Patients who developed postoperative hyponatremia following total joint arthroplasty had largely comparable 90-day outcomes to patients who remained normonatremic, according to a retrospective study of 4,381 inpatient primary and revision hip and knee arthroplasty cases. Although postoperative hyponatremia was associated with higher odds of medical and overall complications, the difference was largely driven by acute kidney injury (AKI). When AKI was excluded as an outcome, postoperative hyponatremia was no longer associated with increased medical or overall complications. The researchers also found no differences in surgical complications, readmissions, or emergency department visits between most sodium-status groups.