Poster 155: An Ultrasound and Clinical Evaluation in Patients Following Treatment for Proximal Humerus Fractures: Reverse Versus Anatomical Total Shoulder Arthroplasty

Abstract

Objectives: Anatomic Total Shoulder Arthroplasty (ATSA) and Reverse Total Shoulder Arthroplasty (RTSA) are both viable treatment options for complex proximal humerus fractures. With its principal role as an abductor and internal rotator in a native joint, the subscapularis potentially plays an important functional and stability role postoperatively. Although less studied in RTSA, studies have found that failure of subscapularis repair is associated with anterior instability, and decreased range of motion (ROM), strength, and outcome scores following ATSA. The purpose of our study is to evaluate and compare the postoperative clinical, radiographic, and patient-reported outcomes following subscapularis reattachment in patients treated with either ATSA or RTSA. Methods: Sixty-eight consecutive patients with proximal humeral fractures were prospectively enrolled in the study between June 2015 and May 2020 (RTSA = 40; TSA = 28). Ultrasound scans of the subscapularis were performed postoperatively, and the subscapularis muscle cross-sectional area (iSMCSA) and contralateral subscapularis muscle cross-sectional area (cSMCSA) were measured. The ratio of the 2 values (iSMCSA/cSFCSA) was utilized to standardize values. Patient-reported outcomes (PROs) and ROM were evaluated at the final follow-up. Results: Demographically, there was no significant difference between age, arm dominance, surgical laterality, diabetes, or hypertension between the patient groups (Table 1). The RTSA group demonstrated higher PROs compared to TSA patients: Constant Score (p = .0007), Quick Dash (p = .0005), and ASES score (p = .09). ROM was better in the RTSA cohort, with statically significant values with internal rotation (p = .022 abduction), external rotation (p = .02 adduction and p = .01 abduction), abduction (p = 0.02), and forward flexion (p = .003). Radiographic ultrasound findings illustrated greater reduction in size of the subscapularis in the TSA cohort when compared to the contralateral, nonoperative subscapularis (40% vs 27%; p = 0.002). Reduction of subscapularis size of >35% occurred in 2 RTSA (7%) and 8 TSA patients (44%) (p = 0.01) (Table 2). Conclusions: Subscapularis repair following RTSA demonstrated better results compared to subscapularis repair following TSA, providing better PROs and ROM. Subscapularis muscle tissue decreased 50% more in the ATSA versus RTSA patients (40% vs 27%). Subscapularis condition demonstrated no correlation with functional outcome in RTSA.