Hi again Annette&Bert, so sorry to hear about the loss of your husband, and trust you are finding a measure of happiness again. EmmaL76 mentions that the Revitive is unsuitable for anyone with a metal implant and I have heard this. I do have a replacement knee but have found that my knee has improved using the Revitive. Before using it there was always pain in that area, but now I walk pain free and can manage three miles. Nowadays, to be outside in nature is one of my greatest joys (apart from eating!).
I think that if a lot of people with replacement knees were experiencing problems using the Revitive we would be hearing a lot more about it, but who can say what problems may arise using it long term. I'm quite happy to take that risk if it gives me mobility. I can always get a new kneecap!
Annette&Bert, remain positive. Spring will soon be with us with its drifts of daffodils and crocuses, and new growth on the trees.
Take care and stay well.