PREVALENCE OF CUMULATIVE TRAUMA DISORDERS IN CELL PHONE USERS

Journal of Musculoskeletal Research, Vol. 13, No. 3 (2010) 137 145 World Scientific Publishing Company DOI: 10.1142/S0218957710002545 PREVALENCE OF CUMULATIVE TRAUMA DISORDERS IN CELL PHONE USERS Charu Eapen,, Bhaskaranand Kumar and Anil K. Bhat, Department of Physiotherapy KMC Mangalore, Manipal University, Karnataka, India Department of Orthopedics KMC Manipal, Manipal University, Karnataka, India charu_mak@hotmail.com anilkbhat@yahoo.com Accepted 29 December 2010 ABSTRACT Purpose: In recent years, ownership and usage of cell phones have become widespread, especially amongst young people. The increasing use of text messaging on mobile phones has focused concern on possible musculoskeletal disorders for the users. Hence the purpose of this study was to find the prevalence of cumulative trauma disorders (CTDs) of the upper limb in cell phone users. Methods: A questionnaire-based survey was undertaken to detect the prevalence of CTDs in 1500 college students. Results: The response rate of the survey was 91.9%. Overall prevalence of CTD in the upper limb was found to be 18.5%. Maximum symptoms were noted in thumb (52%). Pain (61.7%) and fatigue (44.3%) were the two most common symptoms reported by the respondents. Conclusions: Mild form of CTD is present in students using cell phones and mainly depends on the pattern of phone usage. Keywords: Cumulative trauma disorders; Upper limb; Cell phone users. INTRODUCTION Cellular telephone use has increased exponentially, with 3.3 billion service contracts active worldwide or about one for every two people on the planet. 1 India has become the second largest wireless network in the world, overtaking * The paper was presented at AHTA2008 National Conference and Annual General Meeting, 24 26 October 2008, Melbourne Cricket Ground, Melbourne, Australia. Correspondence to: Dr. Anil K. Bhat, Department of Orthopedics, KMC Manipal, Manipal University, Karnataka, India. 137

138 C. Eapen, B. Kumar & A. K. Bhat the USA and second only to China, with an addition of about 8 million subscribers every month. 2 The total number of cell phones in use in India as at November 2009 is 506.04 million. 3 Cell phone users are at risk of developing various repetitive strain injury (RSI)-type conditions. The combination of repetitive movements, poor posture, and over-use of mobile phone for texting or playing games, without taking rest breaks, can cause injury to the nerves, muscles, and tendons in the fingers, hands, wrists, arms, elbows, shoulders, and neck, which if ignored, may lead to long-term damage. 4,5 Text messaging using mobile phones needs careful attention. The increasing use of text messaging on mobile phones has focused concern on possible musculoskeletal disorders for the users. In most cases, the digits used for texting are the thumbs of each hand, but these digits are not as well designed for fine manipulative or dexterous work as the other fingers. Apart from soft tissues, joints can also be damaged in the form of arthritis/ subluxation with excessive use of mobile phone for texting. 6 These problems have been recognized by several physiotherapy associations and by mobile phone operators worldwide. 7 9 There is still no literature on the prevalence of cumulative trauma disorders (CTDs) in mobile phone users among the student population who use their mobile phones extensively for communication in the form of text messaging and recreation in the form of playing games. Hence a study on CTD in cell phone users among students was undertaken. METHODS Questionnaires were given to 1500 students who use mobile phones. A purposely designed questionnaire was devised by the principal author to address the aims of the study. Its development involved discussions with colleagues, students, and also a pilot study. The questionnaire included both open-ended and closed questions and consisted of an introduction giving a brief overview of the proposed study and general questions covering demographic information, cell phone usage, and the duration of use. Questions were devised to know why students used the phone frequently, for example, messaging, playing games, or surfing the internet. The students were asked to report if they experience any symptom in the upper limb that could be attributed to the excessive use of the cell phone. A diagram of the upper extremity was also included on which the student had to mark the area of discomfort if the answer to the previous question was in the affirmative. They also had to select the types of symptoms suffered. Questions were also asked to know the personal belief of the cause of the symptom and its effect on their activities such as writing or lifting heavy objects. Both male and female students in the age group of 18 29 years who have been using a cell phone and were willing to participate in the survey were included in the study. All the students who had sustained recent injury (less than six months ago) to the hand or upper limb or are suffering from any inflammatory, degenerative, or neuromuscular condition of the hand or the upper limb affecting the usage of the limb for activities of daily living were excluded from the study. The study was approved by the Institutional Research Committee and the Institutional Ethical Committee. Statistical analysis was done using Statistical package SPSS version 11.5. Descriptive data of each variable were summarized as percentages of the respondents, with their age and duration of phone usage reported as mean SD. The proportional data of the CTDs group and the nonsymptomatic group (NSG) was analyzed using the Z test. Differences between the duration of phone usage between the CTD group and NSG

