Background

The SWIFT trial is a multi-site, prospective trial comparing knee physical function outcomes in total knee arthroplasty (TKA) candidates with severe obesity who undergo bariatric surgery prior to TKA versus TKA only. This preliminary analysis evaluates changes in knee function for patients who underwent bariatric surgery.

Methods

Patients with bariatric surgery and > 6 months postoperative follow up were evaluated for changes in outcomes including TKA deferral, improvement in Knee Injury and Osteoarthritis Outcome Score (KOOS, 10-point increase), and improvement in Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC, 16% reduction). Multiple logistic regression was used to assess the association of patient characteristics with knee outcomes.

Results

Of 66 bariatric surgery patients, 46 (23 RYGB; 23LSG) completed surgery with adequate follow up; age 53+-10; BMI 46+-8; female 83%. Comorbidity: 54% OSA; 41% diabetes; 67% hypertension. 51% of patients deferred TKA because of knee improvement; 68% and 64% achieved improvement in KOOS and WOMAC, respectively. In multiple regression, surgery type, age, and gender were not associated with knee outcomes. Lower pre-surgery BMI was associated with greater TKA deferral (p=0.0052), greater KOOS improvement (p=0.018), and greater WOMAC improvement (p=0.038). Higher comorbidity burden was associated with reduced likelihood of TKA deferral (p=0.012), and lower chance of both improved KOOS and WOMAC (p=0.05 and P0.010 respectively).

Conclusions

Bariatric surgery in patients eligible for TKA leads to improved knee function and short-term avoidance of TKA with optimization of outcomes associated with lower BMI and reduced disease burden