Incidence and 30- and 90-day readmission rates after primary shoulder arthroplasty in the United States: an analysis using the National Readmissions Database.

Background: The field of shoulder arthroplasty has experienced a substantial increase in the number of procedures performed annually and a shift toward more common implantation of reverse shoulder arthroplasties (RSAs). Same-day discharge is perceived as beneficial for most patients as well as our health care system, and the number of shoulder procedures performed as same-day surgery has increased substantially. However, the potential benefits of same-day discharge after shoulder arthroplasty may be negatively influenced by unexpected readmissions. As such, an in-depth analysis of readmission rates after primary shoulder arthroplasty is particularly timely.

Methods: The National Readmissions Database was queried for primary shoulder arthroplasty procedures performed in the United States between 2016 and 2018. National incidences were calculated, and indications, patient demographic characteristics, comorbidities, facility characteristics, and rates and causes of 30- and 90-day readmissions were determined for all procedures and compared between anatomic total shoulder arthroplasty (TSA), anatomic hemiarthroplasty (HA), and RSA.

Results: During the study period, 336,672 primary shoulder arthroplasties were performed (37% TSAs, 57% RSAs, and 6% HAs). In 2018, national incidences per 100,000 inhabitants were 22.64 for RSA, 12.70 for TSA, and 1.50 for HA. The utilization of these procedures between 2016 and 2018 increased for RSA, decreased for HA, and remained constant for TSA, but these changes did not reach the level of statistical significance. The average all-cause 30-day readmission rates were 3.63%, 1.92%, and 3.81% for RSA, TSA, and HA, respectively, and the average all-cause 90-day readmission rates were 7.76%, 4.37%, and 9.18%, respectively. For both RSA and HA, the most common surgical diagnosis for 30-day and 90-day readmissions was dislocation (0.45% and 0.99%, respectively, for RSA and 0.21% and 0.67%, respectively, for HA). For TSA, the most common surgical diagnosis for 30-day readmission was infection (0.11%); however, this was surpassed by dislocation (0.28%) at 90 days.

Conclusion: RSA surpassed TSA as the most frequently performed shoulder arthroplasty procedure in the United States between 2016 and 2018. During this period, the 90-day readmission rate was not negligible, with dislocation and infection as the leading orthopedic causes of readmission.