Risk factors associated with pain while sleeping on the affected shoulder after primary reverse shoulder arthroplasty.

Background: The purpose of this study was to identify risk factors of pain while lying on the operative shoulder following primary reverse total shoulder arthroplasty (rTSA).

Methods: Patients who underwent primary rTSA with available (1-year) follow-up data were retrospectively identified. Demographics, diagnosis, comorbidities, implant configuration, surgical information, and pain scores (including preoperative, postoperative and improvement in pain) were assessed while lying on the operated shoulder. To categorize preoperative pain while lying on the operative shoulder, cohorts were defined based on above or below the average pain level. Postoperative pain and improvement in pain were defined based on the following thresholds: patient acceptable symptomatic state (PASS), minimal clinically important difference (MCID), and substantial clinical benefit (SCB). The PASS was defined as the 75th percentile of pain scores in patients with high satisfaction ratings after rTSA, while MCID and SCB were calculated as the difference in average pain improvement in patients with high versus low satisfaction rates postoperatively. Univariate and multivariate logistic regression analyses were conducted.

Results: A total of 4,235 patients who underwent rTSA were included. Previous shoulder surgery, tobacco use, and preoperative pain lying on the operative shoulder failed to achieve threshold values. Subscapularis repair was associated with an improved ability to achieve the thresholds.

Conclusions: Tobacco use, higher preoperative pain levels, and previous shoulder surgery were negatively associated with satisfactory improvement in pain while lying on the postoperative shoulder. In contrast, subscapularis repair was associated with clinically significant improvements. Given that postoperative pain when lying on the operative side is a frequent preoperative question, understanding these influencing factors is useful when counseling patients on postoperative expectations. Level of evidence: III.