Review Question - QID 219979

Anatomic total shoulder arthroplasty (Treatment A) results, on average, in better internal and external rotation than reverse total shoulder arthroplasty (Treatment B), allowing improved ability to externally rotate at the side and internally rotate the shoulder to reach behind the back (Answer 4).

Patients with glenohumeral osteoarthritis and an intact rotator cuff are good candidates for anatomic total shoulder arthroplasty, in which the humeral head is replaced with an articulating metal head (with or without a stem) and a cemented polyethylene glenoid component. Because of this design, the construct is less constrained than a reverse total shoulder arthroplasty and requires an intact and functional rotator cuff to balance and counteract the shear forces across the glenoid that predispose the construct to mechanical loosening. The flip side of a less-constrained articulation, however, is that a greater amount of internal and external rotation can be preserved and achieved in the post-operative period when compared to a reverse arthroplasty. Despite this difference, both procedures achieve similar patient-reported outcome scores and similar total degrees of forward flexion.

Kim et al. reviewed the outcomes and complications of anatomical shoulder arthroplasty (aTSA) and reverse total shoulder arthroplasty (rTSA) for primary glenohumeral osteoarthritis with intact rotator cuff tissue. The authors performed a meta‐analysis using six studies that compared radiologic outcomes, functional scores, and range of motion (ROM) and found that range of motion, especially external rotation, was better for aTSA than for rTSA. They concluded that there was no difference in the revision rate at mid‐term follow‐up between aTSA and rTSA, with glenoid loosening being more common with aTSA versus scapular notching with rTSA, and that, overall, functional scores showed no difference between aTSA and rTSA.

Kiet et al. compared the outcomes after shoulder replacement between reverse and anatomic total shoulder arthroplasty. The authors performed a prospective, case-control study of 100 patients, and found that, at 2 years, there were no differences in the rate of major complications or revision surgeries, while outcomes assessed by the American Shoulder and Elbow Surgeons score and visual analog scale were also similar between the 2 groups. They concluded that TSA patients had greater external rotation than RTSA patients.

Figure A is an AP post-operative radiograph depicting an anatomic total shoulder arthroplasty. Figure B is an AP post-operative radiograph depicting a reverse total shoulder arthroplasty.

Incorrect Answers:
Answer 1: Anatomic TSA allows for a quicker return to activity post-operatively than reverse shoulder arthroplasty.
Answer 2: Anatomic TSA has been shown to provide improved (not equivalent) external rotation post-operatively.
Answers 3 and 5: Both anatomic and reverse shoulder arthroplasty provide improvements in forward flexion and patient-reported outcome scores without statistically significant differences in the current literature.