Stemless Shoulder Arthroplasty: Review of Early Clinical and Radiographic Results

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Humeral stem design in shoulder arthroplasty has evolved tremendously over the past 60 years. Neer first introduced modern shoulder arthroplasty in 1955 with his series of 12 patients treated with a hemiarthroplasty for fracture dislocations or fracture sequelae 1 . The humeral component was uncemented, was 15 cm in length, had 3 flanges at the neck for rotational control, and was constructed of Vitallium. It came in 3 different sizes: small, medium, and large. Appropriate implant sizing was determined preoperatively by taping the prosthesis to the lateral aspect of the arm and making an anteroposterior radiograph 1 . Following this, Neer reported his outcomes of 48 shoulders in 47 patients undergoing hemiarthroplasty for glenohumeral osteoarthritis with his first-generation stem, which included 5 different stem diameters, all of the same length, and a 44.5-mm head. He also reported on a revised design that was modified for implantation with cement 2 . Neer’s clinical results were considered excellent; in the 46 shoulders of the 45 patients who were evaluated at follow-up, 40 patients (89%) had excellent or satisfactory physician-rated results, and 42 patients (93%) were enthusiastic or satisfied with their results. There was no radiographic evidence of stem loosening, and there were also no postoperative infections or important complications 2 . However, surgeons began to understand the importance of re-creating patient-specific anatomy. This was first incorporated in the second-generation stem design with the concept of modularity, featuring separate heads and stems connected with a Morse taper. Further anatomic investigations of the proximal part of the humerus led to the design of the third-generation humeral implants, which allowed alteration of humeral head inclination and offset, in addition to stem and head sizes 3 . The majority of these designs still featured a standard-length humeral stem that engaged the diaphysis, and surgeons began to recognize the inherent difficulties with explantation in revision cases. Recently, this has led to the design of fourth-generation humeral components, which have evolved into short-stem or stemless designs that rely on fixation within the humeral metaphysis.
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