Outcomes and Costs of Reverse Shoulder Arthroplasty in the Morbidly Obese: A Case Control Study

The rising number of morbidly obese patients has important consequences for the health-care system. We investigated the effect of morbid obesity on outcomes, complications, discharge disposition, and costs in patients undergoing reverse shoulder arthroplasty.

Our joint registry was searched for all patients who had undergone primary reverse shoulder arthroplasty for a reason other than fracture from 2003 to 2010 and had a minimum of twenty-four months of follow-up. Twenty-one patients with a body mass index (BMI) of ≥40 kg/m² were identified (follow-up, 45 ± 16 months; sex, seventeen female and four male; age, 69 ± 7 years) and were compared with sixty-three matched control patients with a BMI of <30 kg/m² (follow-up, 48 ± 20 months; sex, fifty female and thirteen male; age, 71 ± 6 years) after an a priori sample size calculation. Outcome instrument data were obtained preoperatively and postoperatively. The Charlson-Deyo comorbidity index (CDI) score, total comorbidities, operative time, blood loss, duration of hospital stay, discharge disposition, costs, and complications were recorded.

Compared with nonobese patients, morbidly obese patients had similar improvements in functional outcomes (e.g., American Shoulder and Elbow Surgeons score, 32 to 69 compared with 40 to 78) and in shoulder motion (e.g., forward flexion, 61° to 140° compared with 74° to 153°); all improvements were significant (p < 0.05). Morbidly obese patients had a similar rate of scapular notching (odds ratio [OR] = 0.58, p = 0.63), more total comorbidities excluding obesity (six compared with four, p = 0.001), a higher CDI (2 compared with 1, p = 0.025), and a higher rate of obstructive sleep apnea (OR = 27.7, p = 0.0001). Their operative time was thirteen minutes longer (p = 0.014) and their blood loss was 40 mL greater (p = 0.008). Morbidly obese patients had a similar duration of stay (3.1 compared with 2.6 days, p = 0.823) and hospital readmission rate (OR = 16.3, p = 0.08) but a sixfold higher rate of discharge to rehabilitation facilities rather than to home (OR = 8, p < 0.0001). Hospital costs were higher by $2974 (p = 0.009). The rates of major complications (n = 4 compared with 8, p = 0.479) and of minor complications (n = 3 compared with 14, p = 0.440) were similar. No intraoperative complications or mechanical device failures were noted in either group.

Reverse shoulder arthroplasty appears to be as safe and effective in morbidly obese patients, although it has an increased cost and patients have a lower rate of discharge to home and greater care needs after discharge.

Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.