Association Between Body Mass Index and Thirty-Day Complications After Total Knee Arthroplasty

Published:October 06, 2017DOI:



      Although previous studies have evaluated the effect of obesity on the outcomes of total knee arthroplasty (TKA), most considered obesity as a binary variable. It is important to compare different weight categories and consider body mass index (BMI) as a continuous variable to understand the effects of obesity across the entire range of BMI. Therefore, the objective of this study is to analyze the effect of BMI on 30-day readmissions and complications after TKA, considering BMI as both a categorical and a continuous variable.


      The National Surgical Quality Improvement Project database was queried from 2011 to 2015 to identify 150,934 primary TKAs. Thirty-day rates of readmissions, reoperations, and medical/surgical complications were compared between different weight categories (overweight: BMI >25 and ≤30 kg/m2; obese: BMI >30 and ≤40 kg/m2; morbidly obese: BMI >40 kg/m2) and the normal weight category (BMI >18.5 and ≤25 kg/m2) using multivariate regression models. Spline regression models were created to study BMI as a continuous variable.


      Obese patients were at increased risk of pulmonary embolism (PE) (P < .001), while morbidly obese patients were at increased risk of readmission (P < .001), reoperation (P < .001), superficial infection (P < .001), periprosthetic joint infection (P < .001), wound dehiscence (P < .001), PE (P < .001), urinary tract infection (P = .003), reintubation (P = .004), and renal insufficiency (P < .001). Transfusion was lower in overweight (P < .001), obese (P < .001), and morbidly obese (P < .001) patients. BMI had a nonlinear relationship with readmission (P < .001), reoperation (P < .001), periprosthetic joint infection (P = .041), PE (P < .001), renal insufficiency (P = .046), and transfusion (P < .001).


      Obesity increased the risk of readmission and various complications after TKA, with the risk being dependent on the severity of obesity. Relationships between BMI and complications showed considerable variations with some outcomes like readmission and reoperation showing a U-shaped relationship. Based on our findings, a potential BMI goal in weight management for obese patients could be established around 29-30 kg/m2, in order to decrease the risk of most TKA postoperative complications.


      To read this article in full you will need to make a payment

      Purchase one-time access:

      Academic and Personal
      One-time access price info
      • For academic or personal research use, select 'Academic and Personal'
      • For corporate R&D use, select 'Corporate R&D Professionals'


      Subscribe to The Journal of Arthroplasty
      Already a print subscriber? Claim online access
      Already an online subscriber? Sign in
      Institutional Access: Sign in to ScienceDirect


