Hyponatremia Is an Overlooked Sign of Trouble Following Total Joint Arthroplasty

Abstract

Background: Hyponatremia is a common electrolyte abnormality in arthroplasty patients. This issue, underrecognized by surgeons, can impact the postoperative course of patients. There are, however, little data on the implications of sodium disturbances following total joint arthroplasty (TJA). The primary aims of this study were to (1) report the rate of hyponatremia following TJA, and (2) examine the impact of hyponatremia on the perioperative course of TJA patients. Methods: This was a retrospective analysis of 3,071 primary and revision TJAs performed between 2015 and 2017. Based on preoperative and postoperative sodium values (pre-post), patients were classified into 4 groups: normonatremic-normonatremic (Group 1), normonatremic-hyponatremic (Group 2), hyponatremic-normonatremic (Group 3), and hyponatremic-hyponatremic (Group 4). Primary end points were length of stay (LOS), postoperative discharge, in-hospital complications, and 90-day readmissions. Results: The distribution of cases was 84.6% Group 1, 9.4% Group 2, 2.1% Group 3, and 3.8% Group 4. Overall, 13.2% of patients had hyponatremia after TJA. Older age, hip arthroplasty, general anesthesia, higher Charlson Comorbidity Index, congestive heart failure, revision surgery, and history of stroke, liver disease, and chronic kidney disease were risk factors for postoperative hyponatremia. Patients with postoperative hyponatremia (Groups 2 and 4) had greater likelihoods of having a 90-day complication and non-home discharge and greater LOS. Conclusions: Postoperative hyponatremia was a relatively common occurrence in patients undergoing TJA, and was associated with greater LOS, complications, and non-home discharge. Surgeons should identify patients at risk for developing sodium abnormalities in order to optimize these patients and avoid increased resource utilization. Level of Evidence: Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.