This is all the normal shock from returning to workouts: the soreness, the tiredness, etc.:
-Take days off till the soreness is gone.
-It's better to ease into the first couple of workouts by not doing as many sets and not pushing to max., until the initial soreness after the first workout(s) passes, then ramp up.
-Make sure you're taking the time to warm up thoroughly, even more important when coming back.
-Keep the reps 8-10, especially at the beginning, to put the stress on the muscles instead of the joints. Any exercises that continue to create joint stress should be replaced by variations of the same exercise, and if that's not enough, by substitutes that hit the same muscle without the negative joint problems.
-Your strength will come back after the break-in period, as you regain a sense of balance. After that, the long break you took should provide the freshness & energy to work up to and exceed what you were doing before. Just give it time to get up to speed, no hurry.
-Hot baths or showers will help reduce the soreness as will light activity like walking.