Subscapularis ct-scan evaluation in patients with proximal humerus fracture: reverse total shoulder arthroplasty versus hemi-arthroplasty

Purpose: Hemiarthroplasty (HA) and Reverse Total Shoulder Arthroplasty (RTSA) are both reliable treatment options for complex proximal humerus fractures. While the role of the subscapularis tendon is well-defined in HA, its role in RTSA has not been clearly demonstrated. The purpose of our study is to evaluate the role of the subscapularis tendon in patients treated with HA and RTSA and investigate its association with clinical outcomes. Methods: Sixty-eight consecutive patients with proximal humeral fractures were prospectively enrolled in the study from June 2015 to May 2020 (RTSA= 36; HA=32). Shoulder CT scans were performed pre- and postoperatively, and subscapularis muscle cross-sectional area (SMCSA) and supraspinatus fossa cross-sectional area (SFCSA) were measured. SMCSA/SFCSA ratio was employed to standardize values. Patient-reported outcomes (PROs) and range of motion (ROM) were evaluated at the final follow-up. Results: RTSA group demonstrated higher PROs compared to HA patients: Constant Score (p= .0001), Quick Dash (p= .0006), Simple Shoulder Test (p= .01). Range of motion (ROM) was better in RTSA than HA: internal rotation (p= .0047 adduction and p= .026 abduction), external rotation (p= .001 adduction and p= .026 abduction) and forward flexion (p< .0001). Reduction of subscapularis size of >35% occurred in 20 RTSA and 8 HA (p = 0.01). The loss of subscapularis surface was greater in the RTSA patients (p=0.018). Conclusions: RTSA demonstrated better results compared to HA, providing better PROs and ROM. Postoperative reduction in subscapularis size was significantly higher in RTSA compared to HA. Subscapularis condition demonstrated no correlation with functional outcome in RTSA.