Economics of one-stage versus two-stage bilateral total knee arthroplasties

Patients requiring bilateral total knee arthroplasties may have both joints replaced simultaneously during one hospitalization (one-stage) or during two separate hospitalizations (two-stage). The goals of the current study were to retrospectively analyze discharge patterns for 91 patients who had one-stage bilateral total knee arthroplasties and 32 patients who had two-stage surgeries, and to quantify their in-hospital costs and their costs if the patients were discharged from the hospital to an inpatient unit. Patients having one-stage and two-stage surgery were similar in age, gender, severity of illness (as measured by the American Society of Anesthesiologists Physical Status score), principal diagnosis, and ethnicity. Using a microcosting approach, the authors found that the average in-hospital costs for one-stage total knee arthroplasty (27,468 US dollars) were significantly lower (by 24%) than for two-stage total knee arthroplasty. However, 38% of patients who had the one-stage bilateral total knee arthroplasties were admitted to an acute rehabilitation unit, which had a mean cost of 6469 US dollars and length of stay of 9 days. In contrast, none of the patients who had the two-stage procedure required acute rehabilitation. Patients who had the two-stage procedure were discharged directly home (or with home health services) 42% of the time, versus 21% for patients who had the one-stage procedure. Patients from both groups were discharged to a skilled nursing facility approximately (1/2) of the time, accruing similar costs. Economic analyses of the one-stage procedure need to consider that these patients will require increased use of acute inpatient rehabilitation after hospital discharge.