Electrolyte imbalance after total joint arthroplasty: risk factors and impact on length of hospital stay

Background Clinical as well as subclinical hyponatremia is frequently seen after orthopedic surgery. The study was aimed to determine the frequency and severity of hyponatremia in a cohort of total joint arthroplasty cases and identify the risk factors and their impact. Methods This is a retrospective observational study of 546 consecutive cases of total joint arthroplasty patients from a single institution. Only primary hip and knee replacements were included. The study was approved by the institutional review board. Preoperative and postoperative serum electrolytes were recorded till 45-day review. This was correlated with the age, gender, BMI, drug intake, and comorbidities. Results We identified 84.9% postsurgical hyponatremia in our cohort. Of these 80% were mild, 16% moderate and 4% severe. Preoperative hyponatremia was a consistent finding in most severe cases. Thaizides, ACE inhibitors, and longer surgeries like bilateral TKRs had more hyponatremia. Hospital stay was not impacted in this study for reasons discussed. There were no deaths in this series during the follow-up period, but two patients were rehospitalized. Conclusion Postsurgical hyponatremia occurs in up to 85% of primary hip and knee arthroplasty patients. The most consistent predictor of severe electrolyte disturbance postsurgery is preoperative hyponatremia. Older age, female gender, longer surgery, and drugs like thiazides and ACE inhibitors seemed contributory.