Postoperative Reverse Shoulder Arthroplasty Angle Is Not Correlated with Patient-Reported Outcomes or Range of Motion

To determine whether postoperative reverse shoulder arthroplasty (RSA) angle as a continuous variable is correlated with postoperative patient-reported outcome measures (PROMs) or range of motion (ROM) for patients undergoing RSA with modern implants.

A retrospective review was performed to measure preoperative and postoperative RSA angle using radiographs for patients with a minimum 2-year follow-up undergoing primary RSA at a single academic center between 2015 and 2022. PROMs including American Shoulder and Elbow Surgeon (ASES), visual analog scale (VAS), and Single Assessment Numeric Evaluation (SANE) scores were collected. External rotation, internal rotation, and forward flexion ROM measurements were also recorded. Pearson and Spearman correlation analyses were performed to determine whether there were any linear or monotonic relationships between postoperative RSA angle and the other variables.

A total of 142 patients were included with an average follow-up of 3.3 ± 1.3 years. The average RSA angle was 19.3° ± 9.1° preoperatively and 4.3° ± 7.1° postoperatively. No significant relationship between postoperative RSA angle and PROMs was found: ASES (r = -0.01, P = .87), VAS (r = 0.01, P = .85), and SANE (r = 0.04, P = .67). Patients showed varying degrees of improvement in PROMs, as indicated by rates of achieving the minimal clinically important difference: ASES: 77.3%; VAS: 92.0%; SANE: 66.7%. Final ROM also showed no statistically significant association with postoperative RSA angle: external rotation (r = 0.05, P = .59), internal rotation (r = 0.03, P = .74), and forward flexion (r = -0.08, P = .59). Patients with a higher postoperative RSA angle had a higher preoperative RSA angle (P < .001).

Postoperative RSA angle was not correlated with differences in postoperative PROMs, including ASES, VAS, and SANE, or with differences in postoperative ROM. Inclination of postoperative RSA angle, particularly without significant outliers, may not be detrimental to patient outcomes.

Level IV, retrospective therapeutic case series.