Morbid Obesity in Revision Total Knee Arthroplasty: A Significant Risk Factor for Re-Operation

Background: The purpose of this study is to compare surgical and clinical outcomes between matched groups of morbidly obese (body mass index [BMI] > 40 kg/m(2)) and non-morbidly obese (BMI < 40 kg/m(2)) patients undergoing first-time revision total knee arthroplasty with a minimum 5-year follow-up. Methods: Two groups of 87 patients (BMI > 40 or < 40 kg/m(2)) were matched 1: 1 based on age at the time of revision, gender, and diagnosis for revision (aseptic or septic causes). Results: The morbidly obese group had a significantly greater incidence of re-operation (34.5% [30/87] vs 16.1% [14/87], P =.005) and re-revision (27.6% [24/87] vs 12.6% [11/87], P =.014) with a significantly lower 10-year survivorship for re-operation (P =.05) and subsequent revision (P =.014). In particular, the aseptic sub-group had a greater incidence of re-operation (29.9% [20/67] vs 13.4% [9/67], P =.021) and rerevision (26.9% [18/67] vs 11.9% [8/67], P =.029). The non-morbidly obese group demonstrated higher final Western Ontario and McMaster Universities Index scores (63.1 +/- 19.5 vs 55.5 +/- 22.5, P =.030) and a greater change between pre-operative and final KSS (45.6 +/- 44.3 vs 39.7 +/- 48.4, P =.040) and SF-12 Mental component (3.6 +/- 10.8 vs -1.4 +/- 10.3, P =.013). Conclusion: Morbidly obese patients undergoing revision total knee arthroplasty have a greater risk of re-operation and re-revision while experiencing lower clinical outcome scores compared to nonmorbidly obese patients. These patients should be informed of the higher potential for re-operation and the possibility of poor results. (c) 2019 Elsevier Inc. All rights reserved.