I'm surprised you aren't doing some form of formal physical rehabilitation. I had the ACL rebuilt in my left knee back in 1998, and it took me about a year of consistent physical therapy and exercise before I felt close to 100%. There are no tricks - just daily, dedicated, and properly directed work.
The Camino is very hard on feet and joints - you'll be walking with weight on some harsh terrain for long distances. I would talk over your Camino plans with your doctor - perhaps he/she can better evaluate your Camino fitness and suggest a timeline or training path. If you get the green light, then ideally you should prep for the trek (walking with your boots and pack, for example). Also, you may need to wear some kind of brace to ensure stability. And after all of that, the best thing you can do is allot plenty of time to do the Way. No one should rush, but someone in your condition needs extra time to do it.
I'm in pretty good shape (I box and teach martial arts), but the Camino kicked my butt (especially since I had too much weight initially and my boots were too heavy). I ended up having to slow down to 10 -12K a day for about a week and a half after my first two days on the trail (leaving from St. Jean) due to foot pain (I have flat feet) and blisters. If I hadn't been able to take extra time, then I probably would've failed, or at least taken a bus/train for part of the way. And I greased my wheels with ibuprofen tablets and gel, along with vino tinto (hence my nickname). I'm not recommending getting blotto, but pain management is important. ;-)
Eventually I was able to go farther and faster, especially after I got rid of some stuff and got better boots. But I still took break days here and there to recover, and 40 days after I started I finally walked into Santiago. So, the three best things I can recommend are 1) rehab and train before you go, 2) pack light and get the right equipment, and 3) allot plenty of time to do the Camino so you can rest (and just have fun here and there). Folks who rushed were the most prone to fatigue and injury.
Here and there on the Camino I would run into a retired Norwegian with two artificial knees who began his trek in Le Puy. Even after twice falling down some albergue stairs, he still soldiered on, and the last time I saw him he was two days out from Santiago. So I'd say if he can do it, then so can you, because ultimately your head and heart will be the deciding factors on whether or not you complete the Way - Buen Camino