Ergonomics & Cell Phones – The Injuries at Hand

The risk of injuries associated with “hand-held devices”

Cell phones are all around us.  Casual observation in nearly any public area will confirm this.  Cell phones are a normal part of modern life and are often a daily accessory for most people.  At the start of the day, they are grabbed on the way out the door, used frequently throughout the course of a day, and are utilized through the evening hours right up until sleep.  Whether it is in the form of a cell phone, smartphone, tablet or other handheld devices, their use is ever-present. With a substantial amount of time that individuals spend on these devices, one has to wonder if there are long term consequences.  Specifically, is there a need to be concerned about musculoskeletal health spending so much time on cell phones?

It does not take a trained eye for someone to tell that posture can be rather poor while using a cell phone.  For those trained in posture and movement mechanics such as physical therapists, the potential consequences of this posture are cringe-worthy.  Postural alignment tends to curl forward over the phone. This slouched posture leads to a forward head, rounded shoulders, curved back, and a general forward bias as the user curls their body over the phone.   Mechanically, this protracts the cervical spine reducing the natural curvature of the spine. The shoulders internally rotate compromising space in the front of the glenohumeral joint. The thoracic spine goes into excessive kyphosis while slouched which places excess compression on the front of the vertebrae.  The low back (lumbar spine) curvature is also reduced as the hips rotate back into a posterior tilt with this forward posture. One would think that there would need to be a rather large force to cause this postural deficit. This is all the result however of someone bringing their head forward to better see the screen of a relatively small handheld device.  This is all that is needed to essentially displace the spine from its natural center of gravity.

What happens to the musculature when a spine is forced out of alignment?  With the human head weighing as much as a bowling ball (10-12 lbs.), this displaced weight causes considerable demand on the musculature responsible for holding the head upright.  With a forward head posture, the angle which the head rests on the neck or the head position angle changes dramatically.1   As this head position angle changes with a forward head posture, there is an increased demand on the muscles attached to the skull, shoulder blades, collar bone, and neck.  The muscles which have considerable strain put on them are the sternocleidomastoid (SCM) and upper trapezius. 1   As the curvature of the cervical spine changes with the forward head posture, the muscles are forced to work differently.  It has been shown that these changes in angle actually reduce the pain threshold for these muscles. In essence, these muscles with a forward head posture got more painful more quickly compared to those with better posture.  Correlations have been noted with this type of neck pain and increased depression.1  As one’s musculoskeletal pain increases (in this case as cervical pain increases), the psychological status changes to a detriment.  Anecdotally, working with patients with cervical myalgia, arthralgia, and muscular tension headaches can bring dramatic limitations on function and lead to a host of complaints.   

Other regions of the body besides the neck are not exempt from the postural insults of handheld device use.  Shoulder structures neighboring the neck have also shown pain with prolonged use of computers, especially among adolescent females.2,3  This pain may be attributed to the forward bias of shoulders typical while assuming a slouched posture.   The changes that accompany this prolonged positioning can contribute to impingement related conditions and alter the biomechanics of how the humerus and scapulae articulate with the surrounding joints.  Conditions include rotator cuff and bicipital tendinitis, sub-acromial impingement, myofascial pain syndrome and thoracic outlet syndrome.4

Symptoms of the lumbar spine and complaints of low back pain are documented with mobile device use.3,5 Complaints of pain in the low back seem to be less pronounced with desktop use, more pronounced with laptop use, and even more pronounced with tablet and phone use.  Assuming non-ideal postural contributes to pain, this brings some implications. The more mobile and/or small the device is, the worse the posture is while using this device.  This lends suggestion to the idea that posture tends to deteriorate with the use of smaller devices vs. desktop computers. In contrast, other studies have shown that handheld device use is associated with less low back pain compared to users of personal computers.3  However, these studies also showed that as time on mobile phone use increased (longer than 2 hours/day), the incidence of back pain and neck/shoulder pain increased significantly.  While short periods of mobile phone use may not initially contribute to low back pain, prolonged use can become provocative. 3,5   

The injuries associated with “hand-held devices” appropriately follow their namesake, with the highest incidence of injuries occurring at the hand. 4,5,6 Hand injuries claim over 80% of mobile phone related injuries.5,6  Of the hand injuries, most are associated with the thumb and index fingers, the digits most often used to hold and operate the device.  As with neck and low back injuries, the incidence of symptoms increased as time spent on the device increased. This prolonged, repetitive use has a cumulative effect and appropriately falls into the category of cumulative trauma disorders (CMD’s).   CMD’s related to cell phone and texting include tendinitis of the extensor pollicis longus, DeQuervain’s syndrome, wrist tendinitis, myofascial pain syndrome of the thenar, index, interossei and extensor muscles. 5,6   Such injuries can progress past muscle and tendon etiologies and affect deeper structures such as nerve tissue.  Paresthesia’s such as burning, numbness, and tingling associated with injury to the radial and median nerves can occur with such CMD’s. 6  Most of these injuries occur on the dominant side that is using the phone, but bilateral symptoms associated with holding the phone with the other hand can also occur.    