Cell Phones and Cumulative Trauma Disorders 139 were calculated using two-tailed independent t-tests. For all the tests, p < 0:05 was considered significant. RESULTS Questionnaires were given to 1500 students using cell phones. The flow of participants that resulted in 1363 completed questionnaires being used in data analyses is shown in Fig. 1. Of the 1363 respondents, the maximum number (n ¼ 1023, 75.1%) of respondents was present in the age group of 21 25 years. The age-wise distribution is shown in Fig. 2. The number of male and female respondents were 689 (50.5%) and 674 (49.5%), respectively. Pattern of Usage The overall pattern of usage of the cell phone by the respondents showed that the percentage of respondents using the phone for making calls and sending messages was almost equal (Table 1). Fig. 2 Agewise distributions of the respondents of the survey. Table 1 Pattern of Usage of Phone by the Respondents of the Survey. Usage Frequency Percent Making calls 952 69.8 Sending messages 944 69.3 Playing games 806 59.1 Others 235 17.2 Total 1363 100 Prevalence of CTDs Of the valid respondents, 253 subjects were having clinical symptoms, of which 126 and 127 were male and female respondents, respectively. Thus the prevalence rate of CTDs was found to be 18.5%. Right-hand dominance was found in 243 and left handedness in 10 respondents. This group will henceforth be referred as CTD group. The minimum duration of the mobile phone use was one month and maximum was 72 months (mean 30 15:3). When the duration of the cell phone usage of the CTD group (n ¼ 253) was compared with that of the remaining NSG (n ¼ 1110), the difference was not significant (t ¼ 0:93; p ¼ 0:35). Fig. 1 Flow of participants through the study. Cause Excessive use as the cause for their symptoms was reported by 184 respondents (72.7%). The

140 C. Eapen, B. Kumar & A. K. Bhat other causes stated were small hand set in 22 respondents (8.7%) or a heavy hand set in another 22 respondents (8.7%). Reasons other than the above-mentioned, such as small keys, and hard keys, were reported by 37 respondents (14.6%). There were some subjects who mentioned more than one cause. Pattern of Usage A high percentage of respondents who complained of symptoms used the cell phones for texting (n ¼ 244, 96.5%) (Table 2). When compared with the NSG, the results were very highly significant (p < 0:001) in terms of number of Table 2 Pattern of Usage of Phone by the CTD Group. Usage Frequency Percent Making calls 244 96.5 Sending messages 244 96.5 Playing games 165 65.2 Others 46 18.2 Total 253 100 messages sent by the CTD group. (NSG n ¼ 708=1110, CTD n ¼ 244=253). There was also a highly significant difference (p < 0:001) in the number of calls made (NSG n ¼ 700=1110, CTD n ¼ 244=253) and a significant difference (p ¼ 0:029) in the amount spent on playing games (NSG, n ¼ 641=1110; CTD, n ¼ 165=253). Other uses included miscellaneous activities, such as taking photographs, maintaining day s notes, listening to music, and setting alarm, which was not significant (p ¼ 0:66) among the two groups (NSG: n ¼ 189=1110, CTD: n ¼ 46=253). The difference between the two groups in the pattern of usage of phone is shown in Fig. 3. Symptoms The subjects complained of various symptoms during cell phone usage (Fig. 4). Maximum number of subjects (n ¼ 156, 61.7%) complained of pain, followed by fatigue (n ¼ 112, 44.3%), stiffness (n ¼ 42, 16.6%), and weakness (n ¼ 40, 15.8%). Though 13 subjects answered positive for the discomfort in the upper limb, they did not describe the nature of the symptom. Fig. 3 Pattern of usage of phone by the NSG and the CTD group.

