, Volume 471, Issue 1, pp 17-25
Date: 25 Sep 2012

Have Bilateral Total Knee Arthroplasties Become Safer?: A Population-Based Trend Analysis



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.


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.


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.


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.


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.

The institution of one of the authors (MM) has received funding, during the study period, from the Clinical Translational Science Center, National Center for Advancing Translational Sciences (NCATS) (Grant UL1-RR024996), and the Center for Education, Research, and Therapeutics, Agency for Healthcare Research and Quality (AHRQ) (Grant U18 HSO16-75). The content is solely the responsibility of the authors and does not necessarily represent the official views of the funding sources NCATS and AHRQ, Rockville, MD, USA. One of the authors (SGM) certifies that he, or a member of his immediate family, has received or may receive funding supporting research related expenses, during the study period, from the Department of Anesthesiology, Hospital for Special Surgery, New York, NY, USA. The institution of one of the authors (JP) has received funding from Zimmer (Warsaw, IN, USA), Ceramtec (Laurens, SC, USA), Orthopaedic Research and Education Foundation (Rosemont, IL, USA), Stryker Orthopaedics (Mahwah, NJ, USA), Smith and Nephew (Memphis, TN, USA), Baxter (Deerfield, IL, USA), DePuy (Raynham, MA, USA), Biomimetics (Franklin, TN, USA), Medtronic (Elizabeth, NJ, USA) and 3 M (Flemington, NJ, USA). One of the authors certifies that he (JP) has or may receive payments or benefits, during the study period, an amount of $10,000–100,000 from each of the following: Ceramtec (Laurens, SC, USA); Smith and Nephew (Memphis, TN, USA); Convatec (Skillman, NJ, USA); TissueGene (Rockville, MD, USA), Zimmer (Warsaw, IN, USA); Orthopaedic Research and Education Foundation (Rosemont, IL, USA); United States Department of Defense (Washington, DC, USA); $ Musculoskeletal Transplant Foundation (Edison, NJ, USA); The Knee Society (Rosemont, IL, USA); Stryker Orthopaedics (Mahwah, NJ, USA); DePuy (Raynham, MA, USA); Baxter (Deerfield, IL, USA); Biomimetics (Franklin, TN, USA); Wyeth (New York, NY, USA); OsteoMEM (Ladera Ranch, CA, USA); SmarTech (Atlanta, GA, USA); Elsevier (Waltham, MA, USA); Wolters Kluwer (New York, NY, USA); Slack (Thorofare, NJ, USA); Hip Innovation Technology (Plantation, FL, USA), and $100,000–1,000,000 from 3 M (Flemington, NJ, USA). Two of the authors (CBM, OS) certify that they and their immediate family have no funding or commercial associations (eg, consultancies, stock ownership, equity interest, patent/licensing arrangements, etc) that might pose a conflict of interest in connection with the submitted article.
All ICMJE Conflict of Interest Forms for authors and Clinical Orthopaedics and Related Research editors and board members are on file with the publication and can be viewed on request.
Each author certifies that his or her institution approved or waived approval for the human protocol for this investigation and that all investigations were conducted in conformity with ethical principles of research.
Analysis of Nationwide Inpatient Sample data files was performed at Weill Medical College of Cornell University, New York, NY, USA.