My Mother In Law Is Around 50 Year Old And

My mother in law is around 50 year old and her knee joints starts paining a lot. She is not able to walk much, not more than 100 meter that too with great difficulty. One of the local doctor has examined and suggested her to go for knee replacement. But now we all are very worried /confused because she has seen few people in her neighborhood who had gone for knee replacement but it did not work for them.

Can you please suggest us whether we should go for knee replacement or not, or is there any other alternate. If no other alternate is available then whether it is safe to go for knee replacement.

Thanks in Advance