Have bilateral total knee arthroplasties become safer? A population-based trend analysis

Abstract

Background: Studies suggest a trend in the selection of younger and healthier individuals to undergo bilateral TKAs in an attempt to diminish the incidence of complications. It remains unclear whether this development has reduced overall perioperative morbidity and mortality.

Questions/purposes: We investigated whether changes in demographics and comorbidity patterns of patients undergoing bilateral TKAs are detectable and coincide with changes in length and cost of hospitalization, incidence of perioperative complications, morbidity, and mortality.

Methods: We accessed Nationwide Inpatient Survey data files between 1999 and 2008. One-year periods were created and changes in demographics, length of in-hospital stay, and perioperative morbidity and mortality were analyzed.

Results: An estimated 258,524 bilateral TKAs were performed between 1999 and 2008 in the United States. The number of annual procedures increased from 19,288 to 33,679 (75%). Length of hospital stay decreased from 4.98 to 4.01 days. Absolute in-hospital mortality rates decreased at an average rate of 10% per year. The unadjusted percent and adjusted incidence per 1000 inpatient days decreased from 0.42% and 0.85 to 0.16% and 0.39. Although the unadjusted incidence of pneumonia, pulmonary embolism, and nonmyocardial infarction cardiac complications did not change, an increase with time was detectible after adjustment for length of stay. No changes in adjusted incidence were seen for other complications.

Conclusions: Although a decreased incidence was seen for some major complications, others either remained unchanged or had an increased incidence when adjusted for length of stay. Future interventions should focus on reducing perioperative risk to improve patient safety.

Fig. 1

A graph shows the total number of bilateral TKAs with time in 1-year periods. The data were obtained from the NIS data files for 1999 to 2008. There was a 75% overall increase in the number of procedures performed per period from 1999 to 2008.

Fig. 2

A graph shows the incidence of individual comorbidities among recipients of bilateral TKAs. Data are shown for each period of study. An increase in all comorbidities was found, except for congestive heart failure, which decreased in incidence. The incidence of obesity increased by 131% during the study period. CHF = congestive heart failure; COPD = chronic obstructive pulmonary disease.

Fig. 3

A graph shows national trends in the disposition status after bilateral TKAs. The proportion of routine discharges to the patients’ customary residence without home health care decreased from 17.4% to 13.2% with time.