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

• Published in: Journal of shoulder and elbow surgery Vol. 27; no. 1; pp. 53 - 58
• Main Authors: Denard, Patrick J., Noyes, Matthew P., Walker, J. Brock, Shishani, Yousef, Gobezie, Reuben, Romeo, Anthony A., Lederman, Evan
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.01.2018
• Subjects: Adult; Aged; Aged, 80 and over; Arthritis - diagnostic imaging; Arthritis - etiology; Arthritis - surgery; Arthroplasty, Replacement, Shoulder - instrumentation; bone adaptations; Female; Humans; humeral loosening; Humerus - surgery; Male; metaphyseal fixation; Middle Aged; Osteolysis - diagnostic imaging; Osteolysis - epidemiology; Postoperative Complications - diagnostic imaging; Postoperative Complications - epidemiology; press fit; Prosthesis Design; Radiography; Range of Motion, Articular; Retrospective Studies; short stem; Shoulder Joint; Shoulder Prosthesis; stress shielding; Total shoulder arthroplasty; Weight-Bearing; Treatment Study; short stem; bone adaptations; press fit; humeral loosening; metaphyseal fixation; Retrospective Cohort Design; Total shoulder arthroplasty; stress shielding; Level III
• ISSN: 1058-2746; 1532-6500
• DOI: 10.1016/j.jse.2017.06.042

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. 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. 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. 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.