Comparison of short-term clinical outcomes and radiographic changes in Grammont reverse shoulder arthroplasty between the French and Japanese populations: A propensity score-matched analysis.

Background: Although Grammont-style reverse total shoulder arthroplasty (RSA) showed excellent clinical results in Europe, its utility for Asian populations remains unclear. This study aimed to compare the French and Japanese populations in terms of range of motion (ROM), functional outcomes, and scapular notching rates in patients who underwent standard Grammont-style RSA. We hypothesized that RSA for the Japanese population may not provide as good ROM and functional results at the final follow-up as that for the French population.
Methods: A total of 25 Japanese patients undergoing RSA were propensity score matched to 25 French patients undergoing RSA. The patients were matched for four different covariates using a propensity score analysis. The minimum follow-up period was 2 years. We investigated differences between the populations with respect to body size and shoulder joint ROM and Constant score (CS) measured preoperatively and at the final follow-up. Scapular notching was examined using radiographs at the final follow-up.
Results: The average height and weight of the French and Japanese patients were 164 cm and 70 kg and 152 cm and 56 kg, respectively. Anterior elevation (AE), external rotation (ER) at the side, internal rotation (IR), and CS total changed from 101° to 145°, 17° to 15°, 4.5 points to 5.5 points, and 36 points to 72 points, respectively, in the French population and from 63° to 119°, 8.5° to 13°, 4.6 points to 4 points, and 28 points to 58 points, respectively, in the Japanese population. AE improved in both the groups; ER and IR remained unchanged before and after surgery. The frequency of scapular notching (>grade 1) was higher in the Japanese population (56%) than in the French population (20%) (p = 0.019).
Conclusions: Grammont-style RSA improved AE and CS in both the populations, but AE and CS were significantly higher in the French population than in the Japanese population at the final follow-up. Scapular notching frequently occurs in the Japanese population.
(Copyright © 2022 The Japanese Orthopaedic Association. Published by Elsevier B.V. All rights reserved.)