I read of studies of patients who had hip replacements. How do you know if you will get the good care if you participate in such a study?

When there is a study regarding the best way of inserting a hip replacement or the best replacement to use, the technique or implants are usually ones that have been in use already, but the researchers want to know which one seems best.

Researchers may adjust treatment plans, exercises may be offered earlier or later, or different exercises prescribed, but the goal is not to prove that one is not as good, but that the other is better.

If there is found to be a big difference between to the two, to the point that the health or well-being of the study subjects, the trial is stopped, so as not to cause harm.