Researchers found the incidence of scapular notching in reverse shoulder arthroplasty was reduced as a result of the inferior offset glenosphere created by a glenosphere base plate design, particularly when the glenosphere was maximally offset inferiorly.
The researchers retrospectively reviewed the charts of 82 patients who underwent reverse shoulder arthroplasty with an eccentric glenosphere. Patients’ mean age was 74 years, and mean follow-up period was 26.3 months. Cuff tear arthropathy was an indicator for surgery for 63 patients, acute and chronic trauma was an indicator for five patients and revision total shoulder arthroplasty was the cause for surgery in 14 patients.
Using the five-grade Nerot-Sirveaux classification system, the researchers assessed the level of scapular notching on standard anteroposterior radiographs of the glenohumeral joint. On the latest follow-up radiograph, the researchers also studied the amount and degree of inferior glenosphere offset or inferior tilt, as well as the dial setting for the glenosphere component (A-E), the relationship of the glenosphere to the metaglene, and the presence of radiolucent lines and base-plate loosening. The researchers also obtained range of motion and Constant-Murley scores.
Results showed 73 patients had no notching, five had grade I notching, two had grade II notching and two had grade III notching. Overall, 11% of the patients had notching, which was found to be correlated with the amount of inferior offset.
There were five different dial settings for the glenosphere. Thirty-seven patients had a maximum inferior offset of 2 mm to 4 mm, where no radiographic notching was present. Two patients with grade III notching and four patients with grade I notching had a minimal inferior offset of 0 mm to 2 mm. Among the three patients with 0 mm of inferior offset, one was observed to have grade I notching and two had grade II notching. There was some interior tilt in most patients, according to the researchers.
From the preoperative to the follow-up examination, both range of motion and Constant-Murley scores improved in all patients. Range of motion and function outcomes were not significantly different in patients with notching and without notching, according to the researchers. – by Monica Jaramillo
Disclosures: Li is a paid consultant for DePuy-Mitek Sports Medicine and Tornier. Please see the full study for a list of all other authors’ relevant financial disclosures.