Is wedge augmentation better than eccentric reaming in RSA?

Referenced article:  Reverse Shoulder Arthroplasty with and without Baseplate Wedge Augmentation in the Setting of Glenoid Deformity and Rotator Cuff Deficiency – A Multicenter Investigation

One of the most difficult surgeries in Reverse Shoulder arthroplasty remains the ability to correct for glenoid deformity with accurate reaming.  It remains a challenge even to the most experienced surgeons to appreciate how much version and inclination is corrected intra-operatively and how much bone loss is acceptable for long term survivorship.  The use of bone graft is another option to address significant retroversion, however complications as high as 25% have been reported with this technique.

This multi-centered retrospective review reports on mid-term (5+ years) outcomes comparing 87 wedged augment versus 84 standard baseplates in RSA with significant glenoid deformity (15-30° retroversion or 70-80° beta angle).  The augments included a mix of superior augments, posterior augments, and posterior/superior augments.  Augments demonstrated significantly greater improvements in ROM compared to the use of standard baseplate in abduction, forward elevation and external rotation at 5+ years.  Additionally, augments had better patient reported outcomes in ASES, Constant and Shoulder arthroplasty Smart score, and less VAS pain scores at 5+ years.  Importantly, in this cohort there was no significant difference in the rate of complications between augmented and standard baseplates.

This article reports on one of the largest cohorts comparing standard baseplates to augments in patients with severe glenoid deformity. In my opinion, this study is extremely useful for my practice and supports the use of metal augments for the treatment of glenoid deformity.   With an 8% complication rate, this is better than some reported outcomes of up to 25% with the use of bone graft for augmentation. These mid term results demonstrate reliable outcomes without increased revision rate.   Additionally, this study re-emphasizes the importance of lateralizing the shoulder with minimal bone loss in severe deformity with augments instead of eccentric reaming and medializing the center of rotation.  This allows the surgeon to improve the deltoid wrap which plays an integral role in patient range of motion and patient reported outcomes as evidence with the reported results.  In conclusion, with a low rate of complication, superior outcomes in ROM, PROs and pain compared to standard baseplate, a metal augment is my preferred choice to address significant glenoid deformity and has become a staple in my practice.

Stephanie Muh, MD, is a paid surgeon consultant of Exactech.

References:

1. Levin J et al. Reverse shoulder arthroplasty with and without baseplate wedge augmentation in the setting of glenoid deformity and rotator cuff deficiency – a multicenter investigation. J Shoulder Elbow Surg (2022). In press.