Keywords
mobile phones - wrist trauma - hand trauma - cumulative trauma disorders
Introduction
The 19th century witnessed the advent of new information and communication technologies;
by the late 1870s, the first telephones caused a revolution in culture and communication.
However, the real revolution occurred in the 21st century with social/digital networks
and mobile technologies. A clear example is the smartphone, which currently surpasses
notebook computers as a tool for internet access, communication, and work; it also
aggregates functions from several other devices.[1]
[2]
According to the Brazilian National Telecommunications Agency (Agência Nacional de
Telecomunicações, ANATEL, in the Portuguese acronym),[3] Brazil had approximately 236 million cell phones in March 2018; this is a high figure
compared to the number of inhabitants, of about 209.1 million per the Brazilian Institute
of Geography and Statistics (Instituto Brasileiro de Geografia e Estatística, IBGE,
in the Portuguese acronym).[4] Cell phones are a valuable invention with several features that make daily life
easier. However, while it provides benefits, it can also lead to physical harm, as
shown by Guterres et al.,[5] who evaluated musculoskeletal complaints in every region of the body among smartphone
users and found the neck (49.4%) as the area most frequently involved, followed by
the wrists and hands (37.9%).
Anatomically, the wrist is considered one of the most complex joints in the body.
It performs flexion, extension, ulnar deviation, radial deviation, and circumduction
movements. The hand is the distal end of the upper limb, and it is considered the
most important functional part of the upper appendicular skeleton. The carpometacarpal
joints consist of the second row of the carpal bones and metacarpal bones. The metacarpophalangeal
joints, formed by the metacarpal bones and the proximal phalanges, perform flexion,
extension, hyperextension, adduction, and abduction movements. Lastly, the interphalangeal
joints are located between the phalanges and enable flexion and extension movements.[6]
[7]
The thumb is the first digit, and it presents the highest level of functionality.
Its carpometacarpal joint consists of the trapezium and the base of the first metacarpal
bone, and it enables flexion, extension, adduction, abduction, opposition, reposition,
and circumduction of the thumb. Although the thumbs are highly mobile, their design
does not enable the heavy lifting required to handle a smartphone; as such, the level
of effort may vary depending on the mode and speed of typing.[8]
The highest prevalence of upper-limb symptoms resulting from repetitive efforts occurs
in the hands. These symptoms are due to repetitive movement, vibration, use of hand
tools, high forces, and inadequate postures, which cause discomfort, feeling of heaviness,
pain, numbness, tingling, and decreased functionality and strength.[9] Among these disorders, De Quervain tenosynovitis and carpal tunnel syndrome prevail.[10]
Although the association between repetitive movements and musculoskeletal morbidities
is a fact, few studies in the literature report these conditions with the use of smartphones.
It is possible to prevent or delay these physical health issues by using smartphones
in moderation and correctly; the population and healthcare professionals must know
these risks to formulate preventive strategies and measures. Thus, the present study
aims to investigate the long-term use of smartphones as a risk factor for the development
of wrist and fingers conditions.
Materials and Methods
The present is a descriptive, exploratory study with a quantitative approach to assess
the prevalence of injuries among smartphone users. The research was conducted at a
college, and the sample consisted of one hundred students. The Research Ethics Committee
approved the study under opinion number 2,889,152 before data collection.
The subjects included were enrolled at the college during the research period, had
been using smartphones for more than 5 years, and were 21 to 30 years old. The excluded
subjects were those performing any paid activity other than their college studies,
or those who had a previous diagnosis of rheumatic diseases.
After presenting the study to the participants, they signed an informed consent form
before data collection, which occurred in three stages. The first stage was the application
of a semi-structured questionnaire ([Appendix A, Supplementary Material], available on-line only)[11] consisting of closed questions with a single alternative to be checked, except when
otherwise stated. This questionnaire enabled the collection of data pertaining to
the sociodemographic profile and routine cell phone use of the participants. The presence
of pain on evaluation was verified using the visual analog scale (VAS).
