Neutral version, retroversion of humeral component may not impact outcomes of RSA
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Key takeaways:
- Reverse shoulder arthroplasty with the humeral component in neutral version or 30° of retroversion had similar 2-year outcomes.
- Surgeons can use their discretion when choosing version of the humeral component.
According to published results, patients who underwent reverse shoulder arthroplasty with the humeral component in either neutral version or 30° of retroversion had similar range of motion, pain scores and functional outcomes at 2-year follow-up.
J. Michael Wiater, MD, and colleagues randomly assigned 66 patients who underwent RSA to receive either neutral humeral version (n = 33; median age, 70 years) or 30° humeral retroversion (n = 33; median age, 71 years).
Outcome measures included American Shoulder and Elbow Surgeons scores, VAS pain scores, Patient-Reported Outcomes Measurement Information System-10 (PROMIS-10) physical scores, range of motion, muscle strength and complications.
At minimum 2-year follow-up, researchers found no significant differences between the groups in abduction, forward elevation, internal rotation, external rotation or muscle strength. In addition, they found no significant differences between the groups in ASES scores, VAS pain scores or PROMIS-10 physical scores.
In the neutral version group, one patient required revision for instability, one patient required revision for stiffness and seven patients had scapular notching. In the 30° retroversion group, one patient had an acromial stress fracture and five patients had scapular notching.
With similar outcomes across all measures, Wiater and colleagues concluded surgeons can use their discretion when choosing version of the humeral component during RSA.
Perspective
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Unfortunately, the quest for consistent shoulder rotation remains elusive following reverse shoulder arthroplasty. Authors, including myself, have hoped the solution would be as simple as adjusting the humeral version and have reported results along those lines in biomechanical studies. However, this paper nicely outlines that surgery in humans is often more complicated than it is in computer models and cadaveric experiments.
In this nicely designed and executed randomized control study, the authors found that humeral version had no effect on postoperative outcomes following RSA. It is not surprising they did not find a difference between groups, as shoulder rotation following RSA is a complex motion that involves multiple factors such as implant size and alignment, and the integrity of the surrounding muscles. In other words, there may not be a one-size-fits-all solution for maximizing rotation. Rather, a customized approach for each patient may be the answer moving forward.
As preoperative planning and intraoperative navigation become more refined over time, my hope is that this will result in improved rotation and function. In the meantime, we will have to keep managing patients’ expectations that they may have limited rotation after reverse shoulder replacement.
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