Having knees older than the previous mentioned ones I have given this much thought and some research over the last ten years. Knees wear out , some faster than others due to genetics and some due to accidental wear. The mechanism of wear is a reasonably hot research topic and the answers are far from clear. Intuitively it would seem that stress on the cartilage would be proportional to wear and this is true to some extent between high impact and low impact sports.
In terms of riding brakeless It feels to me when when i ride 45/17 that the torque generated climbing a 12 percent grade is much more than generated skid stoping. A biomechanical friend of mine and I spent a day with wax plates stuck on the pedals and the preliminary findings supported the feeling that riding uphill generated more stress. We have never got around to doing this formally but it is back burner project,
Having done minor meniscal tears it was my experience that keeping on riding and doing the exercise physio stuff the injury eventually settled down . I would make sure you did not have any complicating factors like a tendency towards gout etc.It would be sensible to step the gearing down some .
Therefore it is my advice supported by alcohol fuelled conversations with orthopaedic surgeons that you keep riding regularly, that you seek physio support, that you get checked out for things that can decrease your healing like uric acid, vitaminD , homocysteine etc. The evidence for the long term advantage of arthroscopy and debridement is pretty poor but is advantageous in the short term . If you are being paid a million dollars per year to ride then get your meniscus and cartilage trimmed and get back on your bike but no one will suggest that your knee will be better off in 30 years than someone who did not
I would also add that I would not be riding brakeless if my knees were not trust worthy. It is one thing to say ouch grinding up hill it is a totally different experience to feel that pain as you try to avoid sliding under a bus
Ps never had a power band I was more a reggae type