The second stage consisted of the application of the Boston Carpal Tunnel Questionnaire
(BCTQ) to quantify six critical domains: pain, paresthesia, numbness, weakness, nocturnal
symptoms, and global functional status. This questionnaire has two scales, one for
the severity of symptoms (S scale) and one for functional status (F scale). The S
scale contains 11 multiple-choice questions with scores from 1 to 5, in which 1 represents
the absence of symptoms and 5, severe symptoms. The score is an average of these 11
individual items. The F scale addresses 8 usual activities, with scores from 1 to
5 points, in which 1 represents no difficulty, and 5 indicates that the subject cannot
perform the activity. Its total score is the average value of these eight items.
The sample data were descriptively analyzed and tabulated using the Statistical Package
for the Social Sciences (IBM SPSS Statistics for Windows, IBM Corp., Armonk, NY, United
States) software, version 22.0, to determine the means, minimum, maximum, standard
deviation (SD), and percentage distribution per the specificity of each variable.
The Chi-squared test evaluated the significance between the variables with a 95% confidence
interval (95%CI; p < 0.05). The results are shown in tables.
Results
[Table 1] shows the sociodemographic profile of the research participants. The average age
of the students was of 22.73 years (SD: ± 2.296). Regarding gender, there was a prevalence
of females (69%). In addition, right-handed subjects were predominant (89%).
Table 1
|
Variables
|
Categories
|
n
|
%
|
Average
|
Standard deviation
|
|
Age
|
|
−
|
−
|
22.73 years
|
± 2.296
|
|
Gender
|
Female
|
69
|
69
|
−
|
|
|
Male
|
31
|
31
|
|
−
|
|
Dominant hand
|
Right
|
89
|
89
|
−
|
|
|
Left
|
11
|
11
|
|
−
|
[Table 2] reveals that most students (57%) had been using smartphones for 5 to 10 years; 33%
reported taking breaks of up to 20 minutes during use, and only 22% reported not doing
so. As for daily time distribution, 28% used the smartphone for more than 10 hours,
and 84% reported typing as the main activity performed.
Table 2
|
Variables
|
Categories
|
n
|
%
|
|
Time of use
|
5–10 years
|
57
|
57
|
|
10–15 years
|
33
|
33
|
|
More than 15 years
|
10
|
10
|
|
Time of daily use
|
More than 10 hours
|
28
|
28
|
|
5–8 hours
|
28
|
28
|
|
8–10 hours
|
19
|
19
|
|
Other
|
25
|
25
|
|
Pauses during use
|
Up to 20 minutes
|
33
|
33
|
|
30 minutes to 1 hour
|
27
|
27
|
|
No pauses
|
22
|
22
|
|
Other
|
18
|
18
|
|
Main activity performed
|
Typing
|
84
|
84
|
|
Talking
|
8
|
8
|
|
Other
|
8
|
8
|
[Table 3] describes the most frequent way of handling and typing. A total of 51% of the subjects
held the device only with their right hand, and 71% typed using both hands.
Table 3
|
Variables
|
Categories
|
n
|
%
|
|
How the smartphone is held
|
With the right hand
|
51
|
51
|
|
With both hands
|
45
|
45
|
|
With the left hand
|
4
|
4
|
|
How one types
|
With both hands
|
71
|
71
|
|
With a single hand
|
29
|
29
|
[Table 4] shows a positive correlation between the time of use and discomfort (p = 0.000). Out of the 28 students reporting cell phone use for more than 10 hours
a day, 89.3% mentioned some episode of discomfort during use, as well as in all other
time variables. This confirms that the daily use of smartphones can cause wrist and
finger soreness, regardless of the number of years that the device has been used,
as even those who had been using them for shorter periods reported discomfort.
