KINANTHROPOMETRY Analysis of Correlation between Anthropometry of Hand and Smartphone Overuse on Musculoskeletal Pain in Thumb/Wrist in Medical Students: A Cross Sectional Study at Tertiary Care Center of Central India

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Introduction
In this era of evolving technologies, smartphone devices upgraded in both design and functions. Smartphones have replaced mobile phones and become the new form of communication around the globe. Smartphones combine normal mobile phone features with other personal digital assistance functions, including internet browsing for learning, accessing email, global positioning system (GPS) navigation, desktop synchronization, capturing high-quality photos, and large displays even replacing computers (Choi et al.,2011). Today, it is estimated that more than 5 billion people have mobile devices, and over half of these communication devices are smartphones and became an integral part of their lifestyle. (Choi et al., 2011: Shim, 2012. A recent study showed that 79% of the population between the age 18-44 years have their smartphones with them almost all the time, with only two hours of their waking day spent without their smartphone in hand ( Kim & Kim, 2015;Neupane et al.,2017). According to press release number 16/2021 of the Telecom Regulatory Authority of India published on March 17, 2021, there are a total of 1,163.41 million wireless subscribers in India (until January 2021), with a monthly growth rate of 0.84% (Jonsson et al., 2011). The habit of continuous checking and utilization of smartphone applications for long durations causes musculoskeletal pain due to operational stress over the thumbs, fingers, and wrist, along with stress, sleep disturbances, decreased physical activity, and poorer educational performance (Shim,2012;Kim & Kim, 2015;Neupane et al.,2017). The disorders are because smartphone use typically requires thumb and finger interactions with the small mobile screen (Neupane et al.,2017). There are very few studies reporting the relationship of continuous smartphone use in awkward wrist posture leading to collective trauma disorders of the wrist joint and hand particularly when the wrist, hands, and fingers are overused (Neupane et al.,2017;Jonsson et al., 2011).
The Smartphone Addiction Scale Short Version (SAS-SV) is an important tool to categorize smartphone addiction scientifically (Kwon et al.,2023). The repetitive static motion of the hands may also decrease blood supply and prevent nutrients from being delivered to muscles, thus leading to pain and muscle fatigue (Neupane et al.,2017;Jonsson et al., 2011). Chamy et al.,(2007) concluded that participants with short limb lengths developed more severe signs of thenar fatigue whereas participants with longer arms developed greater discomfort in the neck, shoulder, and back. They strongly recommended that the anthropometry of hand and phone design affected the development of discomfort and fatigue during phone use (Chamy et al., 2007). Nordic Musculoskeletal Questionnaire was clinically used to assess musculoskeletal pain due to the overuse of Smartphones (Young,1998;Kahraman et al.,2016 ).
Considering these applied aspects, the present study was conducted with the aim to evaluate the relationship between anthropometric measurements of the hand and intensity of musculoskeletal pain in the thumb or wrist due to overuse or addiction to smartphones in adults.

Material and Methods
The proposed observational, questionnaire-based non-invasive study was conducted in AIIMS Bhopal on adult subjects who have consented to the study. The permission from Institutional Ethics Committee was obtained before starting with the project. The study was conducted on 200 (130 male and 70 female) adult participants who volunteered for the study. The participants were explained about the details of the study. Participants were properly informed to record study parameters, and written consent was taken from the participants. Individuals above 21 years of age using smartphones for more than 3 years and who volunteered to adhere to the study protocol and gave consent for participation were included in the study. Confidentiality was maintained in all aspects. Pediatric age groups and individuals who refused to volunteer were excluded from the research project. The observations of participants were recorded under the following aspects:

Personal and Demographics
Personal details such as name, age, sex, weight, and height were recorded. Body mass index (BMI) was calculated. The model of the smartphone, its usage time, duration of owning a smartphone, and the purposes of smartphone use in a typical day, including (i) talking (voice-to-voice), (ii) text messaging, (iii) listening to music, (iv) DOI: 10.34256/ijk2316 watching videos, (v) social networking, (vi) gaming, and (vii) other uses was noted as in Fig 1 and Fig 2. The percentage of the population using various sizes of mobile was shown in Table 1.

Anthropometric parameters
The anthropometric details of the palm of participants were recorded using a digital sliding caliper to the nearest millimeter.
Hand Length was measured by measuring the linear distance between the midstylion and dectylion sites.
Palm breadth (metacarpal) was measured from the straight distance between the base of the second metacarpal bone to the base of the fifth metacarpal bone.
The length of the middle finger was measured from the metacarpophalangeal joint to the tip of the middle digit.
All measurements were taken while the participants sat on a chair and their hands were kept on a horizontal platform. Fingers were kept close to each other.

Phone Model Groups
The groups of the smartphone were categorized according to the size of the touch screen which was measured in inches from one corner of the screen diagonally across to the opposite corner. 16 touch screen phones were used, 6 models from iPhone Apple, 4 Oppo, and 6 models from Samsung Galaxy. The screen sizes were measured using a Vernier caliper diagonally across the screen. Then, based on the screen size, mobile phones were grouped into small, medium, and large phone sizes as shown in Table 1, Figure 3, and Figure 4.

