Factors that increase the rate of periprosthetic dislocation after reverse shoulder arthroplasty.

Introduction: Reverse shoulder arthroplasty (RSA) is considered one of the greatest technological innovations in shoulder reconstruction surgery, as evidenced by the fact its growth rate of usage is greatest among all shoulder arthroplasties. However, like all arthroplasties, a post-surgical complication often arises. One of these complications, periprosthetic dislocation (PPD), requires revision and poses, therefore, a burden on both patients and healthcare providers. While PPD is understood to be a complication of RSA, it is unclear to what extent certain risk factors and co-morbidities predispose patients to post-RSA PPD. The purpose of this study was to identify and evaluate the impact of specific risk factors and co-morbidities that contribute to the development of PPD following RSA.

Methods: In this retrospective study, we used the Nationwide Inpatient Sample (NIS) database from 2016-2019 to analyze the prevalence and impact of various risk factors and co-morbidities on the incidence of PPD following RSA. A univariate and subsequent multivariate logistic regression model was made to provide a descriptive association between variables that impact the rates of PPD after RSA.

Results: The NIS database identified 59,925 patients, 1,000 of whom experienced a PPD while the remaining 58,825 were placed in the non-PPD group (controls). The PPD group consisted predominantly of females (53.10%) and Caucasians (86.30%). There was a higher incidence of tobacco-related disorders (P = 0.003), obesity (P < 0.001), morbid obesity (P < 0.001), liver cirrhosis (P < 0.001), and Parkinson's disease (PD) (P < 0.001) in PPD patients compared to controls. Young patients had a 1.89-fold increased odds (OR: 1.89, 95% CI [1.58, 2.26], P < 0.001), patients with tobacco-related disorders had decreased odds (OR: 0.80, 95% CI [0.67, 0.97], P = 0.02), morbidly obese patients had 1.50 times the odds (OR: 1.50, 95% CI [1.14, 1.97]), liver cirrhosis patients had 2.67-fold increased odds (OR: 2.67, 95% CI [1.55, 4.60], P < 0.001), and Parkinson's disease patients had 2.66 times the odds (OR: 2.66, 95% CI [1.78, 3.96], P < 0.001) to develop PPD following RSA compared to patients who did not have the corresponding condition.

Conclusions: Patients with specific risk factors and co-morbidities are predisposed to developing PPD after RSA. Risk factors that were found to be associated with a higher incidence of PPD are gender (female), race (Caucasian), and age (young patients). Analysis revealed the history of tobacco-related disorder, obesity, morbid obesity, liver cirrhosis, and Parkinson's disease increased the odds of developing PPD following RSA. These findings can inform both healthcare providers and patients to improve RSA surgical outcomes and tailor post-surgery recovery programs to fit the patient's needs.