It is a problem with using stakes. Using cages rather than stakes can prevent it. But if you have to use stakes for some reason then cut notches in the stake or put in screws to keep the ties from slipping down.

But at this point just leave it be. The stem will usually scab over and compensate if no further damage is done but trying to fix it now usually does more damage.

Dave

Here is a link that might be useful: GW - Tomato Gardening forum

One of my stems got damaged when I was tying them to a trellis. I'm using old pantyhose because they are softer. Two tomatoes that were on the damaged stem got blossom end rot - gardener induced. They were still good to eat when I cut off the bad part.

Tomato stems are pretty forgiving, so if the stem isn't broken, it should recover. Dave's advice is right on. A smooth pole doesn't give the twine anything to hang on to. the heavy fruit will cause the vine to slip down. Try putting a T-type cap on the end of the conduit. Then you will have a horizontal support.

Here is a link that might be useful: What's Growing On?

I always cage my tomatoes and this year I am trying it a little different. I was using the heavy wire with square openings, maybe 5 in by 5 in openings...but the stalks grew out of them too much causing a messy looking, uncontained plant, with heavy fruits dragging those branches that stuck out of the cage down. So this year I bought the metal that is maybe 2 in by 4 in openings. It's too small to pull a tomato through when picking, but it supports the plant beautifully. I took a wire cutters and cut bigger openings around the cages, randomly. Now the plant is mostly stable with a few bigger openings that I can reach in to pick the fruit. Hope it works!

You could have just cut the tomato branches that stuck out from the cage. Keeping them well watered helps keep the stems sticking up so they don't grow out of the cage, too.