One of our dogs had TPLO surgery on one knee and a tightrope procedure on the other (both for ruptured cruciates). She also dislocated one kneecap, which is a known, but very rare complication of cruciate surgery.
In all, she was on cage rest or gradually rehabilitating for about a year - 9 weeks cage rest after the first op, then a few weeks of gradually increasing walks, then the second op, and another 6 weeks cage rest, and finally the dislocation, which also required surgery, and longer cage rest - 9 weeks plus, if I recall.
She was on a programme of gradually increasing walks - initially only 10 minutes, twice a day - we barely got to the end of the road, but she did get back to almost 100% of her previous activity levels. We weren’t offered physio for her, and I wish now we had pushed for it, because she did develop arthritis in later life, which might have been delayed if she had had the physio after the surgeries. She did have hydrotherapy later in life, and I wish we had got her that earlier.
She was a large breed dog - a lab-pointer cross - so we couldn’t carry her out to the garden to do her business, in the cage rest periods, so the vet hospital advised using a sling under her tummy to support her back end, so she wasn’t putting too much weight on the knees, or risking slipping. We found she really didn’t want to do her business on the lead, and we were told she mustn’t be left off lead in case she decided to run or jump. In the end, we used plastic netting and stakes to make her a small enclosure on the lawn that we could let her into, off lead, but wasn’t big enough to run in.
The vets did offer to sell us a sling for taking her to the garden - but it cost something ludicrous, so I wrapped a towel round a spare lead and tacked it in place, and used that.
I was worried that she would fret, when she was on cage rest, because she was a very active dog, but she settled with no problems - I think she understood it was for her benefit. We put the cage in the front room, so she could see us for a lot of the day.