Form. Form. Form. Given the place of the injury and what you're trying to do, you should become a slave to your form from now on. Do weights that allow you to keep the weight, cheating it up or slight tweaks to get more weight may have been possible in the past, but now, as to not aggravate the injury or put unnecessary stress, make sure you reset your form ever single rep. That way everything is aligned and firing properly the same way.
Next comes the load, since you're trying to strengthen it, build-up, by 2.5, 5 to 10lbs or each side, every set, just to find where your form breaks down when you feel it about to break, go back about a step or two and call that your home for a while. Find a weight you can do 8 to 12 times comfortably for as many sets as you can. I prefer 5 sets of 8 to 12 at working weight. Every two weeks do that build up. Warm-up, get to your work out weight, do one set there, then go up by 5 or 10 lbs, do a set there and continue, till you feel the form breaking down, make a note of it and then do the process above. Be mindful of your knees, if they feel off don't deadlift, if you feel something weird while doing a deadlift, I would stop. At the end of the day your body will be your guide, listen to it and be overly cautious. There are other exercises that can help, Calf Raises, Leg Presses, Wall Squats, they can all help the knees.
Please note, I did not say to max out, I recommended that you reach a working set where your form starts to fail, meaning you will be far from your max weight. Given the injury, maxing out is probably not something you should risk. But the rest of the typical exercise regiments can be followed as long as the strictest form is applied to ensure you're not putting any undue stress on the joints.