Short Humeral Stems in Shoulder Arthroplasty

Abstract

Since the introduction of shoulder arthroplasty by Neer in 1974, the design of not only the glenoid component but also the humeral component used in shoulder arthroplasty has continually evolved. Changes to the design of the humeral component include a gradually disappearing proximal fin; diversified surface finishes (such as smooth, grit-blasted, and porous coating); a more contoured stem from the originally straight and cylindrical shape; and the use of press-fit uncemented fixation as opposed to cemented fixation. Despite the evolution of the humeral component for shoulder arthroplasty, however, stem-related complications are not uncommon. Examples of stem-related complications include intraoperative humeral fractures, stem loosening, periprosthetic fractures, and stress shielding. These become much more common in revision arthroplasty, where patients are associated with further complications such as surgical difficulty in extracting the humeral component, proximal metaphyseal bone loss due to stress shielding, intraoperative humeral shaft fractures, and incomplete cement removal. Physicians have made many attempts to reduce these complications by shortening the stem of the humeral component. In this review, we will discuss some of the limitations of long-stem humeral components, the feasibility of replacing them with short-stem humeral components, and the clinical outcomes associated with short-stemmed humeral components in shoulder arthroplasty.

Keywords: Arthroplasty; Humeral component; Short stem; Shoulder.

Fig. 1.

Postoperative radiographs showing a standard long stem humeral component (A) and a short stem component (B) in reverse shoulder arthroplasty.

Fig. 2.

Perioperative complications related to long stem humeral component, such as intraoperative humeral shaft fracture (arrows), during inserting press-fit, cementless long stem on simple x-ray (A) and computed tomography image (B), intraoperative proximal metaphyseal fracture (arrows) that was fixed with cerclage wiring (C), and periprosthetic fracture (circle) due to simple fall after reverse shoulder arthroplasty (D).

Fig. 3.

Intraoperative photo of reverse shoulder arthroplasty using short humeral stem (the right shoulder in a 70-year-old female patient), showing preservation of bone stock in proximal humeral metaphysis at completion of metaphyseal reaming.

Fig. 4.

Radiographs showing a well-aligned, long humeral component (A) and valgus-aligned, short humeral component (B). A long stem humeral component can be inserted well aligned, extending down the medullary canal, while a short stemmed component is prone to valgus or varus malalignment due to lack of canal-based constraint during insertion.