SMR TT Augmented 360 baseplates: how do they compare to standard baseplates in reverse shoulder arthroplasty? Minimum 2 years' clinical and radiographic follow-up

Abstract

Background: Reverse total shoulder arthroplasty (rTSA) is a popular surgical option for end-stage arthritis, rotator cuff arthropathy, or proximal humerus fractures. The treatment of patients with glenoid bone loss and deformity, however, remains challenging. Modern implant systems now have the option of wedge-shaped augmented baseplates to supplement deficient glenoid bone and omit the need for excessive glenoid reaming or the use of bone graft. This study set out to determine if the new augmented baseplates were clinically and radiologically comparable to standard baseplates.

Methods: A retrospective review of prospectively collected data was conducted on all patients who received the SMR TT Augmented 360 baseplate (Lima Corporate) between January 2020 and March 2022. All data were collected as part of the hospital prospective database from which a comparative sample of patients who received a standard baseplate was obtained. The minimum follow-up period was 2 years. Preoperative clinical information was recorded using pain score (1-5), Oxford Shoulder Score (OSS), American Shoulder and Elbow Surgeons Standardized Shoulder Assessment Form (ASES) score, and range of motion. The same clinical scores were collected at 2-year follow-up with radiologic assessments.

Results: A total of 104 patients were included in this study, with 52 in the augmented baseplate group and 52 in the standard baseplate group. At the minimum 2-year follow-up, there were no statistically significant differences between the 2 groups in OSS, pain score, or range of motion at 2 years. Postoperative ASES scores were 73 ± 22 in the augmented baseplate group and 82 ± 15 in the standard baseplate group; this difference was statistically, but not clinically, significant. There was a statistically significant difference in the size of overhang, with the augmented baseplate group having a mean glenoid overhang of 5.0 ± 1.9 mm and the standard baseplate group a mean of 6.5 ± 1.8 mm. There was no other statistically or clinically significant difference in any other radiologic outcome.

Discussion: In both groups, it was possible to achieve a well-fixed stable rTSA with improved functional and radiologic outcomes at the 2-year follow-up. Augmented baseplates were not clinically inferior to standard baseplates across any measure. This study demonstrates that augmented baseplates appear to be a safe alternative to other techniques such as eccentric reaming or bony increased-offset rTSA with reliable patient outcomes.

Keywords: Reverse shoulder arthroplasty; augment; baseplate; bone loss; glenoid; outcome.