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HSS J. 2017 Feb;13(1):66-74. doi: 10.1007/s11420-016-9518-4. Epub 2016 Aug 16.

Hypoalbuminemia Is a Better Predictor than Obesity of Complications After Total Knee Arthroplasty: a Propensity Score-Adjusted Observational Analysis.

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Hospital for Special Surgery, Adult Reconstruction & Joint Replacement Division, 535 East 70th Street, New York, NY 10021 USA.



Obesity is an established risk factor for complications after total knee arthroplasty (TKA) and is often associated with malnutrition.


1. What is the prevalence of hypoalbuminemia in obese patients undergoing TKA? 2. What is the independent morbidity risk of malnutrition relative to obesity?


TKA cases were identified from the National Surgical Quality Improvement Program from 2005 to 2013. Propensity scores for having preoperative albumin measurements were calculated using demographics, BMI, and modified Charlson Comorbidity Index (CCI). Malnutrition was defined as hypoalbuminemia (<3.5 g/dL). Patients were classified by BMI as follows: non-obese (18.5-29.9), obese I (30-34.9), obese II (35-39.9), or obese III (≥40). Postoperative complications were compared across obesity and nutritional statuses. Multivariable propensity-adjusted logistic regressions were performed to determine associations between malnutrition, obesity, and 30-day outcomes.


There were 71,599 cases identified, with 34,800 (48.6%) having albumin measurements. Propensity score adjustment adequately accounted for selection bias, with adjusted p > 0.05 for observable characteristics. Malnutrition prevalence increased with BMI (6.1% in obese III vs. 3.7% in non-obese). With propensity-adjusted multivariable analysis, obese III was the only obesity class associated with any complication, wound complication, and reoperation. Hypoalbuminemia was a stronger and more consistent independent risk factor, for any complication, wound, cardiac, or respiratory complications, and death.


Hypoalbuminemia is a more consistent independent predictor of complications after TKA than obesity. Strategies for medical optimization of these conditions should be investigated.


hypoalbuminemia; malnutrition; total knee arthroplasty

[Available on 2018-02-01]

Conflict of interest statement

Michael C. Fu, MD, MHS and Alexander S. McLawhorn, MD, MBA have declared that they have no conflict of interest. Michael B. Cross, MD reports grants and personal fees from Smith and Nephew; personal fees from Link, Acelity, Exactech, Intellijoint; other from Journal of Orthopaedics and Traumatology and Bone Joint Journal 360; grants from Michael Price Family Foundation, outside the work. Douglas E. Padgett, MD reports personal fees from Stryker and Mako and other from Journal of Arthroplasty, outside the work. Human/Animal Rights All procedures followed were in accordance with the ethical standards of the responsible committee on human experimentation (institutional and national) and with the Helsinki Declaration of 1975, as revised in 2008 (5). Informed Consent Informed consent was waived from all patients for being included in the study. Required Author Forms Disclosure forms provided by the authors are available with the online version of this article.

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