Primary reverse shoulder arthroplasty in patients with metabolic syndrome is associated with increased rates of deep infection.

BACKGROUND: Metabolic syndrome (MetS) is an abnormal physiological condition that has been increasingly identified as a risk factor for complications after orthopedic surgery. Given the lack of information on the effect of MetS in shoulder arthroplasty (SA), this investigation analyzed the rates of postoperative complications and implant survivorship free from reoperation and revision in patients with and without MetS. METHODS: Between 2007 and 2017, data from 4635 adults who underwent a primary SA were collected and classified based on the presence or absence of MetS. MetS was defined as the existence of type 2 diabetes mellitus and a minimum of 2 of the following diagnoses: hyperlipidemia, hypertension, and body mass index ≥ 30 kg/m2 within 1 year of surgery. Of the 4635 arthroplasties, 714 were performed in patients with MetS (anatomic total shoulder arthroplasty [aTSA] in 289 and reverse shoulder arthroplasty [RSA] in 425) and 3921 were performed in patients without MetS (aTSA in 1736 and RSA in 2185). Demographic characteristics, complications, reoperations, and revision surgery were compared. RESULTS: At a mean of follow-up of 4.5 ± 2.3 years, 67 MetS patients (9.4%) and 343 non-MetS patients (8.7%) had sustained at least 1 postoperative complication (P = .851). Rotator cuff failure was the most common complication overall, with 84 cases (1.8%) (15 MetS cases [2.1%] and 69 non-MetS cases [1.8%], P = .851), and in both MetS and non-MetS patients, followed by infection, with 68 cases (1.2%) (10 MetS cases [1.4%] and 58 non-MetS cases [1.2%], P = .913). For aTSAs, the most common complication was rotator cuff failure (84 shoulders, 1.8%); for RSAs, the most common complication was periprosthetic fracture (52 shoulders, 1.1%). In RSAs, the rates of deep infection (1.9% vs. 0.7%, P = .04), instability (3.1% vs. 1.5%, P = .04), and deep venous thrombosis or pulmonary embolism (0.5% vs. 0.3%, P = .03) were found to be significantly higher in patients with MetS than in those without MetS. Reoperations were observed in 36 MetS patients (5%) and 170 non-MetS patients (4.3%) (P = .4). Revisions were performed in 30 MetS patients (4.2%) and 127 non-MetS patients (3.2%) (P = .19). The Kaplan-Meier 5-year rate of survivorship free from reoperation, revision, and prosthetic joint infection was equal between groups. CONCLUSIONS: A preoperative diagnosis of MetS in patients undergoing primary SA did not significantly increase the risk of postoperative complications, infection, reoperation, or revision following primary SA. However, in the RSA subgroup, complications were significantly more common in patients with MetS. Individual risk factors may be more appropriate than the umbrella diagnosis of MetS prior to aTSA.