What is this? Part 2

PITTSBURGH -- Any idea what this is?

It stood in the corner of the room where I had my hand x-rayed. It's some sort of orthopedic device. Perhaps it's a way of judging how well a person can step up and down.

I was having my hand checked because a golf-ball sized lump appeared at the base of my index finger, almost instantly, while I was just walking down the street:

It happened a couple of days in a row, and it bruised.

It has something to do with the band of ligaments that wrap around the base of my finger. No cause. No prevention. No fix. It just happened.

With the exception of a touch of arthritis at the base of my thumb, my hand is fine.