Smartphone Addiction Scale (SAS)
To study the level of smartphone addiction, the SAS carrying a 33-item scale in which responses to items were taken on a six-point Likert-type scale from 1 (strongly disagree) to 6 (strongly agree) (Young,1998). It was based on the Internet Addiction Test (Namwongsa et al., 2018 ) and comprised six factors: daily-life disturbance, positive anticipation, withdrawal, cyberspace-oriented relationships, overuse, and tolerance. Higher scores indicate a higher risk of smartphone addiction. The total scores ranged from 33 to 198. A cut-off point for smartphone addiction was not reported in the original scale, with higher scores indicating a greater risk of being addicted to smartphones. A reliability and validity study of the Turkish version of the SAS was conducted by Demirci et al. (2014), and Cronbach's alpha was 0.94.

Modified Nordic Musculoskeletal Questionnaire (mNMQ)
In the present study, the mNMQ was used (Kahraman et al., 2016;Choi, 2018 ). The mNMQ consists of items relating to six body regions (neck, shoulders, upper back, lower back, elbow, and wrists-hands) from the original NMQ, and assesses upper body musculoskeletal symptoms related to any pain or numbness in the previous 12 months and last seven days. The mNMQ investigates pain and numbness in the body regions that are used most frequently during smartphone use, enabling participants to answer "yes" or "no" by using a simple body image. The participants were asked whether the pain that had developed within the past year prevented them from doing normal work (at home or outside the home) or whether hospitalization was required due to this pain. The Turkish version of NMQ was used in the present study (Choi, 2018).

Discussion
The present study observed addiction to smartphones among medical graduates which was 35.5% ( Table  1 & Table 4). Young-Soon Choi from Korea reported a degree of addiction to smartphones in 32.1 % of college students. Choi (2018) also observed that participants who experienced physical pain because of smartphone use were 39.1%. Wrist, finger pain, and neck pain were in the order of joints (Choi,2018). The findings were still higher in Turkish university students as 43%. (Kim & Kim, 2015). This overuse of smartphones was affecting the health as well as academic performances of students.
The most frequent musculoskeletal pain due to smartphone usage was in the neck region which was 38.5%, followed by wrist/hand pain observed in 29.0% of participants ( Table 5, Table 6 & Table 7). In a study from Egypt, the most frequent pain experienced by the physical therapy students was in the neck, eyes, and back region (AlAbdulwahab et al., 2017) while in Turkey, the incidence of musculoskeletal pain was also identified in the neck, shoulder, and upper back (Kim & Kim, 2015). Yang and colleagues (Yang et al., 2016), reported neck and elbow areas as the most frequent body pain suffered by adolescent students whereas in Korea, the most common musculoskeletal pain endured by the students was in neck and shoulder. (Choi,2018;Karki et al.,2020;Shan et al., 2013). Musculoskeletal pain in the neck was found to be associated with the overuse of smartphones (r = 0.011, p ≤0.05), but the present study did not find any significant correlation between overuse of smartphones and wrist/hand pain ( Table 7 and Table 10, r = 0.107, p ≥0.05), which was similar to the study performed by AlAbdulwahab et al. (2017). The hand and neck might move continuously toward the screen throughout the day if smartphones were used excessively. Such motions increase the likelihood of chronic neck pain.
The overuse of large size of smartphones was related to the degree of musculoskeletal pain (Table 8, Table  9, Table 11). The smartphone brands were grouped based on their diagonal screen size measurements. The results showed that 18 out of 200 participants used small-sized phones, 148 participants used medium-sized phones, and 34 used large-sized phones. So, the majority of participants tend to use small to medium size mobile phones. This can be related to the less reported hand pain as well as the awareness of the subjects to pick the mobile size that matches their hand size (Table 12, Table 13, Table 14).
Pain in the neck was the most common symptom observed in the participants and was due to regular posture adopted by smartphone users (Alhazmi et al., 2018;Elsertyet al.,2018;Kamel et al.,2020;Tonga et al.,2017;Walankar et al.,2021). They remain in this posture while looking at their devices for long time. The length of time devoted to smartphone usage and adopting flexed neck postures resulted in pain and discomfort in the neck region in the long term (Namwongsa et al.,2018). Furthermore, smaller smartphone screen sizes might indirectly influence the adoption of different neck positions to enhance looking at the screen. Smaller screens might cause more forward bending of the neck, reducing the distance between the screen and the user's eyes (Ning, et al.,2015). A compensatory forward neck bending might be occasioned by increased neck muscle activity, which might have affected DNF endurance in the smartphone-addicted groups. Previous studies supported that the mechanical steadiness in the cervical region was the main function of the deep muscles of the neck namely the longus capitis, longus colli which provided longitudinal spine stability in the cervical region (Domenech et al., 2012 ;Ning et al., 2015). Alshahrani and colleagues (2021) in their extensive study on neck and hand muscle endurance in smartphone users reported that excessive use of a smartphone and the posture of keeping the cervical spine flexed for long durations were associated with high addiction, which led to long-term health issues. They emphasized the fact that students should be made aware of the long-term ill effects of smartphone addiction (Alshahrani et al.,2021). Hence, during the present study, all the participants were advised regarding precautions during the use of smartphones for longer durations for academic purposes. Taking a rest for a few minutes in between the sessions and exercises to increase the endurance of muscles of the neck and wrist/ hand would surely help in reducing the symptoms of smartphone over usage.

Conclusion
A strong direct correlation was noted between smartphone overuse and neck pain of the participants but no relationship was observed between the use of smartphone and wrist pain. This could be because of the very short duration of the study and limited number of participants. The findings showed a positive association between smartphone overuse and neck pain and no correlation was established between smartphone overuse with wrist pain or hand anthropometry.