of Science, CINAHL and Embase were searched. The methodological quality of included studies was assessed. Strength of evidence for risk factors was determined based on study designs, methodological quality and consistency of results. Five high-quality, eight acceptable-quality and two low-quality peer-reviewed articles were included. This review demonstrates that the prevalence of musculoskeletal complaints among mobile device users ranges from 1.0% to 67.8% and neck complaints have the highest prevalence rates ranging from 17.3% to 67.8%. This study also finds some evidence for neck flexion, frequency of phone calls, texting and gaming in relation to musculoskeletal complaints among mobile device users. Inconclusive evidence is shown for other risk factors such as duration of use and human-device interaction techniques due to inconsistent results or a limited number of studies.