Not all knee replacements are the same. Surgeons may have preferences in the prostheses they use but it in the end it is what the patients think that counts. Patients can tell the difference and have preferences for one type of knee replacement over another. This has been called the Pritchett factor based on the peer reviewed presented and published work of James Pritchett MD. The experience of the surgeons and personalized prosthesis selection transcend most other considerations such as the surgical approach or robotics. Patients and their surgeons should select the type of knee prothesis used based on the preferences and specific needs of their patients.