Full-Polyethylene Glenosphere Reverse Shoulder Arthroplasty: Functional outcomes and notching rate at mid-term...

Introduction-Aim: Full-polyethylene glenosphere reverse shoulder arthroplasty (FP-RSA) known commonly as inverted-bearing concept utilizes a polyethylene glenosphere and metallic humeral liner. The aim was to assess mid-term outcomes of FP-RSA focusing on the incidence of scapular notching.

A retrospective analysis of 24 consecutive primary FP-RSA performed between 2017 and 2020 was conducted. At a minimum follow-up of 2 years, cases underwent clinical evaluation using Constant score (CS), Subjective Shoulder Value (SSV), American Shoulder and Elbow Score (ASES), pain assessment, range of motion (ROM) and radiological findings evaluating baseplate position, implant stability, and scapular notching.

At a mean follow-up of 3.2 ± 0.6 years, all clinical parameters showed significant improvement except external rotation (p < 0.05). Scapular notching rate was 20.83% all grade1 and 2. High glenoid position (p < 0.001) was significantly associated with scapular notching, which is correlated with lower CS (69 ± 16 vs. 51 ± 19; p = 0.049), SSV (80 ± 15vs. 67 ± 22; p = 0.026), ASES (85 ± 16 vs. 71 ± 21; p = 0.033), and anterior elevation (147◦ ± 24◦vs. 116◦ ± 38◦; p = 0.007). The use of a large glenosphere compared to small glenosphere was associated with better CS (79 ± 10vs. 65 ± 19; p = 0.006), external rotation (21 ± 11◦vs. 13 ± 9°; p = 0.036).

FP-RSA demonstrates favorable safety and efficacy at mid-term follow-up. Scapular notching, associated with high baseplate position, negatively impacts range of motion and clinical outcomes.