I have 2 meniscus tears and severe arthritis in knee. Lots of swelling too. Dr started inj again. Dr said scoping might help but won't replace knee?

Total knee. replacement surgery is a major operation with significant risk, so it should be last resort. Follow your orthopedic surgeon's advice on this one.
Total knee as option. Please think twice, even three times before pushing for a total knee. This advice from myself, a doc who is your age and already has had 2 knee replacements. The first one fell apart, the second got infected and I have been sick now for a year and have had 8 surgeries to try and get that knee back and not lose my leg! Also, in next 5-10 years much better replacements are coming out-wait for these!