From my experience as a PT working with many people who have undergone joint replacements, the most common statement I hear is that they can't understand why they are so weak after surgery. They usually were prepared for some general weakness and fatigue, but not for their limb to be so weak and impaired. Instead of arthritic pain, they now have the pain from the surgery. The best advice I can give, is to tell people to strengthen the joint and surrounding muscles as much as possible prior to the surgery. The more strength they have before the surgery, the better and faster they'll recover after the surgery. Check with your orthopedist, and request a pre-surgery PT session to learn the appropriate exercises. For example, learn to do a quad set before a hip or knee replacement. It is much easier to learn to do a quad set when you can see your thigh and focus on the movement of the patella, than to try to learn how to do a quad set after your knee or hip has been opened, bandaged, is painful, and swollen.

I hope this helps.
Amy Wright, PT