Complications in total shoulder and reverse total shoulder arthroplasty by body mass index.

Introduction: The purpose of this study was to identify the effects of body mass index (BMI) on long-term outcomes (revision rate, 1-year mortality rate, 3-year surgical site infection rate, and 90-day inpatient all-cause readmission rate) after total shoulder arthroplasty (TSA) and reverse TSA (RTSA).

Methods: A large shoulder arthroplasty registry was used to review outcomes after TSA and RTSA. The registry monitors patient's revision, mortality, infection, and readmission rates. The exposure of interest was the patient's BMI at the time of the surgery, which was stratified by 5 kg/m increments.

Results: Selected for this study were 4630 patients who underwent TSA and RTSA between 2007 and 2013, of which 3483 (75.2%) were TSA and 1147 (24.8%) were RTSA. The overall combined (TSA and RTSA) revision rate was 1.7%. After adjusting for confounders in the overall models (TSA and RTSA combined), higher BMI was not associated with higher risk of aseptic revision, 1-year mortality, or 3-year deep infection. In TSA-specific models, every 5 kg/m increase in BMI was marginally associated with a 16% increase in the likelihood of 90-day readmission. This association was not observed in the RTSA model. In RTSA-specific models, every 5 kg/m increase in BMI was marginally associated with higher risk of 3-year deep infection. This association was not observed in the TSA model.

Conclusion: Shoulder arthroplasty in obese patients is not associated with higher risk of aseptic revision. The BMI has different effects on TSA and RSA. The surgeon should anticipate increased risk of readmission after TSA and infection after RSA.