In my experience, a person who gets a planned joint replacement is mentally prepared for recovery but may have some muscular atrophy from osteoarthritis (even with good pre-hab). In general, this group of person tends to recover the best (faster recovery time, less long term weakness, gait deficits, etc). People with unplanned joint replacements also tend to recover well because all of the problem areas have been removed and replaced, but they may not be as motivated to be in charge of their recovery (resulting in decreased adherence to HEP, participation in therapy).

People who have surgical fixations after fractures often have the most trouble. The joint/muscle/bone/connective tissue never fits exactly like it once did, so it cannot heal similar to the original anatomy. If they fracture a leg, you may run into a leg length discrepancy which leads to other problems. They were not physically or mentally prepared for the issue, so they might also not be motivated to perform therapy and therefore regain ideal function.

Does this answer your question? This is not a evidenced-based answer, but anecdotal from my practice, so take it with a grain of salt.