Cell Phones and Cumulative Trauma Disorders 141 Distribution of Symptoms The respondents complained of the abovementioned symptoms in the whole upper limb. Majority of the respondents (n ¼ 133, 53%) complained of symptoms in the thumb (prevalence of radial ray CTD), followed by elbow (n ¼ 37, 15%) and wrist (n ¼ 33, 13%). The area-wise distribution of the symptoms is shown in the Fig. 5. A considerable number of respondents (n ¼ 39, 15.4%) did not indicate the area of symptom. Fig. 4 Symptoms reported by the CTD group. Duration of Symptoms For most of the subjects (n ¼ 138, 54.5%) the symptoms lasted less than 5 minutes and it did not affect their activities such as writing or lifting objects. A majority of the subjects (n ¼ 144, 56.9%) felt the need to shift the phone to the other hand because of the symptoms. Only 23.3% (n ¼ 59) said that the discomfort affected their activities of writing or holding fine/small objects. DISCUSSION Prevalence of Mobile Phone Usage Questionnaires were distributed to 1500 students of the Kasturba Medical College, Mangalore, to identify students having CTDs because of excessive use of mobile phones. The response rate (91.9%) was very high, indicating good representation and response from the students. Amongst the study population, the prevalence of current mobile phone ownership was extremely high, being 100%. Data on the prevalence of mobile phone usage have also been collected in previous studies. 10 18 Fig. 5 Areawise distributions of symptoms in the upper limb in the CTD group.

142 C. Eapen, B. Kumar & A. K. Bhat Pattern of Usage In our study, the average duration of usage of the mobile phone was 29 months (1 120 months). Majority of the respondents used the mobile phone primarily for making calls, but almost an equal number of respondents used it for text messaging. The mobile phone was also used for other miscellaneous purposes, such as playing games, setting alarm, clicking photographs, listening to music. Data collected from the studies on prevalence of mobile phone usage also show that the usage patterns vary widely depending on the age, country of residence, and the study population concerned. 17 Mobile phone text messaging is often more affordable than voice messaging in the developing world and is increasingly becoming popular among teenagers and young adults. 11,19 Prevalence of CTDs in Cell Phone Users This is the first study to identify the prevalence of CTD in cell phone users. Although there have been isolated cases reported of texting tendinitis, Play Station thumb, and Wittis all itises of the microchip age, 20 25 no study has reported the prevalence of CTD of the upper limb in cell phone users. This study found that 18.5% (n ¼ 253=1363) of respondents complained of symptoms in the upper limb due to the overuse of cell phone, with more than 50% (n ¼ 133) of them complaining of symptoms in the thumb aggravated by excessive use due to messaging. More than 70% (n ¼ 184=253) of the respondents complained that the symptoms they suffered were because of excessive use of the mobile phone, and this can be seen in the pattern of usage of the mobile phone by this group. The pattern of usage showed that a very high percentage (96.5%, n ¼ 244=253) of respondents used the mobile phone for sending text messages. The difference was highly significant (p < 0:001) in terms of the number of messages sent by the group that did not complain of any symptom (63.1%, n ¼ 700=1110) to the group with CTD (96.5%, n ¼ 244=253) that complained of symptoms in the upper limb. Hence, it may be presumed that repetitive activity, as in sending messages, may be the cause of CTD. The average duration of mobile phone usage was 29.7 months, with the maximum number of respondents reporting the usage between 24 36 months. This did not vary much with that of the NSG (29 months). In our study, the duration of usage of the mobile phone did not have any influence in the production of symptoms. It depended more on the pattern of usage on a particular day. In a study done by Chris Jensen on computer operators, total experience with computer use did not have any effect in causing neck or hand symptoms. However, work tasks requiring mouse use for at least one-half of the work time in a day were found to be associated with an increased risk of hand-wrist symptoms. 26 Our results on symptoms in cell phone users are consistent with these results on computer operators. In our study, the duration of usage of phone (time since the person owned a phone) did not have any effect on the symptoms. It depended more on the usage on a particular day and on the pattern of usage (e.g. texting). We also ruled out that none of the students were involved in regular recreational activities such as racket games involving repetitive movements of the hand or wrist or were regular users of computers (daily usage >3 hours). Hence, these symptoms can be attributed to cell phone use alone. In our study, the complaint of symptoms in the distal part of the upper extremity f(thumb (radial ray)): 53% (n ¼ 133), elbow: 15% (n ¼ 37), wrist: 13% (n ¼ 33), fingers: 12% (n ¼ 30), hand: 10% (n ¼ 26), forearm: 7% (n ¼ 18)g was more when compared with the proximal part f(shoulder: 7%

