Are Collapsible Hiking poles in carryon luggage on international flights permitted?

No.

There have been several discussions recently here.

What controls this is not the airline, but the security. TSA specifically calls them out as not for carry on.

https://www.tsa.gov/travel/security-screening/whatcanibring/items/hiking-poles

I'm afraid you'll either have to check your bag or buy a pair of inexpensive poles when you get there and then leave them behind. Carry on only is a good goal but not always possible, or practical.

You will need to check a bag if you carry your collapsible poles.

Checking them will likely be less expensive than buying new ones in Italy. Of course, you will have to check the new ones on the way home, or leave them behind.

You could get lucky. When I was at Alpe de Suisi, there was a shop selling hiking poles for Euro 20. I left them at our hotel for someone else to use. I was more than willing to pay that for the day.
I have significant arthritis in my knees and I had surgery to remove a shredded meniscus. I have read that people are having luck carrying these trekking poles in the cabin. My plan is take one pole and use it as a cane through security. I will put the rubber tip on the end. If they confiscate the pole, I am not out much.
So, I guess it depends on what type of pole you need and how important they are to you. If you want high quality, expensive poles, better check a bag.

A FAQ with the same answer of No. See Mark's TSA link.

You may hear that some folks were able to get their trekking poles through security and into the aircraft. TSA personal have the final say, and may or may not follow the rules. (The final decision rests with the TSA officer on whether an item is allowed through the checkpoint.)

Mobility aids such as canes (without sharp points or hidden swords) are allowed on-board:
https://www.tsa.gov/travel/security-screening/whatcanibring/items/canes

If/when the TSA rejects your trekking poles you can either forfeit them for TSA disposal, or go back to the check-in counter and have your poles sent as checked baggage.

BTW Ice axes are also not allowed in the cabin and must be checked with protective covers: https://www.tsa.gov/travel/security-screening/whatcanibring/items/ice-axesice-picks

Gosh , I am glad I asked. TSA guidelines made me think that there would not be a problem, but I don’t want to lose my poles. We will be doing some hikes in Lake Como - the Varenna area, and in Ravello.
I am pretty active, but my hips sometimes need a break. I will send my poles onto Scotland with my friend who is bringing us a checked piece of luggage. I will post another question asking about hikes to Lake Como and Ravello.. Maybe the hotels will have hiking poles to rent or borrow.

I have to ask, "Why not just bring them and check your bag?"

It really isn't illegal or horrible to check a bag........

TSA officially lists them as not allowed in carryon. I see no reason to ignore.

Definitely Ck the TSA guidelines online.
That said - I’ve taken my collapsible poles in my carry on backpack to Europe TWICE without incident.

Typically no, Iowa girl 2019

Real medical assisted devices such as canes (single or double), walkers and wheelchairs will be screened at airports and major attractions and Churches in Italy. Thereafter allowed to be used.

Some may have gotten by with collapsing poles into a carry on.

Me? I would not risk it. If you get a TSA or a security agent in an International Airport who is strictly by the book -- even if your poles are seemingly necessary for balance, they may still view them as part of extra curricular activities, i.e. hiking in Nature.

One agent may allow it. As you move along in your travels, another agent may not. So, you have to ask yourself - "Is it worth the gamble?" You can chance it, but what if they are taken away? What will you do?

edited to add below

I am pretty active, but my hips sometimes need a break. I will send my poles onto Scotland with my friend who is bringing us a checked piece of luggage.

Oops, sorry Iowa girl 2019, earlier I did not see your latest reply. So that is good you can have a friend put them in their checked bag. One less thing to worry about.

My collapsible trekking poles made it fine in my carry on from JFK to Milan and back this April. I swapped out the carbide tips for the plastic ones and they passed through security without a problem. I had heard the same concerns so did some calling ahead and talked with savvy travelers. Decided to take a chance Took the chance and glad I did. My trekking poles got me up and down many a rigorous trail in the Cinque Terre. Good luck!

I did as planned and used one Hiker Hunger pole like a cane. I carried it through security, extended and put it on the belt with my luggage to be screened. I went through about 7 security screenings, 3 of them TSA. No one questioned it.

I did wear a hole through the rubber tip and had to replace it near the end of my trip. It made a huge difference to my trip and I was able to do almost everything I wanted to do. (No climbing to the tops of the Greek theatres).