Stress shielding influences shoulder function after reverse shoulder arthroplasty using a short stem at minimum 2 years follow-up and can be predicted using a preoperative planning software: A retrospective cohort study.

Franceschetti, Edoardo; Gregori, Pietro; Laudisio, Alice; De Andreis, Chiara; Perricone, Giovanni; Giurazza, Giancarlo; Paciotti, Michele; Longo, Umile Giuseppe et al. · Shoulder Elbow · 2025

retrospective_cohort · Level III

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Abstract

The aim of the study was to assess if 3D CT-scan-based planification of distal filling ratio (DFR) is accurate when compared to postoperative DFR calculated on plain X-rays. A secondary aim was to investigate if an association between clinical outcomes and the degree of stress shielding (SS) exists. Fifty patients with short-stem reverse shoulder arthroplasties, preoperative CT scans, and a minimum 24-month radiographic follow-up were included in the study. At 24 months follow-up, all patients were evaluated by assessing the postoperative filling ratios, the 3D DFRs, the simple shoulder test, Constant-Murley score, and visual analogue scale through a prospectively data collection and statistically analyzed. A correlation between the 3D DFR and SS onset (r<sub>s</sub> 0.54; <i>P</i> < 0.001), and between postoperative DFR and SS (r<sub>s</sub> 0.71; <i>P</i> < 0.001), was found. The 3D DFR and the postoperative DFR were correlated (r<sub>s</sub> 0.89; <i>P</i> < 0.0001). SS negatively affects the postoperative range of motion, decreasing the forward elevation of the shoulder. The calculation of DFR based on 3D CT planning is a good predictor of humeral SS after short-stem RTAs. The presence of SS decreases clinical outcomes by lowering the anterior elevation of the shoulder. Case series.

Anatomy