I had 2 TKRs 2-3 years ago (one at 66 and one at 67). While I haven’t been the “competitive athlete my whole life” I have been very active living on a small farm with animals and never-ending maintenance stuff.

My experience is that the recovery was very painful and, at times, discouraging. My mom was an ortho nurse as her last job before retirement and had a TKR at 78. Before she died, we discussed my coming TKRs many times (arthritis). What she told me was to push through the pain and, if the PT asked for 10 reps, do 12-15 (I called these extras the “angel’s share”.

Point is, summon your competitive spirit and work harder than you’ve ever worked before. My surgeon/friend told me that I’d never confuse his work with my God-given knees. That’s true. I stretch them every night before bed and, some nights, it still is mildly painful but nothing like pre-op. I also sprinkle in weights and yoga weekly. You’ll get back what you pay in, imo.

While I can’t speak directly to the impact on competitive tennis, I can say that, with diligent work, you are and will be significantly better than pre-op. At 69 I’ve tried to learn to modify if I can’t (or shouldn’t) do something. I plan to have many more years and sitting on the couch isn’t and won’t be part of my agenda. It reward.

Keep working. Good luck to you!