and I did squats. Luckily I noticed the knee effect and switched to the treadmill.

I think controlled lunges might be okay? But the general point seems to be not
to overuse the mechanical movement of the knee under pressure.

Maybe base this on age. After 50 modifications might be in order.

I'm a big walker and because of a weak ankle, I keep the speed much lower than I used to--usually consistently 3.5 mph. And I still use my Nordic Track, but i really need to think about another supplementary activity for bad weather--besides exercise videos and free weights....

the last one I was using was weighted in a way that would pull on my knee.

The treadmill seems more reliable -- plus the butt gets exercise, although I just walk.. kinda fast.

I pulled ligaments in my hip and though it healed it doesn't like going to fast, but after not being
able to walk for a couple of weeks mobility is very nice!

When it comes to the wear and tear of a joint leading to osteoarthritis, I would have to say doing lunges would fall into that same category as squats would considering it is a weight bearing exercise with a large range of motion performed by the knee joint. A key to avoiding knee injury when performing static or walking lunges is to ensure that the front knee is NEVER sticking out front beyond the toes as it will lead to knee injury. As well, ensure the back foot is straight back ie. the heel is not rotated inwards or outwards, but rather in line with the rest of the body.
Apparently the largest contributing factor to knee pain is due to a muscle injury or imbalance of the thigh muscles (or quadriceps) as they have four heads that insert into and stabilize the knee. Keeping these muscles strong helps to avoid knee problems, however it seems that many exercises for these muscles involve wear and tear of the knee. Is it best not to exercise the legs at all then? Absolutely not!
Stretching and strengthening exercises help maintain healthy cartilage, increase a joint's range of motion and strengthen surrounding muscles which allows them to better absorb shock. These types of exercises help to prevent and are also used in the treatment of osteoporosis. Good low-impact examples of these exercises would be yoga and the use of resistance bands.

It all rings true. As I said above I pulled ligaments in my hip due to a rotated pelvis, and due to that having been rotated for years without my knowledge and now having weakness due to the pull on one side, that one knee is having problems. It's out of alignment somehow I agree strength is the answer, plus stretching if you know what you're doing. The PT said that for me strengthening is important but it's hard to do without really knowing what could cause more damage. I used to use the inverted vertical machine with 45 lb weights, and he said that would be okay to do again .. but I intuitively knew it was too much for the knee. Now I'm trying to figure out how to strengthen my lower body without harm to knees or hip.

I am doing side leg lifts but it's so slow to gain strength with that. I guess what I'm trying to identify is how to strengthen quadricep hamstring without damage to the knee or too much strain.. that's harder than I thought.

Forget lunges for me -- I can hear my knees complaining and form has to be so perfect. I think it's a bit better done in a rack set up if at all. With this kind of ligament issue separating the legs is a no no as it induces torque.

That makes sense. Plus it's a great workout.

I don't think proper technique would be enough for someone with knee problems. If you have research on that I'd like to read it -- because I'd like to do more weights for my lower body -- but the idea one could make it worse sounds probable.

If we're talking about only osteoarthritis, then we have to know how much cartilage has been lost and whether there are any other conditions caused or exacerbated by the arthritis.

It is always of great benefit to enhance the proprioceptive response and stabilizing capacity of the muscles around any joint. Basically, proprioception is the musculature's 'awareness' of the body and what it's doing. By giving the muscles challenges, like walking on loose sand, the ability of the neuro-motor system to coordinate is augmented and the muscles become conditioned.
That way, one finds they compensate for the pain less with posture and more with muscular stabilization.

Yes, you know this already. But definitely talk to your doctor about any program you might try out. No matter how much sense someone seems to make on the internet, it's always best to go face-to-face with someone you know and trust.

For me, proper squats (knees NEVER protrude forward of toes) are excellent for keeping my arthritis from slowing me down.

Good luck with whatever program you use.

Now when I walk carrying groceries, my improvised weight bearing exercise, isn't that good for my knees and bones?

Then why do they get on overweight as being extra weight on the bones, for every pound of weight it's four on the knees or somethng..
I would think extra body weight would then condition the knees -- make them grow more cartilidge or whatever weight bearing does?