We can talk the talk, but can we walk to talk?  Dramatic changes have been observed in our walking (gait) pattern while talking and texting on cell phones.7,8,9  Stability, specifically, the margins of stability appears to change while walking and using a cell phone.  With this change, more side-to-side (mediolateral) room is needed to maintain stability.7  To maintain this dynamic stability with a greater side to side movement, more visual input is needed.  Ironically while looking down at a phone, we are decreasing the visual input going into our gait stability.  This, of course, increases the risk of injury. It has been shown that cell phone use among pedestrians leads to cognitive distraction, reduced situational awareness and increased injury risk.8  The dual task of attempting to text or talk while we walk may interfere with the movement patterns of our central nervous system.  This may be due to conflicting messages being sent from our thinking/cognitive (cortex) centers of the brain and the centers of the brain responsible for movement and balance (cerebellum/brainstem).   These centers may actually interfere with one another to some degree limiting stability. Such dramatic changes in straight walking (lateral deviation) can be seen while using the phone and walking, that safety is compromised.8  What is the worst of the two evils with gait stability – walking or texting?  Of the two, texting appears to have a significantly greater interference on walking and stability.  It appears that age does play a role in balance/stability while texting and walking as well. Younger adults tend to walk with more stability while texting compared to their older counterparts, regardless of the environment they were walking in.  This may sound good; however younger adults that do not change their texting and walking habits were more likely to walk into highly distracting/dangerous environments compared to older subjects. While the younger population could walk straighter, they were more likely to walk into dangerous situations.  This, in turn, could greatly increase the risk of injury by being less aware of environmental dangers.9  Injuries associated with this trauma can span the full spectrum and include fractures, tendon ruptures, traumatic brain injuries, and even death.  

There is a growing body of common knowledge about the risks of cell phone use on the musculoskeletal system.  With that comes the willingness to improve on the situation. Physical Therapy can play a crucial role in treating and preventing injuries at hand.   Assessing a patient’s ergonomic set-up can have a substantial preventative effect. Assessing not only the workspace but also the posturing while using a handheld device can yield tremendous results.  Assessing the head and neck angles to optimize spinal alignment, posture, and associated demands on the surrounding musculature are crucial. Reviewing the gaze angle by raising tablets higher to improve viewing angle is simple and low tech.  Adding a keyboard to a tablet can also improve viewing angle and demands on the hands and wrist. Simple techniques such as improving posture and educating patients on appropriate ergonomics have been shown to improve pain by as much as 75% in symptomatic populations.   Basic suggestions such as sitting with back support and maintaining neutral spine have been shown to reduce pain. Appropriately supporting the forearms to hold the phone and maintain good head position and posture are also crucial.11  Less head, neck, shoulder and finger discomfort has been shown with traditional computers vs touch screen/tablet interfaces. 11  Suggesting the use of a desktop or laptop for periods of prolonged use bring benefits compared to prolonged use on touch screen tablets.  Sensors utilizing accelerometers, gyroscopes, and compasses are being developed as we speak that monitor posture, movement and body positioning.12  In the very near future, these technologies may allow for real-time feedback from the phone on a user’s posture, ergonomics, and safety while moving.  

Use of handheld devices and smartphones are omnipresent, and the use of these products shows no sign of slowing down.  Consider asking questions about the use of these devices on your health questionnaires and patient evaluations. These phones are tools that have the capacity to do some complex and amazing things.  The power of prevention is a simple tool that we all have to keep people healthy while using this technology.

  1. Park, J., Kim, J., et. al.  (2015). The effects of heavy smartphone use on the cervical angle, pain threshold of neck muscles and depression.  Bioscience and Medical Research. 91 (3), 12-17.     
  2. Straker, L., Smith, A., et. al.  (2011). Neck/shoulder pain, habitual spinal posture and computer use in adolescents: the importance of gender.  Ergonomics.  54 (6), 539-546.
  3. Shan, Z., Deng, G., et. al.  (2013). The correlation analysis of neck/shoulder pain and low back pain with the use of digital products, physical activity and psychological status among adolescents in Shanghai.  PLOS Journal.  10, 1371.   
  4. Sharan, D., (2012).  Risk factors and clinical features of text messaging injuries.  Congress on Ergonomics. 41 (1), 1145-1148
  5. Berolo, S., Wells, R. et. al.  (2011). Musculoskeletal symptoms among mobile hand-held device users and their relationship to device use.  Applied Ergonomics.  42 (2), 371-378.
  6. Deepak, S., Mathankumar M., et. al.  (2014). Musculoskeletal disorders of the upper extremity due to extensive use of handheld devices.  Annals of Occupational and Environmental Medicine.  26 (22).  
  7. Kao, P., Higginson, C., et. al.  (2015). Walking stability during cell phone use in healthy adults.  Gait and Posture.  41 (4), 947-953.  
  8. Lamberg, E., Muratori L.  (2012). Cell phones change the way we walk.  Gait and Posture.  35 (4), 688-690.
  9. Plumer, P., Apple, S., et. al.  (2015). Texting and walking: effect of environmental setting and task prioritization on dual-task interference in healthy young adults.  Gait and Posture.  41 (1), 46-51.  
  10. Young, J., Trudeau, M., et. al.  (2012). Touch screen tablet user configuration and case supported tilt affect head and neck flexion angles.  Work: A Journal of Prevention, Assessment, and Rehabilitation. 41 (1), 81-91.  
  11. Gustafsson E., Johson P., et. al.  (2011). A technique, muscle activity and kinematic differences in young adults texting on mobile phones.  Ergonomics.  54 (5), 477-487.

Honda D., Sakata, N., et. al.  (2011). Activity recognition for risk management with an installed sensor in smart and cell phone.  Human-Computer Interaction.  230-239.  

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