Stemmed versus stemless humeral implants in anatomic total shoulder arthroplasty (aTSA): A systematic review and meta-analysis

Background A recent advancement in anatomic total shoulder arthroplasty (aTSA) has been the development of stemless humeral implants The objective of this systematic review and meta-analysis is to compare outcomes of traditional stemmed humeral implants (S+) and stemless humeral implants (S-) in aTSA. Methods A search was conducted across seven databases. Titles and abstracts were screened for eligibility. Full texts were screened for inclusion. Demographic and study results were extracted from articles that met the inclusion criteria. Meta-analysis was conducted to evaluate outcomes. Results Twenty-one studies were included, of which nineteen met the inclusion criteria for meta-analysis. No studies were poor quality or at high risk of bias according to the quality assessment. A meta-analysis showed no significant difference in postoperative Constant Scores (Cohen's d=–0.27, 95%CI: –0.79 to 0.25, P=0.3), forward flexion(Cohen's d=-0.07, 95% CI: –0.32 to 0.17, P=0.56), abduction (Cohen's d=–0.07, 95%CI: –0.46 to 0.33, P=0.73), external rotation (Cohen's d=–0.12, 95%CI: –0.39 to 0.15, P=0.39), restoration of the center of rotation (Cohen's d=0.01, 95%CI: –0.58 to 0.60, P=0.97), or revision risk (Odds Ratio (OR)=1.14, 95%CI: 0.70–1.86, P=0.59). However, S- demonstrated a significant reduction in operative time (Cohen's d=1.20, 95%CI: 0.62 to 1.78, P<0.001) and intraoperative blood loss (d=0.65, 95%CI: 0.52 to 0.77, P< 0.001). (Odds Ratio (OR)=1.14, 95%CI: 0.70–1.86, P=0.59) Conclusion Both S+ and S- aTSA provide equivalent functional and clinical outcomes, with S- providing some potential benefits such as decreased intraoperative blood loss and operative time. This implant may be particularly beneficial in younger patients with preserved metaphyseal bone quality.