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Comparison of Postoperative Outcomes Following Simultaneous Versus Staged Bilateral Total Knee Arthroplasty in Obese
Dev Patel1, Samuel Gay2, Eric Belzile3
1Faculty of Medicine and Health Sciences, McGill University, Montreal, Quebec, Canada.
Background:
Obesity is associated with higher complication risk after total knee arthroplasty (TKA), and evidence comparing simultaneous versus staged bilateral TKA (BTKA) across obesity severity is limited.
Methods:
Adults undergoing BTKA (2014 to 2024) were identified from a global deidentified research network. Patients were classified by surgical timing (simultaneous; short-interval staged [one to less than four months]; longer-interval staged [four to 12 months]), and body mass index (BMI) (nonobese [less than 30]; obesity classes 1 [30 to less than 35]; 2 [35 to less than 40]; and 3 [greater than 40]). Both 30-day and two-year outcomes were evaluated using logistic and linear regressions adjusted for age, sex, ethnicity, and Charlson comorbidity score, with BMI-by-timing interaction testing.
Results:
Among 11,965 patients (5,653 nonobese; 3,096 class 1; 1,870 class 2; 1,346 class 3), BMI category modified surgical timing's association with 30-day composite complications (P < 0.001), readmission (P = 0.017), two-year aseptic loosening (P = 0.011), all-cause revision (P = 0.011), and lengths of stay (LOS) (P < 0.001). Staged BTKA showed lower odds of composite complications, largest in class 3 (short-interval [odds ratio (OR), 0.18; 95% confidence interval (CI): 0.09 to 0.35]). It also showed lower odds of aseptic loosening and revision in classes 2 and 3, largest in class 3 (aseptic loosening [OR, 0.24; 95% CI: 0.08 to 0.71]; revision [OR, 0.13; 95% CI: 0.04 to 0.42]). In nonobese patients, staged BTKA conversely showed higher 30-day readmission ([OR, 1.93; 95% CI: 1.17 to 3.17]). Effects were comparable for the longer interval. The LOS was longer after simultaneous than staged BTKA, decreasing at higher BMI.
Conclusions:
The BMI category modified surgical timing's association with postoperative outcomes. Staged BTKA reduced 30-day composite complications from class 1 onward and two-year aseptic loosening and all-cause revision at BMI ≥ 35. The largest reductions occured in class 3.
Level Of Evidence:
III.