Metallic humeral and glenoid lateralized implants in reverse shoulder arthroplasty for cuff tear arthropathy and primary osteoarthritis

Background: Metallic humeral and glenoid lateralized implants have been developed to prevent common problems that can emerge using Grammont's concept (ie, medialization of center of rotation, decreased humeral offset, scapular notching) in reverse shoulder arthroplasty. The purpose of this study was to evaluate the clinical and radiological results of metallic humeral and glenoid lateralized implants for cuff tear arthropathy (CTA) and primary osteoarthritis (OA).

Methods: In this prospective study, patients with CTA or OA who underwent reverse shoulder arthroplasty using augmented base plates for glenoid lateralization and a "curved stem" design for the humeral side were included. The Constant-Murley score and Subjective Shoulder Value were documented at 1- and 2-year follow-ups. Radiographs were reviewed for scapular notching, instability, loosening, osteolysis, ossification, bone resorption, or fractures. Lateralization and distalization shoulder angles were evaluated at the final follow-up.

Results: There were 23 patients with CTA and 19 patients with OA (27 women; mean age, 76 years; range, 59-85) available for examination at 2 years. Both groups increased significantly in all outcome measures compared with baseline (P < .01). Although patients with OA generally had lower baseline scores, the outcome scores were similar and did not show any statistically significant differences. The mean Constant-Murley score and Subjective Shoulder Value at the final follow-up were 78 points (standard deviation [SD] 10) and 84% (SD 11) for patients with CTA, respectively, and corresponding values were 80 points (SD 16) and 92% (SD 12) for the OA group. No scapular notching was observed. The mean value of the lateralization shoulder angle was 81.5° (SD 9.7) and for the distalization shoulder angle was 54.8° (SD 9.4). Neither scapular spine fractures nor instability was observed in this patient cohort.

Conclusion: Metallic humeral and glenoid lateralization achieves excellent clinical results in terms of shoulder function, pain relief, muscle strength, and patient-reported subjective assessment without instability or radiographic signs of scapular notching. Patients with primary OA showed an overall trend toward better clinical improvement than patients with CTA.