Might consider Push- Pull type workouts on different days. Based on 3 work days a week. Allowing a full days rest between those workout days.
Example:
Monday...Push, including the 3 positions of a complete push range
Bench- pushing straight out from the body
Dips- pushing down and along side the body
Overhead Press- pushing up and above the body
Add a triceps exercise if you wish
Wednesday...Pull, 3 positions of the complete pull range
Chin or lat pulldown- pulling down to the body
Bent over rows (BB or DB)- pulling straight into the body
Up-right rows- pulling up and along side the body
Add a bicep exercise if you wish
Friday...repeat Mondays press workout
The next Monday switch to the Pull workout, Wednesday the Press workout, Friday the pull workout. The following Monday back to the Press workout, etc.
Suggest 2 or 3 sets each exercise. Reps 6-10. If you worry about the delts they will get hit hard by the overhead presses and the uprights. Both mass producing movements.
Wonder if Nunzi has ever used the rehab leg machines that have the resistance on the back/hock of the knees. This reduces most of the stress on the knee's themselves.Used either lying or sitting. Something like the original Art Jones designed leg-back machine. Some let you use one leg at a time. Or sitting on a bench and doing GoodMornings. Or hyperextension bench workouts..Good luck.