I have had a knee replacement. There should be no problem with your husband's leg with a replacement knee supporting him while he recuperates. Those knees are made to be stronger than real bone. Since you can't afford a wheel chair, try looking or advertising on Craig's list for a walker with a seat in it. Look at the Goodwill stores or other used clothing stores. You frequently find walkers at these places. The ones that have a seat in them
(so that when you are tired you can turn around and sit down) might be just the thing to help you. He could sit and propel himself with his good leg; he could stand and rest his other leg on the seat, etc. We bought ours new for $120, so used should probably be about $20. Inquire at your church for a wheelchair you can borrow for 3 months. Lots of people have them that don't use them. i.e., the people who got them has died, etc. Check out garage sales. Good luck.