Table 4
|
Variables
|
Categories
|
n
|
%
|
|
Have you ever felt any discomfort during use?
|
Yes
|
85
|
85
|
|
No
|
15
|
15
|
|
Where?
|
Wrist
|
54
|
26.3
|
|
Thumb
|
49
|
23.9
|
|
Hand
|
28
|
13.7
|
|
Forearm
|
20
|
9.8
|
|
Other
|
54
|
26.3
|
|
Symptom
|
Numbness
|
43
|
30.7
|
|
Tingling
|
34
|
24.3
|
|
Pain
|
30
|
21.4
|
|
Other
|
33
|
23.6
|
|
Visual Analog Scale
|
With pain – 24% (n = 24)
|
Moderate
|
13
|
54.2
|
|
Mild
|
11
|
45.8
|
|
No pain
|
−
|
76
|
76
|
When asked if they had ever felt any discomfort in the upper limbs while using a smartphone,
85% of the subjects answered yes. The most affected regions were the wrist (26.3%)
and the thumb (23.9%). Regarding the characteristics of these symptoms, 30.7% reported
numbness, 24.3%, tingling, and 21.4%, pain. Only 24% of the sample reported pain on
the VAS assessment; among them, 54.2% described moderate symptoms.
Participants self-reported numbness and tingling as the most common discomfort, especially
in the wrist, thumb, and hand. These findings may indicate carpal tunnel syndrome
and De Quervain tenosynovitis, or a predisposition for their development.
[Table 5] shows the overall mean score on the S scale of the BCTQ and the mean values per
symptomatology. The overall mean score was of 1.61 (SD: ± 0.485), indicating mild
symptoms, since 1 and 2 respectively refer to no and few symptoms. When analyzing
each individual symptom, the highest mean score, of 1.68 (SD: ± 0.657), was for tingling,
followed by pain (1.65; SD: ± 0.560), weakness (1.59; SD: ± 0.727), and difficulty
picking up objects (1.11; SD: ± 0.423).
Table 5
|
Variable
|
Mean
|
Standard deviation
|
|
Overall average on the S scale
|
1.61
|
± 0.485
|
|
Average tingling score
|
1.68
|
± 0.657
|
|
Average pain score
|
1.65
|
± 0.560
|
|
Average weakness score
|
1.59
|
± 0.727
|
|
Average difficulty picking up objects
|
1.11
|
± 0.423
|
The average score on the S scale regarding difficulty picking up objects was of 1.11
(SD: ± 0.423). This value had a positive correlation with the overall average score
on the F scale (p = 0.000), showing virtually no difficulty in picking up objects. This finding confirms
that symptoms do not affect the quality of life of participants probably because their
condition is mild.
Lastly, the F scale of the BCTQ, shown in [Table 6], assessed how much these symptoms affect activities of daily living. In addition,
we calculated the mean scores for each task; the highest value referred to the ability
to carry grocery bags (1.63; SD: ± 0. 85), and the lowest value, to the ability to
shower and get dressed (1.08; SD: ± 0.34).
Table 6
|
Variable
|
Mean
|
Standard deviation
|
|
Overall average on the F scale
|
1.43
|
± 0.493
|
|
Ability to carry grocery bags
|
1.63
|
± 0.816
|
|
Ability to hold the telephone
|
1.61
|
± 0.827
|
|
Ability to perform household work
|
1.60
|
± 0.912
|
|
Ability to open a glass jar
|
1.50
|
± 0.870
|
|
Ability to write
|
1.49
|
± 0.771
|
|
Ability to hold a book during reading
|
1.40
|
± 0.663
|
|
Ability to button up clothes
|
1.14
|
± 0.348
|
|
Ability to shower and get dressed
|
1.08
|
± 0.338
|
Discussion
The average age of the participants was of 22.73 years, which is consistent with other
studies on the use of smartphones by university students, including the one by Xie
et al.,[12] in which the average age was of 23.9 years. The prevalence of females in the present
study corroborates the research by Taufiq et al.,[13] who evaluated the association between De Quervain tenosynovitis and excessive typing
on smartphones among 137 medical students, 80% of whom were female. Ali et al.[14] observed that out, of 300 students, 94% were right-handed, corroborating the present
study. The literature does not specify why most people are right-handed, but there
is a potential association with genetic, anatomical, and cultural factors.[15]
Pereira et al.[16] conducted an online survey with one hundred subjects to assess the relationship
between smartphone use and carpal tunnel syndrome; they found out that half of the
sample had been using smartphones for more than five years, confirming our data. As
for taking breaks, 58% of the participants did not do it during smartphone use. This
data does not corroborate our research, since the percentage of those who did not
take breaks was lower.
