Stem length in anatomic total shoulder arthroplasty: long stem, short stem, and stemless Biomechanical considerations, indications, and clinical performance

Background Anatomic total shoulder arthroplasty (aTSA) has become a valuable option for patients with degenerative glenohumeral joint disease, and traditional cemented long stems have been the gold standard for many years. Over the past decade, there has been a trend towards uncemented metaphyseal fixed short stems and stemless prostheses with the proposed advantages of bone-stock preservation and easier revision. Short- and mid-term results are promising; however, regarding long-term stability, a valid comparison with standard long-stem aTSA cannot be made yet. Furthermore, little is known about the biomechanical properties of such designs. Objectives The aim of this review is to provide an overview of the current literature on biomechanical considerations, indications, and clinical performance for three different anchoring systems. Methods A narrative review of current original studies (evidence level I-IV), systematic reviews, and meta-analyses of clinical outcomes and biomechanical properties was performed using PubMed and Cochrane Central Register of Controlled Trials (non-systematic literature search). Summery and practical conclusion There is a paucity of mid- and long-term clinical data after short-stem and stemless aTSA. Studies evaluating the influence of implant design on the biomechanical stability of humeral anatomical shoulder joint replacements are insufficient. Clinical long-term outcomes are needed to evaluate whether one anchoring concept is superior to another.