National joint replacement registries assist surgeons and hospitals with guiding decision making and quality of care. The data points collected are essential to interpret and analyze data and to understand confounding variables and other sources of bias, which can impair retrospective observational research. The aim of this study was to review all national joint replacement registries to assess what data points are recorded, and in what manner, for primary and revision total hip arthroplasty (THA) and total knee arthroplasty (TKA) so that improvements can be made to enhance data collection, interpretation, and analysis.

All national registries were identified through Internet and publication search and contacted to invite participation. Data collection forms for both primary and revision THA and TKA were requested. Data collected were entered into an Excel spreadsheet.

The study group for primary and revision THA consisted of 28 national registries, with 26 agreeing to participate. The study group for primary TKA consisted of 27 national registries, with 24 agreeing to participate. Patient identification details were recorded uniformly. Only a minority recorded patient details beyond American Society of Anesthesiologists and body mass index. Most registries did not record surgeon variables: who actually performed or assisted the procedure and their level of training. There was variation in the degree of detail recorded for diagnosis, mostly regarding secondary causes of osteoarthritis and fracture. The details regarding case complexity were limited. Half recorded previous operations, and fewer recorded bone defects. The location of knee arthritis, preoperative limb alignment, and deformities were rarely recorded. Surgical approach and technological adjuncts were routinely collected, but few other details on the surgical technique were recorded. Implant details and fixation were uniformly collected, although a minority recorded specific details, including cement antibiotic or cementing technique. It was uncommon to record whether additional or adjunctive procedures were concurrently performed. Approximately half the registries lacked a revision specific form. The majority recorded reoperations in addition to revision procedures. Patient, surgeon, case, and postoperative details were recorded similar to primary procedures. There was variation in the degree of details recorded for the reasons underlying the revision +/− reoperation, with most recording greater detail for infection and fracture. Many included details on case complexity and bone defects, including the severity, classification, and how the defect was managed. The majority recorded the specific revision procedure that was performed (total or partial), the fixation used, and the components removed or revised. Other specific aspects of fixation including acetabular screws, cone or sleeve use, stems, and augments were less commonly recorded.

Substantial data are recorded by all registries, although each one is different. Data solicited lack many patient factors, surgeon variables, case complexity, and surgical techniques. Separate revision forms are not universal, and many registries do not record reoperation procedures, specific causes of revision, and the revision construct.

Level II, therapeutic study. See Instructions for Authors for a complete description of levels of evidence.