The Shoulder Arthroplasty Multicenter Registry for Advanced Investigation Database (SAMURAI-DB): Design and Structure of a Multicenter Shoulder Arthroplasty Registry in Japan

Background: Shoulder arthroplasty has become an increasingly important treatment option for a broad range of shoulder disorders.Although several national shoulder arthroplasty registries have been established in North America, Europe, and Australia, there is currently no well-established multicenter shoulder arthroplasty registry in Japan.To address this unmet need, researchers established the Shoulder Arthroplasty Multicenter Registry for Advanced Investigation Database (SAMURAI-DB), a multicenter clinical registry in Japan.The registry was initially launched in 2014 using paper-based case report forms and was subsequently integrated into the Research Electronic Data Capture (REDCap; Nashville, TN: Vanderbilt University) platform in 2018.The purpose of this study was to describe the design, structure, and data-collection system of SAMURAI-DB and to summarize the characteristics of procedures registered from April 2014 through December 2025.Methods: The SAMURAI-DB is a multicenter observational registry that prospectively collects clinical, surgical, radiographic, and patient-reported outcome measures (PROMs) data from patients undergoing shoulder arthroplasty.This descriptive analysis included cases registered between April 1, 2014, and December 31, 2025.Data collected included patient demographics, diagnosis, surgical procedure, implant information, complications, radiographic assessments, PROMs, and follow-up status.Registry characteristics and descriptive statistics were analyzed.Results: A total of 2,115 shoulder arthroplasties from 20 participating institutions were included in the registry.Reverse total shoulder arthroplasty (rTSA) accounted for 1,616 procedures (76.4%), followed by anatomic total shoulder arthroplasty (aTSA) (334 procedures, 15.8%) and revision rTSA (129 procedures, 6.1%).The mean age of patients undergoing rTSA was 76.9 years.The most common indications for rTSA were cuff tear arthropathy (35.1%), irreparable rotator cuff tear (31.3%), proximal humeral fracture (8.8%), and primary osteoarthritis (8.5%).Among all registered procedures eligible for each follow-up interval, outpatient visits were conducted, clinical scores were evaluated, and data were entered into the SAMURAI-DB for 70.3% of eligible procedures at six months (1,353/1,924), 76.6% at one year (1,336/1,744), and 64.8% at two years (939/1,450).Among 1,616 rTSA procedures, the most frequently recorded complications were acromial or scapular spine fracture (3.0%), instability (1.8%), implant loosening (1.6%), and periprosthetic joint infection (1.3%).Conclusions: SAMURAI-DB represents one of the first large-scale multicenter shoulder arthroplasty registries in Japan utilizing the REDCap platform.The registry enables standardized collection of longitudinal clinical, radiographic, and PROMs data across multiple institutions.The registry provides infrastructure for epidemiological research, future implant surveillance, quality improvement, and future international collaboration in shoulder arthroplasty.