Cell Phones and Cumulative Trauma Disorders 143 (n ¼ 17) and arm: 6% (n ¼ 14)g. This could be because they used the phone for messaging and hence more stress on the hand, fingers, and thumb. Text messaging is becoming increasingly popular among students because it is much cheaper, affordable, and keeps them connected with their peers. 27 The fact that more than half of those who complained of symptoms reported its presence in the thumb suggests that the stress is concentrated on the thumb when they use their hands to hold the small phone and operate it with the thumb while the index finger supports the phone. (Fig. 6). Regular use of text messaging over a long time could cause repetitive strain, which may lead to both short- and long-term injuries. In our study, the possible cause could be repetitive movements of the thumb without adequate rest, 28 which was also self-reported by the respondents as possible cause of symptoms. Only one study done by Chany et al. 29 has studied the effect of a clamshell phone usage on muscle fatigue as compared to the use of a normal office phone. They found that fatigue occurred in the thenar muscles of the hand due to the precision-power grip required to hold the small Fig. 6 Index finger supporting the phone while text messaging. clamshell phone as compared to the power grip to hold the normal office phone. Deltoid fatigue was also noted, which they attributed to increased moment and mass in participants with long limbs while holding the phones in internal rotation. However, we did not study the relationship between the phone design and the symptoms. In our study the proximal symptoms could be because of the position of holding the phone during talking. Oftedal et al. 30 have noted muscle strain in the neck because of holding the phone. Sandstorm et al. 31 also reported neck pain in some of their respondents due to muscle strain but they attributed it to calling time and number of calls. Cell phone elbow has been reported leading to symptoms of cubital tunnel syndrome possibly because of stress on the ulnar nerve in the flexed position of the elbow. 1 Several symptoms are associated with CTD. Most of them are manifested by pain, discomfort, or tingling in the upper extremity. 32 Pain is the most prominent symptom. 33 In our study, the maximum number of respondents reported pain (61.7%, n ¼ 156=253) and fatigue (44.3%, n ¼ 112=253). Other symptoms such as stiffness, weakness, tightness, and cramping, were also reported. Redness, swelling, loss of control, and pins and needles sensation were noted by a small percentage of the respondents. The subjects who complained of pain reported most commonly of mild to moderate intensity. Of the respondents who had pain, almost 55% (n ¼ 138=253) reported the symptoms lasting for less than five minutes after excessive use of mobile after which they stopped the activity and took rest. These symptoms are characteristic of CTD. Symptoms tend to be mild initially and diminish with modification of activities and return when activities are resumed. 34 36 Our respondents with pain changed their hands to continue the activity or stopped messaging. The continuous exposure to rapid, repetitive, and forceful movements may lead to

