2025 ISAKOS Biennial Congress Paper
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 Pre-operative Planning Software: A Retrospective Cohort Study
Pietro Gregori, MD, Roma, Lazio ITALY
Edoardo Franceschetti, MD, Roma, Rome ITALY
Giancarlo Giurazza, MD, rome ITALY
Alice Laudisio, MD, Roma ITALY
Giovanni Perricone, MD, Rome, Rome ITALY
Umile Giuseppe Longo, MD, MSc, PhD, Prof., Rome ITALY
Rocco Papalia, MD, PhD, Prof., Rome ITALY
Fondazione Policlinico Universitario Campus bio-Medico di Roma, Rome, Rome, ITALY
FDA Status Not Applicable
Summary
Humeral Distal filling ratio in Shoulder artrhoplasty Influences Stress shielding and clinical outcomes
Abstract
Introduction
The link between implant features and radiological complications as well as their relation to clinical outcomes in Reverse shoulder arthroplasty is debated. The aim of the study was to assess if 3D CT-scan based measurement 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 exists.
Methods
50 patients with short-stem RTSAs, preoperative CT scans, and a minimum 24-month radiographic follow-up were included in the study. The postoperative filling ratios were measured on plain radiographs, while the 3D DFRs of the metaphyseal segments were measured using Glenosys Sistem (Wright). At 24 months follow-up all patients were evaluated by assessing the Simple shoulder Test, Constant-Murley Score and Visual Analogue Scale.
Results
our results indicate a correlation between the 3D DFR and the development of radiographic signs of SS (Rs 0.54; P 0.001), and between postoperative DFR and SS (Rs 0.71; P<0.001). Furthermore, the 3D DFR and the postoperative DFR were correlated (Rs 0.89; P<.0001). Among the collected data, we found out that SS negatively affects the postoperative mobility, decreasing the anterior elevation of the shoulder.
Conclusions
The preoperative planning based on 3D CT and thus the calculation of DFR, is a good predictor of humeral stress shielding after short-stem RTSA. The presence of Stress shielding decreases clinical outcomes by lowering the anterior elevation of the shoulder.