Will pianist or typist get arthritis in fingers>what age?

Not aware of this: I am not aware that a pianist or a typist will get more or earlier arthritis than the general population, but a pianist or a typist may get carpal tunnel syndrome, especially if incorrect hand position is used.

Usually not.: You can seen many 70-80 year-old pianists, classical or jazz, palying with vigor and not showing signs of arthritis.

Over use injuries: Musicians as well as athletes, tend to have repetitive motions that can can give you musculoskeletal problems. Many times physical therapy helps.

It's not a given: Hi. No, that cannot be assumed. Many types of arthritis exist, and many factors go into developing arthritis (probably half of which are not known). I am not a rheumatologist, and they are pros at this, but I am no aware of piano playing or typing CAUSING arthritis. Obviously some of them will, but would they have gotten it anyway? Repetitive hand movements have been associated with carpel tunnel.