        • Mokdad A.H.
        • Serdula M.K.
        • Dietz W.H.
        • Bowman B.A.
        • Marks J.S.
        • Koplan J.P.
        The spread of the obesity epidemic in the United States, 1991-1998.
        JAMA. 1999; 282: 1519-1522
        • Fehring T.K.
        • Odum S.M.
        • Griffin W.L.
        • Mason J.B.
        • McCoy T.H.
        The obesity epidemic: its effect on total joint arthroplasty.
        J Arthroplasty. 2007; 22: 71-76
        • Losina E.
        • Thornhill T.S.
        • Rome B.N.
        • Wright J.
        • Katz J.N.
        The dramatic increase in total knee replacement utilization rates in the United States cannot be fully explained by growth in population size and the obesity epidemic.
        J Bone Joint Surg Am. 2012; 94: 201-207
        • Haverkamp D.
        • Klinkenbijl M.N.
        • Somford M.P.
        • Albers G.H.R.
        • van der Vis H.M.
        Obesity in total hip arthroplasty—does it really matter? A meta-analysis.
        Acta Orthop. 2011; 82: 417-422
        • Liu W.
        • Wahafu T.
        • Cheng M.
        • Cheng T.
        • Zhang Y.
        • Zhang X.
        The influence of obesity on primary total hip arthroplasty outcomes: a meta-analysis of prospective cohort studies.
        Orthop Traumatol Surg Res. 2015; 101: 289-296
        • Kerkhoffs G.M.
        • Servien E.
        • Dunn W.
        • Dahm D.
        • Bramer J.A.
        • Haverkamp D.
        The influence of obesity on the complication rate and outcome of total knee arthroplasty: a meta-analysis and systematic literature review.
        J Bone Joint Surg Am. 2012; 94: 1839-1844
        • Pi-Sunyer F.X.
        Comorbidities of overweight and obesity: current evidence and research issues.
        Med Sci Sports Exerc. 1999; 31: S602-S608
        • Adhikary S.D.
        • Liu W.-M.
        • Memtsoudis S.G.
        • Davis C.M.
        • Liu J.
        Body mass index more than 45 kg/m2 as a cutoff point is associated with dramatically increased postoperative complications in total knee arthroplasty and total hip arthroplasty.
        J Arthroplasty. 2016; 31: 749-753
        • Baker P.
        • Petheram T.
        • Jameson S.
        • Reed M.
        • Gregg P.
        • Deehan D.
        The association between body mass index and the outcomes of total knee arthroplasty.
        J Bone Joint Surg Am. 2012; 94: 1501-1508
        • D’Apuzzo M.R.
        • Novicoff W.M.
        • Browne J.A.
        The John Insall Award: morbid obesity independently impacts complications, mortality, and resource use after TKA.
        Clin Orthop Relat Res. 2015; 473: 57-63
        • Werner B.C.
        • Evans C.L.
        • Carothers J.T.
        • Browne J.A.
        Primary total knee arthroplasty in super-obese patients: dramatically higher postoperative complication rates even compared to revision surgery.
        J Arthroplasty. 2015; 30: 849-853
        • Khuri S.F.
        • Daley J.
        • Henderson W.
        • Hur K.
        • Demakis J.
        • Aust J.B.
        • et al.
        The Department of Veterans Affairs’ NSQIP: the first national, validated, outcome-based, risk-adjusted, and peer-controlled program for the measurement and enhancement of the quality of surgical care. National VA Surgical Quality Improvement Program.
        Ann Surg. 1998; 228: 491-507
        • NSQIP
        American College of Surgeons National Surgical Quality Improvement Program.
        2015 ([accessed 1.01.17])
        • Baghoolizadeh M.
        • Schwarzkopf R.
        The Lawrence D. Dorr Surgical Techniques & Technologies Award: conversion total hip arthroplasty: is it a primary or revision hip arthroplasty.
        J Arthroplasty. 2016; 31: 16-21
        • Duchman K.R.
        • Gao Y.
        • Pugely A.J.
        • Martin C.T.
        • Noiseux N.O.
        • Callaghan J.J.
        The effect of smoking on short-term complications following total hip and knee arthroplasty.
        J Bone Joint Surg Am. 2015; 97: 1049-1058
        • Schairer W.W.
        • Lane J.M.
        • Halsey D.A.
        • Iorio R.
        • Padgett D.E.
        • McLawhorn A.S.
        The Frank Stinchfield Award: total hip arthroplasty for femoral neck fracture is not a typical DRG 470. A Propensity-matched Cohort Study.
        Clin Orthop Relat Res. 2017; 475: 353-360
        • R Core Team
        R: a language and environment for statistical computing.
        R Foundation for Statistical Computing, Vienna, Austria2015
        • Harrell Jr., F.E.
        rms: regression modeling strategies. R package version 4.4-0.
        2015 ([accessed 15.07.17])
        • George J.
        • Klika A.K.
        • Navale S.M.
        • Newman J.M.
