 Introduction/Background There has been a rapid increase in the number of shoulder arthroplasties, including partial or complete humeral head resurfacing, hemiarthroplasty, total shoulder arthroplasty, and reverse total shoulder arthroplasty, performed in the United States over the past 2 decades [1]. The most recent published estimates have reported a 2.5-fold increase in the number of shoulder arthroplasties performed between 1998 and 2008, from 19,000 to 47,000 [1,2]. Overall, total shoulder arthroplasties are the most common type, having surpassed hemiarthroplasties in the last decade [1]. Most shoulder arthroplasties are performed for degenerative conditions. Humeral head resurfacing is indicated in patients with humeral head osteonecrosis, large Hill-Sachs deformity, or focal osteoarthrosis. Hemiarthroplasties are typically performed in patients with osteoarthrosis limited to the humeral head or in patients with comminuted humeral head fractures. Hemiarthroplasties are also recommended in patients with deficient glenoid bone stock and in patients with greater preoperative comorbidities because they require a shorter intraoperative time compared with total shoulder arthroplasty. Presently, total shoulder arthroplasty is recommended over hemiarthroplasty for advanced shoulder osteoarthrosis because of its superior clinical outcome. Reverse shoulder arthroplasties were first introduced in 1987 as a treatment option for patients with a deficient rotator cuff and have been used as a salvage procedure for patients with failed total shoulder arthroplasties [3,4]. Reverse shoulder arthroplasties are constructed differently from total shoulder arthroplasties to compensate for the lack of stabilization related to the deficient rotator cuff. The glenoid component is a round metal ball (referred to as the glenosphere) attached to a baseplate along the glenoid surface, and the humeral component has a cup-shaped articular margin secured by a metal stem [4].
Imaging After Shoulder Arthroplasty PCAs.  Introduction/Background There has been a rapid increase in the number of shoulder arthroplasties, including partial or complete humeral head resurfacing, hemiarthroplasty, total shoulder arthroplasty, and reverse total shoulder arthroplasty, performed in the United States over the past 2 decades [1]. The most recent published estimates have reported a 2.5-fold increase in the number of shoulder arthroplasties performed between 1998 and 2008, from 19,000 to 47,000 [1,2]. Overall, total shoulder arthroplasties are the most common type, having surpassed hemiarthroplasties in the last decade [1]. Most shoulder arthroplasties are performed for degenerative conditions. Humeral head resurfacing is indicated in patients with humeral head osteonecrosis, large Hill-Sachs deformity, or focal osteoarthrosis. Hemiarthroplasties are typically performed in patients with osteoarthrosis limited to the humeral head or in patients with comminuted humeral head fractures. Hemiarthroplasties are also recommended in patients with deficient glenoid bone stock and in patients with greater preoperative comorbidities because they require a shorter intraoperative time compared with total shoulder arthroplasty. Presently, total shoulder arthroplasty is recommended over hemiarthroplasty for advanced shoulder osteoarthrosis because of its superior clinical outcome. Reverse shoulder arthroplasties were first introduced in 1987 as a treatment option for patients with a deficient rotator cuff and have been used as a salvage procedure for patients with failed total shoulder arthroplasties [3,4]. Reverse shoulder arthroplasties are constructed differently from total shoulder arthroplasties to compensate for the lack of stabilization related to the deficient rotator cuff. The glenoid component is a round metal ball (referred to as the glenosphere) attached to a baseplate along the glenoid surface, and the humeral component has a cup-shaped articular margin secured by a metal stem [4].