144 C. Eapen, B. Kumar & A. K. Bhat localized muscle fatigue with ischemia and metabolic changes that impair muscle enzyme function. The affected muscles and their tendons are then more susceptible to micro-tears and inflammatory changes, resulting in pain that persists during the work tasks (texting) and at rest, jeopardizing the individual s ability to work and perform daily tasks. In the severe state, the symptoms persist even during rest, sleep is disturbed, and the pain is aggravated by even nonrepetitive movements. 35,37 In our study, activities of daily living were affected in less than a quarter (23.3%) of those who complained of symptoms. This presentation shows that the effect of CTD was minimal and probably in the initial phase. However, it should be noted that though the presentation appears to be mild, this population is young, and if the soft tissues and the joints are subjected to repeated stress, it may lead to early degenerative changes. It is interesting to note that more than half of the population affected by the mild form of CTD complained of symptom in the thumb. According to Clifford, the thumb is not a very dexterous digit. It is good at grasping but not good for repetitive movement. 38 The thumb is responsible for 40% of the function of the hand. It is particularly relevant for the performance of the precision, pulp to pulp, tripod, and key grips. Pain, deformity, or malfunction of a thumb will therefore have significant consequences on overall hand function. 39 This group needs to be studied in-depth in future. CONCLUSION The prevalence of CTDs of the upper limb in cell phone users was 18.5%. It was found that the duration of cell phone usage did not have any influence in the production of the symptoms of CTD. It depended more on the pattern of cell phone usage during the day. Clinically, the CTD was of mild type because the symptoms were produced during activity, lasted for a few minutes, and were relieved once the activity was stopped. The most common symptoms present were pain and fatigue, which were of mild to moderate intensity. Symptoms were reported more in the distal part of the upper extremity than the proximal part. Symptoms in the thumb were present in 53% of the respondents who had CTD. References 1. Darowish M, Lawton JN, Evans PT. What is cell phone elbow, and what should we tell our patients? Cleve Clin J Med 76: 306 308, 2009. 2. Information Note to the Press [Press Release No. 79/ 2009]. Telecom Regulatory Authority of India (2009). Available at: http://www.trai.gov.in. Accessed Jan 2010. 3. Infoplease. Cell phone usage worldwide, by country. (2009) Available at: http://www.infoplease.com/ipa/ A0933605.html. Accessed Jan 2010. 4. Guide for young people: How to avoid RSI. Available at: http://rsiaction.org.uk/rsi-conditions-and-prevention. Accessed Jan 2010. 5. Weinstein SM, Robinson JP, Rondinelli RD, Scheer SJ. Case studies in upper extremity cumulative trauma disorders. Arch Phys Med Rehabil 78(3): S16 S20, 1997. 6. Ming Z, Pietikainen S, Hänninen O. Excessive texting in pathophysiology of first carpometacarpal joint arthritis. Pathophysiology 13(4): 269 270, 2006. 7. Thumb pain and the danger of text message injury from Virgin Mobile- in solution for pain-thumb Pain (2009). Available at: http://www.ergonomictimes.com. Accessed Jan 2010. 8. Text messaging injuries (TMI) on the rise. (2005) Available at: www.textually.org/textually/archives/ 2005/05/008352. Accessed Jan 2010. 9. Millions suffer from text messaging Xrcises 2 prolng yr txtin life. (2006). Available at: http://www.theregister. co.uk/2006/02/22/text injury/. Accessed Jan 2010. 10. Schüz J. Mobile phone use and exposures in children. Bioelectromagnetics Suppl 7: S45 S50, 2005. 11. Kuntsche E, Simmons-Morton B, ter Bogt T, Queija IS, Tinoco VM, de Matos MG et al. Electronic media communication with friends from 2002 to 2006 and links to face-to-face contacts in adolescence: an HBSC study in 31 European and North American countries and regions. Int J Public Health 549(Suppl 2): 243 250, 2009. 12. S oderqvist F, Carlberg M, Hardell L. Use of wireless telephones and self-reported health symptoms: A population-based study among Swedish adolescents aged 15 19 years. Environ Health 7: 18, 2008.

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