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Concentric, eccentric glenosphere produced similar outcomes after reverse shoulder arthroplasty
Among patients who underwent reverse shoulder arthroplasty, there were no significant differences in notching rates or clinical outcomes for concentric and eccentric glenospheres, according to study results.
Intraoperatively, researchers randomly assigned 50 patients who were undergoing reverse shoulder arthroplasty (RSA) for the diagnosis of cuff tear arthropathy to receive either a concentric or eccentric glenosphere. Using an anteroposterior radiograph, the researchers assessed notching, and VAS pain score, shoulder function rating, American Shoulder and Elbow Surgeons score and Oxford shoulder score were used to assess clinical outcome. The researchers also assessed active forward elevation and external rotation. Mean follow-up was 43 months for patients in the concentric group and 47 months for patients in the eccentric group.
The groups had similar demographics and preoperative scores, according to the researchers. Postoperatively, four patients in the concentric group developed inferior scapular notching compared with one patient in the eccentric group at the time of final follow-up.
The inferior scapular notching ranged in size from 1.1 mm to 7.4 mm. However, no notching occurred in patients with glenoid overhang greater than 3.5 mm, according to the researchers.
With respect to functional outcome scores, patient satisfaction and shoulder motion, the researchers found no significant differences between the groups.
According to the researchers, limitations of the study included short follow-up and unknown long-term effects of eccentric glenospheres on baseplate fixation. They also found the low notching rate for patients in the concentric group suggests routine use of eccentric glenospheres may have limited additional benefit for the prosthesis, which could be specific to the prosthesis and may not apply to RSA designs with higher notching rates. The researchers also did not assess anterior or posterior notching due to difficulty in making standardized radiographs to evaluate notching.
Disclosures: Poon is a consultant for and received payment for lectures from LIMA. Astley received payment for lectures from LIMA.