Higher modified frailty index score is associated with 30-day postoperative complications following simultaneous bilateral total knee arthroplasty.

Background: There is no clear consensus regarding patient populations at highest risk for complications from simultaneous bilateral total knee arthroplasty (TKA). The purpose of this study was to determine whether the comorbidities comprising the modified Frailty Index (mFI) were correlated with poor outcomes following simultaneous bilateral TKA.

Methods: From 2006 to 2019, patients undergoing bilateral TKA aged 50 years or older were identified in a national database. The 5-item mFI was calculated based on the presence of five comorbidities: diabetes, congestive heart failure, hypertension, chronic obstructive pulmonary disease, and dependent functional status. Chi-squared and multivariable regression analyses were used to evaluate the association of mFI scores with postoperative complications.

Results: The study analyzed 8,776 patients with an average age of 65 years. After adjustment on multivariable regression analysis, compared to patients with a mFI score of 0, those with a score of 1 had an increased risk of pulmonary complication (OR 3.14; p = 0.011), renal problem (OR 12.86; p = 0.022), sepsis complication (OR 2.82; p = 0.024), postoperative transfusion (OR 1.19; p = 0.012), and non-home discharge (OR 1.17; p = 0.002).Patients with a score of 2 compared to 0 had similar complications when compared. These patients had an increased risk of cardiac complication (OR 4.84; p = 0.009) and prolonged hospital stay (OR 4.06; p < 0.001).

Conclusion: Increased mFI scores were associated with significantly higher complication rates in patients undergoing simultaneous bilateral TKA compared to unilateral TKA. Our results can be used to identify which patients may need a staged bilateral TKA or preoperative optimization to safely undergo a simultaneous bilateral TKA.

Level Of Evidence: III.