Risks of one-handed texting in upper-limb amputees
University of New Brunswick
This thesis details risks of one-handed texting and includes people with limb loss. The goal of this research is to help prevent repetitive strain injuries related to texting. People with limb loss may be more at risk due to overuse syndrome. 23 people participated in the study, seven with upper limb loss. The data were acquired using several instruments (on three phone sizes) including motion capture, thumb forces on the phone, electromyography, and surveys. The Limb Loss group consistently reported higher pain than the control group. Wrist extension angles while texting were 14 degrees higher in the Limb Loss group. Limb Loss participants required more time to complete standardized texting patterns by as much as 1.8 seconds longer and held force sensors for longer as well. The relative risk of conditions and texting habits were found to be significantly higher in the Limb Loss group. Texting pattern completion times decreased when the control group texted two-handed (especially on larger phones), an option the Limb Loss group does not possess. Higher thumb forces added time to completing texting patterns. Large hand sizes showed an advantage while texting in a few ways such as: lowering thumb applied forces, completing texting patterns faster, and reaching hard to reach force sensors on large phones. A larger phone size affected texting mechanics in several ways such as: increasing time required to complete patterns and an increase in muscle activation. When possible, people with limb loss should support their phone on a surface, pay close attention to their wrist posture, use an appropriately sized phone, and make a conscious effort to apply less force to the keyboard.