How to success stemless reverse shoulder arthroplasty by focusing on humerus bone quality: a retrospective analysis of 86 smr implants with surgical tips and tricks

Background: Stemless total shoulder arthroplasty (TSA) utilizes epiphyseal-metaphyseal fixation rather than diaphyseal anchoring. While anatomical stemless designs are established, stemless reverse total shoulder arthroplasty (RTSA) remains subject to clinical skepticism regarding primary fixation stability and the risk of early humeral loosening in older populations with potentially compromised bone quality.

Objective: This article evaluates the clinical and radiographic outcomes of stemless RTSA, identifies specific surgical challenges, and outlines a standardized technical protocol to optimize metaphyseal fixation.

Key Points: A retrospective analysis of 86 stemless RTSA procedures (mean age 71.4 years) demonstrated significant improvements in ASES, Constant, and SSV scores at a minimum two-year follow-up. Radiographic analysis of 52 patients showed stable implants with minimal humeral lysis. However, four cases of early non-traumatic loosening occurred, attributed to inadequate bone stock assessment. Essential technical requirements include preoperative CT/MRI imaging, intraoperative "thumb press" testing of metaphyseal density, and bone-sparing humeral preparation. The protocol emphasizes maintaining a 2mm cancellous margin, avoiding cortical contact, and utilizing size-specific reaming or impaction based on bone quality. Stemless designs facilitate easier revision, reduce blood loss, and preserve bone stock for potential future interventions or fracture management.

Conclusion: Stemless RTSA provides functional outcomes comparable to stemmed designs when appropriate bone quality is present. Success necessitates rigorous intraoperative assessment of the humeral metaphysis and a low threshold for transitioning to stemmed implants if bone density is insufficient for primary stability.