Risk Factors for Greater Than 24-Hour Length of Stay After Primary Total Knee Arthroplasty

Recently, the Center for Medicare Services removed total knee arthroplasty (TKA) from the inpatient-only procedure list. The purpose of this study is to assess the role of demographics, medical comorbidities, and postsurgical complications in predicting safe discharge to home within 24 hours after TKA.

Patients undergoing primary TKA between 2011 and 2016 were identified in the American College of Surgeons National Surgical Quality Improvement Program. Patients were grouped into those whose length of stay (LOS) was less than 24 hours after surgery vs those greater than 24 hours. Demographics, preoperative comorbidities, operative variables, and postoperative adverse events were studied as risk factors for LOS greater than 24 hours.

A total of 210,075 patients undergoing primary TKA met the inclusion criteria, and of those, 18,134 (8.6%) patients were discharged within 24 hours postoperatively. In a risk-adjusted multivariate analysis, patients with increasing age, obesity, preoperative comorbidities of smoking, diabetes, dyspnea, chronic obstructive pulmonary disease, hypertension, bleeding disorder, corticosteroid use preoperatively, and dependent functional status conferred a greater risk for discharge greater than 24 hours. Male gender, spinal anesthesia, and monitored anesthesia care were protective against LOS greater than 24 hours.

This study suggests that dependent functional status, preoperative comorbidities, and postoperative complications are all associated with a LOS greater than 24 hours after TKA. Surgeons and patients should be aware of the clinical and demographic variables associated with risk for LOS greater than 24 hours when considering outpatient status for patients undergoing TKA.