Knees are a great example of the bone on bone patients I see.
Patient: I'm bone on bone in both knees. The left being 100% and right being 70% bone on bone. I'm here at physical therapy for strengthening my before my total knee surgery. ME: So you getting your left knee replaced, correct? Patient: No the left doesn't hurt at all (the 100% bone on bone one doesn't hurt). I'm getting the right knee done. Me: Well that doesn't make sense does it.
This is where I learned that joints that lose motion tend to hurt.
Left knee(100% bone on bone): Full range of motion, can lock and bend knee without pain.
Right knee(70% bone on bone): Loss the ability to fully lock the knee because it hurts to lock the patient stop his/her knee from locking. The knee will continue to lose motion over time.
If the knee can't fully lock then the quad can not fully contract thus the patient is using only a small percentage of the muscle and presents weaker. Most people start standing on a bent knee and tend to hurt the longer they stand or walk. Trust me, take a closer look at older people that complain of knee pain. When they are standing does the knee look full locked? Conversely, we know a good knee can tolerate agressively locking it without pain and full weight bearing. There is a big difference between a fully functional knee and one that hurts and lacks motion.
Two months of therapy is what it took to progress the right knee to full extension and guess what no pain. The quad could work effectively and was strong and yes the knee was still 70% bone on bone. There is no pain free way to get this motion back. It a supervised therapy program that teaches the patient when, how often and how hard to push through pain to get the full motion back so the knee can work properly.
Please understand that there are some cases that do actually need a total knee but yes most of the time it can be avoided with therapy. It is definitely worth a shot if it helps you avoid surgery and in the worse case scenario, you end of getting the same surgery you were going to get anyway.