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Humeral component retroversion showed no impact on clinical outcomes of reverse shoulder arthroplasty
Patients who underwent reverse shoulder arthroplasty with humeral retroversion of at least 20° had no differences in clinical or radiologic outcomes compared with patients who had humeral retroversion of no more than 10°, results showed.
Alexander W. Aleem, MD, and colleagues categorized 64 patients undergoing reverse shoulder arthroplasty with the Zimmer Trabecular Metal Reverse Shoulder System (Zimmer Biomet) based on whether they had humeral retroversion of 10° or less (group A) or humeral retroversion of 20° or greater (group B). Researchers compared clinical outcomes, including American Shoulder and Elbow Surgeons (ASES) scores, range of motion and internal rotation function, as well as radiographic outcomes, between the two groups.
A comparison of the groups showed no clinical or statistically significant differences in ASES scores, as well as no differences in range of motion or the ability to perform tasks that required shoulder internal rotation. However, researchers noted statistical and clinical improvements in both groups postoperatively compared with preoperative scores. At final follow-up, group A had an average score of 77.8 and group B had an average score of 79.2. – by Casey Tingle
Disclosures: Aleem has received research support from Zimmer Biomet. Please see the full study for a list of all other authors’ relevant financial disclosures.
Perspective
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The study by Aleem and colleagues demonstrated no effect of humeral positioning on clinical outcomes with respect to internal and external rotation. This result is interesting in light of multiple biomechanical, cadaveric and computer simulation studies that clearly demonstrate differences in these motions with variances in humeral positioning. It is clear that limitation of the extent of internal and external rotation until component impingement occurs is based on positioning, size of the glenosphere and even humeral inclination. Therefore, this study invites the theory that scapulothoracic motion can compensate for limitations within a particular reverse system. It also raises the question of whether humeral version in itself, affects any major functional parameters including stability, range of motion, pain level and patient reported outcomes.
It is important to realize, however, the study examined a single arthroplasty system with a 150° humeral inclination angle which may not bear similar results in Grammont-style prostheses or in those systems with even lower angles of inclination (ie, 135° anatomic prostheses).