Clinical and Radiological Results of Reverse Total Shoulder Arthroplasty Using a 25-mm Glenoid Baseplate

Background: The size of the baseplate used in reverse total shoulder arthroplasty (RTSA) tends to be larger than the average size of the glenoid in the Korean population. The mismatch between the sizes of the baseplate and the patient's glenoid may result in improper fixation of the glenoid baseplate. This in turn may lead to the premature loosening of the glenoid component. Thus, we evaluated the short-term results of using a 25-mm baseplate in RTSA. Methods: Seventeen patients with cuff tear arthropathy underwent RTSA with a 25-mm baseplate. The mean age of the patients was 70.1 years, and the mean follow-up period was 14.0 months. We evaluated clinical outcomes preoperatively and postoperatively: the range of shoulder motion, the American Shoulder and Elbow Surgeons (ASES) score, and the Korean Shoulder Society (KSS) score. Results: We found that the mean ASES score and KSS improved from 35.0 to 74.4 (p<0.001) and from 46.9 to 71.8 (p<0.001) with RTSA. The mean forward elevation and abduction, external rotation also improved from $78.6^{\circ}$ to $134.3^{\circ}$ (p<0.05) and from $66.6^{\circ}$ to $125.0^{\circ}$ (p<0.05), from $20.2^{\circ}$ to $28.4^{\circ}$ (p=0.43). Postoperative complications were seen in 12% of patients, but neither the loosening of the glenoid baseplate nor inferior scapular notching were observed. Conclusions: In sum, the results of using a 25-mm baseplate in RTSA were similar to those of previous reports. Even though the outcomes are those of a short-term follow-up, neither the loosening of the glenoid baseplate nor the scapular notching were observed.