As for the distribution of daily time, Guterres et al.[5] found that most subjects (22%) use smartphones for more than 10 hours, confirming
our results. Eapen et al.[17] verified the prevalence of cumulative trauma in the upper limbs from cell phone
users and observed that 96.5% of respondents used the phone to type text messages.
In an observational study on typing postures and styles, Gold et al.[18] observed that 46.1% of the subjects held the smartphone with both hands and 36.2%,
with the right hand; in addition, 82.3% typed using the thumb, corroborating our findings.
Xie et al.[12] performed an electromyographic study and found that the upper limbs had increased
activity when typing with only one hand, requiring greater amplitude and more repetitive
movements of the thumb. These authors[12] suggested that smartphones should be held with both hands, using both thumbs to
prevent muscle overload and morbidities.
Studies on smartphone handling show that we must limit the daily use of these devices
to avoid morbidities in the upper limbs. In addition, we must use both hands and both
thumbs to hold the smartphone, take frequent breaks, avoid typing at high speed, and
support the forearms while typing.[14]
[19] In the present study, the time of daily use was consistent with the results found
by Oliveira,[20] in which 72.11% of subjects using the device for more than 10 hours had discomfort,
and there was discomfort regardless of the time of daily use.
Regarding discomfort in the upper limbs with the use of smartphones, our findings
corroborate those of the research by Oliveira,[20] in which 71.2% of college students reported discomfort in the wrist and fingers.
Eapen et al.[17] reported that 53% of subjects complained of discomfort in the thumbs, and 13%, in
the wrists. In addition, these authors state[17] that several symptoms were related to repetitive strain injuries, especially pain,
followed by discomfort and tingling. They also observed a high prevalence of pain
(61.7%). Thus, our data is consistent with the main types of symptoms presented; however,
pain was the third most frequent symptom in the present study, but the literature
indicates it as the main symptom.
Oliveira[20] reported that 71.15% of the participants complained of pain, mostly classified as
moderate (75.2%), which corroborates the level of pain found in the present study.
The overall mean score obtained by Oliveira[20] was of 1.82, which is also considered mild. Regarding individual symptoms, pain
prevailed, with the highest average (2.04), followed by tingling (average score: 1.72),
weakness (average score: 1.64), and difficulty picking up objects (average score:
1.31). These figures do not corroborate the most prevalent symptom, but are similar
to the average values, ranges, and least prevalent symptom.
Comparing the difficulty picking up objects found in the present study and the same
finding by Oliveira,[20] which was of of 1.31 on average, one can observe that they were similar, since both
samples presented mild difficulty. The scores on the F scale of the BCTQ are consistent
with those of the literature, which shows that symptoms do not affect the functionality
and activities of daily living of participants, such as in the study by Pereira et
al.,[16] who reported that subjects had no major issues or difficulty when handling a smartphone.
Conclusion
Given the aforementioned data, we conclude that there is a significant association
between the time of daily smartphone use and the presence of discomfort; smartphones
are a risk factor for the development of wrist and finger morbidities. Furthermore,
we suggest further studies to investigate not only subjective symptoms, but also physical
capacity quantitatively, as well as the muscle biomechanics of typing. This will enable
the development of more specific preventive measures, which are critical because the
incidence of smartphone-associated repetitive strain injuries tends to rise.
