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Objectives and questions: Complications associated with the classical Grammont design for reverse shoulder arthroplasty include scapular notching, instability and dislocation, infection, and acromial or scapular spine fractures. With advances in implant design and the introduction of lateralization strategies, the complication profile appears to have shifted. The aim of this study was a prospective longitudinal analysis of intraoperative and postoperative complications following reverse shoulder arthroplasty using a metaphyseal short stem with bipolar metallic lateralization.

Material and methods: From April 2022 to July 2025, patients were enrolled and followed for one year. Indications included primary and secondary glenohumeral osteoarthritis, cuff tear arthropathy, and revision surgery. Glenoid lateralization was achieved using metallic full-wedge or half-wedge baseplates, with 3- or 6-mm lateralization. Symmetric or asymmetric humeral inlays were used, resulting in neck–shaft angles of 135° or 145°. Intraoperative and postoperative complications were recorded from surgical reports, clinical documentation, and available radiographs. Exploratory logistic regression analysis was performed with complications as the dependent variable and age, ASA classification, and surgery duration as independent variables.

Results: Postoperative follow-up was available for 269 patients at six months and for 184 patients at twelve months. Most common indication was cuff tear arthropathy (54.7%). The intraoperative complication rate was 1.4% and included three greater tuberosity fractures and one vascular injury. These were addressed intraoperatively with no clinical sequelae. At six months postoperatively, the complication rate was 7.1% (19/269). Most frequent complications were acromial spine fractures (2.6%), neurological complications (1.9%), and scapular notching (1.1%). Surgical revision was required for one acromial spine fracture, one infection, and one postoperative hematoma. Between six and twelve months postoperatively, six complications occurred, including two atraumatic acromial spine fractures (1.1%), one scapular body fracture (0.5%), one late-onset infection (0.5%), one humeral component shift (0.5%), and one additional case of scapular notching (0.5%). The late-onset infection required revision surgery.Overall, 3.8% of patients (7/184) required revision surgery within one year. No cases of instability were observed in the entire cohort. Exploratory logistic regression analysis revealed no independent associations between analyzed parameters and complications.

Discussion and conclusions: Reverse shoulder arthroplasty using bipolar metallic lateralization with a metaphyseal-anchored short stem demonstrates a low rate of complications requiring revision surgery. Compared with the classic Grammont design, the complication profile appears to have shifted toward the absence of instability events and reduced scapular notching, while maintaining a moderate fracture rate. Longer follow-up is required to assess mid- to long-term complications.