MODEL RELEASED. Mobile phone texting. Teenage girls typing text messages on their mobile phones. Repeated use of the thumb to type messages has led to a rise in RSIs (repetitive strain injuries) of the thumb in children. This is commonly felt as pain in a joint that is subjected to repeated movements. The exact disorder varies from case to case, ranging from tendon sheath inflammation to nerve compression from such swelling. Treatment involves cessation of the repeated movement that caused the RSI. Text messages are sent using short message service (SMS) technology. These phones have been personalized with customised covers.