In reply to downsouth:
I've had it twice. First time was seven years ago in the middle finger of my left hand. Second time started just over a year ago in the ring finger. Both cases were past help from physio by the time I became aware of them. So I had the cortisone jab in both cases, which fixed it for a few months, but it then came back. I was advised that they could try another cortisone jab, but if it had come back once it would likely do so again - and there is a limit to how many times they are prepared to keep jabbing you with steroids in the same place. The first occurrence was operated on - a fairly simple outpatient procedure - and that fixed it for good. I'm on the waiting list to get the ring finger operated on but they say it might be a while - apparently there's a bit of backlog of non-critical surgical procedures at the moment for some reason...
Apparently the combination of climbing, mountain biking and playing guitar is pretty the perfect for setting it off.
(I remember when they operated on the first one, the surgeon offered to let me have a look at the inner workings of my hand before he stitched it up. I suddenly had a flashback to that scene in Star Wars where Luke Skywalker is having his cybernetic hand fitted, and politely declined. I refrained from saying that it probably wouldn't be a good idea to let me see it if they didn't want me to throw up in their nice clean operating theatre.)
Post edited at 18:21