Author: Sun, Tianbao
Title: A study of spine and upper limb kinematics in using smartphone among young adults with and without neck-shoulder pain
Advisors: Tsang, Sharon (RS)
Szeto, Grace (RS)
Degree: DHSc
Year: 2021
Subject: Smartphones -- Health aspects
Shoulder pain
Neck pain
Hong Kong Polytechnic University -- Dissertations
Department: Faculty of Health and Social Sciences
Pages: xiii, 127 pages : color illustrations
Language: English
Abstract: Objective: The priority of this research is to achieve the following three objectives. Firstly, the study examined the spine and upper limbs kinematics when young individuals with and without neck-shoulder pain used their touch-screen smartphones in different body postures. Secondly, it investigated the changes in cervical re-positioning accuracy and intensity of neck-shoulder pain when the asymptomatic and symptomatic groups used smartphones in different postures over a period of 20 minutes. Finally, the study investigated the association of neck-shoulder pain with different variables including demographic characteristics, kinematic changes of posture angles, and cervical re-positioning accuracy. Recommendations are made on the optimal strategies to prevent neck-shoulder pain when using smartphone for an extended period of time, in the scope of posture related factors.
Methods: This study involved two groups of participants recruited through convenience sampling and advertising among interns, and young colleagues from the local hospitals and colleges. There were a total of twenty-one participants with neck-shoulder pain in the asymptomatic group. Twenty-four gender-matched participants who reported to be healthy and free of existing neck-shoulder pain were recruited in the asymptomatic group. Participants in both groups were right-handed. Each of the participants signed an informed consent form and completed the Neck Disability Index (NDI) and Tampa Scale for Kinesiophobia (TSK) questionnaires. The spine and upper limb kinematics ( including postural joint angles and cervical re-positioning accuracies)were investigated in 3 positions for both groups while using a touch-screen smartphone for 20 minutes each. The 3 positions are:
• Position 1 (upright): Supporting the smartphone in mid-air without arm supported.
• Position 2 (slouched): Resting the smartphone on the lap with wrists resting on thighs.
• Position 3 (forward leaning): Using the smartphone while the trunk is leaning forward with elbows on thighs.
A video was set up to capture the sagittal profile of the participants' posture for the entire 20 minutes in each position and photographs from regular intervals (5 sec, 10 min and 20 min) were extracted from the postural joint angles using the Kinovea 8.15 software. In addition, the Numeric Pain Rating Scale (NPRS) was used to record the pain score and the cervical re-positioning test was used before and after the 20 minutes duration of each position. The software IBM SPSS statistics 22.0 indicated that all the considered factors were at a significant level of p< 0.05. A mixed repeated measurement models RMANOVA, t-test, and logistic regression were performed to investigate the relationship between body positions and time factors, and compared between groups. Particularly, the relationship between demographic factors, postural joint angles, cervical re-positioning accuracies, and neck-shoulder pain were examined.
Results: A total of 45 smartphone users with 26 males and 19 females participated in the study. The symptomatic group (n= 21, 7 males, 14 females; mean age = 21.71± 0.85 years), had a mean score of NDI of 5.67 ± 3.02 (min-max: 1-13/50) and pain intensity (NPRS) of 4.81 ± 1.60 (min-max: 3-8/10) over the last 30 days respectively. Apart from self-reported duration of smartphone used per day (p= 0.005), there was no significant difference in the demographic factors between the symptomatic group and the asymptomatic group (n=24) (p >0.05).
Generally, each subject was in a flexed neck posture with flexed elbows when gaming on the smartphone. Considering 20 minutes of gaming by both groups, there were no significant differences in A-HNFA (adjusted head neck flexion angle), UTFA (upper trunk flexion angle), LTFA (lower trunk flexion angle), EFA (elbow flexion angle) and Spine A (total spine angle, sum of A-HNFA, UTFA and LTFA) for all 3 positions, which exhibited similar trend lines. However, significant differences were seen in the extent of postural variations (difference between maximum and minimum postural flexion angle) in Spine A (p= 0.006) during twenty-minute duration at position 1 (upright) and LTFA (p= 0.026) at position 2 (slouched).
There were no significant main effects of position differences in cervical re-positioning accuracy across all 3 positions (p> 0.05). However, there were significant main effect differences in left side flexion accuracy (LSF-accuracy, p= 0.010) between the two groups. The asymptomatic group showed increased cervical re-positioning accuracy in position 1 (upright) with error distance (cm) decreased for E-accuracy (extension accuracy), F-accuracy (flexion accuracy), RSF-accuracy(right side flexion accuracy), LSF-accuracy (left side flexion accuracy) and RROT-accuracy (right rotation accuracy); position 2 (slouched) for E-accuracy, F-accuracy, RSF-accuracy, LSF-accuracy and position 3 (forward leaning) for E-accuracy, RSF-accuracy, RROT-accuracy and LROT-accuracy (left rotation accuracy) following 20 minutes of gaming on the smartphone. However, the results of the symptomatic group were different. The accuracy of their cervical re-positioning worsened with error distance (cm) increased for E-accuracy, F-accuracy and LROT-accuracy at position 1 (upright), E-accuracy, F-accuracy, RSF-accuracy and LROT-accuracy at position 2 (slouched), and E-accuracy and RROT-accuracy at position 3 (forward leaning).
With regard to the NPRS of neck-shoulder pain score, significant differences in main effects of position (p= 0.002) and time factor before and after the 20 minutes of smartphone gaming (p< 0.01) were found. The interaction effects were considered between group and position (p= 0.044), between group and time (p= 0.040), and between position and time (p= 0.017). These considerations did not exhibit any significant difference for NPRS changes in the 3 positions between the two groups (p> 0.05). Univariate analysis was performed first with each independent variable including demographic characteristics, postural joint angles and cervical re-positioning accuracies respectively. Only those variables that reached p<0.05 were entered into the binary logistic regression model to explore the association of the presence or absence of neck-shoulder pain. We found that age (p= 0.038, 95% CI 1.115-49.507), self-reported duration of smartphone use per day (p= 0.024, 95% CI 1.695-1501.646), E-accuracy changes (p= 0.034, 95% CI 1.048-3.230) and extent of postural variations in Spine A (p= 0.024, 95% CI 0.604-0.965) were significantly associated with neck-shoulder pain at position 1 (upright).
Conclusion: This study demonstrated that young adults with mild neck-shoulder pain exhibited altered posture kinematics when compared with healthy participants before and after gaming on a smartphone for an extended period of time. Participants with mild neck-shoulder pain tended to show cervical re-positioning accuracy worsen and different extent of postural variations. This was associated with a significant increase in pain score after the gaming immediately compared with before the gaming. The outcomes of this investigation highlight the importance of ergonomics education to avoid neck-shoulder pain occurrence or aggravation during prolonged use of a smartphone. Further study should continue to explore different postures to use a smartphone and different smartphone tasks to develop ergonomic guidelines of smartphone use.
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