Radiographic alignment of short stem humeral components in shoulder arthroplasty: a multicenter study

Introduction: Short stem humeral stem components represent an area of potential advancement that may decrease the risk of complications associated with traditional length stems, but early data has demonstrated a high rate of malalignment with certain designs. The utilization of a short stem specifically designed to self-align in the proximal portion of the diaphysis has the potential to provide more consistent adequate alignment. Methods: A multicenter retrospective review was performed on 269 shoulders that had undergone an anatomic Total shoulder arthroplasty or a reverse shoulder arthroplasty with implantation of a self-aligning short stem humeral component. Radiographic outcomes included stem alignment and fill-fit ratios. Results: Radiographs showed adequate stem alignment in 94% of the shoulders. The differences in the superior region canal-fill ratio between the neutral and malaligned group were statistically significant (P < .0003), and the canal-fill rations in the inferior region were also statistically different between the 2 groups (P < .0001). The trend demonstrated higher fill ratios for the neutral stems. Conclusion: The self-aligning short stem analyzed in this study provided a very high rate of adequate stem radiographic alignment. Higher fill ratios were correlated with improved stem alignment. Further studies are needed to understand if improved initial alignment rates correlate with improved patient outcomes or a decreased rate of mechanical failure or other complications.