I'm late to this, I have done a quick read of the pages, but I'm sure I'll repeat something, so please forgive me if I do:
Sorry about your injury and new limits! I have had two knee surgeries (one on each knee) with mixed results. The first was in spring 1984, and I was told that within 25 years I would have replacement ... Not done yet thankfully. I do however have issues that arise from activities and weather.
I have learned a few things:
1. I know my limitations and remind myself of my limitations - I'm not going to out run anyone (except tt) going either direction; leg leverage is a no no; sometimes even a quick sidestep or elusive moves are impossible and even crippling, etc;
2. I have three different braces that I rely on at different times - Many on here have seen my mid-level on a few photos I posted on here, I have a light weight for more of a reminder on painful days, and I have a heavy chunk of hardware for crippled days. However, most days I just carry the braces in the suitcase and don't wear it;
3. Self defense has to be thought through every morning with regards to what my knees and shoulder are telling me - There are days where I will let people get within ten feet, because I feel agile enough to side step and react. However, there are days that my "zone" is much larger because my only physical capability is weapon, and to avoid deadly force I need much more space;
4. I also changed my "pocket pistol" due to my shoulder injury - I was relying mostly on my 1911 with a j frame back up. However, both these guns required both hands functional at some point for usage or reloads. I ended up switching (notice I didn't say trading ... I just can't give guns up any more) the j frame for an lcp. With the 1911 on the hip and the lcp in the back pocket I can do all shooting with the same hand (shoulder) and do the New York Reload only needing my bad arm to hold the empty gun. I do walk funny with most of my self defense tools on one side and only one tool on the other side, but it is what my body allows today ... hopefully in two months it will be better, but we will see.
Key these days, and I fear for the rest of my life, is that situational awareness is not only location and people, but it is my own fluctuating physical limitations.
Good luck!