I've spent 4 decades kneeling on hardwood floors and roofs and cement and generally doing damage to my knees. I thought my backpacking days were rapidly coming to an end 10 years ago, when my wife developed a balance problem. We bought poles (semi-cheap Komperdells) to help her with balance and take some strain off my knees. They worked on both counts. Now we have better grade Leki and Black Diamond. I just did a very steep up and down of 47oo feet each way and I can honestly say, I had ZERO knee pain, even coming off a winter with no bicycling for the past 6 months.
My wife had a little pain, as she had a bad fall on a rocky , icy river bank this winter, but did well with the winds howling on a narrow trail with lots of exposure. She readily will tell you, without the poles, she would not have made it. The poles are NOT only to be used by older folks, they would serve anyone well, unless your trail running. The side benefit of rigging shelters with them is a very happy bonus.
Had I known how effective they are, I would have been using them many years ago. My wife uses the BD flick locks because they are easier for her to adjust them for up and down hill without them slipping. I like my Leki twist locks, as I have a strong grip and rarely have them slip. The only ones that have failed on us was my wife not properly tightening her Leki poles and putting sideways pressure on a section that had slipped out well beyond its intended length. Not the poles fault, just an accident. The flick locks work better for her. She also says the BD grips fit better in her hand. I like my Lekis.