Inpatient outcomes after primary total knee arthroplasty in patients receiving chronic dialysis: A nationwide propensity score-matched analysis.

BACKGROUND: Total knee arthroplasty (TKA) is widely performed for end-stage knee osteoarthritis, but outcomes may be less favorable in medically complex patients. Patients receiving chronic dialysis represent a particularly high-risk population because of chronic kidney disease-mineral and bone disorder, impaired physiologic reserve, and substantial systemic comorbidity. This study evaluated inpatient outcomes, hospital resource use, and in-hospital mortality after primary TKA among patients receiving chronic dialysis using a contemporary national inpatient database. METHODS: Adult patients who underwent primary TKA between 2016 and 2022 were identified in the Nationwide Inpatient Sample. Chronic dialysis status was defined using ICD-10-CM code Z99.2. Primary outcomes were length of stay, total hospital charges, and in-hospital mortality. Secondary outcomes included in-hospital postoperative complications. To reduce baseline differences between groups, 10:1 propensity score matching was performed using demographic, surgical, and comorbidity variables. Covariate balance was assessed using standardized mean differences. RESULTS: Among 3,423,989 patients who underwent primary TKA, 4,790 (0.1%) were receiving chronic dialysis. Before matching, patients receiving chronic dialysis had longer hospital stays, greater hospital charges, and higher in-hospital mortality than patients not receiving chronic dialysis. After matching, chronic dialysis remained associated with longer length of stay (4.2 vs. 2.7 days), higher total hospital charges, and increased risks of several in-hospital complications, including sepsis and in-hospital death. Because the Nationwide Inpatient Sample captures inpatient hospitalizations only, these findings should be interpreted as inpatient outcomes rather than post-discharge or long-term arthroplasty outcomes. CONCLUSIONS: Patients receiving chronic dialysis experienced substantially worse inpatient outcomes after primary TKA, even after adjustment for measured baseline differences. These findings support careful preoperative counseling, perioperative optimization, and multidisciplinary inpatient management when TKA is considered in this high-risk population. LEVELS OF EVIDENCE: Level III - Retrospective Cohort Study.