Proximal stress shielding is decreased with a short stem compared with a traditional-length stem in total shoulder arthroplasty

Background: This study compared the outcome and radiographic humeral adaptations after placement of a traditional-length (TL) or short-stem (SS) humeral component during total shoulder arthroplasty (TSA). The hypothesis was there would be no difference in outcome or radiographic adaptations. Methods: A multicenter retrospective review was performed of primary TSAs performed with a TL or SS press-fit humeral component. The stems were identical in geometry and coating, with the only variable being stem length. Functional outcome and radiographs were reviewed at a minimum of 2 years postoperatively in 58 TL stems and 56 SSs. Results: There were significant improvements in all range of motion and functional outcome from baseline (P < .001) but no difference between the groups (P > .05). TL stems were placed in anatomic alignment 98% of the time compared with 86% of the SS cases (P = .015), but alignment did not influence outcome. Cortical thinning was more common in the medial metaphysis with the TL stem (74%) than with the SS (50%; P = .008). Partial calcar osteolysis was seen in 31% of TL stems and in 23% of SSs (P = .348). There was no difference in loosening or shift between the 2 groups. Conclusion: There is no difference in functional outcome at short-term follow-up between a TL stem and a SS in TSA. The pattern of radiographic adaptations may differ based on stem length. Further study is needed to evaluate the mid-to long-term differences, particularly with regard to calcar osteolysis. (C) 2017 Journal of Shoulder and Elbow Surgery Board of Trustees. All rights reserved.