It seems that with every bit of new technology comes some form of social or personal cost. Often times that personal cost resolves itself in the form of a repetitive stress injury. Cell phones are one such technology.
Socially and culturally, we are dealing with constant interconnectedness as well as inconsiderate users who feel they should talk wherever they are, regardless of the people around them. But this isn't about etiquette. This is about ergonomics.
The cell phone has led to some health conditions, but it wasn't until the invention of supporting technologies - mobile data, cellular email, and the almighty text message - that the repetitive stress became a real problem for most users. Text messages have some great advantages and have changed our culture, but the input method leaves a lot to be desired. And that is what leads to Texting Thumb.
Texting Thumb is a repetitive stress injury that affects the thumb and wrist. Pain and sometimes a popping sound are present on the outside of the thumb at or near the wrist. There can also be a decrease in grip strength or range of motion.
You see, the opposable thumb is very good at performing opposing actions to the hand and fingers, otherwise known as gripping. The muscles and mechanics of your anatomy support this function. The thumb acts as the lower half of a pair of pliers. It is much better at this than dexterous three-dimensional motions, like typing. That puts a lot of repetitive stress on the thumb joint and the muscles and tendons attached to it.
The thumb is sufficient to press a key on your phone's keypad without much stress being placed on it. It is mainly the traveling the thumb tip does over the keypad, which is often a couple of square inches. This is a lot of work on a joint that, quite frankly, isn't designed to move that much.
Cell phones that have a standard number pad often use a predictive text entry or other methods to make input easier without scrolling through all the available letters for each number. This helps a lot but not enough to counteract how often most people text.
Smartphones are even worse. While they do have full keyboards to make input easier, they have larger surfaces for the thumb to travel over and can often involve both thumbs. What's more, the ease of input actually makes it more likely for you to type in real words instead of the texting shorthand.
Texting Thumb can be a form of tendonitis, tenosynovitis, or a combination of both of those disorders. In either case, it means something is irritated, inflamed, and swollen. In Texting Thumb, there is an inflammation of the tendons and/or the synovial sheaths that cover the tendons that control the motion of your thumb. It may also be an inflammation in the tenosynovium, a slippery membrane that acts as a sliding surface, in the opening in the wrist that the tendons slide through. Often the swelling from the inflammation in either the tendon or tenosynovitis causes irritation that leads to inflammation in the other after repetitive use. It can be quite painful and reduces your ability to grip.
Whichever part of the anatomy is irritated and inflamed, it squeezes the tendons and constricts their ability to slide within the sheath. The inflammation results in swelling and pain that can run from the tip of the thumb all the way down to the wrist and even the upper portion of the forearm.
In Texting Thumb, you often feel the pain when you turn or flex your wrist or when you make a fist or grab something. It often occurs in gamers who play daily for long periods.
The Technical Explanation
Texting Thumb is technically known as De Quervain's syndrome. There are many aliases for De Quervain's syndrome with one in homage to the one-time mobile data king, Blackberry Thumb.
If you flatten your hand out with the back of your hand downward, then your thumb can move in two ways. It can move up and back down. This moves your thumb out of the plane of your hand and is called palmar abduction. Your thumb can also move left to right, staying within the plane of your hand. This type of movement is called radial abduction.
These tendons are housed within synovial sheaths through the wrist passage. Synovial sheaths are kind of like a stiffer, outer tube that can bend but does not kink. The result is that when the wrist is bent or twisted, the tendons can still slide back and forth through the wrist passage without getting snagged.
The tendons pass through an opening in the wrist on the thumb side. This opening is covered in a slippery membrane called tenosynovium. Constant friction against this surface by inflamed synovial sheaths can cause inflammation in the tenosynovium as well. Inflammation of a tenosynovium is called tenosynovitis.
The tendons involved in De Quervain's syndrome are those attached to the extensor pollicis brevis and abductor pollicis longus muscles, or the muscles that move your thumb in radial abduction. The muscles run side by side on the back of your forearm towards your wrist and the tendons run along the thumb, from the tip to your wrist through an opening in your wrist where they then attach to the muscles.
In De Quervain's syndrome, irritation from repetitive stress causes the inflammation in the tendon or synovial sheath, which leads to swelling and enlarges a portion of the tendon making it difficult for the tendon to pass through the opening in the wrist. Or it causes inflammation in the tenosynovium, which results in the same thing. Often, when one is swollen, it causes the other to become irritated and inflamed as well, thereby compounding the problem.
Take Care of Yourself!
If left untreated, Texting Thumb can worsen and the repetitive inflammation and irritation of the tendon's synovial sheaths cause them to thicken and degenerate. This can result in permanent damage, leading to a loss of grip strength and/or range of motion as well as constant pain.
De Quervain's Syndrome can be treated at home effectively if it has not gotten that severe. If you are a serious texter you should consider trying to prevent De Quervain's syndrome to keep your hand healthy.