        • Barsoum W.K.
        • Higuera C.A.
        Obesity epidemic: is its impact on total joint arthroplasty underestimated? An analysis of national trends.
        Clin Orthop Relat Res. 2017; 475: 1798-1806
        • George J.
        • Newman J.M.
        • Ramanathan D.
        • Klika A.K.
        • Higuera C.A.
        • Barsoum W.K.
        Administrative databases can yield false conclusions—an example of obesity in total joint arthroplasty.
        J Arthroplasty. 2017; 32: S86-S90
        • Shiloach M.
        • Frencher S.K.
        • Steeger J.E.
        • Rowell K.S.
        • Bartzokis K.
        • Tomeh M.G.
        • et al.
        Toward robust information: data quality and inter-rater reliability in the American College of Surgeons National Surgical Quality Improvement Program.
        J Am Coll Surg. 2010; 210: 6-16
        • Van Gent J.-M.
        • Zander A.L.
        • Olson E.J.
        • Shackford S.R.
        • Dunne C.E.
        • Sise C.B.
        • et al.
        Pulmonary embolism without deep venous thrombosis.
        J Trauma Acute Care Surg. 2014; 76: 1270-1274
        • Schwartz T.
        • Hingorani A.
        • Ascher E.
        • Marks N.
        • Shiferson A.
        • Jung D.
        • et al.
        Pulmonary embolism without deep venous thrombosis.
        Ann Vasc Surg. 2012; 26: 973-976
        • McCalden R.W.
        • Charron K.D.
        • MacDonald S.J.
        • Bourne R.B.
        • Naudie D.D.
        Does morbid obesity affect the outcome of total hip replacement?: an analysis of 3290 THRs.
        J Bone Joint Surg Br. 2011; 93: 321-325
        • Patel V.P.
        • Walsh M.
        • Sehgal B.
        • Preston C.
        • DeWal H.
        • Di Cesare P.E.
        Factors associated with prolonged wound drainage after primary total hip and knee arthroplasty.
        J Bone Joint Surg Am. 2007; 89: 33-38
        • Ward D.T.
        • Metz L.N.
        • Horst P.K.
        • Kim H.T.
        • Kuo A.C.
        Complications of morbid obesity in total joint arthroplasty: risk stratification based on BMI.
        J Arthroplasty. 2015; 30: 42-46
        • Memtsoudis S.G.
        • Besculides M.C.
        • Gaber L.
        • Liu S.
        • González Della Valle A.
        Risk factors for pulmonary embolism after hip and knee arthroplasty: a population-based study.
        Int Orthop. 2009; 33: 1739-1745
        • Nelson C.L.
        • Elkassabany N.M.
        • Kamath A.F.
        • Liu J.
        Low albumin levels, more than morbid obesity, are associated with complications after TKA.
        Clin Orthop Relat Res. 2015; 473: 3163-3172
        • Napier R.J.
        • O’Brien S.
        • Bennett D.
        • Doran E.
        • Sykes A.
        • Murray J.
        • et al.
        Intra-operative and short term outcome of total knee arthroplasty in morbidly obese patients.
        Knee. 2014; 21: 784-788
        • Walsh M.
        • Preston C.
        • Bong M.
        • Patel V.
        • Di Cesare P.E.
        Relative risk factors for requirement of blood transfusion after total hip arthroplasty.
        J Arthroplasty. 2007; 22: 1162-1167
        • Frisch N.
        • Wessell N.M.
        • Charters M.
        • Peterson E.
        • Cann B.
        • Greenstein A.
        • et al.
        Effect of body mass index on blood transfusion in total hip and knee arthroplasty.
        Orthopedics. 2016; 39: e844-e849
        • Thornqvist C.
        • Gislason G.H.
        • Køber L.
        • Jensen P.F.
        • Torp-Pedersen C.
        • Andersson C.
        Body mass index and risk of perioperative cardiovascular adverse events and mortality in 34,744 Danish patients undergoing hip or knee replacement.
        Acta Orthop. 2014; 85: 456-462
        • Watts C.D.
        • Houdek M.T.
        • Wagner E.R.
        • Taunton M.J.
        Subcutaneous fat thickness is associated with early reoperation and infection after total knee arthroplasty in morbidly obese patients.
        J Arthroplasty. 2016; 31: 1788-1791
        • Bourne R.
        • Mukhi S.
        • Zhu N.
        • Keresteci M.
        • Marin M.
        Role of obesity on the risk for total hip or knee arthroplasty.
        Clin Orthop Relat Res. 2007; 465: 185-188
        • Schrama J.C.
        • Espehaug B.
        • Hallan G.
        • Engesaeter L.B.
        • Furnes O.
        • Havelin L.I.
        • et al.
        Risk of revision for infection in primary total hip and knee arthroplasty in patients with rheumatoid arthritis compared with osteoarthritis: a prospective, population-based study on 108,786 hip and knee joint arthroplasties from the Norwegian Arthroplasty Register.
        Arthritis Care Res (Hoboken). 2010; 62: 473-479