And for those of you who are still interested in the initial topic of the post, Arthrogryposis is a term used to describe a number of rare conditions characterized by stiff joints and abnormally developed muscles. It is not thought to be a genetic or hereditary condition and the exact cause of arthrogryposis is still unknown.
There are, however, a number of different theories, proposed to explain it. One states that arthrogryposis is caused by obstructions to intrauterine movement during pregnancy, another says that it may be a result of an early viral infection during a baby’s development while the third one assumes that arthrogryposis is the result of failure of the central nervous system and/or muscular system to develop appropriately.
In OP’s case, he lacks the strength to bend his fingers at the top two joints (making a fist). “I can still move and bend them otherwise and I have full range if motion everywhere else,” he wrote. “I have a pretty mild form of Arthrogryposis, so [for example] typing isn’t difficult strength-wise at all.”
“I’ve adapted quite well,” he continued. “Certain things are difficult, such as opening bottles or cans (I’ve kind of been using my teeth to do this for a while, and I really should stop that). I hold heavy bags in an odd way since I cannot grip them normally. I usually rest them on the top of my hand and bend it upwards at a 90-degree angle. I probably do other weird things too that aren’t coming to mind at the moment. Most people aren’t aware of my disability because I don’t really bring it up and I’ve adapted quite well to it.”