Elizabeth Hofheinz, M.P.H., M.Ed
To get the right diagnosis, you must ask the right questions. On a macro scale, that means asking a wide range of well-thought out questions and getting them into an enormous database that is regularly mined by physicians and hospitals for the benefit of patients.
The American Joint Replacement Registry (AJRR) is the tool that fits the bill.
Joint replacement registries, in general, collect information on a combination of hip replacements, knee replacements (both total and unicompartmental), shoulder replacements, ankle replacements and elbow replacements. 
Since the first registry was established in 1975 in Sweden, there have been 31 national registries established around the world.
The early registries, almost all from Scandinavian countries, only tracked surgeon and implant performance and the main outcome collected was implant failure. Recently, however, registries are adding patient-reported outcome measures. The AJRR is adding additional dimensions to the range and quantity of data collected.
Here is a list of all the major international arthroplasty registries courtesy of the International Society of Arthroplasty Registers (ISAR).