Does Morbid Obesity (BMI ≥40 kg/m2) Impact Operative Time, Blood Loss, Length of Stay, or Complications Following Anatomic Total Shoulder Arthroplasty?

There have been conflicting reports regarding the effects of obesity on both surgical time and blood loss following anatomic shoulder arthroplasty. Varying categories of obesity has made comparison amongst existing studies difficult. A retrospective review of consecutive anatomic shoulder arthroplasty cases (aTSA) was undertaken. Demographic data, including age, gender, body mass index (BMI), age-adjusted Charleson Comorbidity Index (ACCI), operative time, hospital length of stay (LOS), and both POD#1 and discharge visual analogue score (VAS) was collected. Intra-operative total blood volume loss (ITBVL) and need for transfusion was calculated. BMI was categorized as non-obese (<30 kg/m2), obese (30-40 kg/m2) and morbidly obese (≥40 kg/m2). Unadjusted associations of BMI with operative time, ITBVL and LOS were examined using Spearman correlation coefficients. Regression analysis was used to identify factors associated with hospital LOS. There were 130 aTSA cases performed, including 45 short stem and 85 stemless implants, of which 23 (17.7%) were morbidly obese, 60 (46.2%) were obese and 47 (36.1%) were non-obese. Median operative time for the morbidly obese cohort was 119.5 minutes (IQR 93.0, 142.0) versus 116.5 minutes (IQR 99.5, 134.5) for the obese cohort versus 125.0 minutes (IQR, 99.0, 146.0) for the non-obese cohort. (P=0.61) The median ITBVL for the morbidly obese cohort was 235.8 ml (IQR 144.3, 329.7) versus 220.1 ml (IQR 147.7, 262.7) for the obese cohort versus 216.3 ml (IQR 139.7, 315.5) for the non-obese cohort. (P=0.72). BMI ≥40kg/m2 (IRR 1.32, P=0.038), age (IRR 1.01, P=0.026), and female gender (IRR 1.54, P<0.001) were predictive of increased LOS. There was no difference with regards to in-hospital medical complications (P=0.13), surgical complications (P=1.0), need for re-operation (P=0.66) and 30-day return to the ER (P=0.06). Morbid obesity was not associated with increased surgical time, ITBVL and perioperative medical or surgical complications following aTSA, though it was predictive of increased hospital LOS. Level of evidence: III