Review Question - QID 220035

A commonly seen "complication" following reverse total shoulder arthroplasty (rTSA) includes glenoid notching. Creating a varus neck-shaft angle in the humerus is a technical step that has been shown to prevent notching (Answer 4).

Reverse total shoulder arthroplasty is a procedure that has increased in frequency over the past several years, secondary to promising long-term data and an expanding list of indications. Like any procedure, the operation is not without complications, with notching considered the most common. While the impact of this complication remains somewhat unclear, some have noted its association with baseplate failure. Nonetheless, a number of technical steps have been described to avoid the phenomenon, including creating a varus neck-shaft angle (utilizing a 135 vs 155-degree stem, for example), lateralizing the glenosphere, positioning the glenosphere inferiorly, and employing a large glenosphere.

Cheung et al. reviewed the complication profile of rTSA, including neurologic injuries, intraoperative fracture, hematoma, infection, dislocation, acromion fracture, and notching. They note notching to be more prevalent in Grammont-style (155-degree) prosthesis, estimated to occur in 51-96% of patients. In contrast, for those with lateralized glenospheres, notching ranges from 0-13%. The authors conclude meticulous planning and familiarity is essential to avoid poor outcomes.

Gutiérrez et al. performed a sawbones study utilizing various implants, which included glenospheres of three different diameters (30, 36, and 42 mm), as well as three different centers of rotation offsets (0, +5, and +10 mm). These glenospheres were then positioned in three different locations of the glenoid (superior, middle, inferior) before implanting a humeral prosthesis, which demonstrated neck-shaft angles of 130, 150, or 170 degrees. The authors found varus humeral neck-shaft angle to be the most important factor, which was followed by inferior positioning of the glenosphere, lateral offset of the glenosphere, and finally increasing size of the glenosphere.

Figure A is an AP postoperative radiograph of a right rTSA. Figure B is an AP radiograph demonstrating notching of the inferior glenoid.

Incorrect Answers:
Answer 1: increasing, not decreasing, the glenosphere size will reduce the risk for notching.
Answer 2: humeral stem length has no role in preventing notching.
Answer 3: inferior positioning of the glenosphere will prevent notching.
Answer 5: lateralizing, not medializing, the glenosphere position will decrease the risk for notching.