Primary Total Knee Arthroplasty in Super-obese Patients: Dramatically Higher Postoperative Complication Rates Even Compared to Revision Surgery Brian C. Werner, MD a , Cody L. Evans, MD a , Joshua T. Carothers, MD b , James A. Browne, MD a a Department of Orthopaedic Surgery, University of Virginia Health System, Charlottesville, Virginia b New Mexico Orthopaedics, Center for Joint Replacement, Albuquerque, New Mexico abstract article info Article history: Received 30 October 2014 Accepted 15 December 2014 Available online xxxx Keywords: total knee arthroplasty super obesity obesity complications revision total knee arthroplasty This study utilized a national database to evaluate 90 day postoperative complication rates after total knee arthroplasty (TKA) in super obese (BMI N 50 kg/m 2 ) patients (n = 7666) compared to non-obese patients (n = 1,212,793), obese patients (n = 291,914), morbidly obese patients (n = 169,308) and revision TKA patients (n = 28,812). Super obese patients had significantly higher rates of local and systemic complications compared to all other BMI groups as well as those undergoing revision TKA with higher rates of venous throm- boembolism (VTE), infection, and medical complications. Super obesity is associated with dramatically increased rates of postoperative complications after TKA compared to non-obese, obese, and morbidly obese patients as well as those undergoing revision TKA. © 2014 Elsevier Inc. All rights reserved. Obesity is a growing problem in the United States that affects over one-third of adults [1]. Obesity is a recognized risk factor for the devel- opment of osteoarthritis, with the knee being commonly affected [2,3]. There is nearly a three to five-fold increased risk of developing knee os- teoarthritis in patients who are overweight or obese compared to nor- mal weight patients [4,5]. The incidence of total knee arthroplasty (TKA) has paralleled the rising rate of obesity, highlighting the more fre- quent need for operative intervention as increasing numbers of over- weight and obese patients develop advanced osteoarthritis [6]. Up to 60% of patients undergoing TKA are obese at the time of surgery [7,8]. Previous studies have established a relationship between obesity and inferior outcomes and increased complications after TKA [9,10,6,11–14]. While the increased medical comorbidities associated with obesity are a significant contributor to these findings, obesity has also been independently associated with increased complications fol- lowing TKA [15]. These complications are at least partially responsible for the increase in cost of $250–300 for every 5-unit increase in BMI be- yond 30 kg/m 2 for primary TKA and an increase of $600–650 for revi- sion TKA [8]. As healthcare systems transition to bundled-payment models and the public perception of hospitals are increasingly influ- enced by state and national rankings, considerable focus has been ded- icated to risk-stratifying patients preoperatively to reduce the number of and costs incurred due to postoperative complications. This is especially important in arthroplasty, as up to half of TKAs are performed in obese patients [16]. Recently, attention has turned to an emerging population of ex- tremely overweight patients, termed super-obese and defined as those with BMI ≥ 50 kg/m 2 . While several small cohorts have sought to quantify the perioperative complication rates in this unique popula- tion during lower extremity arthroplasty, no large studies which have directly compared complications after TKA in a super-obese population to other BMI classes [14,17–19]. Furthermore, we are unaware of any comparison of risks between obese and super-obese patients undergo- ing primary TKA and those patients undergoing revision TKA surgery, which is traditionally thought to be a much riskier proposition than primary surgery. The goal of the present study is to compare postoperative complica- tion rates after TKA in super-obese patients to patients of different BMI classes as well as patients undergoing revision TKA. Materials and Methods Data for the present study were derived from a for-fee database of patients, the PearlDiver Patient Records Database (www.pearldiverinc. com; PearlDiver Inc, Fort Wayne, Indiana). The database contains proce- dure volumes and demographics for patients with International Classi- fication of Diseases, 9th Revision (ICD-9) diagnoses and procedures or Current Procedural Terminology (CPT) codes. Data for the present study were derived from the Medicare database within the PearlDiver records, which has over 100 million individual patient records from 2005 to 2011. Access to the database was granted by PearlDiver The Journal of Arthroplasty xxx (2014) xxx–xxx The Conflict of Interest statement associated with this article can be found at http:// dx.doi.org/10.1016/j.arth.2014.12.016. Reprint requests: James A. Browne, MD, University of Virginia, Department of Ortho- paedic Surgery, P.O. Box 800159, Charlottesville, VA 22908. http://dx.doi.org/10.1016/j.arth.2014.12.016 0883-5403/© 2014 Elsevier Inc. All rights reserved. Contents lists available at ScienceDirect The Journal of Arthroplasty journal homepage: www.arthroplastyjournal.org Please cite this article as: Werner BC, et al, Primary Total Knee Arthroplasty in Super-obese Patients: Dramatically Higher Postoperative Compli- cation Rates Even Compared to Rev..., J Arthroplasty (2014), http://dx.doi.org/10.1016/j.arth.2014.12.016