[faultytowers]

Both Phuket International Hospital ,and Bangkok Phuket Hospital have very good reputations and are probably (in my opinion) better than a lot of UK hospitals. I know people who have had Orthopaedic surgery there and have had first class results , standards of care are very high and medical/surgical treatment is excellent.

Can't actually comment on knee replacement surgery , as it can vary depending on amount of degeneration in the joint , but they can now do total/partial joint , so it would be up to the doc to decide what's necessary.
"Normal" total knee replacement (one knee) usually takes about 2-3 hours, lots of physiotherapy after-wards ( not my field , so not sure how long).

My advice would be to get as much information you can from your mother's doctor , and then e-mail both hospitals and see what they offer. India may be cheaper , and I cannot comment on the hospitals there but I would have surgery in Phuket if I had a choice. And as someone who works in Operating Theatres , I hope I never need to , LOS is for my holidays so the last place I want to end up is "on the table".