You know, when I was researching the options for fixing Molly's knee the first time, I was super frustrated and worried and could not understand why NO ONE could tell me what which option was BEST. Having been through it twice now (and with a plate removal to boot), I can understand why that best answer is so hard to come by. There are a lot of variables and I have seen claims of dogs getting back to 100% after all of the repair options (TPLO, TTA, consevative management, stem cell therapy) but I'm kind of not convinced that there is a possibility of being 100% after any of the repairs.
Here's the thing, Nelle is at 85% when she has a limping episode, and then bounces back to 100% afterwards. So if you average that out over time, she's already not at 100%. Molly is the same, she has had periods where she is at 100% and then days here and there where she isn't - and this is post surgery I am talking about. I'm okay with that, though many friends joked about her becoming "Robo-Molly" with the metal plates, she will never be as good as new.
Pain and wear on the joints get progressively worse without ANY repair after ligament damage and stability of the knee is compromised. The goal of all of the various repair options is to stabilize the knee and help mitigate additional wear on the joints. Will arthritis set in on the joint(s) that have been repaired? Yes, but if your dog can be comfortable for a period of time before that happens, is it worth it? To me, that is what the decision-making is about - making the best long term choice that works for your dog and also for you.
We don't do any dog sports with Molly (though she loved lure coursing before she blew her first knee) but we enjoy hiking and camping and wanted to make sure that Molly can enjoy that kind of outdoor time with us. She doesn't get off leash time except in the backyard - but given her prey drive and being selective about what dogs she gets along with, her off leash time was always on the limited side anyway. Of course she would love to have to more off leash time and to be able to play with her old friend (a GSP that lives near us) but their playtime was always super-rambunctious and that's not good for her. That does make me sad and we've gone through our bouts of feeling like chocolate dog owners since we deprive her of off leash fun, but when I think of the long term, I want to be able to NOT give her pain meds/NSAIDs on a regular basis to control joint pain before she turns 10.