I had a few injuries through my lifting years. Some of them were so persistent I was actually off from training, particularly my tennis elbows. No matter what or how I did they just won't go away. Now, after returning to training two years ago I managed to stay almost injury-free. I had over-extended elbow from my boxing about a year ago, and that one took couple months to heal. And I also injured my shoulder from my knife throwing, this injury is 8 months old and hasn't quite healed yet.
Now, how do I train around injuries. First of all I should mention that I do 20-rep routines almost exclusively for the last two years. Can't say enough how great it works for me. Weights being just a touch lighter are VERY controllable. No injuries from lifting whatsoever. And great progress. My bench have progressed to 225 for 15 reps, can't quite do 20 yet. My leg press grew from 4 plates per side to 7 plates. I am talking nice and deep, clean 20 reps for three sets. Numbers may seem small for some of you, but those are my numbers. I wish everybody tried that, particularly those of us over 40.
Now I should also mention that there are different theories, like higher reps are only for folks on gear, natties shold do no more than 10 reps and blah-blah.